Trepostomatous Bryozoa 

of the Hamilton Group of

By RICHARD S. BOARDMAN

GEOLOGICAL SURVEY PROFESSIONAL PAPER 340

Geology, evolution, and descriptions, 

based on a revised method of 

classification

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1960
UNITED STATES DEPARTMENT OF THE INTERIOR 

FRED A. SEATON, Secretary

GEOLOGICAL SURVEY 

Thomas B. Nolan, Director

For sale by the Superintendent of Documents, U.S. Government Printing OfBce 

Washington 25, D.C. - Price ?1.25 (paper cover)
CONTENTS

Abstract._-_-________-_-______-___---_---___---_-__

Introduction _______________________________________

Stratigraphy __________--______-_-_---_-----------__

Marcellus and Skaneateles formations.-___________

Ludlowville shale.____---__-_-------_-----------

Moscow shale.___--____----_---------_-------__

Paleoecology _-___--___------_-__---------_-------_-

Bryozoa and environments.----------------------

Lithofacies and bryozoan faunas of the Hamilton 

group-. . ____________________________________

Time and stratigraphic relations.---------------------

Evolution ____-_______--________----------_--._-__-_

Time and space relations of lineages__------_--__--

Morphologic trends of lineages.-.__-___-___-_-__-_

Comparison of Trepostomata from Hamilton and

Traverse groups._--_--____--------__---------

Register of localities_______________________________

Glossary.._________________________________________

Morphology and taxonomy._-._____-_--------_-__--.

Early history of the study of the Order Trepostomata

Page 

1 

1 

3 

3 

3

7

8

9

11

12

13

15

15

18

21

23

23

Page 

Morphology and taxonomy Continued

Wall structure and taxonomy_______--___.---_-__ 25

Previous work..____________________________ 25

Wall structure and taxonomy in the Hamilton

Trepostomata- - _---_------------__------_ 26

Tentative groupings of genera from Hamilton

and Traverse groups.._---_------______.-- 29

Stereotoechid wall structure.__.--_---____ 30

Leioclemid wall structure_---_------_-___ 30

Trachytoechid wall structure.------------ 31

Leptotrypellid wall structure _____________ 32

Atactotoechid wall structure__-_-____.___ 32

Zoarial growth and taxonomy. ___________________ 33

Distribution of morphologic characters within

Hamilton zoaria.--_--------------___-____ 33

Zoarial variation and species criteria. ____---__ 35

Mode of ramose zoarial growth.___________________ 38

Systematic descriptions...--------------------------- 40

Literature cited'______-__---_--------_---__--____-__- 82

Index __-..____.__.._____.__-----_-___---_____--.__ 85

ILLUSTRATIONS

[Plates follow index]

PLATE 1. Stereotoechus, Calacanthopora, and Eridotrypella.

2. Dyoidophragma.

3, 4. Leioclema.

5. Trachytoechus.

6-14. Leptoirypella.

15. Leptotrypella, Polycylindricus.

16. Polycylindricus.

17-20. Atactotoechus.

21, 22. Loxophragma.

FIGURE 1. Outline map of New York showing area 

studied _______________________________

2. Members of the Ludlowville and Moscow 

formations arranged relative to their inferred time and geographic position ______

3. Stratigraphic distribution of the trepostomatous Bryozoa of the Hamilton group of New 

York..--.____________________________

4. Time-space diagram of the genus Leptotrypella in the Hamilton group of New York, _

5. Time-space diagram of the genus Atactotoechus in the Hamilton group of New York. _

6. Map showing outcrop of Hamilton group, 

and collecting localities.-_----___--_-__.

7. Diagrams illustrating standard measurements. -------_-_-----_---------._____

8. Diagrammatic tangential and longitudinal 

sections of a zooecium illustrating the laminated structure of the skeleton._________

9. Diagram of stereotoechid wall structure.--.

10. Diagram of leioclemid wall structure.--.-.-

11. Diagram of trachytoechid wall structure....

12. Diagram of leptotrypellid wall structure_-__

13. Diagram of atactotoechid wall structure....

14. Graph of measurements along length of zoarium of holotype of Leptotrypella asterica..

Page

13

14

19

22

27

30

31

31

32

32

34

Page 

FIGURE 15. Graph of measurements along length of

zoarium of Leptotrypella multitecta....-..- 34

16. Peripheral scatter diagram of Atactotoechus 

cartus cartus of number of diaphragms 

against width of ephebic zone.____.__'_-_ 37

17. Peripheral scatter diagram of Atactotoechus 

cartus cartus of number of diaphragms 

against axial ratio.__--__-_------_--_--- 37

18. Peripheral scatter diagram of Atactotoechus 

cartus cartus of number of diaphragms 

against zooecial surface angle.----------- 37

19. Peripheral scatter diagram of Atactotoechus 

cartus cartus of diameter of neanic zone 

against diameter of zoarium._.__________ 37

20. Idealized diagram of ramose bryozoan illustrating mode of growth.________________ 39

21. Graph of measurements along length of zoarium of holotype of Leptotrypella multitecta. 40

22. Diagrammatic longitudinal section of Dyoidophragma polymorphum illustrating the laminated structure of the skeleton._________ 42

23. Chart of possible phylogenetic relationships 

of some of the species of the genus Leptoirypella- -_____-_--_----_---__--__--__-__ 52

24. Peripheral scatter diagram of the Leptotrypella mesostena-multitecta lineage.---____- 54

25. Possible phylogenetic relationships of the 

New York species of the genus Atactotoechus _-_--_-------_----__---__-----_ 70

26. Peripheral scatter diagram of some of the

species of Atactotoechus. ________________ 71

27. Peripheral scatter diagram cf the New York

species of Loxophragma................. 79

in
TREPOSTOMATOUS BRYOZOA OF THE HAMILTON GROUP OF NEW YORK STATE

By RICHARD S. BOARDMAN *

ABSTRACT

The trepostomatons Bryozoa known from the Middle Devonian Hainilton group of New York represent 26 species and 

two subspecies belonging to 10 genera and 1 subgenus. Two 

genera, Polycylitulricus and Loxophragma; the subgenus, 

Lcptotrypella (Pycnobasis) ; and 19 species and the 2 subspecies are new.

In the area of study from Lake Erie to Owasco Lake, 

Trepostomata are known only from the Ludlowville and Moscow formations. Some species have a restricted stratigraphic 

distribution. In the Ludlowville shale, four species are restricted to the Centerfield limestone member, 1 subspecies to 

the Ledyard member of Cooper (1930), three species to the 

Wanakah member as used by Buehler and Tesmer (in press), 

and 1 species is restricted to the King Ferry shale member 

of Cooper (1930). In the Moscow shale, 1 species and 1 subspecies are restricted to the Kashong member of Cooper (1930) 

and 4 species are restricated to the uppermost Windom member.

The Hamilton rocks of western and central New York consist largely of calcareous inudstone, shale, and limestone. 

Five rock types are represented, and these are closely correlated with the distribution of faunas. Trepostomata are 

abundant in the calcareous inudstone facies, sparse in the siltstone and coral-bearing limestone, and were not found in the 

dark shale and sandstone. Application of Stach's findings on 

Recent Bryozoa to the Hamilton species suggests that growth 

habit was controlled largely by the amount of agitation in 

the water, "unstable" species developing ramose colonies in 

quiet water and incrusting colonies in agitated water. The 

predominantly incrusting colonies and bioclastic matrix in 

the coral-bearing limestone facies suggest agitated waters; 

the predominantly ramose colonies preserved as complete 

zoaria in the calcareous mudstone facies suggest quieter 

waters.

The defined members of the Ludlowville and Moscow formations are considered, on the basis of the distribution of the 

bryozoan species,, to be essentially coeval, and phylogenetic 

lineages are inferred in three genera. A general increase in 

size of zoaria is demonstrated in the lineages of the three 

genera.

The present study indicates that amalgamate and intergrate 

wall structures in tangential sections are not reliable subordinal criteria, primarily because occurrence of amalgamate 

or integrate walls is not always constant within a species or 

genus. Longitudinal sections demonstrate that either an 

amalgamate or an integrate appearance can be produced by 

variations in either one of two wall structures now tentatively 

considered to be fundamentally different and taxonomically

1 Now with the Smithsonian Institution, Washington, D.C.

important. Hamilton genera do not 'fit into the present family 

classification, partly due to the lack of recognizable "primary',' 

and "secondary" parts of zooecial walls. A tentative grouping of-the Middle Devonian genera is based on the configuration of the laminae in the zooecial walls as seen .in both 

longitudinal and tangential sections. One tentative subordinal 

group includes genera displaying stereotoechid, leioclemid, 

trachytoechid, -and leptotrypellid wall structures, all defined 

in this paper. The other, group includes the genera showing 

atactotoechid wall structure, also defined. The wall structure 

for each of the Hamilton genera, is described in detail and 

previously described species are reassigned where necessary.

The nearly complete ramose zoaria collected in the Hamilton 

group furnished material for study of morphologic variation 

within a colony. The amount of variation indicates that 

"species" could be and probably have been .differentiated on 

characters commonly occurring in a single zoarium. Intrazoarial variation of characters falls into two natural groups: 

that controlled by growth stages (ontogeny), and that largely 

independent of ontogeny. To evaluate and- make usable 

characters affected by ontogeny, growth stages are arbitrarily 

defined by numbers of diaphragms in the zooecia. Measurements of the other ontogenetic characters, primarily width of 

ephebic zone and axial ratio, are recorded for each of these 

growth stages and presented either in scatter diagrams or 

tables. After study of complete trepostomatous zoaria of the 

Hamilton group, it is evident that if a reasonable number of 

disassociated fragments of trepostomes from the average collection is studied, an adequate approximation of growth stages 

can be obtained and more realistic species concepts established.

The nearly complete ramose zoaria also provide information 

on the nature of growth in branching colonies. A'.proposed 

growth hypothesis is based on cyclic growth and resorption. 

Thick zooecial walls were periodically formed around the ends 

of the branches, as shown by their presence in 80 percent of 

the sectioned growing tips. The thick zooecial walls were 

partly resorbed in the growing tip region and active thinwalled growth followed, extending the neanic zones and 

branch lengths distally. The formation of new thick-walled 

zones around the tips completed the cycle. Proximal to the 

growing tips, the zooecia assumed permanent positions opening 

along the sides of the branches. Here growth was relatively 

constant with no sign of resorption and progressively older 

growth stages occur toward the bases of zoaria.

INTRODUCTION

The Hamilton group of New York State has been 

considered one of the classic Middle Devonian sections of the world since the early work of James Hall

1
TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

with the New York Geological Survey. The Hamilton fauna is noted for its abundance, diversity, and 

excellent preservation. The bryozoan element of the 

fauna includes representatives of all four Paleozoic 

orders and is especially distinguished by the common 

occurrence of essentially complete zoaria.

This paper deals with one of the four Paleozoic 

orders of the Bryozoa, the Trepostomata. The purpose of the study is to review and re-evaluate the morphology and its bearing on taxonomy and to describe 

the fauna and investigate its possible stratigraphic 

value.

The fieldwork was done during the summer of 1952 

and 1953. The material studied includes collections 

made available by the U.S. National Museum in addition to those collected by the author for the U.S. 

Geological Survey. Within the Hamilton group, the 

Trepostomata were found only in the Ludlowville and 

Moscow formations of the Tioughnioga stage of 

Cooper and others (1942) and were geographically 

limited to the region between Lake Erie and Cayuga 

Lake, with the exception of a few rare occurrences 

farther east in New York (fig. 1).

Previous work on the Bryozoa of New York State 

was done almost entirely by James Hall and his colleagues. Hall did not use thin sections in his work 

and most of his species will not be recognizable until 

the types are sectioned. Few of the species Hall 

described are of the Trepostomata, as this order shows

LIST OF QUADRANGLES

1 A, Buffalo B, Eden

2 Depew

3 Attica

4 Batavia

5 Caledonia

6 Honeoye

7 Canandaigua-Phelps

8 A, Geneva B, Ovid

9 A,Auburn B, Genoa

FIGURE 1. Map of New York State showing the area of the outcropping 

belt of the Hamilton group and outlines of the Geological Survey quadrangle maps covering the area studied.

little differentiation externally. Most of Hall's work 

is concerned with the Cryptostomata and Cyclostomata 

and was published between 1873 and 1891. His most 

comprehensive work on the Bryozoa was published 

in 1887 (Hall and Simpson).

A few other trepostomatous Bryozoa from New 

York are described in papers dealing largely with 

other areas or with general faunal studies. Ulrich 

(1890, p. 416, pi. 45, figs. 5-5d) described Dekayia 

devonica, some of the cotypes coming from the 

Eighteen Mile Creek section, Erie County, New York 

(present report, p. 67). Grabau (1899, p. 137, fig. 

22) described Monotrypa amplectens from the Averys 

Creek section, Erie County, New York, in a general 

faunal study of the Hamilton group of the Eighteen 

Mile Creek section (present report, p. 60). Ulrich 

and Bassler (1904, p. 39, pi. 11, figs. 10-12) described 

Leioclema monroei from a locality near Bethany, N.Y. 

(present report, p. 45).

The known work on the Trepostomata of the Hamilton of New York is covered in this short summary. 

The large proportion of new species described in this 

paper reflects the lack of work done on the order.

The only major study of Trepostomata of Hamilton 

age outside of New York State is that of Duncan 

(1939) on the fauna of the Traverse group of Michigan. Eleven new genera were erected, 6 of which 

occur in New York. Other authors described one to 

several species of Traverse Trepostomata without 

attempting a complete study (Winchell, 1866; Rominger, 1866; Ulrich, 1890; and Bassler, 1911b). Scattered species are also described from strata of Hamilton age in Ontario by Nicholson (1874a, 1874b) and 

Fritz (1930). Bassler (1911b) described several species from the Devonian of Wisconsin, and Ulrich and 

Bassler (1913b) described a single species from the 

Romney shale of Maryland. Single species were described from Hamilton equivalents in Iowa (White, 

1876) and Ohio (Stewart, 1927).

This work was done under the guidance of Helen 

Duncan, of the U.S. Geological Survey. U. S. National Museum specimens included in the study were 

collected by G. A. Cooper, A. R. Loeblich, Jr., and 

I. G. Reimann. Collecting localities were suggested 

by the late R. R, Hibbard, of Buffalo, N.Y., J. W. 

Wells, G. A. Cooper, and I. G. Reimann. James Hall's 

type specimens were generously made available for 

sectioning and study by D. W. Fisher, C. F. Kilfoyle, 

and N. D. Newell. Type thin sections of Traverse 

species were loaned to the writer by G. M. Ehlers. 

Many helpful suggestions were made by G. A. Cooper, 

W. A. Oliver, Jr., F. H. T. Rhodes, and H. R. 

Wanless.
STRATIGRAPHY

STRATIGRAPHY

The Hamilton group of New York is part of the 

standard North American Devonian column and is 

correlated with the Eifelian and most of the Givetian 

of Europe (Cooper, and others, 1942). With the exception of the Tichenor limestone member and the 

Wanakah shale member as used by Buehler and Tesmer, in press of the Ludlowville shale, the stratigraphic units used in the present paper are as defined 

in a definitive paper on the detailed stratigraphy of 

the Hamilton group by G. A. Cooper (1930).

Trepostomatous Bryozoa occur most commonly in 

the Hamilton outcrops between Lake Erie on the 

west and Cayuga Lake in central New York State 

(figs. 1, 6). The outcrop area of the Hamilton between these lakes is a 10-mile belt extending eastward 

from Lake Erie. The rocks are nearly flat lying; the 

prevailing dip is to the southeast about 34 feet per 

mile (Cooper, 1930, p. 119). The main stratigraphic 

problems are concerned with facies changes and rather 

obscure lithologic differences at the boundaries between some members. Fortunately, thin distinctive 

faunal zones appear to be continuous over large areas 

and afford a measure of stratigraphic control.

The Hamilton group is primarily a clastic sequence 

consisting of calcareous mudstone, shale, and siltstone. 

A few thin, persistent limestone units, such as the 

Centerfield and Tichenor limestone members, are interbedded with the shales. The group shows a general 

increase in thickness eastward, and is 285 feet thick 

at Lake Erie and 680 feet thick at Cayuga Lake 

(Cooper, 1930, p. 121). As the clastic beds thicken 

eastward, the shale and mudstone that predominate in 

the Lake Erie region gradually change to siltstone in 

the Finger Lakes region. East of Cayuga Lake sandy 

beds are predominant.

MARCELLUS AND SKANEATELES FORMATIONS

No trepostomatous Bryozoa were found in the two 

lower formations of the Hamilton in the area studied. 

The Marcellus shale is generally a dark gray to black, 

bituminous, fissile shale that contains a sparse fauna.

The Skaneateles shale has the thin Stafford limestone member at the base. The Stafford is 15 feet 

thick at Lake Erie (Cooper, 1930, p. 216) and thins 

eastward, finally losing its identity east of Seneca 

Lake, where its position in the section is occupied by 

the Mottville member of Smith, 1916. At Lancaster, 

the Stafford contains small brachiopods, gastropods, 

trilobites, and fistuliporoid and fenestellid bryozoans. 

The superjacent Levanna shale of Cooper (1930) is 

a fissile to platy dark shale containing a sparse fauna

very similar to that of the Marcellus shale (Cooper, 

1930, p. 217).

LUDLOWVILLE SHALE

Trepostomatous Bryozoa first appear in the Centerfield limestone member at the base of the Ludlowville 

shale (fig. 2). They are very rare in the overlying 

Ledyard member of Cooper (1930) and become common to abundant in the poorly bedded, light-gray, 

calcareous shale and mudstone members in the upper 

part of the formation.

Centerfield limestone member. The Centerfield 

limestone member is predominantly limestone and 

occurs at the base of the Ludlowville shale. The member contains the lowest occurrence of trepostomatous 

Bryozoa known in the Hamilton group. The type 

locality is on Schaffer Creek, 1 mile north of Centerfield in the Canandaigua quadrangle. Here the Centerfield member is about 20 feet thick and is comprised 

of alternate thin limestones and shales. Both the 

limestones and shales are abundantly fossiliferous, 

typically containing large colonial and solitary corals 

and massive and encrusting fistuliporoid Bryozoa. 

Surrounding the larger more massive fossils is a 

matrix of comminuted fossil debris. Westward the 

member thins and is less shaly. At Blossom in the 

Depew quadrangle the Centerfield is only 4V£ feet 

thick; and west of this locality, typical Centerfield 

lithology is not known.

The Centerfield thickens east of the type section, 

and shale and mudstone become predominant. At 

Seneca Lake the lower 12 to 15 feet of the Centerfield 

is homogeneous mudstone containing a few thin, shaly 

limestone layers. The mudstone is sparsely fossiliferous; the limestones contain the typical coral assemblage. The matrix of the limestone between larger 

corals is a fine calcareous mud, not the broken fossil 

debris that is common farther west. The upper 15 

feet of the Centerfield at Seneca Lake is a soft, 

medium- or poorly bedded shale; 1- to 2-inch layers 

of more resistant fossil debris are common in this 

interval, and large nodules of limestone are scattered 

throughout. The fauna consists largely of brachiopods, trepostomatous bryozoans and a few small specimens of Pleurodictyum. The typical Centerfield coral 

fauna is not developed in this upper zone.

At Moonshine Falls on Cayuga Lake, the upper 3 

to 4 feet of the Centerfield is well exposed. This 

uppermost rock is composed of shaly limestone and 

limy shale. Large colonies of tabulate corals occur 

sparsely, and brachiopods, trepostomatous and fistuliporoid bryozoans, horn corals, and trilobites are 

common.
TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

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Windom member

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Wanakah shale

Kashong member of Cooper (1930)

~~~~~- ~___^ Portland Point member 

Menteth limestone member - ____^ of Cooper (1930)

 _

\y >

-- C^ Deep Run member of Cooper (1930) ~^ 

\ PV^ J^=> ir;« r<« ,.

Tichenor limestone member ./shale member

 ^^

 -> of Cooper (1930)

member as used by Buehler and Tesmer (in press) ^~^>

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Ledjfard member of Cooper (1930)

Pteropod bed </ Centerfield limestone member

FIGURE 2. The members of the Ludlowville and Moscow formations are arranged relative to their inferred time and geographic position (modified from Cooper and others, 1942) ; time lines are horizontal, geographic position from west to east along the outcrop belt of the .Hamilton group is indicated by the place names at top of diagram).

The Centerfield limestone member has a distinctive 

trepostome fauna. In general, zoaria of the Centerfield species occur in the interbedded shales and become more abundant eastward as the member becomes 

more shaly. Thus, the trepostomatous bryozoan element in the Centerfield faunule is most useful stratigraphically in the Finger Lakes region. Four species 

(fig. 3) are presently known only from the Centerfield 

member. Three of these, Trachytoechus variacellus, 

Leptotrypella mesostena mesostena, and Loxophragma 

leptum are fairly widespread geographically. Stereotoechus cf. S. typicus is known from one specimen 

in the Centerfield member in the Batavia quadrangle 

and is not important stratigraphically. T. variacellus 

is common in the upper few feet of the Centerfield 

member in the Finger Lakes region. In addition, 

Polycylindricus clausus is widespread geographically 

in the Centerfield member and occurs with T. variacellus in large numbers in the upper few feet of the 

Centerfield at Cayuga Lake; P. clausus also is very 

rare at a single Ledyard locality and there are a few 

specimens in the Windom member at the top of the 

Hamilton. Both T. variacellus (see p. 49) and the 

genus Polycylindricus (p. 67) have distinctive external appearances, and if found together in abundance 

are indicative of the Centerfield limestone member in 

New York.

Ledyard member of Cooper (1930). The Ledyard 

member is a shale that overlies the Centerfield limestone member. The type section is on Paines Creek, 

Ledyard township, Cayuga Lake. The Ledyard is 

continuous from its type locality to Lake Erie, and, 

except for local lenticular thickening, thins westward 

(see Sutton, 1951, p. 366). At Cayuga Lake the thickness ranges from 60 to 100 feet (Cooper, 1930, p. 224) 

and at Lake Erie the member is 30 feet thick. At the 

type section the Ledyard is a dark fissile shale with a 

few thin beds of medium to light gray, poorly bedded 

shale at irregular intervals. The fauna is sparse and 

generally similar to that of the Marcellus shale 

(Cooper, 1930, p. 224). In the White Creek area of the 

Batavia quadrangle the lower 15 feet of the Ledyard 

member is a light gray, poorly bedded shale that 

contains an abundance of chonetid brachiopods and 

the only specimens of Trepostomata found in the 

member. Above the 15 foot basal unit, the Ledyard 

is thin-bedded to fissile and fossils are rare. Because
STRATIGRAPHY

FORMATION Moscow shale Ludlowville shale

MEMBER

SPECIES

fc 

be

2.

o

3

Stereotoechus cf. S. typicus Duncan

Trachytoechus variacell.us (Hall)

Leptotrypella mesostena mesostena Boardman, n. subsp.

Loxophragma leptum Boardman, n. sp.

Leioclema confertiporum (Hall)

Polycylindricus clausus Boardman, n. sp.

Atactotoechus acritus Boardman, n. sp.

Dyoidophragma polymorphum Boardman, n. sp.

Leptotrypella 'mesostena provecta Boardman, n. subsp.

Loxophragma lechrium Boardman, n. sp.

Calacanthopora 1 senticosa Boardman, n. sp.

Leptotrypella amplectens (Grabau)

Polycylindricus asphinctus Boardman, n. sp.

Leptotrypella pachyphragma Boardman, n. sp.

multitecta Boardman, n. sp.

Atactotoechus cartus cartus Boardman, n. subsp.

Leioclema decipiens (Hall)

Leptotrypella asterica Boardman, n. sp.

amphelicta Boardman, n. sp.

magniporta Boardman, n. sp.

tuberata Boardman, n. sp.

Atactotoechus parallelus Boardman, n. sp.

Leptotrypella polita Boardman, n. sp.

Atactotoechus cartus pilatus Boardman, n. subsp.

Leioclema elasmaticum Boardman, n. sp.

Leptotrypella furcata (Hall)

Atactotoechus hystricosus Boardman, n. sp.

fruticosus (Hall)

FIOUUB 3. Stratigraphic distribution of the trepostomatous Bryozoa of the Hamilton group of New York. Numbers from 1 to 4 Indicate Increasing relative abundance of zoarla of a species In localities where that species occurs. The King Ferry shale member of Cooper (1930) is an 

eastern silty fades considered to be laterally equivalent to the Wanakah shale member as used by Buehler and Tesmer (In press), Tichenor 

limestone member and Deep Run members of Cooper (1930).

of their scarcity, trepostomatous Bryozoa have little 

stratigraphic value in the Ledyard member. However, 

the few specimens from the White Creek locality are 

important in tracing the phylogenies of several genera 

(p. 14).

Wanakah shale meniber as used by Buehler and Tesmer (in press). The Wanakah shale member overlies 

the Ledyard member of Cooper (1930) and is generally a fossiliferous shale and mudstone. The type 

locality of the Wanakah shale member is in the Wanakah and Lakewood Beach cliffs, along Lake Erie. As 

used here and by Buehler and Tesmer (in press), the 

Wanakah shale member includes the shale and mudstone sequence beginning with the Strophalosia and 

Pleurodictyum beds and terminating at the lowest 

limestone layer of the overlying Tichenor limestone 

member.

The Wanakah shows little regional change in thickness (see Sutton, 1951, p. 367) and can be traced as 

far east as Seneca Lake. East of Seneca Lake the 

member becomes more silty and sandy and loses its 

identity, becoming part of the King Ferry shale member of Cooper (1930). Trepostomatous Bryozoa are 

generally abundant in the Wanakah and are concentrated in two zones: the Pleurodictyum zone at or near 

the base of the member, and the Stropheodonta de-
6 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

missa zone in the upper few feet of the Wanakah 

shale member.

The Pleurodictyum zone is well exposed in the bed 

of Cazenovia Creek (locality 9, Depew quadrangle) 

where the zone is essentially a series of lenses of highly 

calcareous fossil material. The lenses are generally 

less than 1 foot thick and are separated by 3 to 4 

inches of less fossiliferous shale and mudstone. A few 

ramose zoaria were found with intact branches extending from the lenses into the surrounding shale. The 

fauna is characterized by the small tabulate coral 

Pleurodictyum, abundant small horn corals, brachiopods, and branching trepostomes, all well preserved. 

These relatively large fossils are embedded in a matrix 

of mudstone and comminuted fossils consisting mainly 

of broken crinoid columnals. In the Genesee Valley 

to the east, the Pleurodictyum zone is largely shale 

and mudstone with only a few thin lenses of fossiliferous material. Still further east of the Pleurodictyum 

zone is less conspicuous though it can be found in the 

King Ferry shale member in the Cayuga Lake area.

The strata of the Wanakah member between the 

Pleurodictyum zone and the Stropheodonta demissa 

zone are generally homogeneous poorly bedded shale 

and mudstone. These beds are poorly to moderately 

f ossilif erous; a few half-inch layers of broken fossil 

material occur at random.

The Stropheodonta demissa zone, which lies near 

the top of the Wanakah shale member west of the 

Finger Lakes area, contains most of the ramose trepostomes that are common in the Pleurodictyum zone. 

The lithology is generally similar to that of the 

Pleurodictyum zone. In the Canandaigua quadrangle, 

the upper 15 feet of the Wanakah has thin, limy fossiliferous beds and lenses that average 1 to 2 inches in 

thickness. These limy beds are separated by unfossiliferous shale and mudstone beds 3 inches to 2 feet thick. 

In the Seneca Lake region farther east, the thin fossiliferous zones containing trepostomatous Bryozoa occur 

throughout the Wanakah member.

Three species are restricted to the Wanakah shale 

member. Of these, Leptotrypella amplectens (Grabau) is easily recognized in the field by its constant 

association with the brachiopod Spinocyrtia granulosa 

(Conrad) and Aulocystis tubaeformis (Goldfuss) an 

auloporoid coral (p. 60). The species is fairly common where found, but appears restricted geographically in New York to the Buffalo and Depew quadrangles, the two extreme western quadrangles of the outcropping rocks of the Hamilton group. Polycylindricus asphinctus is less common but is found from Lake 

Erie to the Genesee Valley area. C alacanthopora?

senticosa is rare and occurs at only one locality, in the 

Buffalo quadrangle.

Leptotrypella multitecta (p. 57) is the most characteristic bryozoan species of the Wanakah shale member, occurring abundantly in both the Pleurodictyum 

and Stropheodonta demissa zones from Lake Erie as 

far east as the Batavia quadrangle and appearing 

again in the Cayuga Lake region in the King Ferry 

shale member, which is partly equivalent to the Wanakah member. Loxophragma lechrium is abundant in 

the Wanakah and King Ferry members from Lake 

Erie to the Cayuga Lake region. However, the species 

also occurs in the Kashong member (of Cooper, 1930) 

of the Moscow shale in the Genesee Valley and at 

Seneca Lake.

Tichenor limestone member. The Tichenor limestone member as used in this paper is bioclastic limestone interbedded with minor amounts of shale. The 

fauna of the limestones is characterized by massive 

colonial corals, encrusting fistuliporoid bryozoans, extremely large crinoid columnals, and many brachiopods. The fauna of massive colonies and bioclastic 

matrix probably indicates an ecological similarity with 

the Centerfield limestone member. The few trepostomes found in the Tichenor member occurred in the 

thin shale beds.

Cooper (1930, p. 226) drew the Wanakah-Tichenor 

boundary at the first appearance of the typical Tichenor fauna in the shale underlying the limestone of the 

Tichenor. The fauna in the shale beds underlying 

the limestones appears to change progressively upward from a calcareous mudstone fauna (see p. 10) 

rich in branching trepostomes to the coralline fauna 

that excludes the trepostomes. The species of trepostomes that occur in the transitional shale, which is 

here included in the Wanakah shale member as used 

by Buehler and Tesmer (in press), also occur in the 

Pleurodictyum zone near the base of the Wanakah.

Deep Run member of Cooper (1930}. This member 

overlies the Tichenor limestone member between the 

Genesee Valley area and Seneca Lake, where it is the 

highest member in the Ludlowville shale. Generally 

it is a hard brittle calcareous medium- to poorly 

bedded shale. A single zoarium of Leptotrypella 

tuberata was found in the Deep Run member at Canandaigua Lake.

King Ferry shale member of Cooper (1930}. The 

King Ferry shale member is generally a siltstone and 

is considered the lateral equivalent of the Wanakah 

shale, Tichenor limestone, and Deep Run members 

(Cooper, 1930, p. 228), which are distinguished west 

of the Cayuga Lake region (fig. 2). The type locality 

is at Clearview, King Ferry, Cayuga Lake. There the
STRATIGRAPHY

member is a homogeneous poorly bedded siltstone or 

silty mudstone with a sparse fauna distributed fairly 

evenly throughout the member. A Portland Point on 

Cayuga Lake, however, the member contains abundantly fossiliferous beds averaging about 1 inch in 

thickness and separated by 2 to 4 inches of nearly 

barren shale. Partly complete branching trepostome 

zoaria were found lying horizontally within the fossiliferous layers and 1 zoarium was standing vertically 

between 2 fossiliferous layers. However, most of the 

fossiles in the thin zones are fragmental.

Leptotrypella multitecta is fairly common 30 or 40 

feet from the top of the King Ferry shale member 

that measures just over 130 feet in total thickness in 

the Cayuga Lake region. If it could be assumed that 

L. multitecta was restricted to the Wanakah shale 

member or time-rock equivalents of that member, the 

lower three-fourths of the King Ferry member could 

be correlated with the Wanakah. Unfortunately, other 

species of Trepostomata occurring in the 2 collections 

are of little stratigraphic value in the King Ferry or 

Wanakah members and there is no evidence that L. 

multitecta could not have continued in post-Wanakah 

sediments in the Cayuga Lake region. Atactotoechus 

parallelus is known from just 1 zoarium found in the 

King Ferry member so the species is too rare to have 

stratigraphic significance. Leptotrypella tuberata is 

known from a zoarium in the Deep Run member and 

another in the King Ferry member, so that species 

also has little stratigraphic value. Besides these 2 

rare species, the remaining 5 species found in the 

King Ferry member also occur in the Wanakah member and 3 of them are found in the Moscow shale 

above.

MOSCOW SHALE

The Moscow shale is characterized by calcareous 

shales and mudstones containing abundant and well 

preserved fossils. The dominant Trepostomata are 

large ramose species that were apparently short lived 

and have considerable stratigraphic and time significance.

Portland Point member of Cooper (1930}. The 

Portland Point member is essentially an impure limestone interbedded with varying amounts of mudstone 

and shale. The type section of the member is in the 

creek at Portland Point on Cayuga Lake. The member here is 8l/2 feet thick (Cooper, 1930, p. 229) and 

has a basal 1 foot crinoidal limestone followed by 

alternations of fossiliferous shale and impure limestone 

in discontinuous beds and lenses.

The basal limestone of the Portland Point member 

extends westward and is considered to be equivalent 

to the Menteth limestone member (Cooper, 1930, p.

230). The Menteth limestone member can be traced 

westward beyond the Genesee Valley and no trepostomes were found in it.

The Portland Point member continues Avestward to 

the Canandaigua Lake region where the interval above 

the basal limestone is a homogeneous mudstone 15 feet 

thick followed by a 3-foot bed of 1- to 3-inch clastic 

limestone layers interbedded with thin shale partings.

Only three species were collected from the Portland 

Point member. Atactotoechus cartus cartus occurs 

abundantly, but only at one locality on Canadaigua 

Lake. Dyoidophragma polymorphum and Leptotrypella asterica are very rare in the Portland Point and 

are not important stratigraphically in that member.

Kashong member of Cooper (1930). The Kashong 

member is composed of shale, mudstone, and limestone 

and extends from the Cayuga Lake region westward 

into the Depew quadrangle. The type locality is on 

Kashong Creek where the unit is 24 feet thick (Cooper, 

1930, p. 231). The lower 15 feet of the Kashong here 

consists of hard, limy fossiliferous layers averaging

1 inch in thickness alternating with relatively unfossiliferous mudstone and shale beds ranging from 3 

inches to more than 1 foot in thickness. Overlying 

the 15-foot basal zone is a zone of large calcareous 

pyrite-bearing concretions in a shale matrix. Fossils are rare in this zone. The concretion zone is 

overlain by resistant hard homogeneous, impure limestone beds containing few fossils, interbedded with 

fossiliferous shale and mudstone averaging 1 foot in 

thickness. The limestone beds range in thickness from

2 inches to more than 1 foot. The fossils in the shale 

and mudstone beds are concentrated in thin layers. 

West of the Genesee Valley the Kashong loses most 

of the thin fossiliferous layers and consists of homogeneous mudstone yielding few fossils.

Leptotrypella asterica is the most abundant and 

characteristic species in the Kashong member. The 

species is very rare below this member although its 

range extends down to the Wanakah shale member. 

The other stratigraphically important species is Atactotoechus cartus pilatus that is known only from the 

Kashong and is common and geographically widespread. Leptotrypella polita is known from a single 

zoarium at the type locality of the member. Two 

other species that are abundant in the Kashong, 

Dyoidophragma polymorphum and Loxophragma 

lechrium, are long ranging and common in members 

below the Kashong member.

Windom member. The Windom is the shale at the 

top of the Hamilton group and its type section is on 

Smokes Creek at Windom, in the Buffalo quadrangle. 

The member increases in thickness eastward from 50
8 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

feet at the type locality to 120 feet at Cayuga Lake 

(Cooper, 1930, p. 232). In the Depew quadrangle the 

Windom is a light-gray mudstone or shale containing 

few fossils and few thin limy zones. In the Genesee 

Valley the Windom is abundantly fossiliferous; the 

fossils are concentrated in 1- to 3-inch layers that are 

interbedded with relatively unfossiliferous mudstones 

averaging 1 foot in thickness. Some thin layers contain comminuted fossil debris, others contain forms 

showing little disturbance or mechanical breaking. 

This same general lithology persists eastward to Cayuga Lake as the member thickens. Large branching 

trepostomes, fistuliporoids, and favositid corals are 

abundant at various levels in the upper half of the 

Windom in the Cayuga Lake region.

The Windom has a distinctive trepostome fauna 

with four species (fig. 3) restricted to the member. 

Of these, Leptotrypella furcata and Atactotoechus 

fruticosus occur abundantly between the Genesee Valley and Cayuga Lake. Leioclema elasmaticum is 

fairly common from the Genesee Valley to Seneca 

Lake and Atactotoechus hystricosus is known only 

from the Windom member at Owasco Lake. The 

remaining species known in the Windom are not 

common in the member and are also found in other 

members in the Hamilton group.

PALEOECOLOGY

BRYOZOA AND ENVIRONMENTS

Bryozoa are considered to be potentially useful indicators of physical environment owing to the varied 

growth habits of the colonies and the observed environmental significance of comparable growth habits 

in living spe'cies. L. W> Stach (1935, 1937) studied 

zoarial forms of living Bryozoa with reference to different environments and separated them into "(a) 

stable forms and (b) unstable forms" (Stach, 1937, 

p. 80). Zoaria in the first group are incapable of 

modifying their growth form, regardless of environment or changes in environment. "The stable zoarium 

therefore cannot adjust itself to or survive adverse 

environmental conditions, and is consequently restricted to definite habitats." The unstable types are 

capable of modifying their zoarial growth habit in 

response to the environment. For example, a species 

that is normally ramose ("vinculariform") and vertically elongated in quiet waters becomes incrusting 

("membraniporiform") in strongly agitated waters 

(Stach, 1937, p. 82).

The developing zoarium of a species with an unstable zoarial 

form apparently has a tendency to assume an erect slender 

form which, in quiet water, will enable it to extend through 

a greater volume of water from which to obtain food. When

the larva of such a form is carried into a zone where the 

motion of the water is strong, the uncalcified growing points 

are unable to assume an erect position and are kept flattened 

to the substratum, and are thus forced to assume a _membraniporiform habit, the continual movement of the water 

ensuring adequate food supply and aeration.

The principle of stable and unstable growth forms 

for bryozoan species appears to be valid in the Hamilton trepostomes, since some species show two growth 

habits in the same zoarium and in different zoaria and 

other species display constant growth forms. Species 

with unstable growth habits include: Leioclema confertiporum (pi. 3) with incrusting and subramose 

habits in separate zoaria; Leptotrypella multitecta 

(pis. 7, 8), L. furcata (pi. 11), L. amplectens (pi. 12, 

figs. 1-5), Atactotoechus acritus (pi. 17, figs. 1-5), and 

Loxophragma lechrium (pi! 22) all exhibiting incrusting and ramose growth habits in the same and separate 

zoaria. Until proved otherwise, however, most of the 

Hamilton species must be considered as stable species 

existing in a constant growth habit.

The possible application of the stable and unstable 

concept of colonial growth habit of bryozoans to paleoecology requires considerably more data than are now 

available. The incrusting mode of growth in itself 

has little significance, for incrusting species belonging 

to stable groups can occur in both quiet and rough 

water. But the absence of vertically extended branching zoaria in addition to the dominance of incrusting 

forms would be suggestive of a rough-water environment. The coral-bearing limestone f acies of the Hamilton group (p. 9) is an example. If the incrusting 

forms belonged to unstable species that were also 

known to be branching, their occurrence in the absence 

of ramose forms Avould suggest rough \vater more 

strongly. The occurrence of branching forms, especially branching forms of species known to be of the 

unstable group, would suggest a relatively quiet water 

environment. The more robust branching colonies 

would have greater physical strength to resist rough 

water and would be a weaker argument for absolutely 

quiet water. If both ramose and incrusting growth 

habits of unstable species occur together, it could mean 

that the environment alternated between water quiet 

enough for branching growth and rough enough to 

require incrusting growth. The calcareous mudstone 

facies of the Hamilton group (p. 10) contains ramose 

forms of species that are found in minor numbers in 

incrusting growth habits. Such occurrences, with 

other types of evidence such as the general lack of 

transportation of fragments of the colonies after death, 

suggest a generally quiet water environment with 

minor areas or times of rougher water.
PALEOECOLOGY

LITHQFACIES AND BRYOZOAN FAUNAS OF THE 

HAMILTON GROUP

The general distribution of bryozoan faunas of the 

Hamilton group is closely correlated with lithofacies 

(rock types). Stratigraphic application of these 

faunas requires recognition of at least the major environments and their geographic and inferred time 

relationships.

In the outcrop area of the Hamilton group between 

Lake Erie and Cayuga Lake are five major lithofacies, 

each with a characteristic fauna. Both vertical and 

horizontal transitions between lithofacies and their 

associated faunas are common within the members of 

the formations in the Hamilton group. Trepostomatous bryozoans have not been found in two of the lithofacies, occur in small numbers in two others, and are 

abundant in the fifth.

Dark shale fades. This facies is characterized by 

black to medium-gray well-bedded shale. No trepostomes have been found. The dark shale fauna is 

meager, and the number of species is restricted. It 

has been called the "Marcellus" or "Leiorhynchus" 

fauna by Cleland (1903) and Cooper (1930). The 

typical "Leiorhynclius" fauna listed by Cleland (1903, 

p. 23) includes Leiorliynclius, Clionetes, Orbiculoidea, Strophalosia, Lunulicardiwn, Nuculites, Nucula, Styliolina, Tentaculites, and Phacops.

The dark shale facies is best developed in the Marcellus shale, the Levanna shale (of Cooper, 1930) of 

the Skaneateles shale, and the Ledyard member (of 

Cooper, 1930) of the Ludlowville shale. The most 

extreme development of the dark shale facies is found 

in the Marcellus. This formation normally is a darkgray to black shale that is fissile and commonly develops platy bedding cleavage. The Ledyard member of 

the Ludlowville is black and fissile in the Cayuga Lake 

region and gradually becomes lighter in color and less 

well bedded to the west.

The black shale facies with its restricted fauna is 

ordinarily interpreted to indicate unfavorable environmental conditions for normal marine assemblages. 

The general makeup of the fauna suggests a poorly 

aerated, possibly brackish water environment. Styliolina and Tentaculites (Wells, 1947, p. 123, 124) might 

be considered planktonic forms living in the surface 

waters. The remainder of the fauna was benthonic, 

living on and in black, organic, oxygen poor muds.

Sandstone facies. Sandstones are rare in the Hamilton group between Lake Erie and Cayuga Lake, but 

more common eastward. The trepostomatus Bryozoa 

do not occur in the sandy beds and thus are generally 

rare east of Cayuga Lake. The fauna of the sandstones is characterized by an increase in the number of

pelecypods and a relative decrease in the number of 

brachiopods as compared with the siltstone and calcareous mudstone facies to the west.

Siltstone fades. The siltstone facies might be considered to represent a transitional environment between the optimum environment of the calcareous 

shale and apparently inhospitable environment of the 

sandstone. Cooper's King Ferry shale member of the 

Ludlowville is a typical representative of this lithofacies in the Cayuga Lake region. The trepostomes of 

the siltstone facies are few. Of the 15 species occurring in the Wanakah shale member as used by Buehler 

and Tesmer, Tichenor limestone member, and Deep 

Run member of Cooper, the westward equivalents of 

the King Ferry, only 6 occur in the siltstones of the 

King Ferry. One species, Atactotoechus parallelus is 

known only from the King Ferry member but is very 

rare.

The lack of trepostomes in the sandstone facies and 

their restricted occurrence in the siltstone facies is at 

least in part due to lack of adequate substrate for 

attachment of the zoaria. Duncan (1957, p. 784) 

states that 

shifting sands and muddy bottoms without admixture of 

larger debris are not suitable for fixation of most larvae 

* * * The general absence of bryozoans in most marine sandstone and some shale is attributable in large part to lack of 

objects for attachment.

Coral-1)earing limestone fades. The limestone facies 

is typically developed in the Centerfield limestone and 

Tichenor limestone members of the Ludlowville shale. 

The limestones are largely of organic origin, displaying large colonies of' Favosites, large solitary corals 

such as Heliopliyllum and Cystipliyllwn, incrusting 

fistuliporoid Bryozoa, and many species of well-preserved brachiopods. This fauna of relatively large, 

massive specimens is surrounded by a clastic limestone 

matrix consisting of crinoid columnals and the broken 

debris of fenestellid bryozoans and other fragile fossils.

Trepostomatous Bryozoa are very rare in the limestone beds and gradually increase in numbers as the 

limestone becomes more shaley and approaches the 

composition of a calcareous shale or mudstone. Trepostomes occur in the shale partings in the limestone 

members. Examples of transitions to normal calcareous shales are common both vertically and horizontally. As the Centerfield becomes more impure and 

muddy eastward in the Finger Lakes region (p. 3), 

the trepostomes increase in number. Trachytoeclius 

variacellus and Polycylindricus ' clausus are few in 

number west of the Finger Lakes region but occur 

abundantly at Cayuga Lake. The fauna of the basal 

mudstone and shale in the Tichenor shows a gradual
10 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

vertical change from the fauna of brachiopods and 

ramose trepostomes of the underlying Wanakah to the 

fauna of corals and incrusting fistuliporoid bryozoans 

of the Tichenor.

The coral-bearing limestone facies seems to represent 

a shallow, rough-water environment. The comminuted 

debris of the more fragile elements of the fauna, the 

massiveness and apparent physical strength of the well 

preserved forms, and the predominance of low, incrusting fistuliporoid Bryozoa over ramose trepostomes 

all support this interpretation.

Calcareous mudstone facies. Optimum environmental conditions for trepostome development were afforded by the light-gray calcareous mudstones and 

shales of the Hamilton group. Sediments of the mudstone facies that contain abundant macrofossils are 

characteristically an alternation of 1- to 3-inch beds of 

concentrated fossil material and 1 foot beds of unfossiliferous shale or mudstone. Individual unfossiliferous zones have a considerable range in thickness and a 

feAv fossiliferous concentrations develop 1-foot thicknesses in discontinuous lenses. Some of the thin fossiliferous beds consist of comminuted fossil debris, 

others contain whole specimens showing little sign of 

wear or transportation. Also within the calcareous 

mudstone facies are relatively large thicknesses of 

homogeneous mudstone and shale that contain few 

macrofossils.

The Wanakah shale member consists of calcareous 

shale and mudstone throughout. The important f aunal 

zones in the Wanakah such as the Strophalosia zone, 

the Pleurodictyum zone, the trilobite zones, and the 

Stropheodonta demissa zone are all examples of the 

thin beds of concentrated fossil material. The intervening thicknesses of the Wanakah member generally 

consist of the homogeneous shales and mudstones 

showing few fossils. From the Genesee Valley region 

to Seneca Lake, Cooper's Kashong member and the 

Windom member of the Moscow shale are characterized throughout their thicknesses by the alternating 

thin fossil beds and unfossiliferous shales. The Windom member extends eastward to Cayuga Lake displaying similar alternations and abundant macrofaunas.

In all occurrences of ramose trepostomes found in 

place in the sediments of the mudstone facies the 

broken pieces of the branches are in zoarial groupings. 

Most commonly the fragments occur in lense-shaped 

or irregular masses as if the zoaria were compressed 

by the weight and compaction of the sediments without otherwise being moved from their living position. 

A few zoaria are oriented either perpendicularly or 

parallel to the bedding without any differential movement of the constituent fragments. Most zoaria seem 

to have originated in the thin fossiliferous beds. Very 

rarely a zoarium can be followed vertically from one 

thin fossiliferous bed, through an unfossiliferous mudstone, and into the superjacent fossil concentration.

The fauna that is characteristically associated with 

the trepostomes in the calcareous mudstone facies includes a number of brachiopods. Especially common 

are spirifers, Athyris spiriferoides (Eaton) and species 

of Stropheodonta. Small horn corals, species of the 

small colonial coral Pleurodictyum^ the ramose favositid genus Trachypora, and a few auloporoid corals 

are commonly associated with the trepostomes.

John L. Rich (1951) suggested two slightly different hypotheses for the origin of the thin limy 

fossiliferous beds and the interbedded unfossiliferous 

mudstones. If a slight difference in depth is assumed between the depositional surface and wave base 

the deposits could have been affected by wave action 

during storms. The temporary lowering of wave base 

would have winnowed the mixture of mud and bottom 

life placing at least the finer muds into suspension. 

As a result a concentrate of benthonic life would be 

left on the bottom. After storms the fine muds settled 

again forming a relatively unfossiliferous layer resting on the thin fossiliferous zone (Rich, 1951, p. 5).

The alternative origin (Rich, 1951, p. 18) seems 

more plausible when applied to the thin zones that 

contain relatively unbroken fossils and ramose colonies 

in growing position. Lag concentrates might have 

formed (Rich, 1951, p. 13) consisting of "* * * fossil 

shells * * * concentrated locally as a result of contemporaneous nondeposition of the finer sediments in 

which they would normally have been bedded." Thus, 

abundant benthonic communities would be formed 

during periods of bypassing of terrigenous muds 

under normal but variable current or wave action.

Whatever the mode of origin, physical conditions 

were repeated many times during deposition of the 

shales of the Ludlowville and Moscow formations. 

Wave or current action was not generally strong 

enough to prevent growth of branching colonies or to 

transport the colonies after their death. The colonies 

were robust enough, however, and possessed of enough 

strength so that some current or wave action cannot 

be completely ruled out. It is not uncommon to see 

more fragile shells badly broken in the matrix surrounding a nearly complete branching zoarium.

In thicker beds of shale and mudstone that do not 

contain the thin limy zones, the fauna appears to be 

scarce. The scarcity of fossils in the homogenous 

shales may be real or merely reflect the difficulty of 

finding the specimens that could be scattered evenly
PALEOECOLOGY 11

through the rock. In either case, deposition of muds 

seems to have been too rapid and continuous to allow 

benthonic faunas to form coquinoid concentrations.

TIME AND STRATIGRAPHIC RELATIONS

Several of the lithologic and faunal features of the 

rocks of the Hamilton group suggest a means of relating the rocks within the group to their relative 

time of deposition. If correctly interpreted, such 

time relationships are extremely useful in the taxonomic evaluation of morphologic characteristics that 

would otherwise be difficult to understand.

The Hamilton group contains several extremely 

thin beds, measured in inches, characterized by coquinoid concentrations of one to several species that can 

be traced for ma.ny miles along the outcrop (p. 10). 

Examples include the Stroplialosia beds (Cooper, 

1930, p. 225) at the base of the Wanakah member that 

can be traced from Lake Erie to the Genesee Valley 

area, and the trilobite beds (Cooper, 1930, p. 225) that 

are traceable from Lake Erie to Canandaigua Lake.

Distinctive lithologic units are a second feature of 

the Hamilton group and are also widespread geographically. Examples are the Centerfield limestone 

member of the Ludlowville that extends from the 

Depew quadrangle to Canandaigua Lake with little 

lithologic change. The Tichenor limestone member of 

the Ludlowville and the Menteth limestone member of 

the Moscow shale have essentially the same lithology 

over comparable areas. The nodular zone near the 

top of Cooper's Kashong member of the Moscow in 

the Finger Lakes region is another widespread lithologic zone. These lithologic units are generally stratigraphically parallel to the thin coquinoid beds mentioned in the preceding paragraph.

Superimposed on the pattern of the widespread lithologic units of the Hamilton rocks are the zonules, 

locally recognizable biostratigraphic units, based upon 

morphologically distinct species of trepostomatous 

Bryozoa. These zonules are widespread geographically 

and are parallel to the thin lithologic units and the 

coquinoid beds of the preceding paragraphs. Further, 

these zonules are wholly contained within individual 

named members of formations of the Hamilton group. 

Examples of easily identifiable species on which zonules 

are based include: Tracliytoechus variacellus, found 

only in the Centerfield limestone member of the Ludlowville (the only species of Tracliytoechus in the 

Hamilton group) ; Polycylindricus aspliinctus, occurring in the Wanakah shale member as used by Buehler 

and Tesmer from Lake Erie to the Genesee Valley 

area and easily distinguished by the lack of an internal 

cylinder (p. 68) ; Leptotrypella asterica, the dominant

bryozoan species in the Kashong member of the Moscow shale that occurs very rarely in the Ludlowville 

shale below (three Ludlowville specimens identified) ; 

Leptotrypella furcata and Atactotoechus fruticosus, 

two species with easily recognized morphologic characteristics that are known only from the Windom 

member of the Moscow shale. L. furcata occurs 

throughout the thickness of the Windom and is found 

abundantly from the Attica quadrangle to Owasco 

Lake. A. fruticosus occurs between the Genesee Valley and Cayuga Lake.

In addition to the morphologically distinct group of 

species for which zonules are named, several genera 

show morphologic trends that are considered to be 

evolutionary in origin. The same stage of evolution, 

morphologically denned, in any one lineage, occurs at 

the same stratigraphic position, as defined by the 

marker beds and by the zonules of distinctive species.

As a result of the noted alinement, marker beds, 

zonules, and evolutionary stages are considered to be 

isochronous throughout the area studied. Therefore, 

the named stratigraphic members defined primarily on 

marker beds are considered to be parallel to time lines.

If it were possible to assume fairly constant rates of 

speciation for the bryozoan lineages discussed in this 

paper, a rough estimate could be made of the relative 

amounts of time represented by the members and the 

periods of nondeposition between the members. Such 

an estimate would indicate that considerably more time 

elapsed between the Kashong and Windom members 

with their distinct faunal differences than between the 

Centerfield and Ledyard members or between the 

Ledyard and Wanakah members, both showing only 

subspecific differences in two genera. Also, there is a 

strong indication that less time is represented by the 

preserved sediments than the intervals of nondeposition in the Hamilton group. Unfortunately, the 

assumption that time is uniformly proportional to 

morphologic change in phylogenetic lineages probably 

is not defendable when applied to a problem in such 

detail.

The paleogeographic setting for the Hamilton deposits would no doubt clarify and explain many factors in the time and stratigraphic relationships of the 

beds. Data on the location of the margin of the basin 

of deposition nearest the western and central New 

York area would be of considerable help. Unfortunately, the writer knows of no acceptable evidence 

establishing the position or positions of such a strandline. Grabau (1917, p. 950) inferred the Buffalo axis, 

running through the Lake Erie region in a generally 

northeast direction, to explain the westward thinning 

of the Hamilton group and superjacent Tully lime-
12 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

stone in New York. There is no evidence, however, 

that this axis was subaerial and formed a land barrier 

between the New York and Ontario basins.

The paleogeographic map of the Skaneateles, Ludlowville, and Moscow formations (Schuchert, 1955, 

map 36) shows the northern boundary of the Hamilton 

basin to be generally parallel to the present east-west 

outcrop of the Hamilton in western and central New 

York. Such a northern boundary was also suggested 

by G. A. Cooper (oral communication, 1954) to account at least partly for the nature of the Hamilton 

rocks and their inferred relations to time. Thus the 

thin coquinoid layers, the distinctive lithologic units, 

and the parallel zonules would have their east-west 

distribution controlled by elongated east-west belts of 

similar environment that were controlled in turn by 

distance from the hypothetical northern shoreline. If 

the belts of similar environment were wide enough in 

the north-south direction, embayments causing northsouth indentations of the standline and generally parallel shifting of benthonic environments would not be 

important enough to mask the general east-west continuity of the thin and distinctive sediments. The 

northern emergent area would be low lying, contributing small amounts of terrigenous material to the basin, 

in contrast to higher lands in the emergent area east 

of the present Hamilton outcrops that contributed 

more and coarser elastics, as reflected in the Hamilton 

rocks of eastern New York.

Another plausible hypothesis for the paleogeographic setting of the, Hamilton would place the western and central New York region in the center of the 

basin without shoreline control. The rocks now exposed in outcrops could have been part of the deposits 

of a large equidimensional area of generally equal 

benthonic environment during any one period of time. 

Subsurface investigation could yield information that 

would effectively test this hypothesis.

EVOLUTION

Species of the trepostomatous Bryozoa of the Hamilton group can be divided into two groups according 

to their morphologic distinctness and observable phylogenetic relationships. One group of species shows 

no taxonomically important morphologic change in 

time or space and is easily recognizable. A second 

group of species demonstrates transitional morphologic changes or trends in time and space that are 

considered to be of taxonomic value. This second 

group of species, plus a limited number of the morphologically distinct species that contain comparable 

morphologic features, have been arranged into inferred phylogenetic lineages (see Leptotrypella. p. 

52, 63, figs. 23-24; Atactotoechus, p. 70, figs. 25, 26;

and Loxophragma, p. 79, fig. 27; for more detailed 

discussions).

The morphologically distinct species are stratigraphically short or long ranging. The easily recognized species of restricted stratigraphic range are 

ideally suited for the establishment of zonules (see p. 

11). Species that are long ranging include Dyoidophragma polymorphism, occurring from the Centerfield limestone member of the Ludlowville to the Windom member of the Moscow; Leioclema decipiens, 

ranging from the Wanakah shale member of the Ludlowville to the Kashong member of the Moscow; and 

Leptotrypella magniporta, ranging from the Wanakah 

to the Windom member of the Moscow shale at the 

top of the Hamilton group.

Species of the group containing transitional forms 

are short or long ranging in time and develop recognizable morphologic changes considered to be of taxonomic value within the time of the Tioughnioga stage 

of Cooper. These gradual morphologic changes with 

time permit the recognition of phylogenetic lineages. 

Species and subspecies of a phylogenetic lineage generally are difficult to recognize because of a few transitional forms. In this paper the placing of morphologically transitional zoaria into taxons is based on 

the essentially isochronous nature of each member of 

the Hamilton group. A group of zoaria from a member that shows variation about a central tendency and 

morphologic characteristics that are transitional with 

taxons in adjacent members, is considered an interbreeding complex and a single taxon in a restricted 

interval of time. Therefore, a species or subspecies 

contains the zoaria of the plexus or phylogenetic lineage that are closely related in time as well as in morphology.

The grouping of the zoaria of a phylogenetic lineage into species and subspecies partly on the basis of 

occurrence in time and statigraphic units in the Hamilton group results in some morphologic overlap between taxons if evolution is slow relative to the vertical representation of the available fossil record.

The alternative solution to the treatment of morphologically transitional or overlapping forms from 

several superimposed zones would be the differentiating of species wholly on morphology, resulting necessarily in arbitrary morphologic boundaries for taxons 

without regard for time and stratigraphic relationships. It is believed that consideration of time and 

stratigraphic occurrences and the recogition of possible phylogenetic lineages as indicated by morphologic trends is the more natural and statigraphically 

useful basis for the solution of otherwise confusing 

taxonomic problems.
EVOLUTION 13

O

W

I

O

1;.;.;vv.'.'.-.'.'.'.'.yvyvv/.-.v.I.-/.-.^.>/.-.-.'.\i//.'.'.< .'r.-.I//.-/.> .T

Windom member

_____ Kashongjy f l^mfj ...««...».^««t« «»»«»«»»«» f^f »» ««.» 

------ - - - - - - - - - - - - - - - - - - - - - - - - - -'- - - - 

member of

ooper (1930) _ _____ 

g _.-._-- _.---_>_- -J-J-.-JY^ .......... J^^V.^^^^^^^sa±is^JIBI^TOi^TOI^^n^i^nC?^^. Portland Point

VIIf U^llXllrf lid I « Jiff llXJfcf IT* *x

Menteth limestone member nipiiMi-ii.itrir«»xi«i»ji«v - v ^ /,«,.«x l|in^n>lniKInnittfiWlHK''-v^;ooper (1930)

Deep Run member III 1111 llmjlKI8l8l8l81fil Jfc'-'l ''.''. ~<o 3

........................................... of c°°per (1930) 1111111111 Iflnl8l8l8lffl818:::::l 2

0>

Tichenor limestone member llllllllllllllllllinflJfilSiS*'''*! «*

 llllilllliillllllillllll!^SIff.''.'''l^~ ~ 43

Wanakah shale member as used lllllllllllHlllllllllllrHuU't'X'i ' ' ' c £ 

by Buehler and Tesmer (in press)

b

, ;:; Ledyard member of Cooper (1930)

, , , / Centerfield limestone 

Pteropod bed <

X. member

, EXPLANATION

L. furcata 

L. asterica 

L. tnultitecta 

L. mesostena provecta 

L. m.esostena m.esostena 

Subgenus Leptotrypella Subgenus Pycnobasis

FIGURE 4. Time-space ddagram of the occurrence of the genus Leptotrypella in the Hamilton group of New York. The members of the Ludlowvllle and Moscow formations are arranged relative to their inferred time and geographic position (modified, from Cooper and others, 1942) ; 

time lines are horizontal, geographic position along the east-west outcrop belt of the Hamilton group is indicated by the place names at top 

of diagram. The superimposed polygons are defined! by, and include, all known occurrences of the subgenus (Pycnobasis) and the species of 

( Leptotrypella) that are discussed phylogenetically in this paper.

D

O

03 

O

O

s

a

TIME AND SPACE RELATIONS OF LINEAGES

Figures 4 and 5 depict the inferred time and space 

relations of some of the species involved in phylogenetic lineages. A polygon is drawn about the outermost points of occurrence of collections that are located by plotting their inferred time, taken from 

stratigraphic data, against their known geographic 

position. The geographic positions can be fairly 

accurately .represented in the plane of the chart because of the fortuitously linear configuration of the 

outcropping area of the Hamilton rocks.

Two species showing overlapping areas on such a 

time-space chart, are potentially sympatric in occurrence during the time and in the region represented 

by the overlap. Unfortunately, an overlap obtained 

on such a basis does not definitely demonstrate a sympatric relationship. The large polygon representing 

A. acritus in fig. 5 no doubt has little reality in indicating the actual occurrence of the species in time and

space within the outcrop area. The collections themselves give a minimum representation of the occurrence of a species. Expansions and contractions of 

east-west geographic occurrence with time could very 

well have occurred, giving the eastern and western 

margins of the polygons many fluctuations. There 

could have been geographic areas of nonoccurrence in 

the outcrop belt during any time unit. In addition, 

migrations completely out of the outcrop area and 

back again were possible during the time unit represented by the surviving sediments. Sympatric e,xistence is indicated only when two species are commonly 

found in the same beds over a considerable area.

The range chart (p. 16) shows that Leioclema confertiporum and L. decipiens occur together in two 

geographically widely separated collections in the 

Wanakah shale member of the Ludlowville, indicating 

that the species were probably sympatric. Lack of 

morphologically transitional specimens precludes plac-
14 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

Portland Point 

member of Cooper 

(1930)

Tichenor limestone 

member

 y/'Wanakah shale member as used by Buehler

member of Cooper

' Centerfield limestone member .' '

EXPLANATION

A. cartus pilatus

A. cartus cartus

A. acritus

A. hystricosus 

A. fruticosus 

A. parallelus

FIGURE 5 Time-space diagram of the occurrence of the genus Atactotoechua in the Hamilton group of New York. The members of the Lutllowville and Moscow formations are arranged relative to their inferred time and geographic position (modified from Cooper and others, 1942) ; 

time lines are horizontal, geographic position along the east-west outcrop belt of the Hamilton group is indicated by the place names at top of 

diagram. The superimposed polygons are defined by, and include, all known occurrences of the species of the genus Atactotoechus.

ing these two species in a single species. Leptotrypella 

multitecta, L. amplectens, and L. magniporta occur 

together in 1 locality in the Wanakah member, and 

L. multitecta occurs in 2 other collections with L. 

magniporta and in 3 other collections with L. amplectens. There is no morphologic evidence of phylogenetic connections between the 3 species, and the 

environmental niche of L. amplectens was certainly 

highly specialized (p. 61) and different from the 

other 2 species. Leptotrypella asterica occurs in 2 

collections with L. multitecta, 1 collection from the 

Wanakah member of the Ludlowville, the other from 

the partly equivalent King Ferry member, so these 2 

species may well have been sympatric before L. asterica became prolific in the Kashong member of the 

Moscow. The few other instances of any 2 species of 

the same genus in the same collection are single occurrences and their possible sympatric relationships cannot therefore be demonstrated.

On the basis of known occurrence, the bryozoan 

fauna of the Ledyard member of the Ludlowville was 

geographically restricted within the Hamilton area to

the White Creek locality, represented in figure 4, by 

the pattern for L. mesostena provecta. Atactotoechus 

acritus also occurs in the Ledyard at that locality so 

the polygon for A. acritus in figure 5 might better be 

indented to that single locality at the level of the 

Ledyard member. The generally unfavorable environment of the Ledyard sediments (p. 9) and resulting 

geographic restriction is accompanied by recognizable 

morphologic changes in several lineages. Conceivably, 

the generally unfavorable environment could have 

started the evolutionary trends recorded in the single 

White Creek collection and continued in the subsequent Wanakah deposits. Besides the intermediate 

subspecies Leptotrypella mesostena-provecta (p. 56), 

the Atactotoechus cartus lineage probably started in 

the Ledyard (p. TO) and the Loxophragma leptum-L. 

lechrium lineage contains intermediate zoaria from the 

Ledyard member (p. 79).

The time-space diagram of Leptotrypella (fig. 4) 

and Atactotoechus (fig. 5) suggests a certain amount 

of geographic localization of speciation within the 

trepostomes (see also p. 81). All four of the species
EVOLUTION 15

of the subgenus L. (Pycnobasis) are limited geographically to the Finger Lakes region. L. (Leptotrypella) asterica .first appeared in the King Ferry 

member of the Ludlowville at Cayuga Lake and 

spread westward out of the Finger Lakes area during 

the deposition of the Kashong member of the Moscow, 

where it became abundant. Atactotoeclius parallelus 

and A. hystricosus are limited geographically to the 

Cayuga and Owasco Lake areas.

An explanation for the apparent geographic restrictions of these morphologically distinct forms is 

suggested by the proximity of the eastern limit of the 

occurrence of the trepostome fauna. The amount of 

silt and sand in the sediments increases very gradually 

in the Finger Lakes area and extends eastward, becoming the dominant lithology. No doubt the influx 

of silt and sand was effective in limiting the eastward 

occurrence of trepostomes and could have produced 

an eastward-changing environment within the Finger 

Lakes region that influenced speciation.

The changing environment of the Finger Lakes area 

was not unfavorable to several species of trepostomes 

that grew abundantly there in Tioughnioga time. 

Traclvytoechus variacellus and Polycylindricus clausus 

are abundant in the Centerfield limestone member at 

Cayuga Lake, Leptotrypella multitecta is fairly common in the siltstones of the King Ferry member at" 

Cayuga Lake, and Leptotrypella furcata and Atactotoechus fruticosus are abundant in the Windom member in the Finger Lakes area as well as further west. 

As might be expected, different lineages and species 

had different ecological requirements and tolerances.

MORPHOLOGIC TRENDS OF LINEAGES

Size increase in phyletic lineages has been cited as 

a common evolutionary trend (Newell, 1949). Inferred phylogenetic lineages of three genera, Leptotrypella, Atactotoeclius^ and Loxophragma, reveal a 

common tendency to progressive increase in size of 

the branches and lengths of the zooecia. Species of 

the three genera in the oldest member, the Centerfield 

limestone member of the Ludlowville, display branches 

relatively small in diameter and zooecia that contain 

relatively small maximum numbers of diaphragms in 

correspondingly narrow ephebic zones. Stratigraphically higher in the section the zoarial branches generally increase in diameter within individual lineages.

The increase in total diameter is largely a result of 

an increase in the diameters of the neanic zones that 

in turn are controlled by the number of zooecia in the 

branches. In addition to the increase in the diameters 

of the neanic zones, the ephebic zones show a general 

increase in their maximum widths and the maximum 

numbers of diaphragms. These general size increases

are conveniently expressed in the axial ratio the ratio 

of the neanic diameter to the total diameter. Since 

the increase of the neanic diameter is proportionally 

greater than the ephebic width increase in the lineages, 

and the total branch diameter consists of the ephebic 

width plus the neanic diameter, the axial ratios became larger with time. The axial ratio is still more 

useful if plotted against the corresponding number of 

zooecial diaphragms, a measure of the growth stage of 

the individuals in a colony, to form scatter diagrams.

The Leptotrypella mesostena-multitecta lineage (p. 

52) demonstrates such a size increase. Figure 24 

shows the maximum number of diaphragms of L. 

mesostena to be 7, the maximum number of diaphragms 

for L. multitecta is 12. The shift to the left in the 

diagram of the plotted points from L. mesostena to 

L. multitecta reflects the size increase in the lineage. 

Parallel increases occur in the L. mesostena-L. amphelicta lineage (p. 63) and the Loxophragma leptum-L. 

lechrium lineage (p. 79, fig. 27). The same shift to 

the left of the axial ratios is revealed in figure 26 for 

the Atactotoeclius acritus-A. hystricosus lineage. However, the intervening species, A. parallelus developed a 

slightly higher number of diaphragms than the species 

from the Windom so the gradual increase in the maximum number of diaphragms with time is not strictly 

followed in this lineage, according to the data presently available.

Some of the morphologic characters developed in 

species of Leptotrypella (Pycnobasis) (p. 62) approach characters typically found in Atactotoeclius 

(p. 69) and Loxophragma (p. 78), two genera that 

probably belong in a different family. The compound 

structure and the configuration of the diaphragms 

that appear in L. (Pycnobasis) are considered an example of parallel evolution. Aside from this similarity with the diaphragms of Atactotoeclius and 

Loxophragma there are no morphologic characteristics 

to indicate possible phylogenetic connections between 

the subgenus L. (Pycnobasis) and the two atactotoechid genera.

COMPARISON OF TREPOSTOMATA FROM HAMILTON 

AND TRAVERSE GROUPS

The only Middle Devonian trepostome fauna thoroughly studied using thin sections is that of the 

Traverse group of Michigan (Dimcan, 1939). The 

New York and Michigan faunas are so different in 

named species that little or no detailed stratigraphic 

correlations can presently be established between the 

two areas on the basis of comparable assemblages. 

The lack of species common to the two stratigraphic 

groups is no doubt explained in large part by differing 

age. The Devonian correlation chart (Cooper, 1942)
16

Collection

(20)

(35)

(52)

250B

260C

1006

1011

(39), 3500

3501

1017, 3502

275A, 3503

3505

3508

280, 3509

1015,3511

1014,3512

3513

3514

3515

3516

351S, 3519

3524

3526

3528

277A, 3528a

3529

3531

3532

3534

3539

3541

3542

3543

3545

3547

3547a

3548

3551

3552

3553

3555

3555a

3556

3558

3558a

3559

3561

3562

Locality 

number 

on map

(fig. 6)

30

19

16

9

1

14

18

22

24

3

17

2

12

6

4

8

15

6

7

9

10

11

13

15

15

15

16

16

18

20

20

19

25

21

26

26

23

27

27

27

28

28

28

32

32

32

31

41

Stratigraphic unit 

(member of Ludlowville shale and Moscow 

shale, as shown on 

fig. 2)

Upper Wanakah

Kashong

Windom

Tichenor

Tichenor

Centerfield

Upper Wanakah

Kashong

Kashong

Wanakah-P

Centerfield

Wanakah-P

Kashong

Wanakah-d

Wanakah-d

Wanakah-d

Wanakah-P

Wanakah-d

Wanakah-P

Wanakah-P

Upper Wanakah

Wanakah-P

Wanakah-P

Centerfield

Kashong

Centerfield

Kashong

Wanakah-d

Upper Wanakah

Centerfield

Ledyard

Kashong

Kashong

Upper Wanakah

Wanakah-P

Centerfield

Windom

Portland Point

Kashong

Windom

Wanakah-P

Deep Run

Kashong

Kashong

Wanakah

Windom

Centerfield

Windom

Gc

EX -S5 

*S

wtoechus

&

£

X

d

CO

d

-T

03 

G H

polymorphum Boa ma 

e

EX 

"§

I

Q

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

dCO

d

d

ro? senticosa Boardm

 jg"s 

e

o

^

T

"cs 

s

o 

VS

o

U

e

o '$

X

X

X

X

X

ffi

er\

decipiem

X

X

X

X

X

X

X

X

X

Boardman, zum n. sp

elasmatit

X

X

T

variacellus (Hall) s 

'-hytoechu

o

^

X

X

X

X

d

co

'.otrypella

.~

§

X

dCO £\

CO

C

d 

a

e-a 

a

0

PQ

'.mesostena 

EX

"o

 *^>

EX

3

T

dCO

CO

C

Boardman provecta a 

mesosten

T

Boardman. a n.sp.

multitect

X

X

X

X

X

X

X

X

T

X

X

Boardman, sp. n. 

asterica

X

X

X

X

X

T

X

X

X

"08

w

furcata (

X

X

X

T

X

(Grabau) ns 

 3

"EX 

8

C3

X

X

X

X

Boardman, rta sp. n. 

magnipo

X

X

X

Boardman, ;ta n. sp.

_ w

S

e

X

X

T

V.

Boardman, ragma n.

pachyph'i

X

Boardman, sp. n. 

tuberata

X

d

CO

d 

C

 c

O

PQ

jS

"S

EX

T

d

CO

d 

c

c

asphinctus Boardn us 

cylindric

 ^

£

X

X

T

X

Boardman, sp. n. 

oo

X

X

X

X

T

X

a

CO

acritus Boardman, n

totoechus

^

^

X

X

X

X

X

X

T

c

£

Boardman, rtus n. su

c

CO

e

X

T

o.

CO

£

Boardman, latus n. s

00

"S 

e

X

X

X

X

X

T

X

Boardman, sp. s n. 

parallelu

Boardman, n. sp. us 

hystricos

"5

W

00

fruticosu

X

X

X

X

a

CO

Boardman, leptum n

phragma

j

X

T

Boardman, sp. n. 

lechrium

X

X

X

X

X

X

X

X

X

X

X

X

T

X

X

X

X

X

X

X

X
EVOLUTION 17

Collection

3563

3564

3565

3567

3569

3570

3571

3572

3575

3579

3581

3582

3585

3586

3593

Locality 

number 

on map 

(fig. o)

42

42

5

42

40

43

36

36

37

38

34

33

29

28

35

Stratigraphic unit 

(member of Ludlowville shale and Moscow 

shale, as shown on 

fig. 2)

Portland Point

King Ferry

Wanakah-P

Windom

Windom

Windom

Centerfield

King Ferry

Windom

Windom

King Ferry

King Ferry

Windom

Tichenor

Centerfield

S. otoechus cf. Duncar typicus 

S

$

ft

CO

C

03

'O

s~

dophragma polymorphum Boa

S

Q

T

X

X

X

ft

co

c"

03

canlhopora? Boardm; senticosa 

"e

O

(Hall). "lema confertiporum 

 ra

3

ffi 

CO

e

S,

1

X

X

ft

co

c

03 

S

t,

03 

O 

PQ

s 

"e

CO

-2

hytoechus (Hall) variacellus 

e

^

X

otrypella sp-.

'I

^

ft

CO

3

CO

C

o3

-C

O

00

otrypella 1mesostena 

U

3

X

X

ft

CO

3

CO

C

Boardman, mesostena provecta Boardman, multitecta n. sp.

X

X

X

Boardman, asterica n. sp.

X

X

*03

w

.g "e

X

X

X

X

X

(Grabau) amplectens 

X

Boardman, magniporta n. sp.

T

X

Boardman, amphelicta sp. n. 

X

ft

co

Boardman, pachyphragma n.

T

Boardman, tuberato sp. n. 

T

Boardman, polita sp. n. 

ft

CO

C

3n

cylindricus Boardn asphinctus 

-2s

£

X

Boardman, clausus n. sp.

X

X

ft

co

Boardman, totoechus acritus n

u

.g

^

X

X

ft

CO

 **

Boardman, cartus n. su

ft

CO

.0

3

Boardman, pilatus cartus sn. Boardman, parallelus n. sp.

T

Boardman, hystricosus sp. n. 

T

(Hall) fruticosus 

X

X

X

X

ft

co

Boardman, leptum iphragma n

«

8

Boardman, lechrium n. sp.

X

X

X

Wanakah-d = »S. demisva zone

zone

indicates that the Centerfield limestone and Wanakah 

shale members of the Ludlowville shale are the only 

trepostome-bearing members of formations in the 

Hamilton that have time and rock equivalents in the 

Traverse group.

Comparison of the Traverse and Hamilton faunas 

at the species level reveals only one species now considered to be common to both groups. Leioclema decipiens (Hall) is considered to be conspecific with L. 

traver sense Duhcan and L. attenuatum Duncan (see 

p. 47). Unfortunately, L. decipiens is a fairly long 

ranging species in the Hamilton group, occurring in 

the Wanakah and King Ferry shale members of the 

Ludlowville shale and the Kashong member of the 

Moscow shale. The holotype of L. traversense comes 

from the Norway Point formation, which is correlated 

with the Wanakah member, and the holotype of L. 

attenuatum comes from the Potter Farm formation, 

which is considered, to be slightly younger than the 

Windom member at the top of the Hamilton group.

T=type locality.

The lack of trepostome species common to both the 

Traverse and Hamilton groups is paralleled by a 

similar lack of common species in the brachiopod 

fauna (G. A. Cooper, oral communication, 1956). 

In addition to different ages for some of the stratigraphic units of the 2 groups, differences of environment or partial or complete physical separation of 

the 2 basins could have contributed to the faunal 

differences.

Measurements (p. 53 and fig. Zl] of the holotype 

specimen of the species of Leptotrypella described by 

Duncan (1939) from the Traverse group of Michigan 

give a preliminary indication that branch size defines 

stages of evolution that have some time significance 

in the Traverse as well as in the Hamilton groups. 

All of the Traverse species of Leptotrypella come 

from formations now considered equivalent to the New 

York Skaneateles shale (Cooper, 1942). The table 

(p. 53) indicates that neanic diameters are generally 

comparable to those of L. mesostena mesostena, the sub-
18 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

species occurring in the Centerfield limestone member 

at the base of the Ludlowville shale, and are noticeably 

less than the neanic diameters of specimens from the 

younger Ludlowville species. Figure 24 indicates the 

older Michigan species generally developed more advanced growth stages than Centerfield species, but 

otherwise developed approximately the same evolutionary level, as expressed by diaphragm-axial ratio 

plots.

REGISTER OF LOCALITIES

The following is the list of collection numbers in 

numerical order. Opposite each is the appropriate 

locality number that appears on the index map '(fig. 

6). All collections except the first 14 were made by 

the writer and the identifying numbers refer to the 

Silurian-Devonian catalog of U. S. Geological Survey 

collections. U.S. National Museum collection numbers are those marked by asterisks. Collections 

marked with one asterisk were made by G. A. Cooper, 

those marked with two asterisks were made by A. R. 

Loeblich, Jr., and I. G. Reimann.

USNM and Geological Survey No. on 

collection numbers figure 6

(20)*. ..._-.......... 30

(35)*. _......._..__.. 19

(39)*.. ...-..._...... 22

USNM and Geological Survey No. on 

collection numbers figure 6

3534.

250B*.

260C*

275A*.

277A*.

280*...

1006**.

1011**.

1014**

1015**.

1017**

3500...

3501...

3502... 

3503_-- 

3505___

3508...

3509. -.

3511...

3512... 

3513-. 

3514... 

3515_..

3519- 

3524. 

3526.-

3528a_ 

3529. _

3531..

3532..

9

1

17

15

6

14

18

a

4

3

?,?,

?A

3

17

?,

1?

6

4

8

15

6

7

9

10

10

11

13

15

10 

i ^

16

16

3543--_---._---------

3545.. _______________

3547. .... ------------

3548----------------

3551. -.-... ----------

3552... ....... -------

3553---. -------------

3555.. ---------------

3556-------------.---

3558.. ---------------

3559. _. --------------

3561. .... ------------

3562--.----..------..

3563.. ---------------

3564--_. -_-------_-.-

3565. _-_--.--._-----

3567.. ........ .-._---

3569.. ---------------

3570.. . --------------

3571. ----------------

3572---_. -__. --------

3575-. ______________

3579__. .-----_--. .---

3581. .---_-. ---------

3582__. -----_-----.-.

3585--------------..

3586---.------------.

3593..-..-----.------

18

20

20

19

25

21

26

26

23

27

27

27

28

28

28

32

32

32

31

41

42

42

5

42

40

43

36

36

37

38

34

33

29

28

35

No. on Geological Stratigraphic unit 

figure 6 Survey (member of Ludlowville 

(map collection shale or Moscow shale, 

locality number as shown on fig. S) 

number)

Description

1 260C Tichenor.

2 3505 Wanakah,

Pleurodictyum 

zone.

3 1017, Wanakah,

3502 Pleurodictyum 

zone.

4 1015, Wanakah,

3511 S. demissa 

zone.

5 3565 Wanakah,

Pleurodictyum 

zone.

280, Wanakah, 

3509 S. demissa 

zone.

3514 Wanakah,

S. demissa 

zone.

7 3515 Wanakah,

Pleurodictyum 

zone.

8 1014, Wanakah,

3512 S. demissa zone.

9 250B Tichenor........

3516 Wanakah.

Pleurodictyum 

zone.

10 3518, Wanakah 

3519 (Upper).

Eighteen Mile Creek, west 

of railroad, Eden quadrangle, Erie County.

Road cut and bare interfluvial area between state 

route 75 and Morse Creek, 

and just southeast of 

railroad underpass. 

Morse Creek is just south 

of Athol Springs, Buffalo 

quadrangle, Erie County.

Shale pit between Big Tree 

Road and first creek 

north of Athol Springs, 

and just southeast of 

railroad, Buffalo quadrangle, Erie County.

Railroad cuts paralleling 

Rush Creek 0.5 mile 

north of Big Tree Road, 

Buffalo quadrangle, Erie 

County.

Large quarry just west of 

railroad tracks and 0.5 

mile north of Bay View, 

Buffalo quadrangle, Erie 

County.

South branch of Smoke 

Creek at Windom, Buffalo quadrangle, Erie 

County.

Tributary of south branch 

of Smoke Creek at Windom. Tributary just 

north of northeast corner 

of Windom. Buffalo 

quadrangle, Erie County.

South branch of Smoke 

Creek, downstream approximately 0.5 mile from 

locality 6.

North Branch Smoke Creek, 

northeast of Windom 1.25 

miles at Berg Road, 

Buffalo quadrangle, Erie 

County.

Cazenovia Creek, at Transit Road bridge, 1.5 miles 

northwest of Spring 

Brook, Depew quadrangle, Erie County.

North flowing tributary of 

Buffalo Creek between 

Bullis Road and railroad. Northeast of 

Spring Brook, 1.5 miles, 

Depew quadrangle, Erie 

County.
REGISTER OF LOCALITIES

78°

19

77 C

79° 78° 77°

FIGURE 6. Map of western and central New York showing the outcrop location of the Hamilton group, and the collecting localities.

No. on 

figure 6 

(map 

locality 

number)

11

Geological 

Survey 

collection 

number

3524

12 3508

13 3520

Stratigraphic unit 

(member of Ludlowville 

shale or Moscow shale,

as shoiun on fig. 2)

Description

Wanakah, Pond Brook, a tributary of

Pleurodidyiim Buffalo Creek. South of

zone. Elma 0.25 mile, Depew

quadrangle, Erie County.

Kashong._______ West flowing tributary of

Cayuga Creek, 1.25 miles 

SSE of West Alden, 

Depew quadrangle, Erie 

County.

Wanakah, Eleven Mile Creek, 1.1

Pleurodictyuin miles north of route 20

zone. at fork in stream. Eleven

Mile Creek is 1.7 miles

west of Darien Center,

Attica quadrangle, Genesee County.

No. on 

figure 6 

(map 

locality 

number)

14

15

Geological Stratigraphic unit

Survey (member of Ludlcwville

collection shale or Moscow shale,

number as shown on fig. 8)

Description

1006 Centerfield___-__- Crooked Creek, 0.5 mile

south of railroad and 1.25 

miles west of North Darien, Attica quadrangle, 

Genesee County.

3513 Wanakah, Murder Creek; Centerfield 

Pleurodiclyum outcrops 1.2 miles north 

zone. of Darien just west of

3528 Centerfield school, J4 mile south of 

3528a, Kashong road intersection; Wana277A kah is north of Darien

0.5 mile, just south of 

stream intersection with 

northwest trending road; 

Kashong is just south of 

Darien. Attica quadrangle, Genesee County.
20 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

'No. on Geological 

figure 6 Survey 

(map collection 

locality number 

number)

Stratigraphic unit 

(member of Ludlowville 

shale or Moscow shale, 

as shown on fig. S)

Description

15 3529 Centerfield.

16 (52) Windom

(Upper).

17. 275A, Centerfield. 

3503

18 1011 Wanakah 

(Upper).

18 3534 Wanakah 

(Upper).

19 3542 Kashong.

19 (35) Kashong.

20 3539 Centerfield. 

3541 Ledyard

21 3545 Wanakah 

(Upper).

22 (39), Kashong. 

3500

Field exposure, just north 

of eastwest trending 

road, 0.75 mile E.N.E. 

of Murder Creek exposure of Centerfield.

Bowen Brook, 1000 paces 

south of bridge (upstream) 1 mile south of 

Ray and northwest of 

Alexander, Attica quadrangle, Genesee County.

Exposure just north of D. 

L. and W. railroad tracks 

at milepost 357, 2.5 miles 

east of East Alexander, 

Batavia quadrangle, 

Genesee County.

Road cut, 3.8 miles northwest of Pavilion, Batavia 

quadrangle, Genesee 

County. (Shaly lower 

beds 5' below limestone).

Roadside exposure, 1.5 

miles southeast of East 

Bethany, at the intersection of Stafford-Wyoming road and White 

Creek. Just east of 

locality 1011.

Shale pit just west of intersection of White Creek 

and route 20, 3 miles east 

of Bethany, Batavia 

quadrangle, Genesee 

County.

White Creek; Kashong outcrops in Creek at intersection with route 20, 

just east of collection 

3542.

White Creek; Centerfield 

outcrops just south of D. 

L. and W. Railroad and 

west of Stafford-Wyoming Road. Ledyard 

outcrops just upstream.

East flowing creek at intersection with north-south 

road, 1.2 miles west of 

York, Caledonia quadrangle, Livingston 

County.

Dump of salt company, 0.5 

mile southeast of Greigsville, Caledonia quadrangle, Livingston 

County.

No. on 

figure 6 

(map 

locality 

number)

Geological Slratigraphic unit

Survey (member of Ludlowville

collection shal-e or Moscow shale,

number as shown on fig. S)

Description

23 3548 Windom.

24 3501 Kashong.

25 3543 Kashong.

26 3547 Wanakah,

Pleurodictyum 

zone. 

3547a Centerfield

27 3551 Portland Point..

3552 Kashong

3553 Windom

28 3555 Wanakah,

Pleurodictyum 

zone. 

3555a Deep Run

3556 Kashong 

28 3586 Tichenor_...--_.

29 3585 Windom.

30 (20) Wanakah 

(Upper).

31 3561 Centerfield.

32 3558 Kashong..

3558a Wanakah

3559 Windom

Pearl Creek, west of railroad approximately 0.25 

mile. Straight north of 

Leicester 1.7 miles. Caledonia quadrangle, Livingston County.

Little Beards Creek, 1 mile 

NNE of Leicester at 

farmhouse east of Leicester-Greigsville highway. 

Caledonia quadrangle, 

Livingston County.

Fall Brook, 1.5 miles SSW 

of Genesee, section just 

east of Genesee-Cuylerville road. Caledonia 

quadrangle, Livingston, 

County.

Jaycox Run, 2.3 miles 

north of Genesee, below 

falls, Caledonia quadrangle, Livingstor 

County.

Menteth Creek, 5.5 miles 

south of Canandaigua, 

west side of Canandaigua 

Lake, Canandaigua quadrangle, Ontario County.

Deep Run, 1 mile north of 

Cottage City, east side 

Canandaigua Lake, Canandaigua quadrangle, 

Ontario County.

Creek at Green's Landing, 

0.5 mile north of Deep 

Run.

Creek at Goodings Landing, 0.8 mile south of 

Cottage City, east side 

Canandaigua Lake, Canandaigua quadrangle, 

Ontario County.

Fall Brook, 3 miles ESE of 

Canandaigua, C a n a ndaigua quadrangle, Ontario County.

Wilson Creek, 4 miles south 

of north end of Seneca 

Lake, on west side of 

lake, Geneva quadrangle, Ontario County.

Kashong Creek, 7.5 miles 

south of north end of 

Seneca Lake, west side of 

Lake, Geneva quadrangle, Ontario and Yates 

Counties.
REGISTER OF LOCALITIES 21

No. on 

figure 6 

(map 

locality 

number)

Geological Stratigraphic unit

Survey (Member of Ludlowville

collection shale or Moscow shale,

number as shown on fig. £)

Description

33 3582 King Ferry.

34 3581 King Ferry.

35 3593 Centerfield.

36 3571 CenterfiekL 

3572 King Ferry

37 3575 Windom.

38 3579 Windom.

Big Hollow Creek, west 

side of Cayuga Lake, 4.5 

miles NE of Ovid, Ovid 

quadrangle, Seneca 

County.

Sheldrake Creek, west side 

of Cayuga Lake, 3 miles 

NNE of Interlaken, 

Genoa quadrangle, Seneca County.

Gould's Falls, creek just 

north of Aurora, east side 

Cayuga Lake, Auburn 

quadrangle, Cayuga 

County.

Paines Creek, east side 

Cayuga Lake, 1 mile 

south of Aurora. Centerfield at Moonshine Falls, 

King Ferry at Black 

Rock. Genoa quadrangle, Cayuga County.

Clearview Creek, King 

Ferry Landing, east side 

Cayuga Lake, Genoa 

quadrangle, Cayuga 

County,

Taughannock Falls, west 

side Cayuga Lake, 2.5 

miles ESE of Trumansburg, Genoa quadrangle, Seneca County.

Tributary of Salmon Creek, 

northernmost of the two 

west flowing tributaries 

at Ludlowville, Genoa 

quadrangle, Tompkins 

County.

Quarry of the Penn-Dixie 

Portland Cement Company. 0.75 mile southwest of South Lansing, 

east side of Cayuga Lake, 

Genoa quadrangle, 

Tompkins County.

Portland Point or Nortons 

Landing on Cayuga Lake, 

1.1 miles southwest of 

South Lansing, Genoa 

quadrangle, Tompkins 

County.

Fillmore Glen, in Fiiimore 

State Park, 1 mile south 

of Moravia, Moravia 

quadrangle, Cayuga 

County.

GLOSSARY

The bryozoan terminology used in this paper is 

largely defined by R. S. Bassler in the "Treatise on

40 3569 Windom.

41 3562 Windom.

42 3563 Portland Point. .

3564 King Ferry

3567 Windom

43 3570 Windom.

Invertebrate Paleontology, part G, Bryozoa, p. G7 

to G16." Additional terms and variant usages are 

denned below.

Amalgamate ivall structure or appearance. Term 

used for zooecial walls as seen in tangential section in 

which the zooecial boundaries are not visible and the 

positions of these boundaries are marked by relatively 

broad bands of apparently nonlaminated skeletal material. (Fig. 8 and pi. 11, fig. 3a.)

Atactotoechid wall structure. See p. 32.

Axial Ratio.^R&tio between neanic diameter and 

total branch diameter.

Compound diaphragm. Diaphragm formed by two 

or more simple diaphragms that are in contact most or 

all of the way across a zooecium. (PL 21, figs. 1-3.)

Cyst. Small, hollow, subspherical body occurring 

within the zooecial cavity and composed of laminated 

material that is continuous with the laminae of supporting diaphragms or zooecial walls. (PL 10, fig. 4.)

Cystiphragm. Skeletal partition extending from 

the zooecial wall into the zooecial cavity and recurved 

proximally to form a closed compartment by abutting 

against the zooecial wall or adjacent cystiphragm or 

diaphragm. Cystiphragms either partly or completely 

encircle the zooecial cavity to form a hollow ring and 

commonly occur in closely packed or overlapping series 

lining the zooecial cavities. Cystiphragms do not extend completely across the zooecial cavity. (PL 17, 

% 5.) _ Cystoidal diaphragm. A transverse structure 

formed by two diaphragms in contact only part way 

across the zooecial cavity to form a completely enclosed compartment between them. At least one of 

the partitions is a complete diaphragm. (PL 20, fig. 

4b.)

Diaphragm. Skeletal partition extending transversely across the zooecial tube or mesopore.

Diaphragm-wall unit. The diaphragm and that 

part of the distally adjacent zooecial wall that are 

directly connected to form a continuous skeletal unit. 

(Fig. 8.)

Ephebic zone. Part of individual and colony possessing most of the taxonomic structures. In the 

Trepostomata, the ephebic zone consists of the outer 

parts of zooecia and zoaria characterized by thickened 

zooecial walls, relatively abundant diaphragms, and 

mesopores and acanthopores, if present. Synonymous 

with mature region of authors. See figure 7.

Hemiphragm. Shelf-like platform in the ephebic 

part of zooecial tube, joined to the walls on the proximal side only and extending part way across the tube. 

The platform consists of laminae that are continuous 

with the laminae of the zooecial walls. (Fig. 22.)

50S925 O GO-
22 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

Zooecial surface 

\angle ,

-Zoecium with 

4 diaphragms

Diameter of zoarium 

Width of ephebic zone 

.Width of neanic zone

FIGURE 7. Diagrams Illustrating standard measurements. A., tangential section of a single zooecium ; B, longitudinal section of ramose 

zoarium.

Independent wall unit. A segment of the zooecial 

wall that is not connected to the laminae of a diaphragm. (Fig. 8.)

Integrate wall structure or appearance. Term used 

for zooecial walls as seen in tangential section in which 

zooecial boundaries appear as lines, either light or 

dark in shade. (PL 20, fig. 4a.)

Leioclemid wall structure. See p. 30.

Leptotrypellid wall structure. See p. 32.

Longitudinal section. Section exposing the zooecia 

parallel to their length. In a ramose zoarium the 

plane of the section is in the center of the branch, 

parallel to branch length. In a massive or incrusting 

zoarium the plane of the section is perpendicular to 

the surface of the zoarium.

Measurements. Numbers of zoaria included in the 

table of measurements for a species commonly are 

fewer than the total number of zoaria of that species 

available for study. In species in which few zoaria 

were available, these discrepancies were caused by 

orientations of thin-sections that were oblique enough 

to affect or make impossible the measurements. Precise orientation of thin-sections is especially difficult 

in irregularly massive or incrusting forms, and in 

zoaria that can not economically be freed from the 

matrix. In species in which many zoaria were available, it was considered not necessary to measure sections from all of the zoaria.

Megazooecium. An enlarged zooecium developed in 

the monticules. (PL 12, fig. Yb.)

Mesopore. Skeletal sac or tube, parallel to the 

zooecia but appreciably smaller in diameter and in 

most genera limited to the ephebic zone. Included 

diaphragms are generally more closely spaced than 

those in zooecia. (PL 2, figs. 2 and 5.)

Monticule. Clusters of modified zooecia (generally 

megazooecia, mesopores, and acanthopores in different combinations) regularly spaced throughout a 

zoarium and appearing on the surface generally as 

small protuberances. (PL 11, fig. 3b; pi. 12, fig. Yb; 

pi. 14, fig. 2b.)

Mural lacuna. Small equidimensional void in zooecial walls. (PL 11, fig. 3a.)

Mural spine. Small laminated spine continuous 

with the laminae of the surfaces of zooecial walls and 

diaphragms and projecting into the zooecial cavity. 

(PL 8, figs. 4, 5a, and 6.)

Neanic zone. Part of individual and colony too undeveloped to possess many taxonomic characters. In 

the Trepostomata the neanic zone consists of the basal 

or inner part of a zooecium and zoarium, characterized 

by thinness of zooecial walls and relative sparseness or 

absence of transverse structures. Synonymous with 

immature region or axial region of authors (fig. 7).

Overgrowth. Conspecific secondary growth incrusting a zoarium and separated from the zoarium by a 

basal lamina. (PL Y, fig. 4a.)

Stereotoechid ivall structure. See p. 30.

Tangential section. Section parallel to and just 

under the surface of a zoarium. The section normally 

cuts the zooecia transversely.

Transverse section. Section at right angles to the 

branch of a ramose zoarium.

Trachytoechid' wall structure. See p. 31.

Zoarium. The collective skeletal parts of a bryozoan colony.

Zone of curved laminae. That part of the zooecial 

wall characterized by strong curving of the laminae as 

seen in longitudinal section. The laminae in the zone 

are continuous with the distal ends of the laminae of 

the diaphragms, or zooecial lining if present, and end 

at the zooecial boundary. (PL 10, fig. la.)

Zooecial bend. Relatively sharp bend in the zooecium generally located either at the boundary between
GLOSSARY 23

the neanic and ephebic zones or in the early ephebic 

zone. The concave side of the bend is always toward 

the proximal direction of the zoarium. (PI. 6, fig. 8c.)

Zooecial boundary. Narrow zone in which the wall 

laminae from adjacent zooecia merge or abut against 

each other. (PI. 17, fig. 6a.)

Zooecial lining. A zone in a zooecial wall consisting 

of the laminae that line a zooecium and trend parallel 

to the longitudinal direction of the zooecia for a considerable distance. The zone is continuous proximally 

with the laminae of the diaphragms and distally with 

the zone of curved laminae. (Fig. 12 and pi. 15, figs. 

3a, 4.)

Zooecial surface angle. The acute angle at which 

the zooecia intersect the surface of the zoarium. 

(Fig. 7.)

Zooecium. Skeletal sac or tube that contained the 

soft parts (polypide) of the whole animal or zooid.

MORPHOLOGY AND TAXONOMY

The devising of a satisfactory classification of the 

trepostomatous Bryozoa is seriously handicapped by 

our complete ignorance of the living animal. The biologic significance of structures occurring in the order 

is speculative, consequently the taxonomic principles 

that can be applied to this large extinct group are 

limited. Most skeletal structures must be treated 

empirically and evaluated by indirect means. These 

indirect approaches provide the basis for many of the 

practical and usable features of the classification, but 

by themselves are likely to result in a high degree of 

artificiality.

The extent to which a natural classification of the 

Trepostomata can be established will depend on how 

much success students have in using biologic principles 

to substantiate and modify the largely artificial classification. The attainment of a natural phylogenetic 

classification throughout is an impossible goal; but a 

generally satisfactory classification, in part phylogenetic, and based on biologic principles whenever 

possible, should be attainable by careful study.

In establishing taxonomic criteria indirectly, the 

value of a character commonly is judged by its constancy in a number of forms. That is, a structure or 

characteristic that occurs throughout a group of obviously diverse forms is generally given a more important taxonomic role than another structure or 

characteristic that is seen in only a quarter of the 

forms. The reliability of a character is strengthened 

if it is associated with other characters that occur in 

the same grouping of specimens.

It happens commonly that there is a negative correlation between morphologic characters that are approximately equal in numbers of occurrence. Such

negative correlations result in different groupings, depending on which character is given preference. It is 

then necessary to accept one character as most important and downgrade the others in order to present 

a single taxonomic arrangement. Purely subjective 

suppression of certain taxonomic characters is certainly not a sound basis for a natural classification.

If established biologic principles can be applied to 

problems of taxonomic evaluation, many preferential 

decisions can be made with the hope of approximating 

the natural grouping. In the Trepostomata, the study 

of complete zoaria contributes to the understanding of 

ontogeny, polymorphism, and mode of colonial 

growth. Distributional studies in time and space furnish data for the evaluation of more realistic species 

concepts. These distributional studies are based on 

the essentially nondimensional collections that provide 

data on morphologic variation in inferred population 

samples, and superimposed collections from single 

localities that give relative time relationships. Geographic distribution and paleoecologic interpretations 

complete the distributional data. These and other 

biologic principles are essential factors in inferring 

eA^olutionary trends and patterns and developing a 

more nearly natural, phylogenetic classification.

Study of the Trepostomata is separable into two 

periods based on techniques and approach used in 

morphologic and taxonomic investigations. Students 

in the earlier period mainly observed growth habits 

of the zoaria and details of external appearance. The 

second period is marked by the additional study of 

internal features of the zoaria by means of thin sections, and the increased importance of the zooecia in 

the classification. The more recent approach has 

shown the earlier work to be ineffectual and misleading in both biologic and strati graphic applications. 

Growth habits of the zoaria are now considered of 

minor taxonomic importance in the Trepostomata, for 

zoaria that are similar in growth habit and external 

appearance are known to differ conspicuously in microscopic internal structure. The current classification 

of the order is based on internal characters and external homeomorphy is generally an important factor 

in the study of Trepostomata.

The Trepostomes have "stony" and massive zoaria 

rather than the "mosslike" skeletons that are characteristic of many living bryozoans. Consequently, trepostomes were relegated to the coral group when the 

Bryozoa was first recognized in 1830 by Thompson 

(Polyzoa) and in 1831 by Ehrenberg (Bryozoa). In 

the latter half of the nineteenth century an active
24 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

controversy arose concerning the zoological affinities 

of the trepostome group. The arguments on both 

sides were confused because of poorly defined concepts of taxonomic groups called the "favositids," 

"monticuliporoids," "stenoporoids," "chaetetids," and 

"trepostomes." At one time or another, all of these 

groups contained both bryozoans and corals in varying 

proportions depending on the prejudices of individual 

authors. When thin-section studies were first introduced, many structures were misinterpreted. Certain 

genera were declared to be "truly" corals or bryozoans 

on erroneous grounds. These genera were then used 

as standards for comparison with related genera, and 

all were designated either corals or bryozoans.

In 1876 Nicholson (p. 85-95, pi. 5) published what 

are probably the first illustrations of thin sections of 

Bryozoa. Nicholson followed this paper by a series 

of outstanding publications that established ,the need 

for thin sections, and recognized the major internal 

structures subsequently used in the modern classification of the trepostomes, or monticuliporoids as they 

were then known. Nicholson recognized the minor 

taxonomic value of zoarial growth habit (1879, p. 273) 

and the occurrence of apparently dimorphic individuals in the zoaria (1879, p. 276). He correctly described the structure of acanthopores (1879, p. 278) 

and distinguished inner thin-walled zones and outer 

thick-walled zones in the zoaria (1881, p. 31).

Nicholson was probably the leading advocate of 

the view that the affinities of the monticuliporoids were 

with the corals rather than with the bryozoans. One of 

his main arguments favoring coral affinities was the belief that the bryozoan genus Stenopora Lonsdale had 

mural pores and was an undoubted favositid coral (1879, 

p. 173). As comparisons between the monticuliporoids 

and Stenopora were convincing and valid, he considered all of the monticuliporoids to be tabulate corals. 

However, his discussion indicates he experienced some 

difficulty in interpreting the wall structures in thin 

sections. Waagen and Wentzel (1886, p. 886) pointed 

out that Nicholson was working with imperfect material in which the actual walls had been removed by 

solution, leaving internal molds of the zooecia. Thus, 

the presence of mural pores actually could not have 

been determined. Nicholson subsequently (1889, p. 

350) accepted the interpretation of Waagen and Wentzel and placed Stenopora, with the monticuliporoids, 

but remained uncertain as to the affinities of the general group.

Waagen and Wentzel (1886, p. 855) and G. R. Vine 

(1884, p. 182) agreed with Nicholson on the coralline 

affinities of monticuliperoids. Waagen and Wentzel 

attempted to develop a line of argument in favor of

corals based on the mode of propagation of the individuals in colonies. Their description of gemmation 

in monticuliporoid zoaria assumed that mesopores and 

acanthopores are not polymorphic individuals but 

merely young zooecia in the initial stages of formation. This concept has not been subsequently substantiated.

The first attempt to assign the general trepostome 

group to the bryozoans probably was made by Rominger of Michigan (1866, p. 1-3). He compared some 

of the genera now included in the Trepostomata with 

the genus Heteropora, a post-Paleozoic form that he 

considered transitional between Paleozoic trepostomes 

and undoubted bryozoans. Heteropora was mentioned 

throughout the controversy by other authors also, procoral advocates either denying morphologic similarities with the trepostomes or arguing that Heteropora 

was not a bryozoan.

In 1873 Dr. Gustav Lindstrom published a paper 

on the affinities of the Anthozoa Tabulata in the Proceedings of the Swedish Academy of Science, later 

translated (1876, p. 1-17), in which he cited Rominger's work and placed a number of the known genera 

of trepostomes in the Bryozoa. Lindstrom was one 

of the first to use astogeny as an approach toward 

answering the question. He claimed that as a colony 

developed from the first few cells it passed morphologically from one "genus" to the next, as genera were 

then defined. Further, he claimed he could trace mature colonies of trepostomes back to initial stages that 

belonged to genera of undoubted bryozoans. Unfortunately, no illustrations were published and stages 

of development were defined by comparing them with 

poorly understood genera. Lindstrom's work is difficult to evaluate and served only to heighten the 

argument. About the same time Dollfus (1875, p. 

681-683) and Zittel (1880, p. 575-641) placed the family Chaetetidae, then containing most of the trepostomes, in the Bryozoa.

In 1882 E. O. Ulrich began a series of publications 

that produced our present classification of the Paleozoic Bryozoa. Using the techniques and approach 

outlined by Nicholson, Ulrich established the suborder 

Trepostomata (Ulrich, 1882, p. 151) and began the 

first comprehensive study of the group. Ulrich agreed 

with Nicholson on the interpretation of many structural features but believed the group to be Bryozoa, 

comparing them with post-Paleozoic Cyclostomata, 

which were accepted bryozoans.

In 1902 E. R. Cumings began a series of definitive 

papers on early Paleozoic Bryozoa, presenting factual 

evidence that helps clarify many of the perplexing 

problems relating to the Trepostomata. Cumings made
MORPHOLOGY AND TAXONOMY 25

a detailed study of the initial stages in the development of zoaria belonging to the fenestellids and the 

monticuliporoids. He showed that the Cryptostomata 

and Trepostomata started zoarial growth in the same 

manner and that the development of bryozoan zoaria 

was radically different from that of typical tabulate 

corals (1912, p. 365). Cuming's observations have 

since been accepted as critical evidence bearing on the 

zoological affinities of the trepostomes and, added to 

the mass of morphologic comparisons, ended the controversy about the zoological relationships of the 

Trepostomata.

WALL STRUCTURE AND TAXONOMY 

PREVIOUS WORK

The early descriptions of zooecial wall structure by 

Nicholson were based on tangential views and were 

concerned largely with the amalgamate or discrete 

appearance between adjacent tubes, depending upon 

the presence or absence of a dark line marking the tube 

boundaries. The dark line was interpreted as the 

primordial wall (Nicholson, 1881, p. 37).

Nicholson's methods and his reliance on the tangential sections in interpretations of wall structure 

were perpetuated by Ulrich and later by Bassler. In 

1890 Ulrich published a monograph on the Paleozoic 

Bryozoa that is probably the most important single 

work on the trepostomes. The classification proposed 

is the basis for the one used today (Bassler, 1953, p. 

G91-G119). Wall structure of trepostomes in general was described. The line diAdding adjacent zooecia 

was termed the "primitive wall" (Ulrich, 1890, p. 310) 

and the material thickening the zooecial walls in the 

ephebic zones was called a "secondary deposit" (Ulrich, 

1890, p. 307).

Ulrich and Bassler published a revision of the 

Paleozoic Trepostomata in 1904. Two "divisions" of 

the trepostomes were recognized on the .basis of 

zooecial Avail structure as seen in tangential thin 

sections.

The classificatory value of the structure of the walls separating neighboring zooids, especially the degree in which the 

calcareous investment of adjoining zooids is either amalgamated or maintains for each its integrity, continues to impress us more and more favorably (Ulrich and Bassler, 1904, 

p. 15).

Accordingly, they divided the Trepostomata into the 

Amalgamate, including four families, and the Integrata, including three families.

The families currently recognized (Bassler, 1953) 

remain essentially unchanged since the 1904 revision. 

In 1911, Bassler published a paper on the early Paleozoic Bryozoa of the Baltic Provinces that best expresses the Ulrich-Bassler classification of the trepostomes. Wall structure \vas considered to provide 

fundamental criteria for family groupings (Bassler, 

oral communication 1952). The folloAving quotations 

taken from either the 1904 or 1911a papers summarize 

the published information on the Avail structures in 

their classification.

DIVISION I. AMALGAMATA, 1904

"Trepostomata in which the boundaries of adjacent zooecia 

are obscured by the more or less complete amalgamation of 

their walls" (Ulrich and Bassler, 1904, p. 15).

Family MONTICULIPORIDAE Nicholson (Emend. Ulrich)

The wall structure of the family is best expressed by a description of the type genus, as follows:

"The peculiar granulose walls, the vary slight development 

or total absence of the laminated secondary deposit * * *" 

(Ulrich and Bassler, 1904, p. 15).

Family HETEROTRYPIDAE Ulrich, 1890

"As seen in tangential sections of well preserved specimens, 

the wall separating adjacent zooids consists (1) of a moderately wide, light-colored, transversely dotted or lined, central 

band, which represents the amalgamated original walls, and 

(2) bordering it on each side, a concentrically laminated, 

secondary deposit" (Ulrich and Bassler, 1904, p. 23).

Family CONSTELLARIIDAE Ulrich in Zittel, 1896

"The most obvious characteristic of the family is the usually 

stellate shape of the maculae. More important features are 

the small, hollow spines or granules which occur in place 

of true acanthopores, and a somewhat granular wall structure 

occurring in the more mature portion of the zoarium" (Bassler, 

1911a, p. 218).

Family BATOSTOMELLIDAE Ulrich in Miller, 1889

"In this family the amalgamate nature of the zooecial walls 

is most marked, in fact so much so that adjoining walls 

usually appear as completely fused together" (Bassler, 

1911a, p. 240).

DIVISION II. INTEGRATA 1904

"Trepostomata in which the boundaries of adjacent zooecia 

are sharply defined by a black divisional line" (Ulrich and 

Bassler, 1904, p. 40).

"This line in all probability represents the fossilized remains of animal matter which filled this space during the 

life of the organism. Occasionally, this narrow, intervening 

area is occupied by a light-colored tissue, and in this case 

the outer boundaries of the walls of each zooeciuin can be 

seen." (Bassler, 1911a, p. 177).

Family AMPLEXOPORIDAE Ulrich in Miller, 1889

"The simplest types of Integrata are included in this family, 

which, because of this simplicity as well as the practical 

absence of mesopores, shows the duplex character of the 

walls most distinctly" (Bassler, 1911a, p. 265).

Family HALLOPORIDAE Bassler, 1911 

(emend. Calloporidae Ulrich, 1890)

"The family includes those integrate trepostomatous bryozoans in which the zooecial tubes are thin-walled and attain
26

their full size slowly, but chiefly in which acanthopores are 

absent" (Bassler, 1911a, p. 325).

Family TREMATOPORIDAE Ulrich in Miller, 1889 

"Walls thickened in the mature region, with a distinct divisional line where the zooecia are in contact. As a rule the 

Trematoporidae have a general looseness and slight obscurity 

of structure quite unlike that of any other family. For example, the walls are not as clear and distinct as in the 

Amplexoporidae or Halloporidae, the acanthopores have a less 

definite, clear cut structure, and the walls are often undulating" (Bassler, 1911a, p. 267).

In 1915 Cumings and Galloway published a significant paper on the morphology of the trepostomes. 

They found a species of the genus Heterotrypa (placed 

in the Amalgamata by Ulrich and Bassler) that displayed both an amalgamate and integrate appearance 

in tangential sections. This observation led them to 

study wall structure in longitudinal views using thinner sections and higher magnifications than had been 

previously employed. Cumings and Galloway (1915, 

p. 360) found that wherever wall laminae are sharply 

bent, the deposit appears darker. If the laminae 

intersect the boundaries at low angles they are most 

sharply bent at the zooecial boundaries. Cumings and 

Galloway considered the sharp bending of the laminae 

to be the origin of the dark "primary" wall exhibited 

in tangential sections and used to define the Integrata 

of Ulrich and Bassler. Also, (Cumings and Galloway, 

1915, p. 365)

the presence or absence of a dark median line in the wall 

depends to a large extent on the steepness of pitch of the 

laminae, which in turn depends on whether the growing edge 

of the wall is thin and sharp or blunt and smoothly rounded.

"Pitch of the laminae" was found to be variable within 

a species and even within a specimen (1915, p. 359). 

In evaluating the taxonomic use of the amalgamate 

and integrate appearance they state 

If the differences above described are due primarily to the 

steepness of pitch of the wall laminae, it is likely that the 

classificatory value of this phase of wall structure in the 

Trepostomata is also of subordinate rank (1915, p. 361).

Cumings and Galloway (1915, p. 361) interpreted 

the laminae lining the zooecial walls and extending 

into the diaphragms and cystiphragms to be secondary 

in origin.

The secondary deposits we have designated the cingulum, because in tangential sections * * * they give the appearance of 

a well denned ring or zone of deposits adjacent to the zooecial 

cavity.

G. W. Lee (1912, p. 145) also found difficulty with 

the amalgamate-integrate concept. He wrote:

In the British fauna, so far as examined, a black line is 

occasionally exhibited in forms which are otherwise referable 

to the division Amalgamata. Its adoption as a classificatory 

character in the case of the materials considered here would

lead to an inconsistent grouping of the species, and is therefore deferred pending further investigation.

Helen Duncan (1939, p. 186) had difficulty in placing the Traverse genera in the Ulrich-Bassler classification and proposed the family Atactotoechidae to 

include genera displaying both amalgamate and integrate structure. In discussing the genus Atactotoechus^ Duncan comments:

The fact that some species of Atactotoechus have integrate 

and others amalgamate walls does not seem to be an adequate 

reason for placing in different families forms having other 

homogeneous structural, characters.

WAJLL, STRUCTURE AND TAXONOMY IN THE HAMILTON 

TREPOSTOMATA

A study of the well-preserved Trepostomata from 

the Hamilton group of New York indicates that some 

genera cannot be placed in suborder and family categories as presently defined in the literature. Several 

species of both Atactotoechus and Leptotrypella show 

both amalgamate and integrate wall structure in tangential sections, the same condition also observed by 

Duncan in Traverse species, and by Cumings and Galloway, and Lee in trepostomes of other systems. Such 

variation within a species, and even within a zoarium, 

conflicts with the degree of constancy expected for 

usable subordinal characters.

The writer also had difficulty applying recognized 

criteria for families. Species of Leptotrypella in the 

Hamilton group do not have a "transversely dotted 

or lined, central band, which represents the amalgamated original walls" described as characteristic of the 

Heterotrypidae by Ulrich and Bassler. Rather, the 

"central band" in well preserved specimens ,of Leptotrypella appears to be structureless and hyaline in all 

but a few tangential sections. A few specimens exhibit uniformly spaced mural lacunae or rare clusters 

of irregularly spaced mural lacunae, that can be considered small "dots" but they are unknown in some 

species of Leptotrypella, and are interpreted as a 

species character at best in the genus.

A still more difficult problem is posed by the genera 

now referred to the family Stenoporidae (Bassler, 

1953, p. G101). No essential differences were seen between tangential thin sections of Hamilton stenoporid 

genera and sections of the heterotrypid genus Leptotrypella lacking mural lacunae. All the New York 

species of Stereotoechus, Dyoidophragma, Leioclema, 

and Trachytoechus have the hyaline "central band" 

typical of the amalgamate wall, surrounded by a laminated zone that appears to line the zooecia. The relative thicknesses of the "central band" and the 

laminated zone are fairly constant for Stereotoeclius 

and Dyoidophragma but relative widths of these zones
MORPHOLOGY AND TAXONOMY 27

have not been considered in the definition of families 

and generally do not appear constant enough for such 

application.

Because of these difficulties with the supergeneric 

classification, a detailed study of the skeletal morphology of the Hamilton Trepostomata was made. The 

writer resorted to the approach first used by Cumings 

and Galloway, and studied longitudinal sections as 

well as the tangential sections, both under high magnifications, better to understand zooecial wall structure in three dimensions.

As a general rule, the laminated material of all 

diaphragms continues without interruption into the 

zooecial walls (fig. 8). The laminae of the diaphragms 

normally increase in number as they join the walls 

so a single diaphragm is continuous with a considerably thicker wall deposit. In the wall, the laminae 

may run parallel to the longitudinal direction of the 

zooecium for a considerable distance to form a lining 

to the zooecial tube; or, the laminae may extend directly into the wall at an angle to the longitudinal 

direction of the zooecium. Regardless of the inclination of the laminae as they enter the wall, all, or a 

part of the laminated material can be traced to its 

termination at the zooecial boundary in well preserved 

specimens from the Hamilton group. A diaphragm 

plus the distally connected wall deposit are interpreted 

to form a unit of skeletal growth that was deposited 

at approximately the same time and is here termed a 

diaphragm-wall unit (fig. 8).

The exact boundaries of a diaphragm-wall unit are 

difficult to define in many species and in poorly preserved material. It is commonly evident, however, that 

short, disconnected lengths of a zooecial wall are not 

continuous with diaphragm laminae. These independent wall units (that is, not connected to diaphragms) may completely encircle the zooecium 

(shaded area in fig. 8); or they may pinch out between two converging diaphragm-Avail units (coarsely 

laminated area in fig. 8) so that no independent wall 

unit can be distinguished in a corresponding position 

in the opposite wall of the zooecium. In these independent wall units, structure and inclination of the 

laminae are exactly the same as in the diaphragm-wall 

units and are interpreted to be essentially similar in 

origin to the wall portions of the diaphragm-wall 

units. One type of wall unit followed another in apparently no particular order as the zooecium grew 

distally. Distally placed units are considered progressively younger. Thus, active addition of skeletal 

material occurred only in the outermost wall unit at 

any one time.

Position of zooecial boundary

ited zone 

idary wall of authors)

Y$^ Diaphragm wall unit

\'/%j( Independent wall unit (discontinuous)

^B Independent wall unit (continuous)

FIGURE 8. Diagrammatic tangential and longitudinal sections of a 

zooecium of a generalized trepostome bryozoan illustrating the laminated structure of the skeleton. Line T-T' in the longitudinal view 

Indicates the position of the trace of the plane of -the tangential 

section. The position of the zooecial boundary in the tangential view 

is indicated by a dashed line because the boundary Is not seen in 

this view of an amalgamate wall. The small circular laminated 

structure is an acanthopore. In the longitudinal view the outlined 

walls outside the inferred limits of the single zooecium are thought 

to be deposited by the two adjacent polypides.

The above interpretation of the structural relationships of the wall laminae indicates that no part of the 

zooecial wall can be considered to be of secondary origin in the Hamilton trepostomes. However, some 

specimens of Leptotrypella (pi. 6, fig. 7; pi. 8, figs. 

4, 5b, and 7) have zooecial linings that suggest secondary deposition. The laminae run parallel to the 

longitudinal direction of the zooecia for a considerable distance, commonly passing under two or three 

distally located diaphragms before finally bending 

outward to the zooecial boundary. The apparent distinctness of this zooecial lining is emphasized by the 

light color of the laminated deposit of the lining relative to the darker appearing deposit of the zone of 

curved laminae. However, Cumings and Galloway 

observed that the laminae become distinctly darker in 

appearance in thin section if they are curved. This 

curving of laminae might be the explanation of the 

darkening, as the laminae in the lining are straight 

and generally much lighter in shade than the distal
28 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

extension of the same laminae as they bend toward 

the zooecial boundary. The important structural feature, however, is the continuity of the laminae from 

the light-colored lining into the darker curved part 

of the wall. In the specimens referred to in plates 6 

and 8 above, only a small proportion of the laminae 

of the zooecial lining can be traced to the zooecial 

boundary. Continuity of laminae from diaphragm to 

zooecial boundary is more generally seen as shown in 

text figure 8, however, and is characteristic of all 

the Hamilton genera except Leptotrypella.

Study of the longitudinal views of zooecial walls 

such as that carried on by Cumings and Galloway 

(1915, p. 359) suggests that a polypide contributes the 

inner half (relative to the polypide) of the deposits 

in the double or compound wall surrounding the 

polypide. The extent of the deposits formed by one 

polypide is marked by the zooecial boundary (text 

fig. 8). Adjacent polypides surrounding a zooecium 

contribute the material for the other half of the compound wall. The wall building from both sides of a 

zooecial boundary by adjacent polypides results in onehalf of the compound wall being the mirror image of 

the other, when viewed in longitudinal or tangential 

thin sections. Laminae commonly can be seen to end 

abruptly in the zooecial boundary region and abut 

against the ends of laminae from adjacent zooecia 

(see Cumings and Galloway, 1915, pi. 14, 15) and 

(pi. 14, fig. Id and pi. 17, fig. 6a) throughout the 

Trepostomata. Zooecial boundaries in general, however display a wide range of appearances that can 

be constant for a genus or that can vary considerably 

within a species or specimen. Some species and genera 

show little or no evidence, of discontinuity at the 

boundaries as seen in longitudinal sections (pi. 10, 

fig. la). The laminae from adjacent zooecia in such 

specimens appear to merge without interruption at 

the position of the boundary. Little notice has been 

taken of the longitudinal aspect of zooecial boundaries 

in previous descriptions. Future observations may 

prove that this feature is a useful taxonomic character in some groups.

The laminated zones seen lining the zooecia in 

tangential sections and interpreted as being secondary 

by Nicholson, Ulrich and Bassler, and Cumings and 

Galloway must be correlated with primary structures 

if observations and interpretations based on the longitudinal views of Hamilton trepostomes are correct. 

The fundamental reason for the contrasting laminated 

appearance of the zooecial linings and the hyaline or 

dotted "central bands" of the amalgamate wall was 

first pointed out to the author by Helen Duncan. The 

material of the zoaria, at least in the ephebic zone, is

laminated throughout. If the plane of a thin section 

cuts the skeletal material at right angles to the plane 

of the laminae, the laminae will obviously be seen in 

transverse view, one lamina upon the other. If the 

plane of a thin section cuts the skeletal material parallel to the plane of the laminae, the plane of the thin 

section will lie within a very few laminae, the laminated structure will not be apparent, and a hyaline 

or granular appearance will result, depending on the 

texture of the laminated material. Considering the 

orientation of the plane of the tangential section while 

looking at a longitudinal thin section, it is readily 

seen that in the usual amalgamate walls (text figs. 

9-12) the curving laminae intersect the plane of the 

tangential section at varying angles. Near the margin 

of the wall adjacent to the zooecial chamber, the 

laminae are approximately at right angles to the 

tangential section. Therefore, these laminae are cut 

transversely and appear as laminated areas in the 

tangential section. As the laminae approach the 

zooecial boundaries, however, they gradually curve 

through an arc of 90 degrees. Finally the laminae 

are parallel to the plane of the tangential section, and 

that area of the tangential slide appears to be nonlaminated and hyaline. The hyaline area, which extends for varying distances on either side of the 

zooecial boundary, is the "central primary band" of 

previous authors. The "secondary, laminated, zooecial 

linings" of previous authors are merely those areas 

where the wall laminations are cut at high angles by 

the tangential section.

In most integrate zooecial walls, the laminae, as 

seen in longitudinal section (fig. 13) never curve 

enough to become parallel to the plane of the tangential section over an appreciable distance. Thus, 

a tangential section intersects nearly all the wall 

laminae at high angles resulting in the laminated nature of the wall material being displayed throughout 

the thickness of the wall. At the narrow zooecial 

boundary zone the laminae terminate or bend sharply 

and are parallel to the plane of the tangential section 

only at the line of junction of zooecia. The zooecial 

boundary thus appears in tangential section as a line 

or narrow light shaded hyaline zone differentiated 

from the typical laminated structure on either side of 

the boundary.

Laminated structure must inevitably appear in, 

tangential sections wherever the laminations are at a G

high angle or perpendicular to the planes of the sections. The laminated structure of the acanthopores as 

seen in tangential sections is attributable also to perpendicular orientation of the deposits to the section. 

The laminae surrounding the central tubes of the acan-
MORPHOLOGY AND TAXONOMY 29

thopores were deposited as a series of superimposed 

cones pointing distally and making spinelike projections on the surfaces of the zoaria. The laminae are 

approximately perpendicular to the plane of the 

tangential section within the cones. If the cones are

o

truncated by a tangential section the acanthopore 

appears as a concentrically laminated structure.

Mural spines are characteristic of many species of 

Leptotrypella. and of two species of Atactotoechus, 

in the Hamilton group. Spines of similar size and 

position in zooecia have been reported in other Paleozoic and post-Paleozoic species. The spines in Hamilton species are projections of the laminated material 

either of the zooecial Avails or of diaphragms. The 

spines are laminated throughout, the laminae paralleling the surfaces of the spines as the spines were 

secreted. Sections cutting spines longitudinally show 

a series of superimposed cones which extend their 

laminae into the wall laminae without interruption. 

Sections cutting the spines transversely show a concentrically laminated structure.

Many spines appear to have a nonlaminated core 

(pi. 11, fig. 5a) of clear calcite. The nonlaminated 

appearance is again due to the approximate parallelism 

of laminae and the plane of the thin section. Minor 

adjustments of the focus of a microscope at higher 

magnifications readily demonstrate the completely 

laminated structure of the spines.

The spines apparently developed as the wall laminae 

formed. The base of a spine lying distal to another 

spine in the same zooecium is connected to wall laminae 

that partly surround or imbed the older spine (pi. 8, 

fig. 4). Thus, a spine developed in the early ephebic 

zone can be partly buried by subsequent deposits. 

There is some evidence that each spine originated at 

an approximately constant distance from the advancing 

aperture in the genus Leptotrypella.

The function of spinose structures lining the skeleton and pointed toward the soft polypide is a matter 

for speculation. From the study of recent bryozoans, 

it can be assumed that the polypide need not fill the 

entire chamber of the zooecium, so such a projection 

would not necessarily have interfered with the soft 

parts. The spines might possibly have been attachment supports for muscles or ligaments, but such 

speculation is premature.

The spines are not considered comparable with those 

discussed by Elias (1956 reference to spines not made 

 in abstract but included in talk) as nonbryozoan symbionts or penetrants. The direct connection of the 

laminae of the spines with those of the zooecial walls 

or diaphragms is convincing evidence that the spines 

were produced by the bryozoans.

Some of the Hamilton species of Leptotrypella and 

Trachytoeclius display minute pores in tangential 

views that are here termed mural lacunae (pi. 5, fig. 

3a; pi. 11, fig. 3a). The nature of at least some of 

these pores is clarified by study of longitudinal sections. In many of the species involved, the zooecial 

boundary is a relatively wide serrated zone, the laminae 

from adjacent zooecia either overlapping or falling 

short of the actual center line (pi. 6, fig. 5, 8a). Overlaps from one side are matched by shortened laminae 

from the other. Failure of groups of laminae from 

opposite sides of the boundary to make contact with 

each other results in minute equidimensional voids. 

The voids or lacunae are the minute pores of tangential 

sections.

In the Hamilton material the mural lacunae are 

filled with clear calcite and their nature is evident. 

In the material from the Traverse of Michigan, however, the voids are generally filled with opaque minerals 

such as pyrite and there is no indication of the true 

nature of the structures. Thus, zooecial walls with 

opaque lacunae were described as having a coarsely 

granular appearance superimposed upon a laminated 

wall structure.

TENTATIVE GROUPINGS OF GENERA FROM HAMILTON 

AND TRAVERSE GROUPS

As indicated in the foregoing discussion of wall 

structure, Middle Devonian genera do not readily 

fit into the present classification of the Trepostomata. 

The suborders Amalgamate and Integrata are based 

on the appearance of the zooecial walls in tangential 

sections. In some species integrate and amalgamate 

appearances can and do occur in a single zoarium. In 

other forms, one aspect is constant for a species or a 

genus. Integrate or amalgamate appearance alone 

is not considered a usable criterion for differentiating 

suborders. The tangential views of Middle Devonian 

genera that have been assigned to the families Heterotrypidae and Stenoporidae do not show consistent differences in microstructure. Many characters are so 

similar in Hamilton genera that the assignment of 

genera to one family or the other is largely arbitrary. 

An attempt was made by the author to study thin 

sections of at least the type species of most Paleozoic 

genera of the Trepostomata in the hope of establishing 

a more generally usable family classification from a 

reasonably complete representation of the order. Primary types of most type species of the genera are 

available but the original sections are too thick to 

show wall structure in adequate detail. Until a 

thorough study can be made, the Devonian genera 

known from the Traverse group of Michigan and the 

Hamilton group of New York are here segregated into
30 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

tentative supergeneric categories that are not formally 

named.

Study of longitudinal and tangential sections together indicates that the Middle Devonian genera 

can be sorted into two groups that may prove to be 

of subordinal rank. In the larger groups the genera 

are characterized by laminae that bend in a sweeping 

curve as they approach the zooecial boundary and 

intersect the boundary at right angles (text figs. 9-12). 

The walls commonly appear amalgamate in tangential 

view, but there are many exceptions, especially in 

forms having a very narrow zone of curved laminae 

resulting in a narrowly amalgamate to integrate appearance (pi. 6, figs. 6, 8b; pi. 13, figs. 5b, 5c). The 

width of the zone may vary sporadically or may be 

a constant specific character as in Leptotrypella mesostena mesostena (p. 55).

The smaller of the two main groups of Middle 

Devonian trepostomes is characterized by wall laminae 

that remain fairly straight as they approach the 

zooecial boundary (fig. 13). As a result, the laminations are oriented at an angle to the zooecial boundary 

and intersect the boundary at less than 90 degrees. 

This smaller group of Devonian Trepostomata commonly appears to be integrate in tangential view, but 

many specimens range from integrate to at least 

narrowly amalgamate (pi. 20, fig. Ic). Amalgamate 

appearance in walls formed by the fairly straight 

laminations results when the laminae intersect the 

zooecial boundaries at comparatively high angles, so 

that the plane of the laminae nearly coincides with 

the plane of the tangential section. There seems to 

be a critical angle between the planes of the laminae 

and tangential sections beyond which an amalgamate 

appearance is produced.

Within the two main groupings described above," 

five types of wall structure are distinguished in the 

material studied: four of the types fall into the first 

grouping characterized by wall laminae that are 

strongly curved near the zooecial boundaries and the 

fifth type is characterized by wall laminae that remain relatively straight as they approach the zooecial 

boundaries. Taxonomic characters other than wall 

structure were not considered in the initial grouping 

of the genera however, there is some correlation between wall structure and other characters as will be 

noted in the discussion of the individual groups. Use 

of as many characters as possible is desirable but at 

this exploratory stage, in which relatively few of the 

described trepostome genera have been critically 

studied, overall evaluation of possible family characters is impossible. Each type of wall structure difFIGURE 9. Diagrammatic longitudinal and tangential sections of a 

.single zooecium of Stereotoechus Duncan. Line T-T' on the longitudinal view of the zooecium indicates the position of the trace of the 

plane of the tangential section. In the tangential view the small circular laminated structure is an acanthopore, and the subtriangular 

tube is a mesopore.

ferentiated is named for a genus typically displaying 

that structure.

STEREOTOECHID WALL STRUCTURE

Wall structure in this group is typified by the genus 

Stereotoechus Duncan. As seen in longitudinal section (fig. 9), the zooecial wall laminae are short, 

broadly curved throughout their length, and largely 

transverse to the length of the zooecia. The zooecial 

boundaries commonly are not discernible in either 

longitudinal or tangential sections. The laminae from 

adjacent zooecia apparently merge without break or 

abut irregularly throughout the width of the wall 

without forming a well-defined boundary. In tangential view, the walls are amalgamate; the nonlaminated areas are characteristically broad, and the 

laminated areas lining the zooecia are correspondingly 

narrow. Diaphragms are uniformly thin in the genera 

included in this group and are difficult to trace into 

the zooecial walls.

In addition to Stereotoechus, the group includes 

Dyoidophragma Duncan, Eostenpora Duncan, and 

Calacanthopora Duncan.

LEIOCLEMID WALL STRUCTURE

The genus Leioclema Ulrich demonstrates another 

wall structure. As seen in longitudinal section (fig. 

10), the mesopore wall laminae are separated into well 

defined diaphragm-wall units that ordinarily can be 

traced across 2 or 3 adjacent mesopores. Independent 

wall units occur sporadically between the diaphragmwall units. Unlike the stereotoechid wall structure, 

the individual laminae trend approximately parallel 

to the longitudinal directions of the zooecia and
MORPHOLOGY AND TAXONOMY 31

FIOUHK 10. Diagrammatic longitudinal and tangential sections of 

Leioclema Ulrich. Line T-T' on the longitudinal view indicates the 

position of the trace of the plane of the tangential section. The 

tube containing the thick diaphragms is a mesopore. The tube on 

the right side of the longitudinal view containing a thin diaphragm 

is a zooecium. In the tangential view the small circular laminated 

structures are acanthopores, the central tube is a zooecium and the 

remaining tubes are mesopores surrounding the zooecium.

mesopores for a short distance before curving into 

the zooecial boundaries. Zooecial boundaries are intermittent or not discernible in species of Leioclema 

in longitudinal sections. If present, the boundaries 

are broad serrated zones of irregularly abutting 

laminae. The tangential view is always amalgamate 

but the hyaline areas are generally not as wide relative to the laminated zones as those of the stereotoechid 

group. The Devonian species of Leioclema show a

general irregularity and imperfect parallelism of the 

individual laminae (pi. 4, fig. 8) making up the independent and wall-diaphragm units. Diaphragms are 

thin and widely spaced or absent in the zooecia.

TRACHYTOECHID WALL STRUCTURE

A third type of wall structure is best developed in 

Trachytoechus Duncan. As seen in longitudinal section of fig. 11, the zooecial wall laminae trend almost parallel to the longitudinal direction of the 

zooecia for appreciable distances, then curve distally 

out toward the zooecial boundary and intersect the 

boundaries at right angles. The boundaries are generally poorly defined in longitudinal sections. In 

tangential view, the walls are amalgamate and commonly exhibit mural lacunae. The major differences 

between trachytoechid and leioclemid wall structures 

are the mural lacunae and the greater lengths of those 

parts of the laminae that approximately parallel the 

zooecia in the trachytoechid walls.

Eridotrypella Duncan and Eridocampylus Duncan 

seem to have approximately the same type of wall 

structure as Trachytoechus. All three genera have 

strongly lacunose walls that look very granular in the 

Traverse species. Also, the thin walls of the neanic 

zone are noticeably crenulated in species belonging 

to these genera. However, lacunose and crenulated 

walls are not unique with these three genera. Both 

Trachytoechus and Eridocampylus typically possess 

heterophragms and some species now placed in Eridotrypella have heterophragms in small numbers.

FIGURE 11. Diagrammatic longitudinal and tangential sections of a 

single zooecium of Trachytoechus Duncan. Line T T' in the longitudinal view indicates the position of the trace of the plane of the 

tangential section. The hooklike projection of the zooecial wall in 

the longitudinal view is a heterophragm. In the tangential view, 

the walls are amalgamate and show the small pores in nonlaminated 

areas. The small semicircles attached to the zooecial walls are 

heterophragms as they appear in the tangential view. The heterophragm indicated by hachures is suggestive of their appearance when 

flmbriate. The subtriangular area of laminated structure is the 

typical acanthopore in the species Trachytoechus hyalinus Boardman, 

n. sp.
32 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

LEPTOTRYPELLID WALL STRUCTURE

The genus Leptotrypella Vinassa de Regny demonstrates a fourth type of wall structure. As seen in 

longitudinal section (fig. 12), the laminae of the 

diaphragms enter the zooecial walls and continue 

distally as a zooecial lining. The laminae of the 

lining run parallel to the longitudinal direction of the 

zooecia for relatively long distances and generally 

pass under 1 or 2 distally located diaphragms. At 

any point along the length of a zooecium in the ephebic 

zone the cumulative deposits of 2 or 3 diaphragm-wall 

units form a fairly continuous zooecial lining. The 

individual laminae of the diaphragm-wall units finally 

either lose their identity or can be seen to curve 

distally out to the zooecial boundaries. In a few species 

such as Leptotrypella furcata (pi. 11, fig. 5a) diaphragm-wall units do not form a distinct zooecial lining even though the laminae do parallel the zooecia for 

a considerable distance. In some other species of 

Leptotrypella apparent zooecial linings are thin or 

discontinuous. The zooecial boundaries are typically 

marked by a ragged serrated zone of irregularly abutT'

FIGURE 12. Diagrammatic longitudinal and tangential sections of a 

single zooecium of Leptotrypella, Vinassa de Regny. Line T-T' in the 

longitudinal view indicates the position of the trace of the plane of 

the tangential section. In the longitudinal section, the laminae 

parallel the widely spaced lines that indicate the boundaries of 

diaphragm-wall and independent wall units. The hachured irregular 

line indicates the position of the serrated zooecial boundary zone. 

The more proximal of the two mural spines projecting from the upper 

wall was formed earlier than the distal spine and is partially buried 

by subsequent wall deposits. The tangential view is amalgamate 

with scattered mural lacunae in the vitreous area. The two large 

circular laminated structures inflecting the zooecial walls are 

acanthopores.

ting laminae from adjacent zooecia (pi. 10, fig. 3; 

pi. 14, fig. Id). The tangential view is typically 

amalgamate, but several species appear to^e integrate 

or show a combination of amalgamate and integrate 

features (pi. 6, figs. 6, 8b). Mural lacunae are common in several species of Leptotrypella.

In addition to Leptotrypella, Polycylindricus 

Boardman, n. gen. is tentatively included in this group.

ATACTOTOECHID WALL STRUCTURE

Typical wall structure is illustrated by the genus 

Atactotoechus Duncan. As seen in longitudinal section (fig. 13), the zooecial laminae remain relatively 

straight as they approach the zooecial boundaries and 

intersect the boundaries at low angles. Zooecial walls 

are formed by various combinations of diaphragm-wall 

units and independent wall units. Laminae entering 

the walls from the diaphragms either are inclined 

distally toward the zooecial boundaries and are relatively short, or parallel the zooecia for appreciable 

distances and then trend gradually to the boundaries. 

The laminae remain relatively straight as seen in the 

two dimensions of the longitudinal thin section and

FIGURE 13. Diagrammatic longitudinal and tangential sections of a 

single zooecium of Atactotoechus Duncan. T-T' in the longitudinal 

section indicates the position of the trace of the plane of the tangential section. The curved diaphragm forming a large subtriangular 

chamber in combination with the straight diaphragm is termed a 

cystoidal diaphragm. The most proximal diaphragm is a compound 

diaphragm formed by two simple diaphragms uniting over the greater 

part of their area.
MORPHOLOGY AND TAXONOMY 33

intersect the zooecial boundaries at varying angles 

of less than 90 degrees. The zooecial boundaries are 

defined by a-relatively straight line formed by the 

junctions of laminae from adjacent zooecia. The 

laminae may be abutting at the boundary or apparently continuous without break across the boundary. 

In the Hamilton specimens, boundaries either are 

darker or comparable to the shade of the surrounding 

wall deposits. In tangential sections the walls are 

generally integrate, but can appear narrowly amalgamate, depending on the angle that wall laminae make 

with the zooecial boundary.

In addition to Atactotoechus, Loxophragma Boardman, n. gen. is placed in this group. In both genera, 

acanthopores are relatively few and small; diaphragms 

are closely spaced; and curved, cystoidal, and compound diaphragms and cystiphra,gms occur in varying 

numbers.

ZOARIAL GROWTH AND TAXONOMY

The common occurrence of associated fragments of 

single ramose zoaria in the Hamilton group of New 

York State offers an unusual opportunity for the 

investigation of possible morphologic variation within 

zoaria and their method of growth. The existing 

literature provides little more than generalized observations and subjective interpretations regarding the 

amount of variation in complete zoaria of fossil 

Bryozoa. As a result, morphologic characters that are 

largely controlled by the stage of development within 

a zoarium have not been uniformly or adequately considered in the taxonomic study of the Trepostomata. 

In differentiating and describing species, astogenetic 

characters either have been ignored or considered 

to be relatively constant, and in some instances many 

names have been proposed for a single species. The 

ramose and fenestrate forms that are commonly found 

only as disassociated fragments are most likely to be 

misinterpreted. Cumings (1904, p. 50) mentioned the 

importance of this factor:

It must be borne in mind that a colony or stock composed 

of a number of individuals may be properly characterized as 

nepionic, while some of the individuals composing it are in 

reality mature, senile, or even dead.

And:

Enough has been determined, however, to make it certain that 

the founding of species upon slight variations occurring on 

small fragments of zoaria is an exceedingly questionable 

practice. The modifications of zoaria due to age may be profound. The writer has, for example, seen hundreds of specimens of most exceptionally well-preserved lower Helderberg 

and Hamilton Bryozoa, in very many cases showing the entire 

zoariurn. These specimens make it perfectly certain that 

many of the species that have been enumerated from these

formations, and founded on fragments of zoaria, are spurious. 

They may often enough represent merely different growth 

stages of a single individual. The only reliable criterion of 

a species is the entire zoarium (Cumings, 1904, p. 66).

The same caution has been expressed by L. W. 

Stach in work on Cenozoic and Recent Bryozoa. He 

ascribes morphologic variation within a zoarium and 

species to two factors: "(a) The difference in age of 

the zooecia in a zoarium which is generally expressed 

by the degree of calcification; and (b) the interplay 

between the tendency to a uniform development of all 

the zooecia and the environmental conditions in the 

neighbourhood of certain zooecia" (1935, p. 646).

DISTRIBUTION OF MORPHOLOGIC CHARACTERS 

WITHIN HAMILTON ZOARIA

Zoaria of Leioclema confertiporum (pi. 3, fig. 2b), 

Leptotrypella multitecta (pi. 7, fig. la), L. asterica 

(pi. 9, fig. la), and L. tuberata (pi. 14, fig. 2b) were 

assembled in nearly complete form. Most of the other 

ramose species are represented by at least one relatively 

large part of a zoarium. In rocks of the Hamilton 

group, the fragmented zoaria occur in isolated lensshaped masses or more rarely imbedded in the matrix 

in approximately their original configurations. All 

attempts to assemble the zoaria were at least partially 

successful indicating that each isolated concentration 

can be assumed to contain many fragments from at 

least one zoarium. After the zoaria were assembled, 

a continuous series of longitudinal thin sections was 

made from one of the main branches in each of a 

number of zoaria selected for study and the internal 

features were recorded in detail. Figs. 14, 15, and 21 

are based on three zoaria that were sectioned continuously from the most proximal fragments to the 

growing tips. Other assembled zoaria were sectioned 

at their extremities and at several intervening regions 

to determine the nature and limits of their variation. 

Zoaria that could not be assembled because of the 

difficulty of freeing the broken pieces from hard unweathered shale or because of too many missing pieces, 

were studied by sectioning a number of fragments 

chosen at random. In addition, sections were made 

of growing tips, fragments having the largest transverse diameters, branching stems, and fragments of 

any unusual appearance.

In the ramose Hamilton trepostomes the diameter of 

the inner thin-walled neanic zone of a zoarium does 

not become progressively smaller from bottom to top 

(figs. 14 and 15) but appears to vary erratically without regard to position in the zoarium. An increase in 

the diameter of the neanic zone generally occurs just 

proximal to the dichotomous branching of a stem 

(pi. 9, fig. If). This expansion is due to a multiplica-
34 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

Width of ephebic zone 

T""T '""

u 100 200 300 

LENGTH ALONG ZOARIUM, IN MILLIMETERS

FIGURE 14. .Graph of holotype of Leptotrypella (Leptotrypella) asterica 

Boardman, n. sp. (pi. 9). Vertical lines indicate numbers of diaphragms according to scale in right margin of figure.

tion in the number of zooecia as a result of an increase 

in the rate of gemmation of zooecia in the neanic 

region.

The total diameters of the branches are controlled 

largely by the width of the neanic regions, which 

constitute well over half of the total branch diameters 

in most species. As a result, branch diameters ordinarily show no progressive decreases distally, (figs. 

14, 15) similar to the neanic diameters. Branch diameters are locally affected by patchy areas of overgrowth that cause bulbous swellings and other irregularities in extreme developments.

In a large well developed ramose zoarium (fig. 14) 

the width of the outer thick-walled ephebic zone is 

relatively constant from the base upward for a considerable distance. Distal to this stable part of the

20 30 40 50 60 

LENGTH ALONG ZOARIUM, IN MILLIMETERS

FIGURE 15. Graph of zoarium 3524-17 of Leptotrypella (Leptotrypella) 

multitecta Boardman, n. sp. Vertical lines indicate number of diaphragms according to scale in right margin of figure.

zoarium, the ephebic zone progressively diminishes in 

width, becoming narrowest at the growing tips. Of 

the 188 growing tips sectioned, 82 percent show a 

thick-walled ephebic zone of some extent at the distal 

tips of the zoaria. The remaining 18 percent of the 

growing tips display zooecia possessing thin walls 

throughout. Figure 15 is based on a partly reconstructed zoarium representing either the distal part 

of a much larger zoarium or a nearly complete young 

zoarium since the width of the ephebic zone decreases 

progressively along the length of the available branch.

The number of diaphragms in the ephebic zones of 

the zooecia is approximately proportional to the corresponding widths of the zones (figs. 14, 16), so that 

diaphragms become progressively fewer distally as 

the ephebic zones decrease in width (pi. 7, fig. 1; pi. 

9). Presumably, diaphragm counts and width of 

ephebic zones can be proportional to growth stages of 

zooecia considering the manner of skeletal growth (p. 

27). The number of diaphragms in zooecia within 

a single zoarium of Atactotoechus fruticosus (p. 76) 

ranges from 27 in proximal regions to 1 or 2 in growing tips.

Zooecial diaphragms are too few and irregularly 

spaced to be used as indicators of growth stages in 

genera such as Dyoidophragma Duncan and Leioclema 

Ulrich. In this study the hemiphragms of Dyoidophragma and the diaphragms in the mesopores of 

Leioclema are relied upon as convenient growth stage 

indicators, because these structures are uniformly 

spaced in the ephebic zones and appear to have the 

same structural relationships and age significance as 

zooecial diaphragms in other genera.

The axial ratio is the ratio between the diameter 

of the neanic zone and the total diameter of the branch 

(fig. 19). As has been noted, the neanic zone shows 

no progressive changes in diameter in a zoarium so 

can be considered essentially constant for a large 

zoarium when considering ontogenetically controlled 

morphologic variation. The ephebic zone, however, 

becomes narrower distally so that branches consist of 

a progressively larger proportion of neanic zone and 

a correspondingly smaller proportion of ephebic zone. 

Thus, the value of the axial ratio becomes greater distally as the growth stages of the zooecia in a zoarium 

become younger (fig. 17). The axial ratio then is 

another indicator of ontogenic development but is 

affected by local irregularities in neanic zone diameters 

and generally is not as reliable for growth interpretations as the width of the ephebic zone or the number of 

diaphragms in the zooecia. The axial ratio is especially misleading if it is based on measurements of 

regions just proximal to dichotomy because the neanic
MORPHOLOGY AND TAXONOMY 35

zones at these places are larger than normal, whereas 

the ephebic zones do not exhibit comparable changes. 

Consequently, the values of the axial ratios measured 

just proximal to dichotomy of a branch are too high 

to give an accurate idea of the stage of zoarial development that had actually been attained.

Zooecial wall thickness shows little correlation with 

growth stages defined by the width of ephebic zones 

and numbers of diaphragms. In general, walls attained their maximum thickness at the point where 

the third or fourth diaphragm occurs in the early 

ephebic zone so there is no general increase in wall 

thickness as diaphragms were added subsequent to 

this early growth stage.

The zooecial surface angle is reasonably constant 

in most ramose species and varies little from 90° in 

most genera studied. However, in Atactotoechus cartus the angle is unusually small and shows a poor 

correlation with growth stages (fig. 18) becoming 

generally larger in older parts of the zoarium.

Mural spines and small spherical cysts occurring in 

Leptoirypella are ordinarily distributed irregularly 

through a zoarium. In zoaria displaying few mural 

spines, several may be seen in one thin-section and 

none in another from the same zoarium. Zoaria containing abundant mural spines have a concentration 

of them near the zooecial bends. A concentration of 

spines commonly occurs at the proximal ends of zooecia 

in incrusting overgrowths (pi. 8, fig. Y). Cysts appear 

to be abundant in some parts of a zoarium and rare 

in other parts (pi. 9, fig. 1). Where abundant, they 

are distributed throughout the length of the zooecia 

in the ephebic zone without any noticeable concentration.

Characters seen in the tangential views are normally 

more constant throughout a zoarium than those characters displayed in longitudinal views. The only important exceptions to this general observation are the 

variability of the zooecia in the monticules and the 

irregular occurrence of amalgamate and integrate 

zooecial walls in some species.

Monticules are fairly evenly spaced throughout a 

zoarium. However, the nature of the included elements may be extremely variable. One monticule may 

contain many mesopores and adjacent monticules in 

the same zoarium few or none; or some monticules may 

display thick-Availed zooecia and enlarged acanthopores 

and others in the same zoarium may contain zooecia of 

normal wall thickness and acanthopores of normal 

size.

The diameters of zooecia vary within the small area 

covered by a tangential thin section, and the variation 

throughout the zoarium is approximately equal to that

determined from the single section. Configuration of 

the zooecia as seen transversely is somewhat variable 

but does not progressively change from one part of 

the zoarium to another.

The distribution of mesopores and acanthopores in 

the intermonticular areas is relatively constant throughout a zoarium. Ontogeny has no effect on their occurrence, for both mesopores and acanthopores have their 

origins at the beginning of the ephebic zone in the 

Hamilton species. Once these structures appear, they 

do not multiply noticeably as ephebic growth continues.

ZOARIAL. VARIATION AND SPECIES CRITERIA

Fortunately, it is not necessary to have complete 

zoaria to do realistic taxonomic work, once the growth 

characteristics, based on related zoaria, have been 

reasonably well established. With regard to taxonomy, 

a colony can be thought of as merely a convenient 

physical linking of individuals of similar genetic 

makeup. These individuals may or may not display 

a number of progressively changing growth stages 

superimposed on morphologic variations due to either 

physiological or microecological differences. Since the 

average sized fragment represents a restricted growth 

stage, a reasonable number of disassociated fragments 

of a species provide an adequate approximation of the 

range and morphologic characteristics of the growth 

stages and at least those morphologic variations that 

are fairly evenly distributed within the colonies.

The characters discussed in the preceding section 

on morphologic variation within zoaria are those most 

often used in differentiating species. These species 

characters fall into two natural groups: those that are 

independent of ontogeny, and those controlled largely 

by ontogeny or growth stages. Species characters that 

are independent of ontogeny form two subcategories: 

(a} characters that display relatively large variations 

distributed erratically in a zoarium, and (&) characters that remain relatively constant throughout a 

zoarium.

The use in taxonomy of the characters subject to 

erratic variation will always be seriously hampered by 

the general lack of complete zoaria. The nature and 

limits of variation of the erratic characters for the 

zoarium cannot be determined from a small fragment. 

Thus, the erratic characters are generally poorly understood, and therefore less useful in taxonomy. Good 

examples of such characters are the mural spines and 

cysts of Leptotrypella and the nature of the monticular zooecia in many of the Hamilton species.

Characters of the second category that show little 

variability throughout the zoarium are much more
36 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

useful as criteria for species. In general, a fairly good 

idea of the nature and amount of variation within a 

zoarium can be obtained from one or two fragments 

of that zoarium. In the Hamilton material, characters that have been found to be fairly constant within 

a zoarium include zooecial wall thickness, shapes of 

the zooecia in transverse view, numbers of acanthopores and mesopores per zooecium, nature of the walls 

(crenulate or non crenulate) in the neanic zones, 

nature of the zooecial linings and boundaries, occurrence of cystiphragms and compound diaphragms, and 

zooecial surface angles. However, any one of these 

characters can vary erratically in certain species and 

genera and should be used with a certain amount of 

caution.

The relatively constant characters commonly vary 

in some degree, depending on the species, from one 

zoarium to another. Fragments from a reasonable 

number of zoaria must be examined before a species 

concept can be defined with assurance. Large numbers of sections, about 330 sections from 46 zoaria, of 

Leptotrypella asterica, (p. 58) were studied in an 

attempt to describe this extremely variable species. 

As indicated in the species description, wide ranges of 

variation were found in certain characters that are 

generally fairly constant. The variations of several 

of these characters are apparently related and can be 

correlated. It can be demonstrated in a few zoaria 

that intrazoarial variations of such characters as wall 

thickness and spacing of diaphragms are approximately proportional and are wide ranging.

Most zoaria of L. asterica show these same characters to be relatively constant within a zoarium. 

However, interzoarial variation in this larger group is 

comparable to that variation found in a single zoarium 

in the few inconstant zoaria of the species. The only 

safeguard for interpreting such a variable species is 

a large number of specimens. Also, the presence of 

the complete range of variability in a single zoarium 

constitutes a happy verification for the inclusion of 

widely variable zoaria in one species.

Zoarial growth habit has been considered to be an 

infallible species character in Paleozoic forms. Growth 

habit is a reliable species criterion for many and probably most species, but there are exceptions (p. 8). 

Several Hamilton species that ordinarily display conspecific overgrowths on ramose zoaria also produce 

incrusting zoaria or a combination of incrusting and 

ramose zoaria on nonbryozoan. surfaces. Thin-sections 

illustrating combined growth habits in a single zoarium or different growth habits within single species 

are shown on pi. 3; pi. Y, fig. 3; pi. 11, fig. 6; pi. 1Y, 

fig 4; and pi. 22, fig. 1.

The group of species characters controlled by ontogeny is relatively small but should prove exceedingly 

useful in taxonomy. Characters of this type are best 

adapted to statistical studies based on scatter diagrams, for such diagrams can be designed to demonstrate growth stages. The width of the ephebic zone, 

number of diaphragms, axial ratio, and in a few species the zooecial surface angle are characters that lend 

themselves to such analysis. The ontogenetic characters were found to vary so widely within one zoarium 

that as many as three "species" could be distinguished 

from one end to the other. Thus, a wider more realistic range of species variation must be allowed in structures that are controlled by growth stages.

The ontogenetic characters can be treated successfully in the ordinary collection composed of small 

disassociated fragments of zoaria if a reasonable 

amount of material is available for a species. First, 

it is necessary to establish a means of defining growth 

stages. The number of zooecial diaphragms at a particular level in the zoarium is considered the independent variable in most of the Hamilton genera. It 

is generally assumed that the diaphragms served as 

floors upon which the soft polypides rested. Each 

additional diaphragm then, represented an advance 

in the distal growth of the individual and the passage 

of an unknown amount of time (p. 2Y).

It is not necessary to know the absolute range of 

the number of diaphragms possible in a species being 

described. Due to the nature of growth in ramose 

zoaria, the minimum number of one to a few diaphragms is assumed possible in the ramose Hamilton 

species. The maximum number of diaphragms will 

ordinarily not be known. However, a growth stage of 

a restricted number of diaphragms can be defined and 

further characterized with reference to the corresponding values of the other ontogenetic characters. Several arbitrarily restricted growth stages, will have a 

set of corresponding values for the dependent variables that will characterize individual species. The 

wider the range covered by a series of growth stages 

and the more specimens measured for each growth 

stage, the more accurate is the characterization. These 

figures can then be presented in the form of scatter 

diagrams and resulting statistical tests, or they may 

be presented in tabular form as is done in the taxonomic section of this paper.

Figures 16 to 19 are based on three zoaria (in fig. 

18, four zoaria are included) of Atactotoeclius cartus 

cartus (p. Y3). The three zoaria are part of a collection of 13 that were obtained from the Portland 

Point member in USGS collection 3551. The zoaria 

occurred as isolated, lens-shaped masses of broken
10

MORPHOLOGY AND TAXONOMY

12

37

0.5 1.0 1.5 

WIDTH OF EPHEBIC ZONE, IN MILLIMETERS

1.9

FIGURE 10. .Peripheral scatter diagram of three zoarla of Atactotoechua 

oartua cartua from collection 3551. The area defined by the plotted 

points of each zoarlum Is enclosed by a line. Each style of line Identifies the same zoarlum In figures 16 to 19. The crosses Indicate the 

median points of the respective zoaria.

fragments in a 3-foot stratigraphic zone along 360 

feet of the stream channel of Menteth Creek on Canandaigua Lake. Because the mudstone matrix was relatively hard and unweathered, it was impractical to 

clean each of the many fragments and attempt to 

assemble the zoaria. The writer assumed that each 

isolated mound of material was a separate zoarium

12

10

0.90-91 0.80-81

AXIAI °ATIA_ NEANIC ZONE DIAMETER AXIAL RATIO- TOTAL D |AMETER 

0.70-71

FKIURB 17. Peripheral scatter diagram of three zoarla of Atactotoechua 

oartua cartua from collection 3551. The area defined by the plotted 

points of each zoarium is enclosed by a line. Each style of line 

identifies the same zoarium in figures 16 to 19. The crosses indicate 

the median points of the respective zoaria.

10

20° 30° 40° 50° 60° 70° 

ZOOECIAL SURFACE ANGLE

80° 90°

FIGURE 18. Peripheral scatter diagram of the three zoaria of 

Atactotoechua cartua cartua that are represented in figures 16 to 19 

plus a fourth zoarium from the same collection, 3551. The area 

defined by the plotted points of each zoarium is enclosed by a line. 

The crosses indicate the median points of the respective zoaria.

(p. 74). ,As many as 30 longitudinal'sections were 

made from fragments picked at random from each 

lot. The 3 zoaria chosen for the graphs illustrate the 

ontogenetic and astogenetic range of variability observed in the 13 zoaria*

6.0

15.0

55 4.0

3.0

3.0 4.0 5.0 6.0 

DIAMETER OF ZOARIUM, IN MILLIMETERS

7.0

FIGURE 19. Peripheral scatter diagram of three zoarla of Atactotoechua 

cartua cartua from collection 3551. The area defined by the plotted 

points of each zoarium Is enclosed by, a line. Each style of lln« 

identifies the same zoarium in figures 16 to 19. The crosses indicate 

the median points of the respective zoaria.
TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

The differences between zoaria represented in figures 16 to 19 are all based on characters that are controlled by ontogeny. Apparently, each of these three 

zoaria had attained a different stage of astogenetic 

development at the time it was killed. The zoarium 

represented by the solid line is interpreted to have 

reached the most advanced stage of development because it shows the greatest numbers of diaphragms, 

the lowest axial ratios and widest ephebic zones. Also, 

the complete range of growth stages occurs in this 

zoarium as is indicated by the area covered by its 

scatter diagram extending to the smallest numbers 

of diaphragms, the narrowest ephebic zones, and high 

axial ratios. The zoarium represented by the dotted 

line was the youngest as indicated by the position of 

the area representing that zoarium at the lower left 

hand corners of the diagrams in figures 16-18. The 

colony represented by the dashed line reached an intermediate stage of zoarial development. The crosses 

indicating median points of the three zoaria are 

aligned from the lower left to the upper right in the 

order of least to greatest ontogenetic development and 

give some indication of the average growth stage of 

each zoarium.

Figures 16 and 17 dealing with the number of diaphragms, width of ephebic zones, and axial ratios 

show fairly good correlation as might be expected. 

Figure 18, in which the zooecial surface angle is 

plotted against the number of diaphragms, shows very 

poor correlation. In general, the zooecial surface angle 

is not a good indicator of growth stage.

Figure 19 is a plot of the diameters of the zoaria 

against the diameters of the neanic zones thus illustrating the axial ratio. The youngest zoarium has the 

highest axial ratios and therefore is confined to the 

area near the 0.9:1 line. The most mature zoarium 

represented by the solid line shows an axial ratio 

approaching the 0.9:1 line and crossing the 0.7:1 line 

in older parts of the zoarium. The extremely elongated areas indicate a good correlation between these 

two measurements. Good correlation is expected because the neanic zone constitutes such a large proportion of the total branch diameter, as is indicated by 

the high values of the ratios.

MODE OF RAMOSE ZOARIAL GROWTH

The present investigation of the unusually well preserved Hamilton specimens has resulted in an hypothesis concerning the mode of growth of the ramose 

colonies.

Lee (1912, p. 143) after a study of Carboniferous 

trepostomes, concluded that the axial ratio (ratio of 

the diameter of the neanic zone to the diameter of the

branch) is constant within a zoarium and a species. 

His theory of constant axial ratios led him to propose 

a resorption theory of growth for ramose colonies. 

Apparently, Lee found that all of his specimens had 

well-developed ephebic zones across their growing tips. 

According to Lee, as the branch increased its length 

distally, growing zooecia located in the center of the 

branch curved outward from the branch axis, keeping 

their ephebic zones constant in width by resorbing the 

proximal ends of the ephebic zones and depositing 

at an equal rate at the distal ends. This compensating 

process brought the zooecia to their final positions in 

the cortical or ephebic zone of the zoarium. At this 

stage the ephebic zones were apparently considered to 

be fully developed and outward growth of zooecia 

ceased, for Lee states (1912, p. 144) that branches 

possess their full diameter from the beginning, and 

further comments:

* * * in each species the dimensions of the axial and peripheral 

regions not only are invariably the same in branches of the 

same diameter, but also that in the smallest as well as in the 

largest these two regions have invariably the same relative 

proportions (1912, p. 143).

Study of the ramose forms of the Hamilton specimens indicates that resorption of skeletal material was 

probably part of the growth processes of the colonies. 

Otherwise, there is little agreement between Lee's hypothesis and that presently favored for the Devonian 

material.

Study of sectioned growing tips and relatively long 

branches that were sectioned in their entirety provides 

three main observations that must be considered in a 

growth hypothesis. First: narrow arched zones paralleling the rounded ends of the branches extend across 

the neanic regions at irregular intervals proximal to 

the tips. The zooecia at these zones contain one or 

more diaphragms and the walls are thickened to some 

extent (pi. 7, fig. 2; pi. 9, figs, le, If; pi. 10, figs. 2, 5; 

pi. 19, fig. 4). The thick-walled zones within the 

neanic regions have the same general appearance as 

the proximal parts of ephebic zones (pi. 10, figs. 2, 5). 

Second: about 80 percent of the growing tips show 

thick-walled ephebic zones that are as long or longer 

than the thick-walled zones of the neanic regions 

proximal to the tips (pi. 7, fig. 2; pi. 9, fig. le; pi. 10, 

fig. 5; pi. 22, fig. 2). Third: ephebic zone width, number of diaphragms and axial ratio all indicate that 

there is a gradual decrease in astogenetic development 

through a considerable length of the distal end of each 

zorium.

These observations are interpreted to indicate that 

growth was cyclic and that the thick-walled zones 

arching across the neanic regions represent abandoned
MORPHOLOGY AND TAXONOMY 39

growing tips that underwent varying amounts of resorption. A suggested cycle of growth in a ramose 

colony is as follows: new zooecia were introduced by 

lateral gemmation in the neanic zone; the new zooecia 

along with those persisting in the neanic zone from 

earlier cycles grew distally, the cumulative effect extending the length of the branch. A thick-walled 

ephebic zone was then formed around the tip (fig. 

20). Next, the polypides resorbed the skeletons from 

the apertures back toward the bases of the thickwalled region, removing distal lengths of the thick 

walls and associated structures such as diaphragms. 

The amount of resorption varied greatly among species 

and within one colony from cycle to cycle and was 

probably controlled in part by recurring environmental conditions. Another cycle began with the 

reneAved growth and gemmation of thin walled tubes 

of the neanic zone. The new thin-walled growth was 

directly connected to the thick-walled remnants of the 

previous cycle thereby forming continuous tubes.

As the colony grew distally, zooecia at the growing 

tip were gradually forced away from the center of 

the branch, their places in the center taken by new 

zooecia formed by gemmation. The older zooecia

Growing tip region

Remnant of thick-walled ephebic 

region of previous growing tip

Diaphragm

Thick-walled ephebic region 

Thin-walled neanic region

FiotMH 20. Idealized diagram of a ramose bryozoan In longitudinal 

view Illustrating the essential structures involved in the growth of 

a ramose colony.

eventually attained permanent positions opening along 

the sides of the branch. Here, there are no signs of 

resorption such as is exhibited in the neanic zone and 

the growing tip. The present interpretation of complete diaphragms as "floors" that supported the polypides indicates that the living chamber was distal to 

the last formed diaphragm. It might be assumed that 

skeletal changes could have occurred only in regions 

adjacent to the polypide, thus any changes of the 

skeleton would have to proceed from the distal living 

chamber in a proximal direction. Further, the configuration of zooecial wall laminae indicates that 

zooecial growth was limited to the outer surfaces of 

the living chamber (p. 27). Width of the ephebic 

zone, number of diaphragms, and other intrazooecial 

structures increase progressively toward the base of 

a colony indicating that the distal growth of the zooids 

in the thick-walled ephebic zones continued roughly 

proportional to time. The observed progressive change 

in axial ratio then was controlled by a gradual addition of deposits in the ephebic zone and no accompanying change in the neanic zone, zoarial features 

that are consistent with this hypothesis of growth.

The relatively constant width of ephebic zones and 

numbers of included diaphragms in the most proximal 

part of large zoaria, such as the holotype of Leptotrypella asterica (fig. 14) indicate that zooids attained 

their maximum length and died, or at least ceased 

adding to their skeletons. The dead or dormant parts 

of zoaria served to support the growing parts and to 

keep them upright and above the accumulating bottom 

deposits. Whether the proximally located zooids were 

killed because accumulating deposits covered them or 

died before being covered because of physiologic limits 

to their growth is not known. Many Hamilton zoaria 

haAre overgrowths, not always conspecific, occurring 

in patches or completely covering their proximal regions. Zooids in the overgrown tubes were either 

already dead or were killed as the overgrowths covered them. Thus a large zoarium may be pictured as 

progressively dying from the base upward, growing 

normally in distal regions and covered here and there 

by patches or sheets of living overgrowth.

An overgrowth is almost completely separated from 

the incrusted or primary colony by a basal lamina. 

Leptotrypella multitecta ordinarily displays well developed overgrowths that seem to have originated from 

a few zooecia in the incrusted colony. PI. 7, fig. 4a 

shows a large section of the holotype that includes 

the probable origin of an overgrowth that is both 

incrusting and ramose. The zooecia at the end of the 

primary colony continue into the secondary colony or 

overgrowth without interruption, forming a source
40 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

for the secondary colony. The secondary colony grew 

distally in all directions from the restricted region of 

its origin. The normal curve or bend of a zooecium 

is always concave in the proximal direction of growth. 

The incrusting overgrowth in part extended downward, relative to the primary colony, but since that 

direction is distal relative to the secondary colony 

the orientation of the zooecia of the overgrowth is 

reversed relative to the primary colony, as is seen in 

the upper center and lower left part of the figure (pi. 

7, fig. 4a). Fig. 21 shows the decrease in width of 

the ephebic zone of the incrusting part of the secondary colony away from its origin and toward the 

base of the primary branch. In addition, overgrowth 

grew distally upward (upper right corner of fig. 4a 

of pi. 7) in the form of a branch, there being no support for incrusting growth in this direction.

In addition to the ordinary dichotomous branching 

of ramose colonies and the erratic branching resulting 

from overgrowths, the genus Polycylindricus commonly displays a "secondary" type of branching resulting in discordantly small branches projecting at 

right angles to the supporting stem (pi. 16, figs. 2, 4). 

These small side branches are formed by normal thinwalled tubes that arise from the thick-walled tubes of 

an ephebic zone without the intervening basal lamina 

that occurs in normal overgrowth. Local and relatively rapid growth of the thin-walled tubes apparently provided a neanic region for the secondary 

branch. Similar branching is known in Leptotrypella 

mesostena mesostena (p. 55) and Atactotoechus fruticosus (p. 76).

The nature of the basal attachments of ramose colonies has not been satisfactorily revealed by the 

Hamilton material. Zoaria showing combinations of 

incrusting and ramose habit as in pi. 7, fig. 3; pi. 11, 

fig. 6; and pi. 22, fig. 1, may represent either normal 

basal attachments or small colonies that were as much 

ramose as incrusting. The scarcity of zoaria showing 

both incrusting and ramose habit might indicate that

50 100 150 

LENGTH ALONG ZOARIUM, IN MILLIMETERS

FIGURE 21. Graph of holotype of Leptotrypella multitecta BoarcLman, 

n. sp. The dashed line indicates the width of the ephebic zone of 

the primary colony. The solid line indicates the width of the ephebic 

zone of the secondary colony, in part incrusting on the primary 

colony and in part extending beyond the primary colony as a branch.

such colonies were rare and the basal attachments of 

the great majority of ramose colonies were of a different nature.

SYSTEMATIC DESCRIPTIONS

Order TREPOSTOMATA Ulrich, 1882 

STEREOTOECHID GROUP

Genera from the Hamilton group that display 

zooecial wall structure similar to that of the genus 

Stereotoechus Duncan are placed together. The 

zooecial wall laminae of the included genera are typically short, broadly curved throughout their length, 

and largely transverse to the length of the zooecia 

(see p. 30 and fig. 9)'.

Genus STEREOTOECHUS Duncan

1939. Stereotoechus Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 260. 

1939. Anomalotoechus Duncan (part), ibid., p. 187.

Type species. /Stereotoechus typicus Duncan 1939.

Original definition. Zoarium laminar, superimposed 

layers may form small masses. Groups of larger 

zooecia present. Walls thick, completely amalgamate, 

laminated, irregularly thickened at frequent intervals, 

occasionally slightly beaded. Diaphragms complete 

and numerous. Mesopores absent. Acanthopores well 

defined, laminated, located at or near junctions of 

zooecial walls.

Remarks.^Mesopores, as defined in this paper, are 

very rare in some species and unknown in others. 

Diaphragms are uniformly thin in this genus.

Leptotrypal spinifera Duncan (1939, p. 222, pi. 5, 

figs. 3-5) is here reassigned to Stereotoechus. Anomalotoechus typicus Duncan (1939, p. 189, pi. 1, figs. 4-7) 

the type species of Anomalotoechus, is considered to 

be a synonym of S. spiniferus (Duncan) differing only 

in displaying a more advanced growth stage. Holotype specimens of both S. spiniferus and A. typicus 

possess a stereotoechid wall structure. Also, the diaphragms of A. typicus differ little in arrangement 

from Stereotoechus typicus, the type species of Stereotoechus, and all remaining characters of the holotypes 

of both Z.? spinifera and A. typicus are consistent 

with the definition of Stereotoechus. The remaining 

species assigned to Anomalotoechus by Duncan (1939, 

p. 188) that do not belong in Stereotoechus are: 

Anomalotoechus tuberatus Duncan, now assigned to 

Atactotoechus (p. 70) and Monticulipora ? marylandensis Ulrich and Bassler 1913, now placed in the 

synonymy of Leptotrypella amplectens (Grabau) 1899 

(p.60).

Cyphotrypa traversensis Duncan (1939, p. 200, pi. 

4, figs. 10-12) displays a stereotoechid wall structure
SYSTEMATIC DESCRIPTIONS 41

and the other characteristics of the genus and is here 

reassigned to Stereotoechus. Leptotrypa? nicholsoni 

Duncan (1939, p. 221, pi. 5, figs. 6-8) is considered a 

young growth stage of S. traversensis (Duncan) and is 

included in the synonymy of that species. Stigmatella, 

alpenensis Duncan (1939, p. 233, pi. 4, figs. 4-6), Monticulipora monticula White (1876, p. 27), Cyphotrypal 

shearsbyi Crockford (1941, p. 105, pi. 1, fig. A) and 

Orbiffnyella tenera, Bassler (1911b, p. 61, pi. 8, figs. 

1-3; pi. 11, fig. 3) are reassigned to Stereotoechus.

The following species are now assigned to Stereotoechus :

alpeiiensia (Duncan) 1939

irregular-is McNnir 1942, p. 349, pi. 49, figs. 1-4

monticulux (White) 1876

shearsbyi (Crockford) 1941

spimfer-ns (Duncan) 1939

A.nomaloto6ChuK typicns Dnncan 1939, included in

synonymy.

teneruft (Bassler) 1911 

traversensis (Duncan) 1939

Leplotrypaf nicholsoni Duncan 1939, included in

synonymy. 

typicns Duncan 1939

Stereotoechus cf. S. typicus Duncan 

Plate 1, figure 1

1939. Stereo tocchus typicus Duncan, Univ. Michigan, Mas. 

Paleontology, Contr., v. 5, p. 261, pi. 13, figs. 10-13.

Only two specimens were found in the Hamilton of 

New York. They agree with the qualitative characters 

of the Michigan holotype specimen. In addition to 

the characters described by Duncan (1939, p. 261) 

both the Michigan and New York specimens possess 

small intrazooecial cysts, ranging from spherical to 

rod shaped to irregularly globular. The cysts may 

be isolated or in clusters and are generally filled with 

brown granular material. Many of the cysts have 

definite walls of laminated skeletal material connected 

directly to the laminae of the diaphragms. A few 

cysts are alined in the planes of the diaphragms and 

the diaphragms are inflected around the cysts.

The quantitative measurements show some variation 

that might prove to be intraspecific if enough specimens were available for study.

Holotvpe,

19881 from Two specimens 

Traverse from New 

(iroup York

9-10 8-9 

. 78 . 40-. 50

Zooecia in 2 mm.____________________

Acanthopores per zooecium. __________

Maximum diameter of meguzooeciu

mm__ .30 .38 

Average zooecial wall thickness.-.do.__ .05 .05

Type: Figured specimen USNM 133853.

Occurrence: Centerfield limestone member of the Ludlowville shale, USNM collection 275A, Batavia quadrangle, New 

York.

Genus DYOIDOPHRAGMA Duncan

1939. Dyoidophragma Duncan, Univ. Michigan, Mus. Paleontology, Contr., vol. 5, p. 240.

Type species. Dyoidophragma typicale Duncan 

1939.

Emended definition. Zoaria are incrusting to irregularly massive and commonly develop one or more 

layers of overgrowth. Monticules occur, but height 

and included elements are extremely variable. The 

neanic region is generally short and recumbent. The 

ephebic zone is relatively long and zooecia open perpendicularly to the surface of the zoarium. Zooecial 

walls are fairly uniform in thickness. Thick laminated 

hemiphragms are characteristic of the genus and 

project from the zooecial walls on the proximal side 

of the zooecia. Diaphragms are thin, complete, and 

can occur in both zooecia and mesopores. Mesopores 

are rare to abundant in different species; acanthopores 

are laminated, large and numerous.

Remarks. Configurations of the laminae of the 

hemiphragms of Dyoidophragma afford evidence for 

the position of the lime secreting tissue of the polypides that formed the hemiphragms. Assuming parallelism of the skeletal laminae and the secreting tissue, 

little or no skeletal material was added from the proximal (generally lower) side of the shelf like hemiphragms (fig. 22). Rather, a hemiphragm apparently 

was built from its upper surface by the secreting tissue 

that gradually added laminae, extending each successive lamina progressively farther out into the zooecial cavity. The laminae were abruptly terminated 

after lapping over the end of the growing hemiphragm, forming an irregularly ridged undersurface 

to the hemiphragm. A few hemiphragms show a 

slight recurving of skeletal laminae on their proximal 

side, implying either a similar recurving of the secreting tissue around the ends of the hemiphragms or a 

very unequal addition of lime by secreting tissue 

located below the hemiphragms.

The positions of the diaphragms in the zooecia are 

irregular and seemingly independent of the hemiphragms. This apparent independence of the diaphragms, or lack of diaphragms altogether in many 

zooecia, leaves the position of the complete polypide 

unknown relative to the hemiphragms, as diaphragms 

are generally considered to be floors upon which the 

complete polypide rests.

The addition of laminae from only one side of a 

hemiphragm affords comparison of these structures 

with zooecial walls of the Trepostomata. The asymmetrical structure of the hemiphragm is similar to the 

structure of the half of a zooecial wall built by a 

single polypide. The ridged underside of the hemi-
42 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

FIGURE 22. Diagrammatic longitudinal section of a zooecium and mesopore of Dyoidophragma polymorphism illustrating the laminated

structure of the skeleton.

phragm would correspond to the outer zooecial 

boundary of the zooid. If laminae were added symmetrically from both sides of the hemiphragm, the 

laminated structure would appear identical with the 

typical zooecial wall that is added to equally on both 

sides of the zooecial boundary by adjacent polypides. 

The zooecial boundary of a wall commonly is marked 

by terminations of laminae abutting against each 

other from adjacent zooecia in a ragged or irregularly 

serrated zone between the zooecia. This raggedness is 

caused by the irregularly unequal lengths of neighboring laminae and has the same appearance in longitudinal section as the irregularly ridged underside of 

the hemiphragms.

Dyoidophragma polyinorphum Boardman, n. sp. 

Plate 2, figures 1-6

Diagnosis. Incrusting to irregularly massive species distinguished by abundant mesopores without 

hemiphragms; hemiphragms evenly spaced in zooecia; 

diaphragms irregularly spaced or absent in both 

zooecia and mesopores.

Description. Zoaria are mcrusting to irregularly 

massive. The incrusting specimens occur commonly 

on crinoid columnals and rarely on brachiopods, gastropods, or other bryozoans. Overgrowth is common; 

as many as 3 or 4 layers were developed in older 

colonies. Ordinarily, each layer of overgrowth displays a different growth stage. Monticules are vari-
SYSTEMATIC DESCRIPTIONS 43

able in height; a few display zooecia with thickened 

walls and enlarged acanthopores; other monticules 

contain megazooecia with walls and acanthopores unmodified.

The neanic region generally can not be defined in 

the usual thin and thick-walled sense. The earliest 

zooecial wall at its junction with the basal lamina 

possesses the thickness and laminated structure characteristic of ephebic walls. The directional trend of 

the zooecial tube proximal to the earliest hemiphragm, 

hoAvever, is nearly parallel to the basal lamina, as in 

the thin-walled neanic regions of most incrusted species of the Trepostomata. The neanic zone is arbitrarily defined to include the recumbent part of the 

zooecium proximal to the first hemiphragm (fig. 22). 

A very few zooecia display single thin diaphragms 

within or partly within the neanic zone. The zooecial 

bend is abrupt, generally coincides with the distal end 

of the neanic zone and changes the directional trend 

of the zooecial tube from nearly parallel to perpendicular to the incrusted surface. In zoaria incrusting 

very irregular surfaces and those displaying an irregularly massive growth habit, a typical thin-walled 

growth may develop either in the neanic or ephebic 

zones. A single zoarium displays thin-walled development in one group of zooecia and not in adjacent 

zooecia, thus the attribute is given no taxonomic value.

In the ephebic region the zooecial walls vary in 

thickness from uniform to irregular within a zoarium. 

Some zooecial walls are sharply inflected at the point 

of attachment of the hemiphragms (pi. 2, fig. 1). 

Diaphragms in observed zooecia range from 0 to 6 and 

are commonly absent. Their distribution is so irregular within a zoarium that they are not. considered a 

measure of growth stage in this species. The first 

diaphragm may be connected to the first hemiphragm 

or occur well within the ephebic zone. The diaphragms are uniformly thin, planar to irregularly 

curved, and located between or connected to the hemiphragms. The hemiphragms are evenly and closely 

spaced on the proximal side of the zooecia, and provide a convenient measure of growth stage in this 

species and probably within the genus. They are 

planar to concentrically wrinkled and a few are known 

to be approximately semicircular in plan view. Probably all zooecia contain hemiphragms, but, because 

they originate on the proximal walls and extend about 

one third to one half way across the zooecial voids, 

the plane of a longitudinal section can not be expected 

to intersect hemiphragms in all zooecia. Mesopores 

are abundant and generally contain one to several 

thin diaphragms and no hemiphragms (fig. 22; pi. 2, 

fig. 2). A rare zooecium is limited to the ephebic

zone (bottom of the zooecium is formed by the earliest 

hemiphragm of the adjacent zooecium) but differs 

from a mesopore in possessing hemiphragms and a 

diameter comparable to surrounding zooecia.

In tangential view, the apertures range from polygonal to subcircular. Zooecial walls are amalgamate. 

Mesopores are abundant but their numbers may be 

extremely varied in different areas of the same tangential section. The mesopores are concentrated at 

corners of the zooecia either singly or in pairs and in 

some zoaria are abundant enough to encircle a few 

zooecia completely. Acanthopores are large and 

abundant, inflect the zooecial walls; and are not restricted to the corners of the zooecia.

The following table is based on 20 sectioned fragments from 20 zoaria. Sections from 54 zoaria of 

D. polymorphism were examined.

Minimum Maximum

Diaphragms in ephebic zone______--------- 0 6

Zooecia in 2 mm_____________.___________ 7}^ 11

Average diameter of zooecia per fragment

mm.- .17 .22

Diameter of megazooecia. _______-__do.._- ______ .30

Acanthopores pen zooecium. ______________ .9 3.1

Mesopores per zooecium_______-_--____._- .8 2.0

Ontogeny

Number of Width of ephebic 

hemiphragms zone 

(mm)

2-3 . 30- 32

. 42- 55

. 70

.75

1. 05

Types: Holotype USNM 133861 from USGS collection 

3564-SD; figured paratypes USNM 133859, 133860, 133862- 

133864.

Occurence: Ludlowville shale : Centerfield limestone member, USGS 3593-SD; Wanakah shale member as used by 

Buehler and Tesmer (in press), USGS-SD 3502, 3511, 3515, 

3518, 3524, 3526, 3558a, 3565, USNM collections (20), 1015; 

King Ferry shale member of Cooper (1930), USGS 3564-SD. 

Moscow formation: Portland Point member of Cooper (1930), 

USGS 3551-SD; Kashong member of Cooper (1930) ; USGS-SD 

3500, 3508, 3531, 3542, 3552 and 3558; Windom member, 

USGS-SD 3559, 3575. Localities range from Lake Erie to 

Cayuga Lake.

Genus CALACANTHOPORA Duncan

1939. Calacanthopora Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 235.

Type species. Oalacanthopora prima Duncan 1939.

Original definition. "Zoarium incrusting. Walls 

completely amalgamate, uniform in thickness. Diaphragms and mesopores absent. Acanthopores well 

defined, usually very large, numerous." (Duncan, 

1939).
44 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

Remarks. The genus displays stereotoechid walls 

(p. 30) and resulting broadly amalgamate appearance 

in tangential view. The generic concept is based on 

a single zoarium. It is possible that the thinness of 

the incrusting zoarium and the lack of diaphragms 

reflects an astogenetically young growth stage rather 

than taxonomic characters of specific and generic 

value. The problem can be solved only by investigation of additional Traverse collections, preferably 

topotype specimens, not now available.

Calacanthopora? senticosa Boardman, n. sp. 

Plate 1, figures 2-4

Diagnosis. Incrusting and possibly ramose species, 

ramose forms with hollow axial tube supporting 

zooecia; diaphragms few, remote; mesopores common; acanthopores abundant, uniformly spaced in 

zooecial walls.

Description. Zoaria are incrusting or ramose. Incrusting zoaria occur on crinoid columnals. Ramose 

forms, including the holotype specimen, possess a 

hollow axial tube. The wall of the tube also serves 

as a basal lamina for the zooecia, and it is corrugated 

with a regularity suggesting that the central tube was 

originally filled with a supporting structure possessing 

annulated ridges such as a crinoid stem. > If a supporting structure was present during the growth of the 

bryozoan colony, the zoarium is more properly considered incrusting. One incrusting specimen is continuous around the disarticulated end of a segment 

of crinoid columnals indicating the bryozoan grew 

after the death and disarticulation of the crinoid. 

Abundant acanthopores produce a spinose texture to 

the external view, Monticules are unknown.

In the neanic region, the basal laminae and the 

zooecial walls vary considerably in thickness, even 

within a single fragment. The thickness of the two 

structures is proportional in any one zooecium. Thick 

neanic walls have a leptotrypellid appearance (p. 32) 

and a noticeable zooecial lining and sharp zooecial 

boundary. Distal to the zooecial bend, however, the 

Avail structure becomes stereotoechid (p. 30) and tangential sections all have stereotoechid characteristics. 

In a few zooecia, the acanthopores can be followed 

down into the neanic region, an uncommon condition 

in the Trenpostomata.

In the ephebic zone^, zooecial walls are relatively 

straight and uniform in thickness. Zooecial boundaries are not discernible; the laminae from adjacent 

zooecia appear to be continuous. Acanthopores begin 

either in the neanic zone or at the boundary between 

the neanic and ephebic zones. Diaphragms are few 

(maximum of 3 observed) and are lacking in the

relatively undeveloped zoaria. If present, the diaphragms are generally widely and irregularly spaced, 

uniformly thin, and planar to slightly curved. Diaphragms are less common in the mesopores.

In tangential view, zooecial apertures are generally 

subcircular. Mesopores are very small and are normally clustered at the zooecial corners in groups of 

one to three. Apertures of the mesopores are subcircular to subpolygonal. Acanthopores are extremely 

abundant and are uniformly and closely spaced in the 

zooecial walls. The acanthopores are relatively large, 

generally causing inflection of the zooecial walls, and 

many possess large central tubes.

The following table is based on 5 sectioned fragments from 5 zoaria. Sections from 7 zoaria of C. ? 

senticosa were examined.

Minimum Maximum 

Zooecia in 2 mm_________________________ 9 11

Average diameter of zooecia per fragment

mm__ .14 .17 

Acanthopores per zooecium. ___________'___ 5.0 5.8

Mesopores per zooecium._________________ 1.0 1.8

Remarks. No described genus seems suitable for 

the placement of CA senticosa. Dyscritella Girty 

(1911, p. 193) first described from the Fayetteville 

shale of the Chester series is a remote possibility and 

subsequent investigation of possible stratigraphically 

intervening species may display morphologic transition indicating phylogenetic connections.

The type species of Calacanthopora is not well 

enough understood to warrant expansion of the generic 

concept to include C. ? senticosa without reservation. 

However, joint possession of stereotoechid Avail structure in combination AA-ith abundant acanthopores in 

early growth stages, and general similarity in appearance of young incrusting zoaria of C. ? senticosa AA'ith 

that of C. prima, indicate the possibility of a generic 

relationship.

Types: Holotype USNM 133854, from USGS collection 

3502-SD; figured paratypes 133855, 133856.

Occurrence: Wanakah shale member (as used by Buehler 

and Tesmer) of the Ludlowville shale, USGS 3502-SD, Buffalo 

quadrangle.

LEIOCLEMID GROUP

Species from the Hamilton group that display the 

distinctive leioclemid.Avail structure are limited to the 

genus Leioclema. The Avail structure is characterized 

by Avell-defined groups of laminae in loosely or irregularly packed superposition; the laminae closely parallel the longitudinal directions of the zooecia for short 

but appreciable distances before curving into the 

zooecial boundaries (see p. 30, and fig. 10).
SYSTEMATIC DESCRIPTIONS 45

Genus LEIOCLEMA Ulrich

1882. Leioclema Ulrich, Cincinnati Soc. Nat. History Jour., 

v. 5, pt. 1, p. 141, 154.

1883. Thallostigma Hall, Albany Inst. Trans., v. 10, p. 154.

1890. Leioclema Ulrich, Illinois Geol. Survey, v. 8, pt. 2, p. 

376, 425.

1896. Lioclema (Objective synonym) Ulrich, Zittel's Textbook of Paleontology (English ed.) p. 277.

1900. Lioclema Nickles and Bassler, U. S. Geol. Survey Bull. 

173, p. 33.

1904. Lioclema Ulrich and Bassler, Smithsonian Misc. Coll., 

v. 47, p. 38.

1934. Lioclema Bassler, Fossilium Catalogus, I: Animalia, 

Pars 67, p. 140.

1949. Leioclema Duncan, Washington Acad. Sci. Jour., v. 39, 

no. 4, p. 131.

Type species. Callopora punctata Hall, 1858. 

Definition. "Zoarium ramose, lamellar, subglobose, 

or incrusting; surface frequently exhibiting distinct 

monticules or maculae; zooecia with subcircular or 

irregularly petaloid apertures, separated by abundant 

angular mesopores, which in some species are open at 

the surface, in others closed; diaphragms few in the 

zooecia, abundant, and sometimes crowded in the mesopores ; acanthopores numerous and strong in the typical species, small and inconspicuous in others." 

(Nickles and Bassler, 1900, p. 33).

In some species of Leioclemena (L. confertiporwn-} 

mesopores within the neanic region present a vesicular appearance strikingly similar to that of fistuliporoid bryozoans. However, these species retain 

the wall structure and other characters of the 

Trepostomata.

The following are species of Leioclema from the 

Hamilton group or its equivalents that were restudied 

or newly named.

alpenense Duncan 1939, p. 248, pi. 16, figs. 16-18 

confertiporum (Hall) 1883 

L. monroei (Ulrich and Bassler 1904, included

in synonymy.

decipiens (Hall) 1883 (Redescribed on p. 47). 

L. attenuatum Duncan 1939, included in synonymyL. traversense Duncan 1939, included in synonymy.

elasmaticum Boardman, n. sp. 

incompositum Duncan 1939, p. 250, pi. 15, figs. 4-6 

passitabulatum Duncan 1939, p. 251, pi. 16, figs. 

8-10

L. microporum (Hall) 1883, p. 186 and L. segrega.twn (Hall) 1883, p. 186 appear to belong to Leioclema from external characters but the primary types 

are too small for sectioning and the specimens cannot 

be compared at the species level.

50S925 O GO 8

Z. multaculeatum (Hall) 1884, p. 23, was first illustrated in Hall and Simpson (1887, pi. 59, figs. 10, 11) 

and appears to be a typical Leioclema. However, thin 

sections of the primary type (N.Y.S.M. 747) were 

studied and that specimen is not Leioclema. Generic 

identification cannot be made, however, because the 

sections were too fragmentary and the generic assignment of the species therefore remains in doubt.

The following Hamilton species were placed in 

Leioclema by Nickles and Bassler in 1900. A restudy 

of the primary types, however, indicates that they are 

fistuliporoids and do not belong <in Leioclema.

Fistulipora involvens>13.all and Simpson 1887, p. 

221, pi. 59, fig., 2

Thallostigma densa Hall 1883, p. 186

T. digitata Hall 1883, p. 185

T. subtilis Hall 1883, p. 187

Leioclema confertiporum (Hall) 

Plate 3, figures 1-3

1883. Thallostigma confertipora Hall, Albany Inst. Trans., v.

10, p. 184. 

1887. Fistulipora confertipora (Hall), Hall and Simpson,

New York State Geol. Survey, Palaeontology, v. 6,

p. 211, pi. 58, figs. 1-5. 

1897. Fistuliporina confertipora (Hall), Simpson, New York

State Geologist Annual Kept. 14, pi. 21, fig. 13.

(Plate description wrongly lists the species as coming from the lower Helderberg group, near Clarksville, N.Y.). 

1900. Lioclema confertiporum (Hall), Nickles and Bassler,

U. S. Geol. Survey Bull. 173, p. 303. 

1904. Lioclema monroei Ulrich and Bassler, Smithsonian

Misc. Coll. (Quarterly Issue), v. 47, no. 1470, p. 39,

pi. 11, figs. 10-12.

Diagnosis*, A Leioclema- of incrusting, irregularly 

massive, or subramose growth habit, distinguished by 

fistuliporoid-like vesicular structure of mesopores in 

neanic zones and strong and irregular thickening of 

mesopore and zooecial walls in ephebic zones.

Description. Zoaria are incrusting, irregularly massive, and subramose. In incrusting and massive 

forms, layers of overgrowth are common. Individual 

layers are as much as 7 mm thick and a complete 

zoarium is as much as 25 mm high. The basal 

laminae of many overgrowths are laterally discontinuous within a zoarium. Beyond the areas of the 

overgrowths, the zooecia are continuous. However, 

their walls commonly change abruptly from a thickwalled ephebic development to a thin-walled neanic 

growth at the levels of adjacent basal laminae. The 

incrusting zoaria occur on crinoid columnals and 

fistuliporoid bryozoans. <'

The subramose zoaria resulted largely from a modification of the incrusting growth habit. A branch con-
46 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

sists of a series of incrusting layers or overgrowths. 

These layers thicken over the end of the branch, thus, 

the length of the branch was increased more rapidly 

than the diameter and a short, thick branch was produced. New thin-walled growth without the formation of a basal lamina of an overgrowth also occurred 

in neanic zones following abandoned growing tips, as 

is more common in the ramose growth habit. Cyclic 

growth without a basal lamina is not common in the 

species however, and thus not considered to be of 

primary importance in branch formation in the species. 

Monticules are widely spaced and low. The included 

zooecia have diameters comparable to intermonticular 

zooecia but possess strongly thickened walls. Mesopores are less numerous in the monticules than in surrounding areas. The space between the monticular 

zooecia is largely occupied by strongly thickened deposits of the zooecial walls. Acanthopores are more 

abundant within the monticules and are extremely 

variable in diameter, ranging from 0.01 to 0.10 mm.

In incrusting arid massive zparia, thin-walled neanic 

regions extend distal to the zooecial bends for varying 

distances. Typically, the mesopores originate at the 

zooecial bend as uniserial chains of thin-walled, 

irregularly ovidal or spherical chambers. Several 

adjacent mesopores resemble the vesicular structure 

of fistuliporoid Bryozoa. Less commonly mesopores and zooecia do not develop thin-walled zones 

distal to the zooecial bends, but display thick-walled 

ephebic growth immediately beyond the bends.

In subramose zoaria, the neanic regions are repeatedly interrupted by closely spaced remnants of 

abandoned growing tips that are generally followed 

by basal laminae of overgrowths or less commonly by 

continuous 'but thin-walled zooecial growth. The beginning vesicular structure of mesopores is common 

just proximal to "-the abandoned growing tips giving 

the neanic region" a more vesicular and less tubular 

appearance than is common in most ramose trepostomes. Zooecial walls are also irregularly undulating, 

further adding to the vesicular appearance. Proximal 

ends of hew zooecia "are generally blunt and centered 

on walls separating parent zooecia.

The beginning of the ephebic zone in all growth 

forms is marked by a thickening of the zooecial walls 

and thick, planar, closely and regularly spaced diaphragms in the mesopores. The ephebic walls of the 

zooecia and mesopores are irregularly and strongly 

thickened. The wide variation in wall thickness is 

unusual for the -genus and is considered a specific 

character. Diaphragms within the zooecia are thin; 

commonly they are wanting but as many as three 

were observed in some tubes.

In the tangential view, zooecial apertures are subelliptical to subcircular. Each zooecium is ordinarily 

surrounded by 1 or 2 rows of mesopores. In addition, 

mesopores occur in clusters of 4 or 5 between symmetrically arranged groups of four zooecia. The 

apertures of the mesopores are subpolygonal, rarely 

subcircular. Mesopores are generally smaller than the 

zooecia, but a few are larger and are irregularly 

elongate in cross section. Acanthopores are common 

and concentrated around zooecial apertures. They are 

extremely variable in diameter and have large, central 

tubes.

The,following table is based on 9 fragments from 7 

incrusting and massive zoaria of L. confertiporum. 

Sections from 8 incrusting and massive zoaria were 

examined.

Two parattipe* and four

identified specimens Lectotype 

784 Minimum Maximum

0

7.2

. 17

10

. 23

Zooecial diaphragms _____________ 1-3

Mesopore diaphragms per mm 

ephebic zone __________________ 10

Average diameter of zooecia per

fragment-________----___mm__ .20

Average diameter of mesopores

per fragment_---------___mm__ .09 .09 .14

Acanthopores per zooecium_ ______ 2.3 1.3 2.0

Mesopores per zooecium________._ 3.2 2.6 4.3

Ontogeny of incrusting and massive zoaria

Number of Width of ephebic

diaphragms zone

in mesopores (mm)

5 0.5

8-9 1. 0

Lectotype____-_____-___-.___-------- 12 1.2

13 1.5-1.8

16 2. 1

The following table is based on 7 fragments from the 

6 subramose zoaria of L. confertiporum available for 

study, in addition to the holotype of L. monroei.

 Holotype Identified specimens 

Leioclema monroei Minimum Maximum 

Diameter of zoarium________mm__ ______ 6.2 7.8

Width of neanic zone_______do____ ______ 4.6 6.5

Zooecial diaphragms_____________ 0-1 0 3

Mesopore diaphragms per mm

ephebic zone. ________--.___-_- 10 7.5 10

Average diameter of zooecia per

fragment. _-____.____-___mm__ .20 .20 .20 

Average diameter of mesopores per

fragment_________-_---__mm__ .10 .06 .12

Acanthopores per zooecium. ______ 1.3 1.2 2.0

Mesopores per zooecium______.___ 3.2 2.0 4.0

Ontogeny of subramose zoaria

Leioclema monroei.

Number of Width of

diaphragms in ephebic zone Axial ratio

mesopores (mm)

6 1. 2 -____--_

6

7

12

1. 3-1. 6 

1. 4

2.4

. 74-. 83 ."81
SYSTEMATIC DESCRIPTIONS 47

Remarks. The subramose growth habit is known 

only in the Centerfield limestone member. The incrustinjr and massive growth habits occur in the o o

Wanakah shale and Tichenor limestone members. Not 

enough zoaria are available for study, however, to 

rule out the possibility of one or all three of the 

members containing both incrusting and subramose 

forms. The zooecia of both growth habits are alike 

in qualitative and quantitative characteristics. Incrusting overgrowths of subramose zoaria can not be 

distinguished from zoaria that are completely incrusting. Also, the subramose growth habit apparently arises from a slight modification of the incrusting growth habit.

Hall's syntypes of L. confertiporum appear to be 

incrusting but available fragments are so small that 

the lectotype could be subramose. The stratigraphic 

occurrence within the Hamilton group of Hall's specimens is not known. The holotype of L. monroei, 

here considered a junior subjective synonym, is subramose and its stratigraphic occurrence within the 

Hamilton group is also unknown.

L. confertiporum is readily distinguished from other 

species of Leioclema by the thick zooecial walls, especially in the monticules, and the vesicular appearance 

of the mesopores in the neanic region.

Types: Lectotype NYSM 734 (Hall and Siinpson 1887, pi. 

58, fig. 2) from the Hamilton group, Moscow, New York; 

figured specimens USNM 133865, 133866.

Occurrence: Ludlowville shale: Centerfield limestone member, USGS-SD, 3503, 3528; Wanakah shale member as used by 

Buehler and Tesner (in press), USGS-SD 3502, 3558a, USNM 

collection 1011. Localities range from Lake Brie to Seneca 

Lake. The locality for the holotype specimen of L. monroei 

is Hamilton group, Bethany, New York.

Leioclema decipiens (Hall) 

Plate 4, figures 1-4

1883. Thaltostiffma decipiens Hall, Albany Inst. Trans., v.

10. p. 187. 

1887. Fistulipora decipiens (Hall), Hall and Simpson, New

York State Geol. Survey, Palaeontology, v. 6, p. 232,

pi. 59, fig. 9. 

1900. Lioclema decipiens (Hall), Nickles and Bassler, U. S.

Geol. Survey Bull. 173, p. 303. 

1939. Lioclema attenuatum Duncan, Univ. Michigan Mus.

Paleontology, Contr., v. 5, p. 249, pi. 16, figs. 13-15. 

1939. Lioclema traversense Duncan, ibid., p. 252, pi. 16, figs.

11. 12.

Diagnosis. Zoaria thin lamellar expansions, a few 

incrusting; in neanic region, mesopores thin-walled 

and divided into elongate, angular compartments by 

tabular diaphragms; in ephebic zone, zooecial walls 

moderate and uniform in thickness.

Description. The zoaria assume the thin lamellar 

expansions of the incrusting growth habit but their

basal laminae most commonly rest directly on the 

matrix of the inclosing mudstones and siltstones. The 

expansions display irregularly curved and undulating 

contortions. A few zoaria are incrusting directly on 

other fossils for at least part of their area. Incrusted 

forms include brachiopods, corals (auloporoids and 

Pleurodictyum) and fistuliporoid, fenestellid and 

trepostomatous Bryozoa. Overgrowth is common although most zoaria show single growth cycles, or 

layers of mud between thin zoarial layers that cannot 

always be demonstrated to be continuous, so might be 

separate incrusting zoaria. Monticules are inconspicuous and are merely suggested by groups of zooecia with 

slightly thicker walls, differing concentrations of mesopores, or larger acanthopores.

In the neanic zone, zooecial tubes begin in the 

normal recumbent position of the incrusting growth 

habit. The neanic zone extends distally at least to the 

sharp zooecial bend and in some zooecia and mesopores 

it extends beyond the bend for varying distances if 

walls remain thin. Mesopores begin at the zooecial 

bends. If thin walled in the beginning, they are 

normally divided into elongate angular compartments 

by thin tabular diaphragms. The compartments appear sharply rectangular in sections. In parts or 

throughout some zoaria thicker walled ephebic growth 

follows the bends directly.

In the ephebic zone, zooecial walls are variable in 

thickness in different zoaria and never develop more 

than moderate thicknesses (0.04 mm). Wall thickening, in a zooecium is fairly uniform. Zooecia are 

generally without diaphragms and no more than three 

were observed. Mesopores develop closely and regularly spaced diaphragms that are variable in thickness but generally thinner than surrounding mesopore 

and zooecial w^alls.

In tangential sections, zooecial apertures are subcircular to suboval. Mesopore apertures are subpolygonal to subcircular, and their average diameter is 

half or slightly more than half the diameter of the 

zooecia. Mesopores generally surround zooecia in 

single rows and also occur in clusters of 4 to 6 in 

larger, regularly spaced interzooecial areas. Acanthopores are common, and concentrated around zooecial 

apertures, generally causing some inflection of the 

walls. They are extremely variable in diameter and 

have large central tubes.

The following table is based on 16 fragments from 

14 zoaria. Sections from 24 zoaria of L. decipiens 

wero examined. (Above figures do not include the 

holotype of L. decipiens and the holotype of L. 

traversense).
48

Holotype Identified specimens ' Holotype Leioclema 

757 traversense Minimum Maximum

Zooecial diaphragms...-. 000 3 

Mesoppre diaphragms per

mm ephebic zone _--_..- 10 7.1 7.1 10 

Average diameter of zooecia per fragment__mm__ .17 .17 .17 . 20 

Average diameter of mesopores per fragment

mm.. .14 .09 .09 .12 

Acanthopores per zooecium.....-.-_-.-_---- 1.3 2.1 .5 2.5 

Mesopores per zooecium__ 3. 1 3. 1 3. 5 6. 0

Ontogeny

Number of Width of 

diaphragms in ephebic zone 

mesopores

Holotype 737. __-_., 

Leioclema traversense.

(mm) 

0..20 

.42 

40-. 41 

.60 

61-. 70 

.70

Remarks. L. attenuatum Duncan 1939, is considered to be a young growth stage of L. decipiens: the 

holotype displaying 1 to 2 mesopore diaphragms in the 

ephebic zone and no important differences in the tangential section.

Zoaria that display the angular compartments of 

mesopores in neanic zones and other morphologic 

characteristics of L. decipiens as here described occur 

in two collections (3502 and 3558a) of the Wanakah 

shale with zoaria that contain vesicular mesopores and 

are assigned to L. confertiporum. Zoaria displaying 

transitional morphologic characteristics were not found 

so the species are considered distinct.

Types: Holotype NYSM 737, Hamilton group, York, New 

York; figured specimens USNM- 133867-133869.

Occurrence: Ludlowville shale: Wanakah shale member as 

used by Buehler and Tesmer, USGS-SD 3502, 3511, 3516, 

3518, 3558a, 3565; King Ferry shale member of Cooper (1930) 

USGS 3582-SD. Moscow shale: Kashong member of Cooper 

(1930),' USGS-SD 3500, 3552, 3556, 3558. Collections range 

from Lake Erie to Cayuga Lake. The holotype of L. traversense Duncan is from the Norway Point formation, Michigan. 

The holotype of L. attenuatum Duncan is from the Potter 

Farm formation, Michigan.

Leioclema elasmaticum Boardman, n. sp.

Plate 4, figures 5-8

Diagnosis. Zoaria thin lamellar expansions, basal 

laminae directly on rock matrix; doubtful monticules 

indicated by few acanthopores in isolated zooecial 

groups, intermonticular areas without acanthopores. 

Description. The zoaria assume the thin lamellar 

expansions of the incrusting growth habit but their 

basal laminae rest directly .on the inclosing mudstones

and siltstones. The expansions display irregularly 

curved and undulating contortions. Overgrowth is 

fairly common although most zoaria consist of single 

growth cycles or contain layers of mud between thin 

expansions. The presence of monticules is uncertain 

and is suggested only by small isolated groups of 

zooecia and mesopores that display acanthopores. 

Acanthopores are completely lacking or very rare between the questionable monticules.

The neanic zone begins with the thin laminated walls 

of the recumbent zooecia branching from the basal 

laminae, as in the normal incrusting growth habit. The 

neanic zone extends at least to the sharp zooecial bend 

and in a few zooecia and mesopores extends beyond 

the bend for short distances if walls remain thin. 

Mesopores begin at the zooecial bends.

The few mesopores that start with thin walls develop 

as many as three irregular chambers. Most mesopores 

start with thickened walls and closely and evenly 

spaced diaphragms, marking the beginning of the 

ephebic zone. The thickness of the mesopore diaphragms varies, generally in proportion to wall thickness. In the ephebic zone there is much variation in 

the thickness of zooecial walls in different zoaria or in 

parts of the same zoarium. However, the extremes 

are linked by forms in which the walls are of intermediate thicknesses. The ephebic wall thickness of 

individual zooecia and mesopores, however, is fairly 

uniform. Diaphragms in the zooecia are thin and uncommon ; no more than one occurs in a zooecium in the 

specimens studied.

In tangential sections, zooecial apertures are subcircular to suboval. The apertures of the mesopores 

are normally subpolygonal, rarely subcircular, and 

are generally smaller than the zooecial apertures. A 

few mesopores are larger than the zooecia, and these 

are commonly irregularly elongate in cross section. 

Mesopores generally surround zooecia in single rows 

and also occur in clusters of 4 to 8 in larger, regularly 

distributed interzooecial spaces. Acanthopores normally do not occur; those found are in concentrated 

areas that might represent monticules and are of small 

to medium size.

The following table is based on 12 fragments from 

the 11 zoaria of L. elas'tnaticum available for study.

Minimum Maximum

Mesopore diaphragms per mm ephebic zone. 6. 8 8. 7 

Average diameter of zooecia per fragment

mm.. .17 .20 

Average diameter mesopores per fragment

mm.- .09 .14 

Mesopores per zooecium____________-_---- 3. 4 5. 7
SYSTEMATIC DESCRIPTIONS 49

Ontogeny

Number of 

diaphragms in 

mesopores

2

3

4

5-6

11

Width of 

ephebic zone

0. 29

. 35- 44

.48

. 70

1.26

Remarks. The restriction of acanthopores.to questionable monticules that are otherwise undifferentiated 

from intermonticular areas distinguishes L. elasmaticiim from all other species of Leioclema in the Hamilton group and the Traverse group of Michigan.

Types: Holotype USNM 133870 from USGS collection 

3559-SD; figured paratypes USNM 133871-133873.

Occurrence: Moscow shale: Windom member, USGS-SD 

3548, 3553, 3559. Collections range from the Genesee Valley 

to Seneca Lake.

TRACHYTOECHID GROUP

Genera from the Hamilton group that display 

zooecial wall structure similar to that of the genus 

Trachytoechus Duncan, are placed together. The 

zooecial wall laminae of the included genera parallel 

the longitudinal direction of the zooecia for appreciable distances before curving distally to the zooecial 

boundaries. Zooecial walls contain mural lacunae and 

the thin walls of neanic zones are crenulated. (See 

p. 31 and figure 11).

Genus TRACHYTOECHUS Duncan

1939. Trachytoechus Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 261.

Type species. Trachytoechus typicus Duncan 1939.

Emended definition. Zoaria are massive, incrusting, 

and subramose. Groups of larger zooecia are characteristic but are not elevated above the zoarial surface 

in some species. In the ephebic region, zooecial walls 

normally range from flexuous to crenulated. Diaphragms are uniformly thin, complete, and planar to 

curved. Heterophragms are characteristic of the genus 

and are curved projections of laminated material 

originating in the zooecial Avails and projecting into 

the zooecial voids. They are subcircular in plan view 

and are normally concave in the proximal direction 

of the zooecia. Margins of the heterophragms are 

smooth or corrugated. In tangential view, the walls 

are amalgamate and commonly display mural lacunae 

that are either uniformly distributed, or clustered to 

appear as small granular acanthopores. The zooecial 

walls may present an overall granular appearance if 

the lacunae are filled with opaque material. In some 

species the lacunae are rare. Acanthopores are generally large and laminated. Mesopores are rare.

Remarks. Cyphotrypa expanda Ulrich and Bassler 

(1923, p. 407, pi. 13, figs. 5-9) and Stenoporaf incrustans Ulrich and Bassler (1913 a, p. 275, pi. 42, 

figs. 11-16; pi. 44, fig. 6) possess trachytoechid wall 

structure and typical heterophragms and are here reassigned to Trachytoechus. T. expandus extends the 

known stratigraphic range of Trachytoechus downward to the Tonoloway limestone of Late Silurian age. 

The holotype section of Eostenopora? villosa Duncan 

(1939, p. 247, pi. 11, figs. 1, 2; pi. 12, fig. 15) displays 

typical trachtoechid wall structure, large acanthopores, 

and a very few heterophragms. The holotype specimen of E.f villosa comes from the same collection 

(Bell shale, locality 38) as Trachytoechus. typicus 

Duncan (1939, p. 263, pi. 13, figs. 1-6) and differs morphologically only in having fewer heterophragms and 

a younger growth stage. Assuming that the growth 

stage of the holotype specimen of E.f villosa is not 

far enough advanced to develop many heterophragms 

(generally concentrated in ephebic zones) E.? villosa is 

here placed in the synonymy of T. typicus. Eostenopora primiformis Duncan (1939, p. 245, pi. 12, figs. 

9-10) is considered a young growth stage and is placed 

in the synonymy of Trachytoechus romingeri Duncan 

(1939, p. 262, pi. 13, figs. 7-9).

The following species have been restudied and are 

considered to be species of Trachytoechus.

expandus (Ulrich and Bassler) 1923, Tonoloway limestone, West Virginia.

howelli Fritz 1951, p. 28, 29; pi. 1, figs. 1, 2; pi. 2, fig. 1. 

New Scotland limestone, New York.

incrustans (Ulrich and Bassler) 1913, Keyser limestone 

member of Helderberg limestone, Maryland.

moniliformis Fritz I944b, p. 36, 37, pi. 1, flgs. 1-4, Gaspe 

sandstone, Quebec.

monticulatus (Hall) 1879, Helderberg group, New York. 

Reassigned to Trachytoechus by Fritz, 1951.

romingeri Duncan 1939, probably from the Genshaw formation, Michigan. Eostenopora primiformis Duncan, 1939, 

included in synonymy. Dock Street clay, Michigan.

typicns Duncan 1939, Bell shale, Michigan. Eostenopora? 

villosa Duncan 1939, included in synonymy.

variaccllns (Hall) 1883 Centerfleld limestone member of the 

Ludlowville shale, New York.

Trachytoechus variacellus (Hall) 

Plate 5, figures 1-3

1883. Paleschara variacella Hall, Albany Inst. Trahs., v. 10, 

p. 179.

1884. Paleschara variacella Hall, New York State Geologists 

Annual Kept, for 1883, p. 6.

Diagnosis. Irregularly hemispherical Trachytoechus; megazooecia extremely large in diameter; .large 

acanthopores with abrupt changes in diameter to form 

club-shaped segments in longitudinal section; generally
50 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

few mural lacunae; heterophragms rare, few corrugated.

Description. Zoaria begin as incrusting forms that 

developed into irregularly hemispherical to subspherical masses as much as 9 cm in height and 15 cm in 

diameter. Internally, the zoaria display patchy and 

irregularly spaced overgrowths that form superinir 

posed layers. Many basal laminae of the overgrowths 

do not extend throughout a zoarium but are discontinuous. The margins of the restricted laminae abut 

against adjacent uninterrupted zooecia. Some patchy 

overgrowths thicken markedly and produce bulbous 

protuberances on the main zoarium. Monticules are 

either very low or without surface expression. Included megazooecia are extremely large in cross section (as much as three times larger than intermonticular zooecia) and display little wall thickening. 

Acanthopores are unmodified in the monticules.

Neanic and ephebic zones are not clearly delimited. 

Zooecia begin by budding from the normal basal 

lamina and are in a recumbent position. Distal to the 

zooecial bends, zooecial tubes are extremely long and 

show alternations of slightly thicker walled growth 

with more closely spaced diaphragms and a relative 

concentration of heterophragms, and thin-walled 

growth showing widely spaced diaphragms and few if 

any heterophragms. This thin- and thick-walled 

growth occurs in zones approximately parallel to the 

surface of the zoarium and affects varying numbers of 

zooecia. The zooecial walls range from straight, to 

undulate, to crenulate within a zoarium. Zooecial wall 

laminae begin by paralleling the longitudinal direction of the zooecia without forming a distinct zooecial 

lining. The zone of curved laminae is relatively broad. 

A poorly denned zooecial boundary meanders irregularly throughout the zone of curved laminae. Zooecial 

diaphragms are very thin,'--'planar to slightly curved, 

and irregularly spaced. Diaphragms of the megazooecia are more strongly curved and are commonly 

cystoidal. Granular deposits of pyrite are commonly 

associated with diaphragms in both the normal zooecia 

and megazooecia in many zoaria (pi. 5, fig. 2b). Acanthopores are long and club-shaped in longitudinal section and regularly decrease their diameters abruptly 

(pi. 5, fig. 3b) producing transverse planes of discontinuity that commonly fracture iu, thin sections. 

Heterophragms are generally few but may be abundant 

locally in zones of thickened zooecial walls. The 

heterophragms are rarely corrugated.

In tangential section, the zooecial apertures are 

polygonal to subpolygonal and generally equidimensional. The megazooecial apertures are more elongated 

in cross section. Mesopores are very rare throughout

a zoarium. Zooecial walls are amalgamate, laminated, 

and mural lacunae are uncommon. Acanthopores are 

large and are always located at the corners of zooecia. 

Their outer boundaries are subrectangular or subtriangular, and the acanthopores have large central tubes 

that are commonly filled with laminated material.

The following table is based on 17 fragments from 

13 zoaria. Sections from 18 zoaria of T. variacellus 

were examined.

Holotype Identified specimens 

8S7 Minimum Maximum

Diaphragms per 5 mm ephebic zone. 

Zooecia in 2 mm.._______________

Average diameter of zooecia per

fragment. _________-j___ _ _mm_ _

Maximum diameter of megazooecia

per fragment___.-._______mm__

Acanthopores per zooecium. ______

13

6

. 34

.72 

. 12

9

5

. 29

.60 

. 10

21

.38

.90 

.44

Remarks. T. variacellus can be distinguished immediately from other described species of Trachytoechus by the large club-shaped acanthopores.

Types: Holotype NYSM no. 827, Hamilton group, New York; 

figured specimens USNM 133874, 133875.

Occurrence: Ludlowville shale: Centerfield limestone member, USGS-SD 3503, 3539, 3547a, 3561, 3571. Collections range 

from the Batavia quadrangle to Cayuga Lake.

Genus ERIDOTRYPELLA Duncan

1939. Eridotrypella Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 210.

Type species. Batostomella obliqua Ulrich 1890.

Original definition. "Zoarium ramose. Wall structure heterotrypid-amalgamate; transverse rows of 

granules well defined. Walls thin, usually crenulated 

in immature region, gradually thickened from beginning of mature zone to surface. Zooecia oblique, 

slightly bent toward surface in mature zone. Diaphragms absent in immature zone, several closely arranged in early mature zone of each zooecium, usually 

absent near periphery. Mesopores absent. Acanthopores granular." (Duncan, 1939).

Eridotrypella sp. 

Plate 1, fig. 5

A single, partly crushed fragment of a ramose 

zoarium was recovered from collection 3553 in the 

Windom member of the Moscow shale on Menteth 

Creek, Canandaigua Lake. This specimen is the only 

known occurrence of the genus in the New York 

Hamilton group. The scarcity of the genus in New 

York is in marked contrast to its prolific abundance 

in the Traverse group of the Michigan basin. The 

specimen is too poorly preserved for comparison but 

does seem to differ from Michigan species by display-
SYSTEMATIC DESCRIPTIONS 51

ing only one diaphragm in an ephebic zone that is comparable in width with ephebic zones of Michigan 

forms containing 3 to 5 diaphragms.

Type: Figured specimen USNM 133857. 

LEPTOTRYPELLID GROUP

Genera from the Hamilton group that display 

zooecial wall structures similar to that of the genus 

Leptotrypella Vinassa de Kegny, are placed together. 

The wall structure is characterized by a zooecial lining 

and a zone of curved laminae. The zooecial lining extends distal]y for considerable distances and commonly can be distinguished as a layer of lighter shaded) 

laminae in thin section. Laminae of the lining either 

lose their identity distally or can be traced outward 

into the zone of curved laminae. The curved laminae 

are generally darker and intersect the zooecial boundary at right angles. (See p. 32 and fig. 12).

Genus LEPTOTRYPELLA Vinassa de Regny

1920. Leptotrypella Vinassa de Regny, Atti. Soc. italiana sci. 

nat, v. 59, p. 222.

1939. Leptotrypetta Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 223.

Type species. Chaetetes barrandi Nicholson 1874.

Emended definition. Zoaria are ramose, subramose, 

incrusting, or a combination of ramose and incrusting 

habits. Conspecific overgrowth is common. Monticules are present and normally include megazooecia, 

mesopores, and enlarged acanthopores. In most 

species, a zooecial lining can be distinguished, and the 

laminae parallel the zooecia for a considerable distance 

in all species. Diaphragms are complete; cystoidal 

diaphragms vary in number but are common in most 

species, and compound diaphragms occur in only a 

few species (p. 62). Mural spines are known in 

about half of the species and are extremely .variable 

in numbers within several species and typically rare 

or common in others. Spherical intrazooecial cysts 

are variable in concentration but are typical of the 

genus. In tangential view, zooecial boundaries are 

polygonal. Zooecial Avails are generally amalgamate, 

but a few species are narrowly amalgamate to integrate. Intermonticular mesopores are scattered and 

few, but in rare zoaria of a few species they are 

equal in number to the zooecia. Acanthopores are 

laminated, typically numerous, but nearly absent in a 

few species.

Remarks. Leptotrypella solitaria Fritz (1944, 

Jour. Paleontology, v. 18, no. 1, p. 36, pi. 12, figs. 10, 

16) is not referable to Leptotrypella as defined here 

because of the presence of strong irregular beading in 

the zooecial walls. The species was based on one small

fragment that does not adequately display the wall 

structure, although it appears to be atactotoechid. Nor 

is Leptotrypella cavernosa Fritz (1944, Jour. Paleontology, v. 18, no. 1, p. 37, pi. 12, figs. 6, 13) referable 

to Leptotrypella. This species has a definite atactotoechid wall and the type specimen is apparently a young 

growth stage that shows no generic characters. Holotype slides of both species were examined for this 

paper.

Subgenus LEPTOTRYPELLA Vinassa de Regny emend. Boardman

Type species. Chaetetes barrandi Nicholson 1874.

Definition. The subgenus includes those species of 

Leptotrypella that do not contain compound diaphragms. Characteristically, the diaphragms are 

simple, thin, planar to slightly curved, and evenly 

spaced. Cystoidal diaphragms range in abundance 

from very rare to common. Zooecial walls are typically amalgamate; narrowly amalgamate to integrate 

appearances are generally limited to scattered zooecia 

or monticular zooecia.

Remarks. The nominate subgenus is considered to 

include the main, conservative lineages of the genus. 

L. (Leptotrypella) is longer in stratigraphic range, 

wider in geographic range (fig. 4) and greater in 

number of species, than L. (Pylenobasis) (p. 62) the 

other subgenus of Leptotrypella.

Stenoporella? devonica Duncan (1939, p. 259, pi. 

14, figs. 9-10) and Cyphotrypa? unica Duncan (1939, 

p. 201, pi. 5, figs. 11-14) are reassigned to L. (Leptotrypella) because of wall structure and diaphragms. 

Eridotrypella brevis Duncan (1939, p. 211, pi. 5, 

figs. 15-16) is considered a young growth stage of 

Leptotrypella ohioensis (Stewart) (1927, p. 29, pi. 2, 

figs. 7-10) and is referred to the synonymy of that 

species. Leptotrypella undans Duncan (1939, p. 231, 

pi. 10, figs. 4-6) is considered a young growth stage 

of Leptotrypella aequabilis Duncan (1939, p. 224, pi. 

9, figs. 6-7) and is placed in the synonymy of that 

species.

The species now assigned to L. (Leptotrypella) are:

aeguatrilis Duncan 1939.

L. undans Duncan 1939, included in synonymy. 

amplectens (Grabau) 1899 (Redescribed on p. 60).

Monticuliporaf marylandensis TJlrich and Bassler 1913,

included in synonymy. 

asterica Boardman, n. sp.

barrandi (Nicholson) 1874 (Redescribed on p. 53). 

devonica (Duncan) 1939.

furcatd (Hall) 1877 (part) (Redescribed on p. 59). 

gemmata Duncan 1939, p. 225, pi. 10, figs. 7-8. 

kivangsiensis Yang, 1954, p. 223, pi. 2, fig. 5; pi. 3, fig. 5. 

magninodosa Duncan 1939, p. 226, pi. 9, figs. 8-9. 

magniporta Boardman, n. sp.
52 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

mesostena Boardman, n. sp.

mesostena mesostena Boardman, n. subsp.

mesostena provecta Boardman, n. subsp. 

moniliformis (Nicholson) 1874, p. 57, pi. 4, figs. 7a, 7b. 

multitecta Boardman, n. sp. 

ohioensis (Stewart) 1927.

Eridotrypella ~brevis Duncan 1939, included in synonymy. 

parva Duncan 1939, p. 229, pi. 9, figs. 4-5. 

pellucida Duncan 1939, p. 230, pi. 10, figs. 9-10. 

unica (Duncan) 1939.

Inferred phylogenetic lineages in L. (Leptotrypella). The proposed L. mesostena-multitecta lineage 

(see p. 56) includes the intervening subspecies, Z. 

mesostena provecta (fig. 23). Qualitatively, the Z. 

mesostena-multitecta lineage displays the loss of fine 

crenulations in the neanic regions, a change of from 

3-4 to 2-3 diaphragms with a lessening of the constriction of the zooecial tubes in that zone in the

STRATIGRAPHIC 

OCCURRENCE

FORMATION

o> ~a 

10

o 

o

CO

o

shale Ludlowville 

^^^ MORPHOLOGY 

MEMBER ^\^

Windom

Kashong (of Cooper, 1930)

Portland Point 

(of Cooper, 1930)

Deep Run 

(of Cooper, 1930)

shale 

Tichenor limestone 

(of Cooper,

loom

Wanakah shale 

(as used by Buehler 

and Tesmer.in press)

Ledyard (of Cooper, 1930)

Centerfield limestone

Skaneateles shale equivalents 

in Michigan

Subgenus Leptotrypella

Simple diaphragms

Cystoidal diaphragms increase in abundance

1 _ furcata ____ ^

1 aste

aste

nca l

'"tea i Yniilti-tfirtn

/ '

/

/ provecta /

/ 

/ 

| ___ mesostena 

V__ | 

/ mesostena

/ 

Michig,

Leptotryj

f

in 

vella

Subgenus Pycnobasis

Simple and compound diaphragms

1 amphelicta 1 l polita i

/

/

/

/ i tuberata |

/

l amphelicta /pachyphragma i

/

FIGURE 23. Po&sible phylogenetic relationships of some of the species of the genus Leptotrypella.
SYSTEMATIC DESCRIPTIONS 53

early ephebic zone proximal to the zooecial bend, 

flattening of the zooecial bend, widening of the 

zones of curved laminae, and the change from a 

generally integrate to generally amalgamate appearance in tangential sections. Quantitatively, the 

diameters of the neanic regions become generally 

larger upwards in the lineage (see table below), making the axial ratios larger for corresponding growth 

stages (fig. 24). A very few specimens of L. multitecta contain some zooecia with the constriction in 

zooecial diameter just proximal to a sharp zooecial 

bend, giving the appearance of L. mesostena and 

further substantiating the proposed phylogenetic relationship.

Species of Leptotrypella and their neanic diameters, arranged in 

stratigraphic order.

Stratigraphic position

,.

0

^

03 

fc

C 

oj

bp

2

_o

"*

c3 5CO

53'£

_o

3

-2

J"3

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t/5

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05

Wanakah shale

member as

used by

Buehler and

Tesmer

Ledyard

member of

Cooper (1930)

Centerfield

limestone

member

Dock Street

clay of

Grabau (1902)

Genshaw

formation

Ferron Point

formation

Bell shale

Species of

Leptotrypella

L. multitecta

L. mesostena

provecta

L. mesostena

mesostena

L . moniliformis

L. magninodosa

L. aequobilis

L. pellucida

L. ohioensis

L. devonica

L. gemmata

Arithmetic mean of

neanic diameters (mm)

4.4 (31 zoaria)

3.5 (5 zoaria)

2.4 (23 zoaria)

Neanic diameter

(mm) of

holotype

specimens

2.9

2.0

2.0 and 2.3

5.1

2.8 and 3.0

2.6

1.4

Another possibility for the lineage or plexus that 

gave rise to L. niuliitecta is suggested by the study 

of the holotype sections of the species of Leptotrypella 

described by Duncan (1939) from the Traverse group 

of Michigan. All of the Traverse species came from 

formations now considered equivalent to the New York 

Skaneateles shale (Cooper and others, 1942). Assuming 

that this time-rock correlation is correct, and that there 

was at least an intermittent connection between the 

Michigan basin and the New York area, the Traverse 

species could have been forebearers of L. multitecta. 

QualitatiA^ely, there is little difference between L. multitecta from New York (p. 57) and L. devonica, L.

magninodosa, and especially L. aequoibilis from the 

Traverse group. Measurements of neanic diameters 

(table, p. 53) in the single holotype sections for each 

Traverse species suggests that the diameters were generally small in these older forms and increased with 

time to the Z. multitecta level. This suggested increase 

in neanic diameters is consistent with the trend found 

in the L. mesostena-multitecta lineage proposed above. 

Also, an evolutionary level probably more primitive 

(again on the basis of the trend found in L. mesostenamultitecta) than L, multitecta is indicated for the 

Traverse species by a plot of their axial ratios against 

the number of diaphragms (fig. 24). The scatter diagram indicates that the Traverse species are at about 

the same evolutionary level as L. mesostena mesostena 

and L. mesostena provecta. L. pellucida, a Traverse 

species, is an exception in these generalizations but 

could belong to another lineage. If the Traverse species do constitute the lineage leading to L. multitecta, 

L. mesostena mesostena and L. mesostena provecta 

probably are not intermediate subspecies, due to their 

qualitative characteristics that are not intermediate 

between the Traverse species and L. multitecta. A 

detailed study of a large number of specimens in the 

Michigan Traverse group will be necessary before these 

evolutionary and phylogenetic relationships are 

clarified.

L. (Leptotrypella) asterica (p. 58) appears to be 

directly related to L. (Leptotrypella) furcata (p. 59). 

Evidence for the lineage is found in the similarity of 

diaphragms, cysts, and zoarial size. Morphologic 

changes in the lineage include a widening of the zone 

of curved laminae and a decrease in the thickness of 

the zooecial lining, trends also present in the L. 

mesostena-multitecta lineage. The development of 

more crenulate walls in the younger L. furcata is a 

reversal of the trend of a decrease in crenulations in the 

L. mesostena-multitecta lineage. No appreciable differences in neanic diameters and axial ratios occur in 

the L. asterica-furcata lineage.

Leptotrypella barrandi (Nicholson) 

Plate 8, figures 1, 2

1874. Chaetetes barrandi Nicholson, Geol. Mag., dec. II of 

new series, v. 1, p. 57, pi. 4, fig. 7 c.

1881. Monticiilipora (Heterotrypa) barrandi (Nicholson), 

Genus Monticulipora p. 139, pi. 1, figs. 2-2d.

1882. Amplexopora barrandi (Nicholson) Ulrich, Cincinnati

Soc. Nat. History Jour., v. 5, p. 255. 

1920. Leptotrypella barrandei (Nicholson) Vinassa de Regny,

Atti Soc. italiana sci. nat, v. 59, p. 222.
54 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

EXPLANATION

Line bounding area of plotted points of L. multitecta, Wanakah 

shale; 48 fragments from 22 zoaria

Line bounding area of plotted points of L. mesostena provecta, 

Ledyard member: 4 fragments from 4 zoaria

Line bounding area of plotted points of /,. mesostena mesostena, 

Centerfield limestone member; 23 fragments from 20 zoaria

L. pellucida 

Perron Point formati L. devonica 

Bell shale

0.80 0.60 0.55 

AXIAL RATIO

FIGURE 24. Peripheral scatter diagram of the L. (Leptotrypella) mesostena to multitecta lineage and individual measurements of the holotype 

sections of species of Leptotrypella described by Duncan (1939) from the Traverse group of Michigan.

Description. Zoaria are ramose and conspecific 

overgrowth is probably common as the two available 

specimens (see remarks below) show remnants of 

abandoned growing tips covered by an incrusting overgrowth that gives rise to a branch in the distal direction. Monticules are not adequately displayed in the 

two sections.

In the neanic region, the zooecial walls are fairly 

straight and imdeviating. In the early ephebic zone, 

the zooecial bend is flat and poorly defined and the 

zooecia are not constricted in diameter as in Z. mesostena. In the ephebic region, the zone of curved laminae is broad and lighter in color than the thin zooecial 

lining. The zooecial boundary is poorly defined, most 

laminae from adjacent zooecia merging without apparent break. The diaphragms are simple, thin, planar 

to slightly curved, and fairly evenly spaced. Cystoidal 

diaphragms and cysts are rare, mural spines and cysts 

are unknown.

In the tangential section, the zooecial apertures are 

polygonal to subcircular. The walls are amalgamate 

to narrowly amalgamate and a few zooecia appear 

integrate. Mesopores are few and irregularly distributed. Acanthopores are unusually scarce for the 

genus and are small, causing almost no inflection in 

the zooecial walls.

Diameter of zoarium._____-_-__-_.__mmWidth of neanic zone_-----------_--do_--

Zooecia in 2 mm_______-._--____________.

Average diameter of zooecia per fragment

Acanthopores per zooeciumMesopores per zooecium-__.

Slide 1,

USNM 

86688

4. 4

1.8

8

. 23

. 3

Rare

Ontogeny

Slide

Number of 

diaphragms

5-7

6-8

Width of

ephebic zone

(mm)

2. 6

3. 7

Slide 2,

USNM

6. 2 

2. 5

7

. 20 

. 4 

. 1

Axial ratio 

. 41 

. 40

Remarks. The whereabouts of the holotype of L. 

barrandi is not known. Thin-sections of two fragments labeled L. barrandi (Nicholson) 1874, are available for study in the U. S. National Museum. One of 

them (USNM 26588) was used in the emended definition by Duncan (1939, p. 223). Both sections are 

from the Widder formation, Thedford, Ontario. 

Nicholson's original description (1874a, p. 57, 58) gives 

the locality and stratigraphic position as the Hamilton group at Widder, Township of Bosanquet. The 

town of Widder has nearly disappeared and the name 

is not now in use. The center of Widder was just 

over a mile east of the present center of the town of 

Thedford. The sections labeled Thedford in the U. S.
SYSTEMATIC DESCRIPTIONS 55

National Museum may be topotypes as nothing more 

specific than the town names is given in both the 

original description and the sections in the museum.

According to Nicholson's original description the 

diameters of the branches range from 2 to 5 lines 

(approximately 4 to 10 mm). Nicholson describes the 

monticules as not forming distinct eminences, "But 

here and there are groups of corallites slightly larger 

than the ordinary one, and separated by intervals of 

about a line and a half" (3 mm). The one characteristic reported by Nicholson in 1874 that does not 

agree with the National Museum specimens is the 

number of zooecia in 2 mm. Nicholson reported, 

"Four to five calices in the space of one line" (2.12 

mm). Nicholson's count is smaller than is normal for 

the genus and may have been taken through a monticule. Nicholson's original illustration is of no value 

in taxonomic interpretation.

In 1881 Nicholson added to the concept of the species by reporting that, "Small thick-walled hollow 

tubes (acanthopores) are occasionally developed at the 

angles of junction of the normal corallites." Also, he 

describes the diaphragms as complete and horizontal 

and the zooecial walls as amalgamated. The drawings 

of the tangential view of L. barrandi (1881, pi. 1, figs. 

2b, 2c) are adequate in detail and agree with the 

museum specimens in general appearance and in the 

unusual scarcity and small size of the acanthopores. 

Nicholson's vertical view (pi. 1, fig. 2d) is apparently 

of a poorly oriented section and is of little help.

L. barrandi is most nearly like L. multitecta (p. 57) 

among the species from the New York Hamilton 

group. The type species differs from L. multitecta 

mainly in the scarcity and small size of its acanthopores, the straightness of its zooecial walls, the smaller 

neanic diameter, and smaller axial ratio for equivalent 

growth stages.

TWGS: Figured specimens USNM 26588, 133888.

Leptotrypella (Leptotrypella) mesostena Boardman, n. sp. 

Plate 6, figures 1-8

Diagnosis, Polytypic species of small ramose zoaria 

(maximum observed diameter of branches 6.8 mm) 

characterized by a constriction of zooecial diameters 

and generally 3 to 4 diaphragms in the early ephebic 

zone just proximal to the distinctively sharp zooecial 

bends; zone of curved laminae narrow for genus, many 

zooecia integrate as a result.

Remarks. Two chronological subspecies are recognized within L. mesostena, L. mesostena mesostena 

from the Centerfield limestone member and L. mesostena provecta from the overlying Ledyard member.

The qualitative and quantitative morphologic differences between the subspecies are in part overlapping. 

These transistional morphologic differences continued 

to develop (see p. 56) and appear more pronounced 

in a still younger form that also contains new characteristics, L. multitecta (p. 57) of the Wanakah 

shale member. This sequence of three forms connected 

by morphologic trends is interpreted as a phylogenetic 

lineage (seep. 52).

L. mesostena can be distinguished from other species 

of Leptotrypella in the Traverse group of Michigan 

and in the Hamilton group by the character of the 

early ephebic zone and the sharp zooecial bends.

Type: Holotype USNM 133878 from USGS collection 

3503-SD.

Occurrence: Centerfield limestone member and Ledyard 

member (of Cooper, 1930) of the Ludlowville shale from the 

Batavia quadrangle to Cayuga Lake. (For complete listing 

of collection numbers see p. 56, 57).

Leptotrypella (Leptotrypella) mesostena mesostena Boardman, 

n. subsp.

Plate 6, figures 1-6

Diagnosis, Small ramose subspecies distinguished 

by crenulate to undulating zooecial walls in the neanic 

region, narrow zone of curved laminae, correspondingly thick zooecial lining, consistently smaller axial 

ratios (0.41:1 to 0.70:1) for corresponding growth 

stages (7 and 2 diaphragms respectively) than related 

forms higher in the Hamilton group, integrate to narrowly amalgamate appearance in tangential sections.

Description. Zoaria of the nominate subspecies are 

small and ramose. Overgrowth is patchy and rarely 

more than one layer is present. Monticules are low 

and consist of megazooecia with irregular cross sections 

and slightly thickened walls, a few irregularly distributed mesopores, and enlarged acanthopores.

In the neanic regions, the zooecial walls are irregularly undulating to crenulate.

In the early ephebic zone proximal to the zooecial 

bend, zooecia are nearly parallel to the surface of the 

branch and are constricted in- diameter. Also, zooecia 

of more advanced growth stages generally contain 3 

to 4 diaphragms proximal to the zooecial bend. The 

zooecial bend is abrupt and well defined. Zooecial 

walls display generally thick linings. The zone of 

curved laminae is narrow. Mural spines are common 

to rare and are concentrated near the zooecial bend. 

Cysts are rare. Diaphragms are simple, generally 

thin, regularly spaced and planar to slightly curved. 

Thin cystoidal diaphragms and thick planar diaphragms are fairly common. A rare thick diaphragm 

is curved to form a cystoidal diaphragm.
56 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

In tangential view, zooecia range from integrate to 

narrowly amalgamate because of the narrowness of 

the zone of curved laminae. Mesopores are fairly 

common outside the monticules. Diaphragms in the 

mesopores are nearer the apertures than those of 

ordinary zooecia. Acanthopores are abundant; they 

inflect the zooecial walls and are not confined to the 

corners of the zooecia.

The following table is based on 27 fragments from 23 

zoaria. Sections from 48 zoaria of L. mesostena 

mesostena were examined.

Minimum Maximum

Diameter of zoarium. __________--___mm_- 3. 0

Width of neanic zone_-__--_-_------do___- 1. 5

Zooecia in 2 mm.________________________ 6

Average diameter of zooecia per fragment

mm__ . 17

Maximum diameter of megazooecia per fragment_._.__..- -__---_-___---_--mm_- . 29 

Acanthopores per zooecium________-___--_ .48

Mesopores per zooecium__________________ .18

Diaphragms proximal to zooecial bend______ 2

6.3 

3. 7

. 26

.41

1. 1

.48

5

Ontogeny

Average number of diaphragms

Width of

ephebic zone

(mm)

1. 0-1. 3 

1. 2-1. 7

1. 7-1. 9

2. 2-2. 7 

6---_------------------------------ 2.4-2. 6

7_--__..---.- ...- ------- 3. 3

Axial ratio 

. 70-. 64 

. 69-. 50 

. 63-. 50 

. 56-. 50 

. 59- 54 

. 41

Types: Holotype USNM 133878 from USGS collection 

3503-SD; figured para types USNM 133876, 133877, 133879-133- 

881.

Occurrence: Centerfleld limestone member of the Ludlowville shale, USGS-SD 3503, 3571, 3593. Localities range from 

the Batavia quadrangle to Cayuga Lake.

Leptotrypella (Leptotrypella) mesostena provecta Boardman, n.

subsp.

Plate 6, figures 7, 8

Diagnosis. Ramose subspecies differentiated from 

the nominate subspecies by lack of fine crenulations 

in zooecial walls of neanic zones, slightly wider zones 

of curved laminae, few thick and cystoidal diaphragms, and fewer integrate zooecia.

Description. Zoaria are small and ramose. In the 

neanic region the zooecial walls are irregularly undulated and are not finely crenulated.

In the ephebic region the zones of curved laminae 

are generally intermediate in width between those of 

L. mesostena mesostena and L. multitecta. The zooecial linings are uniformly thick. Mural spines are 

common, and cysts were not observed. Diaphragms 

are simple, generally thin and planar. Thin cystoidal 

diaphragms and thick planar diaphragms are rare.

In tangential view, zooecia are generally amalgamate to narrowly amalgamate and are rarely integrate. 

Mural lacunae are present but probably are not common.

The following table is based on the 4 available fragments, presumably from 4 zoaria, of L. mesostena 

provecta.

Minimum Maximum

Diameter of zoarium______-_---_-_-_mm__

Width of neanic zone... ____________do____

Zooecia in 2 mm.________________________

Average diameter of zooecia per fragment.__-----_ ___--___--_--____mm__ 

Acanthorpores per zooecium.______________

Mesopores per zooecium__________________

4. 7 

3. 1

6/2

17

42

18

2-3. 

4-5.

Ontogeny

Number of diaphragms

Width of

ephebic zone

(mm)

1. 2

1. 9-2. 4

3.3

6. 8 

4. 4 

8

. 26 

1.2 

. 35

Axial ratin

. 74

. 62-. 65

. 49

Remarks. This subspecies occurs in the Ledyard 

member of the Ludlowville, stratigraphically between 

the occurrences of L. mesostena mesostena in the Centerfield limestone member and L. multitecta in the 

Wanakah shale and King Ferry members. The subspecies is also morphologically intermediate between 

the two forms but resembles L. mesostena mesostena 

more closely in qualitative characteristics.

Qualitative morphologic differences that separate 

the two subspecies of L. mesostena from L. multitecta 

occur in the early ephebic zones just proximal to the 

zooecial bends. The zooecia of the early ephebic zones 

of L. mesostena are constricted in diameter, generally 

contain three or four thin planar diaphragms and are 

nearly parallel to the length of the zoarial branch. 

The zooecia in the early ephebic zones of L. multitecta 

are not constricted, generally have 2 or 3 diaphragms, 

commonly display irregular wall fluctuations and are 

more nearly at right angles to the length of the zoarial 

branches. The zooecial bends in L. multitecta are also 

less abrupt and not as well defined as those of L. 

mesostena.

Qualitative characteristics that display a more 

gradual change in the L. mesostena-multitecta lineage 

and are about intermediate in L. mesostena provecta 

include the widening zones of curved laminae and the 

more amalgamate appearance of zooecial walls in 

tangential sections.

Quantitatively, the diameters of the neanic zones 

are generally smallest in the nominate subspecies of 

L. mesostena, intermediate in L. mesostena provecta 

and largest in L. multitecta (p. 53). Incorporating 

neanic zone measurements into axial ratios, the pro-
SYSTEMATIC DESCRIPTIONS 57

gressive and overlapping change is shown in figure 24. 

Thus, for similar growth stages as determined by the 

number of diaphragms, corresponding values of axial 

ratios become generally higher upward in the proposed phylogenetic lineage.

Types: Holotype USNM 133883 from USGS collection 

3541-SD; figured paratype USNM 133882.

Occurrence: Ledyard member (of Cooper, 1930) of the 

Ludlovvville shale, USGS 3541-SD, from White Creek, Batavia 

quadrangle.

Leptotrypella (Leptotrypella) multitecta Boardman, n. sp. 

Plate 7, figs. 1-4; plate 8, figs. 3-8

Diagnosis. Zoaria ramose, incrusting, or both; 

overgrowth exceptionally well developed; in neanic 

region and ephebic region zooecial walls irregularly 

undulated; 2-3 diaphragms typical in early ephebic 

zone just proximal to the flattened and poorly denned 

zooecial bend; in ephebic region, zone of curved 

laminae characteristically wide; in tangential view, 

walls normally amalgamate, a few scattered zooecia 

integrate; mesopores unusually common for the genus.

Description. Zoaria are ramose, incrusting, or a 

combination of the two habits. Overgrowth is characteristically well developed on ramose zoaria, 2 or 3 

layers commonly occur on older branches.,. As a result, 

few zooids developed fully because their growth was 

halted by the encroaching overgrowth. The ramose 

colonies were extended distally by these overgrowths 

building one upon the other. An overgrowth apparently grew from its point of origin in both a proximal 

and distal direction relative to the supporting colony. 

Proximally, the overgrowth incrusted the supporting 

colony. Distally beyond the tips of the supporting 

colony, the overgrowth assumed a ramose habit, thereby adding length to the complex structure (pi. 7, fig. 

4a). These overgrowths commonly result in irregularities such as knobby growths, right-angle bends in 

branches, or bifurcation of branches at unusual angles. 

Another growth habit within the species is demonstrated by zoaria that form incrustations that can give 

rise to branches (pi. 7, fig. 3). Incrusting zoaria are 

fairly common and display extremely variable zooecial 

characteristics (pi. 8, figs. 3, 7, 8).

Monticules are variable in height. They are composed of several megazooecia that may have thickened 

walls, a few mesopores in varying abundance, and 

enlarged acanthopores.

In the neanic region, zooecial walls display irregular 

undulations, but no consistent development of finer 

crenulations. The neanic regions are commonly interrupted by partial destruction of abandoned growing

tips by either resorption or erosion. These older surfaces are covered by an overgrowth.

In the ephebic zone, irregular undulations are common in the walls of the zooecia so that parts of many 

zooecia are thrown slightly out of the plane of the 

longitudinal sections. Proximal to the zooecial bend 

are 2 or 3, very rarely four diaphragms. The zooecial 

bend is typically flattened and poorly defined. Zooecial linings are of variable thickness and some are not 

easily discernible from the generally wide zone of 

curved laminae. Diaphragms are simple, generally 

thin and planar. Thin cystoidal diaphragms and 

thick planar diaphragms are rare to fairly common. 

Few thick diaphragms are curved enough to become 

cystoidal. Mural spines are typically abundant but 

are rare in a few zoaria. If abundant, they commonly 

are concentrated near the zooecial bend. Incrusting 

zoaria generally display concentrations of mural 

spines near the proximal ends of the zooecia.

In tangential view, the walls generally appear amalgamate. An integrate appearance occurs in a few 

scattered zooecia throughout a zoarium and is more 

common in the thickened walls of monticular zooecia. 

A few zoaria display mural lacunae irregularly distributed in the zooecial walls. Mesopores outside the 

monticules are unusually abundant for the genus and 

are evenly distributed throughout a zoarium. Diaphragms of the mesopores are closer to the apertures 

than those of normal zooecia. Acanthopores are normally abundant, inflect the zooecial walls, and are not 

concentrated at the corners of the zooecia.

The following table is based on 92 fragments from 

48 zoaria. Sections from over 100 zoaria of L. multitecta were examined.

Minimum Maximum

2.6 12.3

1.8 8.0

Diameter of zoarium.----------- ---.mm.

Width of neanic zone- -------------do.--

Zooecia in 2 mm_ ________________________ 5J>£ 7^

Average diameter of zooecia per fragment __ _...--------------------mm-- .20 .28

Maximum diameter of megazooecia per

fragment---------------------__-mm_- .35 .54

Acanthopores per zooecium. ___.___-_____-- .3 1.5

Mesopores per zooecium. __._.__________.- .2 1.0

Ontogeny

Average number of diaphragms

8.. 

10.

Width of

ephebic zone

(mm)

. . 6-1. 4 

1. 0-1. 8

1. 7-2. 8

2. 5-3. 9

3.9

5.8

Axial ratio 

. 73-. 85 

. 62-. 86 

. 58-. 76 

. 55-. 64 

. 56 

. 53

Remarks. L. multitecta differs from L. devonica 

(Duncan) (1939, p. 259, pi. 14, figs. 9, 10) in having
58 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

monticules, more mesopores, and a larger axial ratio 

for corresponding growth stages. The holotype slide 

of L. devonica has 6-7 diaphragms in the zooecia and 

an axial ratio of 0.43 :1. L. multitecta differs from L, 

magninodosa Duncan (1939, p. 226, pi. 9, figs. 8-9) in 

having larger zooecia, smaller acanthopores, and larger 

axial ratios for corresponding growth stages. The 

holotype slide of L. magninodosa contains 6-8 diaphragms and has an axial ratio of 0.39:1.

L. multitecta differs from the holotype slide of L. 

aequabilis Duncan (1939, p. 224, pi. 9, figs. 6, 7) mainly 

in a larger axial ratio for a similar number of diaphragms. The holotype section of L. aequabilis displays 8-9 diaphragms, neanic diameter of 2.3 mm, 

ephebic width of 4.1 mm, and an axial ratio of 0.36:1. 

Qualitatively, the two species are comparable. (For 

further discussion see p. 53).

Types: Holotype USNM 133887 from USGS collection 

3524-SD; figured paratypes USNM 133884-133886, 133889-133- 

892.

Occurrence: Ludlowville shale: Wanakah shale member 

as used by Buehler and Tesmer (in press), USGS-SD 3502 

(USNM collection 1017), 3505, 3511, 3512, 3514, 3515, 3516, 

3519, 3524, 3526, 3532, 3565; King Ferry shale member of 

Cooper (1930) USGS-SD 3564, 3572. Localities range from 

Lake Erie to Cayuga Lake.

Leptotrypella (Leptotrypella) asteriea Boardman, n. sp. 

Plate 9, figure 1; plate 10, figures 1-6

1877. Chaetetes fruticosus Hall (Part) New York State Geol. 

Survey, Paleontology, pi. 38, figs. 1, 5.

Diagnosis. Species extremely variable; zoaria large 

and ramose (maximum branch diameter 25 mm) ; in 

addition to normal monticules, prominences formed 

by distally extended zooecial walls common, appear 

star-shaped in tangential sections. In ephebic zone: 

zooecial walls variable in thickness; thin-walled zooecia 

show irregular thickening and undulations, thin to 

discontinuous zooecial linings, rare mural spines, and 

thin irregularly spaced diaphragms; thick-walled 

zooecia less irregular, with fewer undulations in the 

walls, thicker more continuous zooecial linings, more 

abundant mural spines, and more regularly spaced 

diaphragms.

Description. Zoaria are large and ramose, the most 

complete zoarium of the collection is 45 cm in height. 

Overgrowth is common and gives rise to secondary 

branches as well as the usual incrustations. Abundant 

overgrowth on a zoarium produces irregular to anastomosing branching, although the species basically has 

a simple, dichotomously branching habit. Bulbous 

to elongate swellings on older, proximal parts of zoaria 

appear to be stunted branches (pi. 10, fig. 2). Monticules are abundant and generally low; they contain 

megazooecia with slightly thickened walls, few irregularly clustered mesopores, and enlarged acanthopores. 

In addition to these normal monticules there are 

prominences of comparable size composed of the distal 

ends of zooecia that are elongated toward the centers 

of the prominences in a radial pattern. In tangential 

view, the internal structure of the prominences resembles many-pointed stars. The voids in the prominences 

are partly filled with dark granular material.

In the neanic region, the zooecial walls are generally 

undeviating without crenulatipns or undulations. In 

the ephebic zone, the zooecial walls yary in thickness 

among zoaria or among zooecia in a single zoarium. 

The walls of individual zooecia display irregular 

thickening and undulations, both more pronounced 

where the walls are relatively thin. Also, in the thinwalled zooecia the lining is wanting or is thin and 

discontinuous, and mural spines are very rare. In the 

thick-walled zooecia, the lining is relatively thick and 

mural spines are more common. Where common, spines 

are generally concentrated just distal to the zooecial 

bend. All degrees of transition between extremes of 

wall thickness, undulations and abundance of mural 

spines can be seen within any one of a very few zoaria. 

Most zoaria are more regular but a number of zoaria together display the full range of morphologic variation. 

In longitudinal sections, the boundaries of many 

zooecia range from well-defined lines to serrated zones. 

In other zooecia the boundaries are poorly defined, 

the laminae from adjacent zooecia merging with little 

apparent break. The zone of curved laminae is generally wide. All diaphragms are thin and planar to 

slightly curved. In zooecia with thin walls the diaphragms r.re widely and irregularly spaced. In zooecia 

with thicker walls, the diaphragms are more regularly 

and closely spaced. Cystlike bodies occur in the ephebic zones in varying numbers, singly or in clusters. 

If abundant in a zoarium, they occur either throughout the ephebic zone at all levels in the zoarium or 

unevenly concentrated in parts of the zoarium. The 

cysts have laminated walls continuous with laminae 

of the diaphragms or zooecial walls, and commonly 

inclose dark granular deposits.

In tangential view, apertures are subpolygonal to 

subcircular. The zooecial walls are amalgamate, less 

commonly integrate. Acanthopores are common, inflect the walls to some extent, and ordinarily occur at 

the corners of the zooecia. Mesopores are rare except 

in the monticules.

The following table is based on 65 fragments from 

15 zoaria. Sections from 46 zoaria of L. asteriea were 

examined.
SYSTEMATIC DESCRIPTIONS 59

Diameter of zoarium______- ________ _mm__

Width of neanic zone_____---_____--do----

Zooecia in 2 mm__...______._. ___________

Average diameter of zooecia per fragMaximum diameter of megazooecia per

Acanthopores per zooecium 

Diaphragm ratio___._-___-

Minimum 

8. 8 

5. 1 

6

. 20

. 29 

.25 

. 3

Ontogeny

I-3... 

4-5._.

6-7._.

7-9_ _. 

9-12..

II-15.

Number of diaphragms

Width of

ephebic zone

(mm)

. 8-1.9

2. 0-3. 5

3. 0-3. 8

3. 4-4. 9

4. 1-6. 5

5. 2-6. 7

Maximum 

24 

17.0

Axial ratio

. 81-. 92 

. 70-. 84 

. 69-. 80 

. 68-. 76 

. 56-. 69 

. 53-. 72

Remarks. Hall (1877, pi. 38, figs. 1-5) erected 

Chaetetes fruticosus, figuring three unsectioned syntypes and giving no written description. Thin sections 

show that one of the syntypes (Hall, 1877, pi. 38, fig. 

2) belongs to the genus AtactotoecTius and this specimen is designated as the lectotype of Atactotoechus 

fruticoms (Hall) (p. 76). The remaining two syntypes (NYSM 6181, Hall, 1877, pi. 38, fig. 1 from Canandaigua Lake; NYSM 6183, Hall, 1877 pi. 38, fig. 5, 

from Western New York) belong to L. (Leptotrypella) asterica and are considered only as identified 

specimens of that species. (For further discussion 

seep. 60).

L. asterica is readily differentiated from the species 

of Leptotrypella from the Traverse group of Michigan and from L. mesostena and L. multitecta by its 

large zoaria and the presence of the star-shaped 

prominences.

Types: Holotype USNM 133893 from USGS collection 

3543-SD; figured paratypes USNM 133894-133898.

Occurrence: Ludlowville shale: Wanakah shale member 

as used by Buehler and Tesmer (in press), USNM collection 

1017; King Ferry shale member of Cooper (1930), USGS 

3572-SD. Moscow shale: Portland Point member of Cooper 

(1930). USGS 3551-SD; Kashong member of Cooper (1930), 

USGS-SD 3500" (USNM collection (39) ) 3501, 3528a (USNM 

collection 277A) 3542, 3543, 3552, 3558.

Although L. asterica first appears in the Ludlowville shale, it is very rare there. The species is extremely abundant in the Kashong member from the 

Attica quadrangle to Seneca Lake and is not known 

in the Windom member above.

Leptotrypella (Leptotrypella) furcata (Hall)

Plate 11, figures 1-6

1877. Chdctetcs fnrcatiitt Hall (part), New York State Geol. 

Survey, Paleontology, pi. 37, figs. 1-4, pi. 38, fig. 7.

1939. Atactotoeohus furcatus (Hall) Duncan, Univ. Michigan, Mus. Paleontology, Contr., vol. 5, p. 190.

Diagnosis. Zoaria large, ramose (branch diameters 

6.5 to 16.5 mm) incrusting, or a combination of the 

two habits; monticular mesopores few and irregularly 

distributed, to abundant and clustered at center of 

monticule, surrounded by a ring of megazooecia; in 

neanic zone, zooecial walls irregularly undulating to 

crenulate; in ephebic zone, zooecial walls thick (maximum 0.18 mm), consisting almost entirely of a zone 

of curved laminae with no distinct zooecial lining; 

zooecial walls broadly amalgamate.

Description. Zoaria are both ramose and incrusting; and a combination of the two habits occurs in 

individual zoaria. Overgrowths are common and 

many are thick, contributing appreciably to the total 

diameter of the branches. Within the ephebic region, 

zones in which the tubes are thin walled commonly alternate with normal zones of thick-walled growth. In 

these alternations the zooecia are continuous, not interrupted by basal laminae at sharp breaks in wall thickness. Monticules are either not elevated or only slightly 

raised above the surrounding zooecia. The monticular 

megazooecia and mesopores have thickened walls. 

Some monticules have few mesopores irregularly scattered among the megazooecia, others display a central 

cluster of mesopores surrounded by megazooecia (pi. 

11, fig. 3b).

In the neanic region, zooecial walls are irregularly 

undulating to crenulate. In the early ephebic zone, 

the walls increase rapidly in thickness. In the ephebic 

zone, zooecial wall thickness is uniform except in a 

very few zoaria in which the walls are relatively thin 

and tend to be irregularly thickened and undulatory. 

Distinct zooecial linings are not observed, but the wall 

structure is leptotrypellid, with straight laminae paralleling the zooecia for some distance before curving 

broadly into the zooecial boundaries to form the 

unusually wide zone of curved laminae. Zooecial 

boundaries are commonly not defined; the laminae 

from adjoining zooecia merge without apparent break. 

Mural spines are never abundant, but a few generally 

occur in a zoarium. Small subspherical cysts attached 

to diaphragms or zooecial walls of the ephebic zones 

occur in most zoaria. Diaphragms are thin, planar, 

and widely and irregularly spaced. In a few zoaria, 

diaphragms are as much as 3 or 4 tube diameters 

apart.

In tangential view, the thicker walled zooecia have 

subcircular apertures. Thinner-walled zooecia have 

subcircular to subpolygonal apertures. Zooecial walls 

are broadly amalgamate, and mural lacunae occur in 

some zoaria. Mesopores are generally rare outside
60 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

monticules. Acanthopores range from small to medium and are not confined to zooecial corners.

The following table is based on 27 fragments from 

21 zoaria. Sections from 47 zoaria of L. furcata were 

examined.

Minimum Maximum

Diameter of zoaria._.____-__--__---_mm__

Width of neanic zone_____---_----_-do__--

Zooecia in 2 mm______--___-_-___________

Average diameter of zooeqia per fragment

mm__

Maximum diameter of megazooecia per 

fragment- ______________________ do ___-

Acanthopores per zooecium________________

Wall thickness.______.______-_----.mm._

6. 6 

4. 2 

5

. 17

. 29 

.40 

.05

Ontogeny

2-3_

3-4_ 

5-6. 

7-9-

Number of diaphragms

15-16.

Width, of

ephebic zone

(mm)

1.4

1. 7-2. 4

2. 5-3. 5

3. 0-4. 6

5. 6

6. 5

16. 5

11. 6

7%

. 24

. 43 

. 90 

. 18

Axial ratio

. 79-. 86

. 72- 81

. 65-. 77

. 57-. 77

. 65

. 52

Remarks. Hall (1877) published illustrations of 

syntypes of Chaetetes furcatus and C. fruticosus with 

no descriptions or designations of holotypes. Apparently, C. fruticosus was differentiated from C. furcatus by the presence of high monticules.

Grabau figured specimens that he identified as C. 

fruticosus (1899, p. 136, fig. 20) and C. furcatus 

(1899, p. 137, fig. 21) reassigning them to the genus 

Monotrypa. His specimens apparently were not 

sectioned so their identity is uncertain. Grabau's material was probably not identified correctly, as most of 

his specimens came from the Ludlowville shale. Only 

1 of the 3 species Hall included in syntypes of C. 

fruticosus and C. furcatus have been found below the 

Moscow shale, and that one, L. asterica, is very rare in 

the Ludlowville shale.

Duncan (1939, p. 190) reassigned both C. fruticosus 

and C. furcatus to Atactotoechus without comment.

Sectioning of Hall's syntypes of C. furcatus revealed that 2 species were fortuitously included under 

the one name, largely because of the misleading external 

homeomorphy common in trepostomes. The syntype 

illustrated in pi. 37, fig. 5 (Hall, 1877) under the name 

C. furcatus does belong to the genus Atactotoechus 

and is now included in A. fruticosus (p. 76) as a 

homeotype. The remainder of the specimens designated by Hall as C. furcatus (NYSM 6184, pi. 37, fig. 

1; NYSM 6185, pi. 37, fig. 2; NYSM 6187, pi. 38, fig. 

7; the specimen in pi. 38, fig. 6 was not available) are 

all the same species of the subgenus L. (Leptotrypella} 

and the name furcata is here retained for that species.

L. (Leptotrypella} furcata is considered to have 

evolved directly from L. (Leptotrypella} asterica (p. 

58). Both species display thin, simple, widely spaced 

diaphragms, cysts, and mural spines. L. furcata differs from L. asterica in developing some crenulations 

in the zooecial walls of the neanic zones, and thicker 

ephebic walls showing wide zones of curved laminae 

and no distinct zooecial linings. Also, L. furcata has 

no star-shaped prominences and generally has more 

mesopores in the monticules.

Types: Lectotype NYSM no. 6187 (Hall, 1877, pi. 38, fig. 

7) Bellona, Yates County, New York; paratypes NYSM no. 

6185 (Hall, 1877, pi. 37, figs. 2, 4) Norton's landing, Cayuga 

Lake, New York and NYSM no. 6184 (Hall, 1877, pi. 37, figs. 

1, 3) Norton's Landing, Cayuga Lake, New York; figured 

specimens USNM 133899-133903.

Occurrence: Windom member of the Moscow shale, collection (52) and USGS-SD 3548, 3553, 3559, 3562, 3567, 3569, 

3570, 3575, 3579. Localities range from the Attica quadrangle 

to Owasco Lake. USGS 3559-SD constitutes topotype material 

from the Windom member in the Kashong Creek section at 

Bellona, N.Y.

Leptotrypella (Leptotrypella) amplectens (Grabau) 

Plate 12, figures 1-5

1899. Monotrypa amplectens Grabau, Buffalo Soc. Nat. Sci

Bull., v. 6, p. 137, fig. 22. 

1913. Monticulipora? marylandensis Ulrich and Bassler,

Maryland Geol. Survey, p. 123, pi. 7, figs. 10-12.

Diagnosis. Zoaria incrusting or incrusting and 

subramose, each zoarium intergrown with an auloporoid coral and incrusting a spiriferoid brachiopod; 

in monticules, megazooecial walls strongly thickened, 

acanthopores enlarged; alternating zones of thin and 

thick-walled growth in region generally only ephebic; 

mural spines few to common.

Description. Grabau's description of the external 

appearance and the constant incrusting relationship of 

the species is excellent. All 38 specimens of L. amplectens identified by means of sections are intergrown 

with an auloporoid coral, and the bryozoan and the 

coral together incrust a spiriferoid brachiopod. Calices 

of the coral are generally concordant with the zoarial 

surface indicating equal growth rates of the two organisms. The coral is a species of Aulocystis Schluter 

[=Ceratopora~\ originally identified by Grabau as 

Aulopora tubaeformis Goldfuss, and the brachiopod 

is Spinocyrtia granulosa (Conrad). The incrusting 

growth always occurs on the brachial valve of the 

brachiopod and is concentrated on the anterior half or 

two-thirds of that valve (pi. 12, fig. 4). In welldeveloped incrusting complexes the bryozoan and coral 

display the maximum thickness and short branches 

(maximum observed length of l1/^ inches) at the extreme anterior end of the brachiopod (pi. 12, fig. 2).
SYSTEMATIC DESCRIPTIONS 61

Each branch consists of a central growth of Aulocystis 

completely covered by the bryozoan except for exposed 

calices.

Monticules are variable in height, probably due in 

part to the irregular surface of attachment of the 

bryozoan. The monticules consist of zooecia and 

megazooecia with strongly thickened walls and much 

enlarged acanthopores that display unusually large 

lumina. Included mesopores are variable in number 

but show little increase in concentration over surrounding intermonticular areas.

Zoaria of L. amplectens are attached to the corallites of Aulocystis by a thin basal lamina produced by 

the bryozoan. The boundary between the neanic and 

ephebic zones is poorly defined because of the generally thin zooecial walls of the ephebic zones. In most 

incrusting trepostomatous Bryozoa, the distal part of 

the zooecium that is normal to the surface of the 

zoarium displays ephebic growth characteristics, even 

though constituting the greater part of the zooecial 

length. In L. amplectens, distal parts of continuous 

zooecial tubes oriented normal to the surface show an 

alternation of apparent neanic and ephebic growth. 

The intermittent ephebic zones are marked by a slight 

thickening of the zooecial walls and closer spacing of 

diaphragms. The possible neanic growth is marked by 

very thin walls and more widely spaced diaphragms. 

Zooecial walls range from undeviating to irregularly 

undulating to tightly crenulated. Zooecial linings are 

scarcely noticeable owing in part to their thinness. 

Mural spines are few to common and cysts are rare. 

Diaphragms are planar to irregularly curved and uniformly thin. Cystoidal diaphragms are rare.

In the tangential view, apertures are polygonal, and 

one or more sides of the apertures may be slightly 

curved. Zooecial walls are narrowly amalgamate to 

integrate, primarily because of their thinness. A few 

zoaria display mural lacunae, especially around the 

calices of the coral where the zooecial walls are generally slightly thicker. Acanthopores are large relative to the zooecial wall thickness and they inflect the 

walls. Mesopores vary in concentration from one 

zoarium to the next but are generally few and evenly 

distributed throughout a zoarium.

The following table is based on 12 fragments from 

12 zoaria. Sections from 38 zoaria of L. amplectens 

were examined.

Minimum Maximum

Zooecia in 2 mm..._._______._.._____.___ 5y2 7 l/2

Average diameter of zooecia per fragment

mm.. .26 .32 

Maximum diameter of megazooecia per

fragment.. _____________________ _mm_. .35 .49

Acanthopores per zooecium.---.----------- .32 .90

Mesopores per zooecium-_________________ Rare . 48

Remarks. Grabau suggested (1899, p. 139) that the 

coral and bryozoan lived together as commensals and 

that the commensals began growth on the Spinocyrtia 

after the brachiopod shells were full grown and had 

rolled over to lie on their pedicle valves.

The constant relationship of the incrusting commensals to the brachial valves of the brachiopod does 

strongly suggest that all three forms lived simultaneously. Further, the concentration of incrusting 

growth on the anterior ends of the brachial valves plus 

the anterior extension of short branches generally 

parallel to the length of the shells suggest that the 

anterior margins of the shells were oriented upward 

toward the surface of the water with the posterior 

beaks down on or in the subtratum. There is no evidence favoring the upward orientation of either the 

pedicle or the dorsal valves, assuming that the living 

position of the brachiopod was not exactly vertical.

Monticulipora ? marylandensis Ulrich and Bassler 

1913, tentatively referred to Anomalotoechus by Duncan (1939, p. 188), is considered a junior synonym of 

L. amplectens both on identical morphologic appearances and the presence in the type sections of parts 

of a corallite and brachiopod similar in appearance 

in thin section to those associated with L. amplectens. 

Unfortunately, the remainder of the type specimen 

is too fragmentary to identify the brachiopod.

Types: Figured specimens USNM 72856, 133904-133907.

Occurrence: Grabau reported the species from the Pleurodictyum zone at Avery's Creek and the Wanakah Cliff, both 

along the shore of Lake Erie, Buffalo, New York; also in the 

calcareous bed, above the Pleurodictyum bed, at Avery's 

Creek. Ulrich and Bassler (1913b, p. 124) reported M.I 

marylandensis from the Romney shale, East bank of Evitt's 

Creek below Wolfe Mill in Maryland. In addition, the species 

occurs in the Wanakah shale member of the Ludlowville shale 

in USNM collection 280 and USGS-SD 3502 (USNM collection 

1017) 3505, 3519, 3565, all from the Buffalo and Depew 

quadrangles.

Leptotrypella (Leptotrypella) magniporta Boardman, n. sp. 

Plate 12, figures 6, 7

Diagnosis. Zoaria incrusting; megazooecia unusually large (maximum diameter 0.6 mm), megazooecial 

walls not thickened; ephebic zooecial walls thin; diaphragms thin, closely spaced, few nonparallel forming 

cystoidal diaphragms.

Description. Zoaria are incrusting and overgrowth 

is common. The species generally incrusts both valves 

of Athyris spiriferoides (Eaton) but also occurs on 

other brachiopods and less commonly on small horn 

corals. Monticules are moderately high and are composed of unusually large megazooecia (maximum
62 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

diameter 0.6 mm). Intermonticular acanthopores may 

be slightly enlarged but wall thicknesses are not increased and mesopores are extremely rare.

The neanic region is short and nearly vertical to 

the incrusting surface. Zooecial walls of the ephebic 

region are only slightly thicker than the walls of the 

neanic region and show little variation in thickness. 

Zooecial walls are commonly undeviating in longitudinal section but develop irregular undulations above 

uneven surfaces of attachment. Because of the thinness of the zooecial walls, zooecial linings are rarely 

seen, nearly the complete thickness of the wall being 

formed by the zone of curved laminae. Zooecial 

boundaries are generally not visible. Diaphragms are 

thin, closely spaced (diaphragm ratio normally less 

than 1) and a few are nonparallel and slightly curved, 

forming cystoidal diaphragms.

In tangential view, the zooecia are unusually large 

and sharply polygonal in cross section. The wall 

structure appears integrate to narrowly amalgamate 

because of the thin walls. Mesopores are very rare 

throughout the zoaria. Acanthopores are extremely 

variable in size and number and occur either between 

or at the zooecial corners.

The following table is based on 8 fragments from 7 

zoaria. Sections from 10 zoaria of L. magniporta 

were examined.

Minimum Maximum 

Diaphragms per mm. ephebic zone__________ 3. 4 5. 4

Zooecia in 2 mm_ ________________________ 5 6 Vfe

Average diameter of zooecia per fragment

mm__ .29 .38 

Maximum diameter of megazooecia per

fragment-_____________-----__-__mni__ .44 .61

Acanthopores per zooecium___-__-____.-__ Rare . 74

Ontogeny

Number of 

diaphragms

3-4 

7-9 

17

Width of

ephebic zone

(mm)

1. 3-2. 0 

3. 3

Remarks. A single specimen was collected at the 

Windom locality and differs from the Wanakah specimens only in having thicker zooecial walls. L. magniporta can be differentiated from L. amplectens by 

the large megazooecia of normal wall thickness, close 

spacing of diaphragms, and the lack of commensal 

relationships characteristic of L. amplectens.

Types: Holotype, USNM 133909 from USGS collection 

3565; figured paratype, 133908.

Occurrence: Ludlowville shale: Wanakah shale member as 

used by Buehler and Tesmer (in press), USGS-SD 3515. 3516, 

3565; Tichenor limestone member, USNM collection 250B. 

Moscow shale: Windom member, USGS 3585-SD. Localities 

range from Lake Erie to Canandaigua Lake.

Subgenus PYCNOBASIS Boardman, n. subgen.

Type species. Leptotrypella (Pycnobasis) amphelicta Boardman, n.sp.

Definition. The subgenus includes those species of 

Leptotrypella Vinassa de Regny 1920, that contain 

compound as well as simple diaphragms. Characteristically, the diaphragms are variable in thickness 

and in different combinations can be closely and 

irregularly spaced, strongly curved, and non-parallel. 

Cystoidal diaphragms are common and are formed by 

thick as well as thin curved diaphragms. Also, the 

zooecial linings of the subgenus are thick and most 

species have a narrow zone of curved laminae resulting in a narrowly amalgamate to integrate appearance 

in tangential sections.

Remarks. The diaphragms of L. (Pycnobasis) approach, in configuration and arrangement, diaphragms 

typical of the atactotoechids (p. 69). The taxonomic 

importance of the nature and arrangement of diaphragms is well demonstrated by their constancy when 

correlated with wall structures in several suprageneric 

groups, such as the stereotoechids and atactotoechids. 

It is, therefore, of interest and importance to find 

forms with a distinctly leptotrypellid wall developing 

diaphragms of atactotoechid aspect.

Wall structure is presently considered to be the most 

definitive of the family characters and the subgenus 

has strongly leptotrypellid walls, thus suggesting 

affinities with Leptotrypella. In addition to wall 

structure, the acanthopores of L. (Pycnobasis) are 

typical of Leptotrypella rather than the distinctly 

different acanthopores of the atactotoechids.

If the New York forms are adequate to demonstrate 

the origin of the subgenus, the development of diaphragms of atactotoechid appearance is gradual and 

a matter of degree, with the exception of the sudden 

appearance of compound diaphragms. Thus, an independent and parallel evolutionary development of 

atactotoechid-like diaphragms in Leptotrypella is indicated. No known phylogenetic connection is developed 

between the subgenus and the atactotoechids of the 

Hamilton group in New York.

Another character typical of L. (Pycnobasis) that 

would seem to indicate possible atactotoechid affinities 

is the integrate appearance of some of the forms in 

tangential sections. However, integrate appearance 

can be manifested in two fundamentally different types 

of wall structure (p. 30). In L. Pycnobasis), integrate appearance is the result of a narrow but distinct 

zone of curved laminae. In the atactotoechids it is the 

result of laminae that remain straight up to their ends 

at the zooecial boundaries. Thus, an integrate appear-
SYSTEMATIC DESCRIPTIONS 63

ance by itself is not considered to be of family importance in determining the affinities of L. (Pycnobasis.}

Specimens belonging to the subgenus are geographically restricted in occurrence to the 40 mile long strike 

distance between Canandaigua and Cayuga Lakes (fig. 

4). The field collecting was done in enough detail 

throughout the area between Buffalo and Cayuga Lake 

to suggest that this geographic distribution is not fortuitous. The relatively small geographic range may be 

the result of close environmental control, as the shale 

and mudstone farther west become more silty in the 

eastern area of occurrence (p. 15). In keeping with 

the inferred phylogenetic relationships, the Canandaigua-Cayuga Lake region is postulated to be at least 

part of the region in which the subspecies evolved from 

the more conservative lineages of L. (Leptotrypella}.

Zoaria of L. (Pycnobasis} available for study are 

few; three of the four species named here are represented by one to three zoaria. Under most circumstances the naming of new species based on so few 

specimens is merely guesswork and considered poor 

practice. However, the genus Leptotrypella is the 

most abundantly represented trepostone genus in the 

Hamilton group of New York and most of the species 

are known from more than adequate numbers of zoaria. 

Study of these large numbers of zoaria indicate the 

approximate amount of variation that can be expected for the characters considered to be of specific 

value and also demonstrates morphologic gaps between 

the well known species and the poorly known species 

of L. (Pycnobasis). Because of this generally good 

understanding of the genus, and the phylogenetic importance that is indicated by the poorly known species 

of L. (Pycnobasis), L. pacJiyphragma, L. tuberata, 

and L. polita are described on material generally considered to be inadequate in numbers of specimens.

Inferred phylogeny of L. (Pycnobasis). L. (Leptotrypella} mesostena mesostena (p. 55) is considered to be a subspecies close to the point of phylogenetic divergence of L. (Pycnobasis) from L. (Leptotrypella). The subspecies displays some characteristics of both subgenera of Leptotrypella and probably was ancestral to L. (Pycnobasis) amphelicta (fig. 

23) us well as L. multitecta (p. 57). The diaphragms 

of L. mesostena mesotena are intermediate between 

those of the subgenera. The subspecies displays diaphragms that are thin, regularly spaced, and planar 

to slightly curved, typical of L. (Leptotrypella), and 

many diaphragms that are cystoidal or thick, more 

typical of L. (Pycnobasis}. The cystoidal diaphragms 

of L. 'mesostena mesostena generally are thin and occur in several species of L. (Leptotrypella}. A few

thick cystoidal diaphragms occur in L. mesostena 

mesostena, however, and these are fairly common in 

L. (Pycnobasis} and are very rare in L. (Leptotrypella}. No compound diaphragms were observed in 

L. mesostena mesostena, however, so the species is 

placed in L. (Leptotrypella}. Other characters of the 

subspecies considered intermediate or more typical of 

L. (Pycnobasis) include thick zooecial linings, narrow zones of curved laminae, and a resulting integrate 

to narrowly amalgamate appearance in tangential sections.

A phylogenetic connection between the subgenera 

seems most likely between L. mesostena mesostena and 

L. (Pycnobasis) amphelicta (fig. 23). Morphologic 

similarities between the two taxa include the nature 

of the diaphragms discussed in the preceding paragraph plus crenulated neanic zones that are found in 

both forms. Morphologic changes observed from the 

subspecies to L. amphelicta include the development 

of compound diaphragms, more common thick cystoidal diaphragms, slightly wider zones of curved 

laminae, higher monticules, larger neanic diameters, 

higher axial ratios for any one growth stage, less 

abrupt zooecial bends, and a generally more amalgamate appearance.

The remainder of the species of L. (Pycnobasis} are 

not well enough known to attempt to arrange them 

phylogenetically. The few zoaria available do show 

a progressive change from amalgamate to narrowly 

amalgamate to integrate appearances in tangential sections if arranged stratigraphically. Also, the diaphragms become strongly atactotoechid in appearance; 

L. tuberata displays monticular diaphragms similar to 

the diaphragms of the genus Loxophragma (p. 78) 

and L. polita contains diaphragms characteristic of 

Atactotoechus (p. 69).

Leptotrypella (Pycnobasis) amphelicta Boardman, n. sp. 

Plate 13, figures 14

Diagnosis. Medium-sized ramose species (maximum diameter of branches about 9 mm) with high 

monticules displaying irregular zooecial growth, undulating to strongly crenulate zooecial walls in neanic 

zone, planar to strongly curved diaphragms varying 

in thickness and spacing and commonly cystoidal, and 

moderately wide zones of curved laminae resulting in 

amalgamate intermonticular zooecia.

Description. Zoaria are ramose, and overgrowth is 

rare. Monticules are high and display irregular to 

chaotic zooecial growth in longitudinal view. Megazooecia have strongly thickened walls, and acantho-
64 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

pores may be enlarged. A few mesopores are irregularly clustered near the center of the monticule or scattered between the megazooecia.

In the neanic region, zooecial walls have fine, well 

developed crenulations or irregular, more widely 

spaced undulations that are especially strong near the 

ephebic zone. In the ephebic zone, the walls are generally straight. Undulations of the neanic walls extend into the thickened walls of a few zooecia, however, and these walls commonly have some irregularities in thickness. Zooecial linings are thick and continuous. The zones of curved laminae are wider than 

those of L. mesostena and nearly comparable with 

those of L. multitecta. The zooecial boundary is either 

undistinguishable or a narrow serrated zone of abutting laminae. Mural spines are rare to common and 

do not concentrate in the early ephebic zones of the 

zooecia as is common in several other species of the 

genus. Diaphragms are irregularly spaced, planar to 

strongly curved, and variable in thickness. Thick or 

thin cystoidal diaphragms are common. Thicker diaphragms commonly have compound structure.

In the tangential view, zooecial apertures are subpolygonal to subcircular. The walls are generally 

amalgamate, but a few zooecia appear integrate. Walls 

of megazooecia are integrate to narrowly amalgamate. 

Mural lacunae are common, especially in the monticules. Mesopores are scarce to fairly common. Acanthopores are common but rarely inflect the zooecial 

walls. Specimens sectioned in the original matrix 

show acanthopores extending as much as 1.5 mm beyond the zooecial apertures. The parts of the acanthopores that extend beyond the zoaria are slightly 

curved and taper gradually to a rounded point.

The following table is based on 11 fragments from 

6 zoaria. Sections from 12 zoaria of L. amphelicta 

were examined.

Diameter of zoarium____________.___mm_-

Width of neanic zone_____-_-_--_-__do_--_

Zooecia in 2 mm_______-_________________

Average diameter of zooecia per fragment

mm._ 

Maximum diameter of megazooecia per

Minimum Maximum 

8. 8 

6.5 

6

Acanthopores per zooecium_ 

Mesopores per zooecium. __

4. 9 

3. 3

5*/2

. 20

. 30 

.50 

.11

Ontogeny

2-3-

3-5. 

5-6-

Number of diaphragms

Width of

ephebic zone

(mm)

1. 4-1. 6

1. 7-2. 3

3. 3

26

38

72

36

Axial ratio

. 67-. 71

. 68-. 74

. 58

Remarks. L. amphelicta differs from L. mesostena 

mesostena in developing more strongly curved and irregularly spaced diaphragms that are commonly compound. Cystoidal diaphragms are generally thicker 

and compound in L. amphelicta. In addition, in L. 

amphelicta the zones of curved laminae are wider, 

monticules are higher, neanic diameters are larger, 

axial ratios are higher for corresponding growth 

stages, and the zooecial bends are less abrupt and well 

defined than in L. mesostena mesostena.

L. amphelicta differs from L. (Leptotrypella} multitecta mainly in the crenulate zooecial walls of the 

neanic zones, thicker zooecial linings, high monticules, 

and the nature of the diaphragms.

The unusual distal extension of acanthopores beyond 

the zoarium may be more common within the genus 

than is apparent. In addition to those acanthopores 

protected by matrix in available specimens of L. 

amphelicta, a few acanthopores extend well into protecting overgrowths in free specimens of most species. 

Since most of the Hamilton material is free of surrounding matrix, those long acanthopores are normally 

broken, leaving no indication of their length beyond 

the surface of the zoarium.

Types: Holotype USNM 133910 from USGS collection 

3558a-SD; figured para types USNM 133911, 133912, 133992.

Occurrence: Ludlowville shale: Wanakah shale member as 

used by Buehler and Tesmer (in press), USGS 3558a-SD; 

Tichenor limestone member, USGS 3586-SD. Moscow shale: 

Kashong member of Cooper (1930), USGS-SD 3552, 3558. 

Localities range from Canandaigua Lake to Seneca Lake.

Leptotrypella (Pycnobasis) pachyphragma Boardman, n. sp. 

Plate 15, figures 3, 4

Diagnosis. Ramose species distinguished by generally thick, planar to slightly curved, regularly 

spaced and parallel diaphragms; zooecial walls thick, 

linings thick, zone of curved laminae thin; resulting 

in narrowly amalgamate, less commonly integrate appearances in tangential view.

Description. Zoaria are ramose and overgrowth is 

common. Monticules are variable in height from 

colony to colony. The diameters of the megazooecia 

are about twice the diameters of the intermonticular 

zooecia and are generally more integrate in tangential 

view. Mesopores are either irregularly scattered or 

centrally clustered in the monticules. The thickness of 

monticular zooecial walls is slightly to greatly increased over the walls of surrounding zooecia.

In the neanic region, the zooecial walls are undeviating to irregularly undulating. In the ephebic zone, 

the zooecial walls are thick, (average 0.1 mm). The 

zone of curved laminae is relatively narrow and generally the zooecial boundary is visible as a serrated
SYSTEMATIC DESCRIPTIONS 65

zone of overlapping and abutting laminae. The 

zooecial lining is thick, contributing more than half of 

the wall thickness. The diaphragms are characteristically thick, causing abrupt increases in wall thickness 

as the diaphragm laminae join the wall. The diaphragms are planar to slightly curved, generally 

parallel to each other, and regularly spaced. Compound diaphragms are fairly numerous and cystoidal 

diaphragms are rare to common. Mural spines are 

variable in concentration and if abundant are concentrated just distal to the zooecial bend. The spines 

are characteristically irregular in shape, many are 

strongly curved and bent, and a few are dichotomously 

branched. Cysts are variable in number, irregularly 

distributed in zoaria, and many are thick walled.

In tangential view, apertures are subpolygonal to 

circular. Zooecial walls are generally narrowly amalgamate, less conmmonly integrate. Mural lacunae are 

abundant in the narrowly amalgamate walls. Acanthopores are small to medium sized, not confined to 

zooecial corners and a few display central canals. 

Mespores are unequally distributed through a zoarium 

and are more closely tabulated than the zooecia.

Remarks. Only two zoaria of this species are available for study. The holotype is from the Tichenor 

limestone member of the Ludlowville shale and seven 

large fragments of the zoarium were sectioned. The 

second zoarium is from the Wanakah shale member of 

the Ludlowville shale and three fragments were sectioned. Despite the inadequate number of zoaria, the 

species is thought to be distinct, based on the nature 

of the diaphragms, and is included because of its possible importance to the phylogeny of the genus.

Minimum Maximum 

Diameter of zoarium._______________mm__ 7. 4 10. 6

Width of neanic zone....___________do___- 4.2 7.0

Zooecia in 2 mm...-_..____.__.__.._.__._ 6 7 l/2

Average diameter of zooecia per fragment

mm._ .18 .27 

Maximum diameter of megazooecia per 

fragment-___--__--._______-__-__mm__ .35 .49

Acanthopores per zooecium.____-__-____-_ .38 .68

Mesopores per zooecium._________________ Rare . 33

Ontogeny of holotype

6-7. 

8-9.

Number of diaphragms

Width of

ephebic zone

(mm)

2. 3-3. 7 

2. 9-4. 2

Axial' ratio

. 53-. 69 

. 57-. 67

Types: Holotype USNM 133918 from USGS collection 

3586-SD; paratype USNM 133919.

Occurrence: Ludlowville shale: Wanakah shale member as 

used by Buehler and Tesmer (in press), USGS 3555-SD; 

Tichenor limestone member, USGS 3586-SD. Both localities 

are on Canandaigua Lake.

Leptotrypella (Fycnobasis) tuberata Boardman, n. sp. 

Plate 14, figures 1, 2

Diagnosis. Species distinguished by subramose 

growth habit; extremely high monticules consisting of 

an irregular growth of centrally grouped mesopores 

surrounded by megazooecia with greatly thickened 

walls, and extremely enlarged acanthopores; many 

compound monticular diaphragms, nonparallel and unevenly and closely spaced; thin and planar intermonticular diaphragms; integrate zooecial walls.

Description. Zoaria are subramose and branches 

are thick (maximum diameter 22 mm) and relatively 

short (complete colony has height of 10.3 cm). Some 

zoaria display overgrowth. Monticules are extremely 

high and are prominent in external views of the zoaria. 

The structures of the monticules commonly display 

irregular to chaotic growth. An irregular grouping 

of mesopores generally occurs near the center of a 

monticule. The mesopores are surrounded by, or distributed irregularly between, megazooecia of moderate 

diameters. The walls of the megazooecia and mesopores generally are greatly thickened and the monticular acanthopores are much enlarged.

In the neanic region the zooecial walls are straight 

to irregularly undulating. In the ephebic zones, the 

zooecial boundary is a well defined irregularly serrated zone of overlapping laminae that meanders back 

and forth within the zone of curved laminae. The 

abutting of the laminae at the zooecial boundaries is 

commonly imperfect, leaving voids that produce mural 

lacunae seen in the tangential sections. The zone of 

curved laminae is relatively narrow. The zooecial 

linings are generally continuous but vary greatly in 

thickness depending upon the thickness of the immediately proximal diaphragms that continue into the 

zooecial linings. The thicker diaphragms form thick 

zooecial linings just distal to the junctions of the 

diaphragms with the zooecial walls. The thicker diaphragms occur in similar positions in neighboring 

zooecia and are generally grouped into zones of several diaphragms that normally are also more closely 

spaced. The zooecial walls are therefore thicker 

within these zones of thicker diaphragms. The intervening thinner walled zones commonly become neanic 

in appearance and may continue for considerable 

distances along the lengths of the zooecia, resulting in 

a zone that appears alternately ephebic and neanic, in 

a generally ephebic region. Most diaphragms are 

simple, thin, planar and perpendicular to the zooecia 

in intermonticular regions. Compound diaphragms 

are rare in zooecia between monticules. In monticules, 

compound diaphragms are fairly common and are
66 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

generally nonparallel, and unevenly and closely 

spaced, as in the genus Loxophragma in the atactotoechid group (p. 78). A few cystoidal diaphragms 

occur throughout a zoarium. Small thick-walled cysts 

are rare and generally are attached to the diaphragms. 

Mural spines are rare.

In the tangential view, zooecial apertures are subpolygonal to subcircular. The zooecial walls are generally integrate, but a few zooecia appear narrowly 

amalgamate. The holotype zoarium rarely has mural 

lacunae but the unfigured paratype displays them 

evenly distributed in monticular and intermonticular 

areas. Mesopores are rare outside the monticules. 

Acanthopores occur both at and between zooecial 

corners and many are on one side or the other of the 

zooecial boundary and strongly inflect the walls.

The following table is based on 8 fragments from 

the 3 available zoaria of L. tuberata.

Diameter of zoarium__-___-^-___mm__ 

Width of neanic zone. ________ .do.

Zooecia in 2 mm__-_---_---_-_------_

Acanthopores per zooecium_ __________

Mesopores per zooecium. _____________

Average diameter of zooecia per fragMinimum Maximum

10. 1 22. 0

7. 5 16. 2

7 7V2

.50 .70

Rare . 11

Maximum diameter of megazooecia per 

fragment. __.___--_____--_ _ _do_

Ontogeny

Number of diaphragms

. 23

. 32

Width of

ephebic zone

(mm)

2.3

2.9-3.9 

6.4

. 26

. 44

Axial ratio 

0.77 

.72-.S2 

.66

Types: Holotype USNM 133914 from USGS collection 

3582-SD ; figured paratype USNM 133915.

Occurrence: Ludlowville shale: King Ferry shale member 

of Cooper (1930), USGS 3582-SD; Deep Bun member of 

Cooper (1930), USGS 3555a-SD. Collections are from Cayuga 

Lake and Canandaigua Lake respectively.

Leptotrypella (Pycnobasis) polita Boardman, n. sp. 

Plate 13, figure 5 ; plate 14, figure 3

Diagnosis. Large ramose species distinguished by 

low monticules containing few mesopores; parallel, 

closely spaced, planar to curved diaphragms, commonly cystoidal and compound ; narrow zone of curved 

laminae resulting in generally integrate zooecial walls.

Description. Zoaria are large and ramose. Overgrowth is common. Monticules are either low or not 

raised above the surrounding zooecia. Megazooecia 

have slightly thickened walls, acanthopores are unchanged to slightly enlarged, and mesopores are rare 

and irregularly distributed in the monticules.

In the neanic region, the zooecial walls typically are 

irregularly undulating to crenulated. In the ephebic

zone, the zooecial boundary is either not visible or an 

irregularly serrated zone of overlapping laminae that 

meanders back and forth within the narrow zone of 

curved laminae. The zooecial linings are generally 

thick and continuous. Diaphragms are typically 

parallel, closely spaced, and planar to slightly curved. 

Thicker diaphragms may be compound and cystoidal 

diaphragms are common. The diaphragms approach 

those of the genus Atactotoechus (p. 69) in their 

general appearance. Mural spines are abundant and 

are generally concentrated just distal to the poorly 

defined zooecial bends or in the proximal regions of 

overgrowth. Cysts are rare and are small and thick 

walled.

In the tangential view, zooecial apertures are subpolygonal to subcircular. The zooecial walls are generally integrate, but a few zooecia appear narrowly 

amalgamate. Mural lacunae are rare and occur only 

in the narrowly amalgamate walls. Acanthopores are 

abundant, are not restricted to the corners of the 

zooecia and generally inflect the zooecial walls. Mesopores are rare.

The following table is based on ten fragments from 

the one available zoarium of L. polita.

Minimum Maximum 

Diameter of zoarium__.___-_____mm-- 7.6 14.4

Width of neanic zone__.____-.do.-__ 5.8 9.6

Zooecia in 2 mm____________.________ 5Vfe §Vz

Average diameter of zooecia per fragment_----_-------_---_---___rnni-- .26 .29

Maximum diameter of megazooecia per

fragment- __-______-__--___ _do_ _ _ _ .41 .48

Acanthopores per zooecium.___--._.__ .50 .73 

Mesopores per zooecium-_____________ Rare . 19

Ontogeny

Width of 

ephebic zone

(mm) Axial ratio

__.._ 1.4-2.1 . 78-. 82

_____ 2.5-2.6 .70

_____ 4.6 .61

_____ 5.2-5.6 .61

18___------- ---_ ._-.--_ -------- 5.5 .55

Remarks. Only one zoarium of this description was 

available for study but it is notable for the remarkable 

similarity of its diaphragms with those of Atactotoechus, a genus with a quite different wall structure and 

at present thought to be in another family group. If 

present evaluations of the taxonomic importance of 

wall structure prove to be sound, the development of 

"atactotoechid" diaphragms in L. polita must have 

been independent and an example of parallel evolution (p. 62).

Type: Holotype USNM 133913 from USGS collection 

3558-SD.

Occurrence: Kashong member of Cooper (1930) of the 

Moscow shale, USGS 3558-SD, Kashong Creek, Seneca Lake.

Number of diaphragms

4-5_

14-17-
SYSTEMATIC DESCRIPTIONS 67

Genus POLYCYLINDRICTTS Boardman, n. gen.

Type species. Polycylindricus asphinctus Boardman, n. sp.

Diagnosis. Dichotomously branching zoaria with 

additional small perpendicular secondary branches; 

zooecia parallel to length of branches and extremely 

long in neanic zone, progressively compressed away 

from the center of the branch, in some species zooecia 

completely constricted and walls coalesce to form a 

thick-walled cylinder separating neanic and ephebic 

zones; zooecia in any one zoarium either long and 

continuous from neanic to ephebic zones or short and 

limited to ephebic zone; ephebic zones narrow with 

few diaphragms; zooecial walls leptotrypellid; acanthopores common, extremely large in diameter, project 

well beyond surfaces of zoaria; mesopores rare.

Description. Zoaria are ramose; the branches are 

cylindrical. In addition to normal dichotomous 

branching, discordantly smaller secondary branches are 

common and make an angle of approximately 90° with 

the supporting branches. Monticules do not occur in 

all species. Externally, the zoaria have a distinctive 

spiny appearance due to large, extended acanthopores.

In the neanic zone, the zooecia are polygonal in cross 

section, extremely long, and parallel to the length of 

the branches. The zooecia become propressively more 

flattened in cross section from the centers of the 

branches outward, also developing curved outer walls 

that parallel the curved outer extremities of the 

branches. If the compression of the zooecia is complete, the walls of the outer zooecia of the neanic zone 

coalesce to form a thickened cylinder separating the 

neanic from the ephebic zones. If the zooecia do not 

collapse completely, the walls remain distinct and it 

is possible to trace individual zooecia from the neanic 

to ephebic zones. A single zooecium, running longitudinally in the neanic zone, remains in the outer row 

of that zone for a considerable distance. Thus, there 

are not as many tubes passing from the neanic zone 

to the ephebic zone as there are zooecia opening at the 

surface in the ephebic zone. To make up for this deficiency, short secondary zooecia arise from the outer 

side of the long primary zooecia in the outer row of 

the neanic zone. No communication is visible between 

the void of the primary tube and that of the secondary 

zooecia. These secondary zooecia show almost no 

neanic growth and develop a normal ephebic zone that 

opens out to the surface of the zoarium at normal 

angles. Finally, the primary zooecium forms an ephebic zone and opens at the surface of the zoarium 

adjacent to the most distal of the secondary zooecia 

attached to the primary zooecium. In tangential sections, primary and secondary zooecia are not distinguishable.

The ephebic zone is characteristically narrow, with 

few diaphragms. Further outward growth is accomplished by an irregular thin-walled or neanic development, attached directly to the initial ephebic zone generally without an intervening basal lamination. This 

second thin-walled region is adjoined by another 

ephebic zone with diaphragms, and a few zoaria develop a second thick-walled cylinder, concentric with 

the smaller initial cylinder (pi. 16, fig. 5). The second 

cycle of growth gives rise to the perpendicular, secondary branches of the zoaria by developing elongated 

neanic zones in restricted areas. The wall structure 

is leptotrypellid (p. 32), the laminae of the ephebic 

walls lie parallel to the lengths of the zooecia for a 

considerable distance to form a zooecial lining. The 

laminae then curve distally out to the zooecial boundary and intersect the boundary at 90°. The large 

acanthopores have their maximum diameters near their 

bases.

In tangential section, the walls are amalgamate. 

Acanthopores are common, extremely large, and 

project well beyond the surface of the zoarium. Mesopores are rare.

Remarks. The short secondary zooecia limited to 

the ephebic zone would be considered mesopores except 

they are not consistently small in diameter and cannot 

be distinguished from primary zooecia in tangential 

sections.

The formation of the cylinder or tube by the union 

of zooecial walls is unique in the Trepostomata and 

the acanthopores of the genus are very unusual in 

longitudinal shape and size. The wall structure appears leptotrypellid, but subsequent work may very 

well place the genus in another suprageneric grouping.

Dekayia devonica Ulrich 1890, is here assigned to 

Polycylindricus. Ulrich described the species based 

on cotypes from two widely separated localities, the 

Falls of the Ohio at Louisville, Kentucky, and 

Eighteen Mile Creek, Buffalo, New York.

The cotypes from the Jeffersonville limestone at the 

Falls of the Ohio consist of several ramose fragments 

plus the fragment that matches the only illustration 

of the Falls of the Ohio material (Ulrich, 1890, pi. 45, 

fig. 5). All the material is silicified and thus cannot 

be profitably sectioned. Fortunately, Polycylindricus 

has a distinctive exterior and the illustrated fragment 

belongs to this genus. Of the remaining specimens, 

only one belongs to Polycylindricus. The other fragments belong to another unidentified genus.

The New York material consists of a single thin o

section plus three ramose fragments labeled as cotypes.
68 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

Ulrich's illustrations (1890, pi. 45, figs. 5a-5d), include 

both the thin section and external views of one of the 

cotypes. The thin section is not adequate to determine the characters of the species, however, it belongs 

to Polycylindricus. The three fragments also belong 

to Polycylindricus. The label accompanying the New 

York specimens cites the Hamilton group of Eighteen 

Mile Creek and the specimens may be from any of the 

members of formations in the Hamilton group of that 

area.

The specimens of Polycylindricus from the Falls of 

the Ohio have definite convex monticules while those 

from New York have none, so they are not considered 

conspecific. Ulrich (1890, description of pi. 45, fig. 

5a), indicates the possibility of two species in describing the New York specimens: "A branching hollow fragment, probably representing another species" 

(that is, other than the specimen shown in figure 5 

from the Falls of the Ohio). The published description of Dekayia devonica therefore includes observations from 3 species belonging to 2 genera.

The Falls of the Ohio specimens are the only ones 

of Polycylindricus known to have convex monticules. 

The name Polycylindricus devonicus (Ulrich) is restricted to this monticulate species and Ulrich's illustrated specimen (1890, pi. 45, fig. 5 USNM 136827), is 

here designated the lectotype of that species.

Polished transverse sections of Ulrich's Eighteen 

Mile Creek cotypes show an inner thickened wall 

separating the neanic and ephebic regions and they are 

placed in Polycylindricus clausus Boardman, n. sp.

Polycylindricus asphinctus Boardman, n. sp. 

Plate 15, figures 1, 2

Diagnosis. Species distinguished by constriction of 

zooecia in outer part of neanic zone without formation 

of thickened cylinder; finely crenulate zooecial walls 

in neanic zone.

Description. Zoaria are small and ramose. Secondary or rejuvenated growth is common and produces discordantly small branches projecting at right 

angles to the main branches. Monticules are not distinguishable.

In the neanic region, the parallel zooecial walls are 

finely and irregularly crenulate. Complete compression of zooecia is uncommon in the outer portions of 

the region and the zooecial walls remain discrete, so 

that a thickened cylinder is not formed. In the early 

part of the ephebic zone, the walls increase in thickness slowly and uniformly. Nearing the apertures, the 

walls thicken abruptly and end in bluntly rounded 

margins that are controlled by the curved laminae in

the walls. The diaphragms are thin and are located 

in the proximal portion of the ephebic zone preceding 

the sharp zooecial bend. No more than two diaphragms were observed in a zooecium. The zooecia 

reach the surface at extremely variable angles. As 

many as six short secondary zooecia arise from a long 

primary zooecium.

In the tangential view, zooecial apertures range from 

subpolygonal, partly subpolygonal and partly circular, to subcircular. Tangential thin sections are 

broadly amalgamate if they pass through the distally 

thickened walls. Acanthopores are well laminated and 

usually large. The larger acanthopcrres are equal in 

diameter to the largest zooecia and project beyond the 

zooecia as much as 0.2 mm. Maximum diameters are 

attained either at the bases of the acanthopores or between the bases and approximately one-fourth of their 

length above the bases. From that maximum point the 

acanthopores decrease slowly in size ending in broadly 

rounded tips. Elongated apertures of zooecia are 

arranged radially around single acanthopores giving 

the group a petaloid appearance.

The following table is based on 8 thin sections from 

7 zoaria. Sections from 11 zoaria of P. asphinctus 

were examined.

Minimum Maximum 

3. 5 4. 8 

2. 8 4. 1 

.5 1.2 

.71 .89 

0 2 

6 7 

Average diameter of zooecia per fragment

mm.. .20 .26 

Zooecial wall thickness.__-__.__- ___do____ ______ .13

Acanthopores per zooecium-_______________ .16 .25

Diameter of acanthopores____._-____mm__ ______ .30

Types: Holotype USNM 133916 from USGS collection 

3524-SD; figured paratype USNM 133917.

Occurrence: Wanakah shale member (as used by Buehler 

and Tesmer, in press) of the Ludlowville shale, USGS-SD 

3515, 3516, 3524, 3545, 3565. Localities range from Lake Erie 

to the Caledonia quadrangle.

Polycylindricus clausus Boardman, n. sp. 

Plate 16, figures 1-6

1890. DeJcayia devonica Ulrich (part), Illinois Geol. Survey, 

v. 8, p. 416, pi. 45, figs. 5a-5d.

Diagnosis. Species distinguished by thick-walled 

longitudinally plicated cylinder formed between 

neanic and ephebic zone by union of walls of compressed zooecia.

Description. Zoaria are small and ramose. Discordantly small branches projecting at right angles to

Diameter of zoarium___________-____mm.

Width of neanic zone.___----_---_ _do_ _.

Width of ephebic zone_____________do__.

Axial ratio.__________-___---__-____-__.

Diaphragms in ephebic zone..____________

Zooecia in 2 mm______-___-_-_---_--_-_.
SYSTEMATIC DESCRIPTIONS 69

the main branches are common. Monticules are not 

distinguishable.

In the neanic region, the parallel zooecial walls are 

smooth or crenulated. The zooecia are completely 

constricted in the outer portions of the neanic regions, 

the individual zooecial walls uniting to form a thick 

longitudinally plicated cylinder. Although the cylinder makes it impossible to follow the individual 

zooecia from the neanic to the ephebic zones, the relationship between primary and secondary zooecia (p. 

67) is thought to be the same as that in P. asphinctus. 

The zooecia in the neanic zone so nearly parallel the 

cylinder that they join the cylinder at a much slower 

rate than the zooecia branch from the cylinder in the 

ephebic zone. Thus, many of the zooecia in the ephebic 

zone are not continuous with the tubes in the neanic 

zone, so must have their origin in the ephebic zone 

as do the secondary zooecia of P. asphinctus. In the 

ephebic zone, the zooecial walls are usually thickened 

upon leaving the cylinders and increase gradually to 

a maximum near the aperture. The distal ends of the 

walls are broadly rounded. Normally, the zooecial 

walls are almost perpendicular to the cylinder throughout the ephebic zone. Rarely, zooecia separated from 

the cylinder wall proximal to the zooecial bend and 

developed 1 or 2 thin diaphragms.

In the tangential view, the zooecial boundaries and 

apertures are irregularly subpolygonal to subcircular, 

and vary from triangular to many sided and from 

elongated to equidimensional. The apertures also show 

an unusual range in size. Elongated zooecia are arranged radially around single acanthopores giving the 

grouping a petaloid appearance. The Avails are amalgamate. Acanthopores are common and well laminated. From their .broad bases, the acanthopores 

gradually decrease in diameter and end in broadly 

rounded tips. Mesopores are rare and difficult to 

distinguish in tangential sections due to the great 

variance in zooecial diameters.

The following table is based on 21 thin sections 

from 20 zoaria. Sections from more than 50 zoaria 

of P. clausus were examined.

Minimum Maximum

Diameter of zourium._______________mm._

Width of neanic zone._____________do_

Width of ephebic zone_____-_--_---do--_-

Axial ratio._____________________________

Diaphragms in ephebic zone_______________

Cylinder thickness._.._-.----.--_-_ _mm_ _

Zooecia in 2 mrn_________________________

Zooecial wall thickness_-_-_-----.-__inm__

A.canthopores per zooecium.______________

Diameter of acanthopores-__---___._mm._

1. 9 

1. 2

.5

.59

4. 8 

4. 2 

1. 4 

.88 

2

. 13 

8

.10 

.28 

.25

Types: Holotype USNM 133920 from USGS collection 

3553-SD; figured panxtypes USNM 133921-133925.

. 03

.03 

.10

Occurrence: Ludlowville shale: Centerfield limestone member, USGS-SD 3503, 3571, 3593, USNM collection 1006; Ledyard 

member USGS ,3541-SD. Moscow shale: Windom member, 

USGS-SD collections 3548, 3553, 3559. Localities range from 

the Batavia quadrangle to Cayuga Lake.

The three syntypes of Dekayia devonica Ulrich 1890, 

here placed in the synonymy of P. clausus (see discussion p. 67) are from the Hamilton group, Eighteen 

Mile Creek. The geographic range therefore extends 

from Lake Erie to Cayuga Lake.

ATACTOTOECHID GROUP

Genera from the Hamilton group that display 

zooecial wall structure similar to that of the genus 

Atactotoeclius Duncan, are placed together. As seen 

in longitudinal section, the zooecial wall laminae of 

the included genera are relatively straight as they 

extend distally to the zooecial boundaries and they 

intersect the boundaries at various angles of less than 

90°. In tangential section the walls are generally 

integrate, but can appear amalgamate, depending on 

the angle that wall laminae make with the zooecial 

boundary (see p. 32 and fig. 13).

Genus ATACTOTOECHTJS Duncan

1939. Atactotoeclius Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 190.

Type species. Atactotoeclius typicus Duncan 1939.

Original definition. "Zoarium ramose or massive. 

Walls intermittently thickened, thickened zones laminated, thin zones granular. Cystiphragms in mature 

and occasionally in immature zones, usually resemble 

slightly curved complete or incomplete diaphragms, 

but, occasionally, cysts are closed. Diaphragms and 

cystiphragms more numerous opposite thick-walled 

parts of zooecia. Intermittent thickening is a regular 

feature of zoarial growth, hence crowded bands of 

diaphragms and cystiphragms developed at intervals. 

Mesopores absent, but small zooecia occasionally present. Acanthopores laminated, few or absent, usually 

restricted to monticules or groups of larger zooecia." 

(Duncan 1939)

Remarks. The definition of the genus is expanded 

to include incrusting zoaria and species containing 

mural spines. The granularity of the thin zones in the 

zooecial walls referred to in the generic definition 

above is due in part to poor preservation of the 

Traverse material. In well-preserved material the 

zooecial walls retain their laminated structure down to 

the point where the walls completely revert to neanic 

thicknesses. A complete reversion to neanic growth 

is not always attained but is common within the genus 

and is characterized by granular walls too thin to 

show laminae.

508025 O 60-
70 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

Cystiphragms, as used in the original generic definition, include transverse elements distinguished here 

as curved diaphragms, cystoidal diaphragms, and 

cystiphragms, all defined in the glossary on page 21. 

Also, the term mesopore as used in the present paper 

includes the small zooecia of the original definition.

In at least two species of Atactotoechus, A. cartus 

cartus (p. 73) and A. fruticosus (p. 76), diaphragms 

of the typical generic configuration and arrangement 

are confined almost entirely to monticular zooecia. Intermonticular zooecia in these species contain diaphragms that are generally planar and even spaced, 

giving no indication of generic affinities. The problem of the physiologic functions of the specialized 

zooecia in the monticules may never be solved because 

of the presumed extinction of the order near the end of 

the Paleozoic era. Nevertheless, the presence of important taxonomic characteristics in these zooecia 

makes the problem both intriguing and important in 

establishing a more natural classification of the 

Trepostomata.

The holotype of Paleschara reticulata Hall (1883, 

p. 179) described from the Hamilton group of York, 

New York, has a very thin incrusting zoarium. The 

zoarium displays the generic characters of Atactotoechus and the species is reassigned to that genus. The 

specimen is either so underdeveloped astogenetically 

that it does not possess characteristics of species described from the Hamilton group or it is a rare species 

that is not represented in later collections. Anomalotoechus tuberatus Duncan (1939, p. 188, pi. 1, figs. 

1-3) and Discotrypa vera Duncan (1939, p. 264, pi. 4, 

figs. 1-3) are here placed in Atactotoechus because of 

their atactotoechid wall structure and curved and 

cystoidal diaphragms. ? Amplexopora spinulifera 

Fritz (1930, p. 224, pi. 12, figs. 3-6) is reassigned to 

Atactotoechus. The published illustrations show a 

strongly integrate tangential section with few acanthopores and a weak development of curved and 

cystoidal diaphragms. Cyphotrypa? maculosa Duncan 

(1939, p. 199, pi. 5, figs. 17, 18) is placed in Atactotoechus with some doubt. The wall structure is atactotoechid but the diaphragms are not curved enough for 

a typical species of the genus.

The following species are now assigned to Atactotoechus :

acrituH Boardman, n. sp.

Ufoliatns Duncan 1939, p. 191, pi. 1, figs. 8-11

cartus Boardman, n. sp.

cartus Boardman, n. subsp.

pilatus Boardman, n. subsp. 

casei Duncan 1939, p. 192, pi. 2, figs. 1-3. 

crebcr Duncan 1939, p. 192, pi. 2, figs. 8-11. 

fruticosus (Hall) 1877 (part) (Redescribed on p. 76)

hunanensis Yang 1950, p. 4, pi. 1, figs. 1-4.

hystricosus Boardman, n. sp.

inornat-us Boardman, n. name

Iim1>atus Duncan 1939, p. 193, pi. 2, figs. 4-7.

lui Yang 1950, p. 5, pi. 1, figs. 5-7.

maculosns (Duncan) 1939.

parallelus Boardman, n. sp.

reticulatus (Hall) 1883.

spinuliferus (Fritz) 1930

spissus Duncan 1939, p. 195, pi. 3, figs. 1-4.

tuberatus (Duncan) 1939.

typicus Duncan 1939, p. 196, pi. 3, figs. 5-11.

verus (Duncan) 1939.

winchelli (Ulrich) 1890, p. 408, pi. 45, figs. 6, 6a.

Inferred phylogenetic lineages in Atactotoechus. 

Only NewT York species are considered in the construction of a phylogeny for the Hamilton species of Atactotoechus, as not enough is known of the genus from 

other depositional areas. A. acritus (p. 72) is a long 

ranging, stable species from which the other species 

of the genus seem to have evolved, either directly or 

indirectly (fig. 25).

The A. acritus-cartus lineage (fig. 25) is of interest 

because A. cartus (p. 73) is markedly different from 

any other species of the genus but seems to have 

evolved within the possibly short time represented by 

parts of the Ledyard and superjacent Wanakah shale 

members. Evidence for a direct connection between 

A. arcitus and A. cartus is fragmentary, but the appearance of the Ledyard member just preceding the 

first appearance of A. cartus of a specimen of A. 

acritus that in part developed the morphologic characteristics of A. cartus cartus is at least suggestive. 

The lineage is characterized by decreases in zooecial 

angle, width of the ephebic zone, and number of diaSTRATIGRAPHIC 

OCCURRENCE

Kashong 

(of Cooper, 1930)

Portland Point 

(of Cooper, 1930)

King Ferry shale 

(of Cooper, 1930)

Ledyard 

(of Cooper, 1930)

Centerfield 

limestone

New York species of Atactotoechus

No mural spine

cartus 

pilatus

(Wanakah)

Integrate, few

FIGUKE 25. Possible phylogenetic relationships of the New York species 

of the genus Atactotoechus.
SYSTEMATIC DESCRIPTIONS 71

phragms. BetAveen A. cartus cartus and A. cartus 

pilatus, the zooecial walls and diaphragms increase in 

thickness and the number of acanthopores decreases.

The A. acritus-hystricosus lineage includes the intervening species A. parallelus (p. 74) from the KingFerry shale member. In general, the lineage is morphologically comparable to the species of Atactotoechus 

described from the Skaneateles and Ludlowville 

equivalents of the Michigan Traverse section. The 

two groups of species are comparable in zooecial wall 

thicknesses, spacing and curvature of diaphragms, wide 

ephebic zones that have alternate thin- and thickwalled growth without the formation of basal laminae, 

and few or no acanthopores in intermonticular areas. 

In addition to these general similarities shared by the 

three New York species, the evidence for proposed 

phylogenetic connection AVI thin the NCAV York forms 

concerns progressive changes rather than detailed 

characteristics possessed by all. The lineage displays 

a progressive increase in zooecial Avail thickness and a 

decrease in the number of intermonticular acanthopores. The two oldest species, A. acritus and A. parallelus have comparable tangential sections, both appearing strongly integrate Avith subpolygonal apertures. 

HoAvever, the erratically curved and nonparallel diaphragms of A. acritus change to parallel structures 

of more uniform curvature in A, parallelus. A. 

parallelus and A. hystricosus (p. 75) both display 

parallel diaphragms but the tangential sections of 

A. hystricosus change; the thicker zooecial Avails appear narroAvly amalgamate, apertures are subcircular, 

and acanthopores are limited to the monticules.

A scatter diagram (fig. 26) for the A. acritus-hystricosus lineage shoAvs a shift to generally higher axial 

ratio values for similar groAvth stages as defined by 

the number of diaphragms. The bounding areas for 

each species shoAv considerable OA^erlap and this chart 

in itself could not serA^e to differentiate the species. 

Nevertheless, there is a shift in the same direction as 

the more pronounced shifts indicated for lineages in 

Leptotrypella (fig. 24) and Loxopliragma (fig. 27).

The presence of mural spines and nodes on the 

diaphragms of both A. hystricosus and A. fruticosus 

creates a problem in taxonomic interpretation (p. 

76). The spines are limited to these two species of 

Atactotoechus, which are knoAvn only from the Windom 

member and are considered to be essentially contemporaneous.

If the spines originated by genetic changes, A. 

fruticosus most likely evolved from an imknoAvn species

I i i i \ i I

EXPLANATION

Line bounding ami of plotted points of A. fruticosus, Windom 

member; 38 fragments from 22 zoaria

Line connecting the two plotted points of A. hystricosus, Windom 

member; 2 fragments from 2 zoaria

Line connecting the plotted points of A. parallelus, King Ferry 

member; A fragments from 1 zoarium

Line connecting the plotted points of A. acritus, Centerfield member; 8 fragments from 7 zoaria

1.00:1 0.80:1 0.70:1

AXIAL RATIO 

FIGDRB 26. Peripheral scatter diagram of species of Atactotoechus.
72 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

or subspecies of the A. parallelus-hystricosus lineage 

within the time represented by the Portland Point and 

Kashong members. (For geographic and stratigraphic relationships see fig. 5). The major morphologic change that distinguishes A. fruticosus from 

the A. parallelus-hystricosus lineage is an increase in 

zooecial wall thickness. Independent development of 

an identical attribute would have to be postulated if 

A. fruticosus is interpreted as originating from 

another lineage.

Environmental control is a second, and perhaps the 

most plausible explanation for the development of 

spines in the two species. The phenotypic expression 

of the spines might have been controlled by the environment, to the extent that the spines were genetically 

possible within the genus earlier in Hamilton time 

but were not developed until Windom time because 

of a change in environment. Unfortunately, a detailed 

petrologic study of the inclosing rock has not been 

made "and there is no known evidence for significant 

environmental change in the Windom. The third 

species of Atactotoechus occurring in the Windom 

member, A. acriius. is represented by only one fragment that does not show the spines and nodes.

Atactotoechus acritus Boardman, n. sp. 

Plate 17. figures 1-5

Diagnosis. Ramose and incrusting Atactotoechus 

(branches 5 to 10 mm in diameter) with moderately 

low monticules; erratically curved and non-parallel 

diaphragms and cystoidal diaphragms in many 

zooeci,a; zooecial walls integrate; acanthopores abundant for genus.

Description. Zoaria are ramose and incrusting and 

thin patchy layers of overgrowth occur on a few 

zoaria. Monticules are of low to medium height. Monticular zooecial walls are generally thicker than the 

walls of surrounding zooecia. Included acanthopores 

are larger and more abundant than in intermonticular 

areas. They develop large central canals, and commonly inflect the walls of the megazooecia. Monticular mesopores are few and are variously shaped in 

cross section.

In the neanic region, the zooecia have straight walls 

and few diaphragms. Abandoned growing tips are 

indicated at irregular intervals along the branches by 

remains of ephebic zones that arch across the branches 

and display various degrees of resorption.

In the ephebic region, the zooecial walls are fairly 

thin and display numerous irregular flexures and small 

variations in thickness. Within the ephebic zone, there 

is some alternation of neanic and ephebic growth without formation of basal laminations between the two

types of growth. In longitudinal sections, the zooecial 

boundary is normally marked by a dark line or narrow irregularly serrated zone of overlapping laminae. 

A few zooecia show thin zooecial linings in discontinuous patches just distal to the thicker diaphragms. The 

well-developed parallelism of repeated curved and 

cystoidal diaphragms that is common in other species 

of the genus is lacking in many zooecia. In these 

zooecia, curved and cystoidal diaphragms are more 

nonparallel and erratic in curvature and give the 

species a typically disordered look in longitudinal 

sections. Enclosed compartments formed by the 

cystoidal diaphragms thus vary considerably in size 

and shape. True cystiphragms (pi. 17, fig. 5) are very 

rare; only one zooecium displays them in each of 3 

of the 18 zoaria studied. Diaphragms and cystiphragms are generally thin but show an appreciable 

variation in thickness. Compound diaphragms are 

rare.

In tangential view, zooecia have polygonal to subpolygonal apertures. The zooecial walls are integrate, 

the zooecial boundaries light to transparent. Some 

zooecia appear amalgamate because the straight laminae intersect the boundaries at high angles. Close 

inspection however, reveals the transparent sharply 

defined zooecial boundary, making the zooecia integrate by definition. Acanthopores are unusually numerous in intermonticular areas, and inflect the zooecial 

Avails if located between zooecial corners. Mesopores 

are rare outside of the monticules. Curved and 

cystoidal diaphragms are commonly seen as loops in 

the voids of the zooecia in tangential sections.

The following table is based on 13 sectioned fragments from 12 zoaria. Sections from 18 zoaria of 

A. acritii.fi were examined.

Diameter of zoarium____________mm__

Width of neanic zone__ ________ do ____

Zooecia in 2 mm_____________________

Average diameter of zooecia per zoarium. _____________________ _mm_ _

Diameter of megazooecia. ______ do.___

Acanthopores per zooecium___________

Diaphragm ratio. __.__--____---_-____

Ontogeny

Minimum Maximum

5. 2 9. 9

3. 7 7. 0

6 7

. 20

Rare 

1:1

. 29 

. 50 

. 40 

4:1

Average number of diaphragms

0_____-________________________.

Width, of 

ephebic zone 

(mm)

1.2

1.3-1.5

1.6-1.7

2. 3

2. 9

2.5

Axial ratio

.82

. 75-. 82

AQ_ 74

. 72

. 71

. 63

Remarks. Two ramose fragments of A. acritus 

were collected from the Ledyard member. One of the
SYSTEMATIC DESCRIPTIONS 73

specimens is comparable with the holotype. Part of 

the longitudinal section of the second specimen (pi. 

17, fig. 2) is typical of A. acritus. but other parts of 

the section closely resemble A. cartus cartus. The only 

ramose specimen from beds younger than the Ledyard 

is a fragment from the Winclom member that is morphologically similar to the holotype of A. acritus 

except for a scarcity of acanthopores. For further discussion see p. 70).

A. acritus differs from Atactotoechus creber Duncan 

(1939, p. 192, pi. 2, figs. 8-11) in displaying less 

parallelism of diaphragms, more strongly curved diaphragms and cystoidal diaphragms, fewer diaphragms 

in the neanic region, and apertures that are more 

strongly polygonal. Atactotoechus spissus Duncan 

(1939, p. 195, pi. 3, figs. 1-4) differs from A. acritus in 

possessing regularly spaced diaphragms throughout the 

neanic region. A. acritus differs from Atactotoechus 

typicus Duncan (1939, p. 196, pi. 3, figs. 5-11) in the 

different growth habit and less well developed 

parallelism of the diaphragms.

Types: Holotype USNM 133926 from USGS collection 

3561-SD; figured paratypes USNM 133927-133930.

Occurrence: Lutllowville shale: Centerfleld limestone member, USGS-SD 3503, 3529, 3561, 3571, 3593; Ledyard member 

of Cooper (1930), USGS 3541-SD; Wanakah shale member as 

used by Bueliler and Tesmer (in press), USGS 3516-SD, USNM 

collection 1017. Moscow shale: Windom member, USGS 

3559-SD. Localities range from Lake Erie to Cayuga Lake.

Atactotoechus cartus Boardman, n. sp. 

Plate 18, figures 1-6

Diagnosis. Polytypic species of small ramose zoaria 

(maximum observed diameter of branches 9.3 mm) 

characterized by unusually low zooecial angles, narrow ephebic zones, and few diaphragms; curved and 

cystoidal diaphragms typical of the genus largely restricted to zooecia of monticules, intermonticular diaphragms generally planar and parallel.

Remarks. Two chronological subspecies are recognized within A. cartus, A. cartus cartus from the Wanakah shales member and Portland Point member and 

A. cartus pilatus from the Kashong member overlying 

the Portland Point member. The two subspecies have 

morphologic characters primarily low zooecial angles, 

narrow ephebic zones and few diaphragms, that are 

greatly different from the other known species of 

Atactotoechus. The morphologic uniqueness and stratigraphic relationships indicate a direct phylogenetic 

connection between the two taxa.

Type: Holotype USNM 133935 from USGS collection 

3551-SD.

Occurrence: Wanakah shale member (as used by Buehler 

and Tesmer in press) of the Ludlowville shale and the Portland Point and Kashong member (of Cooper, 1930) of the 

Moscow shale from the Buffalo quadrangle to Seneca Lake. 

(For complete listing of collection numbers see p. 74).

Atactotoechus cartus cartus Boardman, n. subsp. 

Plate 18, figures 4-6

Diagnosis. Zoaria ramose; branches small, 3 to 9 

mm in diameter; monticules generally high; zooecial 

angles unusually low, average 62° ; diaphragms few 

(maximum of 12 observed) and generally thin, zooecial 

walls increase gradually in thickness in early ephebic 

zone.

Description. The ramose zoaria form dense clumps. 

Conspecific overgrowth is rare. Monticules are generally high. The included megazooecia have slightly 

thicker walls, and generally have a few more diaphragms than intermonticular zooecia. The monticular diaphragms tend to be planar and parallel, inclined to each other and irregularly curved, or parallel 

and regularly curved, Cystoidal diaphragms are 

'abundant in the monticules. Monticular mesopores are 

very rare and acanthopores show little increase in 

number or size over intermonticular acanthopores.

The zooecia reach the surfaces of the zoaria at unusually low angles, averaging approximately 62° 

instead of the usual 80°-90° for the genus. No definite 

zooecial bend is developed. ; The most advanced growth 

stages show relatively few diaphragms (maximum observed is 12) and narrow ephebic zones for a species 

of Atactotoechus. In most zooecia the zooecial walls 

increase gradually in thickness in the early ephebic 

zone. After the third or fourth diaphragm the wall 

thickness may continue to increase slowly or become 

irregular. The zooecial walls are typically atactotoechid (p. 32). In longitudinal sections, the zooecial 

boundaries are marked by light or black lines or narrow serrated zones of overlapping laminae. The light 

or dark shading of the boundaries may be discontinuous along any one boundary. Planar and parallel 

diaphragms are the rule in the early ephebic zones and 

occur throughout many intermonticular zooecia. 

Curved and cystoidal diaphragms are common in other 

zooecia after the fourth or fifth diaphragm but are not 

generally as strongly curved as the diaphragms of the 

zooecia in the monticules. The diaphragms are generally thin, but a few are conspicuously thick..

In tangential view, the zooecia have polygonal to 

subpolygonal apertures. The zooecial walls are integrate, the zooecial boundaries appearing as almost invisible light lines. Acanthopores are variable in number within a zoarium, and in a few sections are unusually numerous for the genus. The acanthopores 

have a well-defined central tube, and ordinarily occur 

in the zooecial corners. Mesopores are rare to absent.
74 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

The following table is based on 152 sectioned fragments from 13 zoaria. Sections from 15 zoaria of 

A. cartus cartus were examined.

Minimum Maximum

Diameter of zoarium._.__._......_. mm._ 2. 8 9. 3

Width of neanic zone.............do.-.. 2.3 7.8

Zooecial surface angle-_--.__._._._._--. 32° 86°

Zooecia in 2 mm._^.__._.._.____..._--._ 5 7

Average diameter of zooecia' per fragment

mm.. .17 .26

Diameter of megazooecia_________do.... ._____._ .50

Acanthopores per zooecium___.____-._-_ Very rare . 60

Mesopores per zooecium._...___......__ Very rare . 20

Ontogeny

Width of

1-3.

4...

7 '_ 

9. 

11

fphebic zone

Average number of diaphragms (mm) Axial ratio

............................ . 4- . 9 . 78-. 93

-_____'-__--_-_---__ ______--- .8-1.2 . 75-. 83

._..-.._---------_....-_.--_ .9-1.5 . 71-. 84

.--_-.._---------__.-------. 1.2-1.6 .69-79

.._.__...-_.-...-.-_.-_._-.- 1.6 .71

.._.-...__-...-_-_-_..._---. 1.8 .68

ftemarks. Zoaria from the Portland Point member 

occur in isolated lens-shaped concentrations of broken 

fragments, each mass presumably representing one 

zoarium. (For further discussion see p. 36). In 

support of this assumption, all of the fragments of one 

of the concentrations displayed constant morphologic 

characteristics that were noticeably at variance with 

fragments from the other 12 concentrations. The 

variant zoarium possesses relatively well-defined zooecial bends, generally higher zooecial angles, longer 

living chambers, and a generally wider ephebic zone 

for any one growth stage as defined by numbers of 

diaphragms. Constancy of variant morphologic characteristics throughout the concentration of fragments 

suggests that only one zoarium is represented. Such 

constancy is expected in a zoarium if it can be assumed that all of the individuals of a colony possess 

the same genetic constitution and therefore display 

phenotypically most of the same variant morphologic 

characters.

Only one fragment was collected from the Wanakah 

shale member.

Types: Holotype USNM 133935 from USGS collection 

3551-SD; figured paratypes USNM 133937, 133939.

Occurrence: Lucllowville shale: Wanakah shale member 

as used by Buehler and Tesmer (in press), USGS 3515-SD, 

Buffalo quadrangle. Moscow shale: Portland Point member 

of Cooper (1930). USGS 3551-SD. Cananclaigua Lake.

Atactotoechus cartus pilatus Boardman, n. subsp.

Plate 18, figures 1-3

Diagnosis. Kamose subspecies differentiated from 

the nominate subspecies by many thick diaphragms

causing abrupt increases in thickness of generally thick 

zooecial walls; monticules of low to medium height; 

maximum observed number of diaphragms 6; acanthopores small and rare, generally limited to monticules.

The major morphologic differences between A. cartus 

cartus and A. cartus pilatus are the thick development 

of both diaphragms and zooecial walls in A. cartus pilatus. A. cartus cartus displays thickened diaphragms 

and walls in random zooecia of a relatively few zoaria. 

These morphologic differences are considered marked 

and constant enough to be useful for distinguishing 

the Kashong shale member from lower members if a 

reasonable number of specimens are available. Except 

for generally fewer acanthopores in A. cartus pilatus 

(maximum acanthopore ratio: 0.32:1), no important 

differences were found between the subspecies in the 

quantitative measurements made.

The small numbers of diaphragms and the narrow 

ephebic zones of A. cartus pilatus are either characteristics of the subspecies or indicate that the material 

studied came from young zoaria or younger parts of 

zoaria. Ninety-three longtitudinal slides were studied 

from seven Kashong localities. The fragments sectioned were chosen at random. At Menteth Creek 

(Collection 3552) one compressed mound of fragments 

and branches of A. cartus pilatus measured 4 feet in 

diameter and 6 inches in height. Due to the compressed condition of the mass and the hard enclosing 

matrix it was impossible to determine the number of 

zoaria represented. Pieces were collected from eight 

places in this mass and thin-sections were made from 

all 8 collections. The maximum number of diaphragms 

seen was five. Thus it seems that small numbers of 

diaphragms and narrow ephebic zones are characteristic of the subspecies. Sections from 45 zoaria were 

examined.

Types: Holotype USNM 133934 from USGS collection 

3552-SD; figured paratypes USNM 133932, 133933.

Occurrence: Kashong member (of Cooper, 1930) of the 

Moscow shale, USGS-SD 3500, 3501, 3531, 3543, 3552, 3558 and 

collection (35). Localities range from the Attica quadrangle 

to Seneca Lake.

Atactotoechus parallelus Boardman, n. sp. 

Plate 17, figure 6

Diagnosis. Zoaria large, ramose; in ephebic zone 

zooecial walls thin, diaphragms uniformly thin, parallel, generally planar to slightly curved, monticular 

diaphragms more strongly and irregularly curved; in 

tangential view zooecial walls strongly integrate.

Description. Zoaria are ramose. Primary branches 

of the holotype zoarium are covered by a thick con-
SYSTEMATIC DESCRIPTIONS 75

specific overgrowth. Monticules are high. Monticular zooecia have thickened walls and are irregular in 

shape as seen in tangential sections. Included diaphragms are more strongly and irregularly curved 

and more irregularly spaced than those of intermonticular zooecia. Monticular acanthopores are numerous, enlarged, and strongly inflect the zooecial walls. 

Individual monticules contain only 2 or 3 mesopores.

In the neanic region, zooecial walls are straight to 

irregularly flexed. Diaphragms occur in widely spaced 

zones arching across the neanic region. As many as 

15 diaphragms, irregularly spaced, are displayed in a 

zooecium within an arched zone. Some zooecial wall 

thickening occurs opposite the more closely spaced 

diaphragms indicating positions of abandoned growing tips.

In the ephebic region, zooecial walls are thin and 

display numerous irregular flexures and small variations in thickness. Zooecial boundaries are marked 

by a dark line or narrow irregularly serrated zone 

of overlapping laminae. Diaphragms are uniformly 

thin, parallel, and generally planar to slightly curved. 

Cystoidal diaphragms are not common outside of the 

monticules. Cystiphragms and compound diaphragms 

are very rare.

In tangential view, zooecia have polygonal to subpolygonal apertures. The zooecial walls are strongly 

integrate; the zooecial boundary appears as a welldefined light to dark line. Acanthopores are rare 

betAveen monticules, small, and not confined to zooecial 

corners. Intermonticular mesopores are very rare to 

absent.

The following table is based on 4 sectioned fragments from the only zoarium of A. parallelus available for study.

Minimum Maximum

Diameter of zoarium._..____._..__mm__ 9. 1 15. 5

Width of neanic zone____--_______do-__- 6.5 7.9

Zooecia in 2 mm.______________________ 6 7

Average diameter of zooecia per fragment

mm.. .26 .29

Diameter of megasfooecia.........do.... ________ .41

Acanthopores per zooecium _____________ Very rare . 30

Ontogeny

10. 

15. 

24.

28.

Width of 

ephebic zone 

Average number of diaphragm? (mm) Axial ratio

............................ 2.6 .71

..........--..-....._____... 3.8 .65

..-...-.--____.__........... 6.6 .50

............................ 7.6 .51

Remarks. Atactotoeclms casei Duncan (1939, p. 

192, pi, 2, figs. 1-3) differs from A. parallelus in its 

massive growth habit and low monticules containing 

acanthopores that do not noticeably inflect zooecial

walls. A. casei has integrate walls with light zooecial 

boundaries. Atactotoechus creber Duncan (1939, p. 

192, pi. 2, figs. 8-11) differs from A. parallelus in having narrowly amalgamate walls and extreme crowding 

of diaphragms in short zones opposite zooecial wall 

thickening in the ephebic region. Atactotoechus limbatus Duncan (1939, p. 193, pi. 2, figs. 4-7), A. spissus 

Duncan (1939, p. 195, pi. 3, figs. 1-4), and A. typicus 

Duncan (1939, p. 196, pi. 3, figs. 5-11) all have conspicuously thickened zooecial walls and diaphragms, 

differing mainly in this characteristic from A. parallelus.

Type: Holotype USNM 133931 from USGS collection 

3564-SD.

Occurrence: King Ferry shale member (of Cooper, 1930) 

of the Ludlowville shale, USGS 3564-SD, Cayuga Lake.

Atactotoechus hystricosus Boardman, n. sp. 

Plate 20, figures 1, 2

Diagnosis. Zoaria ramose; in ephebic zone zooecial 

walls moderately thick and irregularly undulate; diaphragms planar to strongly curved and cystoidal, 

parallel, variable in thickness, many compound; small 

mural spines and nodes on distal sides of many diaphragms; in tangential view zooecial walls generally 

narrowly amalgamate, apertures subcircular to subpolygonal; acanthopores limited to monticules.

Description. Zoaria are ramose. Conspecific overgrowth is common. Monticules are high. Monticular 

zooecial apertures are subtriangular to subpolygonal. 

Zooecial walls are thickened and generally integrate. 

Monticular diaphragms are either strongly curved 

forming repeated, parallel series of cystoidal diaphragms and a few cystiphragms, or planar, parallel, 

and closely spaced. Cystiphragms are very rare. 

Monticular acanthopores are few, small, generally at 

zooecial corners, and cause little inflection of zooecial 

walls. Mesopores are few and irregularly scattered 

in monticules.

In the neanic region, zooecial walls are straight to 

irregularly flexed. Few diaphragms occur in widely 

spaced zones arching across the neanic region.

In the ephebic region, zooecial walls are moderately 

thick and generally irregularly undulating as seen in 

longitudinal sections. Wall thickness is extremely 

irregular, commonly changing with the addition of 

thicker diaphragms. Wall thickness is further complicated by an alternation of thin- and thick-walled 

growth within the generally ephebic region. A basal 

lamination is not developed at the beginning of thinwalled growth as in the more common overgrowths. 

Zooecial boundaries are marked by a light to dark, 

narrow, irregularly serrated zone of overlapping
76 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

laminae. Diaphragms range from planar to strongly 

curved and generally are arranged in parallel series 

within a zooecium. Cystodial diaphragms are common 

and similarly arranged. Diaphragms are moderately 

variable in thickness; thicker diaphragms are commonly compound. Small mural spines and nodes are 

abundant on the distal sides of many diaphragms but 

are rare on the zooecial walls.

In the tangential view, zooecia have subcircular to 

subpolygonal apertures. The zooecial walls are generally narrowly amalgamate. A few intermonticular 

zooecia and most of the monticular zooecia are integrate. Acanthopores are. limited to the monticules. 

Mesopores are very rare. Interiors of the zooecia in 

tangential sections are characterized by the curved and 

cystoidal diaphragms that appear as semicircles of 

laminated material, and the minute spines on the diaphragms that appear as small circles and dots.

The following table is based on 4 sectioned fragments from the 4 available zoaria of A. hystricosus.

Diameter of zoarium______________mm__

Width of neanic zone_____-_______do____

Zooecia in 2 mm.______________________

Average diameter of zooecia per fragment

mm_^ 

Diameter of megazooecia. ________do____

Minimum Maximum

8. 1 12. 3

5. 5 8. 1

. 20 . 23 

. 44

Ontogeny

Average number of diaphragms

Width of

ephebic zone

(mm)

13.

16.

17. 

20.

Axial ratio

2. 6 .68

4. 1 _.....__.

3. 9 __.__....

4. 2 . 66

Remarks. A. hystricosus and A. fruticosus are both 

limited to the Windom member of the Moscow shale 

and are the only known species of Atactotoechus displaying the small mural spines and nodes on the diaphragms. The apparently simultaneous appearance of 

a new attribute in two species of a genus creates a 

problem in phylogenetic interpretation (see p. 71).

Fundamental to the problem is the correctness of 

dividing the Windom material into two species. A. 

hystricosus differs from A. fruticosus in displaying 

thinner more undulating zooecial walls in the ephebic 

zones, more strongly curved diaphragms, narrowly 

amalgamate walls, and acanthopores limited to the 

monticules. A. hystricosus occurs only in the easternmost locality of the region studied and the range of 

morphologic variation is poorly known as the size of 

the sample is inadequate. A. fruticosus is not found 

in the easternmost locality but is very common in most 

of the other localities of the Windom member and is

distinctive and well known. Specimens placed in A. 

fruticosus are relatively constant for the genus in 

morphologic characteristics and there are no known 

specimens that are transitional or even approach the 

morphologic characteristics of A. hystricosus.

Probably the most significant morphologic difference 

between the two groups is the narrowly amalgamate 

appearance of A. hystricosus as opposed to the generally integrate appearance of A. fruticosus. The 

complete range of variation of amalgamate or integrate appearance within a species is generally determinable in 2 or 3 randomly selected tangential sections. 

Thus, the amalgamate characteristic in A. hystricosus is fairly well established. Also, if specimens 

now placed in A. hystricosus were merely thin-walled 

variants of A. fruticosus, they would most certainly 

be more strongly integrate as is the general rule in 

thin-walled variants of species of Atactotoechus. The 

narrowly amalgamate appearance of A. hystricosus 

therefore most likely indicates fundamental differences 

between the two groups in the pitch and configuration of the wall laminae. This difference in laminae is 

perhaps better interpreted as genetic rather than 

environmental and the two groups are thus considered separate species.

Types: Holotype USNM 133945 from USGS collection 

3570-SD; figured paratype USNM 133946.

Occurrence: Windom member of the Moscow shale, USGS 

3570-SD, Fillmore Glen State Park, Moravia quadrangle.

Atactotoechus fruticosus (Hall) 1877 

Plate 19, figures 1-6; plate 20, figures 3, 4

1877. Chaetetes fruticosus Hall (part), New York State Geol. 

Survey, Paleontology, pi. 38, fig. 2.

1877. Cliactetes furcatus Hall (part), New York State Geol. 

Survey, Paleontology, pi. 37, fig. 5.

103!). Atactotocclius fruticosus (Hall) Duncan, Univ. Michigan, Mus. Paleontology, Contr., v. 5, p. 190.

Diagnosis. Zoaria large, ramose, and incrusting 

zooecial walls uniformly thick in ephebic zone; diaphragms thin, generally planar, parallel and evenly 

spaced in intermonticular zooecia, curved and cystoidal in monticules, small mural spines and nodes 

generally on distal sides of diaphragms in most zoaria; 

zooecia integrate, few narrowly amalgamate, apertures 

unusually small.

Description. Zoaria are ordinarily ramose and 

rarely incrusting, or can be a combination of the two 

growth habits. Branches are large, ranging from 5 

to 17 mm in diameter. Thick incrusting layers of 

conspecific overgrowth are common. The branches 

may display bulbous to irregular swellings, caused by 

concentrations of thicker layers of overgrowth or 

alternating zones of thick and thin zooecial walls that
SYSTEMATIC DESCRIPTIONS 77

elongate the zooecia within the ephebic zone (see below). Monticules are variable in height, but most 

commonly are high. Included megazooecia have 

strongly thickened walls, and most display an irregular growth habit. Monticular diaphragms are strongly 

curved and cystoidal. As many as 5 or 6 polygonal 

mesopores occur within a monticule. Acanthopores in 

the monticules are increased in number and size over 

intermonticular acanthopores and some are inflected 

far into adjacent zooecial cavities as seen in tangential sections.

In the neanic region, zooecial walls are generally 

uncrenulated and straight. Diaphragms occur in 

.irregularly spaced zones arching across the neanic 

region and probably indicate positions of abandoned 

growing tips. A few abandoned tips show no signs 

of resorption (pi. 19, fig. 4) but most have only the 

first 2 or 3 diaphragms remaining.

In the ephebic zone, specimens showing growth 

stages of 7 diaphragms or more generally have a 

zooecial angle of greater than 80°. Zones of thin 

zooecial Avails that interrupt normal thick-walled development are common within the ephebic regions. 

A basal lamination is not developed at the beginning 

of this thin-walled growth as in the more common 

overgrowths. The thin walls within the ephebic zones 

generally retain a finely laminated structure similar 

to the thick walls, so do not completely lose their 

ephebic construction. In the extreme development, the 

thin-walled zones revert to neanic walls that are characteristically thin and granular and may extend 

locally to form a neanic zone for a secondary branch. 

Diaphragms are more widely spaced opposite the 

thin-walled zones.

If not complicated by alternate thick and thinwalled growth, the zooecial walls increase rapidly and 

uniformly in thickness in the early ephebic zone and 

are unusually thick for Atactotoechus. In most longitudinal sections the zooecial boundary is generally 

marked by a dark line or narrow, irregularly serrated 

zone of overlapping laminae. In a few specimens, 

zooecial boundaries are light in shading or are not 

definable, the laminae from adjacent zooecia appearing continuous. Diaphragms are commonly thin, 

many of the thicker diaphragms are compound. The 

majority of intermonticular diaphragms are planar 

to slightly curved, parallel, and evenly spaced. In a 

few zoaria curved and cystoidal diaphragms are common at the zooecial bends. The curved and cystoidal 

diaphragm development typical of the genus occurs 

more commonly in the monticular zooecia. Small 

mural spines and nodes appear on the diaphragms 

(pi. 20, figs. 4a, 4b) in most of the zoaria examined.

The spines occur most commonly on the distal sides 

of the thicker diaphragms, less commonly on the 

zooecial walls and very rarely on the proximal sides 

of the diaphragms. The spines are generally about 

equally distributed throughout a zoarium, and range 

from abundant to none in different zoaria.

In the tangential view zooecia have unusually small 

subpolygonal to subcircular apertures due to the 

thickened zooecial walls. The zooecial walls are generally integrate but a few appear narrowly amalgamate. The zooecial boundary is light to transparent 

and difficult to define, which may account for the 

narrowly amalgamate appearance of many zooecia. 

Acanthopores are rare outside the monticules and are 

confined to the corners of zooecia. The acanthopores 

are generally small but may cause slight inflection in 

the zooecial walls. Mesopores are very rare outside 

the monticules.

The following table is based on 40 sectioned fragments from 22 zoaria. Sections from 42 zoaria of A. 

fruticosus were examined.

Minimum Maximum 

Diameter of zoarium._._____..----.mm.. 4.9 16.9

Width of neanic zone____.-__---_-do_.-_ 3.9 13.2

Zooecial wall thickness ----------do..__ .04 .12

Diaphragm ratio.__________--_.-----_-_ 1:1 4:1

Zooecia in 2 mm____ ___________________ 6J4 8*4

Average diameter of zooecia per fragment

mm.. .14 . 23 

Diameter of megazooecia.......--do.... _._._--. .45

Ontogeny

Number of diaphragms

3-4.. 

5-6...

7-8...

8-10.. 

11-14. 

15-18. 

23-25. 

27...

Width of 

ephebic zone

(mm) Axial ratio

0. 7-1. 1 . 80-. 93

1. 1-1. 7 . 72-. 87

1. 8-2. 0 . 74-. 81

1. 9-2. 6 . 70-. 84

2. 3-3. 7 . 67-. 78

3. 7-4. 1 . 64-. 67

4. 9 . 63

4. 8 .61

Remarks. Hall (1877, pi. 38, figs. 1-5) erected 

Chaetetes fruticosus, figuring three unsectioned syntypes and giving no written description. Duncan 

(1939, p. 190) reassigned C. fruticosus to Atactotoechus. Thin sections show that one of the syntypes 

(NYSM 6182, pi. 38, fig. 2) does belong to the genus 

Atactotoechus and this specimen is here designated 

as the lectotype of Atactotoechus fruticosus (Hall) 

1877. The remaining two syntypes (Hall, pi. 38, figs. 

1, 5) are conspecific with Leptotrypella asterica (p. 

58) and are considered only as identified specimens 

of L. asterica.

Sectioning of syntypes of Chaetetes furcatus Hall 

1877, revealed one specimen (NYSM 6186, pi. 37, fig.
78 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

5) that is conspecific with the lectotype df A. fruticosus (Hall) and is now placed in A. fruticosus. For 

a more complete history of Atactotoechus fruticosus 

see p. 60.

Types: Lectotoype NYSM no. 6182 (Hall, 1877, pi. 38, fig. 

2) Hamilton group, Canandaigua Lake, New York; figured 

specimens USNM 133940-133944, 133947.

Occurrence: Windoin member of the Moscow shale, 

USGS-SD 3548, 3553, 3559, 3562, 3569, 3575, 3579, 3585. Localities range from the Genesee Valley to Cayuga Lake.

Atactotoechus inornatus Boardman, n. name

1939. Stir/matella hybrid a Duncan, Univ. Michigan, Mus. 

Paleontology Cont., v. 5, p. 234, pi. 5, figs. 9-10.

/Stigmatella hybrida Duncan 1939, is a junior primary homonym of /Stigmatella liy~brida Dyer (1925, 

p. 71, pi. 4, figs. 7, 8, pi. 7, fig. 1), a species described 

from the Upper Ordovician of Ontario. At Miss 

Duncan's request, the specific name inornata is here 

substituted objectively for hybrida of Duncan. The 

type specimen bearing the new name inornata is interpreted to belong to the genus Atactotoechus Duncan 

1939, thus the type of Stigmatella hybrida Duncan 

1939 is now named Atactotoechus inornatus Broadman, 

n. name.

Remarks. The holotype sections display strongly 

atactotoechid walls (p. 32). Diaphragms are generally parallel to each other and are not strongly 

curved. However, the diaphragms are few, which may 

indicate a young growth stage for the holotype. In 

addition to the utricular growth habit, incrusting 

forms of A. inornatus are known from the type locality in the Bell shale of Michigan. No representatives 

of the species were found in the New York Hamilton 

group.

Genus LOXOPHRAGMA Boardman, n. gen.

Type species. Loxophragma lechrium Boardman, 

n. sp.

Diagnosis. Zoaria ramose and incrusting, diaphragms typically planar to slightly curved, closely 

and irregularly spaced, non-parallel, both simple and 

compound; wall structure atactotoechid, integrate, 

rarely narrowly amalgamate; acanthopores laminated, 

small, variable in number; mesopores largely confined 

to monticules.

Description. Zoaria are ramose, incrusting, or a 

combination of both habits. Ramose forms branch 

dichotomously. Conspecific overgrowth is generally 

present in varying amounts. Monticules are variable 

in height, evenly spaced in a zoarium, and contain 

megazooecia, zooecia, mesopores, and acanthopores in 

varying numbers.

The neanic region is nondiagnostic, displaying thin, 

granular walls that range from straight to tightly

crenulated. In ramose forms, remnants of either 

eroded or resorbed growing tips are common.

In the ephebic zone, zooecial walls display an atactotoechid wall structure (p. 32). As seen in longitudinal sections the traces of the wall laminae 

approaching the zooecial boundaries generally remain 

straight and intersect the boundaries at angles of less 

than 90°. The zooecial boundary is generally narrow 

and well defined by the intersection of laminae, but 

in some individuals or species, laminae appear to be 

continuous across the boundary. The zooecial walls 

end distally in sharp edges controlled by the configuration of the laminae.

The diagnostic characteristics of the genus are found 

in the spacing and configuration of the diaphragms. 

Typically, diaphragms are closely and irregularly 

spaced, slightly inclined or nonparallel to each other, 

and planar to slightly curved. Relatively small, narrow, triangular (in two dimensions) compartments are 

commonly formed by the intersection of two adjacent 

nonparallel diaphragms. These triangular compartments are generally distinguishable from the rounded 

compartments formed by strongly curved cystoidal 

diaphragms that are characteristic of Atactotoechus 

(p. 69). Typical, closely packed nonparallel diaphragms occur either throughout a zoarium or are 

limited to the zooecia of the monticules. Species displaying the crowded nonparallel diaphragms only in 

the monticules have planar, more nearly parallel and 

evenly spaced diaphragms in intermonticular zooecia. 

Diaphragms are generally variable in thickness; the 

thicker diaphragms are commonly compound. Single 

nodes or thick short spines may occur on the distal 

sides of thicker diaphragms.

In tangential sections, zooecial walls are generally 

integrate with light, transparent zooecial boundaries. 

Narrowly amalgamate structure is rare. Acanthopores 

are laminated and small, and their numbers and distribution can be extremely variable within a zoarium 

or species. Mesopores are largely confined to the 

monticules.

Remarks. Loxophragma is most closely related to 

the genus Atactotoechus and is placed in the same 

family grouping with that genus. Both genera are 

characterized by atactotoechid wall structure and close 

spacing of both simple and compound diaphragms. 

Atactotoechus is characterized by strongly curved cystoidal diaphragms arranged in parallel series within 

a zooecium. The diaphragms of Loxophragma are 

readily distinguishable from those of Atactotoechus, 

exhibiting a markedly disorderly nonparallelism and 

irregular spacing of planar to slightly curved diaphragms.
SYSTEMATIC DESCRIPTIONS 79

Eridotrypella spinifera Duncan (1939, p. 218, pi. 7, 

figs. 6, 7) and Eridotrypella valida Duncan (1939, 

p. 219, pi. 7, figs. 12-14) display an atactotoechid wall 

structure and the diaphragm arrangement of Loxophragma and are here reassigned to Loxophragma. 

Leptotrypella varia Duncan (1939, p. 232, pi. 10, figs. 

1-3) has an atactotoechid wall structure. Microscopic 

examination of the holotype slide indicates the specimen is complicated by an atypical overgrowth. The 

side of the branch opposite the side figured by Duncan displays the primary zooecia containing diaphragms typical of Loxophragma, so L. varia is now 

placed in Loxophragma.

inferred phylogenetic lineage in Loxophragma. 

Two species of Loxophragma are described in the New 

York Hamilton and quantitative evidence indicates 

phylogenetic connections between them. L. leptum 

(below) is the older species, occurring in the Centerfield limestone member. L. leptum is thought to give 

rise to L. lechrium,, a species occurring in the Ledyard, Wanakah shale, and Tichenor limestone members and the partly equivalent King Ferry shale 

member of the Ludlowville shale, and the Kashong 

member of the Moscow shale. Evidence for the phylogenetic connection is found mainly in a three step 

increase in axial ratios for approximately equivalent 

growth stages (fig. 27). This increase correlates with 

stratigraphic position and parallels a similar increase

in axial ratios in the same stratigraphic positions in 

the genera Leptotrypella (fig. 24) and Atactotoechus 

(fig. 26).

The increase in axial ratios is controlled by increase 

in neanic diameters, the major difference between the 

two species of Loxophragma. The increase in neanic 

diameter increases the total branch diameter of L. 

lechrium but there is little difference in the ephebic 

zone dimensions for any one growth stage in the two 

species. Thus, axial ratios of L. lechrium are considerably higher than those of L. leptum for any one 

growth stage. The intermediate position (fig. 27) of 

the three specimens of L. lechrium from the Ledyard 

member indicates that they are transitional between 

forms above and below, morphologically as well as in 

time. The Ledyard specimens probably could be considered a subspecies if adequate material were available. In addition to the increase in axial ratios and 

neanic diameters, the lineage shows an increase in 

the height of monticules and an apparent ability to 

develop to more advanced growth stages as determined 

by the numbers of diaphragms.

Loxophragma leptum Boardman, n. sp. 

Plate 21, figures 5-8

Diagnosis. Small ramose Loxophragma (maximum 

diameter of branches about 4 mm) with low monticules; distinguished by its small axial ratio and more

Ctf

DC 

PL, 12

~\ i r n i r n i i r

EXPLANATION

Line bounding area of plotted points of L. lechrium, from Wanakah, 

Tichenor, King Ferry and Kashong members

X 

Plotted points of L. lechriiim from the Ledyard member

Line bounding area of plotted points of L. leptum, Center field 

member

0.65:1 

AXIAL RATIO

FIOURK '27. Peripheral scatter diagram of the New York species of Loxophragma and individual measurements of the holotype sections of 

species described by Duncan (1930) fro.m the Traverse group of Michigan and reassigned to Loxophragma.
80 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

nearly parallel, less cystoidal diaphragms in intermonticular parts of zoarium.

Description. Zoaria are small and ramose, and 

overgrowth is rare. Monticules are low and include 

several megazooecia, zooecia, and 2 or 3 mesopores. 

Some megazooecia have thickened walls. Acanthopores 

are always present in the monticules and are not 

appreciably larger than those in intermonticular 

regions.

In the ephebic zone, zooecial walls increase in thickness uniformly and attain their maximum thickness 

distal to the zooecial bend. Zooecial boundaries are 

light in shading and poorly defined in longitudinal 

views. Diaphragms are variable in thickness; thicker 

diaphragms are commonly compound. Diaphragms 

are generally planar and closely spaced. Many are 

inclined to each other and form compartments of various shapes, especially in the zooecia of the monticules. 

Intermonticular zooecia display diaphragms more 

nearly parallel to each other.

In the tangential view, apertures are subcircular in 

thicker Availed zooecia, subpolygonal in thinner walled 

zooecia. Walls in tangential sections are typically 

integrate, rarely narrowly amalgamate. Acanthopores 

are extremely variable in number, small, possess welldefined central tubes, and are generally located at the 

zooecial corners.

The following table is based on 13 sectioned fragments from the 10 available zoaria of L, leptum.

Diameter of zoarium___-________mm__

Width of neanic zone..._______..do..___

Zooecial wall thickness-______.._do..___

Zooecia in 2mm._______._.._____.___

Average diameter of zooecia per fragment. --_______--___-______.. _mm__

Diameter of megazooecia_ _____ _do_

Acanthopores per zooecium. __________

.Minimum 

2. 0 

1. 2 

. 06

. 17 

. 18

Ontogeny

Average number of diaphragms

Width of

ephebic zone

(mm)

0. 8-1. 6

1. 8-1. 9

2. 3

2. 0

Maximum

3. 8 

2. 2 

. 12

. 25 

.50 

1. 1

Axial ratio

0. 54-0. 60

. 42- 47

. 40

. 43

Remarks. Specimens from locality 3561 differ 

somewhat from specimens from locality 275A, but 

considering the inadequate number of specimens from 

each locality and the several characteristics shared by 

both groups, both collections are included under one 

species. Material from locality 3561 has slightly thinner walls, sharper zooecial bends, and markedly fewer 

acanthopores. Wall thickness may very well have 

been environmentally controlled and the variation in

the number of acanthopores (1.1:1 to 0.50:1 for 

locality 275A and 0.20:1 to 0.18:1 for locality 3561) 

is possible within a species (compare with the well 

represented species, L. lechrium. Otherwise, both 

groups now included in L. leptum are comparable; 

axial ratios for equal growth stages are considered to 

be phylogenetically significant (fig. 27 and p. 79) and 

are thought to indicate that both groups are at the same 

stage of evolutionary development.

L. leptum and L. varium (Duncan) (1939, p. 232, 

pi. 10, figs. 1-3) differ in the microstructure of the 

zooecial w-alls and size of the acanthopores. Z. varium 

has complex w^alls as described and considered diagnostic by Duncan and the acanthopores of the species 

are much larger in diameter, a characteristic that is 

fairly constant for a species.

Types: Holotype USNM 133952 from USGS collection 

3561-SD; figured para types USNM 133953-133955.

Occurrence: Centerfleld limestone member of the Ludlowville shale, USGS 3561-SD, USNM collection 275A, from 

Seneca Lake and the Batavia quadrangle.

Loxophragma lechrium Boardman, n. sp. 

Plate 21, figures 1-4; plate 22, figures 1-6

Diagnosis. Ramose and incrusting Loxophragma 

(branches 3 to 9 mm in diameter) with moderately 

high monticules; nonparallel and cystoidal diaphragms 

occur throughout most zoaria.

Description. Zoaria are ramose, incrusting or a 

combination of both habits. Conspecific overgrowth is 

common, ranging from many thin layers to one thick 

layer. Monticules are generally high and typically 

contain megazooecia with thickened walls, a few mesopores, and enlarged acanthopores that generally cause 

strong inflection of the zooecial walls.

The neanic region exhibits remnants of abandoned 

growing tips indicating partial resorption, and many 

eroded tips covered by subsequent incrusting-ramose 

overgrowth. Zooecial walls range from straight to 

crenulate.

In the ephebic zone, zooecial wall thickness is variable within a zooecium and is largely controlled by 

additions of large numbers of laminae from closely 

and irregularly spaced thick diaphragms. In zooecia 

having a number of thick diaphragms the laminae 

may form a distinguishable zooecial lining as they 

join and become part of the zooecial walls. The 

zooecial walls otherwise are strongly atactotoechid 

(p. 32). Zooecial boundaries are narrow and well 

defined by the intersection of laminae, many of which 

appear continuous across the boundary as seen in 

longitudinal sections. Diaphragms are typically unevenly crowded, nonparallel and planar to irregularly
SYSTEMATIC DESCRIPTIONS 81

curved throughout a zoarium. Closed compartments 

are formed by closely spaced, nonparallel, nearly 

planar diaphragms and a few strongly curved cystoidal diaphragms. Diaphragms are extremely variable in thickness, and many of the thicker diaphragms 

are compound. A few atypical zoaria display some 

intermonticular zooecia that contain planar, parallel, 

and evenly spaced diaphragms. (See Remarks, below). Single rounded nodes or thick stubby spines 

occur on the distal sides of a few thick compound 

diaphragms.

In the tangential view, zooecial apertures are generally polygonal to subpolygonal. Most zooecial walls 

are integrate but a few are narrowly amalgamate in 

a rare zoarium or in exceptionally thick walls of 

megazooecia. Within a zoarium the number of acanthopores is erratic, ranging from very rare to nearly 

one per zooecium. Acanthopores are not restricted 

to the corners of zooecia and are small, causing varying inflection of the zooecial walls. A few mesopores 

are scattered erratically in intermonticular regions 

and many display noticeably thickened walls.

The following table is based on 58 sectioned fragments from 48 zoaria. Sections from more than 110 

zoaria of L. lechrium were examined.

Minimum Maximum

Diameter of zoarium..._________mm.. 2.8 9.2

Width of neanic zone. __._____,do.-.. 1.8 7.3

Zooecial wall thickness--------.do.... .03 .13

Zooecia in 2 mm.._._____..__._____-_ 6 8

Average diameter of zooecia per fragment............------------ mm.. .20 .27

Diameter of megazooecia..---..do.--- ___-__._ .55

Acanthopores per zooecium...._._.__. Very rare . 82

Ontogeny

Width of 

ephebic zone 

Average number of diaphragms (mm) Axial ratio

1 (Ledyard specimen). __._.._._______ 0.7 .75

2.-..-----.......................-- . 6-. 8 . 81-. 85

3---------.--------....-........... .6-1.3 . 70-. 88

4..-..-..--.--.-.-................. .9-1.5 . 60-. 86

5- --------...-.---......-.--._..--- 1.2-2.0 .61-79

Q.................................. 1.3-2.1 . 63-. 72

7.................................. 2.0-2.3 .63-76

8.-.-----.-...--.--................ ]. 6-2. 3 . 52- 68

9..------.--.....-..--........_.._. 1.9 .70

10.-----.-...-.-.--......__........ 1.8 . 61-. 75

12................................. 2.4-2.7 .60-62

14................................. 2.0 .55

15-------.--.-----................. 2.5-3.3 .45-55

20................................. 3.9 .44

22................................. 4.0 .48

Remarks. Specimens displaying parallel, evenly 

spaced diaphragms in the intermonticular zooecia are 

limited to the silty King Ferry shale member at 

Cayuga Lake and the Wanakah shale and Kashong

members at Seneca Lake. Comparable parallelism of 

diaphragms is not consistent in the one incomplete 

zoarium from the King Ferry member for which several longitudinal sections were available. Two of the 

sections displayed parallel evenly spaced diaphragms, 

one was intermediate, and the fourth section contained 

the nonparallel, unevenly crowded diaphragm arrangement typical of the species. Also, in the collections containing zooecia with parallel diaphragms, 

twelve fragmentary zoaria, all represented by single 

longitudinal sections, displayed the parallelism, while 

five zoaria were typically nonparallel and six appeared 

transitional. Zoaria displaying the parallel diaphragms could be considered ecologic variants in response to changing environmental conditions close to 

the eastern limit of trepostome occurrence in the 

Hamilton group. The difference in diaphragm arrangement is not considered constant enough for 

species designation.

The three specimens now placed in L. lechrium from 

the Ledyard member are intermediate between L. leptum and L. lechrium both in stratigraphic position 

and quantitative characteristics (fig. 27) and probably 

could be considered as a linking subspecies in the L. 

leptum-lechrium lineage if more specimens were 

available.

L. lechrium differs from L. spiniferum (Duncan) 

(1939, p. 218, pi. 7, figs. 6, 7) in having a strongly 

atactotoechid wall. The walls of L. spiniferum as 

they appear in the holotype section consist of laminae 

that are somewhat curved as they approach the 

zooecial boundary and the tangential view is amalgamate. Thus, L. spiniferum appears to be transitional between the atactotoechid and leptotrypellid 

walls. Also, the acanthopores of L. spiniferum are 

extremely abundant (1.2 acanthopores per zooecium) 

large, and limited to the zooecial corners.

L. validum (Duncan) (1939, p. 219, pi. 7, figs. 12-14) 

displays smaller more subcircular apertures (average 

0.17 mm in diameter) than L. lechrium and diaphragms that are uniformly thin.

Types: Holotype USNM 133958 from USGS collection 

3518-SD; figured para types USNM 133948-133951, 133956, 

133957, 133959-133961.

Occurrence: Ludlowville shale: Ledyard member of Cooper 

(1930), USGS 3541-SD; Wanakah shale member as used by 

Buehler and Tesmer (in press), USGS-SD 3502, 3505, 3509, 

3511, 3512, 3513, 3514. 3515, 3516, 3518, 3524, 3526, 3532, 3547, 

3555, 3558a, 3565; Tichenor limestone member, USNM collections 250B, 260C; King Ferry shale member of Cooper (1930), 

USGS-SD 3564, 3581. Moscow shale: Kashong member of 

Cooper (1930), USGS-SD 3500, 3558. Localities range from 

Lake Erie to Cayuga Lake.
82 TREPOSTOMATOUS BRYOZOA, HAMILTON GROUP

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LITERATURE CITED 83

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INDEX

acritus, Atactotoechua......................... 8,13,

14,15,16,70,71,72, 73, pi. 17 

aeguabilia, L'ptotrypella.................... 51,53,58

Leptotrypella (Leptotrypella)............. 51

alpenense, Leioclema.......................... 45

alpenensis, Stereotoechus...................... 41

Stigmatella............................... 41

(imphelictn, Leptotrypella................ 15,16,63,64

Leptotrypella (Pycnobasis)-------- 62, 63 pi. 13

amplectens, Leptotrypella..... 6,8,14,16,'40,60, 61,62

Leptotrypella (Leptotrypella)........ 51,60, pi. 12

Monotrypa............................... 2,60

Amplexopara barrandi......................... 53

spinulifera................................ 70

Anomalotoechus tuberatus..................... 40,70

typicus................................... 40,41

asphinctus, Polycylindricus.. 6,11,16,67, 68, 69, pi. 15 

asterica, Leptotrypella.....7, 11, 14, 16, 33, 36, 39, 53,

58, 59, 60, 77 

Leptotrypella (Leptotrypella).... 15, 34, 51, 53,

58, 59, 60, pis. 9, 10 

Astogcnctlc characters....-.-.-......__..... 36,38

Astogcny, controlling variation of zoaria...... 35,36

Atactotocchld wall structure___.......__ 32

4tactotowhus....\2, 14,15, 26, 29, 32, 33, 59, 60, 63, 66,

69, 70, 71, 72, 73, 76, 77, 78, 79 

acritus .. .», 13,14,15,16, 70, 71, 72, pi. 17 

bifoliatus.................................. 70

enrols...................... 14, 35, 70, 73, pi. 18

cartus....--.- 1, 16, 36, 37, 70, 73, pi. 18

pilatus................ 7, 16, 70, 73, 74, pi. 18

casei__...........________.____ 70,75

creber._....____...__.......... 70,73,75

fruticosus..-8, 11, 15, 16, 34, 40, 59, 60, 70, 71, 72,

76, pis. 19, 20 

furcatiis.................................. 59

ft unanensts............................... 70

hystricosus............ ..8,15,16,70,71,72,75, pl.20

inornatus................................. 70,78

limbatus.................................. 70, 75

l>ii........................................ 70

maculosits................................ 70

parallelus..........T, 9,15,16, 70, 71, 72, 74, pi. 17

reticulatus................................ 70

spinuliferus............................... 70

spissus................................ 70,73,75

tnberatus................................. 70

typicus............................. 69,70,73,75

vents..................................... 70

winchelli.................................. 70

Athyris spiriferoides........................... 10,61

uttcmmtuni, Lioclema................_.. 17,47,48

Anlocystis tu.bneformis......................... 6

Aulopora ttibaeformis......................... 60

B

barrundei, Leptolrypella....................... 53

barrandi, Amplewpora........................ 53

Chael.et.es ................................. 51,53

LeptotrypeUa ............................. 51,53

Leptolrypella (Leptotrypella)........... 51, pi. 8

Monticulipora (Hsterotypta)............... 53

Dossier, R. S., and Ulrich, B. 0., quoted..-.. 25-26 

Hatostomella obliqua........................... 50

lifoliatus, Atactotoechus....................... 70

Brachiopocls.._......._.................. 3,9,10

[Italic numbers indicate descriptions]

Page 

brevis, Eridotrypella........................... 51

Bryozoa, growth forms and physical environment.. _ _ _ 8

paleoecology_........................... 8-11

Buffalo axis.......................__.--... 11-12

Calacanthopora............................ 30, 48-44

prima.................................... 43,44

senticosa.. .........__...._. 6,16,17,44, pi. 1

Calcareous mudstonc facies, environment during deposition..___...._..... 10-11

Trcpostomata in.._..................... 10

Callopora punclata............................ 45

cartus, Atactotoechus.............. 14,35,70,73, pi. 18

Atactotoechus cartus..... 7,16, 36,37, 70, 73, pi. 18

pilatus, Atactotoechus....... 7,16, 70, 73, 74, pi. 18

casei, Atactotoechus............................ 70,75

cavernosa, Leptotrypella....................... 51

Centerfleld limestone facies. ..---...--.-..- 9-10 

fauna________._____._.___.__.-____...._. 3,9

stratigraphy...-.-.-.-....... ..._.... 3

Chaetetes barrandi............................. 51, 53

fruticosus........................ 58, 59, 60, 76, 77

furcatus............................. 59,60,76,77

clausus Polycylindricus....... 4,9,15,16,68,69, pi. 16

confertipora, Fistulipora....................... 45

Fistnliporina............................. 45

Thallostigma.............................. 45

confertiporum, Leioclema................... 8,13,16,

17,33, 45, 46,47,48, pi. 3 

Lioclema.................................. 45

Coquinoid concentrations. ------------------- 11

Corals-----...--------.....--.-------.-..-..- 9-10

Coral-bearing limestone facies, environment

and Trepostomata............... 10

creber, Atactotoechus........................ 70,73, 75

Cumings, E. R., quoted..._..._....___ 26,33

Cyphotrypa expanda. 

maculosa........

shearsbyi.........

traversensis......

unica............

D

Dark shale facies, environment and Trcposto 

mata.......-----------.-----.....

decipiens, Fistulipora.........................

Leioclema........... 12, 13, 16, 17, 45, 47, 4

Lioclema. 

Thallostigma..............................

Deep Run member, fauna and stratigraphy...

Dekayia devonica......................... 2,67,

densa, Thallostigma...........................

devonica, Dekayia........................ 2,67,

Leptotrypella.......................... 53,

LeptotrypeUa (Leptotrypella)..............

Stenoporella..............................

devonicus, Polyclindricus......................

digitata, Thallostigma.........................

Discotrypa vera...............................

Duncan, Helen, quoted..... ------------------

Dyoidophragma....................,.... 26,30,

polymorphum.......... 7, 12, 16, 17, 4%, 43,

typicale...................................

9 

47

, pi. 4 

47 

47 

6

68,69 

45

68,69 

57, 58 

51,53 

51 

68 

45 

70 

10

34,4' 

pi. 2 

41

E

Page 

elasmaticum, Leioclema....... 8,16,17, 45,48,49, pi. 4

Environment, adjustment of zoaria to........ 8

dark shale facies....__......... ---- 9-11

Bryozoa as indicators_.....--.-....---.- 8

Eostenopora primiformis...................... 49

villosa.................................... 49

Eridotrypella... ................... ...... 31,50

brevis....--------------------------------- 51

spinifera.................................. 79

valida...................................... 79

sp-- ~ --- 16,50,pl.l

Evolution, trends in Hamilton Trepostomata. 11,12 

expanda, Cyphotrypa.......................... 49

expandus, Trachytoechus...................... 49

Facies.....------.--------------------------- 9-10

Fieldwork. ...... ..................... 2

Fistulipora confertipora....................... 45

decipiens.... ------------------------------ 47

involvens.................................. 45

Fistuliporina confertipora..................... 45

fruticosiis, Atactotoechus... -------------------- 8,

11, 15, 16, 34, 40, 59, 60, 70, 71, 72, 76, 77, 78, 

pis. 19, 20

Chaetetes......................... 58,59,60,76,77

furcata, LeptotrypeUa........... 8,11,15,16,32,53,60

Leptotrypella (Leptotrypella)..... 51, 53, 59, pi. 11 

furcatus, Atactotoechus..-.-....----.-....----. 59

Chaetetes............................ 59,60,76,77

O

Galloway, J. J. and Cumings, E. R., quoted.... 26 

gemmata, Leptotrypella........................ 53

Leptotrypella (Leptotrypella).............. 51

Geographic restrictions, Hamilton Trepostomata....-------.---.------------- 13-14

Glossary...--------------.--.-.---------- 21-23

granulosa, Spinocyrtia.......... --------------- 6,60

H

Hamilton basin, boundary._. .___.. _._... 10-11 

Hamilton Trcpostomata, compared with

Traverse group Trepostomata-... 15 

evolution trends.....................-.-.. 11,12

geographic restrictions............. 13-14

grouping of genera............. ------- 29-33

growth forms. . . - - --- --- 8 

lithofacics.----------------------- - 9

marker beds- . - - 11

morphologic distinctions, trends...-- . 12,15 

phylogcnetic relationships. - ....... 12,13

stratigraphic ranges.-------- ---- 12

sympatric species ....-....-------------- 13

taxonomic problems.._. - - 12,26-29

taxons, criteria for..--------- 12

wallstructure..-.-.- --------------- 26-29

zoaria.--.- --------------------------- 33-35

(Heterotrypa) barrandi, Monticulipora......... 53

howelli, Trachytoechus................ ..--- 49

hunanensis, Atactotoechus----------............ 70

hyalinus, Trachytoechus..........------------- 31

hybrida, Stigmatella........................... 78

hystricosus, Atactotoechus. 8,15,16.70, 71, 72, 75, pi. 20

85
86 INDEX

	Page 

inccmpositum, Leicclema., .................... 45

iwcrustans, Stenopora. ........................ 49

Track yl.oechus-. . ........................... 49

inornatus, A tactotoechus... -------------------- 70,78

involvens, Fistulipora.. ............ ------------ 45

irregularis, Stereotoechus. .. ..-....---.-----.- 41

1C

Kashong member, stratigraphy,

mata-..----..---------. ..,-----.- 7, 10

ICinp Ferry shale member, siltstone facies..... 9

stratigraphy .. ________-----__..---.----.-- 6-7

Trcpos tomata. .........-..-...-.-.-.-.-.. 7,9

kwangsiensis, Lept.ctrypella (Leptctrypella) . . . 51

L 

lechrinm, Loxophragma. ---------------------- 6,

7,8,14,15,16,78,79,80, pi. 21 

Ledyard member, dark shale facies.--.------- 9

stratigraphy, fauna...--------. ----------- 5

Lee, G. AV., quoted..-..---------. ------------ 26,38

/.docZemo. ----------------- 26,30,31,34,44,45,47,49

Leioclema alpenense.......... ................. 45

confer! iporum.... 8, 13, 16, 17, 33, 45, 46, 47, 48, pi. 3

decipiens. ............ 12, 13, 16, 17, 45, 47, 48, pi. 4

elasmaticum.--------..--- 8, 16, 17. 45, . 48, 49, pi. 4

inccmpositum.- --------------------------- 45

micro po r it n» .-.--..----------------.--.---- 45

monroei---- .......................... 2, 45, 46,47

multaculeatum . ........................... 45

passiiabulatum. .....-.--------.----------- 45

segveffadun. .____.___._____._____---------. 45

traoersense..-. ......................... .. 48

Leioclemid wall structure.-.. ------------- ---- 30-31

Lelorhynchus fauna.-------------------------- 9

Leptotrypa nicholsoni. ........................ 41

spin if era .................................. 40

Leptrotrypella- -\2, 13, 14, 15, 17, 26, 27, 28, 29, 32, 34,

51, 52, 53, 54, 55, 59. 62, 63, 71, 79

aeqttabilis. ............................. 51 , 53, 58

(imphelictri-- ........................ 15, 16,63, 6-1

amplectens. --------------- 6,8,14,16,40,60,61,62

asterica. ..... 7. 11 , 14. 16, 33, 36. 39, 53, 58. 59, 60, 77

barrandei --------------------------------- 53

barrandi-. -------------------------------- 51,63

cavernosa --------------------------------- 51

devonica ............................... 53, 57, 58

fitrcata.... .................. 8, 11, IS, 16.32,53,60

gemmata .................................. 53

magnincdi sa. ----------------------------- 53, 58

magniporta ......................... 12, 14.16, 62

mesostena.. ............. 15,52,53,54,55,56,59,64

mesostena.----- 4. 16, 30, 40, 52, 53. 55, 56, 63, 64

provecta. .................. 14,16,52,53,55,56

monilifcrmis . . ---------------------------- 53

multitecta... fi, 7, 8, 14, 15, 16, 33, 39, 40, 52, 53, 54,

55, 56, 57, 59, 63, 64

ohioensis ............................... 51 , 52. 53

pachyph ragma. ...----.----_-.,----------- 16, 63

pellucida.. ------------------------------ 53

polila. ..-------.--_--------.--.------ 7, 16,63,66

noli/aria-. --------------------------------- 51

Inberatn.:..... .................. 6,7, 16,33,63,66

ii/ii dans . ..-.--------.-.-------.----------- 51

varia.-------- ............................. 79

Leptotrupella (Leptotrypella) ------------ 13,5/,60,63

(Leptotrypella) aeqiuibilis.--- -------------- 51

amplectens .................... 51, 60, pi. 12

n»/enco. ....... 15, 34, 51. S3. .58, 59, 60, pis. 9, 10

Imrratidi. ........................... 51, pi. 8

ilevonica. ------- ...................... 51

fiircata... .................... 51,53, 5.9, pi.. 11

<jemma.ta .............................. 51

kwangsiensis..- ----------------------- 51

magninodosa .......................... 51

magniporta.----.-------------... 51,6/,pl. 12

mesostena .......................... 52, 54, 55

mesostena. .......... ...-...- 52.55.pl. 6

pneecta.-. ...:............. 52, 56, pi. 6

Page 

Leptotrypella (Leptotrypella) Continued

moniliformis.......................... 52

multitecta............. 34, 52, 57, 64, pis. 7, 8

ohicensis ---------------------------- 52

parva.-......:........................ 52

pellucida............................... 52

unica................................. 52

Leptotrypella (Pycnobasis).............. 13,15,51,62

(Pycnobasis) amphelicta............ 62,63, pi. 13

pachyphragma..................... 64, pi. 15

polita._------..... ------.-_.-. w>, pis. 13, 14

tuberata.------.......... .... ..... (15, pi. 14

Leptotryppllid wall structure.----------...--- 32

leptum, Loxophragama...-- 4, 14, 15, 16, 79, 81, pi. 21 

Le vann a shale -------------------------------- 3, 9

limbatus, Atactotoechus........................ 70, 75

Lioclema attenuatum....................... 17, 47, 48

confertiporum............................. 45

decipiens. .................................. 47

monroei................................... 45

trover sense............................. 45,47,48

Lithologic units, Hamilton groups..---------- 11

Localities, description..______________________ 18-21

Loxophragma.----------- 12,15.33,63,66,71,78,79,80

lechrium.................................. 6, 7, 8,

14, 15, 16, 78, 79, 80, pis. 21, 22 

leptum.--------------- 4, 14, 15, 16, 79, 81, pi. 21

spiniferum................................ 81

validum- ---------------------------------- 81

varium. ----------------------------------- 80

Ludlowville shale, Centerfleld limestone

member.-....-...--....---.----.. 3-4

Deep Run member....................... 6

King Ferry shale member._--------...--- 6-7

Ledyard member--...-------------------- 5-6

llthofacies.------------------------------- 9-11

Stratigraphy...-. --______---_-_--______._ 3-7

Tichenor limestone member--..-----..--- 6

Trepostomata. --------------------------- 3-7

AVanakah shale member.----------------- 4-5

lui, Atactotoechus----------------------------- 70

M 

maculosa, Cyphotrypa -...--..-......-----.--- 70

maculosus, Atactotoechus---------------------- 70

magninodosa, Leptotrypella -------------------- 53,58

Leptotrypella (Leptotrypella).............. 51

magniporta, Leptctrypella.-------------- 12.14,16,62

Leptotrypella (Leptotrypella)------ 51, 61, pi. 12

Marcellus fauna. See Leiorhynchus fauna. 

Marcellus shale...---------------------------- 3, 9

Marker beds, Hamilton group.--------------- 11

marylandensis, Monticulipora----------- 40, 51, 60, 61

mesostena, Leptotrypella.--.. 15, 52,53, 54, 55, 56, 59, 64

Leptotrypella mesostena..-- 4, 16, 30, 40, 52, 53, 

55, 56, 63, 64, pi. 6

mesostena, Leptrotrypella (Leptrotrypella)- 52, 56,

pi. 6

provecta, Leptotrypella.--- 14, 16, 52, 53, 55, 56,

pi. 6 

micropornm, Leioclema.......---------------- 45

moniliformis, Leptotrypella...----------------- 53

Leptotrypella (Leptotrypella).............. 52

Trhchytoechus-.--------------------------- 4'J

Monotrypa amplectens........................ 2, 60

monroei, Leioclema....................... 2,45, 46,47

Lioclema..--..----------------..------.--- 45

Monticulipora (Hsterotrypa) barrandi.......... 53

marylandensis--- ------------------- 40, 51,60, 61

monticula................................. 41

monticula, Monticulipora..................... 41

monticulatus, Trachytoechus................... 49

monticnlus, Stereotoechus.--------------------- 41

Morphologic trends of 1 [amilton Trepostomata. ..----_-__.__-------_---_-.- 15

Morphology of Trcpostomata.---_--__.------- 23-40

Moscow shale, Kas'~.ong member............. 7

Portland Point member..,..-......-.---- 7

stratigraphy.. __....__......_-_-____...-_. 7-8

Page

Moscow shale Continued

Trepostomata............................ 7-8

AVindom member......................... 7-8

multaculeatum, Leioclema..................... 45

multitecta, Leptotrypella.-.. 6, 7, 8, 14, 15, 16, 33, 39,

40, 52, 53, 54, 55, 56, 57, 59, 63, 64

Leptotrypella (Leptotrypella)....-. 34,52,57,64,

pis. 7, 8

nicholsoni, Leptotrypa. 41

O

obliqua, Hastostomella. ................:....... 50

ohioensis, Leptotrypella...----.........-.... 51,52,53

On togenet ic characters. .-.______..-..-_..____ 36, 38

Orbignyella tenera.- ........................... 41

pachyphragma, Leptotrypella.................. 16,63

Leptotrypella (Pycnobasis)...---..--.. 64, pi. 15 

Paleoecology of Bryozoa.._..____..._..___..__ 8-11

Paleogeography, Hamilton group............. 11-12

Paleschara reticulata.......................... 70

variacella................................. 49

parallelus, Atactotoechus.... 7, 9, 15, 16, 70, 71, 72, 74,

pi. 17 

parva, Leptotrypella (Leptotrypella)........... 52

passitabulatum, Leioclema...-..-..-....---..-. 45

Pelecy pods.-....-...-.--..-......------...... 9

pellucida, Leptotrypella.-...---..---.-....-... 53

Leptotrypella (Leptotrypella)..........-.-- 52

Phylogenetic relationships, Hamilton Trepostomata. -..-..-.....------....... 12, 13

pilatus, Atactotoechus cartus.... 7, 16, 70, 73, 74, pi. 18

Pleurodictyum zone.............. 4,6,10,18,19,20,61

polita, Leptotrypella..-.--.-----...------- 7,16,63,66

Leptotrypella (Pycnobasis).... _-...- 66, pis. 13,14

Polycylindricus.......................... 4,32,40, 67

osphinctus...-........... 6,11,16,67, 68, 69, pi. 15

clausus...................... 4, 9,15,16, 68. pi. 16

denonicus................................. 68

pnlymorphum, Dyoidophragma................ 7,

12,16,12,42,43, pi. 2

Portland Point member, stratigraphy, fauna.- 7 

Previous work....---------------------------- 2

prima, Calacanthopora........................ 43,44

primiformis, Eostenopora...................... 49

pronecta, Leptotrypella (Leptotrypella) ?ne«ostena......................... 52, 56, pi. 6

Leptotrypefla mesostena....... 14,16, 52, 53, 55, 56

ptinctata, Callopora........................... 45

(Pycnobasis) amphelicta, Leptotrypella.-- 62, 63, pi. 13 

Leptotrypella....................... 13,15, 51,62

pachyphragma, Leptotrypella..----.---- 64,pi. 15

polita, Leptotrypella.-.-.-...-..---- 66, pis. 13,14

tuberata, Leptotrypella..-.-..----.----- 65,pi. 14

K

reticulata, Paleschara.---.. 

reticulatus, Atactotoechus.. 

romingeri, Trachytoechus.

Sandstone facies, deposition, fauna.-.---.--... 

segregatnm, Leioclema.........................

senticosa, Calacanthopora....---.-.-- 6,16,17,44

shearsbyi, Cyphotrypa--.......................

Stereotoechus..............................

Siltstone facies, deposition, fauna.... ----------

Skaneatelesformation, stratigraphy, fauna....

solitaria, Leptotrypella........................

spinifera, Eridotrypella........................

Leptotrypa................................

spin iferum, Loxophragma.....................

spiniferus, Stereotoechus.-----------------

Spinocyrtia granulosa....................

spinulifera, Amplexopora.................

spinuliferus, AtactotoechMS......---------

spiriferoides, Athyris.....................

9

45 

1. 1 

41 

41 

U

3,9 

51 

79 

40 

81

40,41

6, 60

70

70

10,61
INDEX 87

Page 

spissus, Atactotoechua...................... 70,73,75

Stach, L. W., quoted..........__....._... 8

Stafford limestone, stratigraphy, fauna........ 3

fltenopora incrustans........ .................. 49

Stenoporella denonica.......................... 51

Stcreotoechid wall structure.................. 30

Stereotoechus............................ 26,31,40,41

alpeveiisii................................ 41

irregularis................................ 41

monticulus................................ 41

shearsbyi.................................. 41

spiniferus................................. 40,41

traversensis............................... 41

tenerus................................... 41

typicns......................... 4,16,40,41, pi. 1

Stigmatella alpensis........................... 41

h ybrida................................... 78

Stratigraphy.......-----------.---.-.--..---- 3-8

Stratigraphic ranges of Hamilton Trepostoinata............................. 12

Strophalosia beds.......-.....--...-.--...-- 4,10,11

snbtilis, Thallostigma.......................... 45

Sympatrlc species In Hamilton Trcpostomata. 13 

Systematic descriptions....................... 40-81

Taxonomy of Trcpostomata............... 12,23-33

tenera, Orbignyella............................ 41

tenerus, Stereotoechns.......................... 41

Thallostigma confertipora...................... 45

decipiens.................................. 47

densa..................................... 45

digitata................................... 45

subtil is.................................... 45

Tichenor limestone member................. 6,9-10

Page 

Time-space relationships in Hamilton Trepostomata........................ 13

Traohytoechld wall structure of Trepostomata...---.-....- ........... 31

Trachytoechus.................... 11,26,29,31,49,50

fxpandus................................. 49

howelli.................................... 49

hyalinus.................................. 31

iucrustans................................ 49

moniliformis.............................. 49

monticulatus.............................. 49

romingeri................................. 49

typicus................................... 49

variacellus.............. 4,9,11,15,16,17,^9, pi. 5

Traverse Trepostomata, Hamilton Trepostomata comparison................. 15

tentative grouping of genera.............. 29-33

traversense, Leioclema......................... 48

Lioclema............................... 45,47,48

traversensis, Cyphotrypa....................... 40

Stereotocchm.............................. 41

Trepostomata, morphology................... 23-40

Trilobite zones.............._.............. 10

tubaeformis, Aulocystis........................ 6

A tUO'pora................................. 60

tuberata, Leptotrypdla.. ........ 6,7,16,33,63,66

Leptotrypella (Pycnobasis)............. 65, pi. 14

tuberatus, Anomalotoechus..................... 40,70

Atactotoechua.............................. 70

typicale, Dyoidophragma...................... 41

typicus, Anomalotoechus...................... 40,41

Atactotoechus....................... 69,70,73.75

Stereotoechus................... 4,16,40,41, pi. 1

Trachytoechus............................. 49

U

Ulrich, E. 0., and Bassler, R. S., quoted.... 25-26 

undans, Leptotrypella......................... 51

unica, Cyphotrypa...............

Leptotrypella (Leptotrypella).

Page

51

52

valida, Eridotrypella. ... 

validum, Loxophragma. 

naria, Leptotrypella..... 

variacella, Paleschara...

................. 79

................. 81

................. 79

................. 49

variacellus, Trachytoechus... 4,9, 11,15, 16, 17,49, pi. 5

varium, Loxophragma. ........................ 80

vera, Discotrypa ... ............................ 70

verus, Atactotoechus. .......................... 70

villosa, Eostenopora. .......................... 49

W

winchelli, Atactotoechus....................... 70

Wall structure of Trepostomata, classification

by................................ 20-33

atactoteochid.. ........................... 32

leioclemid.. ............. ................. 30

leptotrypellid. ........................... 32

previous work ............................ 25-26

stereotoech id ............................. 30

taxonomic problems.. .................... 26-29

trachy toech id . ........................... 31

Wanakah shale............................ 4-5,6,10

Windom member...........--------.-..-.--- 7-8, 10

Z

Xoaria, adjustment to environment........... 8

morphology in taxonomy................. 33-35

ramose growth of......................... 38

variation of, as species criteria............ 35-38

controlled by astogeny_............. 35

Zonules.....-.-.-.-..---.-.-.....-..--.-....-- 11

o
PLATES 1-22
PLATE 1

FIGURE 1. Stereotoechus cf. S. typicus Duncan (p. 41).

la. Longitudinal section of specimen, USNM 133853, X50, containing spherical cysts attached to thin diaphragms.

Centerfield limestone member of Ludlowville shale, collection 275A. 

Ib. Longitudinal section of same specimen, X75, showing stereotoechid wall structure. 

Ic. Tangential section of same specimen, X50, showing amalgamate appearance and megazooecia in bottom half

of figure. 

2-4. Calacanthopora? senticosa Boardman, n. sp. (p. 44).

2a. Tangential section of holotype, USNM 133854, X50, showing amalgamate walls, numerous large acanthopores,

and a few mesopores. Wanakah shale member as used by Buehler and Tesmer (in press) of Ludlowville shale

collection 3502. 

2b. Longitudinal section of holotype, X50, a ramose specimen, the branch containing a hollow axial tube.

3. Tangential section of paratype, USNM 133855, X50, showing mesopores. Wanakah shale member, collection 

3502.

4. Longitudinal section of paratype, USNM 133856, X50, a young zoarium incpisting a crinoid stem. Note the 

configuration of the basal lamina caused by the annulated ridges of the crinoid columnals and the general 

similarity to the configuration of the basal lamina of the holotype specimen, fig. 2b. Wanakah shale member, 

collection 3502. 

5. Eridotrypella sp. (p. 50).

5a. Tangential section of specimen, USNM 133857, X50, showing large mural lacunae filled with opaque material

to produce coarsely granular appearance. Windom member of Moscow shale, collection 3553.

5b. Longitudinal section of same specimen, X50, showing small zooecial angle and wall structure characteristic of 

genus.
GEOLOGICAL SURVEY

7

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PROFESSIONAL PAPER 840 PLATE 1

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STEREOTOECHUS CF. S. TYPICUS, CALACANTHOPORA1, AND ERIDOTRYPELLA
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 2

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6 3c 

DYOIDOPHRAGMA POLYMORPHUM, N. SP.
PLATE 2

FIGURES 1-6. Dyoidophragrna polymorphum Boardman, n. sp. (p. 42).

1. Longitudinal section of paratype, USNM 133859, X50, displaying a zooecial wall inflection at point of attachment of hemiphragm. Wanakah shale member (as used by Buehler and Tesmer, in press) of Ludlowville 

shale, collection 1015.

2. Longitudinal section of paratype, USNM 133860, X 100, showing abnormally crenulated hemiphragms. Kashong member (of Cooper, 1930) of Moscow shale, collection 3500.

3a. Longitudinal section of holotype, USNM 133861, X100, displaying stereotoechid wall structure and the laminated nature of the hemiphragms. King Ferry shale member (of Cooper, 1930) of Ludlowville shale, collection 3564.

3b. Tangential section of holotype, X50, showing amalgamate zooecial walls and mesopores.

3c. Longitudinal view of holotype, X20, showing incrusting relationship of zoarium to crinoid stem with intervening 

layer of mud, abnormally long neanic zone, and conspecific overgrowth.

4. Longitudinal view of paratype, USNM 133862, X100, showing unusually well preserved wall structure and 

laminated hemiphragms. Wanakah shale member, collection 3558a.

5. Tangential section of paratype, USNM 133863, X50, showing amalgamate structure and numerous mesopores. 

Kashong member, collection 3552.

6. Longitudinal view of paratype, USNM 133864, X20, showing the basal lamina in direct contact with the crinoid 

stem and an intervening pocket of mud. Kashong member, collection 3500.

50S925 O 60-
PLATE 3

FinuRES 1 3. Leioclema confertiporum (Hall) (p. 45).

la. Longitudinal view of incrusting specimen, USNM 133865, X20, showing strong wall thickening of monticular 

zooecia. Wanakah shale member (as used by Buehler and Tesmer, in press) of Ludlowville shale, collection 

3558a.

Ib. Longitudinal view of same specimen, X20, displaying fistuliporoid-like vesicular structure in the ncanic zone.

Ic. Tangential section of same specimen, X50, showing thickened zooecial walls in monticule and large central canals 

in some of the acanthopores.

2a. Longitudinal view of identified specimen, USNM 133866, X 10, illustrating morphologic similarity between conspecific overgrowth of subramose form and incrusting zoaria. Note the similar vesicular development in the 

neanic region of fig. Ib. Centerfield limestone member of Ludlowville shale, collection 3528.

2b. External view of part of the zoarium of the same specimen, XI, showing the subramose growth habit.

2c. Longitudinal view of the same specimen, X 5, illustrating the formation of a short branch by a series of overgrowths.

3a. Longitudinal view of lectotype, New York State Museum 734, X50, showing the leioclemid wall structure, some 

vesicular tissue in the neanic zone, and the large central canals of the acanthopores. Hamilton group, Moscow, 

N.Y.

3b. Tangential view of lectotype, X 50, showing amalgamate wall structure, numerous mesopores, and strong zooecial 

wall thickening in lower right corner of figure.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 3

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PLATE 4

FIGURES 1-4. Leiodema decipiens (Hall) (p. 47).

la. Tangential section of holotype, New York State Museum 737, X50, displaying thin zooecial walls and a few

large acanthopores. Hamilton group, York, N.Y.

Ib. Longitudinal view of holotype, X50, revealing a young zoarium covered with a conspecific overgrowth. Note 

large central canals of acanthopores in both primary zoarium and overgrowth.

2. Tangential section of identified specimen, USNM 133867, X50, showing amalgamate wall structure, large acanthopores containing large central canals and numerous mesopores. King Ferry shale member (of Cooper, 

1930) of Ludlowville shale, collection 3582.

3. Longitudinal view of a well developed zoarium, USNM 133868, X20, showing subrectangular compartments in 

the mesopores in the neanic zone. Wanakah shale member (as used by Buehler and Tesmer, in press) of 

Ludlowville shale, collection 3558a.

4. Tangential section of identified specimen, USNM 133869, X50, showing very large acanthopores. Kashong

member (of Cooper, 1930) of Moscow shale, collection 3552. 

5-8. Leiodema elasmaiicum Boardman, n. sp. (p. 48).

5a. Longitudinal section of holotype, USNM 133870, X50, Windom member of Moscow shale, collection 3559. 

5b. Tangential section of holotype, X50, displaying amalgamate walls, mud filled subcircular zooecia, subpolygonal 

mesopores, and no acanthopores.

6. Tangential section of paratype, USNM 133871, X50, showing zooecia and mesopores and no acanthopores. 

Windom member, collection 3559.

7. Longitudinal section of paratype, USNM 133872, X100, displaying the laminated nature of the basal lamina, 

zooecial wall in the neanic and ephebic zone, and the thick diaphragms of the mesopores. Windom member, 

collection 3548.

8. Longitudinal section of paratype, USNM 133873, X75, displaying typical leioclemid wall structure. Windom 

member, collection 3548.
PLATE 5

FIGURES 1-3. Trachytoechus variacellus (Hall) (p. 49).

la. Longitudinal view of holotype, New York State Museum 827, X 10, displaying irregularly undulating zooecial

walls, poorly defined zones of thin and thicker-walled growth generally parallel to the surface of the zoarium,

and the larger megazooecia near center of figure just to the left of club-shaped acanthopore. Hamilton group,

York, N.Y. 

Ib. Tangential section of holotype, X50, showing amalgamate wall structure, large acanthopores roughly polygonal

in cross section, and large megazooecia. 

Ic. Longitudinal section of holotype, X50, displaying a heterophragm in upper left of figure and trachytoechid wall

structure. 

2a. Tangential section of identified specimen, USNM 133874, X20, showing typical development of zooecia and

acanthopores. Centerfield limestone member of Ludlowville shale, collection 3571. 

2b. Longitudinal section of same specimen, X50, showing cystiphragms and cystoidal diaphragms of megazooecia

accompanied by a granular, brown deposit similar to that reported in Ordovician Trepostomata by Cumings

and Galloway, 1915.

2c. Longitudinal section of same specimen, X 20, showing a number of heterophragms. 

2d. Longitudinal section of same specimen, X75, displaying trachytoechid wall structure and a heterophragm with

an even, transparent margin. 

3a. Tangential section of identified specimen, USNM 133875, X50, showing numerous fimbriate heterophragms and

darkened mural lacunae. Centerfield limestome member, collection 3571. 

3b. Longitudinal section of same specimen, X 50, showing heterophragms and a typical acanthopore displaying abrupt

changes in diameter at transverse discontinuities.
GEOLOGICAL SURVEY

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GEOLOGICAL SURVEY

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PROFESSIONAL PAPER 340 PLATE 6

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LEPTOTRYPELLA (LEPTOTRYPELLA) MESOSTENA MESOSTENA, N. SUBSP., 

ANDL. fL.; MESOSTENA PROVECTA, N. SUBSP.
PLATE 6

FIGURES 1-6. LeplolrypeUa (Leptolrypella) mesostena mesoslena Boardman, n. subsp. (p. 55).

1. Longitudinal section of paratype, USNM 133876, X20, illustrating growth stage of 7 to 8 diaphragms. Note 

concentration of mural spines at zooecial bends. Centerfield limestone member of Ludlowville shale, collection 3571.

2. Longitudinal section of paratype, USNM. 133877, X20, displaying growth stage of 6 to 7 diaphragms. Note 

extreme constriction of the diameters of the zooecia in the early ephebic zones and as many as 4 diaphragms 

proximal to the zooecial bends. Centerfield limestone member, collection 3571.

3a. Longitudinal section of holotype, USNM 133878, X20, displaying growth stage of 4 diaphragms. Centerfield 

limestone member, collection 3503.

3b. Tangential section of holotype, X20, sho\ving typical integrate to narrowly amalgamate appearance of zooecial 

walls.

4. Longitudinal section of paratype, USNM 133879, X20, showing growth stage of 2 to 3 diaphragms. Centerfield 

limestone member, collection 3571.

5. Longitudinal section of paratype, USNM 133880, X75, displaying thick zooecial lining and mural spines. Centerfield limestone member, collection 3503.

6. Tangential section of paratype, USNM 133881, X50, showing integrate wall structure and acanthopores inflecting the zooecial walls. Centerfield limestone member, collection 3571. 

7, 8. Leptotrypella (LeplolrypeUa) mesostena provecta Boardman, n. subsp. (p. 56).

7. Longitudinal section of paratype, USNM 133882, X50, showing thick zooecial lining and well defined zone of 

curved laminae, typical leptotrypellid wall structure. Ledyard member (of Cooper, 1930) of Ludlowville 

shale, collection 3541.

8a. Longitudinal section of holotype, USNM 133883, X50, showing thick zooecial lining, mural spines, and conspecific overgrowth with reversed zooecial orientation. Circles in zooecial voids are zooecial spines cut 

transversely. Ledyard member, collection 3541.

Sb. Tangential section of holotype, X50, showing concentration of mesopores in monticule and narrowly amalgamate 

to integrate wall structure. Note mural lacunae in amalgamate zones.

8c. Longitudinal view of holotype, X20, showing constriction of zooecial diameter and 2-4 diaphragms in early 

ephebic zone proximal to the sharp zooecial bends.
PLATE 7

FIGURES 1-4. Leptotrypella (Leptotrypella) multitecta Boardrnan, n. sp. (p. 57).

la. External view of paratype, USNM 133884, XI. Small nodes on branches are monticules, on this zoarium fairly 

high. Arrows indicate positions in the zoarium of corresponding thin sections. Wanakah shale member (as 

used by Buehler and Tesmer, in press) of Ludlowville shale collection 3512.

Ib. Longitudinal section of fragment just below growing tip of same zoarium, X20, showing growth stage of 3 diaphragms.

Ic. Longitudinal section of fragment at base of same zoarium, X20, showing growth stage of 8 to 9 diaphragms.

Id. Tangential section from same zoarium, X20, showing megazooecia of monticule in lower right of figure.

2. Longitudinal view of paratype, USNM 133885, X 10, showing a growing tip with a terminating ephebic zone 

of 2-3 diaphragms. Note abandoned growing tip arching across neanic region that contains just one diaphragm and remnants of zoqecial wall thickening. Wanakah shale member, collection 1017.

3. Longitudinal view of paratype, USNM 133886, X4}<>, showing a zoarium incrusting a Pleurodictyum and also 

developing a ramose growth habit. Wanakah shale member, collection 3565.

4a. Longitudinal view of holotype, USNM 133887, X5, showing origin and typical development of overgrowth. 

Zooecia of primary or supporting branch are extended distally without interruption at origin, or, most proximal 

area of secondary growth. The secondary growth is in all directions, incrusting downward on the primary 

branch with zooecia in reversed orientation (upside down relative to zooecia of primary branch) and a branch 

beyond the primary growing tip that effectively extends the length of the zoarium. Wanakah shale member, 

collection 3524.

4b. Longitudinal view of holotype, X20. Note early ephebic zone without marked constriction of zooecial diameter 

and containing 2-3 diaphragms. Also, zooecial bend is flattened and poorly defined.

4c. Tangential view of holotype, X20, displaying amalgamate zooecial walls and numerous mesopores.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE

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LEPTOTRYPELLA (LEPTOTRYPELLA) MULTITECTA, N. SP.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 8

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LEPTOTRYPELLA (LEPTOTRYPELLA) BARRANDI AND L. (LJ MULTITECTA, N. SP.
PLATE 8

FIGURES 1, 2. Leptotrypella (Leptotrypella) barrandi (Nicholson) (p. 53).

la. Tangential view of identified specimen, USNM 26588, X50, displaying amalgamate wall structure, small acanthopores, and a cluster of three mesopores in monticule. Widder formation, Thedford, Ontario.

Ib. Longitudinal view of same specimen, X75, showing leptotrypellid wall structure consisting of zooecial lining and 

zone of curved laminae.

2. Longitudinal view of identified specimen, USNM 133888, showing abandoned and eroded growing tip and thin,

planar diaphragms. Widder formation, Thedford, Ontario. 

3-8. Leptotrypella (Leptotrypella) multitecta Boardman, n. sp. (p. 57).

3. Longitudinal view of paratype, USNM 133889, X50. Figures 3, 7, and 8 are included on this plate to illustrate 

the extreme morphologic variation common in incrusting zoaria of this species. This zooecia in this figure 

develop abnormally thick diaphragms and lose the leptotrypellid appearance of their walls in this part of the 

zoarium. Wanakah shale member (as used by Buehler and Tesmer, in press), of Ludlowville shale collection 

3511.

4. Longitudinal view of holotype, USNM 133887, X 100, showing relationship of mural spines to laminae of zooecial

lining. Note base of distally placed spines connected with progressively younger laminae. Distal direction

to left of figure. Wanakah shale member, collection 3524. 

5a. Longitudinal section of paratype, USNM 133890, X75, showing abnormally long mural spines. Wanakah shale

member, collection 3519. 

5b. Longitudinal section of same specimen, X50, displaying well preserved leptotrypellid wall structure and an

acanthopore trending at an angle to the zooecia.

6. Tangential section of paratype, USNM 133886, X50, showing mural spines in tangential view. Note acanthopores distributed between zooecial corners and inflecting zooecial walls. Wanakah shale member, collection 

3565.

7. Longitudinal section of paratype, USN M 133891, X50, showing typical appearance of incrusting zooecia of species. 

Note the typical concentration of mural spines near the basal lamina and the early ephebic zone. Wanakah 

shale member, collection 3524.

8. Longitudinal section of paratype, USNM 133892, X50, showing diaphragms of irregular configuration and abnormally thin zooecial walls lacking a zooecial lining. Wanakah shale member, collection 3514.
PLATE 9

FIGURE 1. Leptotrypella (Leptotrypella) asterica Boardman, n. sp. (p. 58).

la. External view of partly reconstructed zoarium of holotype, USNM 133893, X3/10. Numbers in figure indicate 

positions in the zoarium of corresponding thin sections illustrated in the plate. Kashong member (of Cooper, 

1930) of Moscow shale, collection 3543.

Ib. Longitudinal section of holotype taken from growing tip, X20, and illustrating growth stage of 3-5 diaphragms.

Ic. Longitudinal section of holotype taken from position approximately 1/3 down from distal end, X20, showing 

growth stage of 7-9 diaphragms.

Id. Longitudinal section of holotype taken near base of zoarium, X20, showing growth stage of 12-14 diaphragms. 

Note concentration of cysts.

le. Longitudinal view of growing tip of holotype, X3, showing growth stage of approximately 3-5 diaphragms and 

correspondingly narrow ephebic zones. Note the traces of a series of partly resorbed, abandoned growing tips 

arching across neanic zone.

If. Longitudinal view of fragment near base of holotype, X3, illustrating growth stage of approximately 12 diaphragms. Note the rapid increase in width of the neanic zone distally as the branch approaches a normal 

bifurcation. The ephebic zone remains relatively constant in width.

Ig. Tangential section of holotype, X50, showing amalgamate walls typical of the species.

Ih. Longitudinal section of holotype, X 15, showing growth stage of 9-10 diaphragms and a profile view of a "starshaped" prominence.

Ij. Tangential section of holotype, X20, showing "star-shaped" prominence.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 9

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LEPTOTRYPELLA (LEPTOTRYPELLA) ASTERICA, N. SP.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 10

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LEPTOTRYPELLA (LEPTOTRYPELLA) ASTERICA, N. SP.
PLATE 10

FIGURES 1-6. Leplolrypella (Leplolrypella) asterica Boardman, n., sp. (p. 58).

la. Longitudinal view of paratype,.-USNM 133894, X100, showing leptotrypellid wall containing moderately thin

zooecial lining and distinct zone of curved laminae. King Ferry shale member (of Cooper, 1930) of Ludlowville

shale, collection 3572. 

Ib. Longitudinal view of same specimen, X20, showing widely spaced diaphragms typical of variants with thin

zooecial linings. 

Ic. Tangential view of same specimen, X20, displaying broadly amalgamate walls, consistent with leptotrypellid

walls containing wide zones of curved laminae.

2. Longitudinal view of paratype, USNM 133895, X5, showing almost entire length of stunted branch that appears 

as a knob on the zoarium. Note the series of abandoned ephebic zones represented by their proximal parts 

only. Kashong member (of Cooper, 1930) of Moscow shale, collection 3501.

3. Longitudinal view of paratype, USNM 133896, X50, displaying variant with thick zooecial linings and regularly 

and more closely spaced diaphragms. Kashong member, collection 3501.

4. Longitudinal section of holotype, USNM 133893, X50, showing relationship of cysts to diaphragms and zooecia] 

walls. Kashong member, collection 3543.

5. Longitudinal section of paratype, USNM 133897, X10, showing growing tip and proximal position of abandoned 

growing tips in which the amount of resorption was variable. Kashong member, collection 3501.

6a. Longitudinal section of paratype, USNM 133898, X20, illustrating thick zooecial walls and abnormally thick 

diaphragms. Portland Point member (of Cooper, 1930) of Moscow shale, collection 3563.

6b. Tangential section of same specimen, X20, showing thick, broadly amalgamate walls and a monticule marked by 

zooecia with still thicker walls.
PLATE 11

FIGURES 1-6. Lepiotrypella (Leptotrypella) furcata (Hall) (p. 59).

la. Longitudinal view of lectotype, New York State Museum 6187, X50, displaying leptotrypellid walls with little or

no zooecial lining and thin planar diaphragms. Hamilton group, Bellona, New York. 

Ib. Tangential section of lectotype, X50, showing broadly amalgamate zooecial walls that contain mural lacunae,

and abnormally large acanthopores. 

2. Longitudinal section of identified specimen, USNM 133899, X20, illustrating growth stage of 1-3 diaphragms.

Windom member of Moscow shale, collection 3569. 

3a. Tangential section of identified specimen, USNM 133900, X 100, showing broadly amalgamate walls and mural

lacunae. Windom member, collection 3562. 

3b. Tangential section of same specimen, X20. Shows monticule with concentration of mesopores surrounded by

megazooecia, all with thickened walls. 

3c. Longitudinal section of same specimen, X20. Shows growth stage of 7-10 diaphragms, and several subspherical

cysts attached to diaphragms. Note overgrowth with zooecia in reversed orientation.

4. Tangential view of identified specimen, USNM 133901, X20, showing monticule without the central concentration of mesopores. Windom member, collection 3553. 

5a. Longitudinal section of identified specimen, USNM 133902, X 100, showing mural spine and leptotrypellid wall

structure without a distinct zooecial lining. Windom member, collection 3570. 

5b. Longitudinal section of same specimen, X20, illustrating growth stage of 6-8 diaphragms. 

6. Longitudinal view of identified specimen, USNM 133903, X 10, ilustrating a zoarium incrusting upon a crinoid

stem and also forming a branch at right side of figure. Windom member, collection 3569.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 11

6 3b

LEI'TOTRYPELLA (LEPTOTRYPELLA) FVRCATA
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 12

7c

LEPTOTRYPELLA (LEPTOTRYPELLA) AMPLECTENS AND L. fLJ MAGNIPORTA, N. SP.
PLATE 12

FIGURES 1-5. Leptotrypella (Leptotrypella) ampleclens (Grabau) (p. 60).

la. Longitudinal view of ramose part of identified specimen, USNM 133904, X20, showing generally thin walls of 

ephebic zone. Wanakah shale member (as used by Buehler and Tesmer, in press) of Ludlowville shale, collection 3502.

Ib. Tangential view of same specimen, X20, showing aperture of associated corallite in upper part of figure and polygonal zooecia surrounding the corallite.

Ic. Tangential view of same specimen, X50, showing the narrowly amalgamate zooecial walls and small mural spines.

2. External view of identified specimen, USNM 72856, XI, showing the circular corallites surrounded by smaller 

zooecia and the bases of four branches of the coral-bryozoan complex at the anterior end of the supporting 

brachiopod. Wanakah shale member, Hamburg-on-the-Lake, New York.

3. Longitudinal section of identified specimen, USNM 133905, X7.5, cut parallel to the hingeline of the brachiopod. 

Note irregularly undulating zooecial walls, abandoned growing surface with zooecia filled with mud, and thick 

and thinwalled developments in zones generally parallel to the zoarial surface. Wanakah shale member, collection 3519.

4. Longitudinal section through brachiopod and incrusting colony, USNM 133906, X2, illustrating position of incrusting complex on the brachial valve. The figure is oriented on the plate to approximate one possible living 

position of the brachiopod. Wanakah shale member, collection 1017.

5. Tangential section of identified specimen, USNM 133907, X50, showing thickened walls of zooecia and enlarged

acanthopores in a monticule. Wanakah shale member, collection 1017. 

6, 7. Leptotrypella (Leptotrypella) magniporta Boardman, n. sp. (p. 61).

6. Longitudinal section of paratype, USNM 133908, X 50, displaying abnormally thick zooecial walls for the species. 

The wall structure is typically leptotrypellid and includes an appreciable zooecial lining. Windom member 

of Moscow shale, collection 3585.

7ii. Longitudinal section of holotype, USNM 133909, X20. Note close spacing of diaphragms throughout vertical 

ephebic zone. Wanakah shale member, collection 3516.

7b. Tangential section of holotype, X20, showing sharply polygonal cross sections of thinwalled zooecia and the extremely large megazooecia of a monticule.

7c. Tangential section of holotype, X50, showing narrowly amalgamate wall structure of megazooecia.
PLATE 13

FIGURES 1-4. Leptotrypella (Pycnobasis) arnphelicta Boardman, n. sp. (p. 63).

la. Tangential view of holotype, USNM 133910, X20, showing amalgamate wall structure and strongly thickened

zooecial walls in the monticule in lower right corner of figure. Wanakah shale member (as used by Buehler

and Tesmer, in press) of Ludlowville shale, collection 3558a. 

Ib. Longitudinal view of holotype, X 50, showing the leptotrypellid wall structure and thick, strongly curved cystoidal

diaphragms, all compound. 

2a. Longitudinal view of paratype, USNM 133911, X20, displaying crenulated walls in neanic zone, irregular zooecial

growth in high monticule, and an acanthopore extending a considerable distance beyond the zooecia. Wanakah

shale member, collection 3558a. 

2b. Longitudinal view of same specimen, X 50, illustrating leptotrypellid wall structure with a thick zooecial lining.

3. Tangential section of paratype, USNM 133992, X50, showing extreme zooecial wall thickening in a monticule. 

Kashong member (of Cooper, 1930) of Moscow shale, collection 3552.

4. Longitudinal section of paratype, USNM 133912, X50, showing multiple cystoidal diaphragms. Wanakah

shale member, collection 3558a. 

5. Leptotrypella (Pycnobasis) polita Boardman, n. sp. (p. 66).

5a. Longitudinal view of holotype, USNM 133913, X75, showing leptotrypellid wall structure with thick zooecial

linings and narrow zones of curved laminae,, mural spines, and closely spaced, parallel diaphragms. Kashong

member, collection 3558. 

5b. Tangential section of holotype, X20, showing integrate to narrowly amalgamate zooecial walls. Note megazooecia in monticule. 

5c. Tangential section of holotype, X50. The section passes through the concentration of mural spines just distal

to the zooecial bend. Note integrate wall structure.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 13

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LEPTOTRYPELLA (PYCNOBASIS) AMPHELICTA, N. SP., AND L. (P.) POLITA, N.SP.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 14

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LEPTOTRYPELLA (PYCNOBASIS) TUBER ATA, N. SP., AND L. fP.j POLITA, N. SP.
PLATE 14

FinuRES 1, 2. Leplotrypeila (Pycnobasis) tuberata Boardman, n. sp. (p. 65).

la. Longitudinal view of holotype, USNM 133914, X 10, showing raised monticule with strongly thickened zooeeial

walls. Note crinoid columnal and the zooecial growth around it. King Ferry shale member (of Cooper,

1930) of Ludlowville shale, collection 3582. 

Ib. Tangential section of holotype, X50, showing generally integrate wall structure, also the greatly enlarged acanthopores and thickened walls of the zooecia of the monticule in the bottom half of the figure. 

Ic. Longitudinal section of holotype, X50, showing zooecia on the margin of a monticule that contain closely and

irregularly spaced diaphragms, several of them compound. 

Id. Longitudinal section of holotype, X 75, showing a well marked zooecial boundary of abutting laminae and a

zooecial lining determined primarily by the thickness of adjacent diaphragms. 

2a. Longitudinal view of paratype, USNM 133915, X20, showing growth stage of 6-7 diaphragms. Deep Run

member (of Cooper, 1930) of Ludlowville shale, collection 3555a. 

2b. External view of nearly complete zoarium of same paratype, X% showing subramose growth habit, the remains

of a basal expansion, and high monticules on the surface. 

3. Leptolrypclla (Pycnobasis) polita Boardman, n. sp. (p. 66).

3a. Longitudinal view of holotype, USNM 133913, X20, showing growth stage of 11-16 diaphragms. Kashong

member (of Cooper, 1930) of Moscow shale, collection 3558.

3b. Longitudinal view of holotype, X20, showing growth stage of 12-14 diaphragms. 

3c. Longitudinal view of holotype, X20, showing growth stage of 5-7 diaphragms.

508925 O 00-
PLATE 15

FIGURES 1, 2. Polycylindricus asphinchis Boardman, n. sp. (p. 68).

la. Longitudinal section of holotype, USNM 133916, X 50, illustrating the leptotrypellid wall structure that lacks

zooecial lining. Note large laminated acanthopore at top of figure. Wanakah shale member (as used by

Buehler and Tesmer, in press) of Ludlowville shale, collection 3524. 

Ib. Longitudinal section of holotype, X20. Note overgrowth with reversed orientation of zooecia. The zooecia

in upper right corner of figure form the base of a secondary branch projecting at right angles to the primary

branch. 

Ic. Longitudinal section of holotype, X20, showing irregularly crenulated walls of the neanic zone and the budding

of relatively short secondary zooecia from long primary zooecia.

Id. Tangential vie~w of holotype, X20, showing thick, broadly amalgamate walls and the large acanthopores. 

le. Tangential view of holotype, X50, illustrating the laminated acanthopores. 

2. Transverse section of paratype, USNM 133917, X 10, showing the progressive flattening of the zooecia from the

center of the branch outward in the neanic zone. Wanakah shale member, collection 3524. 

3, 4. Leptolrypella (Pycnobasis) pachyphragma Boardman, n. sp. (p. 64).

3a. Longitudinal section of holotype, USNM 133918, X 100, displays irregularly shaped mural spines, thick diaphragms and zooecial lining, and relatively narrow zone of curved laminae. Tichenor limestone member

of Ludlowville shale, collection 3586. 

3b. Tengential section of holotype, X50. Section passes through the concentration of mural spines. Mural lacunae

give speckled appearance to zone of curved laminae. 

3c. Tangential section of holotype, X20. Note integrate appearance of megazooecial walls in monticule at lower

right of figure.

3d. Longitudinal section of holotype, X 20, showing regularly tabulated mesopores and generally thick diaphragms. 

4. Longitudinal section of paratype USNM 133919, X75, showing thick compound diaphragms, thick zooecial

linings, and narrow zones of curved laminae. Wanakah shale member, collection 3555.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 15

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POLYCYLINDR1CUS ASPHINCTUS, N. SP. AND LEPTOTRYPELLA 

(PYCNOBASIS) PACHYPHRAGMA, N. SP.

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GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 16

POLYCYLINDRICUS CLAUSUS, N. SP.
PLATE 16

FIGURES 1-6. Polycylindricus clausus Boardman, n. sp. (p. 68).

la. Longitudinal section of small branch of holotype, USNM 133920, X20, showing normal conspecific overgrowth

separated from the supporting branch by a basal lamination. Windom member of Moscow shale, collection

3553. 

Ib. Longitudinal section of holotype, X50. Note layered structure of cylinder wall and continuation of individual

layers with the zooecial walls of the ephebic zone. 

lc. Longitudinal section of holotype, X20, showing a mesopore, its length contained within the thick-walled part of

the ephebic zone.

Id. Tangential section of holotype, X20, showing petaloid grouping of zooecia around the large acanthopores. 

le. Tangential section of holotype, X50, showing the laminated acanthopores and broadly amalgamate zooecial walls.

2. Longitudinal section of paratype, USNM 133921, X 10. Shows abandoned growing tip that apparently underwent 

little resorption, note large acanthoporc in center of branch at the tip. Section also shows an incrusting overgrowth that gives rise to a secondary branch. Windom member, collection 3553.

3. Transverse section of paratype, USNM 133922, X20, illustrating the progressive flattening of the zooecia from 

the center of the branch outward to the cylinder, fluting of the thickened wall of the cylinder, and the length 

of the acanthopores. Centerfield limestone member of Ludlowville shale, collection 3571.

4. Longitudinal section of paratype, USNM 133923, X20. Illustrates the method of branching that produces 

discordantly small, secondary branches, perpendicular to the supporting stem. Note long acanthopore spine 

of the primary ephebic zone extending well into secondary branch. Centerfield limestone member, collection 

3571.

5. Longitudinal section of paratype, USNM 133924, X20, illustrating secondary growth without the formation of 

a basal lamination, and subsequent formation of a second cylinder and ephebic zone. Centerfield limestone member, collection 3571.

G. Longitudinal section of paratype, USNM 133925, X20, showing elongated, thin-walled zooecial development 

distal to the thickened cylinder. Note also the secondary growth with reversed zooecial orientation. Centerfield limestone member, collection 3571.
PLATE 17

FIGURES 1-5. Atactotoechus acritus Boardman, n. sp. (p. 72).

la. Tangential section of holotype, USNM 133926, X50, showing integrate wall structure with light colored zooecial

boundaries. Centerfield limestone member of Ludlowville shale, collection 3561. 

Ib. Longitudinal section of holotype, X20, showing growth stage of 5-7 diaphragms. 

Ic. Tangential section of holotype, X20, showing monticule in lower left of figure indicated by slightly larger zooecia

with thickened walls.

2. Longitudinal section of paratype, USNM 133927, X20. The part of section displaying zooecia closely approaching A. cartus cartus in general appearance. Ledyard member, collection 3541.

3. Longitudinal section of paratype, USNM 133928, X20, illustrating erratic and non-parailel cystoidal diaphragms. 

Centerfield limestone member, collection 3571.

4. Longitudinal section of paratype, USNM 133929, X5, showing the zoarium incrusting a gastropod and also 

developing a ramose growth habit. Centerfield member, USNM collection 160c, Fellows Falls, Tully quadrangle, New York.

5. Longitudinal section of paratype, USNM 133930, X50, displaying a cystiphragm and atactotoechid wall structure with dark serrated zooecial boundary. Centerfield limestone member, collection 3571. 

6. Atactotoechus parallelus Boardman, n. sp. (p. 74).

6a. Longitudinal section of holotype, USNM 133931, X 100, illustrating atactotoechid wall structure including a dark 

zooecial boundary and an uncommon and very thin zooecial lining that is discontinuous along the zooecium. 

King Ferry shale member (of Cooper, 1930) of Ludlowville shale, collection 3564.

6b. Longitudinal section of holotype, X15, showing growth stage of 25-28 diaphragms in ephebic zone.

6c. Longitudinal section of holotype, X20, showing growth stage of 10-12 diaphragms. Note strong curvature of 

diaphragms of monticular zooecia and parallelism of diaphragms throughout.

6d. Tangential section of holotype, X50, showing integrate appearance and light zooecial boundaries.
PROFESSIONAL PAPER 340 PLATE 17

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6b 6c

ATACTOTOECHUS ACKITUS, N. SP., AND ATACTOTOECHUS PARALLELUS, N. SP.
GEOLOGICAL SURVEY 'KDFKSSIONAL PAPER 340 PLATE 18

ATACTOTOECHUS CARTUS PILATUS. N. SUBSP., AND ATACTOTOECHUS

CARTUS CARTUS, N. SUBSP.
PLATE 18

FIGURES 1-3. Atactotoeclms cartus pilatus Boardman n. subsp. (p. 74).

1. Longitudinal section of paratype, USNM 133932, X50, showing atactotoechid wall structure with zooecial 

boundaries marked by intersection of laminae. Note thick walls and diaphragms. Kashong member (of 

Cooper, 1930) of Moscow shale, collection 3552.

2. Longitudinal section of paratype, USNM 133933, X50, showing well marked zooecial boundaries. Note that 

the thickness of the zooecial walls in the ephebic zone is largely controlled by the thickness of the contributing 

diaphragms. Kashong member, collection 3552.

3a. Tangential section of holotype, USNM 133934, X50, displaying integrate wall structure. Kashong member, 

collection 3552.

3b. Longitudinal section of holotype, X50, showing thick walls and diaphragms. 

4-6. Atactotocchus cartus cartus Boardman, n. subsp. (p. 73).

4a. Longitudinal section of holotype, USNM 133935, X20, showing growth stage of 8-10 diaphragms. Portland 

Point member (of Cooper, 1930) of Moscow shale, collection 3551.

4b. Longitudinal section of holotype, X20, showing growth stage of 7-9 diaphragms. Note strongly curved cystoidal 

diaphragms concentrated in the megazooecia in upper half of figure.

4c. Longitudinal section of holotype, X20, displaying an abandoned growing tip. Note a growth stage of 3-4 

diaphragms below the tip, and 1 diaphragm beyond the tip.

4d. Tangential section of holotype, X20, showing megazooecia of a monticule.

4e. Longitudinal section of holotype, X50, displaying atactotoechid wall structure with a marked zooecial boundary. 

The zooecia are in a monticule; note repeated cystoidal diaphragms.

4f. Tangential section of holotype, X50, showing integrate wall structure and very small acanthopores.

. 5. Longitudinal section of paratype, USNM 133937, X20, showing megazooecia containing planar and parallel

diaphragms. Portland Point member, collection 3551.

6. Tangential section of paratype, USNM 133939, X50. Note only slightly enlarged acanthopores of the megazooecia as compared with the intermonticular zooecia in fig. 4f. Loops in the zooecial voids are curved diaphragms as they appear in tangential section. Portland Point member, collection 3551.
PLATE 19

FIGURES 1-6. Atactotoechus fruticosus (Hall) (p. 76).

la. Tangential section of lectotype, New York State Museum 6182, X50. Note light zooecial boundaries of integrate

walls and the scarcity of acanthopores, Hamilton group, Canandaigua Lake N.Y. 

1 h. Longitudinal section of lectotype, X 50, showing atactotoechid structure of thick zooecial walls. Note zooecial

boundaries are sharply defined and dark in longitudinal sections. 

2a. Longitudinal section of identified specimen, USNM 133940, X20, showing branching part of zoarium. Win do m

member of Moscow shale, collection 3553. 

2b. Longitudinal section from same zoarium, X20, showing incrusting part of zoarium displaying a growth stage of

8-10 diaphragms. The distally located branching part shown in figure 2a has a growth stage of 5-6 diaphragms. 

3a. Tangential section of identified specimen, USNM 133941, X20, showing a monticule with thicker walled megazooecia and several mesopores. Zooecial walls are integrate, a light line marking the zooecial boundaries.

Windom member, collection 3559. 

3b. Longitudinal section of same specimen, X20, showing a growth stage of 23-26 diaphragms.

4. Longitudinal section of identified specimen, USNM 133942, X20, showing growth stage of 4-5 diaphragms and 

an abandoned growing tip that has undergone little or no resorption. Windom member, collection 3553.

5. Longitudinal section of identified specimen, USNM 133943, X20, showing growth stage of 11-13 diaphragms. 

Note irregular growth of zooecia in monticule at bottom of figure. Windom member, collection 3562.

6. Longitudinal section of identified specimen, USNM 133944, X20, showing a growth stage of 6-9 diaphragms. 

The incrusting fistuliporoid bryozoan at the right might have caused the early death of the zooecia in this part 

of the zoarium. Windom member, collection 3579.
GEOLOGICAL Sl-RVKY 

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PROFESSIONAL PAPER 340 PLATE 19

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ATACTOTOECHUS FRUTICOSUS
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 20

4a 4b

ATACTOTOECHUS HYSTRICOSUS, N. SP., AND ATACTOTOECHUS FRUTICOSUS
PLATE 20

FIGURES 1, 2. Atacloloechus hystricosus Boardman, n. sp. (p. 75).

la. Longitudinal section of holotype, USNM 133945, X20. Note repeated cystoidal diaphragms in parallel series,

also alternation of thick and thin-walled growth in the ephebic zone. Windoni member of Moscow shale,

collection 3570.

Ib. Tangential section of holotype, X20, showing a monticule with greatly enlarged megazooecia. 

Ic. Tangential section of holotype, X50, showing the narrowly amalgamate wall structure and the lack of acanthopores. 

2a. Longitudinal section of paratype, USNM 133946, X75, showing atactotoechid wall structure with distinct zooecial

boundaries. Note the minute spines on the distal (left) sides of the diaphragms. Windom member, collection

3570. 

2b. Longitudinal section of same zoarium, X20, cut through a monticule that displays megazooecia containing both

strongly curved cystoidal diaphragms and planar parallel diaphragms. 

2c. Longitudinal section of same zoarium, X20, showing the irregular undulations that are characteristic of the

zooecial walls in the ephebic zone. 

3,4. Atactotoechus fruticosus (Hall) (p. 76).

3. Longitudinal section of identified specimen, USNM 133944, X100, showing atactotoechid wall structure with a

distinct abutting of laminae at the zooecial boundary limited to the early ephebic region. Windom member,

collection 3579. 

4a. Tangential section of identified specimen, USNM 133947, X100, showing integrate wall structure and minute

spines of the diaphragms appearing as small circles in the zooecial void. Windom member, collection 3559. 

4b. Longitudinal section of same specimen, X100, showing the minute spines on the distal side of the cystoidal

diaphragm.

508925 O-60 7
PLATE 21

FIGURES 1-4. Loxophragma lechrium Boardman, n. sp. (p. 80).

1. Longitudinal section of paratype, USNM 133948, X50, displaying atactotoechid wall structure and diaphragms 

typical of the species. Note the similar positions of the thicker diaphragms in each of the zooecia pictured, 

as if each zooid reacted in the same manner to changing environmental conditions. Wanakah shale member 

(as used by Buehler and Tesmer, in press) of Ludlowville shale, collection 3516.

2. Longitudinal section of paratype, USNM 133949, X50, displaying many compound and cystoidal diaphragms. 

Note the sharp definition of the zooecial boundary by the intersection of laminae. Wanakah shale member, 

collection 3558a.

3. Longitudinal section of paratype, USNM 133950, X50, showing a variant with abnormally thick diaphragms, 

most of them compound. Wanakah shale member, collection 3558a.

4. Longitudinal section of paratype, USNM 133951, X50, showing a variant with parallel and evenly spaced diaphragms. Note rounded spine or node on distal side of diaphragm. Wanakah shale member, collection, 3502. 

5-8. Loxophragma Upturn, Boardman, n. sp. (p. 79).

5a. Tangential section of holotype, USNM 133952, X20, showing integrate wall structure, few acanthopores and 

mesopores. Centerfield limestone member of Ludlowville shale, collection 3561.

5b. Longitudinal section of holotype, X20, showing the narrow neanic zone resulting in low axial ratios.

6a. Longitudinal section from paratype, USNM 133953, X50, variant showing atactotoechid wall structure with 

poorly defined zooecial boundaries. Centerfield limestone member, collection 275A.

6b. Tangential section from same paratype, X50, showing small but numerous acanthopores and wall structure that 

has the integrate structure with a light, sharply defined zooecial boundary, but also might be considered amalgamate as there is a discernable nonlaminated zone between the zooecial boundary and the inner darker 

laminated zone.

7. Longitudinal section of paratype, USNM 133954, X50, showing typical atactotoechid wall structure and compound and cystoidal diaphragms typical of the genus. Centerfield limestone member, collection 275A.

8. Longitudinal section of paratype, USNM 133955, X50, showing thin cystoidal diaphragms and atactotoechid 

wall structure. Centerfield limestone member, collection 3561.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 21

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6a

LOXOPHRAGMA LECHRIUM, N. SP., AND LOXOPHRAGMA LEPTUM, N. SP.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 340 PLATE 22

3d 3e

LOXOPHKAGMA LECHRIUM, N. SP.
PLATE 22

FIGURES 1-6. Loxophragma lechrium Boardman, n. sp. (p. 80).

1. Longitudinal section of paratype, USNM 133956, X4, illustrating an incrusting zoarium giving rise to a branch 

at top center. Centerfield limestone member of Ludlowville shale collection 250B.

2. Longitudinal section of paratype, USNM 133957, X5, showing a growing tip with 3-4 diaphragms in the ephebic

/.one and two abandoned growing tips with fewer diaphragms remaining. Wanakah shale member (as used

by Buehler and Tesmer, in press) of Ludlowville shale, collection 3515. 

3a. Tangential section of holotype, USNM 133958, X50, displaying generally integrate wall structure and small

acanthopores that cause some inflection of zooecial walls. Wanakah shale member, collection 3518. 

3b. Tangential section of holotype, X20, showing rare occurrence of zooecia with incomplete walls. Wall laminae

parallel the rounded projection of the incomplete wall indicating incomplete growth rather than a break. 

3c. Longitudinal section of holotype, X20, showing a growth stage of 15-18 diaphragms. 

3d. Longitudinal section of holotype, X20, showing a growth stage of 7-9 diaphragms. 

3e. Longitudinal section of holotype, X20, showing a growth stage of 4 diaphragms.

4. Tangential section of paratype, USNM 133959, X50, illustrating magazooecia of a monticule. The thinness of

the megazooecial walls is caused by the plane of the tangential section passing through the very early ephebic

zone in the megazooecia of the distally projecting monticule, and a later, thicker walled ephebic zone in the

zooecia surrounding the monticule-. See profile view of monticule in figure 6. Wanakah shale member

collection 3558a.

5. Tangential section cf paratype, USNM 133960, X20, showing a monticule in which the megazooecia display 

their maximum wall thickness. King Ferry shale member (of Cooper, 1930) of Ludlowville shale, collection 3564.

6. Longitudinal section of paratype, USNM 133961, X20, showing a growth stage of 10-11 diaphragms and a high 

monticule accentuated by an overgrowth. Kashong member (of Cooper, 1930) of Moscow shale, collection 3558.

U.S. GOVERNMENT PRINTING OFFICE : 1960 O 508925