The Familial Phylogeny

of the Tetraodontiformes

(Acanthopterygii: Pisces)

as Evidenced by Their

Comparative Myology

RICHARD WINTERBOTTOM

m

4

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY • NUMBER 155
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SMITHSONIA N CONTRIBUTION S T O ZOOLOG Y • NUMBE R 15 5

The Familial Phylogeny

of the Tetraodontiformes

(Acanthopterygii: Pisces)

as Evidenced by Their

Comparative Myology

Richard Winterbottom

SMITHSONIAN INSTITUTION PRESS

City of Washington

1974
ABSTRACT

Winterbottom, Richard. The Familial Phylogeny of the Tetraodontiformes

(Acanthopterygii: Pisces) as Evidenced by Their Comparative Myology. Smithsonian Contributions to Zoology, number 155, 201 pages, 185 figures, 1974.—The

myology of 46 species of the order Tetraodontiformes is described, the species

representing the 11 families initially recognized for the purposes of this study.

The data gathered from the descriptions has been interpreted phylogenetically,

using only those characters of a shared specialized (synapomorph) nature. This

analysis suggests that the Triacanthodidae and Triacanthidae are sister groups,

and separated off first from the ancestral stock. The remaining families are

divided into two lines. On the one hand, the Balistidae form the sister group

of the Monacanthidae, and together form the sister group of the Aracanidae

and Ostraciidae. In the other lineage, the Triodontidae separated off first, followed by the Molidae. The Diodontidae form the sister group of the Tetraodontidae plus Canthigasteridae.

In the final analysis, such fossils as are considered pertinent to the understanding of tetraodontiform phylogeny are considered. The information provided by these fossils, combined with the results of the myological interpretations,

suggest the following systematic changes in the hierarchical classification of

tetraodontiforms in order to bring it into line with the proposed phylogeny:

(1) that two suborders be provisionally recognized, the first containing the

Triacanthodidae and Triacanthidae, the second consisting of two superfamilies;

(2) that a superfamily Balistoidea be recognized to contain the families Balistidae,

fSpinacanthidae, and Ostraciidae; (3) that the families Monacanthidae and

Aracanidae be treated as subfamilies of the Balistidae and Ostraciidae respectively, and that the fSpinacanthinae of Tyler (1968) be removed from the

Triacanthodidae and placed as the sister group of the Balistidae, with equal

rank (as fSpinacanthidae); (4) that a superfamily Tetraodontoidea be formed

to contain the families tEoplectidae, Triodontidae, Tetraodontidae, Diodontidae,

and Molidae, and, should -fZignoichthys prove to be further along the gymnodont

line than fEoplectus, as hinted by Tyler (1972) and tentatively preferred here,

the fZignoichthyidae; (5) that the family Canthigasteridae be reduced to subfamilial rank within the family Tetraodontidae. and that the fEoplectinae of

Tyler (1972) be transferred from the Triacanthodidae to the superfamily Tetraodontoidea and raised to familial rank, in keeping with its phylogenetic position.

OFFICIAL PUBLICATION DATE is handstamped in a limited number of initial copies and is recorded

in the Institution's annual report, Smithsonian Year. SI PRFSS NUMBER 4823. SERIES COVER DESICN:

The coral Montastrea cavernosa (Linnaeus) .

Library of Congress Cataloging in Publication Data

Winterbottom, Richard, 1944—

The familial phylogeny of the Tetraodontiformes.

(Smithsonian contributions to zoology, no. 155)

1. Tetraodontiformes—Anatomy. 2. Phylogeny. 3. Muscles. 4. Fishes—Evolution. I. Title.

II. Series: Smithsonian Institution. Smithsonian contributions to zoology, no. 155.

QL1.S54 no. 155 [QL639] 591'.08s [597'.58] 73-2684

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Washington, D.C. 20402 - Price $2.80 (paper cover)
Contents

Page

Introduction 1

Acknowledgments .. 3

Materials, Methods, and Terminology 4

Myological Descriptions of Representative Triacanthodids 5

Subfamily Triacanthodinae 6

Triacanthodes anomalus (Schlegel) 6

Tydemania navigatoris Weber 11

Macrorhamphosodes platycheilus Fowler 12

Halirriochirurgus centriscoides Alcock 12

Subfamily Hollardiinae 12

Parahollardia lineata (Longley) 12

Hollardia hollardi Poey 13

Summary of Triacanthodidae 13

Myological Descriptions of Representative Triacanthids 13

Trixiphichthys weberi (Chaudhuri) 13

Triacanthus biaculeatus (Bloch) 18

Tripodichthys oxycephalus (Bleeker) 18

Summary of Triacanthidae 18

Myological Descriptions of Representative Balistids 18

Balistes vetula Linnaeus 19

Balistapus undulatus (Mungo Park) 24

Melichthys niger (Bloch) . 24

Rhinecanthus aculeatus (Linnaeus) 25

Odonus niger (Riippell) 25

Summary of Balistidae 25

Myological Descriptions of Representative Monacanthids 25

Pervagor melanocephalus (Bleeker) 26

Stephanolepsis auratus (Castlenau) 31

Paramonacanthus barnardi Fraser-Brunner 31

Chaetoderma spinosissimus (Quoy and Gaimard) 31

Paraluteres prionurus (Bleeker) . 31

Cantherhines pardalis (Riippell) 32

Oxymonacanthus longirostris (Bioch and Schneider) 32

Pseudalutarius nasicornis (Schlegel) 33

Ahiterus monoceros (Linnaeus) 33

Aluterus heudeloti Hollard 34

Aluterus schoepfi (Walbaum) 34

Anacanthus barbatus Gray 34

Summary of Monacanthidae 35

Myological Descriptions of Representative Aracanids 35

Kentrocapros aculeatus (Houttuyn) 35

Capropygia unistriata Kaup 39

ui
Page

Myological Descriptions of Representative Ostraciids 40

Ostracion tuberculatus Linnaeus 40

Lactoria cornuta (Linnaeus) 44

Tetrosomus concatenatus (Bloch) 44

Acanthostracion quadricornis (Linnaeus) 45

Summary of Ostraciidae 45

Myological Description of the Representative Triodontid 45

Triodon macropterus Lesson 45

Myological Descriptions of Representative Tetraodontids 50

Lagocephalus lunaris (Bloch and Schneider) 50

Amblyrhynchotes honckenii (Bloch) 56

Colomesus psittacus (Bloch and Schneider) 56

Xenopterus naritus (Richardson) 57

Arothron immaculatus (Bloch) 57

Tetraodon schoutedeni Pellegrin 58

Summary of Tetraodontidae 58

Myological Descriptions of Representative Canthigasterids 58

Canthigaster margaritatus (Riippell) 58

Canthigaster valentini (Bleeker) 63

Myological Descriptions of Representative Diodontids 63

Diodon hystrix Linnaeus 63

Chilomycterus orbicularis (Bloch) 68

Chilomycterus schoepfi (Walbaum) 68

Summary of Diodontidae 68

Myological Descriptions of Representative Molids 69

Mola mola Linnaeus 69

Ranzania laevis (Pennant) 72

Phylogenetic Significance of Observed Myological Variation 73

Interpretation 74

Discussion 90

Alternative Interpretations 94

A New Classification of the Tetraodontiformes 97

Literature Cited 100

List of Abbreviations 104

Figures 1-185 106-201

IV
The Familial Phylogeny

of the Tetraodontiformes

(Acanthopterygii: Pisces)

as Evidenced by Their

Comparative Myology

Richard Winterbottom

Introduction

This paper represents an attempt to elucidate the

familial phylogeny of the order Tetraodontiformes,

using a comparative myological approach. Past

classifications, usually based on external characters,

osteology or both, have often been vague concerning the precise interrelationships of the families,

although certain family groupings have been almost

universally accepted. Since the aim is to resolve the

familial phylogeny, the eleven families recognized

by Tyler (1970a) are provisionally accepted rather

than the seven families proposed by Greenwood,

et al. (1966). This approach is used in order to

facilitate recognition of evolutionary lines that

may become obscured in a more compressed

classification.

For a group supposedly derived from a perciform

or preperciform stock, the Tetraodontiformes (of

which there are some 320 Recent species) are very

diverse in size, shape, habits, habitats, and diet.

The morphological changes associated with these

variations can be expected to be reflected in the

anatomy, particularly in the myology. Myological

Richard Winterbottom, J. L. B. Smith Institute of Ichthyology, Rhodes University, Grahamstown, Republic of South

Africa.

changes appear to be of a grosser and less subtle

nature (and thus more obvious) than those

involving other facets of the functional systems.

Since this paper represents one of the first

attempts at detailed phylogenetic interpretation

from a purely myological standpoint, it seems necessary to outline certain factors influencing myology.

The evolutionary mechanism of muscular change

may be by the subdivision of new sections from

existing muscles, the reduction and ultimate loss

of a muscle, or change in fiber direction, since

these alterations have functional significances.

There are two extreme muscle types (pinnate and

parallel), with a complete gradation between them.

In pinnate muscles, the fibers converge on a central

axis (usually a tendon), while they lie parallel to

one another in a parallel fibered muscle. The two

types are apparently capable of the same amount

of work (Alexander, 1968:19). Perhaps more important than work in an evolutionary context is (are)

the advantage (s) conveyed by the different fiber

arrangements. Parallel fibered muscles provide

maximum excursion, and can be arranged as thin

sheets. Pinnation allows the localization of forces,

the accommodation of the muscle in an otherwise

unsuitable place (e.g., a narrow bony canal), and

the possibility of moving the tendon in two planes
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

by asymmetric contraction (Gans and Bock, 1965:

141-142). There is no evidence as to which of the

two types (if either) is phylogenetically the older in

vertebrates. Muscles affect a multidimensional

system, and therefore a change in any one muscle

is likely to produce changes in other muscles serving

the same system. The synergistic interactions of

bones, nerves, blood vessels, and ligaments with

each other and with the muscles are also subject

to this interpretion, of course, although not quite

so obviously. The apparent ease with which muscle

fibers can migrate and rearrange themselves (as

evidenced, for example, by individuals with deformed limbs or jaws), coupled with the rigidity

necessary for the application of muscle force at

the most suitable point of the lever system makes

comparative myology a particularly useful and

rewarding field of study.

Although the data gathered here for phylogenetic

interpretation can be utilized in a number of other

ways (e.g., functional evolution, systematic definition), this lies beyond the scope of this study. The

view that interpretations of phylogeny are only

meaningful if based on the presence of shared,

specialized (synapomorphic) characters is finding

increasing acceptance among biologists. This

process inevitably results in assumptions about the

probable homology and character state (i.e., plesiomorph vs. apomorph) of the characters, and the

weighting of these characters is a necessary and

integral part of the process. While the utilization of

synapomorphic characters in the elucidation of

phylogeny is unlikely to produce much disagreement, the incorporation and reflection of that

phylogeny in a hierarchical classification is still

avoided by certain biologists. I agree with Mayr

(1969:78) when he states, "The evolutionist believes

that a classification consistent with our reconstruction of phylogeny has a better chance of meeting

these objectives, [i.e., maximum information content with maximal ease of retrieval] than any other

method of classification." I have therefore attempted to reorganize the classification of the tetraodontiforms to reflect the phylogenetic picture derived

from the myology, using the basic methods set out

by Hennig (1966) and Brundin (1966, 1968).

Although muscles are described in terms of the

bones they attach to (and hence perhaps an osteological summary should be included), the reader

is referred to the detailed osteological investigations

of Tyler (1962a, 1962b, 1962c, 1963a, 1963b, 1968,

1970a, 1973) for information on this topic.

Numerous papers contain sparse observations on

the muscles of tetraodontiforms, with varying degrees of accuracy. These include the works of

Cuvier (1817), E. Geoffroy Saint-Hilaire (1818); I.

Geoffroy Saint-Hilaire (1827), Meckel (1828),

Goodsir (1841), Cleland (1862), Owen (1866),

Thilo (1879, 1896, 1899, 1914, 1920), S0rensen

(1883, 1884), Wiedersheim (1887), Borcea (1906),

Maurer (1912), Lubosch (1917, 1938), Takahasi

(1917), Soucte (1932a, 1932b, 1932c, 1935), Gregory and Raven (1934), van Dobben (1935), Edgeworth (1935), Nishi (1938), Raven (1939a, 1939b),

Gabriel (1940), van Roon (1942), Kesteven (1943),

Monod (1950, 1959a, 1959b, 1960), Le Danois

(1958), and Winterbottom (1970).

Of the more detailed papers, Winther (1877),

Lubosch (1929), and van Roon and ter Pelkwijk

(1940) described the jaw muscles, Dietz (1914) the

jaw and branchial muscles, Grenholm (1923) the

muscles of the fins, Rosen (1913), Parr (1927), and

Winterbottom (1971a) aspects of the body musculature, while Willem (1941, 1942, 1944, 1945, 1947a,

1947b, 1949) and Sarkar (1960) considered the

functional workings of the tetraodontiform head.

Le Danois (1955, 1959, 1961) has made extensive

observations on the myology of the "Orbiculates"

(a group containing the gymnodonts and ostracioids). Few of these papers contain any reasoned,

phylogenetic remarks. Winther (1877:462-463) accepted Cuvier's (1817) Sclerodermi (balistoids and

ostracioids), and suggested that the Triacanthidae

were specialized relatives. He felt, however, that

the gymnodonts were most closely related to the

"Discobali" (=Cyclopteridae), a conclusion which

has not, as far as I am aware, been supported since

then. Lubosch (1929) made certain general conclusions, but these suffer from the wide scope of

the work in relation to the number of species

examined. The placement of the Acanthuridae

between the Balistidae and Triacanthidae in the

text may indicate that Lubosch felt them to be

tetraodontiforms, but this is not explicitly stated.

Grenholm (1923:245), while stating that the tetraodontiforms were a well-defined group (and probably closely related to the Acanthuridae), felt that

the separation of the order into scleroderms and

gymnodonts was difficult to maintain (". . . schwer

afrecht zu erhalten"), although he gave no reasons
NUMBER 155

for this opinion. Willem, in his (1942:19-21) paper,

concluded that among the scleroderms, the acanthurids were the most generalized, followed either

by the triacanthids or the monacanthids, with the

balistids the most specialized. Later (1944), Willem

placed the chaetodontid fishes in the tetraodontiforms (=his "Plectognathes").

In her definition of the "Orbiculates"—the

ostracioid and gymnodont fishes—Le Danois

(1955) regarded the following myological characters

as primitive, and used them to define the suborder:

musculature complex, subcutaneous and trapezoidal muscles present. As discussed above, it has

recently been realized that primitive (symplesiomorph) characters cannot be used to link groups

phylogenetically. Additionally, complexity of muscles is a sign of specialization, not of antiquity;

subcutaneous muscles are found elsewhere (e.g.,

Antenariidae), and certainly could not exist where

discreet, overlapping scales (surely a "primitive"

condition for the teleosts) are present. "Trapezoidal" muscles present somewhat of an enigma. The

anteroventral muscle (the "trapeze inferieur" of

Le Danois, 1959) is the protractor pectoralis (derived from the levator series of the branchial arches,

and innervated by the vagus nerve), while her

"trapeze superieur" is derived from the anterior

trunk myomeres, and is innervated by an occipitospinal nerve. The protractor pectoralis occurs

regularly throughout the Euteleostei (Division III)

of Greenwood, et al. (1966, 1967) except in most, if

not all, members of the Protacanthopterygii (sensu

Rosen and Patterson, 1969). The levator pectoralis

has only been reported as a separate muscle from

certain families of Rosen and Patterson's (1969)

Series Percomorpha. Thus, the presence of two

"trapezoidal" muscles in the "Orbiculates" is more

in keeping with an alignment of these fishes with

groups of at least the percomorph level of organization, rather than with the "malacopterygian"

level (to which Le Danois felt they were related).

Parenthetically, it should be noted that the last

two of these three myological characters are not

found in ostracioids. The comparative reader will

find certain discrepancies between Le Danois'

myological descriptions and those given here. The

phylogenetic conclusions reached by Tyler in his

various publications on tetraodontiform osteology

will be reviewed in the discussion section of this

paper.

ACKNOWLEDGMENTS.—This paper represents the

major portion of a doctoral dissertation submitted

to the School of Graduate Studies, Queen's University, Kingston, Ontario, Canada.

I wish to express my deepest gratitude to Dr.

James C. Tyler of the Academy of Natural Sciences,

Philadelphia (ANSP), whose stimulating interest and

helpful advice has formed the mainspring of this

study. He has freely made available his detailed

knowledge of the tetraodontiforms, and supplied

much unpublished osteological information as well

as most of the specimens dissected. Dr. Tyler has

generously commented on both the dissertation and

much of the manuscript, although he is not necessarily in agreement with the phylogenetic relationships as presented here, and certainly disagrees with

the classificatory approach taken by the author.

To Dr. S. H. Weitzman of the Smithsonian Institution, Washington, D.C., I express my thanks for

his encouragement to complete the manuscript and

to maintain it in its entirety, and for his comments

on the text.

I thank my Ph.D. supervisor, Dr. J. Allen Keast,

for his guidance and advice throughout the study

period, and for making travel funds readily available to me. Various members of staff and graduate

students at Queen's University Biology Department

were always ready to discuss my problems with me

(particularly Drs. A. E. Downe and C. H. Hood,

and Messrs. Amundrud, McLaughlin, and van der

Kloet), and their help is greatly appreciated.

In addition, dissection material and discussions

are gratefully acknowledged from the following:

Drs. T. Abe of the University of Tokyo and H.

Britski of the Universidade de Sao Paulo (for

donating the specimens of the rare Triodon), J. G.

Field of the University of Cape Town, P. H. Greenwood and G. Palmer of the British Museum (Natural History) (BM (NH)), D. E. McAllister and C. G.

Gruchy of the National Museum of Canada (NMC),

J. E. Randall of the Bernice P. Bishop Museum,

M. M. Smith of the J. L. B. Smith Institute, J. H.

Wallace of the Oceanographic Research Institute,

Durban, R. McN. Alexander, W. C. Freihofer and

H. Jessen. For the many hours they spent discussing

phylogeny, the manuscript, and fishes with me, I

would like to thank Drs. G. J. Nelson and D. E.

Rosen of the American Museum of Natural History.

To my wife Irina I extend my gratitude for her

patience in dealing with my frequent unintelligible
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

soliloquys.

Support during this study came from R. Samuel

McLaughlin Scholarship and Fellowships (Queen's

University), a National Research Council Postgraduate Scholarship, and a Jessup Fund Award

from the Academy of Natural Sciences, Philadelphia, for the summer of 1969. The dissertation was

rewritten in part for publication during the tenure

of a Postdoctoral Research Fellowship at the

Smithsonian Institution, Washington, D.C.

Materials, Methods, and Terminology

The nomenclature of the muscles used in this

paper is taken from a descriptive synonymy of

teleostean muscles at present in preparation by the

author. In the case of the muscles to the rudimentary balistoid pelvic fin, the nomenclature is based

on the assumption that the fin ray elements represent the pelvic spines. In the descriptive section,

the muscles have been grouped according to convenient body regions.

Osteological nomenclature is based on Tyler

(1962a, 1970a) except for the hyoid arch, where

Nelson (1969) has been followed. The suture lines

shown in the figures are approximate, and are

included for reference purposes only. For accurate

outlines of the bones, see Tyler's various publications on tetraodontiform osteology.

Specimens for the most part were dissected under

a Wild M-5 stereoscopic research dissecting microscope. Rough pencil drawings were made on bristol

board with the aid of a Wild M-5 camera lucida

attachment. Detail was filled in freehand from the

dissection, the drawing then being inked in. Bone

and cartilage—stippled; muscles—lined with long

and short dashes; connective tissue—filled with

wavy lines; tendons, aponeuroses and ligaments—

short dashes; coelom—crosshatched. Bones are only

labeled in the figures of species dissected in detail

for each family; the muscle abbreviations being

underlined for clarity in these figures. Caudal fin

rays are numbered from the midline, those above

being prefixed by "D", those below by "V". Numerical differences arising from the number of fin

rays in any fin are not considered.

The musculature of representatives of the following families, and in the following order, are

described: Triacanthodidae, Triacanthidae, Balistidae, Monacanthidae, Aracanidae, Ostraciidae,

Triodontidae, Tetraodontidae, Canthigasteridae,

Diodontidae, and Molidae. The following group

terms are used provisionally to contain more than

one family: balistoid (Balistidae + Monacanthidae),

ostracioid (Aracanidae + Ostraciidae), tetraodontoid (Tetraodontidae + Canthigasteridae), and

triacanthoid (Triacanthodidae + Triacanthidae).

The latter group may not be phylogenetically valid,

and will be used for convenience only. The

Cuvierian term "gymnodont" will be used initially

to designate the Triodontidae + Molidae + Diodontidae + tetraodontoids.

The following is a list of the material examined,

arranged alphabetically by family. The number in

parentheses indicates the number of specimens

examined. Catalog abbreviations are clarified in

"Acknowledgments."

ARACANIDAE. — Capropygi a unistriat a Kaup :

ANSP 109574, (1), 67 mm SL, Kingston, South

Australia. Kentrocapros aculeatus (Houttuyn):

ANSP 117531, (2), 91 and 92 mm SL, no data,

received from T. Abe.

BALISTIDAE.—Balistapus undulatus ( M u n g o

Park): ANSP 108832, (1), 159 mm SL, Ressource

Islands, Indian Ocean; ANSP 117598, (1), 83 mm

SL, Inhaca Island, Indian Ocean. Balistes vetula

Linnaeus: ANSP 105508, (1), 111 mm SL, Estado

Sucre, Venezuela; ANSP 117535, (1), 137 mm SL,

no data, aquarium specimen. Melichthys niger

(Bloch): ANSP 117515, (1), 153 mm SL, no data,

aquarium specimen. Odonus niger (Riippell):

ANSP 102779, (1), 257 mm SL, Amirante Islands,

Indian Ocean. Rhinecanthus aculeatus (Linnaeus):

ANSP 117546, (1), 159 mm SL, Johnston Island,

Hawaii; ANSP 117544, (1), 175 mm SL, no data,

received from J. H. Wallace.

CANTHIGASTERIDAE. — Canthigaster margaritatus

(Ruppell): ANSP 117517, (1), 52 mm SL, no data,

received from M. M. Smith. Canthigaster valentini

(Bleeker): ANSP 117534, (1), 45 mm SL, Seychelles

Islands, Indian Ocean.

DIODONTIDAE.—Chilomycterus orbicularis (Bloch):

ANSP 117510, (1), 80 mm SL, no data, received

from M. M. Smith. Chilomycterus schoepfi, (Walbaum): ANSP 117518, (1), 138 mm SL, beach at

Kitty Hawk, North Carolina. Diodon hystrix Linnaeus: NMC 68-997, (1), 77 mm SL, Tres Maria,

Mexico; ANSP 117553, (1), 291 mm SL, Kaneohe

Bay, Hawaii.
NUMBER 155

MOLIDAE.—Mola mola Linnaeus: BM (NH)

1938.6.23.38, (1), 287 mm SL, off Chousi, Japan;

NMC 67.298, (1), 500 mm SL, off Newfoundland.

Ranzania laevis (Pennant): ANSP 106723, (1), 93

mm SL, Hawaii.

MONACANTHIDAE.—Aluterus heudelotii Hollard:

ANSP 103224, (1), 110 mm SL, Guinea, West

Africa. A. monoceros (Osbeck): ANSP 117498, (1),

160 mm SL, R/V Oregon (Station 10523); ANSP

117554, (2), 345 and 350 mm SL, no data, received

from J. Field. A. schoepfi (Walbaum): ANSP 101843,

(1), 106 mm SL, Caribbean, off Columbia. Anacanthus barbatus Gray: ANSP 117516, (1), 166 mm SL,

Gulf of Thailand. Cantherhines pardalis (Riippell): ANSP 117529, (1), 61 mm SL, Inhaca Island,

Indian Ocean; ANSP 117530, (1), 126 mm SL, no

data, received from M. M. Smith. Chaetoderma

spinosissimus (Quoy and Gaimard): ANSP 117514,

(1), 42 mm SL, Gulf of Thailand. Oxymonacanthus

longirostris (Bloch and Schneider): ANSP 117496,

(1), 72 mm SL, Zanzibar; ANSP 104791, (1), 72

mm SL, Amirante Islands, Indian Ocean. Paraluteres

prionurus (Bleeker): ANSP 106644, (1), 57 mm SL,

Farquhar Islands, Indian Ocean. Paramonacanthus

barnardi Fraser-Brunner: ANSP 117506, (1), 78 mm

SL, Natal, South Africa. Pervagor melanocephalus

(Bleeker): ANSP 117500, (2), 66 and 85 mm SL,

Taiwan; ANSP 117512, (1), 87 mm SL, Mocambique Island, Indian Ocean. Pseudalutarius nasicomis (Schlegel): ANSP 100830, (1), 45 mm SL,

Bay of Bengal. Stephanolepis auratus (Castlenau):

ANSP 117526, (1), 64 mm SL, Delagoa Bay, South

Africa; ANSP 117521, (2), 69 and 82 mm SL, Natal,

South Africa.

OSTRACIIDAE.—Acanthostracion quadricornis (Linnaeus): ANSP 98848, (1), 126 mm SL, Atlantic

Ocean, off South America. Lactoria cornuta (Linnaeus): ANSP 117540, (1), 50 mm SL, Natal, South

Africa; ANSP 117538, (1), 92 mm SL, no data,

received from M. M. Smith; ANSP 117539, (1), 176

mm SL, no data, received from J. H. Wallace.

Ostracion tuberculatus Linnaeus: ANSP 117542,

(2), 102 and 157 mm SL, no data, received from

}. H. Wallace. Tetrosomus concatenate (Bloch):

ANSP 117555, (2), 196 and 200 mm SL, no data,

received from M. M. Smith.

TETRAODONTIDAE. — Amblyrhynchotes honckenii

(Bloch): ANSP 117547, (1), 106 mm SL, Cape Province, South Africa. Arothron immaculatus (Bloch):

ANSP 117528, (1), 68 mm SL, no data, received

from M. M. Smith. Colomesus psittacus (Bloch and

Schneider): ANSP 98887, (1), 117 mm SL, off

Surinam. Lagocephalus lunaris (Bloch and Schneider): ANSP 113639, (3), 118, 124, and 137 mm SL,

Malaysia. Tetraodon schoutedeni Pellegrin: ANSP

117501, (1), 62 mm SL, Congo River at Leopoldville. Xenopterus naritus (Richardson): ANSP

117495, (2), 102 and 120 mm SL, Bay of Bengal.

TRIACANTHIDAE. — Triacanthus biaculeatus

(Bloch): ANSP 111536, (1), 111 mm SL, off Kerala

State, India. Tripodichthys oxycephalus (Bleeker):

ANSP 89397, (1), 82 mm SL, Paknam, Siam. Trixiphichthys weberi (Chaudhuri): ANSP 117492, (2),

115 and 122 mm SL, Bay of Bengal.

TRIACANTHODIDAE.—Halimoch irurgus cent riscoides Alcock: ANSP 117494, (1), 114 mm SL, Bay

of Bengal. Hollardia hollardi Poey: ANSP 117491,

(2), 53 and 92 mm SL, off Honduras. Macrorhamphosodes platycheilus Fowler: ANSP 117533, (2), 79

and 88 mm SL, Bay of Bengal. Parahollardia lineata (Longley): ANSP 101031, (1), 68 mm SL, Gulf

of Mexico. Triacanthodes anomalus (Schlegel):

ANSP 101256, (1), 74 mm SL, Honshu, Japan;

ANSP 117493, (1), 87 mm SL, Honshu, Japan.

Tydemania navigatoris Weber: ANSP 117532, (1),

73 mm SL, Bay of Bengal.

TRIODONTIDAE. — Triodon macropterus Lesson:

ANSP 103902, (3), 270, 350, and 350 mm SL,

Ryukyu Islands, Pacific Ocean; ANSP 98916, (1),

382 mm SL, Bonin Island, Pacific Ocean.

Myological Descriptions of Representative Triacanthodids

The general body outline of these fishes is represented in Figure 1. The sample size of the two

subfamilies is four out of nine genera for the

Triacanthodinae and two out of two genera for

the Hollardiinae.

The latter subfamily is found mainly in the

Caribbean (with one exception presently recorded

only from HaAvaii), while the triacanthodins extend

broadly from the east coast of Africa to the western

Pacific. Triacanthodids are usually benthic or bathypelagic fishes, living well below 100 fathoms.

They appear to feed predominantly on marine
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

invertebrates, with the exception of Macrorhamphosodes, in whose gut nothing but scales of other

fishes has yet been found.

The rounded caudal fin and rather deep body of

these fishes implies that they are not fast swimmers,

while the protractile jaws (of at least the more

conservative genera) evidences that their prey is

active. The jaws, however, are not protrusile in

the percoid manner, since the process here is completely passive (i.e., no active part is played by

the maxilla in protruding the premaxilla). They

are apparently incapable of closing the mouth with

the premaxillae still in the protruded position (the

advantages of such a maneuver are discussed by

Alexander, 1967).

Figure 48 shows the overall structure of the jaws

of Triacanthodes anomalus and Triacanthus biaculeatus (a triacanthid). The maxilla (Figures 4Sc,d)

is a fairly broad plate, the dorsal region curving

inward toward the midline. The fact that it is a

broad bone and not rodlike indicates that it is

incapable of rotating about its vertical axis, a

movement essential in the protrusion of the percoid

jaw. The dorsomedial region of the maxilla has

developed an external and internal flange. These

two flanges together form a groove containing the

lateral margin of the ascending process of the

premaxilla. From the lateral face of the inner flange

of the maxilla there arises a continuous sheet of

tough ligamentous tissue (the maxillopremaxilla

ligament) which passes dorsomedially to attach to

the ventromedial face of the ascending process of

the premaxilla. Neither the posteroventral face of

the maxilla, nor the anterior surface of the ethmovomer region where the maxilla articulates show

any evidence of the cartilagenous pad found there

in percoids. This indicates that the maxilla can

only move in one direction, since in most cases of

joints with two degrees of freedom (a higher pair)

there is a cartilagenous meniscus or pad allowing

this type of movement (Alexander, 1967). It seems,

then, that the maxilla cannot function as it does

in percoids. From the anterodorsal region of the

maxilla the maxilloethmoid ligament passes posteriorly to the ethmoid bone. Immediately beneath

its attachment to the maxilla is the anterior process

of the palatine, which rests in a concavity in the

maxilla (Figure 486). In perciform fishes with protrusile jaws, the anterior process of the palatine

moves medially when the buccal and opercular

cavities are expanded (e.g., when feeding), since

it is situated dorsal to the articulation of the

palatal arch with the skull. This medial movement

locks the cranial condyle of the maxilla in position,

which in turn prevents the posterior movement of

the premaxilla (since the articular process of the

premaxilla jams against the premaxillary condyle

of the maxilla). The mouth can thus be closed with

the premaxilla in the protruded position (were

the processes not present, the premaxillae would be

retracted during mouth closing—see Alexander,

1967, for details). In the triacanthoids, medial

movement of the palatal process would put some

pressure on the maxilla, but since none of the

above processes are present, this would be insufficient to lock them in position during closure of the

mouth.

Of the two subfamilies, the Hollardiinae are

apparently the most generalized (Tyler, 1968:31-

33). However, Tyler (1968:30, fig. 6) also indicates

in effect, that they, the triacanthids and the balistoids, form the sister group of the triacanthodins.

Subfamily TRIACANTHODINAE

Triacanthodes anomalus (Schlegel)

FIGURES 49-56

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figure 49: A 1, A 2«,

A 2P; see also Figure 68a of Hollardia).—The adductor mandibulae is well separated into two portions

by the path of ramus mandibularis V. The posterodorsal section (A 2a) originates from the anterodorsal face of the hyomandibular and from a

sheetlike aponeurosis covering the dorsal surface

of the section. Beneath the eye, A 1 begins to

develop, increasing in size as it passes anteriorly.

The fibers from A 1 grade into a tendon which

receives contributions from A 2P and A 3 ventrally.

This composite tendon then divides, the dorsal

part passing anterodorsally to insert near the medial

face of the cranial condyle of the maxilla, beneath

its articulation with the palatine, while the ventral

part inserts on the anteromedial face of the dentary

in the Meckelian fossa. The lateral portion of the

ventral fibers contributing to the tendon mentioned

above forms A 23, which originates from the dorsal
NUMBER 155

preopercle and quadrate and the anterior face of

the hyomandibular. The ventromedial section, A 3,

originates from the lateral faces of the quadrate,

syraplectic, and metapterygoid.

LEVATOR ARCUS PALATINI (Figure 49: L.A.P).—

The muscle originates from the ventral face of the

postorbital process of the sphenotic, and inserts on

the dorsal and anterodorsal faces of the hyomandibular. It is a pyramidal muscle, whose apex lies

dorsally.

DILATATOR OPERCULI (Figure 49: D.O.).—Origin is

from the ventrolateral sphenotic and pterotic and

the dorsal tip of the hyomandibular. The fibers

pass ventrolaterally to insert on the tip of the dorsal

process of the opercle. It is a conical muscle, with

the apex pointing ventrally.

LEVATOR OPERCULI (Figure 49: L.O.).—The muscle consists of two portions. The anterior part

originates from the ventrolateral face of the pterotic

and inserts on the dorsomedial face of the posterior

flange of the opercle. The posterior section arises

from the lateral pterotic and anteromedial supracleithrum and passes ventrally to insert on the

posteromedial flange of the opercle just behind the

insertion of the anterior part.

ADDUCTOR ARCUS PALATINI (Figure 49: A.A.P.).—

This parallel fibered muscle originates from the

ventrolateral surface of the parasphenoid and the

lateral prootic. It inserts on the dorsomedial faces

of the metapterygoid, mesopterygoid, and hyomandibular.

ADDUCTOR OPERCULI (Figure 50: AD.OP.).—Origin

is from the ventral face of the pterotic, the fibers

inserting on the dorsomedial face of the opercle.

MUSCLES OF THE HYOID REGION

INTERMANDIBULARIS (see Figure 65 of Hollardia,

win.).—This small muscle connects the halves of the

lower jaw, attaching to the dentaries just below the

Meckelian fossae.

PROTRACTOR HYOIDEI (Figure 49: PR.HY.).—Origin

is from the inner face of the dentary, both dorsal

and ventral to the intermandibularis. The fibers

pass posteriorly and split into left and right halves.

Each section inserts on the lateral face of the anterohyal as far back as the third branchiostegal ray.

HYOHYOIDEUS INFERIORIS (Figures 49, 50: HY.

IN.).—The muscle is relatively well developed, and

passes from a median ventral raphe to the anterolateral and ventral surfaces of the anterohyal. The

muscle attaches ventrally to the ventrohyals by a

pair of ligaments passing anterolaterally from the

anteromedial border of the fibers. These are similar,

although somewhat weaker, than those figured for

Hollardia (Figure 65).

HYOHYOIDEI ABDUCTORES (Figure 49: H.AB.).—

There are four sections of this muscle, one to each

of the ventral four branchiostegal rays. The section

to the first ray originates as a long tendon from the

posteroventral face of the ventrohyal, that to the

next ray from the base of the first ray. The two

following sections arise from the base of the second

ray. All insert on the medial faces of the rays distal

to their bases.

HYOHYOIDEI ADDUCTORES (Figure 49: H.AD.).—

The muscle passes between the dorsalmost four

branchiostegal rays and continues above them as a

thin layer of fibers in the membrane lining the

opercular cavity, fading out beneath the opercle

and subopercle. There is a fairly well-developed

section along the posterior border of the opercle in

the tissues of the opercular valve. Fibers also continue inward ventrally along the floor of the opercular cavity for a short distance.

STERNOHYOIDEUS (Figures 49, 50: STH.).—A welldeveloped muscle, consisting of three bundles of

fibers separated by myocommata. The posterolateral region is continuous with the anterolateral

fibers of the obliquus inferioris. Origin is from the

anteroventral deithrum and insertion mainly on

the posterior and lateral faces of the urohyal. The

dorsomedial fibers tend to pass dorsally rather than

anterodorsally. The more anterior of these fibers

attach to the fascia separating the halves of the

sternohyoideus, while the more posterior ones are

to a greater or lesser extent continuous with the

fibers of the sternobranchialis.

STERNOBRANCHIALIS (Figure 50: STB.).—The

muscle originates from the anteroventromedial face

of the cleithrum. It passes dorsally, the anterior fibers intermingling with those of the sternohyoideus,

and grades into a broad, flat aponeurosis which

fuses with that from the other side. The two sheets

then separate and divide into anterior and posterior

components. The latter passes dorsally, lateral to

the rectus communis, to insert on the ventral faces

of the third hypobranchial and fourth ceratobranchial. From the posteromedial face of the

anterior portion a tendon arises, fusing briefly
8

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

with its antimere before diverging to insert on the

ventral surface of the third hypobranchial. It

passes medial to the rectus communis. The rest of

the anterior sheet continues upward, lateral to the

rectus communis. to insert on the ventral surfaces

of the first three hypobranchials.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 50, 51:

PHC.E.).—Origin is from the anterodorsal face of the

medial region of the cleithrum, the fibers passing

dorsomedially to insert on the anteroventral face

of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 50, 51:

PHC.L).—The fibers arise from the anteromedial

face of the cleithrum and pass forward to insert on

the ventral border of ceratobranchial 5. The insertion is medial to that of the pharyngoclavicularis

externus.

OBLIQUI VENTRALES I-III (Figure 51: OBL.V.).—

These muscles pass between the ceratobranchials

and hypobranchials of the first three arches. The

first is small, the second being somewhat better

developed. The third muscle attaches to the ventral

process of the third hypobranchial. The more

posterior fibers of this section attach to the archshaped ligament between the left and right hypobranchial processes.

TRANSVERSI VENTRALES rv-v (Figure 51: TR.V.).—

The muscles pass transversely across the midline,

connecting the ventromcdial faces of the fourth and

fifth ceratobranchials, respectively.

RECTI VENTRALES I AND iv (Figure 51: RECT.V.).—

The first of these muscles connects the anterolateral

face of hypobranchial 1 to the posterolateral face

of the dorsohyal. Rectus IV arises from the ventral

face of ceratobranchial 4 and passes anteromedially

to attach to the posterior surface of the arch-shaped

ligament between the third hypobranchials.

RECTUS COMMUNIS (Figures 50, 51: R.COMM.).—

Origin is from the posterodorsolateral face of the

urohyal. The fibers pass posteriorly, the muscle becoming aponeurotic about the level of the third

hypobranchial. It inserts on the ventrolateral face

of ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI i-rv (Figure 50: L.EXT.).—

These four cylindrical muscles insert aponeurotically on the posterodorsal faces of the four epibranchials. They originate from the lateral prootic,

and a small part of the pterotic, increasing in size

while attaining a more lateral origin as one proceeds posteriorly in the series.

LEVATORES INTERNI II-III (Figure 52: L.INT.).—

Both muscles originate from the prootic. Levator

II inserts on the dorsomedial face of the infrapharyngobranchial 2, while levator III (which originates

more dorsolaterally on the prootic) inserts on the

anterodorsolateral face of the infrapharyngobranchial 3.

OBLIQUUS DORSALIS HI (Figure 52: OBL.D.).—The

muscle passes from the anterodorsal face of epibranchial 2 to the posterodorsal face of infrapharyngobranchial S.

OBLIQUUS POSTERIOR (Figure 52: OBL.P.).—The

muscle connects the anterodorsal face of ceratobranchial 5 to the posterodorsal face of ceratobranchial 4.

TRANSVERSI DORSALES II-III (Figures 50, 52: TR.

D.^.—The anterior muscle originates partly from the

ventrolateral surface of the parasphenoid and partly from a raphe with its antimere behind this. It

inserts on the dorsal face of epibranchial 2. The

posterior muscle arises from a raphe in the dorsal

midline and courses laterally to insert on the posterodorsal face of epibranchial 3.

RETRACTOR DORSALIS (Figure 52: D.RETR.).—This

is a well-developed muscle originating from the

ventrolateral surfaces of the basioccipital and the

first vertebra. It passes anteroventrally to insert on

the dorsal face of infrapharyngobranchial 3.

ADDUCTORS IV-V (Figures 50, 52: AD.).—Adductor IV is a small muscle connecting the medial

faces of the fourth epi- and ceratobranchials. Adductor V is also small, and passes from the anterodorsal tip of ceratobranchial 5 to the distal tip of

epibranchial 4. It lies lateral to the obliquus

posterior.

SPHINCTER OESOPHAGI (Figures 51, 52: s.o.).—

The fibers of the muscle surround the esophagus,

attaching mainly to the posteromedial faces of the

fifth ceratobranchials. In the ventral midline, it lies

dorsal to transversus ventralis V, and develops a

raphe at its extreme anterior margin. It is continuous across the dorsal midline, and is attached

anteriorly to epibranchial 4 by connective tissue.
NUMBER 155

MUSCLES OF THE PECTORAL GIRDLE

ABDUCTOR SUPERFICIALIS (Figure 49: ABD.S.).—

The fibers originate from the posteroventral face

of the cleithrum, and pass posterodorsally to insert

by a series of tendons on the dorsolateral bases of

the 12 principal fin rays.

ABDUCTOR PROFUNDUS (Figures 49, 50, 53: ABD.

P.).—Origin is from the posterior face of the

cleithrum and the anterior face of the coracoid.

The fibers pass dorsally to insert tendinously on the

lateral faces of the posteroventral flanges of the 12

principal fin rays and the lateral half of the base

of the vestigial fin ray.

ARRECTOR VENTRALIS (Figure 49: ARR.V.).—The

muscle originates just dorsal to the abductor superficialis on the cleithrum. It courses posterodorsally to insert tendinously on the base of the medial

half of the vestigial fin ray.

ADDUCTOR SUPERFICIALIS (Figure 53: ADD.S.).—

Origin is from the posterior face of the cleithrum

and the ventromedial scapula. The fibers insert

by a series of 12 tendons on the dorsomedial faces

of the principal fin rays. The more medial and

dorsal portion of the muscle serves the more ventral

fin rays, attaching at right angles to the longitudinal axes of the rays. The more ventral fibers attach

to the more dorsal rays with an increasingly parallel

orientation. The muscle has thus effectively "folded

under" itself.

ADDUCTOR PROFUNDUS (Figure 53: ADD.P.).—Origin is from the medial cleithrum and coracoid, the

muscle inserting tendinously on the ventromedial

flanges of the bases of the 12 principal fin rays.

ARRECTOR DORSALIS (Figure 53: ARR.D.).—The

muscle originates from the medial face of the scapula and cleithrum, and passes posterodorsally to

insert on the medial half of the vestigial fin ray.

CORACORADIALIS (Figure 53: COR.R.).—A small

muscle, arising from the dorsal face of the posterior

process of the coracoid, and inserting on the ventromedial face of the last (vend-almost) radial.

ADDUCTOR RADIALIS (see Figure 62 of Parahollardia, ADD.R. ;.—The fibers arise from the ventromedial faces of the middle two radials and insert

on the bases of the ventralmost two fin rays. It

courses at right angles to the coracoradialis, and lies

lateral to the adductor profundus.

PROTRACTOR PECTORALIS (Figure 50: P.P.).—Origin is from the ventrolateral pterotic just behind

the hyomandibular fossa, the fibers passing ventrally to insert on the anterodorsal face of the

cleithrum.

LEVATOR PECTORALIS (Figure 50: TR.).—The

muscle arises from the pterotic just behind the

protractor pectoralis. The fibers fan out to insert

on the medial face of the supracleithrum.

MUSCLES OF THE PELVIC GIRDLE

ARRECTOR DORSALIS PELVICUS (Figures 50, 53:

A.D.P.).—Origin is from the anterolateral face of

the anterior part of the pelvis, and is bordered

ventrally by the lateral flange of the bone. It inserts

on the anterolateral aspect of the pelvic spine,

dorsal to the articulation with the pelvis.

ARRECTOR VENTRALIS PELVICUS (Figure 53:

A.V.P.).—The muscle arises from the anteroventral

surface of the anterior part of the pelvis. It inserts

on the anterolateral aspect of the pelvic spine,

ventral to the articulation with the pelvis.

ADDUCTOR SUPERFICIALIS PELVICUS (Figures 50, 53:

A.S.P.).—Originating on the posteromedial face of

the anterior part of the pelvis, the fibers pass posterolaterally to insert on the dorsal surface of the

dorsal flange of the pelvic spine.

ADDUCTOR PROFUNDUS PELVICUS (Figure 53:

A.P.P.).—There are two slips of this muscle, which

originate from the dorsomedial face of the pelvis

posterior to the adductor superficialis pelvicus.

Each slip inserts on the dorsomedial surface of a

pelvic ray, the larger and more anterior section

inserting on the more anterior of the two rays.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORS ALES (Figures 49, 55a: INC.).—

The second to fourth dorsal spines and their

pterygiophores receive a sheet of muscle fibers

arising from the fascia overlying the epaxialis. The

inclinator to the sixth spine and those to the soft

dorsal fin rays are separate, inserting only on the

bases of the spine or ray. The muscles to the rays

are well developed, particularly anteriorly.

ERECTORES DORS ALES (Figures 49, 54, 55a:

EREC. )—All spines and fin rays receive an erector.

The fibers arise from the lateral faces of the

pterygiophores and associated neural spines, and

insert on the anterolateral bases of the spines or
10 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

rays. The first erector is extremely powerful and is

bipinnate. The size of these muscles in both the

spiny and the soft dorsal fins decreases posteriorly.

DEPRESSORES DORSALES (Figures 49, 54, 55a:

DEPR.).—All spines and rays receive a depressor,

which originates from the lateral pterygiophores

and neural spines in between the erectors. The

muscles are smaller than the erectors, and insert on

the posterolateral bases of the spines and rays. They

also decrease in size posteriorly in both fins.

SUPRACARINALIS ANTERIOR (Figures 49, 54: s.

ANT.).—Origin is from the lateral and dorsal faces

of the supraoccipital, the fibers inserting on the

anterodorsolateral face of the first pterygiophore of

the dorsal fin.

SUPRACARINALIS POSTERIOR (Figure 56: S.POST.).—

Fibers arise from the lateral surface of the last

pterygiophore of the dorsal fin, and course posteriorly. The muscle attaches to the dorsolateral tips

of the neural spines of the caudal vertebrae, terminating on the neural spine of caudal vertebra 10.

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES (Figure 556: INC.).—Each

anal fin ray receives an inclinator on the lateral

face of the fin base, which originates in the fascia

overlying the hypaxialis. The anterior muscles are

better developed than the posterior ones. There is

an additional, residual inclinator muscle originating in front of the first normal inclinator and

inserting on the ventrolateral face of the first anal

fin pterygiophore.

ERECTORES ANALES (Figure 556: EREC).—Each

fin ray possesses an erector, originating from the

lateral faces of the pterygiophores and haemal

spines and inserting on the anterodorsal base of the

ray.

DEPRESSORES ANALES (Figure 556: DEPR.).—These

muscles originate just posterior to the erectors and

insert on the posterolateral bases of the fin rays.

INFRACARINALIS ANTERIOR (Figures 49, 50, 53:

INF.A.).—Fibers arise from the posteroventral extremity of the cleithrum and fan out to insert on

the anterolateral face of the pelvis.

INFRACARINALIS MEDIUS (Figure 49: INF.M.).—

The muscle originates from the anteroventral margin of the first anal pterygiophore and inserts on

the dorsal face of the posterior tip of the pelvis. It

consists of two bundles of fibers separated by a

myocomma, just posterior to which is a small knot

of fibers passing dorsally to join the ventral surface

of the obliquus inferioris.

INFRACARINALIS POSTERIOR (Figure 56: INF.p.).—

Fibers arise from the posteroventral face of the last

anal pterygiophore and attach to the ventrolateral

tip of the haemal spine of caudal vertebra 10. The

medial fibers of the muscle attach to the lateral

tips of the haemal spines of the two intervening

vertebrae (8 and 9).

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 56a,6: INT.).—The muscle interconnects the caudal fin rays, with a section

inserting on the ventrolateral face of each of the

six dorsal rays and on the dorsolateral face of each

of the six ventral rays. The two strips of muscle

thus formed mingle between the rays on either side

of the midline.

HYPOCHORDAL LONCITUDINALIS (Figures 56a,6,:

H.L.).—Origin is from the lateral face of hypurals

1 and 2, the fibers coursing posterodorsally to insert on the lateral bases of the second to fourth

(D 2-4) dorsal fin rays.

FLEXOR DORSALIS (Figure 566: F.D.).—The muscle

originates from the lateral surfaces of the neural

spines and dorsolateral surfaces of the centra of

the ninth to eleventh caudal vertebrae, and the

dorsolateral face of the urostyle. The fibers pass

posterodorsally to insert on the lateral bases of

rays D 2-5.

FLEXOR DORSALIS SUPERIOR (Figure 56: F.D.S.).—

Origin is from the neural spines of the tenth and

eleventh caudal vertebrae, the fibers passing posteriorly to insert on the lateral base of D 6.

FLEXOR VENTRALIS (Figure 566: F.V.).—Fibers

arise from the posterolateral faces of the haemal

spines and ventrolateral surfaces of the centra of

the ninth to eleventh caudal vertebrae, and the

ventrolateral face of the urostyle. Fibers pass posteroventrally to insert on the bases of rays V 1-6.

FLEXOR VENTRALIS EXTERNUS (Figure 566: F.V.E.).—

The muscle originates from the posterolateral

faces of the haemal spines of caudal vertebrae 9-10,

and passes posteriorly to insert on the lateral bases

of rays V 1-2. It lies directly beneath the hypaxial

body musculature.
NUMBER 155 11

FLEXOR VENTRALIS INFERIOR (Figure 56: F.V.I.).—

Origin is from the posterolateral tips of the haemal

spines of caudal vertebrae 10-11. Insertion is on

the base of ray V 6.

TRANSVERSUS CAUDALIS (Figure 56c: TR.C).—This

fan-shaped muscle originates from the dorsolateral

face of hypural 5 and the posterolateral surface

of the urostyle. It courses posteroventrally beneath

the hypochordal longitudinalis to insert on the

dorsal base of ray V 1.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 49, 56a: EPAX.).—The epaxial

musculature consists of nineteen myomeres, all vertebrae except the urostyle thus being represented.

There are two major directions of the myocommata, and a third direction is present. anterodorsally. The first two merge in the posterior region

of the body, where they insert by a series of broad

aponeuroses on the lateral bases of rays D 1-6. The

aponeuroses to rays D 1-3 pass medial to the

hypochordal longitudinalis. Anteriorly, the mass of

the muscle attaches to the posterior surface of the

skull.

OBLIQUUS SUPERIORIS (Figures 49, 50, 56a: OBL.

s.).—This section forms the main mass of the hypaxialis, and consists of eighteen myomeres. It is

poorly developed anteriorly, where it attaches to

the extreme posterodorsal tip of the cleithrum.

(The anterior section probably contains part of

the lateralis superficialis, which usually forms a

thin sheet covering both epaxial and hypaxial

musculature near the anterior midline. The fibers

apparently always pass anteroposteriorly, with little

dorsal or ventral angulation. Owing to the extreme

difficulty of observing the nature of this subdivision

in preserved (or even fresh) material, it will not be

considered further. Suffice it to say that a detailed,

accurate description of the lateral body muscles in

general, and that of the lateralis superficialis in

particular, would require serial sectioning of the

material. Greene (1913), in his diagnosis of the

lateralis superficialis, relies on color and histological criteria.) The obliquus superioris broadens out

posteriorly, forming the dorsal and posterior borders of the abdominal cavity. It contributes fibers

to the compound section of the hypaxialis inserting

on the lateral bases of caudal rays V 1-6.

OBLIQUUS INFERIORIS (Figures 49, 56a: OBL.L).—

The anteroventral portion of this section arises

from the ventrolateral face of the cleithrum and the

posterolateral pelvis. The anterior fibers are continuous with the sternohyoideus, most of the fibers

behind this attaching to the anteroventral margin

of the postcleithrum. The anterodorsal fibers arise

from the fascia over the midline and epipleurals

and course anteroventrally to the posterodorsal surface of the postcleithrum. The fibers become increasingly horizontal posteriorly, and the section

separates somewhat from the obliquus superioris

before finally fusing with it in the peduncular

region. The fibers from this part attach to the bases

of caudal fin rays V 1-6. The muscle is made up of

sixteen myomeres, the more anterior of which are

parallel with the muscle fiber direction.

Tydemania navigatoris Weber

FIGURE 57

Many of the differences in musculature between

this and the preceding species result from the

more elongate form of Tydemania. The sections of

the adductor mandibulae are somewhat reduced in

dorsoventral extent. A 3 is absent, having either

fused with A 23 or having degenerated. The origin

of A 23 thus now includes the lateral faces of the

symplectic, mesopterygoid and metapterygoid. The

tendon of A 1 is better developed. The origin of

the dilatator operculi is reduced, while that of the

anterior part of the levator operculi is larger. Owing to the more dorsal position of the opercle and

the smaller size of the dilatator operculi, a hiatus

has appeared between that muscle and the anterior

portion of the levator operculi.

The intermandibularis is poorly developed, consisting of only a few fibers, and the hyohyoideus

inferioris is not as large as in T. anomalus. A few

fibers of the sphincter esophagi overlie the retractor

dorsalis. Origin of the adductor radialis is restricted

to the ventral face of the third radial, the fibers

inserting only on the ventralmost pectoral fin ray.

The adductor profundus pelvicus, which inserts

on the pelvic fin rays in T. anomalus, is absent in

all other members of the Triacanthodinae examined. The erectores and depressores dorsales serve

only the first three dorsal spines. In this species

and the remaining members of the subfamily, the

inclinatores dorsales are present only in the soft

dorsal fin.
12

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Macrorhamphosodes platycheilus Fowler

FICURES 58-59

The larger specimen had the mouth twisted some

55 degrees to the left, while that of the smaller

individual was twisted to a lesser extent to the

right. No differences that could be correlated with

the side to which the mouth was twisted were

found, except in the adductor mandibulae. Here

A 1 appears to have completely replaced A 2a, and

includes the anterior faces of the preopercle and

hyomandibular in its sites of origin. A 3 is absent.

In both examples a single tendon passes anteriorly

and splits into two smaller ones. One of these inserts on the anteroventromedial face of the dentary,

while the dorsal division attaches to the posteromedial face of the maxilla. The tendon to the

maxilla is divided into two sections on the side

to which the mouth is twisted, but not on the

opposite side.

Owing to the considerably modified snout, the

origin of the protractor hyoidei has shifted mainly

to the ventral faces of the interopercles and the

thick connective tissue surrounding them. The

origin extends a third of the way along the snout

before grading into a single medial tendon which

courses anteriorly between the interopercles to attach broadly to the ventromedial faces of the dentaries. The intermandibularis and hyohyoideus

inferioris are as described for Tydemania.

Figure 59 gives a general view of the branchial

arch muscles not originating on the arches themselves, and is included to illustrate topographical

differences too slight to be discussed in the text.

The adductor radialis originates only from the second radial, and inserts on the lowermost pectoral

ray. Inclinatores dorsales to the spiny dorsal fin are

absent, and only the first two spines have erector

and depressor muscles. The interradialis is better

developed, and the flexor dorsalis inserts on caudal

rays D 1-6. There is less continuity between the

sternohyoideus and the anteroventral component

of the obliquus inferioris, mainly because the

ventrolateral border of the cleithrum and the dorsolateral surface of the pelvis are very close to one

another.

Halimochirurgus centriscoid.es Alcock

FIGURE 60

The origin of the adductor mandibulae sections

is as for M. platycheilus. A single tendon passes

anteriorly, inserting only on the posteromedial face

of the dentary. The protractor hyoidei is similar

to that of M. platycheilus, but there is no connection to the dentary. Instead, the fibers fade out in

the connective tissue between the interopercles,

about halfway up the length of the snout. The

comments made in connection with M. platycheilus

for the remaining muscular systems also apply to

H. centriscoides.

Subfamily HOLLARDIINAE

Parahollardia line at a (Long ley)

FIGURES 61-63

The muscles of the cheek are very similar in

disposition and proportion to those described for

T. anomalus. The hiatus between the dilatator

operculi and anterior part of the levator operculi,

which was apparent in all the triacanthodins examined except T. anomalus, is present in the two

species of Hollardiinae dissected. The ligaments

attaching the hyohyoideus inferioris to the ventrohyal are somewhat better developed. The adductor

radialis inserts on the three ventralmost pectoral

rays. The levator pectoralis inserts more on the

dorsomedial surface of the cleithrum than on the

supracleithrum.

The arrector dorsalis pelvicus is virtually continuous with the infracarinalis anterior anteriorly,

being separated only by a myocomma. This applies

to the arrector ventralis pelvicus as well. Two

adductor profundus pelvicus muscles are present,

the section to the second ray passing ventrolaterally

as opposed to posteroventrolaterally. An adductor

superficial pelvicus originates from the dorsal pelvis between the two slips of the adductor profundus

pelvicus, and inserts on the tip of the posterodorsal

flange of the first pelvic ray.

The inclinatores dorsales do not form a continuous sheet anteriorly, and insert variously on the

pterygiophores and spine bases, the precise relationships differing on the left and right sides of the

fish. All the spines receive erector and depressor

muscles.

The infracarinalis medius consists of four myomeres separated by myocommata. The ventrolateral

surface of the first anal pterygiophore receives
NUMBER 155 13

fibers from two residual inclinatores anales, which

lie anterior to the first inclinator inserting on a

fin ray. The body and caudal fin muscles are as

was described for T. anomalus.

Hollardia hollardi Poey

FIGURES 64-65, 68a

The powerful tendon of the adductor mandibulae which inserts in the Meckelian fossa develops

a few muscle fibers on its dorsal surface. These pass

anterodorsally to insert along the medial face of

the dentary dorsal to the fossa. The adductor radialis consists of two muscle slips to the ventralmost

two pectoral rays.

The first pelvic fin ray receives an adductor

profundus pelvicus muscle, all other fin ray

muculature being absent.

Five inclinatores dorsales are recognizable, most of

them overlapping from the base of the spine onto

the surrounding pterygiophore. The last two spines

do not have erector and depressor muscles.

The infracarinalis medius is made up of two

sections (as in the other triacanthodids examined,

but not P. lineata) in the smaller (53 mm) fish,

and of three sections in the larger (92 mm) example. A single anterior residual inclinator analis is

present.

Other muscles are as for P. lineata, or, if not

mentioned in connection with that species, as

described for T. anomalus.

Summary of Triacanthodidae

Certain regions of the body are more prone to

variation than others. Among the triacanthodids

dissected, significant variations are found in the

adductor mandibulae, intermandibularis, protractor hyoidei, levator and dilatator operculi, adductor radialis, the muscles of the pelvic fin rays,

and the erector, depressor, and inclinator muscles

of the spiny dorsal fin. The last three of these

muscles involve numerical differences, and seem to

be following a reductive trend. Apart from those

outlined above, the triacanthodid muscle plan

appears to be rather stable, in spite of the modifications of the two long-snouted genera (Macrorhamphosodes and Halimochirurgus).

Myological Descriptions of Representative Triacanthids

The general body outline of this family is represented in Figure 2. One species from three out of

the four recognized genera was dissected. They are

fairly slender fishes, with a rather long snout region and a maximum body depth between the bases

of the dorsal and pelvic fins. The tapering caudal

peduncle ends in a lunate caudal fin. They are

evidently capible of some speed and, unlike other

tetraodontiforms (except possibly Triodon), use

the tail as the primary unit of propulsion (see

Wickler, 1963).

Triacanthids are relatively shallow-water fishes,

their food apparently being composed of soft- and

hard-bodied marine invertebrates. They are usually

considered to share a common ancestor with the

Triacanthodidae, but to be somewhat more

specialized.

Trixiphichthys weberi (Chaudhuri)

FIGURES 66, 67. 69-75

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figure 66; see also Figure 686 of Triacanthus biaculeatus: A 1, A 2, A

3).—The sections of this muscle are not well separated, particularly in the posterior region. A 1

arises partly from the thick ligamentous fascia

covering the muscle beneath the eye, and partly

from the anterodorsal face of the hyomandibular

(a flange of which overlies the posterodorsal region

of the muscle). A small portion of this section

inserts on the dorsomedial face of the maxilla. The

A 2 section originates from the dorsal and lateral

quadrate and preopercle, and the anteroventral

hyomandibular. It forms a broad sheetlike tendon

anteriorly, which receives a substantial contribution

from A 1, and inserts in the Meckelian fossa in

the dentary. A 3 is possibly the most distinct section, and originates from the lateral quadrate and

preopercle. It lies medial to the tendinous plate

in the middle of the adductor mandibulae, and

joins the tendon to the Mecklelian fossa anteriorly.

LEVATOR ARCUS PALATINI (Figure 66: L.A.P.).—

The muscle is fairly small, and conical in shape.

It originates from the ventral face of the postorbital

process of the sphenotic and inserts on the antero-
14 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

dorsal face of the hyomandibular, including the

flange overlying section A 1 of the adductor

mandibulae.

DILATATOR OPERCULI (Figure 66: D.O.).—Origin

is from the sphenotic-pterotic suture region, the muscle coursing ventrally to insert on the tip of the

dorsal process of the opercle. It is relatively well

developed.

LEVATOR OPERCULI (Figure 66: L.O.).—The muscle

consists of two sections. The anterior portion originates from the pterotic and inserts on the dorsomedial flange of the opercle. The posterior part

arises from the dorsomedial face of the supracleithrum, and inserts just behind the anterior portion

on the dorsomedial opercle.

ADDUCTOR ARCUS PALATINI (Figures 66, 67:

A.A.P.).—Origin is from the lateral surface of the

prefrontal and the ventral flange of the parasphenoid. It inserts on the dorsomedial faces of the

mesopterygoid, metapterygoid, and hyomandibular.

The muscle is well developed, and extends anterior

to the orbit. Here the origin of the fibers becomes

relatively more dorsal than the insertion, so that

the fibers pass anteroventrolaterally.

ADDUCTOR OPERCULI (Figures 69, 71: AD.OP.).—

Fibers originate from the ventral surface of the

pterotic just behind the origin of the levatores

interni. The muscle courses ventrolaterally to insert on the dorsomedial face of the opercle.

MUSCLES OF THE HYOID REGION

INTERMANDIBULARIS.—This is a small muscle connecting the halves of the lower jaw. It attaches to

the dentary below the Meckelian fossa, just anterior

to the quadrate.

PROTRACTOR HYOIDEI (Figure 66: PR.HY.).—Origin

is from the lower jaw both dorsal and ventral to the

intermandibularis, the fibers passing posteroventrally. It separates into two halves in front of the

ventrohyal, and inserts on the lateral anterohyal. It

also overlies the ventral two branchiostegal rays,

some fibers arising from the lateral face of the

third ray.

HYOHYOIDEUS INFERIORIS (Figure 66: HY.IN.).—

The muscle arises from the ventrolateral face of the

anterohyal, lying for the most part beneath the

first two branchiostegal rays, but with a small section overlying the base of the first ray. It lies medial

to the protractor hyoidei, and arises from a midventral raphe with its antimere. The anterior face

of each side gives rise to a short ligament which

passes anteromedially to attach to the ventrohyal.

HYOHYOIDEI ABDUCTORES (Figure 66: H.AB.).—

There are four sections of this muscle, which insert

on the anteromedial faces of the ventral four

branchiostegal rays. The first muscle is well developed, and originates from the posterior face of

the ventral flange of the ventrohyal. The second

muscle arises from the base of the first ray, the

two dorsal muscles originating from the fascia

covering the bases of the first two rays.

HYOHYOIDEI ADDUCTORES (Figure 66: H.AD.).—A

well-developed muscle, interconnecting the four

dorsalmost branchiostegal rays. It continues dorsally, but soon fades out in the connective tissue

beneath the opercle and subopercle. It also continues inwards on the floor of the opercular cavity

for a short distance.

STERNOHYOIDEUS (Figures 66, 69: STH.).—The

muscle originates from the anterolateral face of the

ventral region of the cleithrum. In the extreme

anteroventral area there may be some fusion of

fibers from the two sides of the body. The posteroventrolateral fibers are continuous with the obliquus inferioris. The muscle, which is made up of

three myomeres, inserts on the lateral, posterior,

and ventral surfaces of the urohyal.

STERNOBRANCHIALIS (Figures 69, 70: STB.).—Origin is from the anteroventral cleithrum. The fibers

pass dorsally, and form a broad, sheetlike aponeurosis which fuses briefly with that of the opposite

side before diverging again. The sheet then divides

into a large anterior section and a smaller posterior

part. The former inserts on the posterodorsal

urohyal and the three hypobranchials. The posterior sections cross over to the ventral midline and

insert on the fourth ceratobranchial of the other

side. The aponeurosis from one side passes through

the middle of the aponeurosis of the other side in

the course of this crossing over. The anterior

aponeurosis is thickest in the region of the junction

between the first and second hypobranchials.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figure 69:

PHC.E.).—Fibers arise from the anterodorsal face

of the cleithrum and pass slightly posterodorsally

to insert on the ventrolateral face of the ceratobranchial 5.
NUMBER 155 15

PHARYNGOCLAVICULARIS INTERNUS (Figures 69, 70:

PHC.I.).—The muscle passes anteriorly from its origin on the anteromedial face of the cleithrum. It

splits into a series of tendons (of which the ventralmost is largest) which insert on the ventral surface

of ceratobranchial 5.

OBLIQUI VENTRALES I—m (Figures 69, 70: OBL.

v.).—The oblique muscles connect the ventral surfaces of the cerato- and hypobranchials of the first

three arches. Obliquus I is well developed. Part of

obliquus III inserts directly on the third hypobranchial. The most ventral fibers contribute to a

ligament which passes anteriorly to join that from

the other side and attach to the posterodorsal face

of the urohyal.

TRANSVERSI VENTRALES IV-V (Figure 70: TR.V.).—

These two muscles connect the anteromedial faces

of the fourth and fifth pairs of ceratobranchials

across the ventral midline.

RECTI VENTRALES I, ii, AND iv (Figures 69, 70:

RECT.V.).—The first of these muscles connects the

posterolateral face of the dorsohyal to the anterolateral face of hypobranchial 1, the second passing

from the dorsolateral surface of the urohyal to the

ventral region of ceratobranchial 2. Rectus IV

arises from the anteroventromedial face of ceratobranchial 4 and passes anteromedially to attach to

the arch-shaped ligament between the ventral processes of the third hypobranchials. There is a partial

crossing over of the more medial fibers in this

region.

RECTUS COMMUNIS (Figure 70: R.COMM.).—The

muscle originates from the posterodorsal urohyal.

It passes posteriorly, and grades into a tendon at

the level of the third hypobranchials. It inserts on

the anterolateral surface of ceratobranchial 5,

lying lateral to the sections of the pharyngoclaviculares.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I-IV (Figure 69: L.EXT.).—

This series of four muscles originates from the

lateral surface of the prootic. The muscles become

larger, and have a more lateral origin as they pass

posteriorly in the series. They insert aponeurotically on the posterodorsolateral faces of epibranchials 1-4, the second levator having a small inner

connection to epibranchial 3.

LEVATORES INTERNI II-III (Figure 71: L.INT.).—

These muscles originate from a depression in the

posterodorsal surface of the prootic. Levator II,

which has a slightly more lateral origin, inserts on

the dorsomedial face of infrapharyngobranchial 2,

while levator III inserts on the dorsolateral face

of infrapharyngobranchial 3.

OBLIQUUS DORSALIS HI (Figure 71: OBL.D.).—The

muscle passes from the dorsal surface of epibranchial 3 to the dorsomedial face of infrapharyngobranchial 3.

OBLIQUUS POSTERIOR (Figure 71: OBL.P.).—The

fibers connect the anteromedial face of ceratobranchial 5 to the posterior face of epibranchial 4.

TRANSVERSI DORSALES II-III (Figures 69, 71: TR.

D.).—The anterior of these two muscles originates

from the ventrolateral face of the parasphenoid,

and courses laterally to insert on the dorsolateral

face of epibranchial 2. A few of the more posterior

fibers may fuse with their antimeres. Transversus

III arises from a middorsal raphe with its antimere,

and passes laterally to insert on the posterodorsal

face of epibranchial 3 beneath obliquus dorsalis III.

RETRACTOR DORSALIS (Figure 71: D.RETR.).—Origin is from the ventrolateral surface of the first

vertebra, although a few of the more posterior

fibers may arise from the anterodorsal tip of the

swim bladder. It passes anteroventrally to insert on

the posteromedial face of infrapharyngobranchial 3.

ADDUCTORES IV-V.—The anterior muscle connects

the dorsomedial face of ceratobranchial 4 to the

ventrolateral face of epibranchial 4. Adductor V

arises from the anterodorsal tip of ceratobranchial

5 and passes anterodorsally to the posterolateral

face of epibranchial 4, lateral to the obliquus

posterior.

SPHINCTER OESOPHAGI (Figures 70, 71: s.o.).—

Ventrally the fibers attach to the ventromedial

faces of the fifth ceratobranchials, there being a

midventral raphe. The fibers pass dorsally around

the esophagus, attached to the fifth ceratobranchials, the more dorsal fibers attaching to the fourth

epibranchials. A small section overlaps the retractor

dorsalis anterodorsally.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 66: ABD.S.).—

Fibers originate from the posterior rim of the

cleithrum and course posterodorsally to insert on
16 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

the dorsolateral bases of the 13 principal fin rays.

ABDUCTOR PROFUNDUS (Figures 66, 69: ABD.P.).—

The muscle originates beneath the abductor superficialis from the posteroventrolateral deithrum and

the anterolateral coracoid. It inserts on the posterolateral bases of both the principal and the vestigial

fin rays.

ARRECTOR VENTRALIS (Figure 66: ARR.V.).—The

fibers arise from the posterior face of the cleithrum

just above those of the abductor superficialis, and

insert on the lateral base of the medial half of the

vestigial fin ray.

ADDUCTOR SUPERFICIALIS (Figure 73: ADD.S.).—

Origin is from the posteromedial face of the cleithrum. The fibers of the dorsomedial part of the

muscle serve the more ventral fin rays, those of the

more superficial, ventral section inserting on the

more dorsal fin rays. Tendons insert on the dorsomedial faces of the principal rays a little distal to

their bases.

ADDUCTOR PROFUNDUS (Figure 73: ADD.P.).—The

muscle originates from the medial faces of the

coracoid and cleithrum ventral to the adductor

superficialis and inserts on the ventromedial bases

of the principal fin rays.

ARRECTOR DORSALIS (Figure 73: ARR.D.).—Fibers

arise from the medial face of the cleithrum between the two adductor sections. Insertion is on

the dorsomedial face of the base of the vestigial fin

ray.

CORACORADIALIS (Figure 73: COR.R.).—The muscle

originates from the fascia covering the adductor

profundus and from the posteromedial coracoid.

The fibers insert on the posteromedial process of

the fourth radial.

ADDUCTOR RADIALIS.—This small muscle originates from the medial faces of the middle two

radials and passes posteriorly to insert on the bases

of the ventralmost two pectoral fin rays.

PROTRACTOR PECTORALIS (Figure 69: P.P.).—Fibers

arise from the ventrolateral region of the pterotic

and insert on the anterodorsal face of the cleithrum.

MUSCLES OF THE PELVIC GIRDLE

ARRECTOR DORSALIS PELVICUS (Figure 69: A.D.P.).—

Origin is from the lateral surface of the anterior

region of the pelvis, the fibers inserting on the

anterodorsolateral face of the pelvic spine. The

muscle is bipinnate.

ARRECTOR VENTRALIS PELVICUS.—The muscle is

only partially separated from the infracarinalis

anterior, and originates from the anteroventral

face of the pelvis. Insertion is on the anteroventrolateral face of the pelvic spine.

ADDUCTOR SUPERFICIALIS PELVICUS (Figure 69:

A.S.P.).—The muscle originates from the posteromedial face of the cleithrum and passes posteroventrally and somewhat laterally to insert on the

posterodorsal face of the dorsal flange of the pelvic

spine.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORSALES (Figures 66, 74: INC.).—

There are three inclinators to the spiny dorsal fin,

arising in the fascia over the epaxialis and inserting on the posterolateral bases of the first three

pterygiophores. Each fin ray of the soft dorsal fin

receives an inclinator attaching to its lateral base,

the fibers arising in the spaces between the lateral

flanges of the pterygiophores. The inclinators to

the spiny dorsal fin are flat and fan-shaped, those

to the soft dorsal fin are smaller and more conical.

ERECTORES DORSALES (Figures 72, 74: EREC).—The

first five spines of the dorsal fin have erector muscles, of which the powerful, bipinnate muscle to

the first spine is very much the largest. The

erectors of the spiny fin originate from the lateral

faces of the pterygiophores (including the exoccipital in the case of the first muscle), while those

to the soft fin arise from the lateral faces of the

pterygiophores and the neural spines.

DEPRESSORES DORSALES (Figures 66, 72, 74:

DEPR.).—Depressors serve the first five spines and all

the fin rays, inserting on the posterolateral bases

of these elements. Origin is from the lateral faces

of the pterygiophores for the muscles serving the

spines, and also includes the lateral faces of the

neural spines for the sections to the fin rays.

SUPRACARINALIS ANTERIOR.—The muscle is short

and powerful. It originates from the posterior face

of the supraoccipital and inserts on the anterior

face of the first basal pterygiophore of the spiny

dorsal fin.

SUPRACARINALIS POSTERIOR (Figure 756: S.POST.).—

The muscle arises from the posterior face of the

last dorsal fin pterygiophore and passes posteriorly,

attaching to the tips of the neural spines of the

seventh to tenth caudal vertebrae, ending on the

tenth neural spine.
NUMBER 155 17

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES.—Each anal fin ray possesses an inclinator muscle, originating in the fascia

overlying the hypaxial body musculature and inserting on the lateral base of the ray. An anterior,

residual inclinator muscle is present, inserting on

the ventrolateral base of the first anal fin pterygiophore.

ERECTORES ANALES.—Each fin ray has an erector

muscle, which originates from the lateral face (s) of

the pterygiophore, haemal spine, or both, and

inserts on the anterolateral base of the ray.

DEPRESSORES ANALES.—The depressor muscles

have the same sites of origin as the erectors, and

insert on the posterolateral bases of all the fin rays.

INFRACARINALIS ANTERIOR (Figure 69: INF.A.).—

The muscle arises from the -ventromedial face of

the posterior coracoid and from the fascia attached

to the posteromedial face of the cleithrum. It

inserts on the anteroventral face of the pelvis.

INFRACARINALIS MEDIUS (Figure 66: INF.M.).—The

fibers connect the posterodorsal face of the pelvis

with the ventrolateral tip of the first anal pterygiophore.

INFRACARINALIS POSTERIOR (Figure 756: INF.P.).—

The fibers arise from the posterior face of the last

anal fin pterygiophore, and course posteriorly. The

muscle ends on the anterior tip of the haemal spine

of the tenth caudal vertebra, the fibers attaching

to the haemal spine tips of the intervening vertebra

(7-9).

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 75a: INT.).—The muscle

is made up of slips of fibers arising from the ventral

bases of the dorsal rays and the dorsal faces of the

ventral rays, the resulting muscle bundles intermingling in the midlateral line. All fin rays possess

a slip of this muscle.

PROXIMALIS (Figure 756: PROX.).—The muscle

originates from the lateral face of the centrum of

the tenth caudal vertebra. It passes posteriorly to

insert on the lateral flange of the ural centrum.

(The flange arises from the posterior region of

the centrum, and continues posteriorly onto the

anterior part of the fused third and fourth hypurals.)

HYPOCHORDAL LONGITUDINALIS (Figure 75a:

H.L.).—Origin is from the lateral surface of the

fused lower hypurals (1 and 2). The fibers pass

posterodorsally to insert on the lateral bases of rays

D 3-4, lateral to the epaxialis.

FLEXOR DORSALIS (Figure 756: F.D.).—The muscle

arises from the lateral faces of the penultimate and

ural centra and the anterolateral region of fused

hypurals 3 + 4. Insertion is on the dorsolateral

bases of rays D 1-6.

FLEXOR DORSALIS SUPERIOR (Figure 75: F.D.S.).—

The muscle originates from the lateral and dorsal

faces of the neural spines and centra of the ninth

to eleventh caudal vertebra. It inserts tendinously

on the anterolateral base of ray D 6.

FLEXOR VENTRALIS (Figure 75: F.V.).—Origin is

from the posteroventral face of the flange of the

ural centrum, the ventrolateral faces of the ural

centrum, and the fused hypurals 1+2 . The muscle

inserts on the lateral bases of rays V 1-6.

FLEXOR VENTRALIS EXTERNUS (Figure 756: F.V.

E.).—The fibers arise from the anteroventral surface of the eleventh caudal vertebra and insert on

the lateral bases of rays V 1-2.

FLEXOR VENTRALIS INFERIOR (Figure 75: F.V.I.).—

The muscle originates from the lateral and ventral

faces of the ninth to eleventh caudal vertebra, and

inserts on the anteroventral base of ray V 6.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 66, 75a: EPAX.).—Two main

directions of the myocommata are evident, with a

third anterodorsally. In the anterior region, the

fibers attach to the posterior face of the skull.

Posteriorly the muscle fibers become intermingled

with aponeuroses, which gives rise to a tough

fascia covering the intrinsic caudal fin musculature.

Beneath this fascia the fibers grade into aponeuroses

which insert on the lateral bases of caudal rays

D 2-6, and lie, for the most part, medial to the

hypochordal longitudinalis.

OBLIQUUS SUPERIORIS (Figures 66, 69, 75a; OBL.

s.).—The section is poorly developed anteriorly, but

forms the main mass of the hypaxial body musculature posteriorly. In the region of the caudal

peduncle, the fibers become intermingled with

aponeuroses, which join those of the epaxialis to

give rise to the fascia mentioned above. Beneath

this, the fibers mingle with those of the obliquus

inferioris and grade into a series of aponeuroses
18 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

inserting on the lateral bases of rays V 1-6. Anteroventrally, some fibers arise from the facia overlying

the dorsal surface of the swim bladder. In the

extreme anterior region, the fibers attach to the

posterodorsal tip of the cleithrum.

OBLIQUUS INFERIORIS (Figure 66: OBL.I.).—Anteroventrally this section originates from the posterior

coracoid and posterior and lateral cleithrum, being

continuous anterolaterally with the sternohyoideus.

Most of these fibers insert on the anteroventral face

of the postcleithrum. Above this, fibers arise from

the midline at the level of the epipleurals and

pass ventrally to attach to the posterodorsal face

of the postcleithrum. The fibers become more

horizontally oriented in the posterior region, and

begin to mingle with those of the obliquus superioris at about the level of the anal fin, giving rise

to the aponeuroses to the caudal fin rays.

SPINALIS (Figure 72: SPIN.).—This muscle originates from the posterior face of the strutlike first

dorsal pterygiophore and passes posteriorly. It

soon grades into a long tendon which attaches to

the dorsolateral tips of the neural spines of the

second to fifth vertebrae. It is a bilaterally symmetrical muscle, and may represent the first

myomere.

Triacanthus biaculeatus (Bloch)

FIGURES 686, 76

There are few differences in the musculature.

Owing to the shorter snout of T. biaculeatus, the

overall shape of the adductor mandibulae is somewhat different (compare Figures 66 and 76), although the subdivisions are the same. The hyohyoidei adductors are better developed, some fibers

continuing dorsally behind the opercle to attach to

the supracleithrum. There are only two inclinator

dorsales to the spiny dorsal fin, which insert on the

lateral bases of the first two basal pterygiophores.

The spinalis is less well developed than in the

preceding species.

Tripodichthys oxycephalus (Sleeker)

FIGURE 77

The adductor arcus palatini is well developed,

being of quite substantial thickness beneath the

eye. The adductor operculi possesses a small anterior section which inserts on the posterodorsomedial

face of the hyomandibular. The hyohyoidei adductores are as described for T. biaculeatus, and the

ventralmost muscle of the hyohyoidei abductores

is well developed. There is no fusion of the fibers

of the sternohyoideus with those of the sternobranchialis. The aponeurotic sheet of the latter

muscle is continuous, and the portion inserting on

ceratobranchial 4 does not cross over with the

section from the other side. The adductor radialis

is very small and inserts only on the lowermost

pectoral ray.

There are four inclinatores dorsales, one to the

dorsolateral region of each pterygiophore. The

lateral flange on the ural centrum is less well

developed, so that the proximalis is scarcely visible

superficially. The flexor dorsalis does not have a

section to ray D 6.

Summary of Triacanthidae

Little variation is apparent in the single species

of each of the three genera examined. The inclinatores dorsales of the spiny dorsal fin do vary considerably, however, but these muscles appear to

have no functional significance since they are very

small and insert on the bases of the dorsal pterygiophores. There is also some variation in the extent

of development of the hyohyoidei adductores and

the adductor radialis, but the family is basically

conservative.

Myological Descriptions of Representative Balistids

The general body outline of this family is represented in Figure 3. Representative species from

five of the eleven genera recognized by Berry and

Baldwin (1966) were dissected. Members of this

family are very conservative in body form. They

possess a terminal mouth armed with incisiform

teeth (and two canines in Odonus). The snout

region is long, with the eye high up on the head.

The first dorsal fin consists of three spines, the

heavy, large first spine being locked in position by
NUMBER 155 19

the small second spine. Pelvic fins are reduced to

rudiments at the end of a long, shaftlike pelvic

bone (Tyler, 1962b). The soft dorsal and anal fins

are well developed, consisting of many rays. A

slightly narrowed caudal peduncle ends in a double

emarginate or rounded caudal fin, although other

shapes do occur. Scales are large and heavy, and

may possess longitudinal ridges (for the functional

significance of which, see Wahler and Wahler,

1964). Balistids occur mainly on and around coral

reefs, and are diurnal. A few oceanic forms exist,

primarily in tropical waters. The food of the family is comprised of both soft- and hard-bodied

marine invertebrates (often corals), although certain species show a preference for plant material

(see, for example, Melichthys, in Randall, 1967).

Fast swimming is accomplished by synchronous

side-to-side beating of the dorsal and anal fins, the

caudal fin being used for bursts of speed. Slow

swimming is achieved by undulations of the dorsal

and anal fins. When stationary, the beat passes

posteriorly in the dorsal fin and anteriorly in the

anal fin. This can be shown by a parallelogram of

forces to help in counteracting the larger gravitational forces acting on the head region.

Balistids are supposed to be derived from triacanthid-like fishes, and to have "given rise" to the

Monacanthidae. Using a more modern approach,

they are apomorph relative to the former, and represent the plesiomorph sister group of the latter.

However, recent work (Tyler, 1970a:31) indicates

that the ostracioids may have to be included somewhere in this lineage, probably sharing a common

ancestor with the balistoids.

Batistes vetula Linnaeus

FIGURES 78-85

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 78, 79; and Figure 87a of Balistapus undulatus: A la A 13,

A 2a, A 23, A 2Y, A 3).—Section A 1 is separable

into two portions, one superficial (A la) and the

other deep (A 13). The former originates from

the lateroventral faces of the ethmoid and prefrontal, the infraorbital ligament and the anterodorsal face of the hyomandibular. A 13 is small,

and originates from the lateral metapterygoid and

mesopterygoid, being completely overlain by A

la. The two sections insert by a common tendon on

the posteroventral and ventromedial faces of the

maxilla. A 2 is also subdivided into two parts. A

2a is superficial and originates from the lateroventral ethmoid, the prefrontal, the infraorbital

ligament and the lateral hyomandibular. It is

separated from A 23 by the path of ramus mandibularis V, which emerges beneath the maxilla. The

section largely overlaps the subdivisions of A 1,

and also covers the more dorsal portion of A 23.

The latter section originates from the anterior hyomandibular, anterodorsal preopercle, and the

lateral metapterygoid. A 2v develops along the

ventrolateral extent of the preopercle. The sections

of A 2 insert broadly on the posterodorsomedial

face of the dentary, with some fibers of the first

two sections inserting on the maxillomandibular

ligament. A deep section, arising from the lateral

faces of the symplectic, quadrate, and metapterygoid appears to represent A 3. It fuses with the

tendon of A 23 anteriorly.

LEVATOR ARCUS PALATINI (Figure 78: L.A.P.).—

The muscle is fairly small, and originates from the

ventral face of the orbital process of the sphenotic

and the anterodorsal pterotic. The fibers pass anteroventrally to insert on the anterodorsal face of

the hyomandibular.

DILATATOR OPERCULI (Figure 78: D.O.).—Normally in the shape of an inverted triangle, this

muscle has inverted its shape anteriorly, the somewhat tendinous apex arising from the orbital process of the sphenotic. Some of the medial fibers are

continuous with the posterolateral fibers of the

levator arcus palatini. The more posterior fibers

arise from the ventrolateral face of the sphenotic.

Insertion is along the dorsolateral face of the

opercle.

LEVATOR OPERCULI (Figure 78: L.O.).—Origin is

from the anteroventrolateral pterotic and the anterior supracleithrum, the fibers inserting on posterodorsolateral face of the opercle.

ADDUCTOR ARCUS PALATINI (Figure 79: A.A.P.).—

The fibers arise from the anterolateral ethmoid and

the lateral parasphenoid in front of the orbit. The

more anterior fibers course in an increasingly anteroventrolateral direction. These fibers are anterodorsally continuous with the anteroventral fibers of

the retractor arcus palatini. Insertion is on the
20 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

medial and dorsal faces of the mesopterygoid,

metapterygoid, and the hyomandibular.

RETRACTOR ARCUS PALATINI (Figures 78, 79:

R.A.P.).—The muscle originates from the ventral

surface of the lateral flange of the ethmoid, the

lateral face of that bone, and the lateral parasphenoid. It consists of two subsections. The more

anterior, superficial fibers insert on the shaft of

the palatine and the ectopterygoid. From the dorsal

process of the ectopterygoid, a tendinous fascia

passes back to below the prefrontal, separating the

subsections completely posteriorly. The posteroventral subsection is covered by a thick fascia, to

which many of the fibers attach. It inserts on the

dorsal faces of the mesopterygoid and metapterygoid. The fibers mingle with those of the adductor

arcus palatini anteroventrally and those of the

dorsal subsection anterodorsally. Both subsections

are served by the same branch of the ramus buccalis

that serves the adductor arcus palatini.

ADDUCTOR OPERCULI (Figure 80: AD.OP.).—Origin

is from the anterolateral pterotic and lateral

prootic. The fibers pass anteroventrolaterally to

insert on the dorsomedial face of the opercle.

ADDUCTOR HYOMANDIBULAE (Figure 80: A.H.).—

The muscle originates behind and above the adductor operculi from the anteroventrolateral faces

of the pterotic and prootic. It inserts on the dorsomedial face of the hyomandibular, immediately below the articulation with the skull.

MUSCLES OF THE HYOID REGION

INTERMANDIBULARIS.—Lying immediately behind

the symphysis of the halves of the lower jaw, this

muscle (which is wholly dorsal to the protractor

hyoidei) connects the posterodorsomedial faces of

the left and right dentaries.

PROTRACTOR HYOIDEI (Figure 78: PR.HY.).—There

appear to be two sections of this muscle. A superficial division originates completely from the skin

and joins the deeper section before inserting on

the posteroventral margin of the lower jaw. The

larger inner portion originates almost entirely from

the lateral faces of the branchiostegal rays and the

anterohyal. There is some separation into three

longitudinal bundles posteriorly. The more ventral

fibers meet their artimeres in the ventral midline.

HYOHYOIDEUS INFERIORIS (Figure 78: HY.IN. )

The fibers arise from a midventral raphe underlying the anteroventral region of the urohyal and

pass dorsolaterally to insert along the ventral face

of the anterohyal.

HYOHYOIDEI ABDUCTORES (Figure 78: H.AB.).—The

muscles serve the ventral five branchiostegal rays.

The muscle to the first ray is much enlarged and

sheetlike. The fibers from the other four sections

join that from the first ray and attach anteriorly

to the ventromedial faces of the anterohyal, dorsohyal, and ventrohyal.

HYOHYOIDEI ADDUCTORES (Figure 78: H.AD.).—

The muscle is in the form of a continuous sheet

covering the wall of the opercular cavity. Fibers

arise from the fascia over the sternohyoideus and

sternobranchialis and pass dorsolaterally, fading out

in the connective tissue beneath the opercle and

subopercle. The branchiostegal rays are buried in

the same connective tissue as the muscle fibers, but

there is little direct attachment.

STERNOHYOIDEUS (Figures 78, 80: STH.).—The

posterolateral fibers are continuous with the anterolateral fibers of the obliquus inferioris. The more

medial fibers arise from the anteroventral face of

the cleithrum. A partially separated bundle of

fibers originates from the anteroventral tip of the

cleithrum and passes almost dorsally to the posteroventral tip of the urohyal. The muscle inserts

broadly on the urohyal, with some attachment to

the posteroventromedial face of the ventrohyal.

STERNOBRANCHIALIS (Figures 80, 81: STB.).—The

muscle originates from the anteroventral face of

the cleithrum, and passes vertically upward to

split into three sections. The anteriormost inserts

on the posteroventral tip of the urohyal, the middle

section inserting on the ventromedial face of

hypobranchial 3. The third section joins its antimere ventral to the rectus communis.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 80, 81:

PHC.E.).—Originating from the cleithrum immediately behind the sternobranchialis, the muscle

courses posterodorsally to insert on the anteroventral face of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 80, 81:

PHC.I.).—The muscle originates from the anteromedial face of the cleithrum. It passes anteriorly

to insert on the ventromedial bases of ceratobranchials 4 and 5.
NUMBER 155 21

OBLIQUI VENTRALES I-III (Figure 81: OBL.V.).—

These muscles connect the ventral faces of the

ceratobranchials and hypobranchials of the first

three arches. In the case of obliquus HI, most of

the fibers from the ceratobranchial attach to the

arch-shaped ligament between the ventral processes

of the third hypobranchials, the section actually

inserting on the ventral process of hypobranchial

3 being fairly distinct.

TRANSVERSI VENTRALES IV-V (Figure 81: TR.V.).—

The anterior muscle connects the anteroventromedial faces of the fourth ceratobranchials across the

ventral midline. There are two sections to the posterior muscle. The anterior of these lies between the

extreme anteroventromedial tips of the fifth ceratobranchials and is small. There is a small hiatus

between it and the posterior section, which lies

ventral to the sphincter oesophagi.

RECTI VENTRALES I, ii, iv (Figures 80, 81: RECT.

v.).—The first rectus joins the anteroventrolateral

face of ceratobranchial 1 to the posterodorsal face

of the dorsohyal. Some of the posteromedial fibers

are continuous with those of obliquus ventralis I.

Rectus II arises from the dorsolateral face of the

urohyal and attaches to the posterolateral face of

ceratobranchial 2. Rectus IV is represented by two

sections. The more ventral one arises from the ventral face of ceratobranchial 4 and passes anteromedially to attach to the posterior face of the

arch-shaped ligament between the third hypobranchial processes. The other section arises from the

dorsolateral face of ceratobranchial 4 and attaches

to the dorsomedial face of hypobranchial 3. This

latter muscle is apparently a derivative of obliquus

ventralis III.

RECTUS COMMUNIS (Figures 80, 81: R.COMM.).—

Origin is from the dorsolateral urohyal. The fibers

pass posteriorly, grading into an aponeurosis at

about the level of the third hypobranchial. The

tendon lies medial to the pharyngoclavicularis

externus and lateral to the pharyngoclavicularis

internus, and inserts on the ventrolateral face of

ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I-V (Figure 80: L.EXT.).—The

first four leva tors originate from the ventral surface of the prootic shelf and pass ventrally to the

dorsolateral faces of epibranchials 1-4. The muscle

to the third arch is not well developed. A fifth

levator is present, inserting on the dorsal tip of the

fifth ceratorbranchial, the more anterior fibers

fusing with the posterior region of levator IV. This

muscle appears to be divided into two sections by

a myocomma, which seems to cast aspersions on a

theory postulating its development solely from

levator IV.

LEVATORES INTERNI II-III (Figure 82: L.INT.).—

These muscles originate one on either side of the

facial foramen on the ventral surface of the

prootic. The anterior muscle inserts on the dorsomedial face of infrapharyngobranchial 2, the posterior one inserting on infrapharyngobranchial 3.

OBLIQUUS DORSALIS HI (Figure 82: OBL.D.).—There

are two sections of this muscle. The anterior one

connects the anterodorsal face of epibranchial 3 to

the anterior and lateral faces of infrapharyngobranchial 3. The posterior part passes from the dorsal face of epibranchial 3 to the dorsomedial face

of infrapharyngobranchial 3.

OBLIQUUS POSTERIOR (Figure 82: OBL.P.).—The

muscle connects the dorsomedial face of ceratobranchial 5 with the posterolateral face of epibranchial 4.

TRANSVERSI DORSALES II-III (Figure 82: TR.D.).—

The anterior muscle originates from the ventrolateral parasphenoid, with some posterior fibers

from a raphe in the dorsal midline. The fibers

insert on the dorsal face of epibranchial 2. The

posterior muscle arises from the dorsal midline and

inserts primarily on epibranchial 3, with some

fibers to epibranchial 4.

RETRACTOR DORSALIS (Figure 82: D.RETR.).—A

well-developed muscle, arising from the lateral and

ventral faces of the basioccipital and inserting on

the dorsomedial region of infrapharyngobranchial

3.

ADDUCTORES IV-V (Figure 82: AD.).—The muscle

of the fourth arch spans the medial side of the

articulation between the epibranchial and ceratobranchial. Adductor V connects the anterodorsal

tip of ceratobranchial 5 and the posterodorsal face

of epibranchial 4.

SPHINCTER OESOPHAGI (Figures 81, 82: s.o.).—The

muscle encircles the esophagus, attaching mainly

to the posterior margins of the fifth ceratobranchials, and lying above transversus ventralis V.

Dorsally it attaches to epibranchial 4, with a few

fibers passing to infrapharyngobranchial 3. There
22 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

is a small bundle of fibers crossing the dorsal midline above the retractor dorsalis.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 78: ABD.S.).—

Origin is from the posterolateral face of the

cleithrum, the fibers passing posterodorsally to

insert on the dorsal bases of the principal fin rays.

ABDUCTOR PROFUNDUS (Figures 78, 80: ABD.P.).—

The fibers originate almost exclusively from the

anterolateral face of the coracoid, a few fibers

coming from the posterolateral cleithrum. The

muscle inserts on the ventrolateral bases of the

principal fin rays and on the lateral base of the

lateral half of the vestigial ray.

ARRECTOR VENTRALIS (Figures 78, 80: ARR.V.).—

The muscle originates from the posterolateral face

of the cleithrum and inserts on the lateral face of

the medial half of the vestigial fin ray.

ADDUCTOR SUPERFICIALIS (Figure 83: ADD.S.).—

Origin is from the anteroventral face of the postcleithrum and the posteromedial face of the dorsal

region of the cleithrum. The fibers insert on the

dorsomedial faces of the principal rays distal to

their bases, the more medial fibers serving the more

ventral rays.

ADDUCTOR PROFUNDUS (Figure 83: ADD.P.).—The

muscle passes from the posterior cleithrum and

medial coracoid to insert on the ventromedial

flanges of the bases of the principal fin rays.

ARRECTOR DORSALIS (Figure 83: ARR.D.). — The

fibers originate from the medial cleithrum between

the two adductor sections, and insert on the medial

base of the vestigial fin ray.

CORACORADIALIS (Figure 83: COR.R).—The muscle originates largely from the fascia overlying the

medial surface of the adductor profundus. It attaches to the medial process of the ventral radial.

PROTRACTOR PECTORALIS (Figure 80: P.P.).—The

fibers fan out from their origin on the ventral tip

of the pterotic and insert on the anterodorsal face

of the cleithrum. The more anteromedial fibers

spread out to cover the posteromedial wall of the

branchial chamber.

LEVATOR PECTORALIS (Figure 80: TR.).—Origin is

from the posteroventral tip of the pterotic, the

muscle passing posteriorly to insert on the anterodorsal tip of the cleithrum.

MUSCLES OF THE PELVIC GIRDLE

ARRECTOR VENTRALIS PELVICUS? (Figure 84:

A.V.P.).—The muscle originates in the ventral groove

in the pelvis. Just before inserting, the fibers divide

into left and right tendons. These continue posteriorly, dorsal to the first and second encasing

scales to attach to the ventrolateral faces of the

fin ray element.

ADDUCTOR SUPERFICIALIS PELVICUS? (Figure 84:

A.S.P. ).—This bilateral muscle originates in the

dorsal groove of the pelvis. Posteriorly, the tendons

pass through a tunnel in the dorsal lobe of the

pelvis and insert on either side of the dorsal half

of the fin ray element.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORS ALES (Figure 78: INC.).—There

are no inclinators to the spiny dorsal fin. Each ray

in the soft dorsal fin receives an inclinator, which

inserts on the lateral base of the ray just above

the insertion of the erector and depressor muscles.

The fibers originate in the fascia overlying the

epaxialis.

ERECTORES DORSALES (Figures 78, 80: EREC).—

The first erector is very powerful and passes from

the dorsal faces of the frontal and supraoccipital

to the anterolateral base of the first dorsal spine.

The second erector arises from the posterior epiotic

and, passing medial to the strut supporting the

first spine, inserts on the lateral base of the second

spine. There is no erector to the third spine. The

erectors of the soft dorsal fin originate from the

lateral faces of the posterior halves of the pterygiophores (just behind the lateral flanges) and the

neural spines. The fibers reach the centra, and insert on the anterolateral bases of the fin rays.

DEPRESSORES DORSALES (Figures 78, 80: DEPR.).—

The depressors of the first two spines arise from

the epiotic. The first passes medial to the lateral

strut of the pterygiophore before turning dorsally

to insert on the posterolateral base of the spine,

while the second muscle passes lateral to the strut

to insert on the anterior face of the elongate,

posteroventrally directed base of the second spine,

ventral to its articulation with the lateral strut.

The depressor of the third spine originates from

the anteroventral face of the first pterygiophore

of the soft dorsal fin. It passes anterodorsomedially,
NUMBER 155 23

through a foramen in the pterygiophore, to insert

on the base of the third spine. The depressors of

the soft dorsal fin originate from the anterolateral

faces of the pterygiophores and the neural spines,

and insert on the posterolateral bases of the rays.

SUPRACARINALIS ANTERIOR (Figure 78: S.ANT.).—

The muscle connects the posterodorsolateral face

of the frontal to the anterolateral edge of the first

basal pterygiophore of the spiny dorsal fin.

SUPRACARINALIS MEDIUS (Figure 80: S.MED.).—

The muscle attaches to the posterolateral face of

the second pterygiophore and fans out to insert

broadly on the anterior face of the first pterygiophore of the soft dorsal fin.

SUPRACARINALIS POSTERIOR (Figure 85; s. POST.).—

Fibers arise from the posterodorsolateral face of

the last pterygiophore of the soft dorsal fin and

the tip of the neural spine of the eighth caudal

vertebra. The fibers attach to the tips of the ninth

and tenth neural spines.

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES (Figure 78: INC.).—Each

fin ray possesses an inclinator arising from the

fascia overlying the hypaxial body musculature

and inserting on the lateral base of the ray. There

is a large residual inclinator, which inserts on the

base of the first anal pterygiophore. The indinators

decrease in size posteriorly.

ERECTORES ANALES.—Each fin ray has an erector

muscle, which originates from the lateral faces of

the pterygiophore and the haemal spines, and inserts on the anterolateral base of the ray.

DEPRESSORES ANALES.—The depressor muscles

originate on the lateral faces of the pterygiophores

and haemal spines, and insert on the posterolateral

bases of each fin ray.

INFRACARINALIS ANTERIOR (Figures 78, 80: INF.

A.).—The muscle is well developed. It arises from the

posteroventral region of the cleithrum and inserts

broadly over the lateral face of the pelvic bone.

Posteriorly, it passes into a lateral tunnel in the

bone, to whose walls fibers attach.

INFRACARINALIS MEDIUS (Figures 78, 80: INF.M.).—

The fibers arise from the posterolateral face of the

pelvic bone and pass posterodorsally to join with

the fibers of the obliquus inferioris before acquiring attachment to the first anal pterygiophore.

The muscle overlaps the posterior fibers of the

infracarinalis anterior anterolaterally.

INFRACARINALIS POSTERIOR (Figure 85: INF.P.).—

Fibers arise from the posteroventrolateral tip of the

last anal pterygiophore and pass posteriorly, attaching to the tips of the haemal spines of the

eighth and ninth vertebrae before ending on the

midregion of the anterior face of the haemal spine

of the tenth caudal vertebra.

MUSCLES OF THE CAUDAL FIN

INTERRADIAUS (Figure 85a: INT.).—The muscle

consists of a number of bundles of fibers passing

between the rays and meeting at the midlateral

line. Fibers usually pass over two or three rays

before reattaching.

HYPOCHORDAL LONGITUDINALIS (Figure 85a:

H.L.).—Origin is from the lateral faces of hypural

2 and the urostyle, the fibers coursing posterodorsally to insert on the lateral bases of the fin rays

D 2-4.

FLEXOR DORSALIS (Figure 856: F.D.).—The muscle

originates from the dorsolateral faces of the tenth

caudal vertebral centrum and the urostyle. Fibers

insert on the anterolateral bases of the rays D 1-6.

FLEXOR DORSALIS SUPERIOR (Figure 85: F.D.S.).—A

well-developed muscle, originating from the dorsolateral faces of the neural spines and centra of the

eighth and ninth caudal vertebrae, and inserting on

the anterodorsolateral base of fin ray D 6.

FLEXOR VENTRALIS (Figure 856: F.V.).—Origin is

from the ventrolateral face of the hypural plate,

the ural, and the penultimate centrum. The fibers

insert on the anterolateral bases of rays V 1-6.

FLEXOR VENTRALIS INFERIOR (Figure 85: F.V.I.).—

A well-developed muscle, arising from the ventrolateral faces of the haemal spines and vertebral

centra of the eighth and ninth caudal vertebrae,

with a few fibers from the tenth haemal spine. The

muscle inserts on the anteroventrolateral base of

ray V 6.

TRANSVERSUS CAUDALIS (Figure 85&: TR.C).—

Fibers originate from the dorsolateral face of the

hypural plate beneath the urostyle and pass posteroventrally to insert on the anterodorsal base of ray

V 1.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 78, 85a: EPAX.).—Anteriorly
24 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

the fibers arise from the supracleithrum, posttemporal, pterotic, epiotic, and exoccipital. The muscle

is fairly uniform as it passes posteriorly, the myocommata becoming more horizontally oriented.

The fibers grade into a fascia which inserts on the

lateral bases of rays D 1-6.

OBLIQUUS SUPERIORIS (Figures 78, 85a: OBL.S.).—

Anteriorly the fibers lie beneath the anteroventral

downgrowth of the fibers of the epaxialis. The

section does not reach the pectoral girdle anteriorly, and these fibers are also overlain by the

anterodorsal region of the obliquus inferioris. They

become exposed posteriorly, where they grade into

a fascia with the obliquus inferioris to attach to

the lateral bases of rays V 2-6. Dorsomedially, the

fibers are attached to the centra of the vertebrae.

OBLIQUUS INFERIORIS (Figure 78: OBL.I.).—The

anteroventral section of the muscle arises from the

posterior face of the coracoid, the lateral fibers

being continuous with the sternohyoideus. Most of

the fibers from this region attach to the anteroventral face of the postcleithrum. Above the postcleithrum, the fibers arise from the fascia overlying the

region of the epipleurals and course anteroventrally to attach to the posterodorsal face of the postcleithrum. The more posterior fibers become

increasingly horizontal, and the section apparently

fuses with the obliquus superioris to insert compoundly on rays V 2-6.

SPINALIS (Figure 80: SPIN.).—Fibers arise from

the posterodorsal face of the epiotic and pass

posteriorly to attach to the tips of the neural spines

of the second and third abdominal vertebrae.

CUTANEOUS MUSCLES

TRANSVERSUS CUTANEOUS (Figure 78: TR.CUT.).—

The fibers of this muscle arise from the fascia

overlying the anteroventral portion of the obliquus

inferioris and pass ventromedially to attach to the

ventrolateral face of the pelvis. The posterodorsal

fibers attach to the anteroventral tip of the postcleithrum. The section probably arose from the

infracarinalis medius as postulated by Rosen (1913:

3), although he did not distinguish the infracarinalis medius from the obliquus inferioris.

Balistapus undulatus (Mungo Park)

FIGURES 86, 87a

A 2o is not as well developed anterodorsally,

thus exposing more of A la in lateral view. Ramus

mandibularis V passes through A 2 a dorsal to the

division between the two upper A 2 sections. A 2 Y

is better developed, and is bipinnate.

There is a hiatus between the extreme posterior

fibers of the protractor hyoidei and the fibers

anterior to them, and the hyohyoideus inferioris

is visible externally through the gap.

The medial section of the sternohyoideus has

separated completely from the main mass of the

muscle. There is, in addition, another section which

has separated off from the main mass. It passes

horizontally from the cleithrum (lateral to the

sternobranchialis) to insert on the urohyal just

lateral to the insertion of the vertical section. A

myocomma is present across the middle of the

length of this horizontal section. Rectus ventralis I

has completely separated from obliquus ventralis I.

The first levator externus is better developed

and the fifth less well developed than in B. vetuln.

Transversus dorsalis II originates only from the

lateral parasphenoid, with no fibers from a middorsal raphe. The arrector ventralis pelvicus is as

for B. vetula, except that the tendons join again

before inserting on the fin ray element. The transversus caudalis is not as well developed as in B.

vetula.

Melichthys niger (Bloch)

FIGURE 88

A 23 is more exposed posterodorsally, and A 2Y

is more obviously bipinnate. The hyomandibular

crest is somewhat larger, with the result that there

is more of the levator arcus palatini visible lateraliy.

The cutaneous portion of the protractor hyoidei

is much better developed and overlies a greater

part of the ventral branchiostegal rays, while the

inner and more ventral sections are reduced. There

is some development of the horizontal section of the

sternohyoideus described in B. undulatus. The

posterodorsomedial fibers of the sternobranchialis

do not meet their antimeres. The pharyngoclavicularis internus has partially divided into two portions. Levator externus V is less well developed

than in either of the two previous species, and

transversus dorsalis II is as for B. vetula. The arrector ventralis pelvicus and transversus caudalis are

as for B. undulatus.
NUMBER 155 25

Rhinecanthvs aculeatus (Linnaeus)

FIGURE 89

The levator arcus palatini is poorly developed,

with only a few fibers to the anterodorsal face of

the hyomandibular, while the levator operculi is

well developed, extending inward beneath the dilatator operculi to the ventral process of the

pterotic.

The cutaneous portion of the protractor hyoidei

is well developed, and there is a fifth section of

the hyohyoidei abductors. The sternohyoideus is

as was described for B. undulatus.

The fifth levator externus is well developed, and

partially fused to the fourth levator anterodorsally.

Transversus dorsalis II arises only from the parasphenoid.

The posterior region of the groove in the pelvis

which contains the arrector ventralis pelvicus has

closed over ventrally to form a tube. The tendon

remains single throughout its length, but divides

immediately before its insertion.

Odonus niger (Ruppell)

FIGURE 90

The adductor mandibulae is somewhat reduced

in size, particularly sections A 2<* and A 2P. A 3

is also reduced, but A la and A IP are better

developed than in the other balistids examined.

The cutaneous portion of the protractor hyoidei

is well developed, with some fibers of the more

dorsal portions originating from the dorsal three

branchiostegal rays. The sections of the hyohyoidei

abductores from the second to fifth rays are much

reduced. The horizontal and vertical subdivisions

of the sternohyoideus are present, and the pharyngoclavicularis externus is poorly developed.

Only the ventral fibers of levator externus V are

developed, and these grade into an aponeurotic

sheet dorsally, which fuses to the outer face of the

midregion of levator IV. Both levatores interni are

poorly developed, and transversus dorsalis II is as for

B. vetula. The protractor pectoralis is well developed. The arrector ventralis pelvicus is as for R.

aculeatus, the movable portion of the pelvis being

much reduced. The inclinator analis of the first

anal fin ray appears to consist of two sections, and

the transversus caudalis is small.

Summary of Balistidae

In the balistids, there is some variation in the

relative development of the sections of the adductor mandibulae, and minor differences in the size

of the levator arcus palatini. The development of

the cutaneous portion of the protractor hyoidei

differs, as does the relative size of the sections of

the hyohyoidei abductores. Two subdivisions of

the sternohyoideus are usually present (one vertical and the other horizontal). The extent to which

levator externus V develops varies, and transversus

dorsalis II may or may not have fibers arising from

the midline behind its main origin on the parasphenoid. There is some variation in the posterior

region of the arrector ventralis pelvicus, and the

transversus caudalis is usually poorly developed.

While there is more variation in the Balistidae than in either of the two preceding families, it is usually of a minor nature and relatively

unimportant at the level of analysis to be used

here.

Myological Descriptions of Representative Monacanthids

The general body outline of representatives of

this family is given in Figure 4. Out of the 22

genera recognized by Fraser-Bunner (1941a), species

representing 10 genera have been examined. Body

form is basically conservative, and similar to balistids, although there are numerous exceptions such

as the long snouted Oxymonacanthus and the tremendously elongate Anacanthus. The scales are

spinose. The dorsal spines, of which there are

normally two (the second being able to lock the

first in position), vary in position from behind the

eye to the anterior snout region. The pelvis may

be in evidence externally, as in balistids, or may

simply be a movable strut of bone completely

covered by skin. Locomotion is mainly by undulations of the soft dorsal and anal fins, turning being

achieved by the pectoral fins and flexion of the

body. The caudal fin does not seem to be used at
26

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

all in Pseudalutarius (Wickler, 1962), although it

may be brought into play in escape movements.

The teeth are much the same as in the balistids,

but the general body plan is less robust.

The food of monacanthids is rather varied. Some

species are totally herbivorous, others omnivorous,

while yet others ingest primarily animal matter.

They are usually found around coral reefs and on

the sea-grass flats of tropical waters, although some

species do occur in colder regions.

Pervagor tnelanocephalus (Sleeker)

FIGURES 87b, 91-99

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 876, 91, 92; see

also Figure 101 of Stephanolepis auratus: A la,

A IP, A 1Y, A 2a, A 23, A 3).—The A 1 section

of the adductor mandibulae has become considerably modified. A la and A la' arise from the lateral

face of the ethmoid (and the ventral surface of the

lateral flange) as well as from the prefrontal and

the infraorbital ligament (between the prefrontal

and hyomandibular). A la' (Figure 91) grades into

an aponeurotic sheet which fades into the tissues of

the upper lip. It is a fairly distinct subsection,

although there is some intermingling of fibers posteriorly. The main mass of A 1 is formed by A la,

which inserts on the posteroventrolateral face of

the maxilla by a broad aponeurosis. Medial to this

are two other sections, arising from the infraorbital

ligament. The dorsal of these, A h (see Figure

101) soon grades into a flat aponeurosis which

attaches to the lateral process of the ethmoid supporting the palatine, and the palatine itself. Its

function is obscure. Beneath this muscle is A IP'

(Figure 101), a smallish, somewhat flattened muscle

which develops a tendon anteriorly joining that of

A la laterally and that of A 13 medially. A IP

originates from the lateral faces of the mesopterygoid and metapterygoid and inserts on the medial

face of the maxilla. A 2 consists of two subdivisions.

A 2a originates from the prefrontal, infraorbital

ligament, and the hyomandibular. A 23 is well

developed and is separated from A 2a by ramus

mandibularis V. It arises from the anterior hyomandibular, the preopercle, symplectic, quadrate,

and posterior metapterygoid. Some of the anteroventral fibers originate from the extreme ventral

flange of the preopercle, but do not form a distinct

section as in the balistids. A 2a and A 23 insert by

a common tendon on the medial face of the dentary. A 3 is completely separate from A 2 except for

the shared tendinous insertion on the dentary. It

originates from the lateral faces of the metapterygoid and quadrate.

LEVATOR ARCUS PALATINI.—The muscle is poorly

developed, and no longer visible in superficial

lateral view. It originates from the ventromedial

face of the orbital process of the sphenotic and the

anterolateral prootic. The fibers fan out to insert

on the posterodorsal and posterolateral faces of the

hyomandibular, the two regions being separated by

a thin ridge.

DILATATOR OPERCULI (Figure 91: D.O.).—Origin

is from the ventrolateral face of the orbital process

of the sphenotic and the pterotic, the fibers inserting on the anterolateral face and dorsal rim of the

opercle.

LEVATOR OPERCULI (Figure 91: L.O.).—The muscle

originates from the anterodorsal supracleithrum

and anterolateral posttemporal and inserts on the

posterodorsal ridge of the opercle.

ADDUCTOR ARCUS PALATINI (Figure 92: A.A.P.).—

Fibers arise from the ventrolateral faces of the

vomer and parasphenoid and insert on the dorsomedial hyomandibular and metapterygoid and

dorsal mesopterygoid. The anterior region of the

pterygoids underlies the parasphenoid, with which

it is in contact dorsally. The muscle is not developed in the posterior half of the floor of the orbit.

RETRACTOR ARCUS PALATINI (Figures 91, 92: R.A.

P.).—The muscle has completely separated from the

adductor arcus palatini, and the division of the

fibers into anterior and posterior sections as in

balistids is not nearly as striking (the ventral

aponeurosis of the anterior portion being absent).

A small anterolateral bundle arises from the lateral

process of the ethmoid. Fibers from this region

insert mainly on the cartilagenous plug between

the ectopterygoid, maxilla, and vomer, the rest of

the muscle inserting predominantly on the ectopterygoid. Origin is entirely from the lateral and

ventral surfaces of the dorsal flange of the ethmoid.

ADDUCTOR OPERCULI (Figure 95: AD.OP. ).—This is

a well-developed muscle originating from the lateral prootic and pterotic, and passing lateroventrally

in front of the ventral process of the pterotic. It
NUMBER 155 27

inserts on the dorsomedial margin of the opercle

posterior to that bone's articulation with the

hyomandibular.

MUSCLES OF THE HYOID REGION

INTERMANDIBULARIS.—The muscle crosses transversely between the halves of the lower jaw just

behind the symphysis. It lies completely dorsal to

the protractor hyoidei.

PROTRACTOR HYOIDEI (Figures 91, 92: PR.HY.).—

The fibers arise from the posteroventrolateral face

of the anterohyal. The dorsal fibers pass anteriorly

to the ventromedial face of the dentary. The more

ventral fibers originate at an increasingly transverse

angle and meet their antimeres in the midventral

line. There is an obvious myocomma which passes

anteriorly as it proceeds toward the midline in the

dorsal region.

HYOHYOIDEUS INFERIORIS (Figures 91, 95: HY.

IN.).—Origin is from the entire ventral surface of

the anterohyal, the fibers passing ventrally to a

midventral raphe and attachment on the ventrolateral face of the urohyal.

HYOHYOIDEI ABDUCTORES (Figure 91: H.AB.).—

Only the three ventral rays possess these muscles.

The more dorsal two are small, passing from the

medial faces of the rays to the fascia on the medial

face of the anterohyal. The ventralmost muscle is

broad and flat, arising anteriorly in the region of

the urohyal and ventrohyal and inserting along the

dorsomedial border of the first ray.

HYOHYOIDEI ADDUCTORES (Figures 91, 92: H.AD.).—

The fibers arise from the fascia overlying the dorsal surface of the sternohyoideus, and pass posterodorsally, medial to the branchiostegal rays and the

preopercle, to fade out in the tissue beneath the

opercle and subopercle.

STERNOHYOIDEUS (Figures 91, 95: STH.).—The

fibers arise mainly from the posterior myocomma

separating the muscle from the obliquus inferioris,

with only a few medial fibers from the anteroventral cleithrum. There are two myocommata, the

fibers inserting anterodorsally by a tendon to the

posteroventral face of the ventrohyal and anteroventrally on the posterolateral face of the urohyal.

Ventromedially, a small bundle of fibers arises from

the anteroventral tip of the cleithrum and inserts

on the posteroventral tip of the urohyal. It is very

similar to the vertical bundle found in the same

position in balistids, and is probably a homologous

structure.

STERNOBRANCHIALIS (Figures 94, 95: STB.).—Origin is from the anteroventromedial cleithrum. The

fibers pass vertically upward, meeting briefly with

their antimeres. The tendon divides into two sections, the anterior of which inserts broadly on the

posterodorsal urohyal while the posterior part inserts on the ventral face of hypobranchial 3.

RETRACTOR INTEROPERCULI (Figure 93: R.I.).—

Origin is from the medial face of the posteroventral

flange of the preopercle. The fibers converge to

insert on the anterior part of the interopercleopercle ligament. Just in front of this, the interopercle attaches to the posterohyal and the medial

preopercle. The muscle is probably a derivative of

the hyohyoidei adductores.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 94, 95:

PHC.E.).—The fibers arise from the anterior face of

the cleithrum, and diverge as they pass dorsally. The

anterior section inserts on the extreme anterolateral

tip of ceratobranchial 5, while the tendon of the

posterior part joins the dorsal tendon of the coracobranchialis internus to insert on the anteroventral

face of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 94, 95:

PHC.I.).—The muscle originates from the anteromedial face of the dorsal cleithrum, and passes

anteriorly. It grades into a tendon which divides

into a dorsal section to ceratobranchial 5 (joining

the posterior tendon of the pharyngoclavicularis

externus) and a main anterior tendon which inserts

on the anteroventromedial faces of the fourth ceratobranchials.

OBLIQUI VENTRALES I, HI (Figure 94: OBL.V.).—

Both muscles are small, spanning the joints between the hypobranchials and ceratobranchials of

their respective arches. Obliquus II has apparently

been modified into a section of rectus II.

TRANSVERSI VENTRALES III-V (Figure 94: TR.V.).—

The anteriormost of this series connects the ventral

faces of the third ceratobranchials, and is single.

In the cases of transversi IV and V, certain changes

have occurred. Both these muscles consist of two

bundles of fibers, crossing each other in the midline

at some 30 degrees. The anterior muscles both connect the anteromedial faces of the fourth cerato-
28 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

branchials across the midline, the posterior muscles

connecting the fifth ceratobranchials in a like manner. In both pairs, the fibers passing from anterior

left to posterior right lie ventral to those passing

in the opposite direction.

RECTI VENTRALES I, ii, iv (Figures 94, 95: RECT.

v.).—Rectus I connects the ventrolateral surface of

basibranchial 1 (with some fibers to the posterodorsal face of the dorsohyal) to the anterolateral

face of ceratobranchial 1. The main mass of rectus

II lies between the anteroventral face of ceratobranchial 2 and the dorsolateral face of the urohyal.

A very small lateral section attaches to the posteroventromedial face of ceratobranchial 1. The major

section of rectus IV passes between the ventromedial face of hypobranchial 3 and the anterolateral tip of ceratobranchial 4. The posteroventral

section found in triacanthoids and balistids is

presumably represented by a slip of fibers diverging from the posterior face of transversus ventralis

III, and attaching to the dorsal surface of the tendon

of the rectus communis.

RECTUS COMMUNIS (Figures 94, 95: R.COMM.).—

The muscle originates from the posterodorsal urohyal and grades into a tendon which inserts on the

anterolateral face of ceratobranchial 5. As described

above, the tendon receives a small bundle of fibers

from the posterior face of the transversus ventralis

III.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI i-rv (Figure 95: L.EXT. ).—The

four muscles originate from the anteroventral face

of the prootic, the origins becoming more lateral

posteriorly. Levator HI inserts on epibranchials 3

and 4, the other three levators inserting on the

epibranchials of their respective arches. The third

levator is partially fused to the fourth, and a small

aponeurosis connects the latter muscle to the dorsal

tip of ceratobranchial 5.

LEVATORES INTERNI II-III (Figure 96: L.INT.).—

Origin is from the prootic posterior to the hyomandibular foramen. Levator II passes anteroventrally

to insert on the medial face of infrapharyngobranchial 2, while levator III inserts on the dorsolateral

face of infrapharyngobranchial 3.

OBLIQUUS DORSALIS HI (Figure 96: OBL.D.).—There

are two sections, the anterior of which passes

between the anterodorsal face of infrapharyngobranchial 2 and the anterodorsal face of epibranchial 3, lying beneath transversus dorsalis II. The

smaller, posterior portion connects the third infrapharyngobranchial to epibranchial 3.

OBLIQUUS POSTERIOR (Figure 96: OBL.P. ).—A

small muscle, which passes from the anterodorsal

tip of ceratobranchial 5 to the posterodorsal face

of epibranchial 4.

TRANSVERSI DORSALES II-III (Figure 96: TR.D.).—

The anterior muscle originates from the lateral

parasphenoid and passes out laterally to insert on

the posterodorsal face of epibranchial 2. Transversus III crosses the dorsal midline between the

dorsal faces of the third epibranchials, with a few

of the more anterior fibers arising from the parasphenoid.

RETRACTOR DORSALIS (Figure 96: D.RETR.).—Origin is from the posterodorsolateral surface of the

basioccipital, the fibers coursing anteroventrally to

insert on the dorsomedial face of the infrapharyngobranchial 3.

ADDUCTORES IV-V (Figure 96: AD.).—Adductor IV

passes across the angle between the medial faces

of the fourth epibranchial and ceratobranchial.

Adductor V connects the anterodorsal face of ceratobranchial 5 to the posterodorsal face of ceratobranchial 4.

SPHINCTER OESOPHAGI (Figures 94, 95, 96: s.o.).—;

The muscle encircles the esophagus, attaching to

ceratobranchial 5, epibranchial 4, and infrapharyngobranchial 3. A fairly large section passes anterodorsal to the retractor dorsalis.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 91: ABD.S.).—

Origin is from the ventrolateral and posteroventral

cleithrum. The fibers insert on the anterolateral

bases of each of the principal fin rays.

ABDUCTOR PROFUNDUS (Figure 95: ABD.P.).—The

fibers arise from the anterolateral face of the coracoid and insert on the bases of the principal fin

rays in the region of the posteroventral flange.

ARRECTOR VENTRALIS (Figure 91: ARR.V.).—The

muscle originates from the lateral cleithrum behind the ala laminaris and above the abductor

superficialis. The fibers insert on the lateral base

of the vestigial fin ray, of which only the medial

half remains.

ADDUCTOR SUPERFICIALIS (Figure 97: ADD.S.).—
NUMBER 155 29

Origin is from the dorsomedial face of the cleithrum, the fibers inserting on the dorsomedial faces

of the principal rays, a little distal to their bases.

The more dorsal fibers serve the more ventral rays,

and lie more medially.

ADDUCTOR PROFUNDUS (Figure 97: ADD.P. ).—The

fibers arise from the medial faces of the cleithrum

and coracoid, and insert on the posteroventromedial flanges of the principal fin rays.

ARRECTOR DORSALIS (Figure 97: ARR.D. ).—The

muscle originates from the medial face of the

cleithrum and passes posterodorsally to insert on

the posteromedial flange of the vestigial fin ray.

CORACORADIALIS (Figure 97: COR.R.).—This small

muscle arises from the anterior face of the medial

flange of the coracoid. It passes laterally to insert

on the medial face of the ventral (fourth) radial.

PROTRACTOR PECTORALIS (Figure 95: P.P.).—The

muscle connects the posteroventral tip of the

pterotic to the anterodorsal face of the cleithrum.

LEVATOR PECTORALIS (Figure 95: TR.).—A somewhat smaller muscle, arising from the ventral process of the pterotic and inserting on the extreme

anterodorsal tip of the cleithrum.

MUSCLES OF THE PELVIC GIRDLE

ARRECTOR VENTRALIS PELVICUS (Figure 98: A.V.

P.)—The fibers arise from the midventral groove in

the pelvis, the structure becoming somewhat bipinnate posteriorly. A tendon develops (and may

be split into left and right components), which

inserts on the anteroventral tip of the cartilagenous

plug. There did not appear to be a ventral fin ray

element, but the specimens were not alizarin

stained.

ADDUCTOR SUPERFICIALIS PELVICUS (Figure 98:

A.S.P. ).—The muscle consists of left and right

halves, and originates in the trough on the posterodorsal face of the pelvis in front of the dorsal lobe.

The tendons pass posteriorly through a bony canal

and insert on the fin ray element, the right tendon

also attaching partly to the cartilagenous plug.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORSALES (Figure 91: INC.).—These

muscles serve the soft dorsal fin only. They arise

in the fascia between the lateral processes of the

distal ends of the pterygiophores and insert on the

lateral bases of the fin rays, decreasing in size

posteriorly.

ERECTORES DORSALES (Figures 91, 92: EREC).—The

erector to the first spine is large, and originates

from the anterolateral face of the pterygiophore,

the frontal, and the supraoccipital. It inserts on

the anterolateral base of the spine. The erector to

the reduced second spine arises from the frontal

and inserts on the lateral surface of the main body

of the spine. The erectors to the fin rays originate

from the posterolateral halves of the pterygiophores

and the anterolateral faces of the neural spines.

They insert on the anterolateral bases of the rays.

DEPRESSORES DORSALES (Figure 91: DEPR.).—The

first depressor passes from the frontal to the posterolateral base of the spine, while that to the second

spine arises from the frontal and lateral face of the

pterygiophore and inserts on the distal tip of the

ventrolateral process. The muscles to the fin rays

originate from the anterolateral halves of the

pterygiophores and posterolateral faces of the

neural spines and insert on the posterolateral bases

of the rays.

SUPRACARINALIS MEDIUS (Figure 91: S.MED.).—

The muscle passes from the posterior tip of the

first basal pterygiophore to attach in a long, vertical groove in the anterior face of the first pterygiophore of the soft dorsal fin. Some of the more

medial fibers attach to the tips of the neural spines

of the second and third vertebrae.

SUPRACARINALIS POSTERIOR (Figure 99: S.POST.).—

The muscle connects the posterodorsal face of the

last pterygiophore of the dorsal fin with the anterodorsal tip of the last neural spine. The medial part

of the muscle attaches to the dorsolateral tips of

the neural spines of the antipenultimate and penultimate vertebrae.

MUSCLES OF THE ANAL FIN

INCLINATORES AN ALES (Figure 91: INC.).—The

enlarged, residual first inclinator passes from the

fascia overlying the obliquus inferioris to attach to

the anteroventral face of the first anal pterygiophore. All the other inclinators, one of which inserts on the lateral base of each ray, arise in the

fascia between the lateral pterygiophore processes

and the hypaxial body muscles.

ERECTORES ANALES.—The erectors originate from

the posterior halves of the pterygiophores and in-
30

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

sert tendinously on the anterolateral base of each

fin ray.

DEPRESSORES ANALES.—The fibers arise from the

anterolateral halves of the pterygiophores and insert on the posterolateral bases of the fin rays.

INFRACARINALIS ANTERIOR (Figures 91, 95: INF.

A. ).—The muscle originates from the ventromedial

coracoid and posteroventral cleithrum. Insertion

is in the large ventrolateral groove in the pelvis,

the fibers almost reaching the posterior margin of

the bone.

INFRACARINALIS MEDIUS (Figure 91: INF.M.).—This

is a thin, sheetlike muscle extending posteriorly

from the lateral face of the pelvis. It joins the

ventral fibers of the obliquus inferioris, the more

dorsal fibers reaching the posteroventral tip of the

postcleithrum, while the posteroventral fibers attach to the ventrolateral face of the first anal

pterygiophore.

INFRACARINALIS POSTERIOR (Figure 99: INF.P.).—

Fibers arise from the posteroventral tip of the last

anal pterygiophore. They attach to the tips of the

next two haemal spines before ending on the anteroventral tip of the last haemal spine.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 99a: INT.).—The muscle is

made up of slips which pass from the lateral faces

of the rays toward the midline. They usually attach

to the bases of the rays lying nearer the midline,

but cross over each other in the case of the fibers

from rays V 1 and D 1.

HYPOCHORDAL LONGITUDINALIS (Figure 99a: H.L.).—

The fibers arise from the ventrolateral face of the

hypural plate and divide into three tendons, which

insert on the ventrolateral bases of rays D 1-3.

FLEXOR DORSALIS (Figure 996: F.D.).—Origin is

from the dorsolateral faces of the 18th and 19th

centra, the neural spine of the former, the urostyle,

and the epurals. The fibers divide into six tendons,

inserting on the bases of rays D 1-6.

FLEXOR DORSALIS SUPERIOR (Figure 99: F.D.S.).

Origin is from the dorsolateral faces of the third

and fourth last vertebrae and their neural spines,

the fibers inserting on the base of ray D 6.

FLEXOR VENTRALIS (Figure 99b: F.V.).—The fibers

arise from the ventrolateral faces of the antipenultimate and penultimate centra, the haemal spine of

the former and the hypural plate. The muscle inserts on the bases of rays V 1-6.

FLEXOR VENTRALIS INFERIOR (Figure 99: F.V.L).—

The muscle originates from the ventrolateral faces

of the centra of the third and fourth last vertebrae

and their haemal spines and inserts on the base

of ray V 6.

TRANSVERSUS CAUDALIS (Figure 996: TR.C).—Origin is from the dorsolateral face of the hypural

plate. The fibers pass posteroventrally to insert on

the dorsal base of ray V 1.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 91, 95, 99a: EPAX.).—The

fibers attach anteriorly to the epiotic, exoccipital,

and supraoccipital. Posteriorly, the angle of the

myocommata increases to a sharp V, whose apex

lies posteriorly. Only the section closest to the midline contributes fibers to the insertion tendons

serving rays D 1-5. The dorsal portion fades into

a fascia covering the whole region, joining with a

similar fascia from the obliquus inferioris. A small

slip of the ventral section attaches to epural 2.

OBLIQUUS SUPERIORIS (Figures 91, 99a: OBL.S.).—

The anterior region does not reach the skull, arising from the lateral surface of the vertebral column.

The size of the muscle increases posteriorly, the

last myomere inserting on the bases of rays D 1 and

V 1-5, with a small ventral slip to the posterolateral face of the first hypural.

OBLIQUUS INFERIORIS (Figures 91,95, 99a: OBL.L).—

The anteroventral portion of the muscle arises from

the fascia overlying the lateral coracoid-cleithrum

region, and is anteriorly continuous with the sternohyoideus. Some fibers arise from the posterolateral

face of the coracoid. Most of the fibers from this

region attach to the anteroventral face of the postclei thrum. A number of myomeres arise from the

lateral midline, the fibers passing anteroventrally to

insert aponeurotically on the posterodorsal face of

the postcleithrum. Fiber direction gradually becomes horizontal posteriorly, and the muscle grades

into a vague aponeurosis which joins that from the

dorsal portion of the epaxialis to cover the caudal

peduncular region.

SPINALIS.—The muscle originates from the posterior face of the epiotic and the first dorsal pterygiophore and inserts on the dorsolateral tips of the

neural spines of the second and third vertebrae.
NUMBER 155 31

CUTANEOUS MUSCLES

TRANSVERSUS CUTANEOUS (Figure 91: TR.CUT.).—

This is a small muscle arising from the middle of

the anteroventral face of the postcleithrum and

passing downward to insert on the ventrolateral

face of the pelvis.

Stephanolepis auratus (Castlenau)

FIGURES 100-101

A 23 is slightly more bulky, and the levator

arcus palatini is just visible in lateral view. The

ventral portion of rectus ventralis IV is smaller,

and the arch-shaped ligament between the ventral

processes of the third hypobranchials is lost. The

coracoradialis is less well developed, and the medial

projection for its insertion on the fourth radial is

not as prominent. The adductor superficialis pelvicus is single anteriorly but bilaterally symmetrical

posteriorly. The depressor of the second spine is

larger, and is partially overlain by the epaxialis

which attaches to the lateral surface of the pterygiophore between the two spines. The anterodorsal

portion of the obliquus inferioris above the postcleithrum inserts musculously on that bone. The

spinalis is small and inserts only on the neural spine

of the second vertebra.

Paramonacanthus barnardi Fraser-Brunner

FIGURE 102

The adductor mandibulae and levator arcus

palatini are as for S. auratus, and the dilatator

operculi is more parallel fibered. The retractor

interoperculi is better developed. The adductor superficialis pelvicus is single, as is the arrector ventralis pelvicus. The erector dorsalis to the first spine

is contained in a fairly deep depression and is partially overlain dorsally by a lateral flange of the

pterygiophore. The anterodorsal portion of the

obliquus inferioris is as for S. auratus.

Chaetoderma spinosissimus (Quoy and Gaimard)

FIGURE 103

A la' is rather poorly developed, and A 1Y is

visible laterally between A la and A IP'. A 3 is

well developed, and visible anterior to A 23. The

levator operculi originates more from the pterotic

and posttemporal than from the supracleithrum.

Rectus ventralis II has developed extra fibers on

its medial surface which join their antimeres in the

midline. The fibers are separated from the more

anterior section by the anterior tendon of the sternobranchialis to hypobranchial 2 (see Figure 111 of

Aluterus for the extreme of this condition). The

ventral portion of rectus ventralis IV is well developed. In both the transversi ventrales, the relative positioning of the sections crossing over each

other is reversed; i.e., the anterior left section lies

dorsal to the section arising from the anterior

right. The muscle fibers of the arrector ventralis

pelvicus and the adductor superficialis pelvicus are

virtually absent, but fairly well-developed tendons

remain. The residual inclinator of the anal fin is

aponeurotic, with no muscle fibers visible. The

spinalis is poorly developed, and the transversus

cutaneous does not reach the postcleithrum dorsally.

Paraluteres prionurus (Sleeker)

FIGURE 104

A la is fairly small, originating primarily from

the ethmoid with only a few fibers from the prefrontal. A la' is well developed, while A h has

enlarged to take over much of the site of origin

of A la. It now originates from the prefrontal and

the entire anterodorsal half of the infraorbital

ligament. The insertion has also expanded to include the dorsolateral face of the maxilla as well

as the ethmoid and palatine. A 13 is larger and

visible in superficial lateral view, while A 13' is

small. Another section, A 13", has separated from

its dorsomedial face and inserts on the maxilla near

A la. Both the A 13 sections mentioned originate

from the anterior hyomandibular, A 13' also receiving a few fibers from the infraorbital ligament.

A 2a is much reduced, but A 23 and A 3 are more

normal. The adductor arcus palatini is tremendously well developed, and inserts primarily on the entire dorsomedial half of the metapterygoid.

All the fibers of the hyohyoideus inferioris attach

to the ventrolateral face of the urohyal, and the

dorsal fibers of the hyohyoidei adductores attach to

the dorsomedial face of the opercle. The ventro-
32

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

medial section of the sternohyoideus is poorly

developed, and the insertion of the sternobranchialis is confined to the ventral faces of hypobranchials 2 and 3.

The small lateral section of rectus ventralis II

attaches more to hypobranchial 1 than to ceratobranchial 1, and the medial section is as for C.

spinosissimus. The ventral portion of rectus ventralis IV is absent, and transversus ventralis IV

consists only of a single transverse fiber bundle.

The arrector ventralis pelvicus and adductor superficialis pelvicus are absent, as they are in all the

remaining species except Cantherhines pardalis.

The infracarinalis anterior is small, and the infracarinalis posterior and supracarinalis posterior

do not attach to the tips of the haemal and neural

spines respectively, apart from the spine on which

they insert. The last three vertebrae possess welldeveloped lateral flanges, and the origins of the

flexor dorsalis and flexor ventralis have shifted partially onto these surfaces. The spinalis is well

developed, and originates mainly from the exoccipital.

Cantherhines pardalis (Riippell)

FIGURE 105

A la' is poorly developed, while A 2? has expanded its origin dorsally to reach the prefrontal.

A IP' inserts by a broad, aponeurotic sheet over

the posterolateral face of the maxilla ventral to the

palatine. A IP is well developed, while A 1Y has

a somewhat restricted insertion on the ethmoid

and palatine. A 3 is partially fused to A 2P anteroventrally. There are no fibers of A 2P from the

ventrolateral flange of the preopercle.

All six branchiostegal rays may receive a slip

of the hyohyoidei adductores, but that to the dorsalmost ray may be absent. The halves of the sternobranchialis do not meet in the midline. The

pharyngoclavicularis externus is bifid, rectus ventralis II is as for C. spinosissimus, and the ventral

portion of rectus ventralis IV is well developed.

The abductor profundus is considerably exposed

ventrally beneath the abductor superficialis. Both

the adductor profundus and the protractor pectoralis are well developed. The arrector ventralis

pelvicus appears to be represented by a tendon

which just reaches the posteroventral surface of the

pelvis from the canal in which it lies. The adductor

superficialis pelvicus is present as a tiny paired

muscle on the dorsal surface of the pelvis. It passes

through the canal in the dorsal lobe, and both tendons insert on the posterior face of the cartilagenous

plug. Some of the more ventral fibers of the infracarinalis medius attach to the thickened dermis

around the anus.

The anterodorsal portion of the obliquus inferioris is made up mainly of an aponeurotic sheet, the

muscle fibers being confined to a narrow band in

the middle of the sheet.

Oxymonacanthus longirostris

(Bloch and Schneider)

FIGURE 106

A la is rather small, passing from the ventral

face of the maxilla to its origin at the anterior

junction of the frontal and prefrontal. Above A la',

a third subdivision, A la", is recognizable. It originates along the ventrolateral surface of the ethmoid

ridge and passes into the connective tissue of the

lips dorsal to A la'. A IP' has acquired some origin

from the prefrontal, and partially overlies A lv

ventrally. A 1Y itself is well developed with a

broad insertion. A 2a is also well developed, its

origin stretching from the prefrontal to the hyomandibular and including the infraorbital ligament. At about the middle of its origin is a gap

in the fibers, through which passes a sensory branch

of nerve V. There are no fibers of A 2P from the

ventrolateral flange of the preopercle (and this is

true for all the remaining species). A 3 is poorly

developed. The ridge of bone on the posterodorsal

surface of the hyomandibular is well developed,

the fibers of the levator arcus palatini inserting

on either side of it. The lateral wall of the fossa

containing the origin of this muscle has broken

down, and the muscle is visible laterally between

the frontal and sphenotic. A few fibers of the

levator operculi arise from the pterotic. The adductor arcus palatini is visible in lateral view,

and stretches to the rear of the orbit. The retractor

arcus palatini is poorly developed, with no fibers to

the palatine.

There is no ventromedial section to the sternohyoideus, and the aponeuroses of the sternobranchialis are more consolidated. The retractor

interoperculi is absent.
NUMBER 155 S3

The pharyngoclavicularis externus is single, and

inserts on ceratobranchial 5, while the pharyngoclavicularis internus has been reduced to a straplike, parallel fibered muscle. Obliquus ventralis I is

well developed, being almost the same size as rectus

ventralis I. The medial portion of rectus ventralis

II is as described for C. spinosissimus, and the

ventral portion of rectus ventralis IV is absent (as

in P. prionurus).

The depressor dorsales of the first spine has

broken through beneath the lateral strut of the

pterygiophore supporting the base of the spine, and

has extended its origin into the fossa originally

occupied only by the erector dorsalis to the first

spine. Erector dorsalis II passes posteromedially to

its insertion, while depressor dorsalis II courses

posterolaterally to the base of the second spine.

Both penetrate the tunnel beneath the flange, but

do not extend beyond its anterior margin. The

hypochordal longitudinalis inserts only on rays D 2

and 3, and the transversus caudalis is poorly developed. The transversus cutaneous fans out from

the posterodorsal face of the pelvis, and attaches to

the coracoid anteriorly.

Pseudalutarius nasicornis (Schlegel)

FIGURE 107

The adductor mandibulae complex is very much

like that of O. longirostris, although the snout is

not as elongated. A la' inserts more on the maxilla

than the lips, and A IP' completely overlies A 1Y.

Where O. longirostris differs from P. melanocephalus, the descriptions also apply to P. nasicornis,

with the following exceptions.

There is a larger section of the levator operculi

originating from the pterotic, and the retractor

interoperculi is present. Obliquus ventralis II is

apparently absent.

The general positioning of the dorsal branchial

levators seems more primitive than in P. melanocephalus, since all the origins are from the posterolateral face of the prootic, and none from the poorly

developed prootic shelf. The small size of the shelf

could, of course, be secondary.

Aluterus monoceros (Linnaeus)

FIGURES 108-113

A la (Figure 108) is a single section, the more

dorsal part of the insertion extending into the

tissues of the lips. The origin has expanded enormously to include not only the anteroventral prefrontal, but the entire infraorbital ligament as well.

A 13' is long and thin (Figure 109), while A 13

and A 1Y are more like the generalized condition.

A 2a (Figure 108) is much reduced dorsally, there

being no fibers from the infraorbital ligament. A

3 is small. The adductor arcus palatini (Figure 110:

A.A.P.) is divided into two sections by the junction

between the metapterygoid and the parasphenoid.

The retractor arcus palatini is not subdivided at

all.

Most of the posteroventral fibers of the protractor

hyoidei arise from the fascia over the anteroventral

tip of the cleithrum. These fibers are almost at right

angles to the ones originating from the posteroventral face of the anterohyal.

Rectus ventralis II (Figure 111: RECT.V.) is well

developed. There is a lateral section to hypobranchial 1, an anterior section to the dorsolateral urohyal, and a transverse section across the midline.

The anterior tendon of the sternobranchialis inserts on hypobranchial 2 between the two latter

sections. The arrangements of the two bundles of

fibers forming transversus ventralis IV are as for

P. melanocephalus, but the relative positions of the

bundles is reversed in transversus V. The pharyngoclavicularis externus is bifid, with tendons to

ceratobranchials 4 and 5.

The anterior extension of the prootic shelf has

carried the origins of the levatores externi with it

(Figure 112: L.EXT.). There is some variation in the

mode of insertion in levators II and IV. They may

insert by a continuous aponeurosis on epibranchials

3 and 4, or separately. If the latter is the case,

the anterior tendon may send a small branch to

epibranchial 4. The aponeurosis of levator II sends

a small section to epibranchial 3. The levatores

interni retain their origin from the prootic beneath

the hyomandibular foramen. Some fibers of transversus dorsalis III overlap onto the dorsal face of

epibranchial 4. Obliquus dorsalis III is somewhat

modified. Fibers from infrapharyngobranchial 2

pass to three different points of attachment. The

medial fibers pass posteriorly to the dorsal face

of infrapharyngobranchial 3. The more lateral

fibers attach to epibranchial 3 (as in P. melanocephalus), while some of the ventromedial fibers

loop around epibranchial 2 and reattach to infra-
34

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

pharyngobranchial 2.

The adductor superficial is well developed (Figure 113: ADD.S.). The supracarinalis medius is

present as a pair of cylindrical muscles, rather than

the more usual triangular muscle. The erectores

and depressores dorsales do not reach the vertebral

column ventrally. The infracarinalis medius forms

a broad tendon posterodorsally before grading into

the fascia beneath the postcleithrum. Both the

transversus caudalis and the spinalis are small, the

latter muscle arising from the posterodorsal face of

the first vertebra. In view of the fact that A. monoceros exhibits certain characters not found in any

of the other monacanthids examined (particularly

in the form of the adductor mandibulae complex),

two additional species of the genus were dissected.

Aluterus heudeloti Hollard

The only difference noted was that there were

tough connective tissue strands from the posterodorsolateral face of A 2a to the prefrontal.

Aluterus schoepfi (Walbaum)

The findings were the same as for A. heudeloti.

In the smaller specimen (57 mm SL), A 2a has

relatively larger dorsal extent than in any other

Aluterus examined, the posterodorsal fibers almost

reaching the infraorbital ligament.

Anacanthus barbatus Gray

FIGURE 114

Various modifications are apparent in the adductor mandibulae complex. A la' originates from the

lateral and medial ethmoid. It is partially covered

by A la posteriorly, and has a long, thin aponeurosis which crosses the upper jaw to insert in the

anterior tissues of the barbel. A la arises from the

ethmoid behind A la' and from the prefrontal. It

also develops a long aponeurosis, which fades into

the tissues of the barbel at its posterior base. These

sections are only connected to the upper jaw by

connective tissue. A 13 is fairly well developed, and

has its normal relationships. A IP' is absent, and

A h is poorly developed, originating from the

prefrontal and the infraorbital ligament. The fibers

of the latter section soon become aponeurotic, and

insert on the ethmoid and parasphenoid posterior

to the retractor arcus palatini. A 2a and A 23 are

not separated posteriorly, but are so anteriorly,

where the ramus mandibularis V passes between

them. The orbital process of the sphenotic almost

reaches the hyomandibular. The levator operculi

and levator arcus palatini are very small, but the

dilatator operculi remains well developed. The adductor arcus palatini is confined to a region in

front of the orbit, but behind the retractor arcus

palatini. The latter muscle is very well developed.

Both the hyohyoidei abductores and the hyohyoidei adductores are well developed, the latter muscle attaching to three of the four branchiostegal

rays. The hyohyoideus inferioris meets its antimere

in the ventral midline, and is not attached to the

urohyal.

Rectus ventralis II is single, with the fibers passing anteromedially to the midline, where they join

to form two tendons to the urohyal. Obliquus ventralis III is absent, as is the ventral section of rectus

IV.

The dorsal ends of the gill arches lie beneath the

prootic shelf at the level of the prefrontal. Levatores externus IV inserts only on epibranchial 4.

The levatores interni arise from the prootic just

before the start of the shelf at the rear of the orbit.

They course the length of the orbit before inserting on the infrapharyngobranchials.

The levator pectoralis is very well developed,

originating from the elongated ventral process of

the pterotic and sphenotic, the medial fibers arising from the posteromedial face of the hyomandibular. It inserts on the supracleithrum and

anterodorsal cleithrum. The protractor pectoralis is

less well developed, but also more anterior in

position.

There is a single dorsal spine, the depressor dorsalis being larger than the erector dorsalis. The

supracarinalis medius is musculous at its attachment sites, but aponeurotic in the middle twothirds, where it attaches to the tips of the neural

spines. The infracarinalis anterior has partially

fused in the midline. The residual inclinator of

the anal fin is very well developed, grading into

the infracarinalis medius anteriorly and the obliquus inferioris dorsally. The interradialis is well

developed, but both the hypochordal longitudinalis

and the transversus caudalis are absent.
NUMBER 155 35

Summary of Monacanthidae

The monacanthids exhibit a wide range of variation and progressive specialization, which may

or may not be obviously related to the body form.

The adductor mandibulae is very variable in both

the number of subdivisions and in the relative development of these sections. The basic plan is,

however, fairly consistent, with two subdivisions

of A la and A IP, and a single section of unknown function, A 1Y. Section A 2 usually has two

subdivisions, separated by the path of ramus mandibularis V, the posterodorsal surface of A 2a sometimes reaching the prefrontal. The levator arcus

palatini may be well developed or almost absent,

or it may be visible laterally owing to a breakdown

in the lateral wall of the dilatator fossa. The adductor arcus palatini may be well or poorly developed, confined to the region in front of the orbit,

stretch half way across it, or it may reach the rear

of the orbit. The retractor arcus palatini is well

separated from the above muscle, and may be well

or poorly developed.

The protractor hyoidei may have a superficial

section arising from the fascia overlying the ventral

tips of the cleithra, and the hyohyoideus inferioris

may arise partially, totally, or not at all from the

ventrolateral face of the urohyal. There are minor

variations in the extent of development and number of the sections of the branchiostegal ray

musculature. The amount of separation and

consolidation of the ventromedial section of the

sternohyoideus varies, as does the insertion of the

sternobranchialis. The retractor interoperculi is

sometimes absent.

The pharyngoclavicularis externus is often bifid,

and rectus II shows progressive specialization and

subdivision. The ventral fiber bundle of rectus ventralis IV may be absent, and the relative positioning and development of the sections of transversus

ventralis IV differs.

The position of origin of the levatores externi

depends on the location of the prootic shelf, while

that of the levatores interni seems independent of

this variable. The muscles serving the fin ray elements of the pelvis are variously developed or absent, the ray elements themselves being absent in

certain genera. Muscles attaching to the dorsal

spines vary in sites of origin and relative development. The anterodorsal portion of the obliquus

inferioris may be musculous or largely aponeurotic,

and the sites of origin of the spinalis vary.

At least some of the variation in monacanthids

is attributable to the large number of species and

genera and the great variety of body form. They

would appear to have undergone "explosive" evolution, and form the apomorph sister group of the

balistids.

Myological Descriptions of Representative Aracanids

The general body form of these fishes is illustrated in Figure 5. In his review of the genera of

ostracioid fishes, Fraser-Brunner (1935) recognized

six genera in what was originally a subfamily, but

which he later raised to familial rank (1941b).

Representatives of two of these six genera have

been dissected for the present study. The fishes

are encased in a bony cuirass of modified scales

from the snout to the level of the posterior margin

of the dorsal and anal fins. Neither this family,

nor the succeeding one (Ostraciidae) show any evidence of pelvic fins or girdle. They are presumably

slow swimmers, but virtually nothing is known about

their life habits. They appear to live in deepish

water (down to 100 fathoms). The gut contents

of the specimens dissected for this study indicate

a diet of small crustacea and worms.

The aracanids are usually considered, in effect,

as the plesiomorph sister group of the next family,

the Ostraciidae, and derived originally from a common ancestor with the balistids (although it has

also been suggested that they arose from a neotenic

molid ancestor).

Kentrocapros aculeatus (Houttuyn)

FIGURES 115, 116a, 117-124

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 115, 116, 117:

A 13, A 2a, A 23, A 3).—A 2a is well developed, originating from the dorsolateral parasphenoid, the interior face of the prootic shelf, and the

anterodorsal margin of the hyomandibular. Fibers
36

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

also arise from the tendinous sheath on the dorsomedial face of the muscle. The more medial fibers

in this region are not completely distinct from the

lateral fibers of A 13" (Figure 117) posteriorly.

A 23 arises from the preopercle and hyomandibular, the fibers passing anterodorsally. They tend

to pass more medially than do those of A 2a, but

join to form a common tendon before inserting

on the inner face of the dentary. Ramus mandibularis V emerges from beneath A IP" and passes

lateral to the other sections of A IP. It appears

superficially from beneath the anterior fibers of A

23. The sections of A 1 are not well separated

either from each other or from the overlying A 2.

A 13" is the dorsalmost section and originates

from the anterior face of the prootic shelf. Beneath

it, A IP' (Figure 117) arises from the dorsolateral

metapterygoid and anterior hyomandibular. It is

poorly separated from A IP, which arises from the

anterolateral face of the hyomandibular. The latter section partly overlies and intermingles with

A 3. Anteriorly, these four sections come together

to form a tendinous aponeurosis which divides into

a strong dorsal component to the medial face of

the maxilla and a weaker ventral one to the medial

face of the dentary.

LEVATOR ARCUS PALATINI (Figures 115: L.A.P.).—

This is a short, conical muscle originating from

the ventral face of the orbital process of the sphenotic and fanning out to insert on the anterolateral

face of the hyomandibular.

DILATATOR OPERCULI (Figure 115: D.O.).—The

fibers form a long, thin, bipinnate muscle which

arises from the dilatator fossa (mainly in the sphenotic) and inserts on the dorsal process of the

opercle.

LEVATOR OPERCULI (Figure 115: L.O.).—The muscle originates from the ventrolateral posttemporal

and inserts on the posterodorsal face of the opercle.

ADDUCTOR ARCUS PALATINI.—The muscle is short

and thick. It originates from the ventrolateral face

of the parasphenoid and inserts mainly on the

dorsomedial face of the metapterygoid. The anterior fibers pass outward to their insertion at an

increasingly anterolateral angle, and grade imperceptibly into the retractor arcus palatini. The muscle lies wholly in front of the orbit.

RETRACTOR ARCUS PALATINI (Figure 117: R.A.P.).

The muscle is fairly well developed, and, as stated,

not completely separate from the adductor arcus

palatini. The fibers arise from the anterodorsal

parasphenoid and pass anteroventrally to insert on

the posterodorsal face of the metapterygoid.

ADDUCTOR OPERCULI (Figures 119, 121: AD.OP. ).—

Fibers arise from the lateral face of the basioccipital

and anteroventral exoccipital, and insert on the

dorsomedial face of the opercle by a long tendon.

ADDUCTOR HYOMANDIBULAE (Figures 119, 121:

A.H.).—The muscle lies just above the adductor

operculi, and passes more anteriorly to insert on

the dorsomedial face of the hyomandibular. Its

origin is poorly separated from that of the adductor operculi, the muscle being derived from the

more posterodorsal fibers.

MUSCLES OF THE HYOID REGION

INTERMANDIBULARIS.—This is a small transverse

muscle spanning the symphysis between the dentaries, and being closely associated with the anterodorsal fibers of the protractor hyoidei.

PROTRACTOR HYOIDEI (Figures 115, 117, 118:

PR.HY.).—The muscle originates from the medial

face of the dentary near the symphysis and inserts

on the lateral faces of the anterohyal, posterohyal,

and the bases of the dorsal four branchiostegal rays.

The two halves remain separate for most of their

length, being joined by a midventral raphe just

below the jaws. A myocomma arises in the region

of the raphe, and passes posterodorsally. Some of

the more dorsal fibers attach to the interopercle.

HYOHYOIDEUS INFERIORIS (Figures 115, 118:

HY.IN.).—The muscle is rather small, and originates

from the posteroventral anterohyal and anteroventral posterohyal beneath the second branchiostegal

ray. The fibers pass down to the midline, where

they meet their antimeres in a midventral raphe.

HYOHYOIDEI ABDUCTORES (Figures 115, 118:

H.AB.).—These muscles insert on the medial faces

of the first four branchiostegal rays. The section to

the first ray arises from the ventromedial face of

the ventrohyal, that to the second ray originates

from the base of the first ray, while the slips to

the other rays arise from the base of the second ray

and the surrounding anterohyal.

HYOHYOIDEI ADDUCTORES (Figures 115, 117, 118:

H.AD.).—The muscle lies mainly in the lateral tissues of the opercular cavity. It attaches dorsally to

the sphenotic and prootic shelf. Ventrally, fibers

attach to the fascia covering the sternohyoideus
NUMBER 155 37

and the ventral surfaces of the branchial arches.

The more dorsal branchiostegal rays are partially

embedded in the fibers. A small slip of fibers arises

from the anteroventral region of the cleithrum and

courses dorsally to join the main mass in the vicinity of the opercular valve.

STERNOHYOIDEUS (Figures 115, 118, 119: STH.).—

The muscle consists of two sections. The main

lateral portion arises from the myocomma with

the obliquus inferioris lateral to the abductors of

the pectoral fin. It inserts on the posteroventral face

of the ventrohyal. A small, medial section of the

muscle originates from the anteroventral tip of the

cleithrum and inserts on the lateral face of the

small urohyal. It lies medial to the main body of

the muscle.

STERNOBRANCHIALIS (Figures 118, 119, 120: STB.).—

The fibers originate from the anteroventral

region of the cleithrum and pass dorsally to separate into two tendons. The anterior of these inserts

on hypobranchials 2 and 3 and ceratobranchial 3,

while the posterior tendon inserts on ceratobranchials 3 and 4.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 119,

120: PHC.E.).—This muscle is very well developed.

It originates from the anterior and ventromedial

surfaces of the cleithrum, dorsolateral to the origin

of the medial section of the sternohyoideus. The

fibers pass upward to insert on the ventral surface

of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 119,

120: PHC.I.).—The fibers arise from the anterodorsomedial face of the cleithrum and insert on the

ventral face of ceratobranchial 5.

OBLIQUUS VENTRALIS HI (Figures 119, 120: OBL.

v.).—The muscle is small, and connects the ventral

face of ceratobranchial 3 to the tip of the ventral

process of hypobranchial 3. The process is embedded

in a flat ligament which passes anteriorly to attach

to the posterior face of the urohyal.

TRANSVERSI VENTRALES IV-V (Figure 120: TR.V.).—

These two muscles connect the anteroventromedial

faces of the ceratobranchials of the fourth and fifth

arches across the ventral midline. The posterior

muscle is well developed.

RECTI VENTRALES I, ii, rv (Figures 119, 120:

RECT.V.).—The two anterior recti arise from the

ventral surfaces of the ceratobranchial-hypobranchial regions of the first and second arches respectively. Rectus I attaches to the posterodorsal face

of the dorsohyal, while rectus II passes anteromedially, fusing partly with its antimere and partly

with the ligament from the ventral process of hypobranchial 3. Rectus IV is well developed, and connects the ventral face of ceratobranchial 4 to the

arch-shaped ligament between the third hypobranchials. Some fibers intermingle with those of the

other side in the midline.

RECTUS COMMUNIS (Figures 119, 120: R.COMM.).—

The muscle arises from the posterior face of the

urohyal and inserts on the ventrolateral face of

ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I-IV (Figure 119: L.EXT.).—

The series is well developed. All the muscles originate from the ventral surface of the prootic shelf,

and insert on the dorsal faces of the respective

epibranchials. Levators III and IV are completely

fused dorsally, the bulk of the fibers affecting the

tendon serving the fourth epibranchial. The tendon

to epibranchial 3 arises from the anteromedial surface of this bundle.

LEVATORES INTERNI II, HI (Figures 115, 119, 121:

L.INT. ).—These are both enormously developed,

bipinnate muscles, which insert on infrapharyngobranchials 2-4. Levator II originates from the

posterolateral prootic, ventral pterotic, lateral exoccipital, and ventrolateral epiotic, and inserts on the

posterior face of infrapharyngobranchial 2. Levator

III overlies the posteroventral surface of the anterior muscle, and includes the pterotic, epiotic,

and exoccipital in its sites of origin. Anteriorly, the

muscle divides into two tendons, the anterior of

which inserts on infrapharyngobranchial 3, the posterior one attaching to the medial tip of epibranchial 4 and the tough connective tissue which

appears to contain the cartilagenous remains of infrapharyngobranchial 4. The posterolateral origin

of this muscle is visible in superficial lateral view.

OBLIQUUS DORSALIS HI (Figures 119, 121: OBL.D.).—

The muscle connects the dorsal face of epibranchial 3 to the dorsal face of infrapharyngobranchial

3, passing between the two tendons of levator internus III.

OBLIQUUS POSTERIOR (Figure 121: OBL.P.).—This
38

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

is a well-developed muscle, passing from the dorsomedial face of ceratobranchial 5 to the posterior

face of epibranchial 4.

TRANSVERSI DORSALES n, iv (Figure 121: TR.D.).—

Both muscles originate from middorsal raphes with

their antimeres. Transversus II passes out laterally

behind infrapharyngobranchial 2 to insert on the

dorsal face of epibranchial 2. The posterior muscle

inserts on the posterodorsal face of epibranchial 4.

RETRACTOR DORSALIS (Figures 119, 121: D.RETR.).—

Origin is from the lateral face of the basioccipital, the muscle passing anteriorly beneath Baudelot's ligament and the medial process of the

supracleithrum to insert in the connective tissue

surrounding the cartilagenous remains of infrapharyngobranchial 4 near the medial tip of epibranchial 4.

ADDUCTOR IV.—This is a poorly developed muscle, crossing the angle between the medial faces of

the fourth epibranchial and ceratobranchial. It is

embedded in thick connective tissue.

SPHINCTER OESOPHAGI (Figures 119, 120, 121:

s.o.).—The muscle surrounds the esophagus, attaching to the posterior faces of ceratobranchial 5

and epibranchial 4. A pair of ligaments arise from

the ventral surface and pass posterolaterally to

attach to the medial faces of the cleithra.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figures 115, 118: ABD.

s.).—Origin is from the lateral and posterior faces of

the cleithrum and the fascia overlying the abductor

profundus. The fibers insert on the anterolateral

bases of the principal fin rays.

ABDUCTOR PROFUNDUS (Figures 115, 118, 119:

ABD.P.).—A well-developed muscle, arising mainly

from the broad, lateral surface of the coracoid. The

tendons insert on the posteroventral bases of the

principal fin rays. There is a section to the lateral

base of the vestigial ray that arises from the medial

surface of the muscle mass serving the dorsalmost

ray.

ARRECTOR VENTRALIS (Figure 115: ARR.V.).—The

muscle originates from the anterolateral face of the

cleithrum and inserts on the anterolateral margin

of the medial half of the vestigial fin ray.

ADDUCTOR SUPERFICIAL^ (Figure 123: ADD.S.).—

Origin is from the posterodorsomedial face of the

cleithrum. The muscle inserts on the anteromedial

faces of the principal rays distal to their bases. The

more ventral fibers pass more dorsolaterally to serve

the more dorsal rays.

ADDUCTOR PROFUNDUS (Figures 115, 118, 123:

ADD.P. ).—A well-developed muscle originating from

the medial coracoid and posteromedial cleithrum.

It inserts on the posteroventromedial flanges of the

principal fin rays.

ARRECTOR DORSALIS (Figure 123: ARR.D. ).—The

muscle originates from the medial face of the cleithrum, lying lateral to the adductor profundus and

medial to the adductor superficialis. It inserts on

the ventromedial base of the vestigial fin ray.

CORACORADIALIS (Figure 123: COR.R.).—A small

muscle, consisting of only a few fibers from the

posterodorsal face of the coracoid to the posteroventral face of the fourth radial.

MUSCLES OF THE DORSAL FIN

ERECTORES DORSALES (Figure 122: EREC).—These

are greatly expanded muscles, whose origin covers

the centra and neural spines of the fourth to

twelfth vertebrae as well as the pterygiophores of

the dorsal fin. Each erector is partially overlain

posterolaterally by the depressor muscle of the same

fin ray. The muscles decrease in size posteriorly,

and insert tendinously on the anterolateral bases

of the fin rays.

DEPRESSORES DORSALES (Figure 122: DEPR.).—

These muscles share their sites of origin with the

erectors, but are somewhat more laterally situated.

They insert tendinously on the posterolateral bases

of the fin rays, and decrease in size posteriorly.

SUPRACARINALIS ANTERIOR (Figures 115, 122:

S.ANT.).—Origin is from the posterodorsal face of

the supraoccipital and the lateral face of its spine.

The fibers pass posteriorly to insert on the tips of

the neural spines of the third and fourth vertebrae

and the anterior face of the "supraneural" (= basal

pterygiophore of the now absent spiny dorsal fin).

SUPRACARINALIS POSTERIOR (Figures 122, 1246:

S.POST.).—The muscle arises from the posterodorsal

face of the neural spine of the thirteenth vertebra

and courses posteriorly, attaching to the neural

spines of the succeeding vertebrae, to end on the

neural spine of the penultimate vertebra.
NUMBER 155 39

MUSCLES OF THE ANAL FIN

ERECTORES AN ALES (Figure 122: EREC).—The first

three muscles arise from the anterior face of the

laterally displaced pterygiophores, the other muscles originating from the posterior and lateral faces

of the pterygiophores. Insertion is tendinous on

the anterolateral bases of the fin rays, the muscles

decreasing in size posteriorly.

DEPRESSORES ANALES (Figure 122: DEPR.).—The

muscles lie immediately behind the erectors of the

respective fin rays, and have the same origins. They

insert on the posterolateral bases of the rays, decreasing in size caudally.

INFRACARINALIS POSTERIOR (Figures 122, 124&:

INF.P. ).—The muscle arises from the posteroventral

tip of the last anal pterygiophore. It passes posteriorly to attach to the anteroventral margin of the

haemal spine of the penultimate vertebra.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 124a: INT.).—The muscle

courses dorsoventrally across the fin rays, a slip of

the more posterior fibers attaching to the ventrolateral (rays D 1—5) or dorsolateral (rays V 1-6)

faces of the rays.

HYPOCHORDAL LONGITUDINALIS (Figure 124a:

H.L.).—The muscle originates from the lateral face

of the ventral part of the hypural plate. It inserts

beneath the interradialis on the ventrolateral bases

of rays D 3—5.

FLEXOR DORSALIS (Figure 1246: F.D.).—The fibers

arise from the dorsolateral faces of the centra and

neural spines of the last three vertebrae, and insert

on the bases of rays D 1-4. It is poorly separated

from the epaxialis laterally and the flexor dorsalis

superior dorsally.

FLEXOR DORSALIS SUPERIOR (Figure 124: F.D.S.).—

Origin is from the dorsolateral surface of the penultimate vertebra, the muscle inserting on the

anterolateral base of ray D 5.

FLEXOR VENTRALIS (Figure 1246: F.V.).—The muscle originates from the centrum and haemal spine

of the penultimate vertebra and the anteroventral

border of the hypural plate. It inserts on the anterolateral bases of rays V 1-5.

FLEXOR VENTRALIS INFERIOR (Figure 124: F.V.I.).—

The fibers arise from the lateral tip of the haemal

spine of the penultimate vertebra and insert on the

anterolateral base of ray V 6.

TRANSVERSUS CAUDALIS (Figure 1246: TR.C).—The

muscle is well developed, and originates from the

entire dorsolateral surface of the hypural plate,

reaching as far anteriorly as the ural centrum. It

inserts by three distinct tendons (the ventral one

of which serves two rays) on the dorsolateral bases

of rays V 2-5.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 115, 122, 124a: EPAX.).—The

two portions of the muscle are well separated anteriorly, but grade into each other posteriorly. The

dorsal moiety attaches anteriorly to the posterior

faces of the supraoccipital and exoccipital. The

ventral section is larger, and arises anteriorly from

the lateral faces of the anterior vertebrae. It increases in size posteriorly, where it overlaps both

centra and parts of the haemal arches. The muscle

inserts on the lateral bases of the dorsal caudal

fin rays, and is poorly separated from the flexor

dorsalis medially.

OBLIQUUS SUPERIORIS (Figures 122, 124a: OBL.S.).—

The muscle is poorly developed, particularly anteriorly, where it arises from the ventrolateral face

of the epaxialis. Posteriorly, the lateral septum

fades out, and it is not clear how much the obliquus

superioris contributes to the musculature inserting

on the ventral caudal fin rays.

OBLIQUUS INFERIORIS (Figures 115, 118, 122:

OBL.L).—The anteroventral section of the muscle

passes from the posterolateral face of the coracoid

to the anteroventral face of the postcleithrum. It

is partially overlain by the sternohyoideus anterolaterally. The anterodorsal section is much reduced.

It originates from the ventrolateral ridge of the

epiotic (where it shows faint traces of segmentation) and inserts on the dorsal face of the postcleithra. Posteriorly it grades into an aponeurotic

fascia overlying the greatly expanded lobes of the

liver, which cover the obliquus superioris and

epaxialis in this region. Posteroventrally, the muscle is small, and soon grades into an aponeurotic

sheet which overlies and intermingles with the

obliquus superioris.

Capropygia unistriata Kaup

FIGURE 125

A 2 is poorly subdivided, with no clear-cut sep-
40 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

aration of parts. It is, however, bipinnate, and

could easily have arisen or given rise to the condition in K. aculeatus. There is no intermingling of

fibers with the underlying A 13. A 13" is better

separated from the more ventral portions of A 1,

and originates exclusively from the prootic shelf.

The ventral fibers do not intermingle with those

of A 3, although they do share the archlike tendon

between the maxilla and dentary. The levator and

dilatator operculi are smaller. The retractor arcus

palatini is continuous with the adductor arcus

palatini anteriorly and ventrally, and merely consists of a more anterior-posterior orientation of

these muscle fibers. There is no adductor hyomandibulae.

The sternobranchialis has completely separated

into two sections, and its origin just overlaps the

ventrolateral face of the cleithrum. Levator externus III is not fused to levator IV, but is closely

applied to it. Adductor IV is well developed. The

adductor superficialis has some fibers originating

from the ventral face of the medial process of the

cleithrum. The adductor profundus is better developed, and is partly visible posteroventrally behind the coracoid. The supracarinales anterior are

fused in the midline, although a septum is present.

A single, small inclinator dorsalis passes to the

ventrolateral face of the first pterygiophore.

A small inclinator analis arises from the fascia

over the obliquus inferioris behind the posteroventral surface of the postcleithrum and attaches

to the ventrolateral face of the first anal pterygiophore. Behind this, a thin tendon attaches to the

anteroventral base of the first fin ray, and passes

posterodorsally. The fibers sweep dorsally in a large

semicircle to fade into the fascia beneath the posterior half of the dorsal fin, overlying the epaxialis.

The muscle appears to represent an extreme modification of the inclinator of the first anal fin ray.

The bulk of the body musculature consists of the

more ventral moiety of the epaxialis. This is well

separated from the more dorsal portion, and originates anteriorly from the vertebral column and

the fascia over the erectores and depressores dorsales. Posteriorly it forms a tendinous sheath attaching to the bases of all the caudal fin rays

(although part of the fibers in the ventral region

may be derived from the obliquus superioris. Attachment to the two outermost fin rays is mainly

derived from the dorsal and ventral portions of

the body musculature, and is tendinous.

Myological Descriptions of Representative Ostraciids

The normal body outline of members of this

family is illustrated in Figure 6. Fraser-Brunner

(1935, 1941b) recognized seven genera of ostraciids,

which he divided (1941b) among two subfamilies.

Representatives of four of the seven genera were

dissected. These fishes are rather similar to the

aracanids, except that the carapace extends behind

the base of the anal fin, and, in all but one species,

the dorsal fin as well. They are slow swimmers, living on or near coral reefs and sea-grass meadows.

Their food is comprised mainly of soft-bodied marine invertebrates, although crabs and other harder

bodied organisms are also eaten. The dorsal and

anal fins are used for locomotion, being supplemented by the caudal fin in emergencies. Steering

is achieved by the pectoral and caudal fins.

As stated above, the ostraciids are considered

the more specialized (apomorph) sister group of

the aracanids.

Ostracion tuberculatus Linnaeus

FICURES 1166, 126-134

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 1166, 126, 127:

A 13, A 2a, A 23, A 3).—The section A 2 is

well developed, and superficial in position. It consists of a smallish dorsal section, A 2 a, which

originates mainly from the region where the ethmoid, parasphenoid, prefrontal, and prootic meet

each other. The main mass is formed by A 2P,

which arises from the anterior margin of the

prootic shelf, the hyomandibular, and the preopercle. The two subdivisions share a tendinous insertion in the Meckelian fossa on the medial face

of the dentary. A 1 consists of three poorly separated subdivisions or "heads." A 13" (Figure

127) is best developed and originates from the
NUMBER 155 41

anterior and ventral faces of the prootic shelf and

the lateral parasphenoid. A IP' (Figure 127)

arises primarily from the metapterygoid, with a

few fibers from the mesopterygoid. A 13 originates

from the hyomandibular, ventrolateral metapterygoid, and symplectic. These subdivisions join to

insert on the medial face of the maxilla. The tendon curves ventrally in the form of an arch to join

with that of A 3. A 3 itself is fairly well developed,

originating from the quadrate and symplectic and

inserting on the medial face of the dentary (ventral to the insertion of A 2).

LEVATOR ARCUS PALATINI (Figure 126: L.A.P.).—

The muscle originates from the ventral face of

the sphenotic and inserts on the posterodorsal face

of the hyomandibular.

DILATATOR OPERCULI (Figure 126: D.O.).—Origin

is from the dilatator fossa behind the orbit. The

fossa is bounded variously by the sphenotic, pterotic, prootic, and frontal. Insertion is along the

dorsal rim of the opercle behind its articulation

with the hyomandibular.

LEVATOR OPERCULI (Figure 126: L.O.).—The

fibers arise from the anteroventral posttemporal

and insert on the posterodorsal rim of the opercle.

ADDUCTOR ARCUS PALATINI (Figure 128: A.A.P.).—

The muscle covers a fairly small area in front of

the orbit, where it is well developed. Origin is

from the ventrolateral parasphenoid, stretching

from its suture with the vomer to the flange beneath the prootic shelf. Insertion is on the dorsomedial faces of the mesopterygoid, metapterygoid,

and anterior hyomandibular.

RETRACTOR ARCUS PALATINI (Figure 128: R.A.P.).—

Origin is from the lateral parasphenoid above

the adductor arcus palatini. Anteriorly, a tendon

attaches to the dorsomedial face of the mesopterygoid. The dorsomedial face of the tendon is joined

by a small bundle of fibers originating from the

lateral face of the vomer.

ADDUCTOR OPERCULI (Figure 129: AD.OP.).—The

muscle has a fairly extensive horizontal origin from

the lateral faces of the parasphenoid and basioccipital. The fibers converge to form a long, thin

tendon which inserts on the dorsomedial face of

the opercle.

ADDUCTOR HYOMANDIBULAE (Figure 129: A.H.).—

This is a broad, short muscle originating from the

anterodorsomedial face of the cleithrum, as well

as Baudelot's ligament and the posttemporal in

that region. It passes anterolaterally to insert on

the anterodorsomedial face of the hyomandibular.

MUSCLES OF THE HYOID REGION

INTERMANDIBULARIS.—This is a small, short muscle which spans the midline just behind the symphysis between the dentaries. It is closely associated

with the anterodorsal fibers of the protractor hyoidei.

PROTRACTOR HYOIDEI (Figure 126: PR.HY.).—The

muscle arises from the posteroventral corner of the

anterohyal and the bases of the dorsalmost four

branchiostegal rays. The more ventral fibers join

their antimeres in the midline, while the more

dorsal fibers sweep upward to insert on the posterior margin of the lower jaw. A myocomma is

present in the anterior region.

HYOHYOIDEUS INFERIORIS (Figure 126: HY.IN.).—

This is a small muscle passing across the ventral

midline between the posteroventral margins of the

anterohyals. It lies lateral to the hyohyoidei abductores, but medial to the branchiostegal rays.

HYOHYOIDEI ABDUCTORES (Figure 126: H.AB.).—

This is a series of four muscles inserting on the

medial faces of the ventral four branchiostegal rays.

The ventralmost originates tendinously from the

ventrohyal, the others arising from the base of the

second ray and the surrounding anterohyal. They

lie medial to the hyohyoideus inferioris.

HYOHYOIDEI ADDUCTORES (Figure 126: H.AD.).—

The muscle consists of a well-developed sheet of

fibers in the lateral wall of the opercular cavity,

stretching from the fascia overlying the sternohyoideus to the medial faces of the preopercle, subopercle, opercle, and on up to the prootic shelf.

The more dorsal branchiostegal rays are attached

to the sheet by connective tissue. There is a small

bundle of fibers—arising from the anteroventral

cleithrum—which passes dorsally to attach to the

main mass of the muscle in the region of the

opercular flap.

STERNOHYOIDEUS (Figures 126, 127: STH.).—The

muscle is subdivided into two distinct sections. The

larger, lateral portion arises from the posterolateral

face of the coracoid and the posterior continuity

with the obliquus inferioris (it has effectively incorporated the anterior myomere of the latter muscle). It inserts on the posteroventral face of the

ventrohyal. The medial section originates from the
42

anteroventromedial face of the cleithrum and inserts on the ventromedial face of the ventrohyal.

Some of the more medial fibers attach to the small

urohyal.

STERNOBRANCHIALIS (Figures 129, 130: STB.).—

There are two well-separated sections of this muscle. The larger and more ventral of these originates

from the fascia overlying the pectoral fin abductors

and the anteroventrolateral face of the cleithrum.

Insertion is on the ventromedial face of hypobranchial 2. The dorsomedial section arises almost

exclusively from the anteroventral face of the cleithrum and inserts on the ventral faces of hypobranchial 3 and ceratobranchial 4.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 129,

130: PHC.E.).—The muscle originates from the ventromedial face of the cleithrum and passes dorsally

to insert on the ventral part of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 129,

130: PHC.L).—The fibers arise from the medial

region of the cleithrum and insert on the ventromedial face of ceratobranchial 5.

OBLIQUUS VENTRALIS HI (Figures 129, 130: OBL.

v.).—The muscle connects the anteroventral region

of ceratobranchial 3 to the ventral process of hypobranchial 3 and the arch-shaped ligament behind

it. Posteriorly, the fibers mingle somewhat with

those of rectus IV.

TRANSVERSI VENTRALES rv, v (Figure 130: TR.

v.).—The anterior muscle passes across the midline

between the anteromedial faces of the fourth ceratobranchials. Transversus V is better developed, and

connects the fifth ceratobranchials across the ventral midline.

RECTI VENTRALES, I, ii, rv (Figures 129, 130:

RECT.VJ.—The first muscle connects the dorsohyal

to ceratobranchial 1. Rectus II passes from the

anteroventral face of ceratobranchial 2 to a midventral raphe, the anterior portion of which is

firmly attached to basibranchial 1. Rectus IV is a

small muscle arising from the anteroventral region

of ceratobranchial 4 and attaching to the posterior

face of the arch-shaped ligament between the ventral processes of the third hypobranchials.

RECTUS COMMUNIS (Figures 129, 130: R.COMM.).

The muscle originates from the posterior face

of the urohyal. The fibers grade into a tendon at

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

about the level of the third hypobranchial and

insert on the ventrolateral base of ceratobranchial

5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I-IV (Figure 129: L.EXT.).—

The four muscles arise from the ventrolateral face

of the anterior part of the prootic shelf. Levator

II is overlain anterolaterally by levator I, and by

levators III and IV posterolaterally. The muscles

insert on the dorsolateral faces of epibranchials

1-4. Levator II is the smallest, and is poorly separated from levator IV dorsally.

LEVATORES INTERNI II, HI (Figures 129, 131: L.

INT.).—Levator II is well developed and originates

from the ventral prootic and pterotic and the lateral

parasphenoid. It inserts on the posterodorsal surface of infrapharyngobranchial 2. Levator III is

smaller and more flattened, and arises just behind

levator II. It includes the exoccipital in its sites

of origin, and inserts on the posterodorsal face of

infrapharyngobranchial 3.

OBLIQUUS POSTERIOR (Figure 131: OBL.P.).—A

well-developed muscle, which passes from the dorsomedial face of ceratobranchial 5 to the posterior

margin of epibranchial 4.

TRANSVERSI DORS ALES I-IV (Figures 129, 131: TR.

D.).—These four muscles connect the dorsal surfaces

of the left and right epibranchials of arches 1—4

across the dorsal midline. Transversus I passes between the levatores interni, and also receives a few

fibers from infrapharyngobranchial 3. The third

and fourth muscles are not well separated.

RETRACTOR DORSALIS (Figures 129, 131, 133:

D.RETR. ).—This is a well-developed muscle originating from the lateral faces of the first few

vertebrae and inserting on the medial face of infrapharyngobranchial 3.

SPHINCTER OESOPHAGI (Figures 129, 130, 131:

s.o.).—The muscle encircles the esophagus attached

to the posterior margin of ceratobranchial 5. It lies

dorsal to transversus ventralis V and ventral to

the retractor dorsalis.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 126: ABD.S.).—

The mass of the muscle originates from the posterolateral face of the anterolateral flange of the
NUMBER 155 43

cleithrum. It inserts on the anterolateral bases of

the principal fin rays.

ABDUCTOR PROFUNDUS (Figures 126, 129: ABD.P.).—

Origin is from the ventrolateral regions of the

coracoid and cleithrum. The muscle inserts on the

ventrolateral bases of the principal fin rays, with

a small tendon to the ventrolateral base of the

vestigial fin ray.

ARRECTOR VENTRALIS (Figures 126: ARR.V).—This

is a well-developed muscle, originating from the

posterior face of the anterolateral flange of the

cleithrum and inserting on the anterior base of the

vestigial fin ray (of which only the medial half is

present, the lateral half having apparently fused

with it).

ADDUCTOR SUPERFICIALIS (Figure 132: ADD.S.).—

The fibers arise from the posterodorsomedial face

of the cleithrum and insert on the anteromedial

faces of the principal rays distal to their bases. The

more ventral fibers serve the more dorsal rays,

and lie more laterally.

ADDUCTOR PROFUNDUS (Figure 132: ADD.P.).—A

well-developed muscle, originating over most of the

posteromedial faces of the cleithrum and coracoid.

It inserts on the ventromedial bases of the principal

fin rays.

ARRECTOR DORSALIS (Figure 132: ARR.D.).—Origin is from the posteromedial cleithrum, the muscle inserting on the medial base of the vestigial fin

ray.

MUSCLES OF THE DORSAL FIN

ERECTORES DORSALES (Figure 133: EREC).—Each

fin ray has an erector muscle inserting on its

anterolateral base. The fibers originate from the

lateral faces of the neural spines and centra of the

seventh to thirteenth vertebrae and the lateral

pterygiophores. They tend to lie somewhat lateral

to the depressores dorsales, and decrease in size

posteriorly.

DEPRESSORES DORSALES (Figure 133: DEPR.).—The

origin of these muscles is similar to that of the

erectors, but somewhat more medially. They insert

on the posterolateral bases of the fin rays.

SUPRACARINALIS POSTERIOR (Figures 133, 134a:

S.POST.).—The muscle arises from the posterior and

lateral faces of the neural spines of the thirteenth

and fourteenth vertebrae and ends on the anterodorsal face of the eighteenth vertebra. It passes between the bifid neural spines of the intervening

vertebrae, and is partially attached to their tips.

MUSCLES OF THE ANAL FIN

ERECTORES ANALES (Figure 133: EREC.).—The

first four muscles arise from the anterior faces of

the laterally displaced pterygiophores, the rest of

the muscles originating from the lateral faces of

the succeeding peterygiophores and the ventrolateral vertebral column. They insert on the anterolateral bases of all the fin rays.

DEPRESSORES DORSALES (Figure 133: DEPR.).—

These muscles originate just behind the erector of

each ray, lying somewhat more medially. They

insert on the posterolateral bases of the rays.

INFRACARINALIS POSTERIOR (Figure 133: INF.P.)—

The fibers arise from the posterior and lateral

faces of the haemal spine of the fourteenth vertebra and pass posteriorly to attach to the anteroventral surface of the haemal spine of the eighteenth

vertebra.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 134a: INT.).—The muscle

spans the caudal fin rays dorsoventrally, a short

distance from their bases. Each ray gives rise to a

small bundle of fibers joining the main mass posteriorly, and the more medial rays receive a small

fiber bundle anterolaterally.

HYPOCHORDAL LONGITUDINALIS (Figure 134:

H.L.).—The muscle originates on the ventrolateral

surface of the hypural plate, and inserts tendinously on the ventrolateral bases of rays D 3-5.

FLEXOR DORSALIS SUPERIOR (Figure 134: F.D.S.).—

This is a fairly small muscle, originating from the

dorsolateral region of the ural centrum and fused

hypural-epural region and inserting on the anterodorsal face of ray D 5.

FLEXOR VENTRALIS INFERIOR (Figure 134: F.V.I.).—

Origin is from the ventrolateral region of the ural

centrum and fused hypural-parhypural region, the

muscle inserting on the ventrolateral base of ray

V5.

TRANSVERSUS CAUDALIS (Figure 1346: TR.C).—The

fibers originate from the dorsolateral surface of the

hypural plate and insert tendinously on the dorsolateral faces of rays V 2-4.
44

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

LATERAL BODY MUSCLES

EPAXIALIS (Figures 126, 133, 134a: EPAX.J.—The

muscle arises anteriorly from the posterodorsal region of the skull. It passes posteriorly, and is only

attached to the vertebral column behind the dorsal

fin. Here the dorsolateral fibers grade into a tendon that joins a similar tendon from the obliquus

inferioris. The cruciform tendon thus formed inserts on the anterolateral bases of the uppermost

and lowermost rays of the caudal fin. The remaining fibers of the muscle more or less fuse with

the obliquus superioris medially, and insert by a

continuous tendinous sheath on the anterolateral

bases of the dorsal fin rays (D 1-5).

OBLIQUUS SUPERIORIS (Figures 133, 134a: OBL.S).—

The section is much reduced. Anteriorly it arises

from the lateral faces of the centra above the swim

bladder. Posteriorly, in the urostyle region, the

fibers appear to fuse dorsally with the epaxialis. It

inserts tendinously on the anterolateral bases of

the fin rays. In front of the anal fin the muscle

is completely separate from the epaxialis dorsally

and the obliquus inferioris ventrally.

OBLIQUUS INFERIORIS (Figures 126, 133, 134a:

OBL.1.).—The muscle consists of a ventral portion

only. Anteriorly, it is laterally continuous with

the sternohyoideus, the deeper fibers attaching to

the posterior face of the coracoid. Posteriorly, it

grades into a tendon that forms the ventral component of the cruciform tendon. Most of the fibers

from this tendon pass dorsally to the base of the

uppermost fin ray. There is little fusion with the

obliquus superioris, and the more ventrolateral

fibers have some connection to the carapace.

SWIM BLADDER MUSCLES

SWIM BLADDER "a" (Figure 133: s.BL.a.).—The

main mass of the muscle passes across the dorsal

surface of the anterior half of the swim bladder.

The fibers originate from the lateral faces of the

centra and overlying fascia of the middle abdominal vertebrae and pass posterolaterally to insert on the dorsolateral face of the swim bladder.

SWIM BLADDER "b".—The muscle lies beneath

swim bladder "a," near the midline. The fibers

lie in a longitudinal plane, inclining slightly toward the midline anteriorly. They lie very close

to the ventral surface of the seventh abdominal

vertebra, and the muscle as a whole is considerably

smaller than swim bladder "a."

The wall of the swim bladder beneath these

muscles is very thin, and the bladder is firmly attached to the ventral processes of the first six vertebrae (as described by Tyler, 1963b: 159).

Lactoria cornuta (Linnaeus)

FICURE 135

Certain proportional differences are evident. The

shorter snout and more down-tilted mouth are reflected in the shape of A 2 and the dilatator

operculi. The sections of A 2 are poorly separated,

as are those of A 10. This is even more apparent

in the 50 mm specimen, where both A 1 and A 2

appear as single, undivided muscles. The levator

arcus palatini is well developed, and its fibers are

not entirely separate from those of the dilatator

operculi posteriorly.

There is a slip of the hyohyoidei abductores to

the fifth branchiostegal ray. The interradialis is

very well developed, and the hypochordalis longitudinalis inserts only on the base of D 5. The

transversus caudalis has a more restricted origin

from the hypural plate dorsally, but a more extensive one anteroventrally. Both the flexor dorsalis superior and the flexor ventralis inferior are

better developed, and have a more extensive origin,

which includes the neural and haemal spines of

the penultimate vertebrae respectively.

Both the muscles to the swim bladder are better

developed, swim bladder "a" being more firmly attached to the lateral surface of the vertebral column medially.

Tetrosomus concatenatus (Bloch)

FIGURE 136

The subdivision of A 2 is not at all clear, and

A IP' is hardly distinguishable from A 13". The

levator arcus palatini is fairly small, and there is

no dorsal bundle of fibers to the dorsomedial face

of the tendon of the retrator arcus palatini. The

subdivisions of the sternobranchialis are not as

clear as in either of the previous species. Levator

internus II is extremely well developed, with a

broad insertion on infrapharyngobranchial 2. The

obliquus posterior is somewhat reduced. The hy-
NUMBER 155 45

pochordal longitudinalis inserts by a broad, undivided tendon on the bases of rays D 3—5, while

the transversus caudalis inserts on rays V 3—5.

Acanthostracion quadricornis (Linnaeus)

FIGURE 137

The sections of A 2 are well separated, and there

are two fiber directions in A 2a. A 13" is

well separated from the more ventral fibers, but

the other two portions are scarcely distinct. The

anterior bundle of fibers of the retractor arcus

palatini is well developed. The dilatator operculi

has an entirely tendinous insertion on the tip of

the dorsal process of the opercle, and the levator

arcus palatini is well developed.

The dorsolateral half of the protractor hyoidei

passes lateral to the interopercle to insert on the

dentary.

The interradialis partly overlies the tendons of

the hypochordal longitudinalis, and the transversus

caudalis inserts on rays V 3-5. The flexor dorsalis

superior and the flexor ventralis inferior are better

developed than in O. tuberculatus.

The epaxialis and the obliquus superioris insert

on the middle eight caudal fin rays (D 1-4 and

V 1—4), there being no tendons to D 5 or V 5.

The swim bladder musculature differs from O.

tuberculatus. The lateral and more posterior fibers pass dorsally and medially from their insertion

on the anterodorsal surface of the swim bladder to

their origin on the dorsolateral face of the vertebral

column. Anteriorly, the fibers tend to curve ventrally and then posteriorly from their origin on

the vertebrae, and lie medial to the outer, more

posterior fibers. This leaves a gap between the

ventromedial surfaces of the transverse posterior

fibers and the dorsolateral surface of the anterior

and more longitudinal fibers, giving rise to the

"hollow ball of muscles" (Tyler, 1963b: 159).

Summary of Ostraciidae

The main variation in this family is found in

the jaw and caudal fin musculatures. In the former,

the differences involve mainly the degree of subdivision of the adductor mandibulae, while in the

latter most variation is seen in the sites and number

of rays involved in the insertion of the hypochordal

longitudinalis and transversus caudalis. Apart

from this, this family is conservative in its myology.

Myological Description of the Representative Triodontid

The outline of Triodon, the monotypic representative of this family, is given in Figure 7. The

species inhabits the deeper waters (150-300 meters)

of the continental shelves of the Indo-Pacific. Almost nothing is known of the life history and

habits of this rare fish. Of the four specimens

dissected for this study, only one had anything in

its gut. This specimen (270 mm SL) contained the

remains of a number of echinoids (PClypeasteroidea), with occasional carapaces of shrimplike crustaceans. The lunate caudal fin, slender peduncle,

and poorly developed dorsal and anal fins suggest

that Triodon is a fairly fast swimmer, but there is

no direct evidence. The pelvic girdle is represented by a long, shaftlike bone, very similar to that

of the balistoids. The jaws are massive and beaklike, and form a powerful crushing apparatus, as

they do in all the remaining families except the

Canthigasteridae (although even here the basic

plan remains).

Triodon is usually considered to be the pleisomorph member of the gymnodonts (e.g., Tyler,

1962c), and to form a morphological intermediate

between them and the triacanthoids + balistoids

+ ostracioids.

Triodon macropterus Lesson

FIGURES 138, 139a, 140-145

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 138, 139, 140:

A 1, A 2a, A 23, A 3).—A 1 is a single, undivided

muscle which originates beneath the orbit as a flat,

aponeurotic sheath attached primarily to the anterodorsal face of the hyomandibular. It inserts on

the posteromedial face of the ventral half of the

maxilla. A 2 is separated into two parts by the

passage of ramus mandibularis V. A 2a originates

exclusively from the anterodorsolateral face of the
46 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

hyomandibular—a few fibers may attach to the

ventral face of the aponeurosis of A 1 posteriorly.

The extreme posterior fibers are covered laterally

by the dilatator operculi. A 2P, which lies beneath

A 2a, originates almost entirely from the dorsal

and lateral faces of the preopercle. The posterodorsal fibers overlie the posteroventral region of

A 2a. The two subdivisions insert together on the

medial face of the dentary above the Meckelian

fossa. A 3 is present at a thin sheet of fibers originating from the lateral metapterygoid and symplectic. It inserts medial to A 2 on the dentary

by a somewhat sheetlike aponeurosis. It is partially

confluent with A 2P posteriorly. A a> is well developed, and stretches along the medial surface of

the quadrate and anterior metapterygoid. It inserts by a flat aponeurosis on the dentary, lying

medial to the insertion of A 3.

LEVATOR ARCUS PALATINI (Figures 138, 140:

L.A.P.)—From a straplike origin on the ventral

sphenotic at the rear of the orbit, the muscle

passes downward to insert on the posterodorsolateral face of the hyomandibular. This point lies

medial to the dorsolateral flange of that bone,

which has developed in association with the origin

of A 2a. The fibers of the muscle fan out before

their insertion, this being particularly marked

anteriorly.

DILATATOR OPERCULI (Figure 138: D.O.).—Origin

is from the ventrolateral sphenotic and adjoining

pterotic. The muscle narrows to a tendon which

inserts on the enlarged anterodorsal process of the

opercle.

LEVATOR OPERCULI (Figure 138: L.O.).—This is a

broad, well-developed muscle, originating in the

groove between the pterotic and the large supracleithrum. It inserts broadly on the dorsomedial

face of the opercle. A small superficial aponeurosis is present on the midlateral face of the muscle.

ADDUCTOR ARCUS PALATINI (Figure 140: A.A.P.|

The muscle is confined to the floor and rear of the

orbit. Origin is from the lateral surface of the

parasphenoid. Anteriorly it inserts on the dorsomedial face of the mesopterygoid. There is a gap

where the fibers end in the tough connective tissue

lining the buccal cavity. Posteriorly, the fibers insert on the posterodorsal faces of the metapterygoid and hyomandibular.

ADDUCTOR OPERCULI (Figure 142: AD.OP.). The

muscle originates from the prootic beneath the

hyomandibular fossa ventral to, but dorsally continuous with, the origin of the adductor hyomandibulae. The fibers pass out laterally to insert on

the dorsomedial face of the opercle, just posterior

to its articulation with the hyomandibular.

ADDUCTOR HYOMANDIBULAE (Figure 142: A.H. ).—

The muscle originates from the ventrolateral

prootic just above the adductor operculi, and inserts as a more or less flattened sheet on the posterodorsomedial face of the hyomandibular.

MUSCLES OF THE HYOID REGION

VALVULUS.—The muscle is present as a thin, flattened sheet of fibers, arising from the dorsolateral

face of the protractor hyoidei at about the middle

of its length and grading into the tissues of the

buccal valve anterodorsally.

PROTRACTOR HYOIDEI (Figure 138: PR.HY.).—The

fibers arise from the posteroventromedial dentary

and insert on the posteroventral anterohyal and

the adjoining posterohyal. It completely covers

the first two branchiostegal rays, and is a long,

cylindrical muscle.

HYOHYOIDEUS INFERIORIS.—The fibers of this muscle are partially fused with those of the protractor

hyoidei. It arises from the ventral face of the

anterohyal, sharing, to some degree, aponeuroses

with the medial region of the protractor hyoidei.

The fibers pass anteromedially and fuse with their

antimeres. The muscle lies lateral to the origin

of the infracarinalis anterior, and there is some

intermingling of fibers with those of the protractor

hyoidei.

HYOHYOIDEI ABDUCTOREs (Figure 138: H.AB.).—The

muscle is made up of three slips. That to the first

ray originates from the medial face of the ventrohyal and inserts broadly over the ventromedial

face of the ray. The slip to the second ray arises

from the expanded dorsolateral surface of the first

ray, while that to the third ray originates from the

bases of the first and second rays.

HYOHYOIDEI ADDUCTORES (Figure 138: H.AD.).—

This is a well-developed sheet of muscle fibers. It

is firmly attached to the dorsomedial face of opercle

dorsally, and fades out in the wall of the opercular

chamber in the region of the dorsohyal anteroventrally.

STERNOHYOIDEUS.—The muscle is small, its origin

being confined to the anterodorsal tip of the ventral
NUMBER 155 47

part of the cleithrum, including a small fossa in

that bone. Anteriorly, the fibers sweep up to insert

on the ventral face of the ventrohyal.

VENTRAL BRANCHIAL MUSCLES

PHARVNCOCLAVICULARIS EXTERNUS (Figure 141:

PHC.E.).—This is a straplike muscle originating

from the lateral face of the cleithrum and inserting

on the anteroventral face of ceratobranchial 5. The

fibers pass posterodorsolaterally from their origin.

PHARYNGOCLAVICULARIS INTERNUS (Figures 141,

142: PHC.I.).—Orgin is from the anterodorsomedial

face of the cleithrum, the fibers passing anteriorly

to insert on the posterior face of ceratobranchial 5.

It is a flattened muscle.

OBLIQUI VENTRALES II, HI (Figure 141: OBL.V.).—

The anterior muscle connects the ventral faces of

the ceratobranchial and hypobranchial of the second arch. Obliquus III joins ceratobranchial 3 to

the ventral process of hypobranchial 3 and the

arch-shaped ligament.

TRANSVERSI VENTRALES rv, v (Figure 141: TR.V.).—

The anterior muscle connects the anteromedial

faces of the fourth ceratobranchials across the ventral midline. Transversus V is well developed, and

joins the anteromedial faces of the fifth ceratobranchials.

RECTI VENTRALES I, iv (Figure 141: RECT.V.).—

Rectus I is a fairly long, straplike muscle which

connects the dorsal face of the dorsohyal and the

ventrolateral face of the first ceratobranchial and

hypobranchial. Rectus IV arises from the anteroventral face of ceratobranchial 4 and passes anteromedially to attach to the posterior surface of the

arch-shaped ligament between the ventral processes

of the third hypobranchials.

RECTUS COMMUNIS (Figure 141: R.COMM.).—The

muscle originates anteriorly from the posterior face

of the urohyal. The fibers pass posteriorly, grading

into an aponeurosis at about the level of the third

basibranchial which inserts on the ventrolateral

face of ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I—IV (Figure 142: L.EXT.).—

The four muscles originate from the prootic just

anteroventral to the hyomandibular fossa. They

insert on the dorsal faces of epibranchials 1—4.

The first two muscles are not very well developed,

the fourth levator being the largest.

LEVATORES INTERNI II, HI (Figure 142: L.INT.).—

The muscles originate from the prootic beneath

the hyomandibular fossa, levator II having a more

medial origin than levator HI. The former inserts

partially on the medial face of infrapharyngobranchial 2 but mainly on the anteromedial face

of infrapharyngobranchial 3. Levator III inserts

on the dorsal face of infrapharyngobranchial 3.

OBLIQUUS DORSALIS HI (Figure 142: OBL.D.).—Two

heads of this muscle arise from the anterolateral

face of epibranchial 3. The fibers coalesce and

pass medially to attach to the posterodorsal face of

infrapharyngobranchial 3.

OBLIQUUS POSTERIOR (Figure 142: OBL.P.).—Fibers

pass from the dorsomedial face of ceratobranchial

5 to the posterior face of epibranchial 4.

TRANSVERSI DORSALES II, HI (Figure 142: TR.D.).—

The anterior muscle is well developed and partially

subdivided. The dorsal layer arises from infrapharyngobranchial 2 and the surrounding connective tissue. The fibers pass posteriorly and then

curve toward the midline just behind the basal

process of the parasphenoid, and join their antimeres. Beneath this, the ventral layer passes outward from the midline to attach to the anterolateral

face of epibranchial 4, the two layers separating

completely. Transversus III arises from the dorsal

midline and passes laterally to insert on the dorsal

face of the medial process of epibranchial 3.

RETRACTOR DORSALIS (Figure 142: D.RETR.).—The

muscle originates from the lateral face of the first

vertebra and passes anteriorly to insert on the

ventromedial faces of infrapharyngobranchials 3

and 4.

ADDUCTORES rv, v (Figure 142: AD.).—Adductor

IV is well developed, and connects the medial faces

of epibranchial 4 and ceratobranchial 4. Adductoi

V is less well developed, and passes from the anterodorsal tip of ceratobranchial 5 to the posterolateral face of epibranchial 4.

SPHINCTER OESOPHAGI (Figures 141, 142: s.o.).—

The anteroventral fibers of this muscle attach to

the ventromedial face of ceratobranchial 5. There

are two fairly distinct layers dorsally. The ventral

one arises from infrapharyngobranchial 2, the fibers passing posteriorly and then medially before

fading out in the connective tissue of the esopha-
48

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

gus. This is covered posterodorsally by the main

mass of the muscle, which does not extend anteriorly beyond the posteromedial face of epibranchial

4.

to insert on the extreme posterodorsal tip of the

cleithrum. The muscle is almost entirely covered by

the supracleithrum, and is closely associated with

the fibers of the epaxialis dorsally.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 1S8: ABD.S.).—

The muscle arises from the posteroventral surface

of the elongated cleithrum and inserts on the

anterolateral bases of the principal fin rays.

ABDUCTOR PROFUNDUS (Figure 138: ABD.P.).—

Origin is from the lateral face of the cleithrum.

The fibers insert on the posterolateral bases of the

principal rays and on that of the lateral half of

the vestigial fin ray.

ARRECTOR VENTRAUS (Figure 138: ARR.V.J. —The

muscle lies above the abductor superficialis and

originates from the lateral face of the cleithrum

beneath the flange. It inserts on the anterior face

of the medial half of the vestigial fin ray. There

may be a few fibers attaching to the lateral half of

the ray posteriorly.

ADDUCTOR SUPERFICIALIS (Figure 143: ADD.S.).—

The fibers originate from the anteromedial face of

the cleithrum and insert on the dorsomedial faces

of the principal rays distal to their bases. The

more ventrolateral fibers serve the more dorsal rays.

ADDUCTOR PROFUNDUS (Figure 143: ADD.P.).—The

muscle is well developed, and originates from the

medial face of the cleithrum and coracoid. It inserts on the ventromedial bases of the principal fin

rays, the tendons to the ventral two rays being

covered medially by the main mass of the muscle.

ARRECTOR DORSALIS (Figure 143: ARR.D.).—This is

a fairly small muscle, originating from the medial

face of the cleithrum and inserting on the base of

the medial half of the vestigial fin ray. It is partially covered medially by the adductor profundus.

CORACORADIALIS (Figure 143: COR.R.)._A somewhat flattened muscle, arising from the dorsal face

of the posterior process of the coracoid and inserting on the ventromedial face of the fourth radial.

PROTRACTOR PECTORALIS (Figures 138, 142: P.P.).

The muscle originates from the ventrolateral tip of

the pterotic and fans out posteroventrally to attach

to the dorsal region of the cleithrum.

LEVATOR PECTORALIS (Figure 138: TR.).—Origin is

from the posterior face of the pterotic. The fibers

pass mainly posteriorly, but also somewhat laterally,

MUSCLES OF THE DORSAL FIN

INCLINATORES DORSALES (Figure 144: INC.).—Each

fin ray possesses an inclinator which arises in the

fascia between the skin and the epaxialis and inserts on the lateral base of the fin ray a little dorsal

to the insertions of the erector and depressor muscles. The inclinators decrease in size posteriorly.

ERECTORES DORSALES (Figure 144: EREC).—There

are two small, anterior erectors, which originate

from the lateral faces of the first two pterygiophores

and insert on the bases of the spines of the spiny

dorsal fin. Each fin ray has an erector inserting on

its anterolateral base. These muscles arise from the

lateral faces of the pterygiophores and the neural

spines and centra of the eighth to fourteenth vertebrae.

DEPRESSORES DORSALES (Figure 144: DEPR.).—The

first dorsal spine only has a depressor muscle,

which originates from the lateral base of the first

pterygiophore and inserts on the posteroventral

base of the spine. Each ray in the soft dorsal fin has

a depressor inserting on its posterolateral base. Origin is as for the erectors, the depressor to each ray

lying just behind the erector.

SUPRACARINAUS ANTERIOR.—This is a welldeveloped muscle arising from the posterior and

lateral faces of the supraoccipital. The fibers pass

posteriorly to attach to the anterior face of the first

pterygiophore. There is some intermingling of

fibers from the left and right sides in the midline.

SUPRACARINALIS POSTERIOR (Figures 144, 145: s.

POST.).—The muscle stretches from the posterior

face of the last pterygiophore of the dorsal fin and

the neural spine of the fourteenth vertebra to the

anterodorsal regions of the neural spines of the

third and fourth last vertebrae.

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES (Figure 144: INC.).—An inclinator arises from the fascia over the obliquus

inferioris and inserts on the anterolateral base of

each fin ray. The medial fibers of the more anterior

inclinators attach to the myocommata of the
NUMBER 155 49

obliquus superioris, making separation of the muscle difficult. In addition, there is a large, residual

inclinator inserting on the anteroventrolateral base

of the first pterygiophore. Its ventromedial region

is more or less continuous with the ventral fibers of

the obliquus inferioris.

ERECTORES ANALES (Figure 144: EREC).—These

muscles, which insert on the anterolateral bases of

the anal fin rays, originate almost entirely from

the lateral faces of the pterygiophores, with only a

few fibers from the tips of the haemal spines of

the associated vertebrae.

DEPRESSOR re ANALES (Figure 144: DEPR.).—Origin

is as for the erectors, the depressor of each fin ray

inserting on the posterolateral base of the ray.

INFRACARINALIS ANTERIOR (Figure 138: INF.A.).—

This is a well-developed muscle which originates

from the anteroventral tip of the cleithrum and

inserts in the anteroventral groove in the pelvis.

Evidence of its originally paired nature is visible

externally, but the deeper fibers of either side have

fused in the midline.

INFRACARINALIS MEDIUS (Figure 138: INF.M.).—A

fairly well-developed section, which attaches to the

ventrolateral face of the pelvis just anterior to the

middle of its length. It grades into the obliquus

inferioris at about the level of the postcleithrum,

the more posterolateral fibers intermingling somewhat with those of the residual inclinator analis.

INFRACARINALIS POSTERIOR (Figures 144, 145: INF.

P.).—The muscle arises from the posterolateral

faces of the last anal pterygiophore and the haemal

spine of the fifteenth vertebra and attaches to the

anteroventral face of the haemal spines of the third

and fourth last vertebrae.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 145a: INT.).—The muscle

is developed between the middle twelve caudal fin

rays. The fibers span a few rays between their sites

of attachment. Those of the dorsal rays pass anteroventrally, while those of the ventral rays pass

anterodorsally.

HYPOCHORDAL LONGITUDINALIS (Figure 1456:

H.L.).—The muscle is well developed, and originates

from the dorsolateral face of the ural centrum, and

the lateral faces of the hypurals 1 and 2, parhypural, and hypurapophysis. The muscle inserts on

the bases of rays D 3-5.

FLEXOR DORSALIS (Figure 145c: F.D.).—Origin is

restricted to the lateral faces of the epural, the first

uroneural and the dorsal crest of the ural centrum

The tendons insert on the bases of rays D 2-6.

FLEXOR DORSALIS SUPERIOR (Figures 1456/r: F.D.

s.).—The muscle originates from the lateral faces

of the epural and the neural spines of the second

and third last vertebrae. Insertion is on the lateral

base of ray D 7.

FLEXOR VENTRALIS (Figure 145c: F.V.).—The muscle is fairly well developed, and lies beneath the

flexor ventralis externus. Origin is from the lateral

faces of the centra and haemal spines of the last

three vertebrae (including the ural centrum), the

parahypural, and the hypurapophysis. The muscle

inserts on the bases of rays V 1-7.

FLEXOR VENTRALIS EXTERNUS (Figure 145c: F.V.

E.).—The fibers arise from the lateral faces of the

centra and haemal spines of the third and fourth

last vertebrae and pass posteriorly to insert on the

bases of rays V 1-2.

FLEXOR VENTRALIS INFERIOR (Figure 1456^: F.V.

L).—Origin is primarily from the lateral face of the

haemal spine of the penultimate vertebra, the

muscle inserting on the lateral base of V 7.

TRANSVERSUS CAUDALIS (Figure 145c: TR.C).—The

muscle is poorly developed. It originates from the

lateral face of the fourth hypural and inserts on

the dorsal base of ray V 1.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 138, 145a,b: EPAX.). — The

subdivision of this muscle into dorsal and ventral

moieties is incomplete, particularly medially.

Anteriorly, the dorsal section attaches to the posterodorsal faces of the frontal, epiotic, pterotic,

supraoccipital, and exoccipital. The myocommata

become increasingly oblique posteriorly until they

are almost horizontal (behind the dorsal fin). Anteromedially, some of the fibers arise from the

neural spines and centra of the vertebrae and the

pterygiophores. Posteriorly, the fibers grade into a

flattened tendon which joins a similar tendon from

the obliquus inferioris. Together, these two tendons

form an aponeurotic sheath inserting on the bases

of all the procurrent and principal caudal fin rays.

The ventral section of the epaxialis is virtually continuous with the obliquus superioris. The fibers

arise anteriorly from the posterior faces of the
50

pterotic and exoccipital. In the posterior region the

muscle inserts on the lateral bases of rays D 1-6,

the more ventral tendons passing medial to the

hypochordal longitudinalis.

OBLIQUUS SUPERIORIS (Figures 138, 145a,b: OBL.

s.).—This section arises anteriorly as a small slip

of fibers from the posterodorsal tip of the cleithrum. It fans out posteroventrally, attaching to

and between the pleural ribs, with the ventral

fibers intermingling with the obliquus inferioris.

Behind the anal fin, these two sections are relatively well separated. It inserts tendinously on the

bases of rays V 1-6. A large bundle, which appears

to be mostly continuous with the obliquus superioris, but which also receives fibers from the epaxialis, passes somewhat dorsally in the peduncular

region to insert on the lateral crest of the ural

centrum. It is slightly overlain posteriorly by the

hypochordal longitudinalis. It is somewhat reminiscent of a proximalis muscle, but is not separated

from the body muscles.

OBLIQUUS INFERIORIS (Figures 138, 144, 145a:

OBL.I.).—The muscle has a number of subsections.

The anteroventral section arises from the posterior

and posteroventral faces of the coracoid and cleiSMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

thrum, and attaches to the anteroventral face of

the postcleithra. Two vague myocommata are present, and occasional fibers are to be found in the

connective tissue between the ventral border of

this section and the infracarinalis medius below

it. A thin sheet of fibers passes obliquely upward

from the posterodorsal faces of the postcleithra

and fades into the fascia overlying the obliquus

superioris. Posteroventrally, the fibers become more

horizontally oriented, and intermingle with those

of the obliquus superioris, infracarinalis medius,

and residual inclinator analis. Myocommata, which

are continuous with those of the obliquus superioris, are present in the fibers behind the postcleithra. From the ventromedial surface of the

posterior myocommata of the eleventh myomere,

and closely associated with the medial faces of

the infracarinalis medius and the rest of the obliquus inferioris, there arises a short bundle of

fibers which passes posterodorsomedially to insert

tendinously on the anteroventral face of the haemal

spine of the fourteenth vertebra. The fibers pass

medial to the obliquus superioris but lateral to the

erectores and depressores anales.

Myological Descriptions of Representative Tetraodontids

The members of this family (see Figure 8 for

general outline) as recognized here contain ten

genera (representatives of six genera were dissected

for this study), which were divided into four families by Fraser-Brunner (1943). Although his families may well represent distinct phyletic lines, the

status accorded them by Fraser-Brunner has not

been followed by other workers (e.g., Tyler, 1970a).

The skin is smooth or covered with small prickles, and the fish are capable of considerable

inflation when threatened. Some forms have an

almost lunate caudal fin (e.g., Lagocephalus), but

a rounded caudal is more common. Dorsal and

anal fins are usually small, and normally beat

synchronously from side to side. The pectoral fins

are large, and often used in locomotion. The powerful beaklike jaws are well adapted for crushing

the mollusks and brachyurans which form a major

part of the puffer-fish diet. They are generally

tropical to subtropical in distribution (with a few

fluviatile forms), and are commonly found over

sea-grass meadows, sandy bottoms, and the adjoining coral reefs.

The family is considered to be closely related to

the Canthigasteridae (which latter has often been

included in the Tetraodontidae), and also close

to the Diodontidae.

Lagocephalus lunaris (Bloch and Schneider)

FIGURES 1396, 146-155

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 1396, 146, 147,

148, 149: A la, A IP, A 2a, A 2P, A 3)._A 1 consists of two well-developed sections. A IP has a

complicated fiber structure. Fibers originating from

the lateral faces of the palatine, vomer, and ethmoid pass ventrolaterally. They form a bipinnate

structure with the fibers arising from the anterior

face of the prefrontal (which pass ventromedially).
NUMBER 155 51

Fibers from the ventrolateral tip of the prefrontal

course anteroventrally, the fibers from the ventral

face of that bone at first pass ventrally, and then

(as they become more posterior in origin) anteroventrally. The ventral surface is largely aponeurotic. Beneath this, another bundle of fibers is

present, arising from the lateral parasphenoid. It

is well separated from the above-mentioned aponeurosis posteriorly, but grades into it anteriorly. The

muscle inserts on the dorsomedial faces of the premaxilla and maxilla. A 1 a is smaller. It originates

from an aponeurosis on the floor of the orbit (attaching posteriorly to the hyomandibular medial

to A 2 a) and from a small head on the posterolateral preopercle. Insertion is on the posteromedial

face of the maxilla. A 2a is very well developed

and is expanded ventrally to originate from two

heads. The anteroventral one arises from the quadrate, symplectic, lateral preopercle, and the anteroventral tip of the hyomandibular. The other head

arises from the dorsolatera"l preopercle and posterolateral hyomandibular. There is a considerable

variety of fiber direction. Anteriorly, a tough

aponeurosis joins A 23. The section lies lateral

to ramus mandibularis V apart from a small fiber

bundle from the dorsolateral quadrate. A 23,

which lies medial to the above nerve, has shifted

dorsally in origin, and lies above A 3. It originates

from the lateral parasphenoid and prootic. The

fibers pass laterally and anteroventrally to grade

into a tendinous aponeurosis which joins that of

A 2 a. The two sections insert on the medial face

of the dentary. A 3 is a distinct muscle arising

from the lateral faces of the metapterygoid, quadrate, and ectopterygoid and inserting by a flat,

tendinous aponeurosis on the dorsal surface of

Meckel's cartilage. A co is a small muscle (Figures

147, 149). It arises from the anteromedial edge of

the ectopterygoid and inserts on the ventral rim

of the Meckelian fossa. It lies medial to the tendon

of A 3.

LEVATOR ARCUS PALATINI (Figures 146, 147:

L.A.P.).—The fibers of this muscle are continuous

dorsolaterally with the dilatator operculi. Origin

is from the ventrolateral tip of the frontal, and

the fibers fan out to insert in the fossa on the

posterodorsal face of the hyomandibular, just anterior to the articulation with the skull.

DILATATOR OPERCULI (Figure 146: D.O.).—This

muscle is very well developed. The anterior fibers

are almost parallel, but the muscle becomes bipinnate posteriorly. Origin is from the lateral faces

of the frontal and sphenotic, and the dorsolateral

hyomandibular about its articulation with the

skull. Insertion is on the dorsolateral opercle,

mainly around the strong, dorsoventrally oriented

arista, but also on the anterolateral surface of the

bone. It is overlain dorsally by an aponeurotic

sheath from the epaxialis. Anterolaterally, a strap

of muscle fibers attaches to the posteroventral face

of the preopercle.

LEVATOR OPERCULI (Figure 146: L.O.).—This is

a flattened muscle, which arises from the anteroventrolateral pterotic and the ventrolateral face of

the posterior process of the frontal. It inserts on

the posterodorsal face of the opercle and its crista.

Some of the ventral fibers are closely associated

with the dorsal fibers of the protractor pectoralis.

ADDUCTOR ARCUS PALATINI (Figures 147, 148:

A.A.P. ).—The muscle is extensively developed,

particularly anteriorly. It originates from the anteroventral prootic, lateral parasphenoid, and posteroventrolateral vomer. The fibers beneath the

vomer stretch across the midline. Insertion is on the

medial face of the palatine, and the dorsomedial

faces of the ectopterygoid, metapterygoid, and hyomandibular.

ADDUCTOR OPERCULI (Figures 147, 150: AD.OP.).—

The muscle originates from the anteroventral face

of the pterotic and passes outward as a thin sheet

to insert on the dorsomedial face of the opercle

just medial to the insertion of the levator operculi.

MUSCLES OF THE HYOID REGION

VALVULUS (Figure 149: VA.).—The muscle,

which is not fully separated from the protractor

hyoidei posteriorly, arises from the anteroventral

surface of the interopercle. It passes anteriorly,

and then curves upward to face out in the tissues

of the mandibular buccal valve.

PROTRACTOR HYOIDEI (Figure 146: PR.HY.).—Origin is from the ventral margins of the dentary,

angular, anterior preopercle, and interopercle. The

fibers insert on the lateral faces of branchiostegal

rays 2-4, and the anterohyal between these rays.

The more posterior fibers tend to course more

toward the midline from their sites of insertion.

HYOHYOIDEI ABDUCTORES (Figures 146, 150: H.

AB.).—A bundle of fibers passes posteroventrally
52

from the base of the second ray to the medial faces

of the third and fourth rays. The section serving

the second ray arises from the posterior face of

the lateral process of the enlarged first ray. The

muscle to the first ray is massively developed. The

ray forms a flat, horizontal plate extending posteriorly from the anterohyal, which lies lateral to

it. The muscle has a large number of fiber directions. The ventral surface of the ray gives rise to

a large bundle of fibers that pass anteriorly and

a little dorsally to originate from the ventral and

lateral anterohyal. The more lateral fibers, including those from the lateral process of the ray, tend

to sweep anterodorsally, and then medially to the

midline, where they join their antimeres. A large

volume of fibers inserts on the dorsomedial face of

the ray. They originate from the fascia overlying

the sternohyoideus, the lateral face of the first

basibranchial and the medial anterohyal. Most of

these fibers, however, arise from the midline, where

they join with their antimeres. Although undoubtedly functioning as two muscles, there is no physical hiatus, and the fibers from the two bundles

intermingle to a considerable extent. The posterodorsomedial edge of the ray gives rise to a small

bridge of fibers across the midline, which lies beneath the ventral branchial musculature at about

the level of the third basibranchial.

HYOHYOIDEI ADDUCTORES (Figures 146, 147, 150:

H.AD.).—The muscle is somewhat subdivided. The

main mass passes dorsoventrally in the lateral wall

of the opercular cavity, with a dorsal bundle attaching to the dorsomedial face of the hyomandibular. Ventrally, the fibers (to which the medial

faces of branchiostegal rays 2-6 attach) pass anteromedially to meet another sheet of fibers from

the medial floor of the opercular cavity, the latter

passing anterolaterally. Posterolaterally, a bundle

arises from the posteroventral face of the supracleithrum and a myocomma with the anterior part of

the obliquus inferioris. These fibers pass anteroventrally and then posteroventrally in a semicircle

to attach ventrally to the dorsolateral tip of the

coracoid. From the anteroventral margin of this

semicircle, a bundle passes anteriorly to attach

along the ventrolateral surface of the cleithrum.

Anterodorsally, fibers from this arch are continuous

with the rest of the muscle. Posterodorsomedially,

a bundle passes upward to grade into the posterior

fibers of the levator externus IV.

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

STERNOHYOIDEUS (Figures 146, 150: STH.).—The

muscle is somewhat, conical, and is poorly developed. It originates from the anteroventral tip of

the cleithrum and inserts on the dorsomedial face

of the anterior region of the anterohyal.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 150,

151: PHC.E.).—Origin is from the ventromedial face

of the cleithrum, the fibers passing dorsally to insert on the anteroventral face of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERN US (Figures 150,

151: PHC.L).—The muscle arises from the medial

face of the cleithrum, and consists of two sections.

The anterior section passes anterodorsally, medial

to the pharyngoclavicularis externus, to insert on

the posteroventral face of basibranchial S. The

more medial fibers of this section join their antimeres in a midventral raphe, while some of the

more dorsal ones arise from ceratobranchial 4 and

pass to basibranchial 3. The more posterior section

arises from the anteroventromedial cleithrum and

inserts on the ventral face of ceratobranchial 5.

OBLIQUUS VENTRAUS HI (Figure 151: OBL.V.).—

The muscle originates from the anteroventral region of ceratobranchial 3 and the posteroventral

tip of hypobranchial 3. The fibers pass anteromedially to join with the fibers of rectus IV in an

insertion on the anteroventral process of hypobranchial 3.

TRANSVERSI VENTRALES IV, v (Figure 151: TR.V.).—

These muscles connect the anteromedial faces of

the ceratobranchials of the fourth and fifth arches

across the ventral midline. Both muscles are small.

RECTI VENTRALES i-rv (Figures 150, 151: RECT.

v.).—Rectus I is well developed, passing from the

dorsolateral face of the anterohyal to the anterolateral surface of hypobranchial 1. The lateral surface of the muscle gives rise to a bundle of fibers

passing posterodorsally, which grade into a tendon

attaching to the ventromedial face of the hyomandibular just lateral to its articulation with the

skull. Recti II and III connect the hypobranchials

of the first and second and second and third arches

respectively. Rectus IV passes from the anteroventral face of ceratobranchial 4 to the posterior face

of the ventral process of hypobranchial 3. The

anterodorsolateral fibers are continuous with the

anteromedial fibers of obliquus ventralis III.
NUMBER 155 53

RECTUS COMMUNIS (Figure 151: RXOMM.).—The

muscle arises from the posterior face of the ventrohyal. It passes posteriorly as a tendon, and develops

fibers at the level of hypobranchial 1, where it splits

into left and right halves. The fibers then pass posteriorly, and grade into tendon at the level of

ceratobranchial 4. The tendon inserts on the ventrolateral face of ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERN I I-IV (Figure 150: L.EXT.).—

These muscles originate from the ventral faces of

the prootic and pterotic beneath the hyomandibular fossa. Levator I inserts on the dorsolateral

face of epibranchial 1, with a few posterior fibers

passing to the anteroventral face of epibranchial

2. Levator II inserts on the dorsolateral faces of

epibranchials 2 and 3, and apparently represents

fusion with the third levator. Levator IV is well

developed. It inserts along the dorsal length of

epibranchial 4, and continues in the wall of the

opercular cavity behind the bone, reaching the

dorsomedial face of the cleithrum.

LEVATORES INTERNI II, HI (Figure 152: L.INT.).—

These muscles have altered somewhat from the

usual condition. Levator II originates from the

posteroventromedial face of the pterotic. It passes

anteroventrally to insert partly on the dorsomedial

face of infrapharyngobranchial 3, and partly on

the dorsolateral face of infrapharyngobranchial 2.

The medial face of the muscle shares a strong

aponeurosis with the dorsolateral fibers of transversus dorsalis HI. Behind this, the muscle passes

medial to levator III to its origin. Levator III

originates from the ventrolateral sphenotic beneath

the hyomandibular fossa. It passes ventrally to

insert on the anterodorsolateral face of infrapharyngobranchials 2 and 3.

OBLIQUUS DORSALIS HI (Figure 152: OBL.D.).—A

fairly well-developed muscle, which passes anteromedially from the dorsomedial faces of epibranchials 3 and 4 to the posterodorsal face of

infrapharyngobranchial 2.

OBLIQUUS POSTERIOR (Figure 150: OBL.P.).—The

muscle appears to be present, but is not clearly

separated from the sphincter oesophagi.

TRANSVERSI DORSALES II, HI (Figure 152: TR.D.).—

In transversus II, the fibers arise from the ventrolateral face of the parasphenoid. The posterior

fibers almost intermingle with the anterior fibers

of the lateral bundle of the sphincter oesophagi.

The main mass of the fibers passes laterally and

then curves anteriorly. Dorsolaterally, a strong

aponeurosis attaches to the medial face of levator

internus II. The ventrolateral fibers attach to the

dorsal faces of epibranchials 1 and 2 and infrapharyngobranchial 1. The more anterior fibers pass

medially to a middorsal raphe, and are not attached to the skull. Posteriorly, the muscle gives

rise to a bundle that passes laterally into the posterodorsal wall of the opercular cavity. Transversus

III is a well-developed muscle, which passes across

the dorsal midline between the third and fourth

epibranchials of either side. It lies ventral to transversus II, which covers it both anteriorly and posteriorly.

RETRACTOR DORSALIS (Figure 152: D.RETR.).—

Origin is from the lateral and ventrolateral faces

of vertebrae 1 and 2. The fibers course anteroventrally, fuse briefly with their antimeres in the

midline, and insert on the posteromedial faces of

infrapharyngobranchials 2 and 3. It is overlain

dorsally by a small bundle of the sphincter oesophagi.

ADDUCTORES I-V (Figures 150, 151, 152: AD.).—

Adductors I—III all connect the anteromedial faces

of ceratobranchials 1-3 to the anterolateral faces

of epibranchials 1-3. Adductor IV connects the

medial faces of ceratobranchial 4 and epibranchial

4. Adductor V passes from the lateral region of

ceratobranchial 5 to the posterior face of epibranchial 4.

SPHINCTER OESOPHAGI (Figures 150, 151, 152:

s.o.).—The muscle has a very complicated form.

Ventrally, two longitudinal bundles arise from the

posterior face of basibranchial 3. They fuse at the

level of ceratobranchial 5, and form a longitudinal

sheath on the floor of the esophagus. Beneath this,

a thick, almost transverse bundle connects the

medial faces of the fifth ceratobranchials. Ventral

to the latter bundle is a thin sheet of fibers, also

between the fifth ceratobranchials posteriorly, but

becoming longitudinally oriented and fading out

above transversus ventralis V. Dorsally, three

bundles pass anteriorly beneath the infrapharyngobranchials, attaching to the ventromedial faces of

infrapharyngobranchials 1-3. They fade out posteriorly in the tissue of the esophagus. The muscle

passes across the midline below the retractor dor-
54

salis posteriorly, except for a small bundle of

fibers lying above and in front of the retractor.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figures 146, 150: ABD.

s.). — The muscle originates from the posterior,

medial, and lateral faces of the cleithrum. It passes

posteriorly to insert on the lateral faces of the

anterodorsal processes of the bases of the principal

fin rays.

ABDUCTOR PROFUNDUS (Figure 150: ABD.P.).—The

muscle originates from the posteroventral cleithrum and lateral faces of the coracoid and actinosts. It inserts on the ventrolateral bases of the

principal rays and the lateral base of the lateral

half of the vestigial ray.

ARRECTOR VENTRALIS (Figure 146: ARR.V.).—Origin is from the ventrolateral face of the dorsal

region of the cleithrum. The muscle inserts on the

anterolateral base of the medial half of the vestigial fin ray.

ADDUCTOR SUPERFICIALIS (Figure 153: ADD.S.).—

The muscle originates from the dorsomedial cleithrum. The fibers to the dorsalmost rays pass posteriorly, the slip to each succeeding ray passing

increasingly ventromedially. Thus, the slip to the

ventralmost ray passes ventrally, and lies medial to

all the others. The ventral six rays have dorsal

processes, to which the tendons attach, the more

dorsal tendons inserting on the dorsomedial faces

of the rays distal to their bases.

ADDUCTOR PROFUNDUS (Figure 153: ADD.P.).—The

muscle originates from the medial faces of the

coracoid and the radials, and inserts on the posteromedial flanges of all but the six ventral rays, where

insertion is on the ventromedial shaft of the ray.

ARRECTOR DORSALIS (Figure 153: ARR.D.).—The

muscle is small, arising from the medial face of

the scapula, and inserting on the medial face of

the medial half of the vestigial fin ray.

CORACORADIALIS (Figure 153: COR.R.).—The muscle is poorly developed. It passes from the dorsomedial face of the posterior coracoid process to the

posteroventral face of the fourth radial.

PROTRACTOR PECTORALIS (Figure 146: P.P.).—From

its origin on the ventrolateral pterotic, the muscle

passes ventrally to the anteromedial face of the

supracleithrum and the posterodorsal cleithrum.

LEVATOR PECTORALIS (Figure 146: TR.).—The

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

fibers pass from the posteroventral face of the

pterotic to the extreme dorsolateral tip of the cleithrum medial to the supraclei thrum.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORS ALES (Figure 154: INC.).—The

muscles are represented by a flat sheet of transverse

fibers. They have lost their association with the

fin rays, and now form the dorsal part of the

transverse cutaneous system.

ERECTORES DORSALES (Figure 154: EREC).—The

erectors originate from the lateral faces of the

pterygiophores and neural spines, and the dorsolateral faces of the sixth to thirteenth centra. They

insert on the anterolateral bases of all the fin rays

(including the small first ray).

DEPRESSORES DORSALES (Figure 154: DEPR. ).—

These muscles arise in the same area as the erectors,

and insert on the posterolateral bases of all the

fin rays.

SUPRACARINALIS ANTERIOR (Figures 146, 154: s.

ANT.).—The muscle is well developed, and arises

from the posterior faces of the supraoccipital and

epiotic. It passes posteriorly to attach to the anterolateral face of the first dorsal pterygiophore.

SUPRACARINALIS POSTERIOR (Figures 154, 155: s.

POST.).—The fibers arise from the posterodorsal

face of the last dorsal fin pterygiophore, and attach

to the dorsolateral faces of the neural spines of the

next three vertebrae to end on the neural spine of

the seventeenth vertebra.

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES (Figures 146, 154: INC.).—

The residual inclinator arises from the posteroventral tip of the postcleithrum and attaches to

the lateroventral face of the first pterygiophore of

the anal fin. The first inclinator of the fin is well

developed, but all the others are poorly so, and do

not insert on the fin rays, but on the cartilagenous

distal pterygiophores. These muscles arise from the

fascia over the obliquus inferioris.

ERECTORES ANALES (Figure 154: EREC).—The

muscles originate from the lateral faces of the

pterygiophores and the haemal arches and spines

of the ninth to thirteenth vertebrae, inserting on

the anterolateral bases of all the fin rays.
NUMBER 155 55

DEPRESSORES ANALES (Figure 154: DEPR.).—The

depressors arise just behind the erectors to any

particular ray, but insert on the posterolateral

bases of the rays.

INFRACARINALIS ANTERIOR.—The muscle is apparently represented by fibers arising from the

ventral tip of the cleithrum and passing posteriorly

in the subdermal tissue to intermingle with those

of the infracarinalis medius, helping to form the

longitudinal cutaneous system.

INFRACARINALIS MEDIUS (Figures 146, 154: INF.

M.).—It seems likely, as discussed above, that this

muscle forms part of the longitudinal cutaneous

system. It arises from the first pterygiophore of the

anal fin and passes anteriorly into the subdermal

tissue.

INFRACARINALIS POSTERIOR (Figures 154, 155: INF.

P.).—The muscle arises from the posteroventral

face of the last anal pterygiophore and its posterior

process. Fibers attach to the ventrolateral faces of

the haemal spines of the fourteenth to sixteenth

vertebrae, ending on the spine of the seventeenth

vertebra.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 155a: INT.).—The muscle

passes toward the midline from the lateral faces

of the caudal rays, a little distal to their bases. The

fibers are superficially continuous.

HYPOCHORDAL LONGITUDINALIS (Figure 155:

H.L.).—This muscle originates from the dorsal surface of the ridged parhypural and the lateral faces

of the ventral fused hypurals, as well as from the

ural centrum. It inserts on the ventrolateral faces

of rays D 3 and 4.

FLEXOR DORSALIS (Figure 155&: F.D.).—Origin is

from the dorsolateral faces of the third and fourth

last vertebral centra and the anterolateral face

of the epural. The tendons insert on the anterolateral bases of rays D 1-4.

FLEXOR DORSALIS SUPERIOR (Figure 155: F.D.S.).—

A well-developed muscle, originating from the dorsolateral faces of the thirteenth to fifteenth vertebral centra. The fibers give rise to a tendon which

joins its antimere before inserting on the anterodorsal base of D 5.

FLEXOR VENTRALIS (Figure 1556: F.V.). — The

muscle originates from the ventrolateral face of

the hypural plate, the ural centrum, and the centrum and haemal spine of the penultimate vertebra.

It inserts on the bases of rays V 3 and 4.

FLEXOR VENTRALIS EXTERNUS (Figure 155b: F.V.

E.).—The fibers arise from the ventrolateral faces

of the centra and haemal spines of the second and

third last vertebrae and insert on the bases of rays

V 1 and 2.

FLEXOR VENTRALIS INFERIOR (Figure 155: F.V.L).—

Origin is from the ventrolateral faces of the centra

of the thirteenth to fifteenth vertebrae. The fibers

give rise to a tendon which meets its antimere

before inserting on the base of ray V 5.

TRANSVERSUS CAUDALIS (Figure 155fc: TR.C).—The

muscle arises from the ventral face of the epural

and the lateral surface of the upper part of the

hypural plate. It passes posteroventrally as a thin

tendon to insert on the dorsolateral face of ray

VS.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 146, 154, 155a: EPAX.).—

Anteriorly, the muscle is attached to the posterior

faces of the supraoccipital, exoccipital, pterotic,

epiotic, frontal, and supracleithrum. Fibers also

arise from the lateral faces of the neural spines

and centra of the vertebrae. The dorsal moiety is

well separated from the main mass at about the

level of the dorsal fin. It passes posteriorly, becoming increasingly aponeurotic, and eventually forms

a flat, sheetlike tendon which joins a similar tendon from the obliquus inferioris to insert on the

lateral bases of all the caudal fin rays. The anterior

region covers the anterior part of the obliquus

superioris. Fiber direction superficially tends to

be from anteroventral to posterodorsal. A few of

the ventromedial fibers attach to the peritoneum

overlying the swim bladder near the vertebral centra. Posteriorly, the fibers grade into a flat aponeurosis which inserts on the lateral bases of rays D

1-4.

OBLIQUUS SUPERIORIS (Figures 146, 154, 155a:

OBL.S.).—The muscle arises from the posterodorsal

tip of the cleithrum. It broadens out rapidly,

becoming closely associated with the epaxialis dorsally and the vertebral centra and haemal spines

medially. Posteriorly, it grades into an aponeurosis

which inserts on the lateral bases of rays V 1-4.

OBLIQUUS INFERIORIS (Figures 146, 154, 155a;

OBL.1.).—The anteroventral section consists of two
56

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

well-separated parts. The dorsal one connects the

anteroventral face of the postcleithrum to the

posterior and ventral faces of the coracoid. Beneath this, the ventral part passes back from the

posteroventral cleithrum and coracoid to attach to

the medial face of the postcleithurm via the third

myocomma, the more posterior fibers being continuous with the anterodorsal part. The anterodorsal

portion arises from the fascia overlying the epaxialis,

being partly overlain itself by the superficialis

lateralis. The fibers attach to the posterodorsal

face of the postcleithrum, the more medial ones

being continuous with those of the anteroventral

section. Posteriorly, the fibers become increasingly

horizontally oriented, most of them attaching to the

ventrolateral face of the first anal pterygiophore.

Some of the posterior fibers join to a myocomma of

the deeper section of the obliquus inferioris. This

deeper part is continuous anteriorly with the fibers

of the infracarinalis medius, and now forms the

longitudinal cutaneous system. A small bundle of

fibers passes posterodorsomedially from this part of

the muscle. It soon grades into a tendon which

courses lateral to the erector-depressor complex of

the anal fin to attach to the anteroventral tip of

the haemal spine of the twelfth centrum.

CUTANEOUS MUSCULATURE

This system, which lies immediately below the

skin, is very complicated and difficult to follow.

These difficulties arise largely because of the

numerous elastic connective tissue fibers which intermingle with the muscle fibers. Owing to the

difficulty in following the system, only cursory

attention will be paid to it. The fibers pass in two

main directions, transverse and longitudinal, of

which the transverse is the more superficial. The

fibers are concentrated in the regions where the

spines or prickles are best developed—mainly along

the stomach and back. The central bases of the

spines are closely associated with the muscle

fibers, but histological sections are necessary to

determine whether the fibers actually insert on

these bases. Transverse fibers are also present behind the dorsal and anal fins, across the midline

of the skull, and beneath the eye. The ring of

fibers encircling the mouth in the tissues of the

lips may also be derived from this system. A welldeveloped bundle of fibers passes anteriorly from

the dorsal region of the prefrontal to the lips, where

it is joined by another bundle arising from the

anteroventral corner of the eye.

The longitudinal system is best developed ventrally, between the anus and the lower jaw. This

part of the system presumably arose from the fibers

of the infracarinales anterior and medius after the

loss of the pelvis, while the transverse system may

have been initially derived from the inclinators of

the dorsal and anal fins. There is an enigmatic

bundle (present in this species only of those examined) which arises from the peritoneum overlying

the swim bladder and passes anterolaterally between the posterodorsal tip of the cleithrum and

the anterior margin of the obliquus inferioris. It

grades into the connective tissue overlying the

dilatator operculi.

Amblyrhynchotes honckenii (Bloch)

FIGURE 156

A lo completely covers A 2o posterodorsolaterally. The ventral bundle of A 13 is well developed, and

reaches as far as the rear of the orbit posteriorly.

The separation of the two bundles of A 2a is

more distinct, and A 23 is not as well developed.

The anterolateral bundle of the dilatator operculi

inserts on the anterodorsal face of the opercle and

subopercle.

The pharyngoclavicularis externus consists of two

parts, the anterior inserting on basibranchial 3

(where it is partly confluent with the pharyngoclavicularis internus), the posterior part inserting

on the anteroventral face of ceratobranchial 5. The

obliquus posterior is well developed, and distinct

from the sphincter oesophagi. The inclinator analis

to the first ray now inserts on the cartilagenous

distal pterygiophore and not on the base of the

first ray. The infracarinalis medius is somewhat

distinct. It attaches anteriorly to the posteroventral

tip of the cleithrum, and becomes continuous with

the longitudinal cutaneous in the midregion. It

separates from the cutaneous again posteriorly to

attach to the first anal pterygiophore. The hypochordal longitudinalis inserts on rays D 2-4, while

the transversus caudalis inserts on rays V 2-3.

Colomesus psittacus (Bloch and Schneider)

FICUIUE 157

A la and A 13 are as for A. honckenii. A 2a,
NUMBER 155 57

which is not particularly well separated into two

heads, has a high dorsal origin from the ventral

surface of the lateral process of the hyomandibular,

and has increased in bulk. A 2P has expanded

across what was the dilatator fossa, and extends its

origin posterodorsally onto the sphenotic, the

posterior tip of the frontal, the supraoccipital,

epiotic, and pterotic. The dilatator operculi is well

developed, and inserts on the anterodorsal face of

the subopercle, posterodorsal interopercle, and the

opercle. Origin has greatly expanded to include

the dorsal faces of the prefrontal, frontal, supraoccipital, epiotic, and pterotic. The anterior fibers

cover the posterodorsomedial fibers of A 2P. The

hyomandibular is not included in the sites of origin. The levator arcus palatini is very small.

There is no section of the hyohyoidei abductores

to the fourth ray. The posteroventral bundle of

the semicircular portion of the hyohyoidei adductores attaches to the ventrolateral face of the fourth

radial. Two slips of fibers pass inward to the

medial face of the posterodorsal bundle. One passes

dorsomedially to attach to the posteromedial face

of epibranchial 3, the other passes posteroventrally

to fade out lateral to the pharyngoclavicularis internus. Both lie lateral to the posterior fibers of

levator externus IV.

There are no fibers from levator externus I to

epibranchial 2, and only a few from levator II to

the fascia between epibranchials 2 and 3. No other

fibers attach to epibranchial 3. Levator externus

IV is well developed. No lateral bundle of transversus dorsalis II was found, but it may be represented by a dorsomedial bundle which passes out

laterally to join the posterodorsal part of the

hyohyoidei adductores.

The hypochordal longitudinalis inserts on rays

D 2-4, while the transversus caudalis inserts on rays

V 2-3. The flexor ventralis externus inserts on the

bases of rays V 1-3, and its origin is expanded

distally onto the haemal spines.

Xenopterus naritus (Richardson)

FIGURE 158

The posteroventral portion of A IP is expanded

dorsally and originates from the roof of the orbit,

while the dorsal head of A 2a extends posteriorly

beyond the hyomandibular to the anterolateral

face of the pterotic. A 2P is as for Colomesus, except that the frontal secondarily roofs the dilatator

fossa, and some of the fibers arise from it. The

levator arcus palatini inserts on the hyomandibular

by a broad, flat aponeurosis.

The hyohyoidei adductores is poorly developed

in the outer wall of the opercular cavity, but with

the posterodorsal and posteroventral bundles still

well developed near their origins. The halves of

the sternohyoideus fuse in the anterior midline. A

well-developed and distinct intermandibularis is

present. It attaches in the fossa of the dentary below

the insertion of A 2, lying anterodorsal to the

angular.

Levatores externi II and III are fused, and levator internus II is not associated with transversus

dorsalis II medially. Adductor I is small. The

erectores dorsales and anales lie in a somewhat

more lateral position than do the depressores dorsales and anales. Inclinatores anales are attached to

the bases of the first and the twenty-first (twentieth

in the 124 mm specimen) to twenty-eighth fin rays.

The obliquus inferioris does not separate from

the obliquus superioris in the region of the anal

fin, and there is thus no anteroventral section

joining the fibers arising from the posteroventral

tip of the postcleithrum. The posterodorsomedial

bundle of fibers attaching to the haemal spine of

the twelfth vertebra is absent. The extreme anteroventral fibers of the obliquus inferioris attach to

the lateral face of the first branchiostegal ray. A

small aponeurosis from the obliquus superioris

attaches to the base of ray D 1. The hypochordal

longitudinalis and flexor ventralis externus are as

for Colomesus, and the transversus caudalis inserts

on the bases of rays V 1-2.

Arothron immaculatus (Bloch)

FIGURE 159

The posteroventral part of A IP is expanded

along the floor of the orbit, and A la covers A

2a laterally. A 2P is well developed, and A 3 is

much reduced (particularly dorsally). The anterior

part of the dilatator operculi inserts on the subopercle and opercle.

The posterodorsal bundle of the hyohyoidei adductores attaches to the anteroventral face of the

supracleithrum.
58

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

The fibers of levator externus I insert only on

epibranchial 1, and adductores II and V are absent.

The residual inclinator analis has fused with the

obliquus inferioris, and the first and last anal fin

rays have inclinators attaching to their bases.

The hypochordal longitudinalis is as for A.

honckenii. The single tendon of the transversus

caudalis attaches to the base of ray V 2. The flexor

ventralis attaches to the bases of rays V 1-5.

The posterodorsomedial bundle of the obliquus

inferioris fades into an aponeurotic sheet at the

level of the anal fin, the sheet attaching to the haemal arches of the thirteenth and fourteenth vertebrae.

Tetraodon schoutedeni Pellegrin

FIGURE 160

A 13 is well developed, and similar to that of

Xenopterus, the posteroventral portion having expanded posterodorsally along the roof of the orbit.

A 2a is reduced dorsally, and there is only a thin

slip of muscle to the posterodorsolateral face of the

hyomandibular beneath the dorsal process of the

opercle. The adductor operculi is very well developed. A lateral bundle of the sphincter oesophagi attaches to the anteroventral face of epibranchial 4.

The flexor ventralis externus inserts only on V 1,

while the flexor ventralis attaches to V 2-5. The

transversus caudalis inserts on V 2.

Summary of Tetraodontidae

A number of regions of the body in this family

show myological variation. The subdivisions of the

adductor mandibulae, while constant in presence

and position, show a considerable variation in relative development. This is particularly true of the

A 1 sections, and of A 20. The size and sites of

origin of the dilatator operculi differ markedly, as

does the insertion of the anterolateral bundle of

fibers of this muscle. The lateral fibers of the

hyohyoidei adductores vary in size and position.

The insertion of the levatores externi shows considerable variation, and there are other minor differences in the dorsal branchial musculature. The

number and form of the inclinatores anales differ,

and there is some variation in the relative development of the posterodorsolateral bundle of fibers of

the obliquus inferioris. The number of insertion

tendons (and their relative positions) of the hypochordal longitudinalis, flexor ventralis, flexor ventralis externus, and transversus caudalis varies

widely. The remaining muscles are relatively conservative in the members of the family examined.

Myological Descriptions of Representative Canthigasterids

The typical body outline of this monogeneric

family is illustrated in Figure 9. Fraser-Brunner

(1943) recognizes a single genus with 15 species in

this family. Representatives of two of the species

were dissected for this study.

The head region is higher, narrower, and of less

robust construction than in the tetraodontids.

Other bodily proportions are similar, and some inflation is possible. These fishes can also raise the

skin on the back into a ridge by contraction of the

underlying cutaneous musculature. They are

usually brightly colored coral reef forms, feeding

mainly on sea grasses and soft-bodied marine

invertebrates.

As outlined above, they are generally considered

to be closely allied to the Tetraodontidae.

Canthigaster margaritatus (Riippell)

FIGURES 161-167

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 161, 162: A 1 a,

A IP, A 2a, A 2P, A 3).—A la inserts on the

posteroventral face of the maxilla. The ventral

fibers arise from the posterodorsolateral preopercle.

The dorsal region overlies A 2a (with some fibers

arising from the fascia between them), and then

passes medial to that muscle to originate from the

dorsal metapterygoid. A IP originates from the

ethmoid and the ventral surface of the prefrontal.

A ventral extension of this muscle arises from the

lateral face of the parasphenoid anterior to the
NUMBER 155 59

orbit. The fibers insert on the posterodorsal face

of the maxilla, medial to A la. A 2a originates from

the lateral preopercle, metapterygoid, quadrate, and

hyomandibular. The muscle becomes tendinous anteriorly, and joins the lateral face of the tendon

of A 23. A 2P arises from the anterior faces of

the hyomandibular and prootic and the lateral

face of the posterior region of the parasphenoid.

The joint tendon with A 2a inserts on the medial

face of the dentary. A 3 originates from the lateral

faces of the quadrate, ectopterygoid, and metapterygoid, and inserts tendinously in the Meckelian

fossa.

LEVATOR ARCUS PALATINI (Figures 161, 162:

L.A.P. ).—A minute muscle, originating from the

ventral face of the postorbital process of the frontal

and inserting on the posterodorsolateral ridge of

the hyomandibular.

DILATATOR OPERCULI (Figure 161: D.O.).—Origin

is from the posterolateral frontal (primarily in

the gutter formed by the vertical lateral ridge of

this bone behind the orbit) and the anterior epiotic. The fibers insert on the posterodorsal face

of the interopercle, the anterior opercle, and the

dorsal process of the latter bone.

LEVATOR OPERCULI (Figure 161: L.O.).—Origin

is from the anterolateral face of the lateral process

of the pterotic, the fibers inserting on the posterodorsal face of the opercle.

ADDUCTOR ARCUS PALATINI (Figure 162: A.A.P.).—

The muscle originates from the lateral face of

the parasphenoid and passes laterally to insert on

the dorsomedial faces of the hyomandibular, metapterygoid, and ectopterygoid. Anteriorly, the fibers

cross the midline beneath the anterior part of the

parasphenoid and the vomer, attaching to the

medial faces of the palatines.

ADDUCTOR OPERCULI (Figure 163: AD.OP.).—The

muscle arises from the posteroventrolateral face

of the pterotic and inserts on the posterodorsomedial face of the opercle.

MUSCLES OF THE HYOID REGION

VALVULUS.—The muscle originates from the anteroventromedial face of the preopercle, and sweeps

forward in a dorsoventral curve to grade into the

tissues of the mandibular buccal valve. It lies

medial to the interopercle.

PROTRACTOR HYOIDEI (Figure 161: PR.HY.).—The

muscle is well developed, connecting the anterior

elements of the hyoid arch to the posteroventral

face of the dentary near the symphysis. The muscle is single anteriorly, and diverges into two halves

before attaching to the lateral faces of the anterohyal and ventral branchiostegal rays.

HYOHYOIDEI ABDUCTORES (Figure 161: H.AB.).—

The form of the muscle is very similar to that

described for Lagocephalus, with the following

differences. The large section to the first ray is

faintly subdivided into ventrolateral and dorsomedial bundles. A small bundle attaches to the

posteromedial face of basibranchial 1, just in front

of the section which fuses with its antimere in the

midline beneath hypobranchial 3.

HYOHYOIDEI ADDUCTORES (Figure 161: H.AD.).—

The form of this muscle is also very similar to

that described for Lagocephalus, but differs in the

following respects. The posterodorsal bundle

attaches to the anteroventral face of the supracleithrum. The posterior wall of the branchial (opercular) chamber is formed by fibers from the

posterolateral face of epibranchial 3, which pass out

laterally in front of epibranchial 4, and a ventral

bundle from the ventromedial face of the cleithrum.

STERNOHYOIDEUS (Figures 161, 163: STH.).—The

muscle is cone-shaped, with a fairly wide origin

on the anteroventral cleithrum and an aponeurotic

insertion on the ventrohyal. The halves fuse in

the anterior midline.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 163,

164: PHC.E.).—Origin is from the ventromedial

face of the cleithrum, the muscle dividing into

three bundles. The anterior one inserts on the

junction between basibranchial 2 and hypobranchial 2, the middle part inserts on basibranchial 3

and the posterior section attaches to the ventromedial face of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 163,

164: PHC.L).—The muscle arises from the anteroventromedial cleithrum. It passes anterodorsally

to insert on basibranchial 3 and ceratobranchial

5. In between the two points of insertion, the

fibers sweep across the midline to join their antimeres.
60

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

OBLIQUUS VENTRALIS HI (Figures 163, 164: OBL.

v.).—The fibers pass between the anteroventral

face of ceratobranchial 3 and the posteroventrolateral tip of the ventral process of hypobranchial 3.

TRANSVERSUS VENTRALIS v (Figure 164: TR.V.).—

This is a small muscle which crosses the ventral

midline between the anteroventromedial faces of

the fifth ceratobranchials. There is no transversus

IV, but it may have fused with the fibers of the

pharyngoclavicularis internus to form the transverse part.

RECTI VENTRALES I-IV (Figures 163, 164: RECT.

v.).—The first muscle consists of two parts. The

more medial section links the dorsomedial face

of the anterohyal with the anteroventral face of

hypobranchial 1. The lateral portion arises from

the dorsomedial surface of the anterohyal and

sweeps dorsally to attach to the anteroventrolateral

flange of ceratobranchial 1. Recti II and III interconnect the hypobranchials of the first and second,

and second and third arches, respectively. Rectus

IV passes from the anteroventral face of ceratobranchial 4 to the posteroventral tip of the ventral

process of hypobranchial 3.

RECTUS COMMUNIS (Figures 163, 164: R.COMM.).—

The muscle arises tendinously from the posterior

face of the ventrohyal. It passes ventral to basibranchial 1 (lying medial to the basibranchialhypobranchial ligament), where is develops a belly

of muscle fibers, before grading into a tendon

which attaches to the anteroventrolateral face of

ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI i-rv (Figure 163: L.EXT.).—

The muscles originate from the prootic and pterotic beneath the hyomandibular fossa. The first

muscle inserts on the dorsolateral face of epibranchial 1, while the second inserts on the dorsolateral

faces of epibranchials 2 and 3. There is no distinct

third levator. Levator IV is well developed, and

inserts along the entire dorsal surface of epibranchial 4. It continues posteriorly in the wall of

the opercular cavity, the fibers attaching to the

dorsomedial face of the clei thrum.

LEVATORES INTERNI II, HI (Figure 165: L.INT.).—

Levator II originates from the posteroventrolateral

face of the pterotic, and inserts on the anterodorsal

face of infrapharyngobranchial 2. Levator III arises

from the dorsolateral prootic and inserts on the

anterolateral face of infrapharyngobranchial 3 and

the dorsolateral edge of infrapharyngobranchial 2.

Levator II passes medial to levator III, and forms

an aponeurotic connection with transversus dorsalis

II.

OBLIQUUS DORSALIS IV (Figure 165: OBL.D.).—Origin is from the posterior and dorsal faces of epibranchial 4, the fibers passing anteromedially to insert

on the posterodorsal face of infrapharyngobranchial 2.

OBLIQUUS POSTERIOR.—The fibers of this muscle

are not well separated from the sphincter oesophagi, but pass from the dorsal tip of ceratobranchial 5 to the posteromedial face of epibranchial 4.

TRANSVERSI DORSALES II, iv (Figure 165: TR.D.).—

The anterior muscle arises from the midline and

attaches to the connective tissue covering infrapharyngobranchial 2 (there is no direct connection) and to the medial face of levator internus

II. Transversus IV crosses the dorsal midline directly beneath the posterior portion of transversus

II, connecting the medial faces of the fourth epibranchials.

RETRACTOR DORSALIS (Figure 165: D.RETR.).—The

muscle originates from the lateral face of the

exoccipital and the ventrolateral face of the

basioccipital. It inserts on the posterodorsal face

of infrapharyngobranchial 2.

ADDUCTORES I-V (Figures 163, 164, 165: AD.).—

The muscles pass between the anteromedial faces

of the ceratobranchials and epibranchials of the

first three arches, the medial faces of these bones

of the fourth arch, and from the dorsal tip of ceratobranchial 5 to the posterolateral face of ceratobranchial 4.

SPHINCTER OESOPHAGI (Figures 164, 165: s.o.).

Dorsally, the muscle consists of a bundle of fibers

across the midline, joined by a bundle from epibranchial 4. In addition, the muscle sends out a

bundle which attaches to the anterior face of ceratobranchial 4. Ventrally, there is a bundle across

the midline behind transversus IV. Immediately

above this, the fibers are transverse posteriorly, but

become increasingly longitudinally oriented anteriorly. This gives rise to a pair of fiber bundles

passing forward beneath the basibranchials to attach to the posteroventral face of basibranchial 1.

The anterior section of the pharyngoclavicularis

internus inserts between the halves.
NUMBER 155 61

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 161: ABD.S.).—

Origin is from the posterior face of the lateral

flange of the cleithrum, the muscle inserting on

the anterolateral bases of the principal fin rays.

ABDUCTOR PROFUNDUS.—The fibers arise from the

lateral face of the coracoid and the ventrolateral

cleithrum. Insertion is on the posterolateral bases

of the principal fin rays and on the posterolateral

face of the lateral half of the vestigial fin ray.

ARRECTOR VENTRALIS (Figure 161: ARR.V.).—This

is a small muscle, originating from the posterolateral face of the cleithrum beneath the lateral

flange. It inserts on the lateral extension of the

base of the medial half of the vestigial fin ray.

ADDUCTOR SUPERFICIAL^ (Figure 153 for Lagocephalus, ADD.S.).—Origin is from the dorsomedial

face of the cleithrum, the muscle inserting on the

dorsomedial bases of the ventral six rays, and the

dorsomedial faces of the next nine rays some distance distal to their bases.

ADDUCTOR PROFUNDUS (as above, but ADD.P.).—

The fibers arise from the medial faces of the cleithrum, coracoid, and scapula. Insertion is on the

ventromedial bases of the rays. There is no aponeurosis anteriorly on the body of the muscle as there

is in Lagocephalus.

ARRECTOR DORSALIS.—The muscle originates from

the cleithrum beneath the adductor profundus,

and inserts on the base of the medial half of the

vestigial fin ray.

CORACORADIALIS.—The muscle is better developed than in the tetraodontids examined. It passes

from the posterior process of the coracoid to the

distal ventral tip of the fourth radial.

PROTRACTOR PECTORALIS (Figures 161, 163:

p.p.).—Origin is from the posterolateral face of

the pterotic. The fibers fan out to insert broadly

on the dorsal face of the cleithrum and anteroventral supracleithrum.

LEVATOR PECTORALIS.—The muscle arises from

the pterotic behind the protractor pectoralis and

passes posteroventrally to insert on the dorsomedial

face of the cleithrum beneath the supracleithrum.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORSALES (Figure 166: INC.).—

There are two inclinators to the two posteriormost

fin rays, arising in the subdermal fascia and inserting on the posterolateral bases of the rays.

ERECTORES DORSALES (Figures 161, 166: EREC. ).—

The muscles originate from the lateral faces of

the pterygiophores and the neural spines of the

seventh to tenth vertebrae. They insert on the

anterolateral bases of the rays, partially overlying

the depressors anteriorly, and completely covering

them posteriorly.

DEPRESSORES DORSALES (Figures 161, 166: DEPR.).—

These muscles originate behind and medial to the

respective erectors, and insert on the posterolateral

bases of the fin rays.

SUPRACARINALIS ANTERIOR (Figures 161, 166: s.

ANT.).—Origin is from the supraoccipital and its

spine and the exoccipital. The lateral fibers pass

posteroventrally to attach to the dorsomedial faces

of the bifid neural spines of the first four vertebrae.

The dorsomedial fibers pass posteriorly to the anterolateral face of the first pterygiophore of the

dorsal fin.

SUPRACARINALIS POSTERIOR (Figures 166, 167: s.

POST.).—The fibers arise from the last pterygiophore of the dorsal fin and end on the anterodorsal

face of the neural spine of the penultimate vertebra. They attach to the tips of the neural spines of

the intervening vertebrae.

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES (Figures 161, 166: INC.).—

There are four of these muscles. The first residual

one arises in the fascia overlying the obliquus inferioris and attaches to the anteroventral tip of

the first anal pterygiophore. The first and last two

fin rays receive inclinators inserting on their lateral

bases, the fibers arising in the fascia over the ventral body muscles.

ERECTORES ANALES (Figure 166: EREC).—The

muscles originate from the anterolateral faces of

the anal pterygiophores, anterolateral to the origins

of the depressors, and insert on the anterolateral

bases of the fin rays.

DEPRESSORES ANALES (Figures 161, 166: DEPR.).—

The fibers arise posteromedial to those of the erectors, and insert on the posterolateral bases of the

rays.

INFRACARINALIS ANTERIOR.—The muscle is apparently represented by a bundle of fibers arising

from the ventral tip of the cleithrum, and passing
62

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

into the subdermal tissues as part of the longitudinal cutaneous.

INFRACARINALIS MEDIUS (Figures 161, 166: INF.

M.).—The muscle arises from the anteroventral

face of the first anal pterygiophore and grades posteriorly into the longitudinal cutaneous together

with the anteroventral bundle of the obliquus inferioris. Its posterodorsal surface gives rise to a

posterodorsomedial bundle of fibers attaching to

the anterior face of the haemal spine of the twelfth

vertebra. This bundle is probably derived from

the obliquus inferioris, which (in tetraodontids

and triodontids) gives rise to a similar bundle.

INFRACARINALIS POSTERIOR (Figures 166, 167: INF.

P.).—The fibers arise from the ventrolateral face

of the last anal pterygiophore, and insert on the

anteroventral face of the haemal spine of the penultimate vertebra. They contact the tips of the

haemal spines of the intervening vertebrae.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 167a: INT.).—The muscle

stretches between the fin rays, each ray receiving a

more or less distinct slip.

HYPOCHORDAL LONGITUDINALIS (Figure 167a:

H.L.).—The muscle originates from the lateral face

of the fused lower hypurals and inserts on the

bases of rays D 1—4.

FLEXOR DORSALIS (Figure 1676: F.D.).—The muscle is not well developed. It originates from the

lateral faces of the neural spines of the second

and third last vertebrae, the epural, and the anterodorsal tip of the urostyle, and inserts on the

anterolateral bases of rays D 1—3.

FLEXOR DORSALIS SUPERIOR (Figure 167: F.D.S.).—

Origin is from the lateral faces of the neural spines

and centra of the third to fifth last vertebrae. The

fibers sweep posterodorsally, grading into a tendon

inserting on the dorsolateral base of ray D 5.

FLEXOR VENTRALIS (Figure 1676: F.V.).—The

fibers arise from the lateral faces of the second

and third last vertebrae and the ural centrum.

The muscle inserts on the bases of rays V 1-5. The

section to ray V 5 is fairly well separated from

the other part, the two bundles being subequal

in size. The fibers to V 1, and some of those to

V 2 are partially separated from the main mass

of the muscle, lying on the medial side and passing posterodorsally instead of posteroventrally.

FLEXOR VENTRALIS EXTERNUS (Figure 1676:

F.V.E.).—The fibers arise from the lateral face of

the haemal spine of the penultimate vertebra, and

insert on the lateral bases of rays V 1-2.

FLEXOR VENTRALIS INFERIOR (Figure 167: F.V.I. ).—

Origin is from the lateral faces of the haemal spines

of the second to fourth last vertebrae, and the centra of the third and fourth last vertebrae. The muscle inserts on the anterolateral base of ray V 6.

TRANSVERSUS CAUDALIS (Figure 1676: TR.C).—

The fibers arise from the dorsolateral face of the

hypural plate, and insert on the anterodorsal faces

of rays V 1 and 2.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 161, 167a: EPAX.J.—The

fibers of this muscle attach variously to the rear

of the skull, the centra and neural spines, and

the dorsal caudal fin rays. In the posterior region,

the dorsal moiety becomes inclined at an increasingly oblique angle to the main section, and gives

rise to an aponeurotic sheet which, together with

a similar sheet from the obliquus inferioris, forms

a superficial aponeurosis to all the caudal fin rays.

The main medial portion inserts posteriorly on

the bases of rays D 2-5.

OBLIQUUS SUPERIORIS (Figures 161, 167a: OBL.S.).—

The muscle is small anteriorly, where it arises

from the posterodorsal tip of the cleithrum. It

broadens out posteriorly behind the abdominal

cavity, attaching to the centra and haemal spines

of the caudal vertebrae. Posteriorly, it inserts on

the bases of rays V 1-4.

OBLIQUUS INFERIORIS (Figures 161, 166, 167a:

OBL.L).—As in tetraodontids, the muscle has become

extensively subdivided. The main mass arises

anteriorly from the coracoid and ventrolateral

cleithrum. It passes posteriorly, the more dorsal

fibers attaching to the anteroventral faces of the

postcleithra, and then continuing posterodorsally

to fade aponeurotically into the fascia overlying

the midlateral septum. The anterodorsal fibers of

this section sweep up to attach to the posterolateral

base of the first pterygiophore of the dorsal fin.

The more ventral fibers pass beneath the tip of

the ventral postcleithrum, joining the fibers from

the posteroventral face of that bone to attach to

the anteroventral tip of the first anal pterygiophore.

The posterior section, which is somewhat separated
NUMBER 155 63

from the obliquus superioris, grades into an

aponeurotic sheet joining that of the dorsal moiety

of the epaxialis as described above. Anteroventrally,

this section passes beneath the posterior region

of the main anterior mass, and fades out in the

subdermal tissue covering the abdominal cavity,

where it contributes to the formation of the

longitudinal cutaneous. A small bundle passes

posteroventrally to join the dorsal surface of the

infracarinalis medius.

CUTANEOUS MUSCLES

The cutaneous muscular system is as for tetraodontids, the anterior longitudinal bundle of the

snout region overlying A IP and attaching to the

dorsal face of the palatine.

Canthigaster valentini (Bleeker)

FIGURE 168

The ventral portion of A 23 is expanded ventrally to almost completely cover A 3 laterally. The

obliquus posterior is well developed, with some

slight intermingling of fibers with adductor V at

its site of attachment to ceratobranchial 5. The

hypochordal longitudinalis inserts on rays D 2-4.

Myological Descriptions of Representative Diodontids

In his review, Fraser-Brunner (1943) recognized

three genera and about 18 species of diodontids

(see Figure 10 for body outline). Representatives

of two of these genera have been dissected. They

are much like the tetraodontids, but covered with

spines. The head is broad and flat, and their inflation capabilities often impressive. The jaws are

even better developed than in the two preceding

families, and the diet is primarily composed of

gastropods, hermit crabs, and echinoids. They occur mainly in coral reef and sandy bay environments, and swim almost exclusively by undulations

of the well-developed pectoral fins.

Diodontids are usually considered to be closely

related to tetraodontids, although they have occasionally been allied with the Molidae.

Diodon hystrix Linnaeus

FIGURES 169-175

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 169, 170: A la,

A IP, A 2a, A 23).—A 1 originates from the entire

lateral margin of the preopercle, the fascia over

the opercle-hyomandibular articulation, and the

posterodorsolateral edge of the hyomandibular.

The more posterior fibers pass anteriorly, while

the anteroventral fibers sweep anterodorsally to

insert on the ventromedial faces of the maxilla

and premaxilla. The anterolateral face of the muscle gives rise to a short tendon which passes into

the tissues of the lips at the corner of the mouth.

A 13 (Figure 170) is much reduced. It originates

from the posterodorsal palatine and the ethmoidvomer, and inserts by a sheetlike aponeurosis on

the posteromedial face of the maxilla (Winterbottom, 1971a). The remaining sections are greatly

modified, primarily through the enlargement of

A 2. The fibers of A 23 originate from the ventral

faces of the frontal and prefrontal, and the lateral

faces of the palatine, mesopterygoid, and parasphenoid (the latter three sites of origin being mainly

concerned with the posteroventral extension of the

muscle). In addition, the fibers meet their antimeres in the midline across the anteroventral region of the orbit. The posteroventral fibers are

continuous with the main mass of A 2 (which

probably represents A 2a), in which a great variety

of fiber direction is found. Fibers originate from

the lateral or anterior faces of the preopercle, hyomandibular, quadrate, mesopterygoid, pterotic,

sphenotic, frontal, pterosphenoid, prootic, and

parasphenoid. The ventromedial section is partially

subdivided anteriorly, and the medial portion may

represent A 3. Insertion is on the medial face of

the dentary. A <o is a small muscle from the anterior

face of the quadrate and ectopterygoid to the

Meckelian fossa.

LEVATOR ARCUS PALATINI (Figure 170: L.A.P.).—

This is a very small, half aponeurotic muscle,
64

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

which arises from the ventral tip of the lateral

flange of the sphenotic. It inserts on the medial

face of the posterodorsolateral ridge of the hyomandibular, passing between the fibers of both

A 2a and the dilatator operculi.

DILATATOR OPERCULI (Figure 169: D.O.).—A welldeveloped muscle, which originates from the dorsal

and ventral faces of the posterolateral flange of the

frontal, the lateral sphenotic, and the anterior and

posterior faces of the lateral flange of the pterotic.

Insertion is mainly on the anterior face of the dorsal

crista of the opercle, with a few fibers to the posterior margin of the crista.

LEVATOR OPERCULI (Figure 169: L.O.).—The

fibers arise from the dorsolateral margin of the

pterotic, and pass down to insert on the lateral

opercle, and the posterior face of the crista of that

bone.

ADDUCTOR ARCUS PALATINI.—A small muscle, extending from the lateral parasphenoid and prootic

to the dorsomedial faces of the palatine, mesopterygoid, metapterygoid, and hyomandibular. It does

not continue anteriorly across the midline.

ADDUCTOR OPERCULI (Figure 170: AD.OP.).—The

fibers arise from the ventral face of the pterotic

and insert along the posterodorsomedial rim of

the opercle.

MUSCLES OF THE HYOID REGION

VALVULUS.—The muscle arises from the posteromedial face of the dentary and the medial face

of the angular, and sweeps dorsomedially to fade

into the tissues of the mandibular buccal valve.

PROTRACTOR HYOIDEI. (Figure 169: PR.HY.).—

The fibers arise from the lateral faces of branchiostegal rays 2-6 and the lateral surfaces of the

anterohyal and posterohyal. The muscle inserts in

a groove along the posteroventral face of the dentary.

HYOHYOIDEI ABDUCTORES (Figure 169: H.AB.).—

The form of these muscles is very similar to that

found in tetraodontoids. The sections to rays 2 and

3 are well separated, and originate from the posterior face of the lateral crista of the first ray. The

section across the midline is poorly developed and

separated.

HYOHYOIDEI ADDUCTORES (Figures 169, 170, 171:

H.AD.).—The muscle is very well developed in the

lateral wall of the opercular cavity, fibers arising

from the anterodorsal face of the opercle, the posterolateral hyomandibular and the fascia beneath

the pterotic. Beneath the hyomandibular-opercle

articulation, a bundle of fibers arises from the inner

face of the lateral wall of the opercular cavity, and

passes posteriorly. It fades out on the cleithrura

ventral to the insertion of the protractor pectoralis.

Posteroventrally in the cavity, fibers arise from

the cleithrum, the fascia over the pharyngoclavicularis interims and ceratobranchial 4, and from the

fascia over the anterior region of adductor IV.

These bundles meet, pass laterally, and join the

posterodorsal region of the main mass of the muscle in the lateral wall of the cavity.

STERNOHYOIDEUS (Figure 171: STH. ).—The muscle originates from the anteroventral face of the

cleithrum and passes anteriorly to insert on the

posteroventral face of the ventrohyal. The two

halves fuse extensively in the midline. The posteromedial fibers pass dorsally, curving inward to

meet their antimeres, the posteroventromedial

fibers attaching to the cartilagenous knob between

the ventral tips of the cleithra.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 171,

172: PHC.E.).—Origin is from the ventromedial face

of the cleithrum, the fibers passing medial to the

pharyngoclavicularis internus and the rectus communis to insert on the anteroventral tip of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 171,

172: PHC.I.).—The fibers arise from the medial face

of the cleithrum and pass anterodorsally to insert

on the ventral faces of ceratobranchials 4 and 5,

with some connection to basibranchial 3.

OBLIQUI VENTRALES I-III (Figures 171, 172: OBL.

v.).—The first two muscles connect the hypobranchials and ceratobranchials of the first two arches.

Obliquus III passes between the posterior face of

the ventral process of hypobranchial 3 and the

anteroventral face of ceratobranchial 3.

TRANSVERSI VENTRALES IV, v (Figure 172: TR.V.).

The muscles connect the anteroventral faces of the

fourth and fifth ceratobranchials across the ventral

midline. The posterior muscle is well developed.

RECTI VENTRALES I-IV (Figures 171, 172: RECT.

v.).—The first muscle in this series passes from

the dorsal face of the anterohyal to the antero-
NUMBER 155 65

ventrolateral face of ceratobranchial 1. The next

three muscles arise from the anteroventral faces

of ceratobranchials 2-4, and attach to the posterior

faces of hypobranchials 1-3. The last of these muscles attaches to the posterior face of the ventral

process of hypobranchial 3.

RECTUS COMMUNIS (Figures 171, 172: R.COMM.).—

The fibers connect the posterior face of basibranchial 1 to the anteroventral face of ceratobranchial

5. The muscle is fibered throughout, and attaches

at both ends by short aponeuroses.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I, ii, iv (Figure 171: L.EXT.).—

The muscles originate from the ventrolateral prootic and pterotic, and from the ventromedial face

of the hyomandibular near its articulation with

the skull. They are well developed, and form a

sheet of fibers passing posteroventrally to insert

on the dorsal faces of epibranchials 1, 2, and 4.

Posterior to epibranchial 4 the muscle continues

as a thick sheet of fibers which attach to the dorsolateral face of the cleithrum.

LEVATORES INTERNI II, HI (Figure 173: L.INT.).—

Levator II originates from the lateral pterotic behind the hyomandibular fossa and passes anteroventrally, medial to levator III, to insert on the

dorsal rim of infrapharyngobranchial 2 and the

anterodorsal face of infrapharyngobranchial 3.

Levator III arises from the prootic and anteroventral face of the hyomandibular adjacent to the

fossa. The fibers course posteroventrally to the

dorsolateral face of infrapharyngobranchial 3.

OBLIQUUS DORSALIS HI (Figure 173: OBL.D.).—The

fibers connect the anterodorsal region of epibranchial 3 with the anterodorsal face of infrapharyngobranchial 3.

OBLIQUUS POSTERIOR (Figure 173: OBL.P.).—The

muscle is well developed, and connects the posteromedial face of epibranchial 4 with the dorsomedial

face of ceratobranchial 5.

TRANSVERSUS DORSALIS n-rv (Figure 173: TR.D.).—

Transversus II has undergone considerable modification. The anterior fibers pass forward to attach

to the dorsomedial face of infrapharyngobranchial

2. Behind them, a thinnish aponeurosis attaches

to the medial face of epibranchial 2. The fibers

join and sweep across the midline. Posterodorsally,

some fibers attach to the posterior faces of the

exoccipital and pterotic. Posterolaterally, the fibers

sweep outward and downward to attach to the

anteromedial face of the cleithrum. This section

lies medial to the hyohyoidei adductores and the

posterior part of levator externus IV. Transversus

III is a small muscle passing across the midline

between the dorsomedial faces of the third infrapharyngobranchials. Some of the anterior fibers

arise from the anteroventromedial faces of the

third epibranchials. Transversus IV connects the

anterodorsal faces of the fourth epibranchials across

the midline.

RETRACTOR DORSALIS (Figure 173: D.RETR.).—The

muscle is somewhat subdivided. Origin is from the

lateral faces of the centra and neural spines of the

fourth to sixth vertebrae. It inserts by a main

anterior bundle onto the anteromedial face of infrapharyngobranchial 3. Behind this, a large bundle dissipates in the tissues of the esophagus. A slip

of the more posterior fibers inserts on the anterodorsal wall of the swim bladder, in the region of

the constriction between the halves.

ADDUCTORES I-V (Figures 171, 172, 173: AD.).—

The first four muscles connect the anteromedial

faces of epibranchials 1-4 to their respective ceratobranchials. Adductor V arises from the ventrolateral face of ceratobranchial 5 and passes dorsally

to the posterolateral face of epibranchial 4.

SPHINCTER OESOPHAGI (Figures 172, 173: s.o.).—

The ventral section passes anteromedially between

the ventromedial faces of the fifth ceratobranchials.

The dorsal fibers of this part are more longitudinally oriented, and form an anterior bundle to

the ventral face of basibranchial 3. Dorsally, the

main mass of the muscle connects the ventromedial

faces of the fourth epibranchials, the ventral fibers

passing out as an aponeurotic sheet over the anterior face of adductor IV. A small bundle arises

from the main mass of the muscle behind ceratobranchial 5, and passes dorsomedially to attach

to the posteromedial face of epibranchial 4. Medially, the fibers sweep anteriorly in a small bundle

to attach to the posteromedial face of infrapharyngobranchial 3.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 169: ABD.S.)—

Origin is from the posterior and lateral faces of

the cleithrum beneath the ala laminaris externus.
66

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

A tendon inserts on the anterolateral base of each

of the principal fin rays. The ventral nine rays

possess anterodorsal flanges which overlap the base

of the preceding ray, and the tendons attach to

these flanges.

ABDUCTOR PROFUNDUS (Figure 169: ABD.P.).—The

muscle originates from the ventrolateral cleithrum,

the lateral coracoid, and the ventrolateral faces

of the ventral radials. Insertion is on the ventrolateral bases of the principal rays, there being

no section to the vestigial ray.

ARRECTOR VENTRALIS (Figure 169: ARR.V.).—The

muscle is fairly well developed, and originates from

the posterolateral face of the cleithrum, beneath

the ala laminaris externus. It inserts on the anterolateral base of the medial half of the vestigial fin

ray.

ADDUCTOR SUPERFICIALIS (Figure 174: ADD.S.).—

The muscle has the same form as that described

for tetraodontids. The ventral nine tendons insert

on the dorsomedial flanges of the respective rays,

the other slips inserting on the dorsomedial faces

of the rays distal to their bases.

ADDUCTOR PROFUNDUS (Figure 174: ADD.P.).—The

fibers arise from the medial faces of the coracoid

and cleithrum and insert on the ventromedial bases

of the principal rays.

ARRECTOR DORSALIS (Figure 174: ARR.D.).—The

muscle is poorly developed, arising from the medial

face of the cleithrum (lateral to the adductor

profundus), and inserts on the base of the medial

half of the vestigial fin ray.

CORACORADIALIS (Figure 174: COR.R).—The muscle connects the enlarged medial flange of the

fourth radial to the posteroventral flange of the

coracoid. It is joined by a bundle of the obliquus

inferioris which arises from the anteroventral face

of the ventral postcleithrum.

PROTRACTOR PECTORIALIS (Figures 169, 170, 171:

P.P.).—Origin is from the ventrolateral surface of

the winglike process of the pterotic. The fibers

pass posteroventrally to insert on the anterolateral

face of the dorsal region of the cleithrum.

LEVATOR PECTORALIS.—The muscle arises from

the posterior face of the lateral process of the pterotic and inserts on the anterodorsal tip of the

cleithrum.

MUSCLES OF THE DORSAL FIN

INCLINATORES DORSALES (Figure 169: INC.).—

There is a single inclinator arising from the fascia

overlying the dorsal extension of the obliquus inferioris. It inserts on the lateral face of the first

dorsal fin pterygiophore.

ERECTORES DORSALES (Figure 169: EREC. ).—Origin

is from the dorsal faces of the ventrolateral flanges

and centra of the tenth to fifteenth vertebrae, and,

posteriorly, from the ventrolateral faces of the

pterygiophores. The muscles insert on the anterolateral bases of the fin rays, and are partly overlain

by the depressors anteriorly, being completely covered by them posteriorly.

DEPRESSORES DORSALES (Figure 169: DEPR.).—The

sites of origin are much the same as for the erectors, but somewhat more lateral. The muscles insert on the posterolateral bases of the fin rays.

SUPRACARINALIS ANTERIOR.—The muscle has

partially fused with the epaxialis. It is contained

in the trough formed by the bifid neural spines

of the anterior vertebrae, and passes from the

supraoccipital to the first pterygiophore of the dorsal fin.

SUPRACARINALIS POSTERIOR (Figures 169, 1756: s.

POST.).—The muscle connects the last pterygiophore of the dorsal fin to the anterodorsal face

of the neural spine of the penultimate vertebra.

It lies between the tips of the neural spines of the

intervening vertebrae.

MUSCLES OF THE ANAL FIN

INCLINATORES ANALES (Figure 169: INC.).—There

are two of these muscles, both arising in the fascia

over the obliquus inferioris and inserting on the

ventrolateral face of the first anal pterygiophore.

ERECTORES ANALES (Figure 169: EREC).—Origin

is from the ventrolateral faces of the ventrolateral

processes of the tenth to fifteenth vertebrae. The

muscles insert on the anterolateral bases of the

fin rays.

DEPRESSORES ANALES (Figure 169: DEPR.).—Origin

is the same as for the erectors, the depressor of

each ray arising behind the respective erector. The

muscles insert on the posterolateral bases of the

rays, and arise lateral to the erectors.

INFRACARINALIS MEDIUS (Figure 169: INF.M.).

The fibers arise from the anteroventral face of the

first anal pterygiophore, and join with the ventrolateral section of the obliquus inferioris before

grading into the subdermal tissue as part of the
NUMBER 155 67

longitudinal cutaneous system.

INFRACARINALIS POSTERIOR (Figure 1756: INF.P.).—

This muscle connects the posterior face of the last

anal pterygiophore and the supporting haemal

spine to the anterior margin of the haemal spine

of the penultimate centrum.

MUSCLES OF THE CAUDAL FIN

INTERRADIALIS (Figure 175a: INT.).—The muscle

interconnects the caudal fin rays just distal to their

bases.

HYPOCHORDAL LONGITUDINALIS (Figure 1756:

H.L. ).—Origin is from the posteroventrolateral hypural plate, the dorsal face of the flange of the

ural centrum and the centrum itself, and the neural

and haemal spines and centrum of the penultimate

vertebra. The muscle inserts on the bases of rays

D 3-5.

FLEXOR DORSALIS (Figure 1756: F.D.).—Origin

is from the lateral face of the neural spine of the

penultimate vertebra, the muscle inserting on the

lateral bases of rays D 3-4.

FLEXOR DORSALIS SUPERIOR (Figure 175: F.D.S.).—

The fibers originate from the lateral faces of the

neural spines of the second to fourth last vertebrae, and the dorsolateral faces of the epural and

the hypural plate. The muscle inserts on the dorsolateral base of ray D 5.

FLEXOR VENTRALIS (Figure 1756: F.V.).—The

fibers arise from the ventral face of the flange of

the ural centrum, and the dorsolateral and ventromedial faces of the ventrolateral flanges of the second to fourth last vertebrae. Insertion is on the

lateral bases of rays V 2-4.

FLEXOR VENTRALIS EXTERNUS (Figure 1756:

F.V.E.).—The muscle arises primarily from the

fascia on the lateral surface of the flexor ventralis,

with some attachment to the lateral flange of the

ural centrum. It inserts on the lateral bases of rays

V 1 and 2.

FLEXOR VENTRALIS INFERIOR (Figure 175: F.V.L).—

Origin is from the ventrolateral faces of the third

and fourth last vertebrae, the muscle inserting on

the ventrolateral base of ray V 4.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 169, 170, 173, 175a: EPAX.).—

Anteriorly, the fibers arise mainly from the epiotic

and pterotic, and from the lateral faces of the bifid

neural spines of the anterior vertebrae (where the

fibers are poorly separated from those of the supracarinalis anterior). Posteriorly, the ventral moiety

inserts on the lateral bases of caudal fin rays D

1-5. The dorsal moiety is restricted to a section

arising from the dorsomedial faces of the bifid

neural spines of the fifteenth and sixteenth vertebrae. It joins the aponeurosis from the posterior

section of the obliquus inferioris to form an

aponeurotic sheet to all the caudal fin rays.

OBLIQUUS SUPERIORIS (Figures 169, 175a: OBL.S.).—

The fibers arise from the ventrolateral region of

the seventh vertebra, and increase in size posteriorly. The muscle inserts on the lateral bases

of the ventral caudal fin rays.

OBLIQUUS INFERIORIS (Figures 169, 174, 175a:

OBL.1.).—The muscle is considerably modified. The

anterodorsal section arises from the fascia over

the epaxialis and from the dorsolateral tips of the

first and last dorsal fin pterygiophores behind this.

Ventrally, a similar attachment occurs on the last

anal fin pterygiophore. The more dorsal of these

fibers pass to the posterodorsal face of the postcleithrum, the middle ones attach to the posteroventral face of the coracoid, while the ventral fibers

pass into the subdermal tissue, contributing to the

formation of the longitudinal cutaneous. The anteroventral face of the postcleithrum gives rise to

a short section which forms an aponeurosis with

the coracoradialis (Figure 174). A ventral section

passes posterodorsally, lateral to the erector-depressor complex of the anal fin, to attach to the

anteroventral surface of the ventrolateral process

of the sixteenth vertebra. This section fuses with

the infracarinalis medius anteriorly, and fades into

the subdermal tissue. The posteriormost section

arises from the ventrolateral process of the sixteenth vertebra, and soon grades into an aponeurosis which joins that of the dorsal moiety of the

epaxialis before inserting on the lateral bases of

the caudal fin rays.

SWIM BLADDER MUSCLES

In addition to the ventral fibers of the retractor dorsalis to the anterodorsal surface of the swim

bladder, the posterior border of the bladder is

covered by a muscle which passes dorsoventrally

across its surface (Figure 173: S.M.).
68

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

CUTANEOUS MUSCLES

The cutaneous muscles are much like those of

tetraodontids, although the transverse system is

not as well developed (particularly dorsally and

posteriorly). The longitudinal system is better developed than in the former group.

Chilomycterus orbicularis (Bloch)

FIGURE 176

The adductor mandibulae is not as well developed as in D. hystrix. There is no tendon from

the anterolateral face of A la to the lips. A 2a

does not extend beyond the border of the orbit,

and A 2P does not meet its antimere across the

midline at the front of the orbit. Since the posterior section of A 2 does not extend behind the

orbit, the fibers of the levator arcus palatini no

longer pass through the muscle.

The protractor hyoidei arises from branchiostegals 2 and 3, and possesses a distinct longitudinal

myocomma about the middle of its width. The

origin of the levatores externi is less from the posterodorsomedial face of the hyomandibular. Transversus dorsalis II is better developed, particularly

posterolaterally. The retractor dorsalis arises from

the lateral faces of the second to seventh vertebrae.

The ventralmost eight pectoral rays only possess

anterodorsal processes, with the concomitant change

in the insertion of the abductor superficialis. The

flexor dorsalis inserts on the bases of rays D 3-4,

and the flexor ventralis is subdivided near its

origin. The obliquus inferioris is much reduced,

being composed of only a few bundles of fibers.

In addition to the swim-bladder muscle mentioned in D. hystrix, there is a well-developed muscle from the anterodorsal surface of the bladder

which passes forward and ventrally around the

anterior end of the bladder as far as its anteroventral tip. The muscle is largely contained in the

groove separating the halves of the bladder.

Chilomycterus schoepfi (Walbaum)

FIGURE 177

A la is better developed dorsally than in D.

hystrix, and has acquired attachment to the head

of the hyomandibular and the anterolateral pterotic. This region of origin is somewhat aponeurotic,

and the fibers are inseparable from those of A 2a.

Insertion of the additional fibers is primarily on

the ventrolateral face of the maxilla. Anteroventrally, some of the fibers arise from the dentary

and articular. A IP is also better developed, as

is the A 2 complex.

The posterodorsal section of the hyohyoidei adductores has a tendon passing posteriorly over the

cleithrum to attach to the postcleithrum. The

pharyngoclavicularis internus is smaller, while the

externus division is larger than in D. hystrix. What

is apparently transversus ventralis IV is modified

to form an aponeurotic sheet to basibranchial 2,

i.e., it is obliquely oriented, and the fibers do

not meet their antimeres.

The levatores externi are as for C. orbicularis

and transversus dorsalis II is very well developed

posteriorly, with a large section attaching to the

dorsomedial cleithrum. Adductor III is small, and

the retractor dorsalis originates from the third

to seventh vertebrae. No inclinatores dorsales or

anales were separable. The anterodorsal origin of

the flexor dorsalis superior is more extensive. The

flexor dorsalis is also larger, with a thin aponeurosis to ray D 5. The flexor ventralis is not subdivided, and originates mainly from the medial

faces of the ventrolateral flanges of the second

and third last vertebrae.

The anteroventral section of the obliquus inferioris from the postcleithrum attaches to the

coracoid rather than joining the coracoradialis. The

section over the abdominal cavity is reduced, although not to the extent seen in C. orbicularis. The

posterodorsomedial section is bifid, attaching to

the lateral flanges of the thirteenth and fourteenth

vertebrae. The posteriormost section and the dorsal

moiety of the epaxialis are much reduced.

Summary of Diodontidae

The relative development of the A 1 and A 2

sections of the adductor mandibulae varies fairly

considerably, although the basic plan of the subdivisions remains constant. The sites of origin of

the levatores externi and the retractor dorsalis

vary, as does the relative development of the transversus dorsalis II. Other areas of the musculature

showing significant variation are the flexors of

the caudal fin and the development of the obliquus

inferioris.
NUMBER 155 69

Myological Descriptions of Representative Molids

The body outline of members of this family are

illustrated in Figure 11. Two out of the three

genera (possibly all monotypic) were dissected for

this study, no specimens of Masturus being available. The mouth is small, the dorsal and anal fins

very high, and rather stiff. The caudal peduncle

is aborted, so that the rays of the caudal fin lie

in an almost vertical line behind the dorsal and

anal fins, and appear to grade into them. The

pectoral fins are short. In swimming, the dorsal

and anal fins flap synchronously from side to side,

steering apparently being accomplished by using

the caudal fin as a rudder. The body is high and

thin, the shape being ellipsoid or circular. Molids

possess the powerful jaws typical of gymnodonts,

although their food is reported to consist of coelenterates and pelagic tunicates (Mola) or seaweeds

(Ranzania). They have a worldwide distribution

(Mola itself occurring in both tropical and coldtemperate waters). Molids are thought to be pelagic,

although the possibility that they are bathypelagic

cannot be ruled out.

Phylogenetically, they are usually considered to

be derived from the gymnodont line before separation of the tetraodontoid and diodontid stocks.

Mola mola Linnaeus

FIGURES 178-184

MUSCLES OF THE CHEEK

ADDUCTOR MANDIBULAE (Figures 178, 179: A la

A IP, A 2a, A 23, A 3).—A la is fairly small,

arising from the fascia over A 2 beneath the orbit,

and inserting on the posteroventral face of the

maxilla. A IP originates from the posterolateral

face of the palatine and the lateral parasphenoid.

It passes anteroventrally to insert on the posterodorsal face of the maxilla. A 2a originates from the

dorsolateral preopercle, the anterior and dorsal

hyomandibular and by a small slip from the ventromedial face of the pterotic. It passes anteriorly,

lateral to ramus mandibularis V, to insert with

A 23 and A 3 in the Meckelian fossa. A 2P originates from the lateral parasphenoid (some fibers

arising as far back as the posterolateral margin

of the bone beneath the basioccipital), the anteroventral and ventral prootic, and the dorsomedial

faces of the hyomandibular and metapterygoid. It

lies medial to ramus mandibularis V, and inserts

together with A 2a and A 3 in the Meckelian fossa.

A 3 arises from the lateral quadrate, symplectic,

mesopterygoid, and hyomandibular and passes forward to join the insertion tendon of the A 2 complex.

LEVATOR ARCUS PALATINI (Figure 178: L.A.P.).—

This is a small muscle, originating from the ventral face of the sphenotic at the rear of the orbit

and passing down to insert on the dorsal face of

the hyomandibular medial to the posterior extension of A 2a.

DILATATOR OPERCULI (Figure 178: D.O.).—Origin

is from the ventral face of the lateral process of

the sphenotic. The fibers insert aponeurotically

on the dorsal margin of the opercle.

LEVATOR OPERCULI (Figure 178: L.O.).—This is

a well-developed muscle, originating from the ventrolateral face of the pterotic and inserting on the

posterodorsal face of the opercle.

ADDUCTOR ARCUS PALATINI (Figure 179: A.A.P.).—

The muscle is well developed, and passes ventrolaterally from its origin on the lateral face of the

parasphenoid to insert on the dorsomedial faces

of the palatine, mesopterygoid, metapterygoid, and

hyomandibular. Posteriorly, the origin is aponeurotic. Anteriorly, a very small bundle of fibers

passes anterolaterally from the parasphenoid to the

palatine. It possesses a ventral aponeurosis, and R.

maxillaris V passes through it. It bears a striking

resemblance to the retractor arcus palatini of the

balistoids and ostracioids.

ADDUCTOR OPERCULI (Figure 180: AD.OP.).—The

fibers arise from the ventral face of the pterotic

and insert on the posterodorsomedial face of the

opercle.

MUSCLES OF THE HYOID REGION

VALVULUS.—Origin is from the ventromedial

face of the angular, the fibers sweeping anterodorsomedially to fade into the tissues of the mandibular buccal valve.

PROTRACTOR HYOIDEI (Figure 178: PR.HY.).—The

fibers arise from the posteroventral face of the

dentary and attach to the lateral faces of the an-
70

SMITHSONIAN CONTRIBUTIONS TO ZOOLOCY

terohyal and posterohyal. The more posteroventral fibers pass medially to a midventral raphe.

HYOHYOIDEI ABDUCTORES (Figure 178: H.AB.).—

There are three of these muscles. The dorsalmost

passes from the anterodorsomedial face of ray 2

to the posteroventromedial face of ray 3, the second has the same sites of attachment, but involving

rays 1 and 2, while the third muscle connects the

ventromedial face of ray 1 with the ventromedial

regions of the anterohyal and ventrohyal. The

muscles are well developed.

HYOHYOIDEI ADDUCTORES (Figures 178, 180:

H.AD.).—The muscle is well developed in the lateral

wall of the opercular cavity, where it attaches to

the medial faces of branchiostegal rays 2-6. A small

anterior slip passes ventrally to attach to the dorsal face of ray 1. Some of the dorsal fibers arise

from the medial face of the preopercle and the

anterodorsal face of the cleithrum. Ventrally, the

fibers attach to the anteromedial face of the cleithrum and the aponeurotic fascia covering the

pharyngoclaviculares. Posterodorsally, fibers of the

muscle arise from the medial face of the hyomandibular, ventral pterotic, and the fascia covering

the wall of the opercular cavity, which, in molids,

extends dorsally to the region of the sixth to seventh vertebrae (medial to the posterior part of

the pterotic and the supracleithrum). These fibers

form the dorsal and medial walls of the cavity between the pterotic and the fifth vertebra, ultimately fading out in the aponeurotic sheet which

attaches to the dorsomedial margin of the cleithrum.

HYOHYOIDEUS INFERIORIS (Figure 178: HY.IN.).—

This muscle is well developed, passing dorsolaterally from the midline to the lateral face of the

anterohyal and the base of the first branchiostegal

ray.

STERNOHYOIDEUS (Figures 178, 180: STH.).—Origin is from the anteroventral face of the cleithrum.

The ventral fibers pass medial to the rectus communis to the posterior face of the ventrohyal,

while the dorsolateral fibers lie lateral to this muscle, also attaching to the ventrohyal.

VENTRAL BRANCHIAL MUSCLES

PHARYNGOCLAVICULARIS EXTERNUS (Figures 178,

180, 181: PHC.E.).—The muscle is well developed

near its origin from the ventromedial face of

the cleithrum, but fades into an aponeurotic sheet

on the inner wall of the opercular cavity, just lateral to the heart. A small ventral bundle continues

anterodorsally to insert on the anteroventral face

of ceratobranchial 5.

PHARYNGOCLAVICULARIS INTERNUS (Figures 180,

181: PHC.I.).—A large bundle of the muscle inserts on the posteroventral margin of ceratobranchial 5. Most of the fibers grade into the fascia

formed by the pharyngoclavicularis externus and

the hyohyoidei adductores. A small dorsal bundle

continues posteriorly to attach to the medial face

of the cleithrum.

OBLIQUI VENTRALES I-III (Figure 181: OBL.V.).—

The muscles span the articulations between the

ventral faces of the ceratobranchials and the respective hypobranchials of the first three arches.

TRANSVERSI VENTRALES IV, v (Figure 181: TR.V.).—

The anterior muscle crosses the midline between

the anteroventromedial faces of the fourth ceratobranchials. Transversus V spans the midline between the anteroventromedial faces of the fifth

ceratobranchials, and is somewhat larger.

RECTUS VENTRALIS i (Figures 180, 181: RECT.V.).—

The muscle connects the anterolateral faces of the

first ceratobranchial and hypobranchial to the posterodorsal face of the dorsohyal.

RECTUS COMMUNIS (Figures 180, 181: R.COMM.).—

The fibers arise aponeurotically from the posteroventromedial face of the ventrohyal. They grade

into a thin, aponeurotic sheet which inserts on

the anteroventral face of ceratobranchial 5.

DORSAL BRANCHIAL MUSCLES

LEVATORES EXTERNI I, HI, iv (Figure 180: L.EXT.).—

Origin is from the dorsomedial face of the hyomandibular, and the muscles are small. Levator I

inserts on the dorsolateral face of epibranchial 1

and the ligament between the first and second

ceratobranchials. Levator III inserts on the dorsolateral faces of epibranchials 2 and 3, with the

bulk of the fibers serving the latter bone. Levator

IV is best developed, and inserts along the dorsomedial face of epibranchial 4.

LEVATORES INTERNI II, HI (Figure 180: L.INT.).

Both muscles originate from the posteroventral

face of the prootic and pass anteroventrally. Levator II inserts on the lateral face of infrapharyngobranchial 2, while levator III inserts on the
NUMBER 155 71

dorsolateral faces of infrapharyngobranchials 2 and

3.

OBLIQUUS DORSALIS HI (Figure 182: OBL.D.).—

The muscle connects the posterodorsal face of

epibranchial 3 with the posterodorsal faces of

infrapharyngobranchials 2 and 3.

TRANSVERSI DORSALES II, iv (Figures 180, 182:

TR.D.).—Transversus II arises from the midline

beneath and including the ventrolateral surface

of the parasphenoid. The more anterior fibers have

migrated forward along the parasphenoid, so that

this part of the muscle passes posterolaterally from

its origin. Insertion is on the dorsomedial face of

infrapharyngobranchial 2. Transversus IV passes

across the midline between the medial faces of

the fourth epibranchials.

RETRACTOR DORSALIS (Figure 182: D.RETR.).—

Origin is from the posterodorsolateral faces of the

exoccipital and basioccipital, and the neural spine

of the first vertebra. The muscle inserts on the

posterodorsomedial faces of infrapharyngobranchials 2-4.

ADDUCTORES IV, v (Figures 180, 182: AD.).—Adductor IV is well developed and connects the

medial and posteromedial faces of epibranchial

4 and ceratobranchial 4. Adductor V is small, passing from the anterodorsal tip of ceratobranchial

5 to the posterolateral face of epibranchial 4.

SPHINCTER OESOPHAGI (Figures 180, 181, 182:

s.o.).—The muscle surrounds the esophagus, attaching primarily to the posterior faces of epibranchial 4 and ceratobranchial 5. Dorsally, some

fibers become longitudinally oriented, lying both

lateral and medial to the retractor dorsalis. They

attach to the posteromedial faces of epibranchial

4 and infrapharyngobranchial 3. Ventrally, some

fibers also take on a longitudinal orientation, lying

dorsal to transversus ventralis V and attaching to

the anteromedial face of ceratobranchial 5.

MUSCLES OF THE PECTORAL REGION

ABDUCTOR SUPERFICIALIS (Figure 178: ABD.S.).—

The fibers arise from the anterolateral face of

the cleithrum and insert on the dorsolateral faces

of the principal fin rays.

ABDUCTOR PROFUNDUS (Figure 178: ABD.P.).—

Origin is from the lateral faces of the cleithrum

and coracoid, the muscle inserting on the posterolateral faces of the principal rays and the lateral

base of the vestigial ray.

ARRECTOR VENTRALIS (Figure 178: ARR.V.).—The

muscle arises from the lateral cleithrum dorsal to

the abductor superficialis, and inserts on the anterodorsal face of the medial half of the vestigial

fin ray.

ADDUCTOR SUPERFICIALIS (Figure 183: ADD.S.).—

The fibers arise from the anterodorsomedial face

of the cleithrum, and insert on the anteromedial

faces of the principal rays some distance distal to

their bases.

ADDUCTOR PROFUNDUS (Figure 183: ADD.P.).—

Origin is from the medial faces of the cleithrum

and coracoid and the posterolateral face of the

latter bone. The muscle inserts on the posteromedial faces of the principal rays a little distal

to their bases.

ARRECTOR DORSALIS (Figure 183: ARR.D. ).—This

is a small muscle, originating from the medial

face of the cleithrum and inserting on the medial

face of the medial half of the vestigial fin ray.

PROTRACTOR PECTORALIS (Figures 178, 180: P.P.).—

The muscle originates from the posterodorsal tip

of the hyomandibular and the pterotic behind it.

It attaches to the anterodorsal face of the cleithrum. The medial fibers intermingle somewhat

with the lateral fibers of the levator pectoralis.

The muscle lies lateral to the adductor operculi

but medial to the levator operculi.

LEVATOR PECTORALIS (Figure 180: TR.).—The

fibers of this muscle pass medial to the adductor

operculi, and arise from the fascia of the opercular

cavity beneath the posterior extension of the hyomandibular. The fibers insert on the anterodorsomedial face of the cleithrum.

MUSCLES OF THE DORSAL FIN

ERECTORES AND DEPRESSORES DORSALES (Figures

178, 184: EREC. + DEPR.).—Only the erectors and

depressors of the first two fin rays have separate

tendons. In the next fourteen rays, the erectors

and depressors have fused, and insert by a single

tendon along the lateral face of each ray a little

distal to the base. Origin is from the lateral faces

of the vertebral centra and neural spines, the posterodorsal surface of the skull, and the septum in

the midline dividing the dorsal and anal fin musculature. The ventral fibers are continuous with

the surrounding fibers, particularly anteriorly. The
72

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

muscles to the more anterior rays tend to lie nearer

the midline, those to middle rays being best developed. The lateral fibers of the more anterior

muscles also take origin from the medial face of

the thick, subdermal fascia (represented as cut surface in Figure 178, but not in Figure 184).

SUPRACARINALIS ANTERIOR.—This is a small muscle which arises from the posterodorsal face of the

supraoccipital. The fibers soon grade into a long,

thin tendon which attaches to the anterodorsal

face of the first dorsal pterygiophore.

MUSCLES OF THE ANAL FIN

ERECTORES AND DEPRESSORES AN ALES. (Figure 184:

EREC. + DEPR.).—The first two fin rays have separate erector and depressor tendons, the tendons

to the other fourteen fin rays being compound,

owing to the fusion of the erector and depressor

muscles. Insertion of these tendons is on the lateral

faces of the rays a little distal to their bases. The

fibers originate from the lateral septum, the centra

and haemal spines of the seventh to sixteenth vertebrae, and the basal pterygiophores of the anal fin.

The fibers do not encroach on the abdominal

cavity, and intermingle in the dorsal region.

LATERAL BODY MUSCLES

EPAXIALIS (Figures 178, 184: EPAX.).—The muscle

is much reduced. Anteriorly, it arises from the posterodorsal tip of the epiotic. It passes posteriorly

as a very thin sheet, just below the skin, and

gradually becomes broader. It is separated from

the erector-depressor complex by a tough fascia,

from the medial surface of which the lateral fibers

of this latter complex arise. Vague myomeres are

recognizable, there being some fifteen of them before the fibers become continuous with the section

serving the dorsal eight caudal fin rays. This main

posterior section arises from the lateral faces of

the caudal fin supporting elements and the centra

and neural spines of the fourteenth to sixteenth

vertebrae. Insertion is tendinous on the anterolateral bases of the eight dorsal caudal fin rays.

OBLIQUUS SUPERIORIS (Figure 184: OBL.S.).—Posteriorly, vague fibers in the subdermal tissue are

continuous with the anterodorsolateral surface of

the muscle mass serving the ventral caudal fin rays.

The mass of this musculature arises from the

lateral faces of the ventral caudal fin supporting

elements and the centra and haemal spines of the

fifteenth and sixteenth vertebrae. Insertion is

tendinous on the anterolateral bases of the eight

ventral caudal fin rays.

OBLIQUUS INFERIORIS (Figure 178: OBL.I.).—The

muscle is reduced to two small fiber bundles. The

anteroventral one arises from the posteromedial

face of the coracoid, and sodn fades out in the

fascia overlying the abdominal cavity. The other

section arises from the posteroventral tip of the

postcleithrum and passes posteroventrally into the

subdermal tissue, fading out just above the first

pterygiophore of the anal fin. It is just possible

that this section represents the residual first in

clinator analis, but it seems more likely that it

is part of the obliquus inferioris.

Ranzania laevis (Pennant)

FIGURE 185

A la is smaller, while A 13 originates predominantly from the ventrolateral prefrontal and

frontal. A 2a is smaller, without a posterior section along the hyomandibular to the pterotic. A

2P does not reach the rear of the orbit, nor does

it extend far in front of it. A 3 appears to be

absent. The levator arcus palatini is better developed. The levator operculi originates more from

the supracleithrum than from the pterotic. There

is no small, anterior bundle of the adductor arcus

palatini.

The valvulus arises from the anterodorsal face

of the interopercle. Only a small bundle of the

hyohyoidei adductores is developed in the dorsolateral wall of the opercular cavity above the sixth

branchiostegal ray. Rectus ventralis II joins ceratobranchial 2 to hypobranchial 1 and basibranchial

I. Both sections of the pharyngoclaviculares are

more diffuse.

There are four levatores externi. Transversus

dorsalis II is more complex, since some of the

posterolateral fibers attach to the anteromedial

face of epibranchial 3. Obliquus dorsalis II passes

from the dorsal face of epibranchial 2 to the dorsolateral region of infrapharyngobranchial 2. This

may represent that portion of transversus dorsalis

II which usually arises from the epibranchial, and
NUMBER 155 78

which has in this case become separated by the

dorsal expansion of infrapharyngobranchial 2. The

protractor pectoralis grades into a diffuse aponeurosis attaching to the posterodorsal face of the

preopercle, and passing lateral to the levator operculi.

The first dorsal fin ray only has both an erector and a depressor. The broad tendons of the

rest of the compound muscles overlap onto the

base of the preceding ray. The last three tendons

pass anterior to the bases of the last three rays,

and meet their antimeres in the midline just above

the platelike, cartilagenous pterygiophores. No

fibers arise from the subdermal fascia.

The muscles to the anal fin rays are as described

above for the dorsal fin. Their origin is more extensive, and includes the posteromedial face of the

cleithrum. The fibers virtually cover the abdominal cavity ventrally. The residual inclinator analis

arises from the anterolateral base of the first anal

pterygiophore, but fades out in the subdermal tissue before reaching the posteroventral tip of the

postcleithrum. There are no fibers from the postcleithrum.

The epaxialis is restricted to a well-defined muscle serving the dorsal ten caudal fin rays, with no

fibers from the subdermal tissue. The obliquus

superioris is likewise well separated from the

erector-depressor complex of the anal fin, and

inserts on the bases of the ten ventral caudal fin

rays. The obliquus inferioris is thus confined to

a small bundle of fibers from the posteroventral

face of the coracoid which fades out in the fascia

over the abdominal cavity.

Phylogenetic Significance of Observed Myological Variation

Each muscle is analyzed on the assumption that

nothing is known of the phylogeny of the contained units. This approach has certain drawbacks.

It precludes, for example, the possibility of any

explanation based on parallel or "convergent"

evolution, although the former phenomenon is

often traceable through the presence of reductive

trends. Evidence from muscles which suggest phylogenies other than the one postulated in Figure

44 (which is derived from the evidence of 64 percent of the muscles for which phylogenetic interpretation proved possible) is reinterpreted immediately

after the initial analysis of the muscle concerned,

and I have attempted to provide plausible explanations for the discrepancies. In this connection, it

is of interest to note that the phytogenies initially

indicated by these muscles seldom agreed with each

other, which is a further justification for their

reinterpretation.

It should be stressed that in this interpretive

section, all statements concerning phylogeny and

character state are based on a consideration of the

muscle being reviewed at that time only, and are

not intended as generalized or particularized statements of fact outside that context. It should also

be noted that one of the major difficulties in deciding character state in fish muscles is due to the

lack of reliable, published information on the

majority of fish groups.

In the following section, the letters "R.T." indicate that there is some reason to believe that the

phylogeny indicated by that muscle may be the

result of a reductive trend. The term "R.T. pars"

means that only some of the phyletic lines exhibit

a reductive trend in the character under consideration. These abbreviations are used whether the

indicated phylogeny agrees or disagrees with that

postulated in Figure 44. The Hennigian nomenclature to denote character state is used, which

roughly corresponds to more widely used terms as

follows: apomorph (specialized, derived); autapomorph (specialized in one lineage only—denoted

by "A" in Figure 44); plesiomorph (primitive,

generalized); symplesiomorph (shared primitive)

and synapomorph (shared specialized). The

nuances of the Hennigian nomenclature differ

slightly from the alternative terms given above—

plesiomorph meaning "primitive" for the group

under consideration only, and always defined relative to apomorph.

Symbols used in the phylogenetic tree accompanying each muscle (Figures 12—43) are in the

"List of Abbreviations." In interpreting the phylogenetic trees accompanying the muscle analyses,

the following conventions are used: oblong "boxes"

indicate a common ancestor for all the families

whose lines arise from the "box" itself; lines which

branch are to be interpreted as is usual for phylo-
74

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

genetic trees, i.e., they indicate the sequence of

branching in relative time; "boxes" with one end

open connect up with the similar "box" with the

opposite end open, and indicate a common ancestor for the families arising from both parts

(they only appear when the analysis of the muscle

indicates a sequence of branching differing from

the one postulated in Figure 44).

Interpretation

1. ADDUCTOR MANDIBULAE, SECTION A 1 (Figure

12).—It is probable that the ancestral tetraodontiform condition of this section was such as is found

in most perciforms with protrusile jaws—i.e., the

section is not subdivided, and inserts high on the

posterodorsal face of the maxilla (the anteroventral region being ligamentously continuous with

A 2). As such, it is found in all the Triacanthodidae

examined except the two long-snouted genera

(Macrorhamphosodes and Halimochirurgus), where

the protrusibility of the jaw has been lost with the

elongation of the snout.

In triacanthids, the section is more intimately

associated with A 2, the tendon to the maxilla

lying in an almost horizontal plane, and being

much reduced. This is presumably associated with

a lesser degree of jaw protrusion and the more

incisiform teeth, perhaps indicating that biting

and nibbling are important in feeding. The only

other family in which A 1 is single is the triodontids, where the muscle inserts broadly on the interdigitated elements of the upper jaw.

There is a fairly clear dichotomy between the

other families. In balistoids and ostracioids, a deep

subdivision to A 1 develops (A IP), lying, for

the most part, medial to A 2. In monacanthids,

considerable further subdivision of both sections

has occurred, but not in balistids. Ostracioids have

lost A la, and A 13 develops three heads of origin.

It seems likely that the common balistoid-ostracioid

ancestor possessed a condition similar to that found

in the extant Balistidae. The subdivisions presumably allow more controlled nibbling movements of the upper jaw. It is therefore not

surprising to find their greatest development in

the more herbivorously inclined monacanthids than

in the other more omnivorous groups.

In the gymnodonts (exclusive of triodontids),

there are again two subdivisions of A 1. A lo

(which appears to be homologous with the balistoid A la) is very well developed in all families

except the molids. It reaches the height of its development in the diodontids. A IP (which does

not seem to be homologous with that of balistoids

+ ostracioids) is a dorsal subdivision of A 1, and,

in most cases, acquires attachment to the prefrontal region of the skull. It is well developed

in molids, and enormously enlarged in the tetraodontoids, where it extends posteriorly along the

parasphenoid beneath the orbit. It is small in

diodontids, where most of the area of its origin in

the other families has been 'taken over' by A 23.

The small size is probably associated with the

lateral migration of the oblique eye muscles (see

Winterbottom, 1971a). In these gymnodonts, the

feeding emphasis is on grinding and crushing—

hence the massive jaws and well-developed musculature.

Phylogenetically, the form of A 1 in the triacanthodids is assumed to be plesiomorph. Triacanthids are autapomorphly specialized, while all the

other families are linked by the broad insertion

of A 1 g on the maxilla. Triodontids possess a

condition similar to what one would expect

in the common ancestor of these families. The

balistoids and ostracioids are linked by the

development of the deep A IP subdivision (see

analysis above), and it appears that the balistoids

form the plesiomorph sister group of the ostracioids

(where A la is lost). The molids appear to form

the plesiomorph sister group of the diodontids and

tetraodontoids, in which latter A la is well developed and attaches to the preopercle laterally. Diodontids do not have the well-developed A IP of

the tetraodontids and canthigasterids, but this is

probably an autapomorph condition. However,

the enlargement of this subdivision (relative to

the condition in both diodontids and molids) in

the tetraodontoids does seem to be synapomorph,

and thus valid as phylogenetic evidence.

2. ADDUCTOR MANDIBULAE, SECTION A 2 (Figure

13).—A 2 consists of two subdivisions in all the

families except the triacanthids and the two longsnouted genera of the triacanthodids (Macrorhamphosodes and Halimochirurgus). In the more

generalized tetraodontiforms, A 2a lies dorsolaterally and A 23 lies ventromedially. The subdivisions are separated by the? path of ramus

mandibularis V, which passes medial to A 2a and
NUMBER 155 75

lateral to A 2P (except in the ostracioid families

where it lies medial to both sections, and may

indicate the sister group status of the two families).

It is by no means certain whether the ancestral

condition of this muscle in the pretetraodontiforms

was divided or undivided, and the usefulness of

it as a phylogenetic indicator among the more

basal groups is thus negligible. The generalized

condition of section A 2 as described above is

found in the triacanthodids, triodontids, balistoids,

and ostracioids. The condition in triacanthids

appears to be autapomorph. Balistoids are linked

by the development of a ventral section, A 2o, although this may be absent in certain specialized

monacanthid genera. The synapomorphic condition of A 2 unites the gymnodonts (except the

triodontids). Here A 23 has expanded dorsally

and medially, above A 3, to include the parasphenoid and prootic in its sites of origin. The

molids show a lesser (and thus plesiomorph)

development of the section anteriorly than is

found in the remaining families. Out of these

last three families, only the diodontids show an

enormous, anterodorsal development of the section to the ventral roof of the orbit, but this is

an autapomorph condition.

In functional terms, it seems that the much

broader anterior portion of the diodontid cranium

is an adaptation to the inequality in the jaw

musculature. The muscles to the upper jaw are

much weaker, and those to the lower jaw much

more powerful than in the tetraodontoids. Thus,

there will be greater force tending to push the

upper jaw dorsally on the contraction of the jaw

musculature, this force being in some measure balanced in tetraodontoids by the almost equal force

applied to the upper jaw. Hence, a stronger bracing of the elements of the upper jaw against the

skull is required in diodontids, and is reflected in

the broader anterior region. The same argument

may apply in reverse to the canthigasterids, whose

jaw musculature is relatively weaker than that of

the tetraodontids and diodontids. Here the snout

region is relatively more elongate than in the other

two families.

3. ADDUCTOR MANDIBULAE, SECTION A 3 (Figure

Ha).—The section is of little use in phylogenetic

interpretations. It is almost uniformly present in

all the families (absent in three genera of triacanthodids), but is not always completely separated

from the overlying sections of A 2. In the ostracioids, however, the dorsal fibers are continuous

with the ventral region of A IP indicating that

the Aracanidae and Ostraciidae are sister groups.

4. ADDUCTOR MANDIBULAE, SECTION A to (Figure

14fr,c).—The section is possibly present in the

triacanthodid Hollardia (the fibers do not, however, reach the quadrate), and is fully formed in

triodontids, diodontids, and tetraodontids. In the

three latter families, the muscle originates from

the palatal arch (anterior face of quadrate and

ectopterygoid in the diodontids and tetraodontids,

and the medial face of the quadrate and metapterygoid in triodontids). Since it seems likely that the

triodontid condition is autapomorph, we can say

nothing further concerning the phylogeny of these

three families.

The simplest inference is that the section developed soon after the gymnodont line diverged, and

was correlated with the powerful, crushing "beak"

of these fishes. Its absence in canthigasterids and

molids ties in very nicely with their diet (canthigasterids are mainly herbivorous, or take softbodied marine invertebrates—molids apparently

feed largely on medusoid coelenterates and salps),

where powerful jaws are not necessary. It is thus

feasible that the section has been lost separately

in the two lineages (Figure 14c).

5. LEVATOR ARCUS PALATINI (Figure 15a).—

Little can be deduced about the detailed familial

interrelationships from this muscle. It is relatively

well developed in triacanthoids, triodontids, and

molids. It is rather poorly developed in all the

other families (except a few ostraciids), but in

somewhat different ways. In balistoids and ostracioids, as a result of the ventral extension of the

sphenotic region immediately behind the orbit,

the area containing the muscle is reduced. This

may be correlated with the presence of the retractor arcus palatini (which appears to perform a

similar function anteriorly—see below). In diodontids and tetraodontoids, the hyomandibular extends posterodorsally far behind the orbit. Here

again the muscle is small, but this time its reduction is probably associated with the decreased importance of the palatal arch in respiration, and

the concomitant increase in the first branchiostegal

ray pumping mechanism.

6. DILATATOR OPERCULI (Figure 156).—In its

plesiomorph condition (as found in most perci-
76

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

forms), this muscle arises from the dorsolateral

surfaces of the sphenotic and pterotic, and inserts

tendinously on the tip of the dorsal process of

the opercle. As such, it is present in triacanthoids

and triodontids. In molids, it inserts on the anterodorsal rim of the much-reduced opercle. It is very

well developed in all the other families (it is

worth adding here that these are the groups in

which the levator operculi is small), but there

again appear to be two lines. In balistoids and

ostracioids, the origin is low on the skull, and

contained in the dilatator fossa (synapomorph),

which is particularly well covered laterally by the

sphenotic in ostracioids (also synapomorph). The

insertion has become specialized in balistoids, and

the fibers attach to the dorsolateral surface of the

opercle as well as the dorsal rim (the latter site

being of less importance in monacanthids). In

ostracioids, the muscle attaches to the remains of

the dorsal process of the opercle (the more so in

the aracanids), this apparently being the plesiomorph condition. The muscle becomes very well

developed (particularly in the dorsal region of

origin) in diodontids and tetraodontoids. The

fiontals are included among the sites of origin,

and insertion is all around the dorsal process of

the opercle. Tetraodontids and canthigasterids are

linked synapomorphly by the presence of an anterolateral strap of muscle fibers to the interopercle

(canthigasterids), preopercle (Lagocephalus), or

subopercle (most other tetraodontid genera). The

large development of the muscle in the latter three

families is again presumably associated with

changes in respiratory mechanism, and would allow for more forceful operation of the opercular

suction pump.

7. LEVATOR OPERCULI (Figure 16a).—Many

perciforms and the triacanthoids exhibit an apparently plesiomorph condition of this muscle.

It consists of anterior and posterior parts, the

former primarily arising from the pterotic, the

latter from the posttemporal. In all other tetraodontiforms, the muscle is single. In the balistoids

and ostracioids, it is small, and arises from the

secondary portion of the pectoral girdle (posttemporal and, in balistoids, the supracleithrum).

In the gymnodonts, however, the muscle is well

developed, and originates from the pterotic and

some of the bones dorsal to it. There are two possible interpretations. Either the former condition

represents the pars posterior of the muscle and

the gymnodont condition the pars anterior, or

else (and more likely) the muscle was reduced

to a single entity in a postulated common ancestor, this then developing in the directions outlined

above. The available evidence does not seem to

warrant a firm conclusion in this matter. The

gymnodont condition is presumably associated with

the increased use of the opercle and subopercle in

respiration. Both conditions are synapomorph relative to the triacanthoid state, and indicate a common ancestor for each of the two groups which is

not shared by the triacanthoid fishes.

8. ADDUCTOR ARCUS PALATINI (Figure 166).—

The plesiomorph condition, in which the muscle

occupies the floor of the orbit, is found in most

perciforms, triacanthodids, and triodontids. Triacanthids are somewhat specialized in that the

muscle has expanded anterodorsally in front of

the orbit. In balistoids, the muscle is largely in

front of the orbit, in ostracioids it is completely

so. In both, the anterodorsal fibers are to some

degree continuous with those of the retractor arcus

palatini. The muscle is also plesiomorph in molids.

Mola (but not Ranzania) develops a small, longitudinal, anterior bundle which inserts on the palatine and mesopterygoid. The homology of this

bundle is not clear (see below). In diodontids, the

muscle is small and confined to the orbit, while

the fibers continue anteriorly in tetraodontoids to

connect the medial faces of the palatines across

the midline beneath the vomer. Phylogenetic interpretation is difficult. The triacanthid condition

appears to foreshadow the development of the retractor arcus palatini. It is thus possible that (1)

the anterior bundle of Mola is a "de novo" development, (2) molids were derived from the ancestral stock before the separation of the triodontids,

the molid sister group (i.e., all other gymnodonts)

losing the anterior bundle (in which case we cannot explain the absence of the bundle in Ranzania),

or (3) the incipient retractor arcus palatini has

been lost in three separate lineages—triodontids,

Ranzania, and the diodontids plus tetraodontoids.

It seems that the acceptance of the "de novo"

development of the bundle in Mola is the most

parsimonious interpretation. However, the anterior

bundle can be of little functional significance

at this size, and its morphological similarity to

the retractor arcus palatini of balistoids and ostra-
NUMBER 155 77

cioids adds an element of incredulity to such an

acceptance. It seems better to leave this part of

the interpretation open to question (although

atavism may be involved). Tetraodontoids exhibit

a synapomorph condition in the anterior extension of the muscle across the dorsal midline, while

there is a partial (balistoids) or complete (ostracioids) migration of the muscle in front of the orbit.

Functional interpretations pose as much of a

problem as those of a phylogenetic nature. Presumably the triacanthid condition is a response

to the increased length of the snout, which is continued further in the balistoids and ostracioids.

However, it is not so easy to postulate a reason

for the difference between the tetraodontoid and

diodontid conditions, and none will be attempted.

9. RETRACTOR ARCUS PALATINI (Figure 17a).—

The muscle has only become distinct in the balistoids and ostracioids, although its development is

apparently foreshadowed by the dorsal extension

of the adductor arcus palatini in triacanthids (see

above). The muscle is well separated from the

adductor arcus palatini and inserts tendinously

on the dorsomedial face of the palatal arch in

ostracioids. The muscle is less well separated with

a more vertical fiber direction, and inserts on the

dorsolateral face of the palatal arch in the balistoids. The balistoid condition is not considered

to be wholly plesiomorph, since the muscle is very

well developed. In this respect, the ostracioids are

more plesiomorph; however, here the orientation

of the fibers, the tendinous insertion, and the complete separation of the muscle from the adductor

arcus palatini seem to be synapomorph. The condition in Mola has been discussed above, but the

absence of a well-developed muscle in gymnodonts

is scarcely suprising in view of the interdigitation

of the palatine with the ethmoid-vomer region of

the skull.

The development of this muscle is presumably

in response to the elongation of the ethmoid region.

Usually, the palatal arch is moved laterally by the

contraction of the levator arcus palatini. However,

the elongation of the ethmoid region decreases the

mechanical advantage of this muscle, since it is

situated at the rear of the orbit. The development

of the retractor arcus palatini may alleviate this

deficiency. The anterior fibers of the adductor arcus

palatini in certain chaetodontins and pomacanthins

show a somewhat similar orientation to those o£

triacanthids (although not so pronounced). In

acanthurids (including the Zanclinae) a welldeveloped retractor arcus palatini is present. The

homologies of this with the balistoid-ostracioid

muscle are uncertain. In balistids, the posterodorsal

force of the muscle causes the arch to rotate outward about its articulation with the palatine. In

monacanthids, the fibers are more vertical, and

rotation could occur about the cartilagenous ball

between the palatine, vomer, and ectopterygoid.

In ostracioids, the movement seems to take place

between the palatine and vomer.

10. ADDUCTOR OPERCULI (Figure 176).—The

muscle is present in all the families examined. It

originates from the pterotic, prootic, or both in

all except the ostracioids, where the fibers arise

from the occipital region. This condition is apomorph, and links the two families.

11. ADDUCTOR HYOMANDIBULAE (Figure 18a,fc).—

The muscle has a somewhat peculiar distribution.

It is present in balistids (but not monacanthids),

in the aracanid Kentrocapros (but not Capropygia),

in ostraciids, and in triodontids. In perciforms

(?thus plesiomorph), origin is from the prootic in

front of the adductor operculi. It is not certain

whether the tetraodontifonn condition is homologous with this, or, indeed, whether it is homologous within the tetraodontiforms themselves. In

the ostracioids it originates from the exoccipital

(Kentrocapros) or from the cleithral region (ostraciids), and this posterior origin is apparently

apomorph. Its absence in gymnodonts (other than

triodontids) is not suprising, since the hyomandibular becomes increasingly interdigitated with the

chondrocranium, and thus less mobile. Its absence

in triacanthoids may be due either to the fact

that they have independently lost the muscle, or,

more likely, because the muscle only developed

after they had split off from the other groups (in

which case the muscle is not homologous with its

perciform counterpart). Its absence in monacanthids could be due to subsequent loss.

In reexamining the situation, I assume that the

most generalized condition of the adductor arcus

palatini is when it stretches across the posterior

part of the floor of the orbit, and inserts on the

palatal arch, the hyomandibular, and the opercle

(forming the adductor operculi of more advanced

fishes). These points of insertion are close together,

and it is not unreasonable to assume a "polyphy-
78

letic" (i.e., independent) occurrence of the adductor hyomandibulae, which occupies the area

between the adductor arcus palatini and adductor

operculi. It seems probable that the triacanthoid

condition, where the muscle is absent, is plesiomorph for the tetraodontiforms. The common

balistoid + ostracioid-gymnodont ancestor developed a section (most likely from the adductor

operculi, with which the present muscle is in contact) which attached to the hyomandibular. In

the balistoid-ostracioid line, the insertion became

tendinous (ostracioids), while the muscle was lost

in the monacanthids (the reason why this should

be so is enigmatic). Among the gymnodonts, triodontids retain what is now the plesiomorph condition, while all the other families have lost the

muscle—probably because of the increasing interdigitation of the hyomandibular to the chondrocranium. Reinterpreted in this way, the

phylogenetic tree changes to that shown in Figure

18b.

12. INTERMANDIBULARIS (Figure 19a).—The presence of this muscle is plesiomorph in the Teleostei.

It is absent in the gymnodonts dissected, and this

is presumably associated with the firm suture or

fusion of the halves of the lower jaw, precluding

the normal lateral movement of these elements.

There is one exception to this general absence—it

appears as a healthy, well-developed muscle in the

tetraodontid Xenopterus. This is inexplicable in

normal evolutionary terms—it seems fatuous to

assume (1) that Xenopterus represents a lone, evolutionary line which split off from the gymnodont

stock before any of the other derivatives or (2)

that the muscle was present in the tetraodontid

line up until Xenopterus split off, being subsequently lost in the other species. The situation is

perhaps analogous to that found in the pleural

ribs of tetraodontiforms—they are found only in

Triodon and the monacanthid Pseudaluteres

(Tyler, pers. comm.). The single possible explanation is that an unblocking of the genetic code

governing the development of the muscle has occurred, possibly as a result of selection pressures

acting on one of the other facets of that gene complex's pleiotropism (i.e., atavism, sensu Rensch,

1959). Although this is not a particularly convincing argument, it is certainly easier to accept

than either of the above alternatives.

13. VALVULUS (Figure 196).—The muscle is

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

present as a "de novo" development in the gymnodonts only. It may arise from the protractor

hyoidei as a diffuse sheet (triodontids), or from

the interopercle (tetraodontids and the molid Ranzania), the angular (diodontids and the molid

Mola), or the preopercle (canthigasterids). The

triodontid condition would seem to be plesiomorph.

14. PROTRACTOR HYOIDEI.—Such variation as

occurs in this muscle cannot, at present, be used

in phylogenetic interpretation, either because it

is too sporadic, or because the character state cannot be satisfactorily determined.

15. HYOHYOIDEUS INFERIORIS (Figure 20a,b).—

In the apparently plesiomorph condition, the muscle passes from the anterohyal beneath the first

few branchiostegal rays to a midventral raphe. It

is connected to the ventrohyals by tendons arising

from its anterior surface. As such, it is found in

triacanthoids. In all other families, the tendons

are lost. The muscle is well developed in balistoids (in most monacanthid genera it is partially

attached to the urohyal) and poorly so (synapomorph) in the ostracioids. It is partially fused to

the protractor hyoidei in triodontids, but absent

in all other gymnodonts except molids, where it

is well developed.

In diodontids and tetraodontids, the loss (or

fusion) of the muscle is presumably associated with

the branchiostegal ray pumping mechanism. This

mechanism is not found in triodontids, but here

the pectoral and pelvic girdles closely underlie

the hyoid arch, inhibiting the amount of lateral

movement of the arch, and thus decreasing the

usefulness of the muscle; that is, it does not necessarily mean that triodontids share an ancestor with

diodontids and tetraodontoids, in which groups

the reduction has been completed. Figure 206

gives the resulting phylogeny.

16. HYOHYOIDEI ABDUCTORES (Figure 21a).

Many generalized perciforms possess these muscles

to the ventral six branchiostegal rays. Their number is usually four in tetraodontiforms (five in

some balistids, three to six in monacanthids). Balistoids are apomorph in that the muscle to the

first ray is enlarged, and often passes more dorsally

than the other muscles. Triodontids and molids

have three muscles, with the first broadly developed. The first branchiostegal ray of diodontids

and tetraodontoids is enormously enlarged, and

this is accompanied by an equally enormous, apo-
NUMBER 155 79

morph development of the muscle serving the ray.

Tetraodontoids have developed a medial fiber bundle which crosses the midline beneath the branchial arches above the ventral tip of the cleithrum.

This bundle is not as well developed or separated

in the diodontids.

17. HYOHYOIDEI ADDUCTORES (Figure 21&).—In

most perciforms, the muscle is usually somewhat

diffuse, and lies in the lateral wall of the opercular

cavity between and above the branchiostegal rays.

As such, it is found in triacanthoids and balistoids.

It is fairly well developed in the ostracioids, and

there is a ventromedial slip to the anterior face

of the cleithrum from the opercular valve. It is

well developed in triodontids. In the other

gymnodonts, it becomes even better developed,

and acquires attachment to the pterotic and

hyomandibular dorsally (although it is poorly

developed laterally in the molid Ranzania). In

diodontids and tetraodontoids, it is an extremely

powerful muscle, with some fibers passing from

the fascia between epibranchials 3 and 4 to the

posteromedial wall of the cavity. In tetraodontoids,

the posterolateral fibers form a semicircle around

the opercular valve, connecting the dorsal cleithrum

to the dorsolateral coracoid. Just below this, a

bundle passes anteriorly from the coracoid to the

cleithrum. The large development of the muscle

is gymnodonts (particularly in the last three families) is presumably associated with the increased

rigidity of the palatal arch, and the increased role

of the opercular cavity in respiration.

18. STERNOHYOIDEUS (Figure 22a).—In most

teleosts, this muscle is posteriorly continuous with

the obliquus inferioris body musculature, and inserts on the urohyal. As thus defined, it is found

in triacanthoids. In balistoids, a medial subdivision

develops which inserts on the ventral tip of the

urohyal. There may also be a horizontal subdivision as in some balistids (e.g., Rhinecanthus,

Balistapus) or the medial subdivision may be absent

(e.g., the monacanthid Oxymonacanthus). Ostracioids also possess this medial subdivision, but

here the muscle arises primarily from the fascia

between the cleithrum and the coracoid (synapomorph). In gymnodonts, the sternohyoideus is

small, and is not laterally continuous with the

obliquus inferioris. In diodontids and tetraodontids, the posteromedial fibers tend to sweep more

dorsally than anteriorly.

It is possible (but difficult to demonstrate) that

the medial section of the sternohyoideus in balistoids and ostracioids is involved in more complex

respiratory movements. The small size of the muscle in gymnodonts is again presumably associated

with a different breathing mechanism.

19. STERNOBRANCHIALIS (Figure 22b,c).—The

plesiomorph condition of this muscle is probably

such as is found among certain perciforms and

triacanthodids. Here the posteromedial fibers of

the sternohyoideus tend to pass dorsally and become attached (triacanthodids) to the median

septum separating the opercular cavities from each

other and from the heart. The fibers separate out

farther in triacanthids, balistoids, and ostracioids.

Insertion is still broad and somewhat diffuse in

triacanthids. In balistoids, the anterior aponeurosis

attaches to the urohyal, while the posterior one

inserts on hypobranchial 3. Two subdivisions are

also present in the ostracioids, the first including

hypobranchial 3 and the second including ceratobranchial 4 in sites of insertion (these subdivisions

in ostracioids are completely separate from each

other and the sternohyoideus). Both conditions appear to be synapomorph, apparently arising from

different directions of consolidation of the broad

aponeurotic sheet probably present in the common

ancestor. The muscle is absent in all gymnodonts.

In a broad context, this is plesiomorph, for the

muscle has seldom been reported in perciforms

(although Dietz, 1914:133, reports its presence in

gobioids, and the orientation of the posteromedial

fibers of the sternohyoideus in many acanthopterygians). If, however, one accepts that the gymnodonts are tetraodontiforms (and the evidence

is impressive), then it is true to say that the subsequent loss of the muscle is apomorph.

Since no tetraodontiform possesses well-developed

toothed, lower pharyngeals, and since the sternobranchialis attaches anteriorly onto the branchial arches, it seems that its presence must be

correlated with respiration (by aiding the depression of the branchial and hence hyoid arches), and

its absence may once again be referrable to the

branchiostegal ray pumping mechanism of the diodontids and tetraodontoids. This latter may not

be wholly correct, since the muscle is also absent

in triodontids and molids. Possibly it was originally

lost by a common ancestor similar to Triodon,

where the cleithrum closely underlies the branchial
80

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

basket (and hence there is little room for vertical

movement of the branchial and hyoid arches).

It is also possible that the similarity of the

triacanthid and balistoid-ostracioid condition is

due to parallel evolution. If the triacanthodid condition is plesiomorph for tetraodontiforms, then

the muscle may have become consolidated and

separated in those two lines independently. Thus,

the common balistoid + ostracioid-gymnodont ancestor may well have retained the triacanthodid

condition, and the gymnodonts themselves may

never have developed a sternobranchialis. This

view is expressed as an alternative in Figure 22c.

20. PHARYNGOCLAVICULARIS EXTERNUS (Figure

23a).—The muscle is consistently present in perciforms, tetraodontiforms, and many other fishes.

Variations found in tetraodontiforms were the

large development of the muscle in ostracioids, its

bifid nature in many monacanthids, the triple insertion in canthigasterids, and the medial position

relative to the pharyngoclavicularis internus in

diodontids. Only the first has phylogenetic significance, the other variations being autapomorphic.

21. PHARYNGOCLAVICULARIS INTERNUS (Figure

2$b).—Normally, this muscle passes horizontally

forward from the medial face of the deithrum to insert on the anteroventral surface of ceratobranchial

5. It is present in this form in triacanthodids,

ostracioids, and triodontids. In triacanthids, the

insertion is broad and by way of numerous tendons.

In molids, the whole muscle is broad and diffuse.

Balistoids are linked by the insertion of the muscle

on ceratobranchials 4 and 5. Diodontids and tetraodontoids are specialized in that some fibers insert

on basibranchial 3. In addition, tetraodontoids

possess a section of the muscle which crosses the

midline.

22. OBLIQUI VENTRALES (Figure 23c).—In most

fishes, there are three pairs of these muscles, which

span the ventral articulations between the ceratobranchials and hypobranchials of the first three

arches. Fibers of obliquus ventralis HI often attach to the arch-shaped ligament between the ventral processes of the third hypobranchials. This

condition is met with in triacanthoids and balistoids, with minor variations. In monacanthids, the

muscle of the second arch is absent; except in

Oxymonacanthus; the third muscle is also absent

in Anacanthus. In ostracioids, only obliquus ventralis III is present—a synapomorph condition linking the two families. Triodontids have lost the

muscle of the first arch, but the other two are

well developed. All other gymnodonts have lost

the arch-shaped ligament between the third hypobranchials. Molids and diodontids have all three

obliqui ventrales present, but only the third is

present in tetraodontoids. Although this could be

interpreted as a link between the tetraodontoids

and the ostracioids, I feel that the loss of the

arch-shaped ligament and associated muscle fibers

is far more subject to the laws of parsimony than

the postulated loss, in more than one phyletic line,

of muscles whose absence or presence is more

labile.

23. TRANSVERSI VENTRALES (Figure 24a).—Most

fishes possess two of these muscles, which connect

the ventromedial faces of the fourth and fifth

ceratobranchials across the ventral midline. There

is little variation in them in tetraodontiforms.

Transversus ventralis V consists of separate anterior and posterior sections in balistids. In monacanthid, both muscles consist of two sections, which

cross over each other in the midline (the relative

position of one to the other being variable). In

addition, there is a third transversus ventralis between the ventral tips of the third hypobranchials—the muscle apparently being formed from

fibers contributed by obliquus ventralis III and

rectus ventralis IV. Transversus ventralis IV is

single in the monacanthid Paraluteres. Canthigasterids possess only the fifth muscle—it seems

probable that the fourth has fused with that part

of the pharyngoclavicularis internus that crosses

the midline just ventral to the fourth ceratobranchials.

24. RECTI VENTRALES (Figure 246).—These muscles, which interconnect the basal regions of the

arches to one another, are of mosaic occurrence

in teleosts. The most frequent one (often called

the interarcuales IH/IV) connects the anterior tip

of ceratobranchial 4 to the ventral process of hypobranchial 3, usually with some fibers attaching to

the arch-shaped ligament between the hypobranchial processes. Triacanthodids and triodontids

have this muscle, as well as one between ceratobranchial 1 and the dorsohyal. Among the molids,

Mola has only the first rectus, while Ranzania also

possesses the second muscle. However, neither of

them possesses a rectus IV. In the triacanthids,

balistoids, and ostracioids, recti I, II, and IV are
NUMBER 155 81

present. Rectus II attaches primarily to the urohyal

or to its antimere where the urohyal is small or

absent (ostracioids). Balistoids are apomorph in

the possession of an extra section to the fourth

rectus (the original section being absent in the

monacanthids Paraluteres, Oxymonacanthus, Pseudalutarius, and Anacanthus, and poorly developed

in most other monacanthid genera). Diodontids

and tetraodontoids possess four rectus muscles, the

tetraodontoids being linked by the presence of a

lateral division of the first rectus, which attaches

to the lateral face of ceratobranchial 1 (canthigasterids) or to the dorsomedial face of the hyomandibular (tetraodontids). Since the arch-shaped

ligament between the ventral processes of the third

hypobranchials is absent in the last three families

mentioned, the fourth rectus attaches to the posterior face of the ventral process of hypobranchial

3.

25. RECTUS COMMUNIS (Figure 25a ).—The muscle is found throughout the acanthopterygian fishes,

and usually passes from the urohyal to the anteroventral face of ceratobranchial 5. It is present in

this condition in the triacanthoids, balistoids,

ostracioids, and triodontids. In certain monacanthid genera, two small bundles of muscle fibers

arise from the posterior face of transversus ventralis III and attach to the dorsal faces of the

tendons of this muscle. They apparently represent

the remains of the ventral sections of rectus IV,

whose posterior sites of attachment have shifted

from the anteroventral faces of the fourth ceratobranchials onto these tendons. The remaining families of gymnodonts have lost the urohyal, and

the muscle originates from the ventrohyal (except

diodontids, where the origin is from the posterior

face of basibranchial 1). Tetraodontoids are specialized in that both the origin and insertion are

tendinous, the muscle fibers being confined to a

belly in the middle of the length of the muscle.

26. LEVATORES EXTERN I (Figure 256).—There

are generally four of these muscles, which originate

from the prootic region of the skull beneath the

hyomandibular fossa and insert on the dorsolateral

faces of epibranchials 1-4. Often, as in a number

of tetraodontiform families, the manner of insertion varies—e.g., the muscle of the first arch may

send a slip of fibers to the second arch. Triacanthoids and triodontids exhibit the presumed plesiomorph condition. Balistoids and ostracioids are

linked by the fact that the origin of the muscles

is from the ventral surface of the prootic shelf,

which appears to have evolved for this purpose.

Ostracioids are apomorph in that the enlargement

of the shelf has allowed the anterior migration

of the branchial arches and the associated musculature to a position beneath the orbit. Gymnodonts

other than triodontids have the fourth levator

much enlarged. In molids, the entire origin of

these muscles is from the dorsomedial face of the

hyomandibular. Diodontids and tetraodontoids

have in common the even greater development of

levator IV, and the insertion of its posterior fibers

on the cleithrum. Origin here includes the pterotic

as well as the prootic (some fibers arising from

the hyomandibular in diodontids).

27. LEVATORES INTERNI (Figure 25c).—The muscles generally originate from the prootic, and, in

perciforms, insert on infrapharyngobranchials 2

and 3. They are found as defined above in triacanthoids and balistoids. Levator III usually lies somewhat lateral to levator II, and originates more

posteriorly. Ostracioids show an enormous development of these muscles, whose origin has expanded to include not only the prootic, but the

pterotic, epiotic, exoccipital, and (ostraciids)

parasphenoid as well. Much of the origin is thus

from the posterior face of the skull. In triodontids,

levator II inserts on infrapharyngobranchials 2

and 3, while in molids levator III inserts on these

bones. Diodontids and tetraodontoids are linked

by the posterior migration of the origin of levator

II to the pterotic, the fibers crossing medial to

those of levator III at an angle of about 45 degrees.

In the insertion of these muscles, tetraodontoids

are similar to molids, and diodontids more like

triodontids, but the character state at this level

is difficult to determine. Tetraodontoids possess a

medial connection of levator II to the lateral face

of transversus dorsalis III.

28. OBLIQUUS DORSALIS (Figure 26a).—Perciforms usually possess a single such muscle between

the infrapharyngobranchial and epibranchial of

the third arch. This condition is found in triacanthoids, balistoids (except the monacanthid Aluterus), aracanids, triodontids, and diodontids.

Balistoids have developed an additional anterior

section which connects infrapharyngobranchial 2

to epibranchial 3. Molids show some familial

variation. In Mola, most of the fibers attach to
82

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

infrapharyngobranchial 2, while in Ranzania an

obliquus dorsalis II has developed between the

infrapharyngobranchial and epibranchial of the

second arch (possibly being derived from transversus dorsalis II). Tetraodontoids are linked by

the fact that epibranchial 4 contributes partially

(tetraodontids) or wholly (canthigasterids) to the

lateral site of the muscle's attachment. In both

these families, fibers pass anteromedial to infrapharyngobranchial 2.

29. OBLIQUUS POSTERIOR.—The muscle is present

in all the tetraodontiform families except the

molids (it is also absent in the monacanthid Anacanthus). Frequently, fibers of this muscle intermingle with those of the sphincter oesophagi or

adductor V. Nothing could be deduced from it

phylogenetically.

30. TRANSVERSI DORSALES (Figure 266).—In the

plesiomorph condition, there are two such muscles

which connect the epibranchial, infrapharyngobranchial, or both elements across the midline

between the second and third arches. Triacanthoids

and balistoids exhibit this condition, except that

most of the fibers of transversus II arise from the

lateral face of the parasphenoid instead of from

the midline. In the latter group, some fibers of

transversus III may attach to epibranchial 4. Ostraciids, on the other hand, have four such muscles,

inserting on epibranchials 1-4. The fibers serving

epibranchials 3 and 4 are poorly separated from

each other. Gymnodonts appear to show almost all

possible sites of insertion. In triodontids, the anterior muscle inserts on epibranchial 4 and infrapharyngobranchial 2, the posterior one attaching

to epibranchial 3. Molids have an anterior muscle passing posterolaterally from the parasphenoid

to infrapharyngobranchial 2 (and epibranchial 3

in Ranzania). Diodontids possess the anterior muscle to the third epibranchial and infrapharyngobranchial, while the fibers of the posterior muscle

insert on epibranchial 4. In tetraodontids, transversus II arises partially from the parasphenoid,

inserting on infrapharyngobranchial 1, epibranchials 1 and 2, the medial face of levator internus

II, with some fibers passing to the wall of the

opercular cavity. Transversus II inserts on epibranchials 3 and 4. Canthigasterids have the anterior

muscle to infrapharyngobranchial 2 and the medial

face of levator internus II, and the posterior fibers

to epibranchial 4. In view of this incredible diversity, phylogenetic interpretation does not seem

warranted, except to state that the tetraodontids

and canthigasterids are sister groups, since they

share the unique anastomosis of fibers with those

of levator internus II.

31. RETRACTOR DORSALIS (Figure 27a).—This

muscle, which, in the plesiomorph condition, connects infrapharyngobranchial 3 to the anterior portion of the vertebral column, is found as such in

triacanthoids and ostracioids. All other families have

become specialized in the site of insertion, origin,

or both, and all (with one exception) in different

ways. In both balistoid families, the origin of the

muscle has shifted anteriorly onto the lateral face

of the basioccipital, the insertion remaining on

infrapharyngobranchial 3.

32. ADDUCTORES (Figure 27b).—In most teleosts, there are two of these muscles, adductor IV

connecting the medial faces of the fourth epibranchials and ceratobranchials and adductor V connecting ceratobranchial 5 to epibranchial 5 or,

when that bone is absent (as in most fishes), to

epibranchial 4. This latter condition is met with

in triacanthoids, balistoids, triodontids, and molids.

Ostracioids are linked by the loss of adductor V

(ostraciids having lost adductor IV as well). In

diodontids and tetraodontoids, each arch possesses

an adductor (except the tetraodontid Arothron,

where adductores III and IV are absent).

33. SPHINCTER OESOPHAGI (Figure 27c).—The normal condition of this muscle, where it simply encircles the esophagus behind the gill arches, is

found in the triacanthoids. Balistoids are linked

by the possession of a bundle of fibers passing

dorsomedially from epibranchial 4 to infrapharyngobranchial 3, while ostracioids possess a pair of

ventral tendons attaching to the medial faces of

the cleithra, and lack a section of the muscle passing anterodorsal to the retractor dorsalis. Gymnodonts all have a longitudinal bundle of fibers

passing posteriorly from at least one infrapharyngobranchial, and all of them except the triodontids have a similar orientation of the anteroventral

fibers. Diodontids, canthigasterids, and some tetraodontids possess a lateral bundle passing anterior

to (and sometimes attached to) the epibranchialceratobranchial region of the fourth arch. In addition, the ventral longitudinal bundle in these three

families attaches to the basibranchials (to the

third in diodontids and tetraodontids, where it
NUMBER 155 83

seems to be plesiomorph, and to the first in canthigasterids). Tetraodontids and canthigasterids

have also developed a partial separation between

the more dorsal longitudinal bundle and the ventral transverse component of the ventral region

of the muscle.

34. ABDUCTOR SUPERFICIALIS (Figure 28a).—The

fibers originate from the posterior face of the ala

laminaris externus and the lateral cleithrum behind it. Tendons insert on the anterolateral bases

of the principal fin rays. The only variation of

phylogenetic significance in tetraodontiforms is

found in diodontids and tetraodontoids. Here,

some ventral (diodontids, canthigasterids) or all

the rays (tetraodontids) develop anterodorsal

flanges from their bases, at the same time losing

the posteroventral flange. Consequently, the tendon of the abductor superficialis inserts on the

flange rather than on the anterodorsal base of the

ray. Molids lack flanges on the fin rays, both laterally and medially.

The development of the anterodorsal flange appears to be related to the more vertical axis of

the fin, and would seem to allow better control

of the fin rays.

35. ABDUCTOR PROFUNDUS (Figure 28&).—The

muscle arises from the coracoid and posterior cleithrum beneath the abductor superficialis, and inserts on the tips of the posteroventral flanges of

the principal and vestigial fin rays. In diodontids

and tetraodontoids it inserts on the posteroventral

base of the shaft of some ventral or all the rays,

for the reasons discussed above. Both monacanthids

and diodontids lack a section of the muscle to the

vestigial fin ray, but the former do not possess

the anterodorsal flanges of the ventral fin rays.

36. ARRECTOR VENTRALIS.—Origin is from the

lateral face of the cleithrum above and beneath

the abductor superficialis, the fibers inserting tendinously on the anterolateral face of the medial

half of the vestigial fin ray. No significant variations were noticed in the tetraodontiforms examined.

37. ADDUCTOR SUPERFICIALIS (Figure 28c).—

There is little variation in the form of this muscle among tetraodontiforms. However, diodontids

and tetraodontoids have developed dorsally directed flanges on the ventral six to nine rays, with

a concomitant loss of the ventral flanges. The

tendons serving these rays insert on the flanges

rather than on the shaft of the rays distal to their

bases. The possible explanation is the same as

that advanced for the analogous flanges on the

lateral halves of the rays, as discussed under the

abductor superficialis

38. ADDUCTOR PROFUNDUS (Figure 29a).—Once

again, little can be said except that the diodontids

and tetraodontoids apparently share a common

ancestor, the ventral six to nine tendons inserting

at the base of the ray instead of on the now nonexistent ventral flanges.

39. ARRECTOR DORSALIS (Figure 296).—Origin

of the muscle is primarily from the medial face

of the cleithrum, the insertion being on the medial

face of the vestigial fin ray. All gymnodonts show

a considerable reduction of the muscle, which, in

addition, becomes covered medially by the adductor muscles (the latter also occurs in aracanids,

but here the arrector dorsalis is well developed).

40. CORACORADIALIS (Figure 29c,d).—The fibers

of this muscle generally connect the posterodorsal

region of the coracoid to the posteroventral face

of the fourth radial, in the apparently plesiomorph

condition. As such, it is found in triacanthodids,

monacanthids, aracanids (small), triodontids, and

tetraodontids. In balistids and triacanthids it is

a well-developed muscle, originating mainly from

the fascia over the medial face of the adductor

profundus; in ostraciids and molids it is absent;

and in diodontids some of the dorsal fibers are

continuous with fibers of the obliquus inferioris.

The two former apparently synapomorph conditions give rise to the phylogeny in Figure 29c.

In the above analysis, the muscle's form was

interpreted as linking the triacanthids and balistids as sister groups, and also linking the ostraciids

and molids together. To take the latter first, there

is a reductive trend in the ostracioids—the muscle

is small in aracanids and absent in ostraciids.

Molids are unique in possessing an anterior prong

of the postcleithrum which articulates with the

lateral surfaces of the radials. It is doubtful

whether the radials are very mobile under these

circumstances (the apparent function of the coracoradialis), and it is not surprising that the muscle

is absent in molids.

The large form of the muscle and its position

medial to the adductor series in triacanthids and

balistids is difficult to explain in terms of the

proposed phylogeny. It should theoretically either
84

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

be present in this form in all the families (in

which case it has reverted to the ancestral condition in four separate lineages—triacanthodids,

monacanthids, ostracioids, and gymnodonts), or

else it has reached the same modified, enlarged

condition separately in triacanthids and balistids.

The former seems unlikely. The latter is possible,

especially if one could offer an explanation as to

why this should occur, and what advantage (s) it

confers. However, this cannot be done until the

function of the muscle has been accurately determined, and its influence on the mechanism of the

pectoral fin defined.

41. ADDUCTOR RADIALIS (Figure 30a).—This

muscle is present in many perciform groups, and

is found in the triacanthoids, where it inserts on

a maximum of three rays. It is absent in all other

tetraodontiform families.

42. PROTRACTOR PECTORALIS (Figure 30&).—The

muscle is consistently present in most euteleosts

including tetraodontiforms (except the ostracioids).

It arises from the pterotic and inserts on the anterodorsal face of the cleithrum. In molids, it is

reduced to a thin strip of fibers. In diodontids and

tetraodontoids, the muscle inserts on the anterodorsolateral face of the cleithrum, and, in tetraodontoids, part of the muscle attaches to the

supracleithrum. This seems to be associated with

the operation of the postcleithral apparatus (see

Winterbottom, 1971a, for details).

43. LEVATOR PECTORALIS (Figures $0c,d).—In

most perciforms and triacanthodids, the muscle

passes from the pterotic to the supracleithrum,

cleithrum, or both. Triacanthids possess a cleithrum which abuts firmly against the skull, and

the muscle is absent. It is also absent (apparently

for a similar reason) in ostracioids. In balistoids,

it attaches to the anterodorsomedial rim of the

cleithrum, mainly in front of the supracleithrum.

In all gymnodonts, the fibers pass posteromedially

to the supracleithrum to insert on the tip of the

posterodorsal extension of the cleithrum. In

molids, the muscle is much reduced, but still passes

medial to the supracleithrum to attach to the cleithrum (Figure 30c).

In the above analysis, the point of disagreement

is the linking of the triacanthids and ostracioids

by virtue of the absence of the muscle. In both

cases, the reason appears to be the very firm attachment of the pectoral girdle to the skull, resulting in the decrease or loss of movement of the

girdle. However, this seems to have taken place

for different reasons. In triacanthids, it is associated

with increased support for the pelvis and the pelvic

spines. In ostracioids, there is no pelvis, and the

increased rigidity results from the close association

of the pectoral girdle with the bony cuirass of the

exoskeleton, (Figure 30d).

44. ARRECTOR DORSALIS PELVICUS (R.T.) (Figure

31a).—This muscle, which is found in most perciforms and a number of other fishes, originates

from the dorsolateral face of the pelvis and inserts

on the pelvic spine. It is present in triacanthoids,

but absent in all other tetraodontiform families.

The great development of the muscle relative to

the presumed plesiomorph condition in the triacanthoids seems synapomorph. However, the

loss of the muscle may be synapomorph, or it may

have occurred in more than one lineage. Although

the former view is tentatively followed here, the

presence of a rather normal-looking pelvis and

pelvic fin in the Eocene Eoplectus may mean that

it has been lost independently in the gymnodom

and the balistoid-ostracioid lineages.

45. ARRECTOR VENTRALIS PELVICUS (R.T.) (Figure

316/r).—The fibers of this muscle arise from the

ventral face of the pelvis and insert on the pelvic

spine. It is extremely well developed in the triacanthoids (more so than in the presumed plesiomorph condition exemplified by perciforms), much

reduced (or absent—five genera of monacanthids)

in balistoids, and absent in all the other families.

The absence of the muscle in ostracioids and

gymnodonts needs reinterpreting, since it is apparently the result of parallel evolution. Ostracioids have lost the pelvic girdle as a result of the

development of the exoskeleton; in gymnodonts,

its reduction and loss is either associated with the

body form (molids) or with the inflatory abilities.

It is not certain whether the muscle followed the

same reductive processes in the balistoids and

ostracioids (i.e., the balistoid condition may be

plesiomorph for the two groups), and therefore

its presence cannot be used to link the balistids

and monacanthids.

46. ADDUCTOR SUPERFICIALIS PELVICUS (R.T.)

(Figure 32a,&).—In percifonns, the muscle inserts

both on the pelvic spine and on the pelvic fin

rays. A single slip to a pelvic fin ray was found

only in the triacanthodid Parahollardia. The sec-
NUMBER 155 85

tion to the pelvic spine is very well developed in

triacanthoids, much reduced and passing through

a bony canal in balistoids (absent in five monacanthid genera), and absent in all the other families.

In the reinterpretation of this muscle, the reasoning used for the arrector ventralis pelvicus applies in the same way, except that the passage of

the tendon through a narrow, bony canal in

balistoids is considered to be synapomorph, and

thus links the two families as sister groups.

47. ADDUCTOR PROFUNDUS PELVICUS (R.T.) (Figure 32c).—Among the perciforms, this muscle inserts on the bases of the pelvic fin rays. It is found

only among members of the Triacanthodidae (but

is absent in seven of the genera—see Winterbottom, 1970).

Since this muscle is very much reduced, and

frequently absent, in the triacanthodids, the trend

in its reduction seems obvious. It is, therefore,

better to assume that no phylogenetic information

can be deduced from it at present.

48. INCLINATORES DORSALES (R.T.pars) (Figure

$5a,b).—In the apparently plesiomorph condition, these muscles originate from the fascia

overlying the epaxialis and insert on the lateral

bases of the spines and rays of the dorsal fin. They

are present to the spines only in the triacanthoids,

where triacanthodids may have up to six (inserting

on the spines and the basal pterygiophores) and

triacanthids possess two to four (inserting only on

the pterygiophores). The muscles attach to all the

dorsal fin rays in triacanthoids, balistoids, and

triodontids. They are much reduced or absent in

all the other families (0-1 in aracanids and diodontids, absent in molids and ostraciids, 2 to the

posterior rays in canthigasterids, and continuous

with the transverse cutaneous attaching to the

pterygiophores in tetraodontids—see Figure 33a).

In the initial interpretation, the ostracioids were

linked with the gymnodonts minus triodontids.

This was based on the loss or reduction of the

muscles in these families. In ostracioids, the loss

seems to be associated with the large development

of the erector and depressor dorsales muscles, and

the reduction and freeing of the dorsal moiety of

the epaxialis (their normal site of origin). This is

taken a step further in molids, where the epaxialis

almost entirely disappears, and the erector and depressor muscles are enormously enlarged. Inclinators

are also reduced or absent in diodontids and tetraodontoids, possibly because the fibers become associated with the transversus cutaneous system. In

addition, there may well be an elusive, functional

reason. In all cases where the muscles are reduced

or absent, the fin is short based, and, when used in

locomotion, it flaps synchronously from side to side

with the anal fin (Figure 336).

49. ERECTORES DORSALES (R.T.pars) (Figure 34a,

6).—Generally, these muscles are fairly small, and

insert on the anterolateral base of each spine and

fin ray. In the spiny dorsal fin, triacanthodids possess up to six, triacanthids up to five, while there

are two in balistoids and triodontids. Since there

is overlapping variation in the first two families,

these muscles cannot be used to differentiate between them. They are absent in all other families

(which do not possess a spiny dorsal fin). Those to

the fin rays are much enlarged in ostracioids, and

are enormous, being partially to wholly fused to

the depressors in molids (Figure 34a).

In the initial analysis, the ostracioids were linked

with the gymnodonts (minus triodontids). This

is apparently the result of a reductive trend, since

the former group would have little use for a spiny

dorsal fin (being encased in thick, bony armor)

and, as in the gymnodonts mentioned, loss of the

spiny dorsal fin may well be associated with the

posterior migration and small size of the soft dorsal

fin (Figure 346).

50. DEPRESSORES DORSALES (R.T.pars) (Figure

54c,d).—In the most plesiomorph condition, each

spine and fin ray receives a depressor muscle. There

are up to six in the spiny dorsal fin of triacanthodids, up to five in triacanthids, three in balistids,

two in most monacanthids, and one in triodontids.

The muscles to the fin rays are enlarged in ostracioids, and fused to the erectors in molids.

Once again, a reductive trend is apparent. The

postulated ancestor of the balistoids + ostracioids

+ gymnodonts must have possessed a spiny dorsal

fin. This is retained symplesiomorphly in the

balistoids, but lost in the ostracioids (the same

reasoning used for the erectores dorsales applies

here). Triodontids are plesiomorph in the retention of a single depressor to the spiny dorsal fin,

the fin being absent in all the other gymnodonts.

51. INCLINATORES AN ALES (Figure 35a).—These

muscles generally insert on the lateral bases of all

the anal fin rays. In all families (except most

ostracioids) there is a residual inclinator attaching
86

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

to the distal face of the first basal pterygiophore.

It is well developed in balistoids, and attaches to

the tip of the postcleithrum in most tetraodontoids.

There are 0-2 normal inclinators in diodontids,

and four in canthigasterids. Molids show two extremes in the form of the residual inclinator. In

Ranzania, the muscle attaches to the base of the

pterygiophore and fades into the subdermal connective tissue, while in Mola it attaches to the tip

of the postcleithrum but does not reach the

pterygiophore. It is therefore described as part of

the obliquus inferioris, for it seems as likely to be

part of this muscle as to be an inclinator.

Inclinators to the fin rays are reduced (tetraodontoids) or absent (most ostracioids, some diodontids and molids). In view of the intrafamilial

variation, no interpretation will be placed on this

facet of the distribution of the muscle.

52. ERECTORES ANALES (Figure 35&).—The only

variation found in this muscle complex is in ostracioids (where the origin is more lateral owing to

the divergent nature of the pterygiophores) and

in molids (where the muscles are enormously developed, and partially to wholly fused with the

depressores anales).

53. DEPRESSORES ANALES (Figure 35<r).—The remarks made in connection with the erectores anales

apply to this muscle complex as well.

54. SUPRACARINALES ANTERIOR (R.T.) (Figure

$6a,b).—The muscle usually passes from the supraoccipital region of the skull to the first pterygiophore of the dorsal fin. As such, the muscle is

present in triacanthoids, balistids, aracanids, and

triodontids. It is absent in monacanthids and

ostraciids, being small and largely tendinous in

molids. In diodontids and tetraodontoids, the

lateral fibers insert on the dorsomedial faces of

the first few bifid neural spines (Figure 36a).

The reduction and loss of this muscle has occurred in the monacanthids (where the pterygiophore of the spiny dorsal fin has become firmly

attached to the cranium) and ostraciids (where

the long pterygiophore to which the muscle attaches in aracanids is greatly reduced). Thus, the

processes that resulted in the loss of this muscle

are different in the two families (Figure 366).

55. SUPRACARINALIS MEDIUS (Figure 36c).—The

muscle appears to have arisen a number of times

during the evolution of the teleosts. It occupies

the dorsal midline between the two dorsal fins,

where these are separate. In the tetraodontiforms,

its presence is apomorph, and it is found only in

the balistoids. These two families are the only

ones where the anterior migration of the spiny

dorsal fin has separated it from the soft dorsal fin.

In all other forms (apart from the triacanthoids),

the spiny dorsal fin has apparently migrated

posteriorly.

56. SUPRACARINALIS POSTERIOR.—In the normal

teleostean condition, this muscle connects the last

pterygiophore of the soft dorsal fin with the neural

spine of the last complete vertebra, attaching to

the tips of the neural spines of the intervening

vertebrae. The variations found in tetraodontiforms are both autapomorphs—the muscle is absent

in molids, and attaches to the dorsomedial faces

of the bifid neural spines in diodontids.

57. INFRACARINALIS ANTERIOR (R.T.) (Figure

37a,b).—In the apparent plesiomorph condition

(such as is found in most teleosts), the fibers

originate from the posteroventral regions of the

cleithrum and coracoid and pass posteriorly to

insert on the anteroventrolateral face of the pelvis.

Triacanthoids are apparently synapomorph in that

the muscle has partially fused with both the arrector dorsalis and ventralis pelvicus. In balistoids,

the muscle inserts in a lateral fossa along the

anterolateral face of the pelvis, while in triodontids

it inserts on the lateral face of that bone. It is

much reduced and intermingles with the longitudinal cutaneous in tetraodontoids, and is absent

in ostracioids, molids, and diodontids (in which

latter family it has probably become fully incorporated in the longitudinal cutaneous, losing

both sites of origin and insertion).

The loss of this muscle in ostracioids is correlated with the loss of the pelvis and the absence

of any alternative function for the muscle to perform, such as is found in diodontids and tetraodontoids. This is probably also true of the molids.

As pointed out, it seems likely that in the diodontids the muscle has become completely incorporated into the longitudinal cutaneous system.

58. INFRACARINALIS MEDIUS (R.T.pars) (Figure

37c,d).—The muscle normally connects the posterior edge of the pelvis with the anteroventrolateral face of the first basal pterygiophore of the

anal fin. It is usually in intimate contact with the

obliquus inferioris dorsally. Triacanthodids are

apparently autapomorph in the distinct separation
NUMBER 155 87

of the muscle from the obliquus inferioris. In

diodontids and tetraodontoids, the fibers join with

the obliquus inferioris in giving rise to the longitudinal cutaneous system, the former family having

lost the anterior connection of the muscle with

the cleithrum. It is absent in ostracioids and

molids (Figure 37c).

The absence of the muscle in the two latter

groups is probably due to the same causes as

postulated in paragraph 57 for the infracarinalis

anterior. This involves the independent loss of

the pelvis and the concomitant lack of an alternative function for the muscle to perform (with the

same explanation of its presence in diodontids and

tetraodontoids).

59. INFRACARINALIS POSTERIOR.—The muscle connects the last basal pterygiophore of the anal fin

to the last haemal spine or the parhypural. The

only significant variation noted in tetraodontiforms

was the absence of the muscle in molids.

60. INTERRADIALIS. (Figure 38a). — In most

teleosts, this muscle interconnects the lateral faces

of the caudal fin rays together, lying a little distal

to their bases. It is absent in molids. In diodontids

and tetraodontoids, the fibers tend to course vertically (rather than at an anteriorly inclined angle),

and also tend to be superficially continuous.

61. HYPOCHORDAL LONGITUDINALIS. (Figure 38

b).—Origin is from the ventral hypural region, often

including the parhypural and the ural centrum.

The plesiomorph condition for the tetraodontiforms seems to involve the insertion of the tendons

on dorsal caudal rays D 3-5. This condition is

found in triacanthodids, triodontids, and ostracioids. In triacanthids, the muscle inserts on rays

D 3-4, in balistids on D 2-5, and in monacanthids

on rays D 1-3. Diodontids and most tetraodontoids

have the tendons inserting on rays D 2-4, and this

is apparently apomorph for the group. The muscle

is absent in molids.

62. FLEXOR DORSALIS (Figure 38c).—In most

perciform fishes, this muscle originates from the

centra and neural spines of the last few caudal

vertebrae, and inserts on the bases of all the dorsal

branched caudal fin rays. This condition is found

in triacanthids and balistids. In ostracioids, the

muscle is partially (aracanids) or wholly (ostraciids) fused to the overlying epaxialis. Triacanthodids (except the two long-snouted genera)

have lost the uppermost and lowermost sections.

In triodontids, the origin is limited to the ural

centrum, and there is no tendon to ray D 1. Insertion is variable in diodontids, but is on the

ventral three (canthigasterids) or four (tetraodontids) of the dorsal caudal rays in tetraodontoids.

The muscle is absent in molids.

63. FLEXOR DORSALIS SUPERIOR (Figure S9a,b).—

The plesiomorph condition of this muscle is apparently as it is found in perciforms and triacanthodids, where it is small, and originates from

the distal tips of the neural spines of the last

few vertebrae. In all other tetraodontiforms, at

least some fibers arise from the vertebral centra,

and the muscle is considerably larger. In all

families except triacanthids, the fibers partially

cover the flexor dorsalis laterally. In ostracioids,

the muscle is fairly small, and inserts on D 5, while

in balistoids it is large and originates mainly from

the neural spines. The plesiomorph condition

here is probably considerably smaller than in the

balistoids but larger than in the ostracioids. In

diodontids and tetraodontoids, the muscle is well

developed, the origin being mainly from the

vertebral centra and the neural arches, the insertion usually being on ray D 5. It is absent in

molids.

The loss of the muscle in molids is autapomorph,

and does not necessarily exclude them from the

phylogenetic tree. One other aspect seems to require further analysis. The expansion of the

muscle, and its origin (at least partially) from

the vertebral centra in all but triacanthodids suggests that these families shared a common ancestor

possessing this condition. At present, only one

other group of teleosts is known to exhibit this

enlargement of the muscle—the Acanthuridae

(Monod, 1959c, fig. 10; Winterbottom, 1971b, fig.

2). What this means in terms of the phylogeny

of these groups remains, for the moment, an

enigma. However, the presence of such a specialized condition in an extremely closely related

group of fishes is difficult to ascribe to convergence.

In view of the low neural spines of triacanthids,

and thus the likelihood of the flexor dorsalis

superior contacting the vertebral column (provided, of course, it is not lost as, for example, it

is in scombrids and many other forms with slender

peduncles and lunate caudal fins), the triacanthid

condition seems more likely to be due to convergence than to synapomorphy. The character
88

can still be used to group the balistoid + ostracioid

+ gymnodont fishes as a monophyletic lineage

whether or not the acanthurids belong to the

assemblage, since we are, for the present, only

concerned with the interrelationships of the

"tetraodontiform" fishes as they are usually conceived (Figure 396).

64. FLEXOR VENTRALIS (Figure 40a). — The

muscle forms the ventral counterpart of the flexor

dorsalis. Description of the plesiomorph condition

is similar—origin is from the centra and haemal

spines of the last few vertebrae, the ural centrum,

and the ventral hypurals; insertion is on the bases

of the branched ventral caudal fin rays. As such,

it is found in triacanthoids, balistoids, triodontids,

and some tetraodontoids. It is partially (aracanids)

or totally (ostraciids) fused to the overlying

obliquus superioris in ostradoids. The insertion is

reduced to three fin rays in diodontids (and to

two in certain tetraodontoids), and the muscle is

absent in molids.

65. FLEXOR VENTRALIS EXTERNUS (Figure 406).—

The muscle, which in the normal perciform condition connects the haemal spines and centra of

the last few vertebrae with the bases of ventral

caudal fin rays V 1-2, is present in triacanthoids

and gymnodonts (except molids). It shows little

variation in these groups, except in two genera of

tetraodontids. It is absent in all balistoids and

ostradoids, but for a different reason from that

in molids, where all intrinsic caudal fin muscles

have been lost.

66. FLEXOR VENTRALIS INFERIOR (Figure 40c,d).—

The plesiomorph condition appears to be for

most perciforms, where the origin is from the

tip(s) of the haemal spine (s) of the last (few)

vertebra (e), and the muscle is small. This state

is met with in the triacanthodids. In the other

families, it arises from the ventrolateral faces of

the centra (triacanthids) or the lateral surfaces

of these centra. In balistoids, it is large, with

much of the origin from the haemal spines,

although many fibers arise from the centra. The

origin is not as extensive in ostracioids, and both

conditions are apparently synapomorph. It arises

more from the centra and the haemal arches

(rather than haemal spines) in diodontids and

tetraodontoids, and it is absent in molids.

The reasoning followed in the reinterpretation

of this muscle is exactly the same as used for the

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

flexor dorsalis superior (paragraph 63).

67. TRANSVERSUS CAUDALIS (Figure 41a,6).—In

perciforms which possess this muscle, it arises from

the dorsolateral region of the hypurals and inserts

on the base of ventral caudal fin ray VI . It is

present in this form in triacanthodids, balistoids,

and triodontids. In ostracioids, it inserts on at

least three rays, not including VI . It inserts

partially on V 2 in canthigasterids and most

tetraodontids. It is absent in diodontids, triacanthids, and molids.

In reinterpreting, the molids can be removed

from this group, since they lack all intrinsic

caudal fin musculature (in which respect they are

autapomorph). In perciforms which possess this

muscle, it is usually reduced or absent in forms

with a lunate tail fin—presumably because this

type of fin requires a more rigid attachment of

the fin rays, and hence less movement is possible.

It is absent (possibly for this reason) in triacanthids, and is small in the other family with a

lunate fin, the triodontids. I can offer no explanation for the absence of the muscle in

diodontids, except that I consider Grenholm's explanation (1923:239-240) unlikely. Grenholm suggests that the flattened posterior margin of the

hypural plate allows considerable vertical movement of the fin rays, rendering the transversus

caudalis redundant. This is, however, a purely

destructive criticism.

68. EPAXIALIS (Figure 41c).—In most fishes,

this division forms the main component of the

dorsolateral body musculature. In the plesiomorph

condition (found to some degree in the triacanthoids), the anterior myocommata pass posterodorsally near the dorsal midline. The other

tetraodontiform families have lost almost all

traces of this final change of direction of the

myocommata. In ostradoids, the dorsal of the

two main moieties (i.e., where the myocommata

pass anterodorsally) separates from the ventral

section in front of the dorsal fin, and, owing to

the enlargement of the erector-depressor complex,

few, if any, of the medial fibers attach to the

vertebral column. In addition, the ventral fibers

tend to fuse with the dorsal fibers of the obliquus

superioris posteriorly. In all gymnodonts (except

molids, which are autapomorph) the dorsal moiety

becomes aponeurotic posteriorly, joining a similar

aponeurosis from the obliquus inferioris to insert
NUMBER 155

on the bases of all the caudal fin rays.

69. LATERALIS SUPERFICIALIS.—This muscle, which

covers the anterior portions of the epaxialis and

obliquus superioris laterally, is undoubtedly present

in at least some triacanthoids and balistoids. However, it is an extremely difficult muscle to identify

and delimit (the more so in preserved material,

where it loses its distinctive red coloration), and

usually requires histological examination in order

to describe satisfactorily. It will therefore not be

considered in the phylogenetic analysis.

70. OBLIQUUS SUPERIORIS (Figure 42a).—In the

plesiomorph condition for perciforms (not found

in tetraodontiforms), this muscle is not separate

from the obliquus inferioris. The fibers pass from

posteroventral to anterodorsal, coursing in the opposite direction in the latter section. The sections

may also be recognized by the direction of the

myorommata, which is the same as that of the

fibers, but at a greater angle. In tetraodontiforms,

these sections are usually well separated and

variously modified. The anterior region in all

is much reduced, and does not cover the abdominal

cavity dorsolaterally. In balistoids and ostracioids,

the anterior fibers do not reach the posterodorsal

face of the clei thrum. The fibers apparently fuse

with the epaxialis posteriorly in ostracioids. In

molids, the muscle is absent except for a small

posterior section serving the ventral caudal fin

rays, and, in Mola, a thin, diffuse sheet extending

anteriorly in the subdermal tissue. The muscle is

much reduced anteriorly in diodontids, and arises

from the vertebral centra above the swim bladder.

71. OBLIQUUS INFERIORIS (Figure 426).—The

plesiomorph condition of this muscle was described

under the obliquus superioris above. It is extensively modified in tetraodontiforms, particularly

in those gymnodonts with inflation abilities. It

will therefore be discussed under a series of section

headings, following Winterbottom (1971a) where

applicable.

Section A: Present only in tetraodontoids as a

small, partially separated division, originating from

the posterodorsal process of the coracoid and inserting on the ventral postcleithrum. The fibers

forming this section are present in most families

of tetraodontiforms, but are not separated from

the rest of the muscle.

Section B: This portion is present in tetraodontoids and diodontids only. Origin is from the

medial faces of the cleithrum and coracoid, the

fibers attaching to the ventral postcleithrum. The

more ventral fibers pass medial to section A. and

are ventrally continuous with the dorsal fibers of

section C.

Section C: The dorsal fibers of this section give

rise to sections A and B in the forms described

above. Thus, in tetraodontoids, only a few fibers

of this section attach to the ventral postcleithrum,

and none do so in diodontids, where the bone is

much reduced.

The fibers in other families arise from the

lateral faces of the cleithrum and coracoid (being,

in most cases, continuous with the sternohyoideus

anteriorly), and pass posteriorly to attach to the

postcleithrum dorsally. The more dorsal fibers

continue dorsally as section D. In tetraodontoids,

the ventral fibers attach to the base of the first

pterygiophore of the anal fin. In all forms except

molids (where a patch of anterior fibers may remain—Mola) and diodontids, the posteroventral

fibers continue posteriorly, usually being firmly

attached to the ventral region of the obliquus

superioris. In diodontids, these fibers arise from

the ventrolateral process of the sixteenth vertebra.

In all gymnodonts (except molids, where this portion is absent), the fibers grade into an aponeurosis

which joins a similar aponeurosis from the dorsal

moiety of the epaxialis to form a tendinous sheath

inserting on the bases of all the caudal fin rays.

In addition, all gymnodonts (except molids and

one genus of tetraodontid) possess a posterodorsomedial bundle of fibers which arises from the

main mass of the muscle just in front of the anal

fin, and courses up and back, medial to all muscles

save the erector-depressor complex of the anal fin,

to attach tendinously to the tips of one or more

haemal spines. Fibers pass anteriorly from the

region of the anal fin into the subdermal tissue

in diodontids and tetraodontoids (where they contribute to the formation of the longitudinal

cutaneous).

Section D: The fibers arise from the fascia in

the region of the lateral septum, and pass anteroventrally to insert on the posterodorsal face of

the postcleithra. The section is well developed

in triacanthoids, most balistoids, and gymnodonts

(except molids, where it is absent). In diodontids,

it attaches to the first and last pterygiophores of

the dorsal fin and the last pterygiophore of the
90

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

anal fin in some species. In canthigasterids, some

fibers reach the first pterygiophore of the dorsal

fin. The section is much reduced or absent in

ostracioids.

72. SPINAUS (Figure 43a,&).—Little, if anything, has been reported in the literature about

this muscle and its distribution. It is present in

triacanthids and balistoids. In the former, it arises

from the posterior face of the first pterygiophore

of the spiny dorsal fin and attaches to the tips of

the neural spines of the second to fifth vertebrae.

In balistoids, it originates from the epiotic and

inserts primarily on the neural spine of the third

vertebra.

Although the muscle appears to indicate the

sister group status of triacanthids and balistoids,

this is unlikely in view of the large amount of

evidence placing the ostracioids as the balistoid

sister group, these two then forming the gymnodont

sister group. A second alternative is that the

triacanthids form the sister group of the balistoid +

ostracioid + gymnodont line. This necessitates

the postulated loss of the spinalis in ostracioids

and gymnodonts. In view of the anatomical differences between the muscles in the two groups

possessing it, our meager knowledge of its distribution in fishes, and its probable derivation

from the anterior most epaxial myomere, neither

alternative is particularly satisfying. The origin

of the muscle from the epiotic in balistoids will,

for the present, be considered synapomorph

(Figure 436).

73. TRANSVERSUS CUTANEOUS (Figure 43c).—

This name is used for two, apparently nonhomologous muscles. In balistoids, the muscle

arises from the lateral face of the pelvis and passes

dorsally into the fascia over the obliquus inferioris

in the region of the ventral tip of the postcleithrum, to which it may attach. In diodontids

and tetraodontoids, it lies in the subdermal tissue,

being best developed ventrally.

74. LONGITUDINAL CUTANEOUS (Figure 43d).

The muscle system is present in diodontids and

tetraodontoids. It is best developed ventrally,

where the infracarinalis medius and obliquus

inferioris contribute to its formation. The tetraodontoids also possess well-developed fibers anterodorsally.

75. SWIM BLADDER MUSCLES.—These muscles are

present in only two families. They are not homologous structures. In ostraciids, the anterior region

of the swim bladder possesses two layers of fibers

passing at different angles to each other. In

diodontids, there is a vertical bundle of fibers on

the posterior face of the -swim bladder, and there

may be another bundle anteriorly between the

two halves of the bladder.

Discussion

Of the 75 muscles analyzed in the preceding

section, seven (9 percent) yielded no interpretable

phylogenetic information, 18 (24 percent) initially

disagreed with the hypothesized phylogeny (Figure

44) while 50 (67 percent) confirmed it to greater

or lesser extents. Out of the 18 muscles disagreeing

with the hypothesis, only five (sternobranchialis,

coracoradialis, flexor dorsalis superior, flexor ventralis inferior, and spinalis) seem to be important,

the others being easily explained by normal

evolutionary phenomena such as reductive trends.

It may well be significant that these five muscles

(of which the coracoradialis is a dubious member)

indicate some sort of connection between the

triacanthids and the nontriacanthoid tetraodontiforms. This possibility is analyzed in more detail

under "Branch Point 1."

In the weighting of characters, it is apparent

that little emphasis can be placed on those subject

to parallel evolution, since more than one interpretation is possible. Furthermore, it seems to

me that synapomorphs resulting from reduction

and "serial homologues" (such as certain branchial

arch muscles, and those of the dorsal and anal

fins) carry less weight than shifts in origin and

insertion, and the development of new muscles.

Myers (1958) points out that reduction is one ot

the chief mechanisms of specialization in teleosts,

but since it is apparently easier for two groups

to lose a common structure than it is for them to

independently develop a morphologically identical

one, the latter seems worthy of greater emphasis in

the interpretation of phylogeny (see also Weitzman, 1964:150).

One other point seems worthy of specific mention at this stage. We have already seen that

groups can only be linked by synapomorph characters. Should the hierarchical units one is dealing

with (in this case, families) have evolved so that

each of the main branch points ultimately gives
NUMBER 155 91

rise to more than one unit, synapomorphs must

be present in both these lines. If one line gives

rise to, say, families A and B, while the other

divides into a number of families, the fact that

the families of the second branch may share many

synapomorphs indicates only that they themselves

share a common ancestor, i.e., it does not tell

us whether these families are most closely related

to family A, family B, or the ancestor of both

A and B. For this reason, the lines of the branch

points are labeled "a" and "b" in Figure 44, and

the letter after each muscle used in the analysis

below indicates the line in which that character

is synapomorph. Where the character indicates a

common ancestor for the two lines, the letters are

omitted; both are included if the muscle is apparently synapomorph in both lines, but does

not give any evidence of a common ancestor for

these lines. Toward the end point of the branching, where lines contain only two families, synapomorphs linking the members of each of these

families to each other are not listed, since this

would require examination of all the genera contained in every family to be valid.

The letters "a" and "b" mentioned above appear as suffixes to a parenthesized numeral behind

each muscle mentioned. This numeral refers to

the number used to denote the muscle in the

section on the phylogenetic significance of the

myological differences observed.

BRANCH POINT 1

The phylogeny proposed from the analysis of

the musculature suggests that the families Triacanthodidae and Triacanthidae form the sister

group of all the remaining tetraodontiforms.

Specialized characters supporting this contention

are: section A 1 of the adductor mandibulae (lb);

adductor hyomandibulae (lib); adductor radialis

(41b); arrector dorsalis pelvicus (44a,b); arrector

ventralis pelvicus (45a); adductor superficialis

pelvicus (46a); inclinatores dorsales (48b); erectores dorsales (49b); depressores dorsales (50b);

infracarinalis anterior (57a); flexor dorsalis superior (63b); flexor ventralis inferior (66b); and

epaxialis (68b).

It is fairly obvious that this collection of synapomorphs is by no means convincing. Although

the evidence is good for the sister group status

of the balistoids + ostracioids to the gymnodonts

(10 characters), the linking of the triacanthodids

and triacanthids as sister groups is very weak (4

characters). Furthermore, these four characters are

ones which required reinterpretation. The justification is mainly based on the form of the

triacanthoid pelvis. This complex is extremely

unusual, possessing large pelvic spines which can

be locked in position, and a well-developed posterior elongation of the pelvis behind the articulation of the fin. Should the triacanthodids and

triacanthids not be sister groups, then we must

postulate that such a structure was present in

the tetraodontiform ancestor. This in turn implies

that the nontriacanthoid tetraodontiforms have

reversed the evolutionary trend, reducing the spines

(and ultimately losing them); and exhibiting the

posterior migration of the pelvic fin along the

posterior elongation of the pelvis.

Furthermore, the fossil Eoplectus (see "Alternative Interpretations"), which is an early gymnodont,

possesses a normal-looking perciform I 4 pelvic fin

(although the presence or absence of a posterior

elongation cannot be determined). The presence

of this apparently extremely specialized character

complex in triacanthodids and triacanthids seems

to me to indicate the sister group status of these

two families, and that their common ancestor

developed this condition after splitting off from

the line giving rise to all the other tetraodontiform

families. In addition to this, both triacanthoid

families possess the same locking mechanism for

the large first dorsal spine (a mechanisn which

differs considerably from that of both balistoids

and acanthurids).

It should perhaps be remarked here that the

extremely similar dorsal and pelvic spine locking

mechanisms of at least some members of the

Zeiformes (e.g., Capros apex) require further

examination, and, until our knowledge of the

various anatomical systems of the zeiforms has substantially increased, the possibility of a close relationship between at least some of them and

triacanthoids should not be entirely ignored.

There is a certain amount of myological evidence

which would appear to indicate a somewhat different picture of the basal evolution of the

tetraodontiforms—namely, that the triacanthids

form the sister group of the nontriacanthoid

families, and that these together form the sister
92

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

group of the triacanthodids. Although these possibilities have been discussed in the interpretive

section, it seems pertinent to review them here.

The condition of the anterior region of the adductor arcus palatini of triacanthids is somewhat

reminiscent of what one would deduce to be the

beginnings of the development of a retractor arcus

palatini, and thus may suggest that triacanthids

form the balistoid-ostracioid sister group. However, the reason for the absence of the muscle in

gymnodonts is readily apparent, (i.e., the interdigitation of the palatine to the ethmoid-vomer

region of the skull. Furthermore, such an intermediate condition (although not as well developed

as in triacanthids) is also found in certain chaetodontin and pomacanthin fishes, and a welldeveloped and separated retractor arcus palatini is

present in acanthurids. It is therefore conceivable

that the triacanthid condition is a response to

the somewhat elongated ethmoid region rather

than being due to synapomorphy.

A sternobranchialis muscle (in varying stages of

separation from the sternohyoideus) is present in

all families but the gymnodonts. This muscle has

only been reported elsewhere in certain gobioids

(Dietz, 1914). I feel that the explanation for the

absence of the muscle in gymnodonts is satisfactory,

and it seems that we can assume that such a

muscle, probably in a state of differentiation similar

to that found in present-day triacanthodids, was

present in the ancestral tetraodontiforms.

The specialized condition of the coracoradialis,

too, is of dubious significance, being present only

in triacanthids and balistids. If triacanthids did

form the sister group of balistoids, balistoids +

ostracioids, or of all nontriacanthoid tetraodontiforms, one would nonetheless expect the presence

of the specialization in monacanthids, instead of

the plesiomorph condition of the muscle, which

is what they in fact possess. It appears that this

character is somewhat labile, and, as stated, it is

necessary to accurately determine its functional

role before the significance of the triacanthidbalistid condition can be interpreted.

The presence of a flexor dorsalis superior and

a flexor ventralis inferior which have origins at

least partially from the vertebral centra in triacanthids and all nontriacanthoid tetraodontiforms

is another factor suggesting the sister group relations of these two groups. However, as pointed

out, acanthurids possess a form of these two

muscles which is apparently identical to the

balistoid condition. Whether this is due to synapomorphy or convergence cannot, for the moment,

be ascertained and must await further study. In

view of this, and because of the apparent ease with

which the triacanthids could exhibit a condition

similar to the nontriacanthoid tetraodontiforms (see

"Interpretation"), it seems dangerous to place much

emphasis on these characters.

Lastly, the spinalis is found in triacanthids and

balistoids. This is probably the most telling character. The absence of the muscle in ostracioids

and gymnodonts poses little difficulty, since in

these fishes the neural spines are broad and platelike, and do not appear capable of much movement (the apparent function of the spinalis).

Should, however, the spinalis prove to be involved

in curving the vertebral column, then it is possible

that the muscle has differentiated independently

in the two lineages, and is perhaps involved in

the better positioning of the dorsal spines.

However these muscles are interpreted, I feel

that the acceptance of the phylogeny postulated

here for these groups involves mental exercises of

a less deep-seated nature than would be indulged

in if one were to attempt to explain away the

pelvic fin and pelvis of the triacanthoids, to say

nothing of the synapomorphs linking the nontriacanthoid tetraodontiforms.

BRANCH POINT 2

This dichotomy suggests that the balistoids +

ostracioids form the sister group of the gymnodonts.

Evidence supporting this is derived from the following muscles: section A 1 of the adductor

mandibulae (la); section A © of the adductor

mandibulae (4b); levator arcus palatini (5a); dilatator operculi (6a); levator operculi (7a,b); adductor arcus palatini (8a); retractor arcus palatini

(9a); intermandibularis (12b); valvulus (13b);

hyohyoideus inferioris (15a,b); hyohyoidei abductores (16b); hyohyoidei adductores (17b);

sternohyoideus (18a,b); sternobranchialis (19a—

alternative interpretation); levatores externi (26a);

sphincter oesophagi (33b); arrector dorsalis (39b);

levator pectoralis (43b); arrector ventralis pelvicus

(45b); adductor superficialis pelvicus (46b); depressores dorsales (50b); flexor ventralis externus
NUMBER 155

(65a); epaxialis (68b); and obliquus superioris

(70a).

Of the 24 muscles listed, 11 have become synapomorph in the balistoids + ostracioids and 15 in

the gymnodonts, which indicates that the former

are slightly more plesiomorph than the latter.

Given, then, that the ancestral species at Branch

Point 2 was, in fact, the common ancestor of the

balistoids, ostracioids, and gymnodonts, there is

convincing evidence that the balistoids and ostracioids form one line, and the gymnodonts the

other.

BRANCH POINT 3

This branch point separates the balistoids as the

sister group of the ostracioids. The synapomorph

conditions are present in the following muscles:

section A 1 (lb), section A 2 (2a,b), and section

A 3 (3b) of the adductor mandibulae; dilatator

operculi (6); levator operculi (7a); adductor arcus

palatini (8b); retractor arcus palatini (9); adductor

operculi (10b); adductor hyomandibulae (lib);

hyohyoideus inferioris (15b); hyohyoidei abductores (16a); hyohyoidei adductores (17b); sternohyoideus (18b); sternobranchialis (19—alternative

interpretation); pharyngoclavicularis externus (20

b); pharyngoclavicularis internus (21b); obliqui

ventrales (22b); transversi ventrales (23a); recti

ventrales (24a,b); levatores externi (26b); levatores interni (27b); obliquus dorsalis (28a);

retractor dorsalis (31a); adductores (32b); sphincter oesophagi (33a,b); coracoradialis (40b);

protractor pectoralis (42b); levator pectoralis

(43b); arrector ventralis pelvicus (45b); adductor

superficialis pelvicus (46a,b); erectores dorsales

(49b); depressores dorsales (50b); inclinatores

anales (51a,b); erectores anales (52b); depressores

anales (53b); supracarinalis medius (55a); infracarinalis anterior (57a,b); infracarinalis medius

(58b); flexor dorsalis (62b); flexor dorsalis superior

(63a,b); flexor ventralis (64b); flexor ventralis inferior (66a,b); transversus caudalis (67b); epaxialis

(68b); obliquus superioris (70b); obliquus inferioris (71b); spinalis (72a); and transversus

cutaneous (73a).

Of the 48 synapomorphs listed above, 16 occur

in balistoids and 36 in ostracioids, which clearly

places the balistoids as the plesiomorph sister group

of the ostracioids.

BRANCH POINT 4

The hypothesis presented here is that the Triodon tidae form the sister group of the other gymnodont families. The evidence is provided by the

following synapomorphs: section A 1 (lb), section

A 2 (2b), and section A <o (4b) of the adductor

mandibulae; adductor hyomandibulae (lib);

valvulus (13); hyohyoidei adductores (17); obliqui

ventrales (22b); rectus communis (25b); levatores

externi (26b); sphincter oesophagi (33); erectores

dorsales (49b); depressores dorsales (50); and

obliquus inferioris (71).

The evidence seems fairly conclusive, and would

probably be more so were it not for the autapomorph loss of the intrinsic caudal fin musculature in molids.

BRANCH POINT 5

The hypothesis is that the Molidae form the

sister group of the tetraodontoids and diodontids.

Synapomorphic evidence is furnished by the following muscles: section A 1 (1), and section A 2

(2a) of the adductor mandibulae; levator arcus

palatini (5); dilatator operculi (6a); hyohyoideus

inferioris (15a); hyohyoidei abductores (16a);

hyohyoidei adductores (17); sternohyoideus (18a);

pharyngoclavicularis internus (21a); recti ventrales

(24a); levatores externi (26); levatores interni

(27a); adductores (32a); sphincter oesophagi (33);

abductor superficialis (34a); abductor profundus

(35a); adductor superficialis (37a); adductor profundus (38a); protractor pectoralis (42a); inclinatores dorsales (48a); supracarinalis anterior (54a);

infracarinalis anterior (57a); infracarinalis medius

(58a); transversus cutaneous (73a); and longitudinal cutaneous (74a). There are 25 synapomorphs listed, and it is likely that this number

could be greater were it not for the autapomorph

condition of the intrinsic caudal fin musculature of

the molids.

BRANCH POINT 6

This branch point suggests that the Diodontidae

form the sister group of the Tetraodontidae and

Canthigasteridae. Evidence is derived from the

following synapomorphs: section A 1 of the adductor mandibulae (1); dilatator operculi (6a);
94

adductor arcus palatini (8a); hyohyoidei abductores

(16); hyohyoidei adductores (17); pharyngoclavicularis interims (21); obliqui ventrales (22a); recti

ventrales (24); rectus communis (25a); levatores

interni (27); obliquus dorsalis (28a); transversi

dorsales (30a); sphincter oesophagi (33); protractor

pectoralis (42); infracarinalis anterior (57); flexor

dorsalis (62a); transversus caudalis (67a); obliquus inferioris (71); and longitudinal cutaneous

(74).

Of these 19 synapomorphs, the infracarinalis

anterior (57) and the transversus caudalis (67) may

be autapomorph in diodontids, and hence inadmissible as evidence. Even so, there seems no reason

to doubt that the Diodontidae separated off first

from the line which ultimately gave rise to the

Canthigasteridae and Tetraodontidae.

Alternative Interpretations

The vast majority of previous anatomical works

on the tetraodontiforms have been taxonomically

oriented. Phylogeny is seldom expressed, for although hierarchical levels were established in

classifying these fishes, it is only recently becoming

recognized that the phylogeny should be reflected

in the systematic hierarchy.

Among the more recent works purporting to

deal with the phylogeny of the tetraodontiforms,

few, if any, have been influenced by synapomorph

characters alone, and fewer still seem to have taken

reductive trends (with the implied "parallelism")

into account. Thus, the family tree presented by

Breder and Clark (1947) is largely one of morphological and ontogenetic similarity-dissimilarity,

with little attempt to conform the classification

to the phylogeny as it is proposed. Fraser-Brunner,

even in his last paper on tetraodontiforms (1951),

made but few phylogenetic observations, and his

planned monograph on these fishes has yet to

appear. The quality of Le Danois' work (1955,

1959, 1961) has already been alluded to, and may

be dismissed.

The provisional classification of Greenwood, et

al. (1966), while it is implicity phylogenetic, is (in

the section on tetraodontiforms) a slight modification of Regan's (1903) system, in which the Triodontidae are placed with the tetraodontoid fishes,

and Regan's suborder raised to ordinal status. No

evidence is given by Greenwood, et al., but, as they

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

point out (1966:391), much remains to be done

in the sorting out of the perciform and derived

families, and the Tetraodontiforms (among others)

are specifically mentioned in this respect.

In the more recent works of Tyler (1968, 1970a)

on the osteology of tetraodontiforms, some tentative phylogenetic conclusions are drawn, and these

will be discussed in detail below.

In examining alternative interpretations of

tetraodontiform phylogeny, certain lineages postulated in this study will not be broken down to

the family level, either because they are widely

accepted, or because the evidence presented here

is felt to be virtually conclusive. Thus, neither the

balistoids + ostracioids nor the gymnodonts will

be considered as other than single entities, each

derived from a single common ancestor. The

potential problems, then, lie in the basal phylogeny

of the order, where the evidence presented here

is weakest. There are four extant groups (Triacanthodidae, Triacanthidae, balistoids + ostracioids, and gymnodonts) whose phylogenetic

interrelationships are open to different interpretations. To these can be added a fifth, since Tyler

(1968, fig. 6) postulates that the subfamily Triacanthodinae forms the sister group of all other

living triacanthoids and balistoids. Tyler's views

are expressed graphically in Figure 45.

Unfortunately, Tyler's provisional interpretation is based on the autapomorph conditions of the

supraoccipital, first anal pterygiophore, and pelvic

basin in triacanthodins (i.e., these characters are

plesiomorph in the hollardiins and triacanthids,

and hence both are invalid as phylogenetic evidence). To prove, however, that the triacanthodid

subfamilies are more closely related to each other

than to any other living group, one needs to find

synapomorphic characters linking them. This becomes extremely difficult where the groups are

postulated as being the most plesiomorph members alive today. The triacanthodids are apparently

specialized in the complete separation of the infracarinalis medius from the obliquus inferioris,

since the muscle is partially continuous with, or

at least firmly attached to, the obliquus inferioris

in all other tetraodontiforms and most perciforms.

In his discussion of the relationships of triacanthoids to the balistoids, Tyler (1968:34) lists a

large number of characters shared by triacanthids

and balistoids (most, but not all, also being present
NUMBER 155 95

in the ostracioids). Nearly all these character

conditions may also be found in acanthurids (including the flange of the pterotic overlying the

posterodorsal region of the hyomandibular, and

the meeting and suturing of the pterosphenoids in

the midline). This brings the state of these characters into question—if the acanthurids form the

sister (or a close) group to the tetraodontiforms,

then it is reasonable to assume the triacanthidbalistoid condition is one of symplesiomorphy (in

which case the triacanthodid subfamilies are synapomorph, and the characters cannot be used to

link the triacanthids and balistoids phylogenetically). If on the other hand, the characters are

specialized, then there is osteological evidence that

the acanthurids are more closely related to the

triacanthids, balistoids, or both than they are to

anything else still extant. It is obvious that a

detailed osteomyological study of acanthurids,

siganids, chaetodontins, and other related fishes is

urgently needed to clear up the state of many of

these characters.

It seems necessary at this point to consider the

nature of the triacanthoid pelvis in the light of

the fossil evidence. As already noted, the pelvis

of these fishes has a very well-developed posterior

elongation behind the equally well-developed

pelvic spine. As stated under "Branch Point 1,"

one must either postulate (1) that this is a

plesiomorph condition for the tetraodontiforms as

a whole, or (2) that it represents a shared, specialized character complex strongly suggesting that

these two families possessed a common ancestor

with this condition, and that this ancestor did not

give rise to any other known tetraodontiform group.

If the former is the case, then we must postulate a

reversal in evolutionary trend, for the balistoid

pelvis, while elongate, has, at its distal tip, a bifid

structure which probably represents the pelvic

spines. In other words, either the pelvic fin itself

has migrated backward along the posterior elongation of a triacanthoid-like pelvis, or this posterior

elongation has been reduced and resorbed so that

the fin lies once more near the distal margin of

the pelvis. The second of the above postulates (2)

receives some support from the newly described

fossil, Eoplectus bloti Tyler from the Eocene of

Monte Bolca. Although systematically Tyler (1973)

places this specimen in the Triacanthodidae, he

states that it is phylogenetically closely related to

the gymnodonts, possessing the remarkable combination of jaw and dental features of this group.

The incomplete Zignoichthys oblongus (Zigno)

has been redescribed by Tyler in the same paper

(1973). It appears to be closely related to

Eoplectus, but may be farther along the line

toward modern gymnodonts. The two alternatives

are given as 4 and 3, respectively, in the phylogenetic tree in Figure 47. In addition to the

plesiomorph character of five or six dorsal spines,

Eoplectus has a perciform-like I 4 pelvic fin, the

balistoid-ostracioid condition of the large ventral

flange on the parasphenoid, and the second basal

pterygiophore of the spiny dorsal fin oriented

similarly to that of the balistids. From the evidence

provided by these fossils, it seems reasonable to

conclude that the common ancestor of the balistoids

+ ostacioids and the gymnodonts had a pelvic fin

of the normal perciform type (less one ray—the

condition of the posterior part of the pelvis is

unknown); at least five dorsal spines (six if the

phylogenetic placement of the Spinacanthinae is

correct—see below); the anterior pterygiophores

of the spiny dorsal fin relatively far forward and

possibly in contact with the skull; the shaft of the

second pterygiophore being directed anteroventrally; a large ventral flange on the parasphenoid;

pleural ribs with epipleurals; procurrent caudal

fin rays; and the maxilla immovably articulated

with the premaxilla, which lacked an ascending

process. Such a fish, should it have existed, is a

far cry from the triacanthoids of today, and it

certainly seems quite feasible that the triacanthoids

are the result of a single common ancestor that

diverged from the line, which gave rise to the other

tetraodontiform families.

The relationships of the tetraodontiform families

to the Acanthuridae (here conceived as including

the Zanclinae, following Tyler, 1970b) poses something of a problem. Although not enough information is at hand to warrant valid conclusions, it

seems necessary to hint at the possible relationship

of acanthurid fishes to the balistoid-ostracioidgymnodont lineage, forming the sister group of this

assemblage, and together with it forming the sister

group of the triacanthoids. In spite of the fact

that there is little osteological evidence to support

such a contention (indeed much of the evidence

is weighted against it—see Tyler, 1970a:42-43;

1970b), there is, on superficial examination, con-
96

siderable myological evidence (e.g., the form of the

adductor mandibulae; a retractor arcus palatini;

and the form of the flexor dorsalis superior and

flexor ventralis inferior). Whatever the relations

of the acanthurids to the tetraodontiforms may be,

there is enough information to make it apparent

that considerable "convergent" evolution has occurred (i.e., the development of morphologically

very similar characters, or the common loss of many

osseous elements in independent lines).

Although fossils do not provide myological information, a discussion of such forms as have been

discovered is essential to any study purporting to

be phylogenetic. Much of the information comes

from Tyler's (1968) excellent summary of fossil

triacanthoids.

Tyler (1968) placed the Spinacanthinae as a

subfamily of the Triacanthodidae, and considered

them to be the most basal group of the order (i.e.,

the sister group of all other tetraodontiforms),

mainly on the basis of the extremely well-developed,

six-spined dorsal fin. The two monotypic genera,

Spinacanthus [S. cuneiformes (Blainville)] and

Protobalistum [P. imperiale (Massolonga)], are

from the upper Eocene of Monte Bolca. Tyler's

objections to these fishes having balistoid affinities

are the six-spined dorsal fin and the short-based

soft dorsal and anal fins. The former objection

falls away, since Eoplectus has at least five (and

probably six) dorsal spines, and this must have

been the condition of the common ancestor of

the gymnodonts and balistoids + ostracioids. The

fact that the spines are better developed than in

any other tetraodontiform seems irrelevant, for

it could just as easily be an apomorph condition

as a plesiomorph one, and besides, dorsal spine

reduction is apparent independently in the triacanthoid, gymnodont, and balistoid-ostracioid

lines, the spines being better developed in the fossil

examples. Short-based soft dorsal and anal fins,

while not found in Recent balistoids, are present in

ostracioids and gymnodonts (with a few secondary

exceptions), and the character is, in the Spinacanthinae, plesiomorph (i.e., the state of the fins is

as one would postulate for the ancestor at Branch

Point 2), the longer based balistoid fin thus being

synapomorphic. Evidence that the Spinacanthinae

belong to the balistoid-ostracioid lineage rather

than the gymnodont line is provided by the

elongate ethmoid region between the upper jaw

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

and the eye, and the small eye high up on the

head. It seems quite possible that the spinacanthins represent the sister group of the modern

balistoids for two reasons. First, the dorsal spines

have migrated anteriorly onto the skull, whereas

the basal pterygiophores of the now-absent spiny

dorsal fin in ostracioids have migrated posteriorly.

Second, Eocene ostracioid fossils are known from

the same formation (having already lost the dorsal

spines and pelvis), whereas balistoids are first

known from the Oligocene.

The Protacanthodinae (Tyler, 1968:237-238) apparently represent an offshoot of the triacanthodidlike stock leading toward the triacanthids. This

agrees basically with Tyler's (1968) concept, except

that I would derive the balistoids (and the other

nontriacanthoid groups) from a slightly more basal

position, before the separation of the protacanthodins. The reduction of all but the first dorsal

spine and the elongate soft dorsal and anal fins

of protacanthodins are apparently synapomorphic

with the triacanthid condition, while they share the

form and configuration of the pelvis with triacanthoids generally. Tyler's placement of Acanthopleurus and Marosichthys in close proximity

to the triacanthids seems undeniable.

The last fossil which seems pertinent to this

discussion is Cryptobalistes brevis (Rath), placed

in its own subfamily by Tyler (1968:243-249). Of

this extremely confusing Oligocene fossil, Tyler

(1968:247) has said, "Cryptobalistes simply is not

on a lineage which led to any Recent balistids or

to any other Recent fishes, even though it has

paralleled the fundamental trends within the

Triacanthidae-Balistidae line of evolution." The

reader is referred to Tyler for the reasoning behind

this statement. Concerning the phylogenetic position of the fossil, the apparently synapomorph

nature of the basin-like pelvic shaft with that of

Recent triacanthodins seems to be the only pertinent character, and the subfamily is tentatively

placed as the extinct sister group of the triacanthodins (although this must imply that the hollardiins

diverged somewhat before the Oligocene from the

triacanthodins).

Vom Rath's specimens (one in counterpart, the

other single) are no longer at Bonn (pers. comm.

H. K. Erben, Institute fur Palaontologie, Bonn)

and every effort to relocate them for reexamination

has failed. The description given by vom Rath
NUMBER 155 97

(1859) is sparse, but the figure looks much like

a balistid with a triacanthoid pelvis and pelvic

fin. Should Cryptobalistes ultimately prove to be

(in spite of Tyler's statement quoted above) a

balistoid sister group, it may be that the posterodorsal flange of the balistoid pelvis represents

the posterior elongation in the process of resorbtion. However, such a postulate raises certain

difficulties. It seems fairly clear that Cryptobalistes

would be on the balistoid line rather than the ostracioid or ostracioid + balistoid one if it should

prove in any way related to these forms. The 11 synapomorphs listed under "Branch Point 2" which

link the ostracioids and balistoids seem to be

powerful ones, and the sister group status of these

two groups is extremely likely. If so, then

balistoids and ostracioids separated from their

common ancestor well before the Eocene, for

ostracioid fossils, apparently fully differentiated, are

known from Monte Bolca. Until more specimens

of Cryptobalistes are found, or the original specimens rediscovered, it seems safer not to form any

firm ideas on the position of the genus, and I have

accordingly followed one of Tyler's (1968) interpretations.

There are thus two main likely points of difference from the interpretation of tetraodontiform

phylogeny postulated here. One of these involves

the sister group status of the triacanthodids and

triacanthids, which has been extensively discussed,

and, although I believe the triacanthoid pelvis

to be a significant synapomorph, it is quite possible

that the triacanthodids separated off first from the

ancestral stock (thus forming the sister group of

all the other tetraodontiform families) and that

they were followed soon after by the triacanthids

(which thus would form the sister group of all the

nontriacanthoid families). The other point is my

placement of the gymnodonts as the sister group

of the balistoids + ostracioids. Tyler hinted

(1962c:800) that the gymnodonts share a common

ancestor with the triacanthoids + balistoids +

ostracioids (= his Sclerodermi), but in a later paper

(1970a: 29) he states that ". . . the Triodontidae

have on other grounds been considered as the

most generalized family of the suborder Gymnodontes, the latter probably derived from the basal

Sclerodermi." By "basal Sclerodermi," Tyler presumably means the triacanthoid fishes, but he does

not commit himself as to whether the gymnodonts

are derived from a pretriacanthodid, pretriacanthid,

or prebalistoid + ostracioid stock. Since the latter

case is the one presented here, and since no formulated arguments or alternatives have been proposed

to this hypothesis as yet, further discussion awaits

new evidence or reinterpretation of the old.

One last point may be mentioned in connection

with the postulated sister group status of the

balistoids + ostracioids and the gymnodonts—

their normal method of locomotion involves the

synchronous, side-to-side flapping of the dorsal and

anal fins. The possible exception to this is Triodon,

which has small dorsal and anal fins and a somewhat lunate caudal fin. This is probably a secondary condition (particularly since the caudal

fin of ^Eoplectus and nearly all other gymnodonts

is rounded). It therefore seems likely that this

method of locomotion was developed by the postulated common ancestor of these fishes. It also

appears likely that an in-depth study of the

anatomical systems associated with these fins will

reveal further synapomorphs linking the two

superfamilies, particularly in the fields of neurology,

osteology, and myology.

My own views on the phylogenetic positions of

the fossil groups discussed above are incorporated

in Figure 47.

A New Classification of the Tetraodontiformes

The importance of the distinction between

phylogeny and systematics has already been emphasized, and the ideal system would appear to

be one of phylogenetic systematics, i.e., a classification of animals in a hierarchical manner such that

the phylogeny of the components is accurately

represented. There is, at present, no method of

doing this. In a hierarchical phylogenetic classification, no taxon (be it species, genus, or family)

can contain more than two subtaxa, since the

moment a third subtaxon is added, a new rank

has to be imposed in order to preserve the phylogenetic information. The use of the classical,

hierarchical system results in a number of, say,
98

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

families within a superfamily, and it is impossible

to deduce the phylogeny of the contained units.

The establishment of a classification based on

"coordinate" units poses a number of apparent

problems at the present time. Since no taxon can

be the evolutionary equivalent (in the strict sense

of the word) of any other, it seems that one cannot imply equivalency in the hierarchical ranking

of taxa. Logical extension of the Hennigian

methods in these directions appears to lead ultimately to a ranking system of classification without

the imposition of arbitrary levels of implied

equivalency (such as family and genus). Although

the naming of all branch points may be the final

result, it appears to be unnecessary for the present

(unless an immediate purpose is served by doing

so). The hierarchical classification presented here

is, therefore, provisional, pending the outcome of

the attention currently directed to the discussion

of these problems. The relative time of branching

(i.e., the phylogeny) has been indicated by the

development of the following method, which allows

for the inclusion of more than two subgroups in

any group, the phylogeny of the contained units

being indicated by a simple system of numbers

(derived from the phylogenetic tree) behind each

taxon. The first taxon to diverge is suffixed by 1,

the second by 2, and so on. Should any of these

lines subsequently radiate, the resulting units could

be labeled (if the radiation took place in the

lineage labeled, say, 2) 2 in the case of sister

groups, or, if there were three resulting lines, 2,

2.1, 2.1, where the units labeled 2.1 are sister

groups, and together form the sister group of 2.

The above would only arise, of course, if the

taxa were to be treated as equivalent hierarchical

units. It can be seen from the following example

(which contains more units than would normally

be encountered) that each prime number contains the taxon (or taxa) whose sister group is

composed of all taxa with a larger prime number

(Figure 46).

Using the method of interpretation put forward

above, we get:

Taxon A (1) Taxon E (3.2) Taxon I (5.1)

Taxon B (2) Taxon F (3.2) Taxon J (5)

Taxon C (3.1) Taxon G (4) Taxon K (6)

Taxon D (3.1) Taxon H (5.1)

The main difficulty with this system is that one

is forced to make arbitrary decisions as to what

constitutes any given hierarchical level. It is

obvious that definitions based on morphological

dissimilarity will only lead to confusion if used

in a phylogenetic classification, since they ignore

Hennig's "Rule of Deviation" (1966:207). Hennig's suggestion that hierarchical levels be determined by their geological age is more logical,

even if still arbitrary and sometimes clouded by

our lack of knowledge. By suggesting only broad

stages, Hennig (1966:185) "makes it possible for

the time being to reserve the well known category

designation ('class' and 'subclass') for the more

important and morphologically isolated groups.

All possibilities of future refinement of the method

remain open." This view can apply equally well

to lower categories, and there seems to be no reason

why the phylogeny should not be indicated (where

necessary) by the numerical suffix method outlined

above. Where it has not proved possible to

elucidate the phylogeny, there is no cause to

reject the system prevailing prior to the investigation. That changes in systematic rank may

result in applying phylogenetic findings to the

classification is irrelevant, since hierarchical levels

are completely arbitrary, and have, in the past,

been based solely on the amount of similaritydissimilarity, without regard for the state of the

characters.

The following phylogenetic tree is drawn up

from the myological evidence presented in this

paper, to which has been added my views on the

phylogenetic position of the various fossil groups.

Where alternative branch points are shown, the

dashed line represents the less likely possibility.

The numbers (1 and 2, 3 and 4) are used to indicate the alternatives in the hierarchical classification presented after Figure 47.

The hierarchical arrangement of these groups

thus becomes:
NUMBER 155 99

1. Suborder Triacanthoidei

Family Triacanthodidae

Subfamily Triacanthodinae (1)

Subfamily? tCryptobalistinae (1)

Subfamily Hollardiinae (2)

Family Triacanthidae

Subfamily Triacanthinae

Subfamily tProtacanthinae

Suborder Tetraodontoidei

Superfamily Balistoidea

Family tSpinacanthidae (1)

Family Balistidae (1)

Subfamily Balistinae

Subfamily Monacanthinae

Family Ostraciidae (2)

Subfamily Aracaninae

Subfamily Ostraciinae

Superfamily Tetraodontoidea

3. Family fEoplectidae (1)

Family fZignoichthyidae (2)

Family Triodontidae (3)

Family Tetraodontidae (4)

Subfamily Tetraodontinae

Subfamily Canthigasterinae

Family Diodontidae (4)

Family Molidae (5)

The following systematic and hierarchical changes

are suggested in order to bring tetraodontiform

classification into line with the phylogenetic relationships postulated in this paper:

1. That two suborders be provisionally recognized (Triacanthoidei and Tetraodontoidei), the

first containing two families, the second consisting

of two superfamilies.

2. That a superfamily Balistoidea be recognized,

containing the families f Spinacanthidae, Balistidae,

and Ostraciidae.

3. That the families Monacanthidae and Aracanidae be treated as subfamilies of the Balistidae

and Ostraciidae, respectively, and that the fSpinacanthinae of Tyler (1968) be removed from the

Triacanthodidae and placed as the sister group

of the Balistidae, being given equal rank (as

fSpinacanthidae).

4. That a superfamily Tetraodontoidea be

formed to contain the families fEoplectidae, Triodontidae, Tetraodontidae, Diodontidae, Molidae,

and—should fZignoichthys prove to be farther

along the gymnodont line than -fEoplectus, as

hinted by Tyler (1973) and tentatively preferred

here—the fZignoichthyidae.

5. That the family Canthigasteridae be reduced to subfamilial rank within the family

OR 2. Suborder Triacanthodoidei (1)

Family Triacanthodidae

Subfamily Triacanthodinae (1)

Subfamily? tCryptobalistinae (1)

Subfamily Hollardiinae (2)

Suborder Triacanthoidei (2)

Family Triacanthidae

Subfamily Triacanthinae

Subfamily tProtacanthinae

Suborder Tetraodontoidei (2)

OR 4. Family tEoplectidae (1)

Family Triodontidae (2)

Family Tetraodontidae (S)

Subfamily Tetraodontinae

Subfamily Canthigasterinae

Family Diodontidae (3)

Family Molidae 4)

Tetraodontidae,1 and that the fEoplectinae of

Tyler (1973) be transferred from the Triacanthodidae to the superfamily Tetraodontoidae, and

raised to familial rank, in keeping with its

phylogenetic position.

It seems unlikely, at this stage of our knowledge,

that the Tetraodontiformes is phylogenetically

equivalent to the Perciformes, and the sister group

of the former order (as alluded to in the text)

probably lies among the acanthurid-siganid-chaetodontid fishes. Since these latter groups are

presently classified in the order Perciformes, it

may well prove necessary to place them in the

tetraodontiforms when sufficient evidence to warrant such a change has been assembled. This,

however, must await further investigations.

1

 In this paper, the conventional view of the canthigasterids

forming the sister group of the tetraodontids has been followed. Recently, Tyler (ms) has demonstrated that the sister

group of Canthigaster consists of at least Carinotetrodon, and

quite possibly Monotreta and Cltelonodon as well. No representatives of the latter three genera were dissected for the

purposes of this study. Should Tyler's view prove to be correct, the subfamilial rank afforded to Canthigaster .above

would have to be rescinded, and the genus would become

completely incorporated within the Tetraodontidae. A detailed study of the generic interrelationships of this family

is badly needed.
100

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

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NUMBER 155 103

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List of Abbreviations

In figures where both muscles and bones are illustrated, muscle abbreviations are underscored

A 1.

A 2.

A 3.

A (a.

A.A.P

ABD.P.

ABD.S.

ACT.

AD.

ADD.P.

ADD.R.

ADD.S.

AD.OP.

A.D.P.

A.H.

A.M.L.

ANG.

A.P.P.

Ar

ARR.D.

ARR.V.

ART.

ASC.P.

A.S.P.

A.V.

A.V.P.

Ba

BBR.

BHY.

B.L.

BOC.

B.PT.

B.R.

B.V.

C.

Ca

CART.

CBR.

CHY.

CL.

COR.

COR.R.

C.P.

C.S.

C.T.

C.V.

DEN.

DEPR.

D.HHY.

Adductor mandibulae A 1, a, p, and y

Adductor mandibulae A 2, a, P. and y

Adductor mandibulae A 3

Adductor mandibulae A to

Adductor arcus palatini

Abductor profundus

Abductor superficial

Radial

Adductores

Adductor profundus

Adductor radialis

Adductor supcrficialis

Adductor operculi

Arrector dorsalis pelvicus

Adductor hyomandibulae

Articulo-maxilla ligament

Angular

adductor profundus pelvicus

Aracanidae

Arrector dorsalis

Arrector ventralis

Articular

Ascending process

Adductor superficialis pelvicus

Abdominal vertebra

Arrector ventralis pelvicus

Balistidae

Basibi anchial

Basihyal

Baudelot's ligament

Basioccipital

Basal pterygiophore

Branchiostegal ray

Buccal valve

Coelom

Canthigasteridae

Cartilage

Ceratobranchial

Anterohyal (=ceratohyal)

Clei thrum

Coracoid

Coracoradialis

Cartilagenous plug

Cut surface

Connective tissue

Caudal vertebra

Dentary

Depressores dorsales or anales

Dorsohyal (=dorsal hypohyal)

Di

D.L.

D.O.

D.RETR.

D.S.

EBR.

ECTO.

EHY.

EOC.

EP.

EPAX.

EPIP.

E.P.L.

EPOT.

EREC.

ETH.

F.

F.D.

F.D.S.

FOR.B.

F.R.

F.R.E.

F.V.

F.V.E.

F.V.I.

H.AB.

H.AD.

HBR.

H.L.

H.S.

HY.IN.

HYOM.

HYP.

IBR.

I.E.L.

IHY.

IMD.

INC.

INF A.

INF.M.

INF.P.

INT.

I.O.L.

IOP.

I.S.L.

L.A.P.

L.CUT.

L.EXT.

LIG.

Diodontidae

Dorsal lobe (of pelvis)

Dilatator operculi

Retractor dorsalis

Dorsal spine

Epibranchial

Ectopterygoid

Posterohyal (=epihyal)

Exoccipital

Epural

Epaxialis

Epipleural

Epihyal-pterygoid ligament

Epiotic

Erectores dorsales or anales

Ethmoid

Frontal

Flexor dorsalis

Flexor dorsalis superior

Blood vessel foramen

Fin ray

Fin ray element

Flexor ventralis

Flexor ventralis externus

Flexor ventralis inferior

Hyohyoidei abductores

Hyohyoidei adductores

Hypobranchial

Hypochordal longitudinalis

Haemal spine

Hyohyoideus inferioris

Hyomandibular

Hypural

Infrapharyngobranchial

Interopercle epihyal ligament

Interhyal

Intermandibularis

Inclinatores dorsales or anales

Infracarinalis anterior

Infracarinalis medius

Infracarinalis posterior

Interradialis

Interoperde-opercle ligament

Interopercle

Interopercle-subopercle ligament

Levator arcus palatini

Longitudinal cutaneous

Levatores externi

Ligament

104
NUMBE

R 155

LINT.

L.O.

MAX.

Me

M.E.L.

MESO.

META.

Ml

M.P.L.

N.S.

OBL.D.

OBL.I.

OBL.P.

OBL.S.

OBL.V.

O.FOR.

O.N.

OP.

OR.

Os

PAL.

PAS.

PCL.

PEL.

PF.

PHC.E.

PHC.I.

PM.

POP.

P.P.

P.P.L.

P.R.

PR.HY.

PROT.

PROX.

P.S.

PT.

PTS.

PTOT.

Q

R.A.P.

R.B.

Levatores interni

Leva tor operculi

Maxilla

Monacanthidae

Maxillo-ethmoid ligament

Mesopterygoid

Metapterygoid

Molidae

Maxillo premaxilla ligament

Neural spine

Obliquus dorsalis

Obliquus inferioris

Obliquus posterior

Obliquus superioris

Obliquus ventralis

Foramen for olfactory nerve

Olfactory nerve

Opercle

Olfactory rosette

Ostraciidae

Palatine

Parasphenoid

Postcleithra

Pelvis

Prefrontal

Pharyngoclavicularis externus

Pharyngoclavicularis internus

Premaxilla

Preopercle

Protractor pectoralis

Palatino-palatine ligament

Pelvic ray

Protractor hyoidei

Prootic

Proximalis

Pelvic spine

Posttemporal

Pterosphenoid

Pterotic

Quadrate

Retractor arcus palatini

Ramus buccalis VII

105

R.CAR.

R.COMM.

RECT. V.

R.I.

R.MD.

R.MX.

S.ANT.

S.B.

S.BL.a.

SCAP.

SCL.

S.M.

S.MED.

S.N.

s.o.

soc.

SOP.

SPIN.

S.POST.

SPOT.

STB.

STH.

SYM.

T.

Te

Ti

To

Tr

TR.

TR.C.

TR.CUT.

TR.D.

TR.V.

U.C.

U.HB.L.

UHY.

U.HYX.

VA.

V.F.R.

V.HHY.

VOM.

Rostral cartilage

Rectus coramunis

Rectus ventralis

Retractor interoperculi

Ramus mandibularis V

Ramus maxillaris V

Supracarinalis anterior

Swim bladder

Swim bladder "a"

Scapula

Supraclei thrum

Posterior swim bladder muscle

Supracarinalis medius

Supraneural

Sphincter oesophagi

Supraotcipital

Suboperde

Spinalis

Supracarinalis posterior

Sphenotic

Sternobranchialis

Sternohyoideus

Symplectic

Tendon of ...

Tetraodontidae

Triacanthidae

Triacanthodidae

Triodontidae

Levator pectoralis

Transversus caudalis

Transversus cutaneous

Transversus dorsalis

Transversus ventralis

Ural centrum

Urohyal-hypobranchial ligament

Urohyal

Urohyal-hypohyal ligament

Valvulus

Vestigial fin ray

Ventrohyal (=ventral hypohyal)

Vomer
FIGURE 1 Body outlines of representative triacanthodids: a,

Parahollardia (Hollardiinae); b, Halimochirurgns (Triacanthodinae). FIGURE 4. Body outlines of representative monacanthids:

a, Pervagor; b, Oxymonacanthus; c, Anacanthus.

FIGURE 5.—Body outline of a representative aracanid,

Aracanostracion.

FIGURE 2.—Body outline of a representative triacanthid,

Trixiphichthys.

FIGURE 3.—Body outline of a representative balistid, Batistes.

FICITKE 6.—Body outlines of representative ostraciids:

a, Acanthostracion; b, Lactoria.
NUMBER 155 107

FIGURE 7.—Body outline of Triodon macropterus.

a

FIGURE 8.—Body outlines of representative itetraodontids:

a, Lagocephalus; b, Arothron.

FIGURE 10.—Body outlines of representative diodontids:

a, Diodon; b, Chilomycterus.

FIGURE 9.—Body outline of a representative canthigasterid,

Canthigaster.

FIGURE 11.—Body outlines of representative molids: a, Mola;

b, Rumania.
108

To Ti B)aa We Ar Qs

i I V

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

Tr Te Ca Di Ml To Ti Ba Me Ar 0s Tr Te Ca Di Ml

1 J L

L

FICURE 12. Phylogenetic tree for section A 1 of the adductor FIGURE 13.—Phylogenetic tree for section A 2 of the adductor

mandibulae. (See "List of Abbreviations".) mandibulae.

To Ti Ba Me Ar 0s Tr Te Ca Oi ml

To Ti Ba Me Ar 0s Tr Te Ca Di Ml

j _J r 1

To Ti Ba Me Ar 0s Tr Te Ca Di Ml

To Ti Ba Me Ar 0s Tr Ta Ca Di Ml

FICURE 15.—Phylogenetic trees: a, the levator arcus palatini;

To Ti Ba Me Ar Oa TTrj T. Tee C Caa D Dii Ml b, the dilatator operculi.

To Ti 8a Me Ar Os Tr Te Ca Di Ml

FIGURE 14.—Phylogenetic trees: a, section A 3 of the adductor mandibulae; b, A oo of the adductor mandibulae; r

e, reinterpreted for section A to.

y

J L

a

To Ti Ba Me Ar 0s Tr Te Ca Di Ml v

FIGURE 16.—Phylogenetic trees: a, the levator operculi; b,

the adductor arcus palatini.
NUMBER 155 109

To Ti Ba We Ar Qs Tr Te Ca Di Ml To Ti Ba Me Ar 0s Tr Te Ca Di ml

Y

1 C

x y

V

To Ti Ba We Ar Qs Tr Te Ca Di Ml To Ti Ba We Ar Qs Tr Te Ca Di ml

I . Z—I

-I C

FICURE 17.—Phylogenetic trees: a, the retractor arcus pala- FICURE 18.—Phylogenetic trees: a, the adductor hyomandibtini; b, the adductor operculi. ulae; b, reinterpreted for the adductor hyomandibulae.

To Ti Ba We Ar Os Tr Te Ca Di ml To Ti Biea M e Ar Qs Tr Te Ca DD:i Ml

I Y M l

To Ti Ba We Ar Os Tr Te Ca Di Ml T o Ti Ba Me Ar 0s Tr Te Ca Di Ml

T

 ci T

J L

b

FICURE 19. Phylogenetic trees: a, the intennandibularis; b, FICITRE 20.—Phylogenetic trees: a, the hyohyoideus mfenons;

the valvulus. b, reinterpreted for the hyohyoideus inferiorit.
110 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

To Ti 8a Me Ar 0s Tr Te Ca Qi Ml To Ti Ba M,c Aj Qs Tr T.e C,a D.i M.1 v T V1

r T T

J L

To Ti Ba Me A;

Oi Ml

To Ti Ba Me Ar 0s Tr Te Ca Oi Ml

FIGURE 21. Phylogenetic trees: a, the hyohyoidei abductorcs;

b, the hyohyoidei adductores.

To Ti Ba Me Ar 0s Tr Te Ca Di Ml

To Ti Ba We Ar 0s Tr Te Ca Oi Ml

V

To Ti Ba Me Ar 0s Tr Te Ca Qi Ml

Y

FIGURE 22.—Phylogenetic trees: a, the sternohyoideus; b, the

sternobranchialis; c, alternative for the sternobranchialis.

To Ti Ba Me Ar 0s Tr Te Ca Oi Ml

To Ti Ba Me Ar 0s Tr Te Ca Di Ml

V Y

To Ti

•

FIGURE 23—Phylogenetic trees: a, the pharyngoclavicularis O

externus; b, the pharyngoclavicularis interims; c, the obliqui _

ventrales. FIGURE 24.—Phylogenetic trees: m, the transversi ventrales;

b, the recti ventrales.
To T i Ba l«lc Ar Os Tr Te Ca Di Ml

Y

To Ti Ba Me Ar Os Tr Te Ca Di Ml

To

T i Ba Me Ar Os Tr Te Ca Di Ml

V

ftr Qg T f

V

To Ti Ba Me Ar Os Tr Te Ca Oi Ml V

FIGURE 26.—Phylogenetic trees: a, the obliquu* dorsalis;

b, the transversi dorsales.

To Ti Ba Me Ar Os Tr Te Ca Di Ml

FIGURE 25.—Phylogenetic trees: a, the rectus communis; b,

the levatores externi. e, the levatores interni.

To Ti Ba Me Ar Os Tr Te Ca Di Ml

To Ti Ba Me Ar Os Tr Te Ca Di Ml

To Ti Ba Me Ar Os Tr Te Ca Di Ml

To Ti Ba Me Ar Os Tr Te Ca Di Ml

To Ti Ba Me Ar Os Tr Te Ca Di Ml

y y FIGURE 28.—Phylogenetic trees: a, the abductor superfidalis;

b, the abductor profundus; c, the adductor superfidalis.

-FIGURE 27.—Phylogenetic trees: a, the retractor dorsalis; b,

the adductores; c, the sphincter oesophagi.
112 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

To Ti 8a We Ar O.s Tr Te Ca Di ml

 T,° Ti Ba Me Ar Os Tr Te Ca Di mi

To TI 8a Me Ar 0,8 Tr T« Ca 01

To Ti Ba Me Ar Os Tr Te Ca 01 Ml

To T.i Ba Me Ar Os Tr Te Ca Di ml

V

To Ti Ba me Ar Os Tr Ti Ca Di Ml

1

JL

Tp Ti Ba Me Ap Qs Tr Te Ca Di ml To Ti Ba Me Ar Qa Tr Te Ca Di Ml \r r Os Tr Te Ca

FIGURE 29.—Phylogenetic trees: a, the adductor profundus; FIGURE 30.—Phylogenetic trees: a, the adductor radialis;

b, the arrector dorsalis; c, the coracoradialis; d, reinterpreted b, the protractor pectoralis; c, the levator pectoralis; d, reinfor the coracoradialis. terpreted for the levator pectoralis.
NUMBER 155 113

To Ti 3a Me Ar Os Tr Te Ca Di Ml

 T

v°

 TA 8» "I1

V 1 1 I I I I I I V V

Ar Os Tr Te Ca Di MJ

3 C

T:o Ti B8aa W Mie Ar Oa Tr Ta Ca Di Ml Too Ti Ba Pfc Ar Os Tr Te Ca Di Ml Ti Ba fflp Ar Os Tr Te Ca Oi ml

I I I i izz:

b

To Ti Ba Me Ar 9s Tr Te Ca Di Ml To Ti Ba We Ar Os Tr Te Ca Di HI

J L

FIGURE 31.—Phylogenetic trees: a, the arrector dorsalis pel- FIGURE 32.—Phylogenetic trees: a, the adductor superfidalis

vicus; b, the arrector ventralis pelvicus; c, reinterpreted for pelvicus; b, reinterpreted for the adductor superfidalis pelthe arrector ventralis pelvicus. vicus; c, the adductor profundus pelvicus.

To Ti Ba He Ar Os Tr Te Ca Di Ml

_l I

To Ti Ba He Ar Os Tr Te Ca Di Hi

t——1 '

FIGURE S3.—Phylogenetic trees: a, the indinatores donates;

b, reinterpreted for the indinatores dorsales.
To Ti Ba Me Ar Qs Tr Te Ca Di Ml To Ti 8a Me Ar Qs Tr Te Ca Oi Ml

J L

V V

To T i Ha flic Ar Os Tr Te Ca Oi ml

To Ti Ba We Ar Qs Tr TTee Ca Di ml Ca Di mi

I I I I

To Ti Ba Me Ar Qs Tr Te Ca Di ml

To Ti Ba me AT OS Tr Te Ca Di ml

V

To T i Ba me Ar Qs Tr Te Ca Di

r T

FICURF. 35.—Phylogcnctic trees: a, the indinatores anales;

b, the erectores anales; c, the depressores anales.

To Ti Ba Re Ar Os Tr Te Ca Di Ml

i J,

FIGURE 34.—Phylogenetic trees: a, the erectores dorsales; b,

reinterpreted for the erectores dorsales; c, the depressores

dorsales; d, reinterpreted for the depressores dorsales.

To T i Ba IDc Ar Os Tr Te Ca Di Ml

To T i 8a me Ar Os Tr Te Ca D i Ml

FIGURE 36.—Phylogenetic trees: a, the supracarinalis anterior;

b, reinterpreted for the supracarinalis anterior; c, the supracarinalis medius.
NUMBER 155 115

To TTi 8a We Ar Os Tr Te Ca Di Ml To Ti Ba Me Ar Os Tr Te Ca Oi Ml V V V

L

To Tl Ba Me Ar 09 Tr Te Ca Oi Ml

V VV V

To Ti Ba Me Ar Os Tr

TT

Ca 04 Ml

I

J I

To Ti Ba me Ar Os Tr Te Ca Di 1*11 To Ti Ba Me Ar Os Tr T

il

re Ca Oi Ml

To Ti 3a We Ar Os Tr Te Cn Oi ml

FIGURE 38.—Phylogenetic trees: a, the interradialis; b, the

hypochordal longitudinalis; c, the flexor dorsal is.

V

FIGURE 37.—Phylogenetic trees: a, the infracarinalis anterior;

b, reinterpreted for the infracarinalis anterior; c, the infracarinalis medius; d, reinterpreted for the infracarinalis

medius.

To Ti c Ar Qs Tr Ta Ca 0

To Ti Ba 15c Ar Qs Tr Te Ca Di ml

•I 1—L, i

3a Me Ar Os

FIGURE 39.—Phylogenetic trees: a, the flexor dorsalis superior; b, reinterpreted for the flexor dorsalis superior.
116 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

To Ti Ba Me Ar Os Tr Te Ca Di Ml To Ti Ba Me Ar Os Tr Ts Ca Di Ml

V

J L

v V

To Ti Ba Me Ar Os Tr Te Ca Oi Ml To Ti Ba Me Ap Q« Tr Tve Ca Oi Ml

I

I

I

To Ti Ba Me AT OS Tr Te Ca Oi M. To Ti Ba Me Ar Os Tr Te Ca Di Ml

FIGURE 41.—Phylogenctic trees: a, the transversus caudaliv.

"YY1 11 WW

FIGURE 40.—Phylogenetic trees: a, the flexor ventralis; b, the

flexor ventralis externus; c, the flexor ventralis inferior; d,

reinterpreted for the flexor ventralis inferior.
NUMBER 155 117

To Ti B,a Me Ar Oa Tr Te Ca Di Ml To Ti Ba We Ar Os Tr Te Ca 0 1 Ml

To Ti Ba Me Ar Os Tr Te Ca Di Ml

To Ti Ba Me Ar Os Tr Te Ca Di Ml

V

FIGURE 42.—Phylogenetic trees: a, the obliquus superioris;

6, the obliquus inferioris.

To Ti Ba Me Ar Os Tr Te Ca Di Ml

» . I

To Ti Ba Me Ar Os Tr Te Ca Di Ml

FIGURE 43.—Phylogenetic trees: a, the spinalis; b, reinterpreted for the spinalis; c, the transversus cutaneous; d, the

longitudinal cutaneous.
118 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 44.—A hypothesized phytogeny of the Tetraodontiformes, based on the analysis of those

muscles yielding phylogenetic information.

Solid black: The phylogeny included in the shaded area is as indicated in the phylogenetic

tree. If only two families are linked, the two families are sister groups.

Wavy lines: The contained families share a common ancestor, but further subdivision into

sister groups is not possible.

Oblique dashes: The common ancestor of the families linked by the wavy lines share* a

common ancestor with the families covered by this symbol.

Dots: As above, but the next lowest level of application.

Arrow: Used to link supposed sister groups where the hypothesized phylogeny is incorrect,

if confusion is otherwise likely.

A: An autapomorph condition, where this would otherwise affect the interpretation.

General: Where symbols extend halfway across the gap separating families and then cease

or change, it indicates that the family (ics) thus implicated should be linked with the

family (-ies) which is (are) elsewhere represented by the same half-symbol. It only occurs

where the hypothesized phylogeny is incorrect. The numerals in the right-hand margin

correspond to the text number used for that muscle. Where a muscle has been reinterpreted,

"a" and "b" are appended after the number. The numerals within the tree itself will be used

to designate branch points in the discussion. The letters "a" and "b" are used at points of

branching to clarify the lines in which the evidence applies.
40*

40k

4t

41 •

43 k

44

4tk

49*

60*

80k

TO
120

CRYPTOBALISTINAE

TRIACANTHIMAE

TO BALISTOIDS*,

PROTACANTHODINAE

.TRIACANTHODINAE

SPINACANTHINAE

FIGURE 45.—The phylogenetic tree of the basal tetraodontiforms. (Drawn from Tyler, 1968, fig. 6.)

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

CDEFGHJJ K

FIGURE 46.—Cladogram for taxa A-K.

FIGURE 47.—Phylogenetic tree of living and fossil tetraodontiforms. Daggers indicate fossil

groups; question mark emphasizes the tentative placement of the Cryptobalistinae as the sister

group of the Triacanthodinae; the digits 1 through 4 correspond to the hierarchical alternatives

in the classification on p. 99; outline of fossils from Tyler (ms).
NUMBER 155 121

c d

M\X

P\L

MEL.

P P l

ASC.P.

ran

PPL

PM.

MAX

DEN.

FIGURE 48.—Triacanthodes anomalus, ANSP 117493, 87 mm SL: a, medial view of right half of

jaw region; b, dorsal view of jaws (left palatine and maxilla removed); c, anterior view of left

maxilla; d, medial view of left maxilla. Triacanthus biaculeatus, ANSP 111536, 111 mm SL.:

e-f, left lateral view of snout region, -howing degree of upper jaw protrusion. (See abbreviations

list for explanation.)
122 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 49.—Triacanthodes anomalus, ANSP 11749S, 87 mm SL, left lateral view of superficial

anterior musculature.
NUMBER 155 123

SPOT

UHY.' HY. IN. '.R.COMM. >STH. MNF.A.

FIGURE 50.—Triacanthodes anomalus, ANSP 117493, 87 mm SL, left lateral view of the branchial

arch region. (Palatal arch and parts of the hyoid arch removed.)
V.HHY.

BHY

UHY.

RECTV. TRY . PHC.I.

L1G.

D.HHY.'

UHR

CM

CUR PHCE.

FIGURE 51.—Triacanthodes anomalus, ANSP 117493, 87 mm SL. ventral view of branchial arches,

urohyal displaced to left. (Left rectus communis and pharyngoclaviculares removed.)

'S.U

CBR

FIGURE 52.—Triacanthodes anomalus, ANSP 117493, 87 mm SL, left lateral view of dorsal

branchial arch region. (Levatores externi removed.)

tPlP

N S

D.RETR.

1CM.
NUMBER 155 125

CL.

F.R

ACT.

COR.

PEL

1 CM

FIGURE 53.—Triacanthodes anotnalus, ANSP 117493, 87 mm SL, medial view of left pectoral and

pelvic girdles and the associated musculature.

C.S.

FIGURE 54.—Triacanthodes anomalus, ANSP 117493, 87 mm SL, left lateral view of the spiny

dorsal fin. (Indinatores donates and the epaxialis removed.)
SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

I V

I K K

FIGURE 55.—Triacanthodes anomalus, ANSP 117495. 87 mm SL, left lateral view of the sixth

to ninth fin rays of: a, soft dorsal fin; b, anal fin. (Body muscles and first two inclinatores

removed.)

EPAX,

2BLJS.-

INFP

b

•SPOSI

INF.P,

SPOS I

INFP

nix iUF \ 1

IR.t

FICURE 56.—Triacanthodes anomalus, ANSP 117493, 87 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, after removal of body musculature; c, deep

layer of muscle.
NUMBER 155 127

PR. S. ANT

FIGURE 57.—Tydemania navigator is, ANSP 117532, 73 mm SL, left lateral view of superficial

anterior musculature.

a

FIGURE 58.—Macrorhamphosodes platycheilus, ANSP 117533, 88 mm SL: a, left lateral view

of superficial anterior musculature; b, mirror image of right lateral view of anterior snout region.
128 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

mm.

SPOT

L.EXT.

FICURE 59.—Macrorhamphosodes platycheilus, ANSP 117533, 88 mm SL, left lateral view of

branchial arch muscles (superficial).

a

OBL.l.

ABO.S

HY IN ' H.AB.' HAD.1 'STH

 N 1M£J L Rj.

FICURE m.—Halimochirurgus centriscoides, ANSP 117494, 114 mm SL: a, left lateral view

(slightly dorsal) of superficial anterior musculature; b, left lateral view of anterior snout, with

mouth fully open.
NUMBER 155 129

FIGURE 61.—Parahollardia lineata, ANSP 101031, 68 mm SL, left lateral view of superficial

musculature.
130 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

F.R

•\DD.R.

IOR

ll> K K

1CM.

FIGURE 62.—Parahollardia lineata, ANSP 101031, 68 mm SL, medial view of left pectoral girdle,

in the region of the radials. (Adductor superficial!* and profundus removed.)

1NF.A

FICURE 63.—Parahollardia lineata, ANSP 101031, 68 mm SL, dorsolateral view of left side of

pelvis. (Postdeithrum, obliquus inferioris, and adductor superficial pelvicus section serving

the pelvic spine removed.)
NUMBER 155 131

FIGURE 64.—Hollardia hollardi, ANSP 117491, 92 mm SL, left lateral view of superficial anterior

musculature.
132 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 65.—Hollardia hollardi, ANSP 117491, 92 mm SL, ventral view of superficial anterior

musculature.

FIGURE 66.—Trixiphichthys weberi, ANSP 117492, 122 mm SL, left lateral view of superficial

anterior musculature.

HYOM.

POP

PR.HVf

DEPR.
NUMBER 155 133

A. A. P.

IMS

a

1 CM

FIGURE 67.—Trixiphichthys weberi, ANSP 117492, 122 mm SL, posterolateral view of anterior

orbital region. (Adductor mandibulae complex removed.)

FIGURE 68.—Transverse sections progressing posteriorly of the left adductor mandibulae complex,

viewed from anterior: a, Hollardia hollardi, ANSP 117491, 53 mm SL; b, Triacanthus biaculeatus. ANSP 111556. HI mm SL.

\ I. A 1

IT

A2* .

R.MD.

CM.

b
134 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

TR.U.y L.EXT., PROTv PTS SPOT iPTOT

PJ.

FIGURE 69^—Trixiphichthys weberi, ANSP 117492, 122 mm SL, left lateral view of branchial

arch region. (The palatal and hyoid arches, and the abductor superfidalis removed.)
OBL.V. iRECT.V

RECT.V. TR.V

UHY

SPOT.

PTOTPROT.

LINT.-

PAS.

EBR.

IBRCBR.

FIGURE 70.—Trixiphichthys weberi, ANSP 117492, 122 mm SL, ventral view of branchial arches,

urohyal displaced to left. (Pharyngoclavicularis externus, right rectus communis, and part of

sternobranchialis removed.)

FIGURE 71.—Trixiphichthys weberi, ANSP 117492, 122 mm SL, left lateral view of dorsal

branchial arch region. (The levatores externi, the first arch, and ceratobranchials 3 and 4

removed.)

PHC.I.

1CM.
Lit.

I'll'K

•I RU

UPT.

SI'IS

FIGURE 72.—Trixiphichthys weberi, ANSP 117492, 122 mm SL, left lateral view of dorsal spine

region. (Epaxialis and inclinatores dorsales removed.)

FIGURE 73.—Trixiphichthys weberi, ANSP 117492, 122 mm

SL, medial view of left pectoral girdle. (Pelvis removed.)

FICURE 74.—Trixiphichthys weberi, ANSP 117492, 122 mm

SL, left lateral view of the sixth to eighth dorsal fin rays.

(Epaxialis and the sixth and seventh inclinatores dorsales

removed.)

INC

LKH
NUMBER 155 137

OBL.S.

b SPOST

INF.P.

FV.E

PROX/

HCURE 75.—Trixiphiehthys weberi, ANSP 117492, 122 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, deep musculature.

R.MD.

EREC

L.O

H I)

L A P

w.

HAD

STH. ABD.S/ ABD.P

INt

EPAX

OBL.S.

ARR.V.

OBL.I.

INF.M.

1CM.

FIGURE 76.—Triacanthw biaculeatus, ANSP 111536, HI mm SL, left lateral view of superficial

anterior musculature.
138 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

LIG.» A.S.P> INF.M. INC.

FICURE 77.—Tripodichthys oxycephalus, ANSP 89397, 82 mm SL, left lateral view of superficial

anterior musculature.
NUMBER 155 159

DEFR.

FIGURE IB^-Balisics vetula, ANSP 117535, 1S7 mm SL, left lateral view of superficial anterior

musculature.
FIGURE 79—Batistes vetula, ANSP 117535, 137 mm SL, left lateral view of snout region. (Most

of the adductor mandibulae complex removed.)

FIGURE 80.—Batistes vetula, ANSP 117535, 137 mm SL, left lateral view of head region. (Body

muscles, abductor superficial, lateral portion of the sternohyoideus, and the palatal arch

removed.)

S.MEI).

COR.' ARR.V.' 'ABDP '1NF.A. '1NF.M.
NUMBER 155 141

REcry TRY.

R.COMM/

OBL.V.1

Fir.iiRF 81.—Balistes vetula, ANSP 117535, 1S7 mm SL, ventral view of branchial arches. (Left

rectus communis, pharyngoclaviculares and right stemobranchialis removed^

SPOT

FIGURE 82.—Balistes vetula, ANSP 117535, 137 mm SL, left lateral view of dorsal branchial

arch region. (First branchial arch, palatal arch, pectoral girdle, and levatores externi removed.)
142

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

C.S

FIGURE 83.—Batistes vetula, ANSP 117555, 137 mm SL, medial

view of left pectoral girdle and associated muscles.

FIGURE 84.—Batistes vetula, ANSP 117535, 137 mm SL. left lateral view of pelvis, cut longitudinally slightly to the left of the midline, showing the muscles of the right side.
NUMBER 155 143

n. a

S.I'OSl

INF.P.

F.D.S.

H.L.

F.R.

INT.

1 CM.

b

N.S.

B.PT

SPOST.

B.PT. INF.P.

FIGURE 85.—Batistes vetula, ANSP 117535, 137 mm SL, left lateral view of caudal peduncle

region: a, superficial musculature; b, deep musculature.
144 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 86^-Balistapus undulatus, ANSP 117598, 83 mm SL, left lateral view of superficial

anterior musculature.
NUMBER 155 145

A Id..

Kit.

I CM.

Kit1CM.

FIGURE 87.—Transverse sections progressing posteriorly of the left adductor mandibulae complex,

viewed from anterior: a, Balistapus undulatus, ANSP 117598, 83 mm SL: b, Pervagor melanocephalus, ANSP 117500, 85 mm SL.
146 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 88.—Melichthys niger, ANSP 117515, 153 mm SL, left lateral view of superficial anterior

musculature.
NUMBER 155 147

FIGURE 89.—Rhinecanthus aculeatus, ANSP 117546, 159 mm SL, left lateral view of superficial

anterior musculature.
148 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

FIGURE 90—Odonus niger, ANSP 102779, 257 mm SL, left lateral view o( superficial anterior

musculature.
NUMBER 155 149

SfOT \ D S

TIL' rtL 'INFM

FIGURE 91.—Pervagor melanocephalus, ANSP 117512, 87 mm SL, left lateral view of superficial

anterior musculature.
150 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

ETH

Q.

IOP.' PRHYf

BPT.

EREC.

FIGURE 92.—Pervagor mehmocephalus, ANSP 117512, 87 mm SL, left lateral view of the

muscles of the cheek. (Most of the adductor mandibulae complex removed.)

deep

FIGURE 93.—Pervagor melanocephalus, ANSP 117512, 87 mm SL, medial view of right palatal

arch (posteroventral region). (Hyoid arch, except interhyal, removed.)

META

HYOM.

R.I.

POP

l.E.L
NUMBER 155 151

•ML

TR.V.

R.COMM/ STB.' BBR

FIGURE 94.—Pervagor melanocephalus, ANSP 117512, 87 mm SL, ventral view of branchial

arches. (Left rectus communis, sternobranchialis, and pharyngoclaviculares removed.)

- EPAX.

INF A.

FIGURE 95.—Pervagor melanocephalus, ANSP 117512. 87 mm SL, left lateral view of superficial

branchial arch musculature. (The palatal and hyoid arches removed.)
152 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

PRO I

P \ S

LINT

OBL.I).

1 UK

IliK

SCO I

DRtTR

IK I)

oiu r

_Ui

FIGURE %.—Pervagor melancephalus, ANSP 117512, 87 mm SL, dorsolateral view of the dorsal

branchial arch region. (The levatores exteri, first branchial arch, and ceratobranchial 2

removed.)
NUMBER 155 153

ADD.P

ADDS.

FICURE 97.—Pervagor melanoccphalus, ANSP 117512, 87 mm

SL, medial view of left pectoral girdle. (Postdeithrum,

removed.)

C.S.

A.V.P.' A.S.P. • FOR.B.'

1 CM.

FIGURE 98.—Pervagor melanocephalus, ANSP 117512, 87 mm

SL, left lateral view of pelvis, cut longitudinally slightly to

the left of the midline.
154

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

OBL.S.

OBL.I

FD.S.

H.L

1NF.P.-

1 CM

C.V

II.S

B.PT

IM.IV

F.DS.

FD.

FICURE 99.—Pervagor melanocephalus, ANSP 117512, 87 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, deep musculature.
TRCUT

FIGURE 100—Stephanolepis auratus, ANSP 117526, 64 mm SL, left lateral view of superficial

anterior musculature.

FIGURE 101.—Stephanolepis auratus, ANSP 117526, 64 mm SL, left lateral view of deep cheek

musculature. (A la. A la', and A 2 removed.)

H M).
156 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

A !«t?

EPAX

FIGURE 102.—Paramonacanthus barnardi, ANSP 117506, 78 mm SL, left lateral view of superficial anterior musculature.
NUMBER 155 157

EREC.

STH

INF.A

TR.CUT

1CM

S.MED.

FICURE 103—Chaetoderma spinosissimus, ANSP 117514, 42 mm SL, left lateral view of superficial anterior musculature.
158 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

EREC.

FIGURE 104.—Paraluteres prionurus, ANSP 106644, 57 mm SL, left lateral view of superficial

anterior musculature.
NUMBER 155 159

DEPR.

I ()

R.MD

INF.A.

FIGURE 105.—Cantherhines pardalis, ANSP 117530, 126 mm SL, left lateral view of superficial

anterior musculature.

INF.M.
FIGURE 106.—Oxymonacanthus lonprostris, ANSP 117496, 72 mm SL, left lateral view of

superficial anterior musculature.

Sill. 1 < INF.A. INF.M.'

FICURE 107.—Pseudalutarius nasicornis, ANSP 100830, 45 mm SL, left lateral view of superficial

anterior musculature.
EREC

A I *

R.MI)

FIGURE 108.—Aluterus monoceros, ANSP 117554, 345 mm SL, left lateral view of superficial

anterior musculature.

EPAX

wmac.

RJMX

RJHD

STH

INF.A

,1CM.

FIGURE 109.—Aluterus monoceros, ANSP 117554, S45 mm SL, left lateral view of the deeper

muscles in the head region.
162 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

RAP,

FIGURE 110.—Aluterus monoceros, ANSP 117554, 345 mm SL, left lateral view of the cheek.

(The adductor mandibulae complex removed.)

HBR. R.COMM.v STBj OBL.V. RECT.V. VCBR.

OBL.V.

RECT.V.

FICURE 111—Aluterus monoceros, ANSP 117554, 545 mm SL, ventral view of branchial arch

musculature. (Most of the muscles of the left side and the right rectus communis removed.)
NUMBER 155 163

TR.D.

1CM.

FIGURE 112.—Aluterus monoceros, ANSP 117554, 345 mm SL, left lateral view of dorsal branchial

arch musculature. (Palatal arch, pectoral girdle, and first infrapharyngobranchial removed.)

D.RETR.

L.

PCL

F.R

ACT.

FIGURE 113.—Aluterus monoceros, ANSP 117554, 345 mm SL, medial view of the left pectoral

girdle and associated muscles.
164 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

SMBD. ,ETAX.

FIGURE 114.—Anacanthus barbatus, ANSP 117516, 166 mm SL, left lateral view of superficial

anterior musculature.

CART.

PTS

PROT F .PTOT. /UNIi y S.ANT.

B.PT.

(SOP. 'OP. ' ARR.V,

 x ABD.P.' ABD.S.^ ADD.P.^OR. ^ PCL.

FIGURE 115.—Kentrocapros aculeatus, ANSP 117531, 91 mm SL, left lateral view of superficial

anterior musculature.

OBL.1
NUMBER 155 165

A 2f.

A2J.

RJ.

FIGURE 116.—Transverse sections progressing posteriorly of the left adductor mandibulae complex, viewed from anterior: a, Kentrocapros aculeatus, ANSP 117531, 91 mm SL; b, Ostracion

tuberculatus, ANSP 117542, 102 mm SL.
FIGURE 117. Kentrocapros aculratus, ANSP 117531, 91 mm SL, dorsolateral view of the deep

muscles of the cheek.

FIGURE 118.—Kentrocapros aculeatus, ANSP 117531, 91 mm SL, ventral view of superficial

anterior musculature.

H.AD STSTB ' CL.' ABD.S
NUMBER 155 167

FICURE 119.—Kentrocapros aculeatus, ANSP 117531, 91 mm SL, left lateral view of superficial

branchial arch musculature.
168

UHY

U.HY.L.

RECT.V.

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

CM.

PHC£.

R.COMM. 9J.

SSL

STB.' OBLV.

1CM.

FIGURE 120.—Kentrocapros acuteatus, ANSP 117531, 91 mm SL, ventral view of branchial arch

musculature.

PAS PROT. < AD.OP. yA.H.

FIGURE 121.—Kentrocapros aculeaius, ANSP 117531, 91 mm SL, left lateral view of dorsal

branchial arch musculature. (The levatores externi, interni, and the first arch removed.)
NUMBER 155 169

SJOST

FICIRE 122.—Kentrocapros aculeatus, ANSP 117531, 91 mm SL, left lateral view of dorsal and

anal fin musculature.

ADDS.

•ARR.D.

COftJt.

COR.

CL.

R/.

FICURE 123.—Kentrocapros aculeatus, ANSP 117531, 91 mm SL, medial view of left pectoral

girdle and associated musculature, from somewhat posterodorsally.
170 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

UtX

IBX

F.VJ.

FIGURE 124—Kentrocapros aculeatus, ANSP 117531, 91 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, deep musculature.

OBLJ.v S. ANT.t EPAX\ INC

UINT.

PR.HY.

INT

OBLS.

I)EPR

X10.

FIGURE 125.—Capropygia unistriata, ANSP 109574, 67 mm SL, left lateral view of superficial

musculature.
FU.

FICUKE 126.—Ostracion tuberculatus, ANSP 117542, 102 mm SL, left lateral view of superficial

anterior musculature.

FIGURE 127.—Ostracion tuberculatus, ANSP 117542, 102 mm SL, left lateral view (slightly

dorsally) of the deep check musculature.

ETH.

VOM.

StLL

ART.

ANG/ IOP POP

I CM.
172

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

IHY.

FIGURE 128.—Ostracion tuberculatus, ANSP 117542, 102 mm SL, dorsolatcral view of snout

region after removal of the adductor mandibulae complex.

C.S.

PROT

FIGURE 129.—Ostracion tuberculatus, ANSP 117542, 102 mm SL, left lateral view of superficial

branchial arch musculature.
NUMBER 155 173

UHY.

U.HHY.

U.HY.L

K.tOMM.

CBR.

HBR OBL.V.

1CM.

FICURE ISO—Ostracion tuberculatus, ANSP 117542. 102 mm SL, ventral view of the branchial

arch musculature. (Left rectus communis removed.)

PAS

CBR.

1CM.

LINT.

OBLP

FICURE 131.—Octradon tuberculatus, ANSP 117542, 102 mm SL, dorsolateral view of dorsal

branchial arch musculature. (Levatores externi removed.)
174

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

K L

FR

COR.

ARRD.

CL

FIGURE 132.—Ostracion tuberculatus, ANSP 117542, 102 mm SL, posteromedial view of left

pectoral girdle and associated musculature.

FR

S.POST.

c.v.

INFP.

B.PT.

SJjJL*.

ERECT DEPR/ >F.R.

FICURE 133.—Ostracion tuberculatus, ANSP 117542, 10Z mm SL, lett lateral view oi aeep Doay

musculature.
NUMBER 15S 175

b

r.yj. r.vx

FICURE 134.—Ostracion tuberculatus, ANSP 117542, 102 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, deep musculature.

FICURE 135.—Lac tor ia cornuta, ANSP 117539, 176 mm SL, left lateral view of superficial

anterior musculature.

L.A.T.

DO.

L.O

A2«C

A2P.

A 3 .

R.MD

PR.HY.

EPAX.

ARR.V.

ABD.S.

ABU.P.

OBL.I.

H.AD/ 'HY.IN. H.AB. STH.
EPAX.

FICURE 156.—Tetrosomus

concatenate, ANSP

117555. 196 mm SL, left

lateral view of superficial

anterior musculature.

L A *

DO

LO

\ i

R.MD

AX.

A 3

FIGURE 1S7<—Aeanthostracion quadricornis, ANSP

98848, 126 mm SL, left

lateral view of superficial

anterior musculature.

OBL.1.

H.AB.
NUMBER 155 177

FIGURE 138.—Triodon macropterus, ANSP 103902, 270 mm SL, left lateral view of superficial

anterior musculature.
178

A 3 .

SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

A 1.

R.MD.

A 3 .

I CM.

b

113639, 124 mm SL.
NUMBER 155 179

FICURE 140—Triodon macropterus, ANSP 10S902, 270 mm SL, left lateral view of the deep

muscles of the cheek.

MR. HBR

C.S.

UHY.

U.HY.L.

RCOMV

RECTV <MM-V. RECTV TRV, ^

FIGURE 141.—Triodon macropterus, ANSP 103902, 270 mm SL, ventral view of branchial arch

musculature. (Left rectus communis and pharyngoclaviculares removed.)
180 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

PROT

LEXT

LJNT.

(UK

I CM.

FIGURE 142.—Triodon macropterus, ANSP 103902, 270 mm SL, left lateral view of dorsal

branchial arch region. (Most of the levatores extern! removed.)

B.L.

ADD.S.

ARR.P.

CL.

PCL.

COR.

FIGURE 143—Triodon macropterus, ANSP 103902, 270 mm SL, medial view of left pectoral

girdle and associated musculature.
a

JNC

FICURE 144.—Triodon macropterus, ANSP 103902, 270 mm SL, left lateral view of dorsal and

anal fin musculature.

FIGURE 145.—Triodon macropterus, ANSP 103902, 270 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, aha removal of the aponeurosis; c, deep

musculature.

F.VJ./ 'r.v.
i. ANT.

DEN

mru

FIGURE 146.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, left lateral view of superficial

anterior musculature.

FIGURE 147.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, left lateral view of cheek

musculature after the removal of A 1.

ETH

-PTOT.

I CM
NUMBER 155

183

PAL

1CM.

SYM.

FICURE 148.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, left lateral view of the deep

muscles of the cheek.

I CM.

POP.

FIGURE 149.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, medial view of articulation

region of left lower jaw.
184 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

SfOT.-

PROT

RECT.V.

c.s.

CHY

H.Afc

I CM

FIGURE 150.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, left lateral view of superficial

branchial and hyoid arch musculature.

JUL

FIGURE 151.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, ventral view of branchial arch

musculature.

MLV . PHC.E.

LIG

mm

R.COMM.

PHC.I.

TRY.

CBR.
PROT

II1K

DRLTR.

TR.D

FIGURE 152.—Lagocephalus lunaris, ANSP 113639, 124 mm SL, left lateral view of dorsal

branchial arch musculature.

FIGURE 153 Lagocephalus lunaris, ANSP 113639, 124 mm SL, medial view of left pectoral girdle

and associated musculature.

ADOS. CL

COR.R.
186 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

EREC> Dl I1

B.PT

1NF.MINC.

INC.

1CM.

FICURE 154.—Lagocephaltis lunaris, ANSP 113639, 124 mm SL, left lateral view of dorsal and

anal fin musculature.

a b

S.POST.v N.S.'

FICURE 155—Lagocephalus lunaris, ANSP 113639, 124 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, deep musculature.
NUMBER 155 187

D.O.V L.O.V C.S PP. TR.

K\p.

A l«t

A2W.

PR.HY

H.AB.

EPAX.

OBL.l

INF.M.

FICURE 156.—Amblyrhynchotes honckenii, ANSP 117547, 106 mm SL, left lateral view of

superficial anterior musculature.

L-O.v C

A2i.'

PR.HY. VAB. 'HAD. STH. ^INF.A. NL.CUT .P. WBD.S.

 XARR.V.

FICURE 157. Colomesus psittacus, ANSP 98887, 117 mm SL, left lateral view of superficial

anterior musculature.
188 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

EREC.v DEPR.

LO

LA*.

EPAX.

A Id.

FR.HY

H.AB.

I CM.

FKU U 158.—XtnopUnu tutritus, ANSP 117495. 102 mm SL, left lateral view of superficial

anterior musculature.

DO

LO

A If

A U .

•AX.

ABOT. ABD.S.

 XAR».V.

1=

FIGURE 159^-ilrortron irnmacufato, ANSP 117528, 68 mm SL, left lateral view of superficial

musculature. ("?INCH implies that the identification of these fibers as part of the incUnator

(analis) system is tentative.)
NUMBER 155 189

C.S» P.P.

\ : »

M M . I' Vlili s

 N \KK \

FIGURE 160.—Tetraodon schoutedeni, ANSP 117501, 62 mm SL, left lateral view of superficial

anterior musculature. ("?INC", as for Figure 159.)

0-

PR.HY

rH.AD. 'STH. 'ARR.V. ^ ABDA V OBL.I. VlNFM.

FICUIUE 161.—Ctmthigaster margaritatus, ANSP 117517, 52 mm SL, left lateral view of superficial

anterior musculature.
190 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

A.A.P.. PF

ETH

FKun 182.—Cmthiputer mmrgmritatm, ANSP 117517, 52 mm SL, left lateral view of deep

muscles of the cheek.

FKUKB lte—C*nthig*sUr mmrgaritatus, ANSP 117517, 52 mm SL, left lateral view of superficial

branchial arch musculature.

PTS

SPOT.'

PROT

c.s.

HBK

R.COM.M.

STH.

I CM.
NUMBER 155 191

DRETR

I CM.

FICURE 164.—Canthigaster margaritatus, ANSP 117517. 52 mm FICUKE 165.—Canthigaster nutrgaritatus, ANSP 117517, 52 mm

SL, ventral view of branchial arch musculature. SL, left lateral view of dorsal branchial arch region. (The first

infrapharyngobranchial, epibranchials 1 and 2, ceratobranchials 1-5, and the levatores extern! removed.)

S.ANT., BPT EREC, i DEPR

soc

INC

INF.M.

Fir.iRF 166.—Canthigaster margaritatus, ANSP 117517, 52 mm SL, left lateral view of dorsal

and anal fin musculature.
192 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

EPAX.

OBI..S.

b

N.S/

F.R. C.V

.INT. H.S

OBL.I. 1NF.P. 'F.V.I.

I CM.

FIGURE 167.—Canthigaster margaritatus, ANSP 117517, 52 mm SL, left lateral view of caudal

peduncle region: a, superficial musculature; b, deep musculature.

FIGURE 168.—Canthigaster valentini, ANSP 117534, 45 mm SL, left lateral view of superficial

anterior musculature.

s. ANT.

A IP.

EREC.

OBL.S.

INC

STH. IABD.P. ^ABD.S.

 XARR.V. ^ OBL.I. MNF.M.

1 CM.
NUMBER 155 19S

PTOT. v OP

SCL. ,CL. ARR.V. PCL. yETAX.

INC

•JNC

PR.HY/ H.AD.' B.R.' HAR' 'ABD.S.

FICURE 169—Diodon hystrix, NMC 68-997, 77 mm SL, left lateral view of superficial anterior

musculature.

DEN.

SPOT.

LAP.

PTOT.

HYOM.

PROT

FIGURE 170.—Diodon hystrix, NMC 68-997, 77 mm SL, left lateral view of the deep muscles of

the cheek.
194 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

CL.

PHC.I.

V.HHY.

STH.

I CM.

FICURE 171.—Diodon hystrix, NMC 6S-997, 77 mm SL, left lateral view of superficial branchial

arch musculature.

CBR.

HBR

BBR

RECT.V c.s.

1 CM.

FICURE 172.—Diodon hystrix, NMC 6&-997, 77 mm SL, ventral view of branchial arch

musculature.
NUMBER 155 195

soc. EOC N.S. ,A.V.

EffOT.

tBR'

FIGURE 173.—Diodon hystrix, NMC 68-997, 77 mm SL, left lateral view of dorsal branchial

arch musculature. (Epibranchials 1 and 2, ceratobranchials 1-3, and the levatores externi

removed.)

PCL.

F.R.

ACT.

FIGURE 174.—Diodon hystrix, NMC 68-997, 77 mm SL, medial view of left pectoral girdle and

associated musculature.
196 SMITHSONIAN CONTRIBUTIONS TO ZOOLOGY

a

EEA&

F.VJ.

FIGURE 175.—Diodon hystrix, NMC 68-997, 77 mm SL, left lateral view of caudal peduncle

region: a, superficial musculature; b, deep musculature.

P.P., TR

A \JL

H.AD/ H.AB/ 'ABDS

 N ABD P **OBLI. INF.M

FIGURE 176.—Chilomyctertu orbicularis, ANSP 117510, 80 mm SL, left lateral view of superficial

anterior musculature.
A2«C

A 1*.

HAD \ABDP \\BDS

FIGURE 177.—Chilomycterus schoepfi, ANSP 117518, 138 mm SL, left lateral view of superficial

anterior musculature.

FIGURE 178.—Mola mola, BM(NH) 1938.623.38, 287 mm SL, left lateral view of superficial

anterior musculature.

EPOT C.S. (EREC.+DEPR.)

H.AR>

HAD.

SIHf PHC.E.

\=i
PAL

PAS

R.MD

IOP

FICURE 179 Mola mola, BM (NH) 19S8.6.2S.S8, 287 mm SL, left lateral view of the deep

muscles of the cheek.

FICURE 180 Mola mola, BM (NH) 1938.62S.S8, 287 mm SL, left lateral view of superficial

branchial arch musculature.

SPOT

V.HHY

CL.

SDL
NUMBER 155 199

CART

HBK

IJISK

cs

D.HHY.

RECT.V.

CBR.

S.0,

TR.V.

PMCJ.

OBL.V.

PHC.E.

R.COMM.

FIGURE 181.—Mola mola, BM(NH) 19S8.623.S8, 287 mm SL, ventral view of branchial arch

musculature.

PAS

IBR.

EBR.'

CBR

FIGURE 182 Mola mola, BM (NH) 1938.62S.38, 287 mm SL, left lateral view of dorsal branchial

arch musculature. (Epibranchials 1 and 2, ceratobranchials 1-3, and the levatores externi and

interni removed.)
ADD.P.

FR

CL.

COR.

AC I

FIGURE 183—Afofo mola, BM (NH) 1938.6.23.38, 287 mm SL, medial view of left pectoral

girdle and associated musculature.

EREC. + DEPJL

FRF.r +DEPR

BPT

EPAX.

CART.
NUMBER 155 201

EREC+DEPR

EREC+DEPR.

A2«L

nunr

OBL.I.' AMDS. ^AMKF. »AWLV.

FIGURE 185.—Ranzania laevis, ANSP 106723, 93 mm SL, left lateral view of superficial anterior

musculature.

FICURE 184-—Mola mola, BM(NH) 1938.6.23.38, 287 mm SL, left lateral view of dorsal, anal, and caudal fin musculature.

•ft U.S. GOVERNMENT PRINTING OFFICEl 1974 1974 516^223/23



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