Mattheva, a Proposed 

New Class of Mollusks 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-B 
., 
Mattheva, a Proposed 

New Class of Mollusks 

By ELLIS L. YOCHELSON 

CONTRIBUTIONS TO PALEONTOLOGY 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-B 

A discussion of the biologic placement of the 

Late Cambrian fossil Matthevia 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1966 
UNITED STATES DEPARTMENT OF THE INTERIOR 

STEWART L. UDALL, Secretary 

GEOLOGICAL SURVEY 

William T. Pecora, Director 

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

Washington, D.C. 20402 - Price 25 cents 
CONTENTS. 

I 

~bstract __________________________________________ _ 

Introduction ______________________________________ _ 

! Acknowledgments ________________ - __ ------------

bccurrence and distribution of Matthevia ______ _____ - _--

fystema tic paleontology _____ -_--------- ---------·-- --

1 Class Mattheva, new class ______________________ _ 

Family Matthevidae Walcott, 1885 ______________ _ 

Page 

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1 

1 

2 

2 

2 

3 

Systematic paleontology-Continued 

Genus Matthevia Walcott, 1885 __________________ _ 

Matthevia variabilis Walcott, 1885 ________________ _ 

Reconstruction of Matthevia ___ -----------------------

Matthevia as the representative of a class of mollusks ___ _ 

Pseudomatthevia _________ ---------------------------

References cited ____ -------------------------------- Index ____________________________________________ _ 

ILLUSTRATIONS 

[Plate follows index] 

1. Photographs of Matthevia. 

1. Sketch of anterior __________________________________________________________________________________ _ 

2. Sketch of posterior __________________________________________________________________________________ _ 

3. Sketches of reconstruction of Matthevia __ ________________________ - --------------------------------------

III 

Page 

B3 

3 

4 

8 

8 

9 

11 

Page 

B3 

3 

6 

CONTRIBUTIONS TO PALEONTOLOGY 

MATTHEVA, A PROPOSED NEW CLASS OF MOLLUSKS 

By ELLIS L. y OCHELSON 

ABSTRACT 

Basic features of the hard parts of JJfa,tthevia Walcott sugest that this fossil is a mollusk. Matthwl'ia, variabUis Walott, first described from the Late Cambrian Hoyt Lime,stone 

ember of Theresa Dolomite near S'aratoga 8prings, N.Y., has 

een found widespread throughout the western conterminous 

nited State~ in rocks of Trempealeau age. Walcott intervreted the preserved part of JJ!atthevia as a conical shell. The 

~enuH is interpreted here as an animal having two hard parts. 

one anterior and one posterior. The presumed anterior pieee 

fS elongate and contains two conspicuous cavities ; the pre-

~umed posterior piece is somewhat narrower and shorter but 

aJso contains two cavities. If this interpretation is correct, 

the hard parts differ markedly from those of other mollusks. 

~ is proposed that JJ!atthevia is the sole known representative 

f an extinct class here given the name Mattheva. 

Pseudomatthevin of Dresbach age is judged to be closely reted to Hyp8eloconus and is provisionally transferred to the 

onoplacophora. 

I INTRODUCTION 

1 M atthevia variabilis Walcott is an enigmatic Campria~ fossil. The original description of the genus and 

fpec1es (vValcott, 1885) is excellent: it emphasizes the 

ilnusual appearance of two cavities separated by a wide 

~eptum within an otherwise massive subconical shell. 

lw!. alcott placed this genus along with 10 others under 

he Pteropoda, doing this with "considerable reservaion," because "They form a group although representaive, in a measure, of the recent Pteropoda, differ in 

pther respects so much that it appears as thouo·h a divi-

~ion of the Gastropoda, equivalent to the P~eropoda, ~night be consistently made to receive them." The iden-

!

. cal. description, but. 'vith better illustrations, was renbhshed the follmnng year (vV alcott, 1886) without 

ny comment about the biological position of the genus 

xcept that it was a pteropod. Walcott (1912) reillusrated the types of Jf a.tthevia with no further comment 

n their systematic position; these illustrations are phoographs, though his drawings of 1886 are almost as 

atisfactory. 

I Miller (1889, p. 392) briefly redefined Matthevia and 

rlaced it within the class Pteropoda. Currently most 

r·orkers on Recent Gastropoda consistently place Pte-

~·opoda as a group of lower rank under the class Gas1 

tropoda. In regard to the Pteropoda as used by him, 

Miller ( 1889, p. 389) stated, "It may well be doubted 

whether or not any of the Palaeozoic fossils belong to 

this order." Other authors of the late 1800's expressed 

similar reservations as to the occurrence of true Pteropoda in Paleozoie strata. The Paleozoic "pteropods" 

were a heterogeneous assemblage; the principal feature 

common to the various genera was the absence of characters that would permit the genera to be placed readily 

into established classes and phyla. 

In the classie textbook by Zittel under the suborder 

Pteropoda, family Hyolithidae, three genera are listed 

in addition to Hyolithes and its synonyms. These are 

Pterotheca, Phragnwtheca, and Jfatthev£a. Although 

there is no discussion, the implication is obvious that 

these three genera are all closely related and are all 

associated with Hyolithes. In every revision and foreign-language edition of this work, the generic name 

is rendered as Jl,/ atthewia, a name which can only be 

treated as an invalid emendation or a typographical 

error. 

l{night (1941, p. 20) declared: "11-fatthevia Walcott, 

1885, a strange and ineomprehensible shell, seems more 

likely to have belonged to some otherwise unknown 

class of the Mollusca or even to emne unknown phylum 

than to the Gastropoda." Two major references on 

American fossils, Grabau and Shimer (1909) and 

Shi1ner and Shrock ( 1944) , do not list M atthevia. 

Flower ( 1954, p. 81) suggested that this genus "is not 

elosely similar to either the hyolithids, the tentaculitids, 

or the gastropods.'' Neither the French "Traite de 

Pah~ontologie" (Piveteau, 1952) nor the Russian handbook ( Orlov, 1958) mention M atthev,ia, though some 

of the other Pnleozoie "pteropods" are discussed and 

classified. Finally, Fisher (1962, p. W128) placed 

Jl,f atthevia as the sole genus within his new suborder 

Matthevina of his new molluscan class Calyptoptomatida. 

ACKNOWLEDGMENTS 

Critical comments of my colleagues over a period of 

8 years have played an important part in shaping my 

Bl 
B2 CONTRIBUTIONS TO PALEONTOLOGY 

thoughts regarding the biologic and taxonomic placement of M atthevia. Though it is obvious that much 

yet remains to be learned about this genus, several associates have encouraged me to put my opinions on record 

so that others may confirm or refute them. 

In particular, I am indebted to A. R. Palmer, U.S. 

Geological Survey, who first called my attention to this 

animal, and to J. F. McAllister, U.S. Geological Survey, 

who at my request collected large quantities of material 

in difficult terrain. V. E. Barnes, Bureau of Economic 

Geology, University of Texas, loaned additional specimens from his collections, as did W. L. Stokes, University of Utah, and Anthony Res0, Tenneco Oil Co., 

Houston, Tex. 

OCCURRENCE AND DISTRIBUTION OF MATTHEVIA 

M atthevia originally was described only from the 

type locality in the Hoyt Limestone quarry, 1 mile 

northwest of Saratoga Springs, N.Y. The matrix is a 

nearly black exceedingly fine grained limestone. Walcott (1885, p. 19) noted that this fossil is associated with 

0 ollenia. Fisher ( 1962a, p. W120) suggested that there 

may be a relationship between the large bodies of Oollen·ia-forming "reefs" and the occurrence of Matthevia. 

He indicated that the form could have been a grazing 

animal, though he did not rule out the possibility that 

specimens observed in the Hoyt may be a lag deposit. 

The Hoyt Limestone Member of the Theresa Dolomite is of Late Cambrian age and is considered to be a 

correlative of the lower part of the Trempealeau, the 

youngest of the three stages of the Upper Cambrian. 

The latest published comprehensive stratigraphie data 

on the New York Cambrian (Fisher, 1962b) indicate 

that the Hoyt Limestone is a local facies of limited 

areal extent and is an eastward-extending tongue of 

the Little Falls Dolomite. Flower (1964, p. 57) indicated the Hoyt as a facies of Whitehall Formation and 

reported "~/ atthevia in local concentrations" within the 

Fort Ann quadrangle in easternmost New York State. 

Since the close of the Second World War, Matthe1-'ia 

has been found to be widespread in the western conterminous United States. The occurrences outside the 

type locality are all of silicified specimens and have 

provided a fairly large series for study. Specimens are 

available from the Wilberns Formation in Texas 

(Cloud and Barnes, 1948, p. 118), the Ajax Formation 

in Utah, the Desert Valley (Reso, 1963) and Nopah 

Formations in Nevada, and the Nopah Formation in 

California. The genus also was identified in the Upper 

Cambrian rocks of the Arbuckle Mountains of Oklahoma by the late Josiah Bridge (W. Ham, written 

commun., 1964) though apparently no specimens were 

obtained. All known occurrences are of Late Cambrian Trempealeau age. Locality details are given by 

Y ochelson, McAllister, and. Reso (1965). Representative specimens are also figured there. 

All the known occurrences of M atthevia are in limestone or dolomite. In the Nevada-California occurrences, the dolomite contains fairly little silt, and the 

acid residues consist almost exclusively of fossil fragments. A. R. Palmer (oral commun., 1964) observed 

little silt in the Utah and Texas matrix. The arrangement of the fossils in partly dissolved blocks shows evidence of sorting. J. F. McAllister searched for algal 

structures associated with M atthevia in eastern California. He reported (written commun., 1963) that at 

one locality in theN opah Formation he observed "cryptozoon -like structures in small masses a foot or two 

across and a few girvanella-like ovoids," and that "certain differences in textures and local accumulations 

seem to indicate some redistribution of carbonate 

debris." 

SYSTEMATIC PALEONTOLOGY 

Class M:ATTHEVA, new class 

Description.-Mollusks having two massive calcareous plates, one anterior and one posterior. 

DiscttB82~on.-The molluscan nature of M atthevia is 

highly probable but is difficult to demonstrate conclusively. Evidence of its basic molluscan character is 

the calcareous shell material of the type lot. The manner in which the shell exfoliates from the steinkern is 

precisely like that of other mollusks broken from limestone and unlike that of other shelled invertebrates. 

This feature is well shown in Walcott's drawings of the 

types. The shell when silicified is spongy in texture, 

also a eharacteristic of most mollusk sheUs. Although 

growth lines, bilateral symmetry, and a thick shell are 

not characters that are the exclusive property of mollusks, they are strongly suggestive of that phylum. 

The subordinal name Matthevina was proposed by 

Fisher (1962a, p. W128) within the order Hyolithida 

Matthew, one of the orders in Fisher's class Calyptoptomatida. Marek and Y ochelson ( 19·64, p. 1675) specifically excluded this suborder in discussing the class 

Hyolitha. Although there are no applicable rules of 

nomenelature, there is considerable precedent for keeping elass-rank names independent of ordinal-rank 

names. The class name given above is based on the 

stem of the typical genus with "a" added as a suffix; 

this scheme is identical with that used by Marek (1963) 

for the class name Hyolitha. 

Should any ordinal subdivisions within the class be 

proposed in the future, Fisher's name Matthevina is 

available. For the present, there is no need to define 

any categories at this level. 
I 

I MATTHEVA, A PROPOSED 

1 Family MATTHEVIDAE Walcott, 1885 

I Description.-Hard parts consisting of two bilatfrally symmetrical subpyramidal plates of calcareous 

faterial, one anterior and one posterior, each of which 

~ontains two cavities. Soft parts unknown in detail, 

~ut presumably including a distinct head and a fairly 

inarrow foot. I 

I Walcott ( 1885, p. 17-18) suggested that the peculiar 

orm that he had named Palaenigm,a might be a correcting link between Oonularia and M atthevia. It is 

1ow generally accepted that Palaenigma was based on 

he partial filling of a conulariid (Sinclair, 1944, p. 87); 

othing seems to link that form to M atthevia. 

Although the question of the systematic position of 

the conulariids is beyond the scope of this paper, it is 

1

of historical interest that many authors between 1850 

l

and 1925 included these forms with the other Paleozoic 

,"pteropods." Repeatedly, these same authors noted 

that this classification was simply a matter of convenience and did not necessarily represent any zoological affinity. Nothing about the conulariids provides 

lany substance to the idea that they should be classified 

I 

as mollusks, a practice common in at least the older 

textbooks. 

I Genus MATTHEVIA Walcott, 1885 

fMatthevia W1alcott, 1885, p. 17, text figs.; Walcott, 1886, p. 224; 

I 

Miller, 1889, p. 392; Walcott, 1912, p. 265; Fisher, 1962, 

p. W128. 

I ~escription.-Hard parts cons~sting of a larger an-

! terwr ( ~) p1ate, flattened on one side, presumed ventral, 

i and a posterior( n plate having less obvious flattening 

on one side. 

Dis(fUSsion.-As only one genus containing one species is known within the class, all descriptions above the 

specific level have been ma:de brief intentionally. If 

other genera are assigned to this class, it will facilitate 

their placement without extensive revisions at every 

taxonomic level. The relatively detailed description 

of the species may incorporate features of higher rank. 

Sketches of the two hard parts are shown in figures 

1 and 2. 

Matthevia variabilis Walcott, 1885 

Plate 1, figures 1-45 

Matthevia variabilis Walcott, 1885, p. 17, figs. 1-6 of p. 20; 

Walcott, 1886, p. 224-225, pl. 32, figs. 1-12; pl. 33, figs. 1, 

la-f; Miller, 1889, p. 392, fig. 647; Lesley, 1889, p. 381-

382 (text figs. from Walcott, 1886); Walcott, 1912, p. 

265, pl. 41; Fisher, 1962a, p. W128, text fig. 72, la-lg. 

D~scription.-Anterior ( ~) plate bilaterally symmetrical, elongate. Sides diverge from anterior point 

at an angle near 25 ° ; sides distinct, nearly vertical, 

turn abruptly into the base and only slightly less 

NEW CLASS OF MOLLUSKS B3 

abruptly into the slightly rounded dorsum. Dorsal surface diverges from ventral surface at an angle near 40° 

and is only slightly arched in profile, the arching most 

apparent near the anterior. Juncture of sides and dorsum a little rounded, the dorsal surface only slightly 

eurved in section. Ventral surface is flattened and is 

mainly in a horizontal plane, except curving downward 

slightly near anterior, and forms almost a right angle 

at juncture with sides. Posterior margin of dorsal surface has a wide U-shaped sinus, the depth of which is 

about one-fourth the total length of the plate. Posterior dorsal margins produced strongly outward and le.ss 

strongly downward from center of dorsal sinus to vertical part of wall, the curvature of margin edge increasing toward this point. At juncture with sides, the 

lateral margins turn through an acute angle, which 

forms the most posterior area of the plate, and proceed 

straight inward and downward nearly to the base; at 

juncture with base, the margins turn slightly to form 

a long, straight, gradual slope extending toward the 

ventral surface about midway along the maximum 

length of the piece, the margin on the ventral surface 

joining in a shallow U-shaped sinus, the base of which is 

FIGURE I.-Presumed anterior piece, approximately three times 

natural size. 

FIGURE 2.-Presumed posterior piece, approximately three 

times natural size. 
B4 CONTRIBUTIONS TO PALEONTOLOGY 

about two-fifths of the distance between anterior and 

posterior of plate. Interior has two cavities: small dorsal cavity, about twiee as wide as high, located just 

below the dorsal surface and separated by a fairly narrow septum from a lower cavity; lower cavity, subcircular in section, occupies nearly half the total height. 

Posterior ( ~) plate bilaterally symmetrical and sides 

diverge from posterior at an angle near 15°; sides 

smoothly and slightly arched throughout their length. 

Maximum width of plate near an oblique plane at right 

angles to plane of symmetry bisecting the sides. Both 

dorsal and ventral surfaces rather well rounded and 

not clearly set off from the sides. Dorsal and ventral 

surfaces diverge at an angle near 30°. Anterior dorsal margin has a wide, shallow sinus, the depth of the 

sinus being less than one-sixth the length of the plate. 

Anterior lateral margins produced strongly outward 

and less strongly downward from eenter of dorsal sinus, 

on either side, to the rounded junction of dorsum and 

sides, for a total of about one-fifth the distance to the 

ventral surface. Margins turn to form an obtuse angle, 

slightly greater than a right angle, on either side of 

piece and proceed gently inward and strongly downward. Margins join at ve,ntral surface with only a 

slight emargination. Interior has a ~mall c.avity wider 

than high, located just below the dorsal surface. Remainder of interior has smooth surfaces, elongate in 

dorsal-ventral plane but otherwise funnel shaped. Cavity mouth about one-fourth the distance from margin 

to posterior tip~ cavity mouth subrectangular, the 

upper edge just along the midline and the lower edge 

slightly more than three-fourths of the total height 

below the smaller dorsal cavity. 

Di1wussion.-The description is based on examination 

of several of Walcott's type specilnens and his illustrations, supplemented by several dozen silicified specimens from California, several dozen from Nevada, 

more than a dozen from Texas, and about half a dozen 

from lJtah. To avoid future nomenelatural problems, 

the original of Walcott's figure 6 of 1885 is here designated lectotype. The remaining specimens of the type 

lot, ail catalogued under USNM 27548, are here designated as paralectotypes. Some of the type lot of 

specimens illustrated in 1886 and 1912 are missing; all 

the 1885 specimens may be available, but there is some 

uncertainty about matching them with the illustrations. Although there may be additional specimens collected by Walcott (the late .T osiah Bridge, oral 

commun., 1952), they have not heen found in the lT.S. 

National Museum collection despite an intensive search 

for them and for the missing types. 

I am taking the broadest view of individual variation 

and consider that all the available material belongs to 

a single species. This seems to be the most meaningful practical approach. Alth0ugh I recognize the 

strong likelihood that specimens collected 2,000 miles 

a part would not belong to the same species, my present 

knowledge provides no way to distinguish between individual variation and interspecific variation. 

Much material is available, but almost all specimens 

are worn or broken. This, coupled with the loss of 

some types and the lack of topotype material, has hampered any meaningful work on the speeific level. Some 

differences have been noted. The specimens from 

Texas have relatively larger cavities than those from 

California; the Utah material may have more strongly 

curved ventral surfaces than specimens from other 

areas. These possible differences are illustrated here 

and in Y ochelson, McAllister, and Reso ( 1965) . 

I do not propose to formalize these possible differences as they may well be the result of selective preservation of extreme examples of variation. The larger 

collections from California and Nevada show a fair 

amount of variability in the shapes of the two parts, 

though not enough to obscure the basic differences between the two forms. Statistical study of individual 

variation in the sizes of the two pieces in each population eventually might be a useful approach. If significant differences could be established, a series of subspecific. names might be applied to the geographically 

separated populations; this approach would satisfy 

both zoological and nomenclatural considerations. 

However, until additional, better preserved material is 

available, I prefer to use only a single species name 

'vithout any trinomial subdivisions. 

RECONSTRUCTION OF MATTHEY/A 

At each locality from which a fair number of specimens are available, the specimens fall into two general 

kinds. This observation was first made by Walcott, 

and it was reinforced when silicified material in quantity "·as first studied. Walcott's figures of 1886 (pl. 

33) definitely show that two growth forms, a wide shell 

and a narrow shell, occur in the type lot. In addition 

to these two forms, Walcott (1885, 1886) described a 

specimen that is lozenge shaped in seetion and has an 

eccentric apex. Although he interpreted this specimen 

as an operculum, I disagree; the outline of the supposed operculum is diseordant with that of other specimens he illustrated. Walcott did not note cavities in 

this supposed operculum. This particular specimen 

has the base broken away, and the shell is exfoliated 

only near the apex. From neither end of the specimen 

could he have had the opportunity to observe any internal cavities. 
MATTHEVA, A PROPOSED NEW CLASS OF MOLLUSKS B5 

It is possible that this supposed operculum may not 

be congeneric with M atthevia. If it were a simple capshaped shell of the monoplacophoran type, it would not 

have contained the two cavities. Unfortunately, this 

particular specimen is missing and the question cannot 

be answered. The presumed operculum is not the only 

point of my disagreement with Walcott's pioneer work. 

The orientation he employed is even more fundamental. 

Walcott illustrated M atthevia with the apex dorsal. 

Thus, in the wider form, there were two ventrally opening cavities separated by a wide septum or internal 

process. Neither of these cavities is particularly large. 

If the narrower piece is oriented in a similar position, 

with the apex dorsal, the septum is so large and both 

cavities are so small that they could have contained only 

a small fraction of the soft parts of the animal. For 

the narrower piece, at least, this orientation seems most 

unlikely, and it is illogical to expect that the two generally similar pieces would have had strikingly different orientations. 

If one accepts the view that the hard parts of lJlatthevia consist of a single piece, then one must also accept 

the fact that at many local1ties two closely related species, or, more likely, bvo closely related genera lived 

near each other. Although this possibility cannot be 

ruled out, it seems unlikely to me. On the assumption 

that the ea vi ties functioned to protect vital soft parts, 

one fonn had a distinct advantage over the other. It 

is difficult to see how this biological situation could 

have occurred. Even if the situation existed, the probability of its occurring on a continent-wide geographic 

range seems so improbable that the notion of two related genera is abandoned. 

An alternative explanation is that the two forms reflect sexual differentiation. A prime difficulty with 

this interpretation is that among living mollusks sexrelated conchological differences are the exception 

rather than the rule. It is unlikely that sexual differences would be pronounced in primitive forms. Reoont 

cephalopods, particularly those with shells reduced or 

absent, show the most obvious sexual differentiation 

within the Mollusca; they are also generally considered 

the most advanced members of the phylum. 

As additional occurrences of M atthevia were found, 

it became increasingly evident that these two pieces are 

best considered as parts of the same biological entity. 

Even though the two plates, or pieces, occur in different numbers at the various localities, this need not interfere with the theory. The pieces have slightly different 

shapes and weights because of the size of the cavities. 

These variations result in different hydrodynamic properties, and if some sorting or reworking of the· hard 

pieces may have occurred, physical processes easily 

793-630 0-66---2 

could account for the difference in relative abundance 

of the two kinds of pieces. Sorting of aptychi from 

cephalopod conchs and opercula from gastropod shells 

are well-known examples of this process. 

My suggestion that M atthevia represents an animal 

having more than one hard part obviously is at considerable variance with the original generic concept. 

Rather than consider this animal as possessing a septum 

separating two cavities, I suggest that it grew calcareous 

"shells" with such geometry that each "shell" contained 

two holes. These holes were not "body cavities," but 

they did contain soft parts of some sort. 

If one accepts the interpretation that M atthevia contained more than one plate, a number of interpretations 

can be made of the biologic significance of these plates. 

Until a specimen with several pieces intact has been 

collected, none of these possibilities can be entirely 

ignored, but some of the more unlikely reconstructions 

can be effectively discarded. 

One must consider briefly the possibility that the 

specimens were part of an internal skeleton rather than 

an external shell. Growth lines, though admittedly 

not an invariable criterion, are strongly suggestive of 

external shells. Except for advanced cephalopods and 

gastropods in which the shell is reduced to a remnant, 

an internal shell is unknown in this phylum. It seems 

unlikely that an internal shell would be a primitive 

character. Evidence from other fields of zoology indicates that a true internal skeleton, at least in a primitive 

animal, seems to be the exclusive province of the 

Deuterostoma. 

Once it is assumed that the shell pieces were external, there are several orientations into which they could 

be placed. Both hard parts haYe in common a plane 

of bilateral symmetry; any reconstruction involving the 

soft parts should also involve such symn1etry. Thus, 

a reconstruction having one sort of plate on one side 

of the animal and another on the other side would 

violate this symmetry. 

If these two plates were dorsal, with the apex upward 

as implied by Walcott (1885, 1886, 1912) and Fisher 

(1962), it would follow that to preserve bilateral symmetry one piece would be behind the other. It is difficult to imagine that the plates could have performed 

any sort of function in this position. Although these 

shell pieces may have been functionless, the large and 

growing volume of literature on functional morphology 

indicates that there are relatively few functionless 

structures in the animal kingdom. Structures having 

apparently neutral survival value do occur among animals, but evidence is increasing that the concept of 

nonadaptive evolution is of littl13 importance. In my 
B6 CONTRIBUTIONS TO PALEONTOLOGY 

view, a plausible function seems inherent in any reconstruction of this extinct form. 

Several other orientations are symmetrical but violate the concept of function. If one piece were dorsal 

and the other ventral, symmetry would be preserved, 

but it is difficult to conceive of soft parts that might fit 

between these two plates. If there were similar parts 

laterally and a different part on the anterior, posterior, 

or both, the hard parts would be arranged symmetrically and there would be bilateral symmetry of the 

soft parts. The resulting animal, however, is so unlikely that it need not be considered further. 

Thus, largely through a process of elimination, one 

is left with a somewhat elongate animal having one 

hard plate anterior and a second plate posterior. This 

also seems most likely to be the correct orientation because it reflects the bilateral symmetry shown by the 

hard parts. If this orientation is correct, the apex is 

not dorsal but is either anterior or posterior. In addition, the ventral aperture of earlier illustrations is not 

ventral but opens centrally. 

The choice remains as to which part is anterior and 

which is posterior. The differences between the two 

do not clearly resolve this particular question. The 

detailed description of the species is based on the supposed orientation outlined in the following discussion,, 

but it is appropriate to remark that other paleontologists have suggested that the anterior and posterior 

designations should be reversed. 

The plate taken to be anterior is more streamlined 

in that it is more elongate, wider~ and lower than the 

second. Further, this plate is characterized by relatively larger cavities than the other. The width seems 

particularly critical as the margins are most likely to 

be broken. By nesting the narrower within the wider 

plate, the margin of each is partly protec-ted. Were 

the margins of this piece anterior, there seems to me 

greater chance that they might have been broken during 

forward movement of the animal. The larger cavities 

might have provided more protection for anterior sense 

organs. Cephalization is a fundamental tendency 

within the mollusks and related phyla. This tendency 

was probably characteristic of even early members of 

the phylum. 

Each hard piece contains only one plane of symmetry. 

If this is taken as a dorsal-ventral plane, then on the 

presumed anterior piece one surface is arched and the 

opposite surface is flattened and curved downward 

slightly toward the anterior apex. If the flattened 

side is oriented as ventral, the larger cavity is below 

the smaller one. The ventral side of the cavity is partly 

open because of the U-shaped sinus. 

The orientation of the second, shorter, narrower, 

and higher plate is somewhat less obvious. It too is a 

flattened asymmetrical pyramid but without any clear 

distinction between dorsal and ventral surfaces, both 

being arched outward. If this piece is oriented with 

the longer surface as ventral, the small cavity is above 

the larger cavity, as in the wider piece. In this orientation, the lateral margins of this piece are slightly 

sinuate and thereby complement the lateral margins of 

the anterior piece which are lobate. This orientation 

of the two pieces is shown in figure 3A. 

Reversing the anterior and posterior pieces as an 

alternative orientation has been tried by placing the 

two parts on a clay model of soft parts. As noted, the 

wider piece is open toward the anterior and the resultant reconstruction is not quite as streamlined as for 

the first orientation. This alternative, less satisfactory 

orientation is shown in figure 30. 

A 

'(:~~~-:~---- --------------------::==~ B 

',, 

'---------------------------=-:::.-::~ 

c 

FIGURE 3.-Possible reconstruction of Matthevia. 

A, Preferred orientation of hard parts. B, 

Same orientation but with hypothetical intermediate plates. a, Alternative orientation of hard parts. Approximately life size. 
MATTHEVA, A PROPOSED NEW CLASS OF MOLLUSKS B7 

One other possible structural element must be discussed. After study of one fragment found before 

1958, I speculated that M atthevia may have been a multiplated animal having peculiar anterior and posterior 

plates and intermediate plates much like those of an 

amphineuran. Having obtained some additional material, I mentioned this possibility ( Y ochelson, 1963). 

Since that time, larger collections have been obtained 

from one locality that yielded presumed intermediate 

plates. After studying these larger collections, I am 

now convinced that the idea of intermediate plates, 

though appealing, is unlikely. The presumed intermediate plates are now interpreted as nothing more 

than selected worn fragments of the anterior plate. 

Almost all degrees of preservation occur, from pieces 

that show slight abrasion of the anterior slope with the 

cavities open at their anterior or posterior ends, to pieces 

that are badly worn. 

Nevertheless, I cannot rule out the possibility that 

intermediate plates might occur. One plausible example of an intermediate is illustrated on plate 1, figures 15-17, so that the reader may judge the validity 

of this hypothesis. An alternative reconstruction, 

having intermediate plates in place, is shown in figure 

3B. The sides of all possible intermediate plates observed are always much shorter than the anterior and 

posterior pieces and are reconstructed accordingly. 

The reconstruction might equally well have been done 

·with the presumed posterior and anterior reversed, but 

there seems little to be gained in laboring this point. 

Additional speculation, that intermediate plates were 

not preserved because they were less heavily calcified 

or perhaps even chitinous during life., is considered very 

tenuous. 

As I envision M attheroia, it was a moderately elongate 

animal. Presumably it crept about the sea bottom on 

its muscular foot; the foot, even if modified, is a common feature of mollusks. The narrowness of the plates 

implies that the body and foot were narrow. The 

streamlined shape of the hard parts would permit moderately rapid currents to flow over them without upsetting the animal's balance. The combination of narrow body and relatively high plates, as well as the absence of intermediate plates to provide flexibility, would 

limit ability to live in areas of strong current and wave 

activity and to cling to rocky surfaces. Despite its 

apparently poor adaptation, it is still easier to imagine 

JJJ atthevia in the role of a clinger than as part of the 

vagrant benthos. 

A head and probably a short neck extended outward 

from beneath the opening in the anterior plate. The 

mantle cavity may have been partly protected by the 

extended flanges on either side of the anterior plate. 

Water may have entered from below and been directed 

upward, a common pattern in mollusks. The dorsal 

gape between anterior and posterior pieces could well 

have resulted from fouled water inhibiting shell growth 

in this zone. The number, position, and kind of gills 

is speculative, as with nearly all fossil mollusks. If 

the gills were partly protected from sediment by being 

within the anterior flange, then there is some likelihood 

that this animal could have moved across a muddy bottom for at least short distances. 

The upper cavity of the anterior plate and the two 

cavities of the posterior plate could have functioned as 

insertions for powerful muscles. It would certainly 

have taken a fairly strong series of muscles to move the 

posterior heavy piece forward, even when it rested on 

the foot. Matthevia probably was mobile though not 

motile. One may further speculate that, in the event 

of danger, the foot and body mass could have been contracted so that a maximum proportion of the soft parts 

would be covered by the hard parts. "When the animal 

was fully or partly extended, there was probably a 

fringe of the mantle around the anterior and posterior 

margins to permit these pieces to continue gnomonic 

growth. 

Speculation as to diet contributes little. Recent 

primitive gastropods are herbivorous, scraping vegetation with a radula. Other recent primitive mollusks, 

including some protobranch pelecypods and the monoplacophoran N eopilina Lemche (Lemche and Wingstrand, 1959, p. 63), are deposit feeders. Some recent 

amphineurans show both food preferences, and a few 

are omnivorous; in general, however, they are herbivores that rasp plants from rocky surfaces. There is 

no clear basis for suggesting either mode of nutrition 

for 111 atthevia.. From the streamlined shape of the 

anterior part alone, it is tempting to consider M atthevia 

as mainly a deposit feeder plowing the bottom, rather 

than as a grazer. On the other hand, the occurrence 

of specimens near algal remains may be more than a coincidence. Perhaps JJ/attheria lived on algal colonies. 

These ideas toward reconstruction of the soft parts 

cover only the more elementary anatomical requirements. Withal, M atthev-ia remains an enigmatic animal. In particular, the weight of the anterior and 

posterior plates must have been a serious problem. Perhaps the animal was oversupplied with calcium carbonate in its diet and these heavy plates were a method 

of removing this mineral from the body. Perhaps, 

alternatively, this weight was one method of solving 

the problems that arise if an elongate shelled animal 

moves from a quiet-water environment into a zone of 

somewhat higher energy. 
B8 CONTRIBUTIONS TO PALEONTOLOGY 

The occurrence of sorted pieces near algal "reefs" in 

two areas suggests moderately active water in the ecological niche where M atthevia may have lived. In a 

sense, M atthevia may have been the ecological precursor 

of the Amphineura, but this attempt to populate a moderately high energy, shallow-water environment was of 

limited success. The experiment seemed almost doomed 

to fail when M atthevia was placed in competition with 

the Amphineura, mollusks more specialized for clinging to curved, rocky surfaces. In contrast to the flattened amphineuran body covered by the flexible multivalved shell, the relatively high, narrow, and heavy end 

pieces of M atthevia seem indeed a poor mechanism for 

maintaining balance against the pull of waves and 

currents. 

MATTHEVIA AS THE REPRESENTATIVE OF A CLASS 

OF MOLLUSKS 

Not only are there no rules of nomenclature to follow 

above the family level, but also there is little accepted 

zoological practice to guide one through problems at 

higher syste,matic levels. My proposal of a new class of 

mollusks, therefore, must carry some explanation. 

The first point at issue is that of placement on the 

phylum level. Although it is theoretically possible for 

a fossil known only from its hard parts to be a representative of an extinct phylum, in actual practice few 

paleontologists have proposed new phyla. I do not 

consider such a course necessary here because the hard 

parts of M atthevia are molluscan, as I have defined this 

term (Yochelson, 1961, p. 164) for paleontolog-ical 

usage. 

If one accepts Walcott's original description of this 

form as an essentially conical shell having two cavities 

separated by an interior septum, there is no place for 

it among the extant classes of mollusks. Its shape is 

distinct from the four classes of univalves. Without 

belaboring the point, the conchological differences between M a.tthevia and Gastropoda, Cephalopoda, and 

Scaphopoda are obvious. Although the Monoplacophora includes, in part, a heterogeneous assemblage, 

some of the less typical members are now better known 

through unpublished work and can be assigned elsewhere. Even if the class remains a heterogeneous one, 

it is beyond the limit of any reasonable taxonomic 

scheme to assign JJf atthevia to Monoplacophora. Although some fossil monoplacophorans approach Matthevia in the external shape, internal details are incompatible with the dual cavity arrangement of this genus. 

Comparison with the bivalved Pelecypoda is preposterous. 

By a process of elimination, comparison with the 

Amphineura remains. If M atthevia is considered a 

univalve, the morphologic uniqueness of the genus is 

evident. It is only if M atthevia is considered to represent an animal with more than one hard part, that 

comJ?arison with the Amphineura is necessary. E-ven 

then, differences are striking. Although amphineuran 

valves are differentiated at the anterior and posterior, 

they in no way resemble the hard pieces of M atthevia. 

Amphineuran valves commonly are wider and much 

lower, have a different shape, are relatively thin rather 

than massive, and, above all, lack the two cavities within 

the hard parts. The pocket in end valves of a few 

forms is ha.rdly comparable. No morphologic feature, 

except the presence of more than one hard piece, can 

relate M atthevia to the Amphineura. 

A more logical alternative is to consider M atthevia a 

representative of a distinct class. In the final analysis, 

probably the only zoologically valid criterion for a 

class is that it be distinct from ·an other classes in the 

phylum. Even with the limitation imposed by the absence of soft parts, ]Jf atthevia seems to fit that criterion. 

PSEUDOMATTHEVIA 

Pseudomatthevia was named because of an apparent 

superficial similarity to M atthevia. However, in the 

original description, Shaw (1956, p. 51) noted that the 

cone-shaped shell lacked the internal septum of Matthe1Jia and was in no way related to that genus. The 

type species, P. conica Shaw, is known from four specimens from the upper DTesbach (Aphelaspw zone) 

Dry Creek Shale near Boulder, Wyo. 

Shaw described this genus as operculate. Para type 

All204c was designated as the operculum. This specimen is a low conical steinkern, broken at the margin. 

As nearly as one can determine, the specimen was originally circular, the apex was central, and there was a 

crenulation in the shell about midway between the 

apex and the margin. Although the remaining specimens are described as slightly ovate, I would consider 

the two paratypes distinctly ovate and the holotype 

possibly so. Thus, the aperture does not have the same 

shape as that of the margin of the supposed operculum. In other features the original description is 

accurate. 

I cannot accept this as an operculate mollusk. In 

my judgment, two genera have been confused. The 

"operculum" is not generically identifiable, though 

in some respects it resembles Palaeacmaea Hall and 

Whitfield, 1872. The holotype and two remaining para types of Pseudomatthevia are closely related to Hypselocon'U8, particularly the less strongly curved Lower 

Ordovician form illustrated by Knight and Y ochelson 

(1958). For the time being, Pseudomatthevia is best 

treated as distinct from Hypseloconus; further study 
MATTHEVA, A PROPOSED NEW CLASS OF MOLLUSKS B9 

of the highly variable Hypseloconus may lead to modification of this opinion. 

A single specimen identified as Pseudomatthevia ~ 

species was described and figured by Shaw (1962, p. 

319, pl. 49, figs. 6, 7) from the lower Dresbach ( Oedaria 

zone) Hungerford Slate of Doll ( 1961), near Highgate Center, Vt. The illustrations of this specimen 

suggest a curved posterior ( ~) slope from which a 

major part of the apex has been broken away. Were 

this apparent curve projected to the presumed apex, 

the resulting form would be quite similar to species 

included within Hypseloconus Berkey. Accordingly, 

I suggest that the unnamed species be transferred to 

that genus. 

REFERENCES CITED 

Cloud, P. E., Jr., and Barnes, V. E., 1948, The Ellenburger 

Group of central Texas: Texas Univ. Pub. 4621, 472 p., 44 

pls. 

Doll, C. G., and otliers, 1961, Centennial geologic map of Vermont: Vermont Geol. Survey, scale 1:250,000. 

Fisher, D. W., 1962a, Small conoidal shells of uncertain affinities, in Moore, R. C., ed., Treatise on invertebrate paleontology. Part W, Miscellanea: New York, Geol. Soc. America and Lawrence, Kans., Univ. Kansas Press, p. W98-

W143. 

---1962b, Correlation of the Cambrian rocks in New York 

State: New York State Mus. and Sci. Service, Geol. Survey 

Map and Chart Ser. 2. 

Flower, R. H., 1954, Oambrian cephalopods,: New Mexico Bur. 

Mines and Mineral Resources Bull. 40, 51 p., 3 pls. 

---1964, The nautiloid order' Ellesmeroceratida (CephaloP>-

oda) : New Mexico Bur . .Mines and Mineral Resources 

Mem. 12, 234 p., 32 pls. 

Grabau, A. W., and Shimer, H. W., 1909, North American index 

fossils: New York, A. G. Seiler and Co., v. 1, 853 p. 

Hall, James, and Whitfield, R. P., 1872, Notice of two new 

species of fossil shells from the Potsdam S'andstone of New 

York: New York State Cabinet, 23d Ann. Rept., adv. print, 

p. 21-23; pub. 1873, 23d Ann. Rept., p. 241-242. 

Knight, J. B., 1941, Paleozoic gastropod genotypes: Geol. Soc. 

America Spec. Paper 32, 510 p., 96 pls. 

Knight, J. B., and Yochelson, E. L., 1958, A reconsideration of 

the relationship of the Monoplacophora and the primitive 

Gastropoda: Malacological Soc. London Proc., v. 33, p. 38-

48, pl. 5. 

Lemche, Henning, and Wingstrand, K. G., 1959, The anatomy 

of NeopiUna galatheae Lemche, 1957 (Mollusca Tryblidiacea) : Galathea Repts., v. 3, p. 9-72, pls. 1-56. 

Lesley, J. P., 1889, A dictionary of the fossils of Pennsylvania 

and neighboring States named in the reports and catalogues of the Survey: Pennsylvania 2d Geol. Survey, Rept. 

P4, 3 v. 

Marek, Ladislav, 1963, New knowledge on the morphology of 

Hyolithes: Sbornfk Geologickych Ved. [Czechoslovakia, 

lTstfednf Ustav Geologicky], Paleontoloiie, fada P, v. 1, 

p. 53-73, pis. 1-4. 

Marek, Ladislav, and Yochelson, E. L., 1964, Paleozoic molluskHyolithes: Science, v. 146, p. 1674-1675. 

Miller, S. A., 1889, North American geology and paleontology 

for the use of amateurs, students and scientists : Cincinnati, Ohio, Western Methodist Book Concern, 664 p. 

Orlov, Y. A., ed., 1958, Mollusca-Cephalopoda, 2; Ammonoidea (Ceratites and Ammonites); Endocochlia; supplement-Coniconchia, Volume 7 of Principles of paleontology-handbook for paleontologists and geologists of the 

U.S.S.R.: Moscow, Govt. Sci. Tech. Press for Literature 

of Geology and Conservation of Mineral Resources, 35·9 p., 

78 pls. [in Russian]. 

Piveteau, Jean, ed., 1952, Brachiopodes, Chetognathes, A.nnelides, Gephyriens, Mollusques, [Volume 2 of] Traite de 

paleontologie : Paris, Masson et Cie, 790 p. 

Reso, Anthony, 1963, A composite columnar section of exposed 

Paleozoic and Cenozoic rocks in the Pahranagat Range, 

Lincoln County, Nevada: Geol. Soc. America Bull., v. 74, 

p. 901-918. 

Shaw, A. B., 1956, A Cambrian ApheZaspi8 fauna from Steel 

Butte, near Boulder, Wyoming: Jour. Paleontology, v. 30, 

p. 48-52, pis. 9-13. 

---1962, Fauna of the Hungerford Slate, Part 8 of Paleontology of northwestern Vermont: Jour. Paleontology, v. 36, 

p. 314-321, pls. 49-50. 

Shimer, H. W., and Shrock, R. R., 1944, Index fossils of North 

America: New York, John Wiley & Sons, 837 p., 303 pis. 

Sinclair, G. W., 1944, Notes on the genera Archaeoconularia 

and Eoconularia: Royal Soc. Canada Trans. ser. 3, v. 38, 

sec. 4, p. 87-95, pl. 1 [1945]. 

Walcott, C. D., 1885, Note on some Paleozoic pteropods: Am. 

Jour. Sci., v. 30, p. 17-21. 

---1886, Second contribution to the studies on the Cambrian faunas of North America: U.S. Geol. Survey Bull. 

30, 369 p., 33 pls. 

---1912, New York Potsdam-Hoyt fauna, in Cambrian geology and paleontology: Smithsonian Misc. CoHn., v. 57, 

no. 9, pt. 2, p. 251-304, pls. 37-49. 

Yochelson, E. L., 1961, Notes on the class Coniconchia: Jour. 

Paleontology, v. 35, p. 162-167. 

---1963, Problems of the early history of the Mollusca: 

Internat. Cong. Zoology, 16th, Washington, D.C., 1963, 

Proc., v. 2, p. 187. 

Yochelson, E. L., McAllister, J. F., and Reso, Anthony, 1965, 

Stratigraphic distribution of the Cambrian mollusk Matthevia Walcott, 1885: U.S. Geol. Survey Prof. Paper 525-B, 

p. B73-B78. 

INDEX 

[Italic numbers indicate major references and descriptions) 

Acknowledgments •• ---------------------------------------------------------- Ajax Formation, Utah _______________________________________________________ _ 

Amphineura ...• -------------------------------------------------------------- Aphel(lspis zone ______________________________________________________________ _ 

Arbuckle Mountains, Okla. _________________________________________________ _ 

Bibliography ________________________________________________________________ _ 

Boulder, Wyo ____ --- ________ -- _ ----------- _______ ---- _______________________ _ 

Page 

B1 

2 

7, 8 

8 

2 

9 

8 

California, Nopah Formation, Matthevia specimens___________________________ 2, 4 Calyptoptomatida____ _ __ _ __ _ ___ _ _ _ _ _ _ _ ___ _ __ _ _ _ _ _ _ _ _ _ __ _ __ _ _ _ _ ___ _ _ ___ _ ___ __ _ 1, 2 

Cedaria zone ___ --- ____ ------__________________________________________________ 9 

Cephalopoda _____ ---_------ ____ --- ____ ------_________________________________ 5, 8 

Collenia. ______________________________ ------ __________________ ------ ____ __ _ __ 2 

conica, Pseudomatthevia. ______________ --- _ ___ __ _ _ __ _ _ _ _ _ __ _ ___ _ __ __ __ ___ _ __ _ __ 8 

Conularia ____ _ --- ___ ------ ________ ------ ____ --- _ _ _ _ _ _ _ _ __ _ _ _ _ _ ___ _ __ _ _ __ _ _ _ _ _ _ 3 

Desert Valley Formation, Nevada ___________________________________________ _ 

Deuterostoma. _ __ ___ _ ___ ___ _ _ _ _ __ _ __ _ _ _ _ _ ___ _ _ _ _ __ _ _ _ __ ___ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ 5 

Distribution, Matthevia__ ___ _ __ _ ___ __ _ _ ___ _ _ _ _ _ _ _ ___ _ _ _ _ _ _ _ __ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ 2 

Dry Creek Shale, Wyoming__________________________________________________ 8 

Flower, R. H., quoted .. ------------------------------------------------------ 1, 2 Fort Ann quadrangle, New York_____________________________________________ 2 

Gastropoda ___________________________ ---------------------------- _________ 1, 5, 7, 8 

Highgate Center, Vt ___________________________________________ ---------------

Hoyt Limestone Member, Theresa Dolomite ________________________________ _ Hungel'ford Slate ____________________________________________________________ _ 

Hyolitha ____ -- ______________________________________________________________ _ 

Hyolithes ___ ------------------------------------------------------------------ Hypseloconus. _______________________________________________________________ _ 

Introduction _______ ---_------_-_-_-_-_-_-_-_-_-_-_- ___ -_______ -___ -- __ ---_-_-_ 

Knight, J. B., quoted _______ ------------c -------------------------------------

Little Falls Dolomite _____________________________________ --------------------

McAllister, J. F., quoted_---------------- __________ ---------- _______________ _ 

9 

2 

9 

2 

1 

8 

Mattheva ___ ------------- ____ ----- ____________________ ----------------------- 1 

Matthevia-------------------------------·-------------------------------- 1, S, 8, pl. 1 

M atthevia-Continued Page 

occurrence and distribution ___________ ---------_------------- __ ----------- Bl 

reconstruction ___ --------------------------------------------------------- 4. 

variabiliB-------------------------------------------------------------- 1, S, pl. 1 

Matthevidae _______________________________ ----------- ___ ------- ___ ---------- S 

Matthevina __ ---------------------------------------------------------------- 1, 2 

Matthewia, invalid name _____________ -------------------------------------_--- 1 

Miller, S. A., quoted._------------------------------------------------------- 1 

Monoplacophora. ________ ------ ____ ------------------------------------------ 8 

Neopilina ____ _____________ -- ___ ----------------------------------------------- 7 

Nevada, Desert Valley and Nopah Formations, Matthevia specimens_________ 2, 4 

New York, Saratoga Springs and Fort Ann quadrangle.---------------------- 2 

Nopah Formation, California and Nevada •• ---------------------------------- 2 

Occurrence, Matthevia. _ ------------------------------------------------------ I 

Oklahoma, Arbuckle Mountains •..• ------------------------------------------ 2 

Palaeacmaea ____ ___________ -- _ --- _ --- _- --------------------------------------- 8 

Palaenigma __ _____________ ------- _ -------------------------------------------- 3 

Pelecypoda _______________________ -------------------------------------------- 7, 8 

Phragmotheca ________________________ ----------------------------------------- 1 

Pseudomatthevia _________ ----------------------------------------------------- 8 

Pseudomatthevia conica ___ ___ -_ ------------------------------------------------ 8 

Pteropoda. ___________________________ -_-------------_-_----------------------

Pterotheca ______ ____________ -- ___ -_- _ ------------------------------------------

Saratoga Springs, N. Y -------------------------------------------------------- 2 

Scaphopoda __ --------- ______ ------------------------------------------------- 8 

Systematic paleontology __________ --_----------------------------------------- I 

Tentaculitids __ ---- _ ----------------------------------------------------------

Texas, Wilberns Formation, Matthevia specimens.---------------------------- 2, 4 

Theresa Dolomite, Hoyt Limestone "Member--------------------------------- 2 

Utah, Ajax Formation, Matthevia specimens---------------------------------- 2, 4 

variabilis, Matthevia.------------------------------------------------------ 1, S, pl. 1 

Vermont, Highgate Center __ ------------------------------------------------- 9 

Walcott, C. D., quoted-------------------------------------------------------

Whitehall Formation __ -- __ ------_--------------------------------------------· 

Wilberns Formation, Texas _______ -- __ ----------------------------------------

Wyoming, Boulder ___________ --- _____ ---------------_-----_------------------

Bll 

'U. S. GOVERNMENT PRINTING OFFICE : 1966 0 - 793-630 

2 

2 

8 
PLATE 1 

FIGURE 1. Left side view of steinkern of posterior piece. USNM 146894; X 17~. From USNM loc. 37b, H mile east of village 

of Salem, Washington County, N.Y. Collected by C. D. Walcott, September 1893 (date is in error). (This 

specimen is in the same tray with others from loc. 76a. In view of the similarity between the specimen and others 

from the Hoyt Limestone Member of Theresa Dolomite (76a) as well as its similarity to Walcott's figure of 1889, 

I am inclined to believe that the wrong locality number was affixed.) 

2-3. "Casts of the chamber of habitation and the inner chambers. The septa are seen at S, 8'." From Walcott, 1886, 

pl. 33, figs. 1 and 1a. Fig. 1 is the original specimen of fig. 2; fig. 3 is probably the original of figs. 4 and 5. The 

figures are oriented as published by Walcott. 

4-5. Anterior and left side views of steinkern of posterior piece. USNM 146895; X 2. From USNM loc. 76a; Railroad quarry, 1 mile north of Saratoga Springs, N.Y. Undoubtedly. from the Hoyt Limestone Member of the 

Theresa Dolomite. 

6-7. Dorsal and interior views of posterior piece. USNM 146896; X 2. From USGS loc. D-1057-CO, near head of 

Lucky Strike Canyon along ridge running eastward from south end of hill6612; coordinates 516,000 ft. E. 570,300 

ft. N., Charleston Park quadrangle, Nevada. Nopah Formation. Collected by R. J. Ross and L. A. Wilson, 

1961. 

8-11. Ventral, dorsal, interior, and right side views of posterior piece. USNM 146897; X 1~. From USGS loc. D-1057-

CO. 

12-14. "End, side and summit views of the most characteristic form, enlarged." From Walcott, 1886, pl. 32, figs. 1-3; 

oriented as published. 

15-17. Dorsal, ventral, and anterior(?) views of worn fragment. USNM 146898; X 2. From USGS loc. 3818-CO, 

isolated hill, 5.5 miles in straight line N. 56° E. from Pyramid Peak, Ryan quadrangle, California. Nopah 

Formation. Collected by J. F. McAllister, 1962. 

18. "Associated operculum, with portions of shell removed." From Walcott, 1886, pl. 32, fig. 4; oriented as published. 

19-22. Dorsal, right side, interior, and ventral views of anterior piece. USNM 146899; X 1~. From USGS loc. D1057-CO. 

23-26. Left side, interior, ventral, and dorsal views of anterior piece. USNM 146900; X 2. From USGS loc. D-1057-CO. 

27-29. "Summit, end, and side views of the conical variety, having a deeply sinuous margin." From Walcott, 1886, pl. 

32, figs. 7-9; oriented as published. 

30-32. Left side, interior, and right side views of posterior piece. USNM 146901; X 1~. From USGS loc. D-1057-CO. 

33-35. Left side, interior, and ventral views of anterior piece. USNM 145317; X 1%. From USGS loc. D-1057-CO. 

[OI).e view of this specimen was illustrated by Yochelson, McAllister, and Reso (1965).] 

36-37. Ventral and left side views of anterior piece; the dorsal surface is broken and the posterior half of the profile is thus 

not correct. USNM 145316; X n~. From USGS loc. 2043-CO, Ajax Dolomite, from above the middle part; 

50-75 feet of dark-gray dolomite that immediately underlies the Garden City Formation. Sec. 27, T. 1 S., R. 

7 W., Timpie quadrangle, Tooele County, Utah. Collected by Dwight E. Arnold, 1955. [One view of this 

specimen was illustrated by Yochelson, McAllister, and Reso (1965).] 

38-39. Ventral and interior view of anterior piece. USNM 145312; X 1%. From USGS loc. 1734-CO, dolomite facies 

of San Saba Member near top of Wilberns Formation. Along west side of a pasture road, 1 mile west of Blanco 

County line and 3,400 feet north of North Grape Creek, Gillespie County, Tex. Collected by L. H. Dixon and 

V. E. Barnes, 1947. [One view of this specimen was illustrated stereoscopically by Yochelson, McAllister, and 

Reso (1965).] 

40-41. Dorsal and interior views of posterior piece. USNM 145313; X H~. From USGS loc. 1734-CO. [One view 

of this specimen was illustrated stereos~opically by Yochelson, McAllister, and Reso (1965).] 

42-45. Ventral, dorsal, left side, and interior views of anterior piece. USNM 146902; X 1~. From USGS loc. D-1057-CO. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 523-B PLATE 1 

2 

s~- ' .~ ?' ' 

--- s' 

' ' .' ~~----- " 

3 

MATTHEVIA