Brachiopoda of the Amsden Formation 

(Mississippian and Pennsylvanian) 

of Wyoming 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-D 

Brachiopoda of the Amsden Formation 

(Mississippian and Pennsylvanian) 

of Wyoming 

By MACKENZIE GORDON, JR. 

THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) 

OF WYOMINC;. 

GEOLOGICAL SUR\'EY PROFESSIONAL PAPER 848-D 

Descriptions and illustrations of 66 sjJecies 

and subsj7ecies of brachiopods, zoith 

discussion of their distribution 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINTON 1975 
UNITED STATES DEPARTMENT OF THE INTERIOR 

GEOLOGICAL SURVEY 

V. E. McKelvey, Director 

Library of Congress Cataloging in Publication Data 

Gordon, Mackenzie, 1913-

Brachiopoda of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming. 

(The Amsden Formation (Mississip.pian and Pennsylvanian) of Wyoming) (Geological Survey professional 

paper ; 848~D) 

Bibliography: p. 

Includes index. 

Supt. of Docs. no.: I 19.16 :848~D 

7. Brachiopoda, Fossil. 2. Paleontology-Carboniferous. 3. Paleontology~Wyoming. I. Title. 

II. Series. III. Series: United States. 

Geological Survey. Professional paper ; 848-D. 

QE796.G67 564' .8'09787 75-619010 

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

Washington, D.C. 20402 

Stock Number 024-001-02635-0 
CONTENTS 

Abstract ----------------------------------------

Introduction -------------------------------------

Previous work -------------------------------

Pres·ent study ----------··--------------------- Acknowledgments ___________________________ _ 

Fossil localities _________________________________ _ 

Composition of the fauna -------------------------

Relation to the Mississippian-Pennsylvanian 

boundary ----------------------------------

Geographic and stratigraphic distribution of the 

brachiopods --------------------------------

Darwin Sandstone Member --------------------

Moffat Trail Limestone Member ---------------

Horseshoe Shale Member ---------------------

Ranchester Limestone Member ----------------

Zonal distribution of the brachiopods ---------------

Analysis of faunal relationships ----------------- Inarticulates ________________________________ _ 

Orthids -------------------------------------

Orthotetoids --------------------------------- Chonetids ------------- ____________ ---------- Productoids _________________________________ _ 

Rhynchonelloids ____ --------------------------

Athyrids ------------------------------------ Spiriferids ---------- _____ -------------------

Retziids and terebratuloids _ -------------------

Interpretation of faunal succession ----------------

Systematic paleontology --------------------------

Superfamily Lingulacea ----------------------

Genus Lingula Bruguiere -----------------

Superfamily Discinacea ----------------------- Genus Orbiculoidea d'Orbigny ____________ _ 

Superfamily Enteletacea ---------------------

Genus Schizophoria King ----------------- Genus Rhipidomella Oehlert_ ______________ _ 

Superfamily Davidsoniacea -------------------

Genus Orthotetina Schellwien --------------

Genus Pulsia Ivanov ---------------------

Genus Schuchertella Girty ----------------

Page 

Dl 

1 

1 

3 

4 

4 

4 

4 

5 

5 

5 

11 

13 

14 

15 

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25 

28 

Systematic paleontology-Continued 

Genus Orthotetes Fischer de Waldheim -----

Genus Derbyia Waagen -------------------

Superfamily Chonetacea ----------------------

Genus Eolissochonetes Hoare --------------

Genus Mesolobus Dunbar and Condra ------

Superfamily Productacea ---------------------

Genus Scoloconcha Gordon ----------------

Genus lnflatia Muir-Wood and Cooper'------

Genus Rugoclostus Easton ----------------

Genus Diaphragmus Girty ----------------

Genus Carlinia Gordon -------------------

Genus Echinoconchus Weller --------------

Genus Flexaria Muir-Wood and Cooper ----

Genus Jwresania Fredericks ---------------

Genus Antiquatonia Miloradovich ----------

Genus Ovatia Muir-Wood and Cooper ------

Genus Lirwproductus Chao ----------------

Superfamily Rhynchonellacea -----------------

Genus Pugnoides Weller ------------------

Superfamily Stenoscismatacea -----------------

Genus Coledium Grant -------------------

Superfamily Athyridacea ---------------------

Genus Cleiothyridina Buckman ------------

Genus Composita Brown ------------------

Superfamily Reticulariacea -------------------

Genus Torynifer Hall and Clarke ----------

Sup·erfamily Spiriferacea ---------------------

Genus Anthracospirifer Lane --------------

Genus Brachythyrina Fredericks ----------

Genus Neospirifer Fredericks -------------

Superfamily Spiriferinacea -------------------

Genus Reticulariina Fredericks ------------

Superfamily Retziacea ------------------------

Genus Eumetria Hall ---------------------

Superfamily Dielasmatacea -------------------

Genus Girtyella Weller -------------------

Incertae sedis -------------------------------

Genus Selenella Hall and Clarke -----------

References cited ---------------------------------

Index -------------------------------------------

ILLUSTRATIONS 

PLATE 

fPiates 1-13 follow index] 

1. Lingula, 0'rbiculoidea, Schizophoria, Rhipidomella, Mesolobus, Eolissochonetes, Schuchertella, and Orthotetes. 

2. O'rthotetina, Pulsia, Schuchertella, Orthotetes, and Derbyia. 

3. lnflatia, Rugoclostus, Echinoconchus, Scoloconcha, Juresania,, and Flexaria. 

III 

Page 

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31 

32 

32 

35 

35 

35 

36 

37 

39 

42 

43 

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45 

46 

49 

51 

53 

53 

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55 

58 

65 

65 

65 

65 

74 

75 

75 

75 

77 

77 

78 

78 

78 

78 

79 

83 
IV CONTENTS 

PLATE 4. Diaphragmus and Carlinia. 

Antiquatonia and Linoproductus. 

Ovatia and Linoproductus. 

5. 

6. 

7. 

8-10. 

11, 12. 

13. 

Coledium, Pugnoides, and Cleiothyridina,. 

Composita. 

A nthracospirifer. 

Anthracospirifer, Brachythyrina, Neospirifer, Eumetria, Girtyella, Reticulariina, and Torynifer. 

P:<.ge 

FIGURE 1. Distribution of Composita in the Amsden Formation __________ _ D18 

TABLE 

2. Distribution of Anthra.cospirifer in the Amsden Formation _____ 19 

3. Profiles of orthotetoid brachiopods in the Amsden Formation ___ 25 

TABLES 

1. Taxonomic relationships and relative abundance of brachiopods 

in the Amsden Formation of Wyoming -------------------

2. Brachiopod fauna of the Amsden Formation of Wyoming ------

3. Che,cklist of brachiopod collections ---------------------------

4. Stratigraphic distribution of Amsden brachiopods equated with 

Page 

D5 

6 

9 

foraminifer zones and coral occurrences ------------------ 15 

5. Goral and brachiopod zones of the Amsden Formation of 

Wyoming ---------------------------------------------- 15 
THE AMSDEN FORl\fATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

BRACHIOPODA OF THE AMSDEN FORMATION 

(MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

By MACKENZIE GoRDoN. JR. 

ABSTRACT 

Brachiopods are the most numerous fossils and biostratigraphically the most useful of the various phyla represented 

in the megafauna of the Amsden Formation of Wyoming. 

The present study is based on more than 4,900 specimens 

from the collections of the U.S. Geologica:! Survey, U.S. Na,.. 

tional Museum, University of Missouri, University of 

Wyoming, and Yal·e University Peabody Museum. The study 

has resulted in the re·cognition of 66 species. and subs·pecies 

of brachiopods belonging in 34 genera. Thes<e species are 

described and illustrated in this report. 

Some of the brachiopods are new, and new names are 

herein proposed for 19 of them. Thes·e are Pulsia delira, 

Orthotetes kaskaskiensis bransonornrn, Infia.tia lovei, Rugoclostus williamsi, Dia.phragmus n.ivosus, Antiquatonia blackwelderi, Ovatia muralis, Linop1·oductus eastoni, Coledimn 

fragmn, Cleiothyridina atrypoides saginata, C. hirsuta darwinensis, Composita sigma, C. poposiensis, Anthracospirifer 

curvilate1·alis brutus, A. rawlinsensis, A. shawi shawi, A. 

s. exoletus, A. weller·i lincolnensis, and Brachythy1·ina 

washakiensis. L·ectotypes are designated for Orthotetir~Ja 

amsdenensis (Branson and Greger), Anthra.cospirifer welleri 

( Brans.on and Greger), Reticulari·ina browni (Branson and 

Greger), and Composita blacku.:elderi C. Branson [ =Ret·iculariina brown·i (Branson and Greger) ] . 

Study of the stratigraphic distribution of the brachioopods 

shows that 41 of the taxa are restricted to the Mississippian 

part of the Amsden, 20 occur only in the Pennsylvanian 

part, and 5 are known to cross the Mississippian-Pennsylvanian boundary. 

The brachiopod distribution demonstrates that the plane 

of the Mississippian-Pennsylvanian boundary, as approximated by t:he biostratigraphic distribution of the Amsden 

faunas, is at an angle to and, in fact, crosses the lithologic 

boundaries separating the members of this formation. In 

western Wyoming the MisSiis:sippian-Pennsylvanian boundary, as delimited by the brachiopods, locally occurs rather 

high in the Ranchester Limestone Member, the uppermost 

of the members of the Amsden; in east-central Wyoming the 

same boundary is somewhere below the base of the Hors·eshoe Shale· Member, which underlies the Ranchester. Interme:diate s.ections show that the west-to-east transgression of 

the Amsden Formation was gradual. 

Brachiopod and, in part, coral assemblages permit the subdivision of the Amsden rocks into sev·eral faunal zones. The 

earliest of these, restricted to western Wyoming, is the 

Caninia coral zone in which Anthracospirife·r curvilateralis 

bn~tus n. subs,p. is perhaps the most characteristic brachiopod. Overlying the Caninia Zone is the Anthracospirifer 

shawi-welleri Zone, predominantly a brachiopod zone, largely 

of rather distinctive anthracospirifers an'd compositas, which 

includes the youngest Mississippian rocks in this region. In 

central Wyoming this :zJone is subdivided into two subzones, 

a lower Carlinia amsdeniana Subzone and an upper Co•mposita poposiensis Subzone. 

The lowest Pennsylvanian zone in western Wyoming is the 

Antiquatonia bla.ckwelderi Zone; it is early Morrowan in age. 

The N eokoninckophyllum hamatilis Zone, named for a coral 

but consisting mainly of brachiopods, is. recognized in the 

Rawlins hills region in southeastern Wyoming and is probably late Morrowan in age. The highest faunal zone, characterized by M esolobus sp. and not given a formal name, 

occurs abo in the Rawlins hills and is Atokan in age. 

INTRODUCTION 

Brachiopods constitute the major element of the 

Amsden megafauna; 66 species and subs pedes have 

been recognized, belonging in 34 genera. These are 

widely but sporadically distributed in limestone, 

sandstone, and ferruginous siltstone beds throughout the formation, with the sole exception of the 

Darwin Sandstone Member, the basal transgressive 

unit of the formation. 

Most of the brachiopod genera in the Amsden are 

those that occur commonly elsewhere in the United 

States in rocks of the same age. Two exceptions to 

this are the orthotetoid genus Puls,ia and the spiriferoid genus Brachythyrina, both of them originally 

described from Upper Carboniferous beds in the 

Moscow basin, U.S.S.R., and now recognized in the 

United States for the first time. Pulsia is represented 

in the Amsden Formation by two species. 

PREVIOUS WORK 

Ever since Darton (1906, p. 31-34) first named 

and described the Amsden Formation, it has been 

Dl 
D2 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

known to contain Pennsylvania brachiopods and 

considered to include beds of both Mississippian and 

Pennsylvania age. Although the Mississippian coral 

upon which Darton based the age of part of the 

Amsden actually came from the Madison Limestone, 

many Mississippian fossils have since been found 

in the formation, including most of the brachiopods. 

The Amsden megafauna is known principally from 

faunal lists made by a variety of paleontologists ; 

these lists have appeared almost exclusively in 

papers dealing with the physical stratigraphy of 

this formation. Only four papers can be said to 

have been oriented toward a study of the paleontology of this formation. 

The first taxonomic work on the fossils of the 

Amsden Formation of Wyoming was by E. B. 

Branson and D. K. Greger (1918). In this paper, 

14 brachiopods that came from the middle part of 

the formation in the Wind River Range were described and illustrated. These are listed below, together with their names as classified in the present 

paper. Omitted from consideration are three other 

brachiopod species, Spirifer shoshonensis Branson 

and Greger, Tetracamera subcuneata (Hall), and 

Chonetes chesterensis Weller, which actually were 

collected from what is now known as the Bull Ridge 

Member of the Madison Limestone (Sando, 1968, 

p. 1855) and are pre-Amsden in age. 

Branson and Greger (1918) 

Orbic;uloidea wyomingensis 

Branson and Greger. 

Orthotetes kaskaskiensis 

(McChesney) . 

Diaph·rag1nus phillipsi 

(Norwood and Pratten). 

Pustula gcnevievensis 

(Weller). 

M eekella amsden ens is 

Branson and Greger. 

Spiriferina browni 

Branson and Greger. 

Spirifer pellaensis (Weller) 

This paJJer 

Orbiculoidea wyomingensis 

Branson and Greger. 

Orthotetes kaskaskiensis 

b·ransonorum n. subsp. 

Carlinia amsdeniana Gordon. 

Flexm·ia sp. 

01·thotetina amsdenensis 

(Branson and Greger). 

Rcticulariina browni 

(Branson and Greger) . 

_Anthracospirifer shawi shawi 

n. subsp. and A. s. exoletus 

n. subsp. 

S. wellm·i Branson and A. weller·i welle-ri (Branson 

Greger. and Greger). 

Martinia n. sp ______________ Composita sigma n. sp.? 

Pugnoides ottumwa (White) _Pugnoides quinqueplecis 

Easton. 

Composita t·rin:uclea (Hall) __ Composita poposiensis n. sp. 

Eumetria verneuiliana (Hall) _Eumetria. sulcata Burk. 

Cleiothyridina hirsuta (Hall) _Cleiothyrid1'nn aff. C. elegwns 

Girty. 

Schizophm·ia swallo·vi (Hall) ?_Schizophorin depressa Easton. 

Branson and Greger (1918, p. 312) concluded that 

the fauna is Late Mississippian in age and should 

be correlated with that of the St. Genevieve Limestone (upper Meramecian) of the Mississippi River 

valley. 

Eight Amsden brachiopods, six of them regarded 

as new, were described and figured by C. C. Branson (1937, p. 655-657, pl. 89). They are from the 

same general area in the Wind River Range as those 

of Branson and Greger. Four of these new specie·s 

were based on tiny juvenile shells, at least part of 

which came from the residue of washed material 

from which Morey (1935) described the ostracodes. 

These juveniles are marked with an asterisk ( *) in 

the list below. They have been identified as young 

specimens of the species shown in the right-hand 

column. 

C. C. Brctnson (1937) 'l'his paper 

0Tbiculoidea wyomingensis Orbiculoidea wyomingensis 

Branson and Greger. Branson and Greger. 

*Rhipidmnella gregeTi C. A nthracospirifer welleri wellBranson. eri (Branson and Greger). 

*Rhipidomella gTege1·i C. GiTtyella cf. G. indianensis 

Branson (one para type). Girty. 

*Streptm·hynchus poposiensis Schuchertella poposiensis 

C. Branson. (C. Branson). 

Chonetes suttoni C. Branson __ Species inquirenda. 

Linoproductus croneisi Ovatia croneisi (C. Branson). 

C. Branson. 

*Selenella? 1valte1·i C. 

Branson ( holotype). 

*Selenella? walteri C. 

Branson (two pai'Iatypes). 

?Girtyella indianensis 

(Girty). 

*Composita blackwelderi C. 

Branson. 

Sp·ecies inquirenda. 

Pugnoides qninqueplecis 

Easton. 

Girtyella cf. G. indianensis 

(Girty). 

Reticulariina browni 

(Branson and Greger) . 

C. C. Branson (1937, p. 650-653), like E. B. Branson and Greger before him, regarded this fauna as 

St. Genevieve in age, but he included it in his Sacajawea Formation (Branson, 1936), which he had 

separated from the main part of the Amsden Formation because, he pointed out, other geologists had 

recognized fossils of Pennsylvanian age at several 

localities in the upper beds of the Amsden. Branson's type section of the Sacajawea Formation on 

Bull Lake Creek, however, ·consisted entirely of 

limestone belonging in the upper part of the Madison 

Limestone and is early Meramecian in age. These 

beds have been renamed Bull Ridge Member of the 

Madison Limestone by Sando. 

Burk (1954) described and figured brachiopods 

collected by C. A. Biggs from the Amsden of the 

Wind River Range. Bigg's specimens came from 

Beaver Creek, South Pass, Cherry Creek, and Horse 

Creek, all in Fremont County. These fossils are from 

the Horseshoe Shale Member of the Amsden Formation. Burk's. identification are listed below with 

the identifications of the same fossils as revised by 
BRACHIOPODA OF THE AMSDEN FORMATION D3 

the present study. Burk (1954, p. 5) concluded that 

all the fossiliferous beds of the Amsden Formation 

are Pennsylvanian in age. This conclusion was foregone, seeing that he identified his fossils largely as 

Pennsylvanian species, including some of the same 

forms that E. B. Branson and Greger and C. C. 

Branson had previously determined as Mississippian 

species. 

C. A. Burk (1954) This paper 

Lingulodiscina sp ___________ Qrbiculoidea sp. A. 

Orthotetes? sp ______________ Qrthotetes kaskaskiensis 

Dictyoclostus portlockianus 

(Norwood and Pratten). 

bransonorum n. subs.p? 

lnflatia lovei n. sp. 

Linoproductus prattenianus Ovatia muralis n. sp.? 

(Norwood and Pra tten) . 

Cancrinella boonensis 

(Swallow). 

M arginifera muricatina 

Dunbar and Condra. 

Ovatia c,roneisi (C. Branson). 

Ca'rlinia, amsdeniana Gordon. 

Marginifera sp -------------Productoid, gen. and sp. indet. 

Spirifer opimus Hall ________ Anthracospin'jer shawi 

exoletus n. subs.p. 

Spirifer opimus Hall (one Anthracospirifer· welleri wellspecimen). eri (Branson and Gre~er). 

Spirifer· s.p -----------------Anthracospirifer· shawi 

Composita subtUita var. 

subtilita (Hall). 

Composita subtilita var. 

ovata Mather. 

CMnposita subtilita var. 

trinuclea (Hall). 

exoletus n. suhsp. 

Composita poposiensis n. S'P· 

and C. sulcata Weller. 

Composita sulcata Weller. 

and C. poposiens1's n. sp. 

Composita poposiensis n. sp. 

Composita sp _______________ Composita sp. 

Cleiothyridina sp ___________ Composita poposiensis n. sp. 

(juvenile) and Cleiothyridina hirsuta darwinensis n. 

suhsp. 

Eumetr·ia sulcata Burk ______ Ewnetn~a sulcata Burk 

W ellerella osagensis 

(Swallow). 

Pugnoides quinqueplecis 

Easton. 

The following year, Shaw and Bell (1955) repGrted on six collections that Bell had collected in 

situ by trenching the section at Cherry Creek. 

They listed the species from these collections on a 

chart showing their stratigraphic occurrences and 

concluded that Mississippian fossils are present as 

much as 48 feet above the base of the formation, and 

Pennsylvanian fossils are present 63 feet above the 

base. No descriptive taxonomic work accompanied 

this study. 

Shaw (1955) also restudied Burk's fossils and 

those of other students at the University of Wyoming and concluded that a lower Spirifer wellet·i 

fauna of Mississippian age could be recognized in 

several sections, as well as a higher Spirifer 

"opimus" fauna of Pennsylvanian age. 

A recent descriptive work with a direct bearing 

on the faunas of the Amsden Formation is the study 

by Easton (1962) of the Carboniferous formations 

and faunas of central Montana. A few fossils that 

he described from the Heath Formation of Montana 

have been recognized during the present study in 

the Mississippian part of the Amsden Formation of 

Wyoming, and several species from the Cameron 

Creek Member of the Tyler Formation and Alaska 

Bench Limestone of Montana have turned up in the 

Pennsylvanian part of the Amsden. Easton (1962, p. 

14-16) believed all three of these Montana stratigraphic units to be Mississippian in age. More recently, however, Maughan and Roberts (1967) have 

insisted on a Pennsylvanian age for the upper two 

units. 

After this manuscript was completed, an excellent work on Pennsylvanian brachiopods was published by Sutherland and Harlow (1974, Pennsylvanian brachiopods and biostratigraphy in southern 

Sangre de Cristo Mountains, New Mexico: New 

Mexico Bur. Mines and Mineral Resources, Mem. 27, 

1973 p., 18 pls., 51 figs., 30 photos). Their designation of a lectotype for Spit·iferina spinosa var. 

campestris White has led me to the present treat 

ment of S. campestris and S. gonionota Meek as different species belonging in different genera, in the 

discussion of Reticulariina browni (Branson and 

Greger) in this report. Sutherland and Harlow's 

paper, however, is not included in the synonymies. 

PRESENT STUDY 

Our biostratigraphic investigation of the Amsden 

Formation of Wyoming depends largely upon brachiopods and foraminifers; the need, therefore, for 

a comprehensive taxonomic study of the brachiopods 

is basic. The brachiopods seem to occur somewhat 

more widely than the foraminifers, which were not 

found, for example, in the Horseshoe· Shale Member 

of this formation in the Wind River Range, the 

area where brachiopods are perhaps the most abundant. 

My interest in the biostratigraphy of the Amsden 

Formation stems from various discussions with the 

late J. S. Williams, who was greatly concerned with 

the stratigraphic problems connected with this formation in western Wyoming; also with W. H. Easton 

who, during the time he shared an office with me 

in Washington, D.C., was engaged in writing his 

report on the formations and faunas of similar age 

in central Montana (Easton, 1962). Field studies 

during the early summer of 1955 with Easton, L. S. 

Gardner, P. E., Cloud, Jr., and R. J. Ross, Jr., afforded 

the opportunity to study some of the sections and 

collect fossils from them. 
D4 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

The present study has been largely one of previously collected material. An attempt has been made 

to examine all the fossils upon which previous taxonomic work and definitive age determinations were 

based. Material has been borrowed from several 

universities and from the U.S. National Museum. 

The Amsden brachiopod fauna considered in the 

present report includes about three times the number 

of taxa that have been described and illustrated by 

earlier authors. All previously published material 

has been restudied and reevaluated, including many 

specimens upon which earlier faunal lists were based. 

As every one of the previously described taxa is now 

known to have come from the Mississippian parts 

of the formation, the Pennsylvanian components of 

the fauna are here described and illustrated for the 

first time. Some of the species recorded from Wyoming for the first time are the same as those from 

equivalent rocks in central Montana. Where applicable, the brachiopods described by Easton (1962) 

from the Carboniferous formations in that region 

have also been restudied. 

The more than 4,900 brachiopods studied represent the labors of many collectors in Wyoming. They 

include W. G. Bell, C. A. Biggs, Eliot Blackwelder, 

C. C. Branson, E. B. Branson, N. H. Brown, C. A. 

Burk, P. E. Cloud, Jr., N. H. Darton, C. H. Dobbin, 

J. T. Dutro, Jr., Mackenzie Gordon, Jr., D. K. Greger, 

L. G. Henbest, I. A. Keyte, E. M. Kindle, W. T. Lee, 

J. D. Love, P. S. Morey, W. W. Rubey, W. J. Sando, 

and J. S. Williams. The 66 taxa discussed in this 

paper probably represent a very high percentage of 

the total brachiopod fauna of the Amsden Formation. 

ACKNOWLEDGMENTS 

I am indebted to A. G. Unklesbay, J. A. Wolleben, 

R. L. Ethington, R. E. Peck, and J. H. Stitt of the 

University of Missouri and to D. W. Boyd of the 

University of Wyoming for extended loans of types 

and considerable unfigured material from the Amsden Formation in the university collections; and to 

Copeland MacClintock of Yale University's Peabody 

Museum for a similar loan of Amsden fossils collected in the Washakie Range by J. D. Love. I also 

want to thank G. A. Cooper of the U.S. National 

Museum for permission to study the Amsden fossils 

housed in the museum collection. 

This paper has profited from the counsel and encouragement provided by my colleague G. W. Andrews with regard to the genus Composita. I am 

likewise indebted to R. E. Grant for suggestions and 

to J. L. Carter and J. T. Dutro, Jr., for review of this 

paper. 

FOSSIL LOCALITIES 

For the purpose of simplication, the collections 

studied during our investigations of the Amsden 

Formation and its faunas have been given numbers 

from 1 to 160. Material is included from U.S. Geological Survey (USGS) and U.S. National Museum 

(USNM) ·collections and collections in the University 

of Wyoming (UW), University of Missouri (UM), 

and Yale University's Peabody Museum (YPM). The 

permanent numbers of these collections, locality 

descriptions, and complete lists of identified fossils 

are given in the first report in this series on the 

Amsden Formation (Sando and others, 1975). A 

checklist of the brachiopod collections is given in 

table 3. 

COMPOSITION OF THE FAUNA 

The brachiopod fauna of the Amsden Formation, 

which includes beds ranging from middle Chesterian 

to Atokan in age, is made up of several different 

subfaunas or faunules. Their overall composition is 

shown in table 1, which lists the families and genera 

of Amsden brachiopods, the number of specimens 

belonging to each of them, and the percentage of 

the total brachiopod fauna studied that each represents. The Mississippian and Pennsylvania specimens have been separated in the table; the totals 

for each genus are given in the right-hand pair of 

columns. The Mississippian specimens outnumber 

the Pennsylvanian about five to one. Numerically, 

the compositas and anthracospirifers are the most 

abundant, making up slightly more than two-thirds 

of the fauna; some productoid and orthotetoid brachiopods are also present. All four of these groups 

have proven useful biostratigraphically in subdivding the Amsden into faunal zones. 

The brachiopod species are listed in table 2. This 

table gives their occurence in each of the 110 collections of Amsden brachiopods used in this study. A 

checklist of the collections is given in table 3. 

RELATION TO THE MISSISSIPPIAN-PENNSYLVANIAN 

BOUNDARY 

None of the species of the four groups mentioned 

above crosses the Mississippian-Pennsylvanian 

boundary. In fact, of the 66 brac!liopod species and 

subspecies described in the systematic part of this 

report, only 5 have been recorded both in Mississippian and Pennsylvanian rocks. These are Lingula cf. 

L. ca1·bonaria Shumard, Schizophoria depressa 

Easton, S. aff. S. texana Girty, Eolissochonetes 

pseudoliratus (Easton), and Pugnoides quinqueplecis Easton. The last two begin near the top of the 

Mississippian section, where their Mississippian age 

is indicated by associated species. Eol1~ssochonetes 
BRACHIOPODA OF THE AMSDEN FORMATION D5 

TABLE 1.-Taxonomic relationships and relative abundance of brcwhiopods in the Amsden Formation of Wyoming 

Mississippian specimens Pennsylvanian specimens Totals 

Percent of total Percent of total Percent of total 

Family Genus Number identifiable identifiable Number identifiable 

brachiopods brachiopods Number brachiopods 

Lingulidae. _________ [.;ingula ------------ Discinidae __________ Qrbiculoidea _______ _ 

Entletidae __________ Schizophoria -------- Rhipidomellidae _____ Rhipidomella ______ _ Me1ekellidae ________ Qrthotetina _______ _ 

Pulsia ------------- Schuchertellidae ____ Schuchertella ------- Orthotetidae ________ Orthotetes ---------

Derbyia ------------ Chon-etidae _________ Eolissochonetes ____ _ Mesolobus _________ _ 

Overtoniidae _______ Scolonconcha ------- Marginiferidae _____ lnflatia ------------ Rugoclostus _______ _ Produdidae ________ D·iaphragmus 

Carlinia ------------ Echinoconchidae ____ Echinoconchus _____ _ 

Buxtonii'dae ________ Flexaria ----------- Juresania _________ _ 

Dictyoclostidae _____ An.tiquatonia ------- Linoproductidae ____ Ovatia ------------- Linop't·oouctus Stenoscismatidae ___ C oleclium __________ _ 

5 

8 

8 

8 

3 

11 

50 

122 

103 

89 

103 

2 

4 

37 

0.10 

.16 

.16 

.16, 

.06 

.22 

1.01 

2.47 

2.09 

1.80 

2.09 

.04 

.08 

.75 

.20 

3 

2 

53 

30 

4 

41 

19 

127 

6, 

2 

18 

11 

7 

103 

103 

0.06 

.04 

1.07 

.61 

.08 

.83 

.39 

2.57 

.12 

.04 

.36 

.22 

.14 

2.09 

2.09 

8 

10 

61 

30 

8 

7 

11 

91 

19 

249 

6 

2 

103 

18 

89 

103 

0.16 

.20 

1.23 

.61 

.16· 

.14 

.22 

1.84 

.39 

5.04 

.12, 

.04 

2.09 

.36 

1.80 

2.09 

.22 

.04 

.14 

? __________ Pugnoides _________ _ 

Athyridida'e ________ Cleiothyridina _____ _ Composita _________ _ 

Elythidae __________ Torynifer ---------- Spiriferidae ________ Anthracospirifer ____ _ Brachythyrina _____ _ Neospirifer ________ _ 

Spiriferinidae ______ Reticulariina. ______ _ Retziidae __________ Eumetria ---------- Cranaenidae _______ Girtyella __________ _ 

10 

263 

26 

2,203 

3 

931 

6 

1 

93 

75 

3 

5.33 

.53 

44.64 

.06 

18.87 

.12 

.02 

1.88 

1.52 

.06 

6 

177 

55· 

.12 

3.59 

1.11 

11 

2 

7 

107 

37 

103 

10 

263 

32 

2,380 

3 

986 

6 

1 

93 

75 

3 

1 

2.17 

.75 

2.09 

.20 

5.33 

.65 

48.23 

.06 

19.98 

.12 

.02 

1.88 

1.52 

.06 

? __________ Selenella? .02 1 .02 

Total ---------------------------- 4,168 84.44 767 15.53 99.97 

pseudoliratus occurs at one locality in association 

with Foramanifera of Mamet's Zone 19. 

Of the other 61 taxa described in this report, 41 

are restricted to the Mississippian and 20 to the 

Pennsylvanian. 

GEOGRAPHIC AND STRATIGRAPHIC 

DISTRIBUTION OF THE BRACHIOPODS 

Because the Amsden Formation is transgressive 

and contains several different facies, it is difficult, 

if not impossible, to discuss at the sam.e time the 

distribution of the brachiopods in terms of the rocks 

(distribution in the formation and its members) and 

in terms of geologic time (distribution in time-rock 

units such as system and series). Evidence derived 

from both the brachiopods and foraminifers has 

shown, for example, that the Horseshoe Shale Member is middle to late Chesterian (Late Mississippian) 

age in western Wyoming and late Morrowan (Early 

Pennsylvanian) age in the Rawlins uplift in southcentral Wyoming. The overlying Ranchester Limestone Member is very late Chesterian and early 

Morrowan age in western Wyoming and late Morrowan and Atokan age in the Rawlins hills. 

To approach this part of the discussion with a 

sense of order, let us first consider the distribution 

of the brachiopod assemblages in each member by 

counties, generally moving in a direction from west 

to east (actually west to north to east to southeast), 

to obtain a roughly chronological sequence from 

older to younger beds. Following this we will review 

the brachiopod biostratigraphy of the Amsden Formation from a zonal and time-rock viewpoint. 

DARWIN SANDSTONE MEMBER 

No brachiopods or any other fossils of Amsden 

Age have been found in the Darwin Sandstone 

Member. Brachiopods and conodonts were collected 

from limestone lenses within the lower part of the 

sandstone section at Little Tongue River on the 

northeast flank of the Bighorn Mountains, Sheridan 

County, but these were determined as having the 

same age as the Bull Ridge Member of the Madison 

Limestone and therefore are not considered part of 

the Amsden fauna. This occurrence is discussed by 

Sando, Gordon, and Dutro (1975). 

MOFFAT TRAIL LIMESTONE MEMBER 

The Moffat Trail Limestone Member, proposed 

and described by Sando Gordon and Dutro (1975), 

is a lateral equivalent of the Horseshoe Shale Mem-
TABLE 2.-Brachiopod fauna of the Amsden Formation of Wyoming 

Horseshoe Shale Member 

2 3 4 5 7 8 19 21 22 26a 26b 27 28 29 30 31 32 34 35 36a36b36c36d36e 38 39 41 42 43 44 45 46 47 48 53 54 

Lingula cf. L. carbonaria Shumard ------------------------ Orbiculoidea w11cnningensis B1·anson and Greger ------------ sp. A ------------------- ______ --------- ______ --------

sp. B ------------------------------------------------ -- -- X Schizophoria depressa Easton ------------------------------

aff. S. texana Girty ----------------------------------- Rhipidomella carbonaria (McChesney) --------------------- Orthotetina amsdensis (Branson and Gregor) 

Pulsia delira n. sp ---------------------------------------- sp. A _____________ ------ ___ --------------- __________ _ 

Schuchertella poposiensis (C. Branson) -------------------- Orthotetes kaskaskiensis bransonorum n. subsp sp. A 

sp. --------------------------------------------------- Derbyia cf. D. robusta (Hall) ----------------------------- Orthotetoid, gen. and sp. indet ---------------------------- Eolissochonetes pseudoliratus (Easton) 

M esolobus sp __________ - ---------------------------------- Scoloconcha globosa (Mather) 

lnflatia lovei n sp ---------------------------------------- Rugoclostus williamsi n. sp -------------------------------- Diaphragrnus cestriensis (Worthen) 

nivosus n sp ----------------------------------------- Carlinia amsdeniana Gordon 

Carlinia amsdeniana Gordon ------------------------------- Echinoconchus sp. A 

Flexaria sp ___ --- _ ---------------------------------------- Juresania sp _______________________ ----------------------

A ntiquatonia cf. A. coloradoensis ( Girty) 

blackwelderi n. sp 

sp ---------------------------------------------------- Ovatia croneisi ( C. Branson ) 

muralis n. sp ----------------------------------------- Linoproductus eastoni n. sp ------------------------------- planiventralis Hoare _____________ --------- ___ ------- __ 

Linoproductid, gen. and sp. indet 

Productoid, gen. and sp indet ----------------------------- Pugnoides quinqueplecis Easton 

Colediurn fragum n. sp ----------------------------------- Cleiothyridina atrypoides saginata n. subsp 

hirsuta darwinensis n. subsp --------------------------

aff. C. elegans Girty ---------------------------------- aff. C. sublamellosa (Hall) sp. indet ______________________________ ---------------

Composita subquadrata (Hall) 

aff. C. laevis Weller -----------------------------------

sigma n. sp ------------------------------------------- poposiensis n. sp 

sulcata Weller 

ovata Mather ----------------------------------------- elongata Dunbar and Condra -------------------------- subtilita (Hall) 

sp. indet -------------------------------------------- _ Torynifer setiger (Hall)? --------------------------------- A nth racospirifer cur1>ilateralis curvilateralis (Easton) ____ _ 

curvilaterolis brutus n. subsp. 

shawi exoletus n. subsp 

shawi shawi n. subsp --------------------------------- welTeri welleri (B•·anson and Greger) 

u•ellPri lincolnensis n. subsp -------

X X X X 

X X 

)( 

X X 

X X X 

X X ,, 

v 

occiduus (Sadlick) ----------------------------------- X aff. A. occiduus ( SadHck), form A 

aff A. occid1t1ts ( Sadlick), form B rawlinsensis n. sp sp. indet __________ ------ ____________________ -------- _ 

Brachythyrina washakiensis n. sp --------------------------

Neospirifer praenuntius Easton ---------------------------- Rdiculariino. brou·ni (Branson and Greger) 

Reticulariina? sp. indet 

Eumetria sulcata Burk ------------------------------------ Eumetria? sp. indet --------------------------------------- Girtyella cf. G. indianensis (Girty) 

Selenella? waltcri C. Branson 

X X 

X 

X X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X X 

X 

)( 

X 

X X X 

)( )( 

X X 

X 

X X X 

X X 

X X 

X 

X 

X 

X 

X 

X -- X 

X 

X 

X X X 

X 

X 

X 

X X X X X 

X 

X 

X 

X X X X X ? X X 

X X -- -- -- -- -- X 

X -- X -- __ X X X -- X 

X X X X X X X X 

·x 

X X -- -- -- -- -- -- X X X X X X X 

X 

X X 

X X 

X 

X 

X 

X 

X 

X 

X X X 

X 

X -- X X X 

X X 

X X 

X -- -- X 

X 

X X X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X 

X X X 

X X 

X 

X 

X X 

X X 

X X 

X X 

X 

X X X 

X 

X X 

X X 

X 

X 

X 

X X 

X X 

? 

X 

t:l 

~ 

~ 

::t: 

t_%j 

> 

~ 

UJ. 

tj 

trJ 

z 

~ 

0 

~ 

~ 

> 

~ ~ 

0 

z 

-

~ ~ 

UJ. 

UJ. 

~ 

UJ. 

UJ. 

~ 

"'tt 

"'tt 

~ 

> z 

> z 

t::l 

"'tt 

t_%j 

z 

z 

UJ. 

1-<1 

t-t 

< 

> z 

~ 

> z 

-

0 

~ 

~ 

1-<1 

0 

~ ~ 

z 

C) 
TABLE 2.-Brachiopod fauna of the Amsden Formation of Wyoming-Continued 

Horseshoe Shale Member-Continued I Moffat Trail Limestone Member 

69 117118137138 149150151152153 154155156157158 159 A B C D E F 172 73 75 76 77 78 79 92 93 109120121122145 

Lingula cf. L. carbonaria Shumard --------------------------- Orbiculoidea wyomingensis Branson and Greger ----------------

sp. A _ --------------------------------------------------- sp B ------- ___ --------- _________ --------------- _________ _ 

Schizophoria depressa Easton 

aff. S. texana Girty --------------------------------------- Rhipidomella curgonaria {McChesney) ------------------------ Orthotetina amsdenensis (Branson and Greger) 

Pulsia delira n. sp -----------· -------------· 

sp. A ---------------------------------------------------- Schuchertella poposiensis (C. Branson) ----------------------- cf. Orthotetes kaskaskiensis bransonorum n. subsp 

sp. A ---------------------------------------------------- sp ------------------------------------------------------- Derbyia cf. D. robusta Hall ---------------------------------· Orthotetoid, gen. and sp indet -------------------------------- Eolissochonetes pseudoliratus (Easton) 

Eolissochonetes? suttoni {C. Branson) 

Mesolob~ts sp __________ -------------------------------------- Scoloncha globosa (Mather) 

lnflatia lovei n. sp ------------------------------------------- Rugoclostus williamsi n. sp ----------------------------------- Diaphragmus cestriensis (Worthen) 

nivosus n. sp -------------------------------------------- Carlinia amsdeniana Gordon Echinoconchus sp A 

Flexaria sp --------

Juresania sp ______ ------------------------------------------- A ntiquatonia cf. A. coloradoensis ( Girty) 

blackwelderi n. sp ----------------------------------------

sp ------------------------------------------------------- Ovatia croneisi (C. Branson) 

muralis n. sp -------------------------------------------- Linoproductus eastoni n. sp ----------------------------------- planiventralis Hoare _ ------------------------------------- Linoproductid, gen. and sp. indet ----------------------------- Productoid, gen and sp. indet --------------------------------- Pugnoides quinqueplecis Easton ------------------------------ X 

Coledium fragum n. sp -------------------------------------- Cleiothyridina atrypoides saginata n. subsp ------------------· 

hirsuta darwinensis n. subsp ------------------------------

aff. C. elegans Girty -------------------------------------- aff. C. sublamellosa (Hall) -------------------------------

sp. indet ------------------------------------------------- X 

Com1Josita subquadrata {Hall) 

aff. C. laevis Weller -------------------------------------- sigma n. sp ---------------------------------------------- poposiensis n. sp ----------------------------------------- sulcata Weller -------------------------------------------- ovata Mather ___________________ --------------------------

elongata Dunbar and Condra ----------------------------- subtilita (Hall) sp, indet ___________ -------- _________ ---------------------

Torynifer setiger (Hall)? ------------------------------------- A nthracospirifer curvilateralis curvilateralis (Easton) -------- curvilateralis brutus n. subsp 

shawi exoletus n. subsp 

shawi shawi n. subsp ------------------------------------- u•PlT<>ri •"AllPri (Branson and Greger) 

welleri lincolnensis n. subsp ------------------------------ occiduus ( Sadlick) --------------------------------------- aff. A. occiduus ( Sadlick), form A 

aff. ~- occjduus {Sadlick), form B ------------------------

rawltnsensts n. sp ---------------------------------------- sp. indet ------------------------------------------------- Brachythyrina washakiensis n. sp ----------------------------- Neospirifer praenuntius Easton ------------------------------- Reticulariina browni (Branson and Greger) ------------------- X 

Reticulariina? sp indet --------------------------------------- -· Eumetria sulcata Burk ---------------------------------------- X Eumetria? sp. indet ----------------------------------------- Girtyella cf. G. indianensis (Girty) 

Selenella? walteri C. Branson 

X 

X X 

X 

X X 

X 

X X 

X X 

X 

X 

X X 

X X 

X 

X X X 

X X 

X X X 

X X 

X 

X X 

X X X 

X 

X X 

X X X 

X 

X 

X X 

-- -- -- -- X -- X 

X 

X 

X 

X 

X 

X X 

X 

X 

X 

X 

X X 

X 

X 

X X 

X ? X X X 

X 

X 

X 

X 

X 

X 

X 

X X 

X 

X 

X 

X X X 

X X 

X 

X 

X 

X 

to 

~ 0 

ti: 

~ 

0 

1-0 

0 

t:1 

> 

0 

~ 

1-3 

~ 

t_:l:j 

> 

~ w 

t1 

t_:l:j 

z 

"%j 

0 

~ 

~ 

> 1-3 

~ 

0 

z 

t:1 

-::t 
TABLE 2.-Brachiopod fauna of the Amsden F·ormation of Wyoming-Continued 

Ranchester Limestone Member 

6 13 14 15 52 63 67 68 82 83 84 85 86 87 89 94 95 96 97 98 99 100101129130 131133134136139 uo 141142143146148160 

Lingula cf. L. carbonaria Shumard ------------------------ Orbiculoidea wyomingensis Branson and Greger ------------

sp. A _ --------- _ -------------------------------------- sp. B ------------------- _ -- _ -- _ ----------------------- Schizoplwria f[epressa Easton ------------------------------ __ __ __ __ X 

aff. S. texana Girty ----------------------------------- -- X -- -- -- -- X X Rhipidomella carbonaria (McChesney) --------------------- __ -- -- -- __________ -- -- X X Orthotetina amsdenensis (Branson and Greger) ------------ _________ _ 

Pulsia delira n. sp ---------------------------------------- -- -- -- -- X sp. A ________________________________________________ _ 

Schuchcrtella poposiensis (C. Branson) -------------------- Orthotetes kaskaskiensis bransonorum n. subsp ------------- sp. A 

sp ---------------------------------------------------- Derbyia cf. D. robusta (Hall) ----------------------------- X 

Orthotetoid, gen. and sp. indet ---------------------------- __ -- __ -- __ __ __ __ __ X 

Eolissochonetes pseudoliratus (Easton) -------------------- __ -- __ -- ____ X 

Eolissochonetes? suttoni (C. Branson) --------------------- -- -- -- --

Mesolobus sp --------------------------------------------- X -- -- X 

Scoloconcha globosa (Mather) ----------------------------- -- X 

lnfiatia lovei n. sp ---------------------------------------- Rugoclostus williamsi n. sp ______________________________ _ 

Diaph ragmus cestriensis (Worthen) 

nivosus n. sp ----------------------------------------- Carlinia amsdeniana Gordon -------------------------------

fi:chinoconchttB sp. A -------------------------------------- X X 

'F'lexaria sp ----------------------------------------------- -- -- Juresania sp ---------------------------------------------- __ -- X 

Antiquatonia cf. A. coloradoensis (Girty) ------------------ X X X -- -- X X 

blackwelderi n. sp ------------------------------------ -- -- -- -- -- -- -- -- X X SR ----------------------------------------·------------ Ovatia croneisi (C. Branson) 

muralis n. sp ----------------------------------------- Linoproductus eastoni n. sp -------------------------------

planiventralis Howre ---------------------------------- X 

Linoproductid, gen. and sp. indet 

~~~~~f~~~d,q~f~q:e~t~fs· ~!~~~-=========================== -- -- -- -- -- -- -- -- X 

Coledium fragum n. sp ------------------------------------ Cleithyridina atrypoides saginata n. subsp 

hirsuta darwinensis n. subsp ---------------------------

aff. C. elegans Girty ---------------------------------- aff. C. sublamellosa (Hall) 

sp. indet _ --- ______ - ----------------------------------- Comvosita subquadrata (Hall) 

aff. C. laevis We!Jer ----------------------------------- sigma n. sp ------------------------------------------ __ -- -- -- __ -- -- -- X 

poposiensis n. sp_ sulcata Weller _. 

ovata Mather ----------------------------------------- -- X X -- -- -- -- X elongata Dunbar ·and Condra -------------------------- -- -- --

subtilita (Hall) --------------------------------------- X -- -- X sp. indet _________________________ --------------------

Torynifer setiger (Hall)? --------------------------------- Anthracospirifer curvilateralis curvilateralis (Easton) -----

curvilateralis brutus n. subsp -------------------------

shawi exoletus n. subsp ------------------------------- -- -- -- -- __ -- -- -- X 

shawi shawi n. subsp --------------------------------- __ -- __ __ __ __ __ __ X 

welleri welleri (Branson and Greger) ----------------- -- -- -- -- -- -- -- -- -- wclleri lincolnensis n. subsp --------------------------- -- -- -- -- __ -- -- -- X 

occiduus (Sadlick) ---------------------------.. ------- X -- X ? -- -- -- -- -- X X aff. A. occidttus (Sadlick), form A -------------------- aff. :t-· oc~iduus ( Sadlick), form B rawl1nsensts n. sp ________ ----- ___ ---------------------

sp. indet --------------------------------------------- __ X -- __ X 

Brachythyrina washnkiensis n. sp 

Neospirifer praenuntius Easton ---------------------------- Reticulnriina browni (Branson and Greger) 

Reticulariinn? sp. indet 

Eumetria sulcata Burk ------------------------------------ Eumetria? sp. indet ------------------------------------- Girtyella cf. G. indianensis (Girty) 

Selenella? walteri C. Branson 

X 

X 

X 

X X X 

X 

X 

X X 

X 

X 

X 

X X 

X 

X 

X 

X 

X 

-- -- -- -- -- -- X X X X X X 

X 

X 

X 

X X X 

X 

X X 

X 

X X 

X 

X 

X 

X X 

X X 

X -- X 

X 

X -- X 

X 

X 

X 

X X 

X 

X 

t:1 

00 

~ 

~ 

tr:l 

> 

~ 

lfl 

t1 

tr:l 

z 

~ 

0 

~ 

~ 

> 

~ 

1-1 

0 

z 

~ 1-1 

r,p. 

lfl 

1-1 

lfl 

lfl 

1-1 

~ 

~ 1-1 

> z 

> z 

t1 

~ 

tr:l 

z 

z 

lfl 

1-<l 

~ 

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> z 

1-1 

> z 

-

0 

~ 

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1-<l 

0 

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z 

Q 
Collection 

No. in report 

Permanent 

institutional 

locality No. 

1 ------ USGS 5441-PC 

2 ------ USGS 8071-PC 

3 ------ USGS 3139-PG 

4 ------ USGS 3140-PC 

5 USGS 3885-PC 

6 USGS 3843-PC 

7 ------ USGS 21727-PC 

8 ------ USGS 21728-PC 

9 ------ Shaw collection 

13 ----- USGS 21729-PC 

14 USGS 21725-PC 

15 USGS 5864-PC 

19 UW 2997 I 6A 

21 ----- UW 3099/9B 

22 _____ UW 3099/9A 

26a ____ USGS 19284-PC 

26b ____ USNM 487 

27 USGS 19·283-PC 

28 UW 3199/19B2 

29 UW 3199/19B3 

30 UW 3199/19B4 

31 UW 3~199/19B5 

3·2 UW 3199/19B6 

34 UW 3199/19B8 

35 UW 3199/19A 

36a UM numbers 

36b ____ UM numhe.rs 

36c ____ UM numbers 

36d UM numbers 

36e ____ USNM 487A 

38 USGS 16397-PC 

39 USGS 14025-PC 

41 USGS 19·156-PC 

42 UW 43106/19A 

43 UW 43106/19B 

44 YPM 5154A-T, 

20103, 20106 

45 USGS 2'1719-PC 

46 ----- USGS 1619·7-PC 

47 ----- USGS 16198-PC 

48 YPM 20101-20110 

52 USGS 2461-PC, 

2461A-PC 

53 USGS 19241-PC 

54 USGS 19240-PC 

BRACHIOPODA OF THE AMSDEN FORMATION D9 

TABLE 3.-Checklis·t of brachiopod collections 

Name of locality Mountain range County Location Member 

Cherokee Spring_ Rawlins hills _ Carbon ______ Probably in SW% sec. 11, Horseshoe. 

T. 21 N., R. 88 W. ____ do --------- ____ do ___________ do ___________ do -------------------- ____ do --------- ____ do ___________ do------- NW% SW14 sec. 11, T. 21 N., 

R. 88 W. 

Cherokee Peak ______ do ___________ do _______ NW% s.ec. 10, T. 21 N., R. 88 

w. ____ do --------- ____ do ___________ do _______ SE%NW% sec. 10, T. 21 N., 

R. 88 w. 

Do. 

Do. 

Do. 

Do. 

Rawlins US 287 _____ do ___________ do _______ Probably NW%.NW 14 sec. 32, Ranchester. 

T. 22 N., R. 87 W. 

Meadow Ranch ______ do ___________ do _______ SW1,4NE14 sec. 25, T. 22 N., Horseshoe. 

R. 88 w. ____ do --------- ____ do ___________ do _______ SW1;4NE14 sec. 25, T. 22 N., Do. 

R. 88 w. ____ do- --------- ____ do ___________ do _______ NE% sec. 25, T. 22 N., R. Do. 

88 w. ____ do --------- ____ do ___________ do _______ SW14NE1;4 sec. 25, T. 22 N., Ranchester. 

R. 88 w. 

Buck Spring ________ do ___________ do _______ NW% sec. 33, T. 2.3 N., R. 88 Do. 

w. 

Belle Springs _______ do ___________ do _______ SE14NE14 sec. 29, T. 23 N., Do. 

R. 88 W. 

Beaver Creek ___ Wind River Fremont _____ NW14 sec. 6, T. 29 N., R. 97 Horseshoe. 

Range. W. 

South Pass _________ do ___________ do _______ Center sec. 9, T. 30 N., R. 99 

w. ____ do --------- ____ do ___________ do _______ ---~do -------------------- Amsden Hill ________ do ___________ do _______ Probably SW14 sec. 32, T 31, 

N., R. 99 W. ____ do --------- ____ do ___________ do ___________ do -------------------- Cherry Creek _______ do ___________ do _______ Probably s1ec. 30, T. 31 N., R. 

9•9 w. ____ do --------- ____ do ___________ do _______ SE 14NW14 s~ec. 19, T. 31 N., 

____ do ____ do ____ do ____ do ____ do 

____ do 

--------- ____ do ------- --------- ____ do ______ _ --------- ____ do ______ _ --------- ____ do ______ _ --------- ____ do ______ _ 

--------- ____ do -------

R. 99 W. ____ do ___________ do -------------------- ____ do ___________ do --------------------

____ do ___________ do -------------------- ____ do ___________ do --------------------

____ do ___________ do -------------------- ____ do _______ NW14 sec. 19, T. 31 N., R. 99 

w. ____ do --------- ____ do ___________ do _______ Sec. 19, T. 31 N., R. 99 W __ _ Cherry Creek? ______ do ___________ do _______ Same but labeled sec. 31, T. 

19 N., R. 99 W. 

Near Lander __ _ 

Little Popo Agie 

River. 

____ do ___________ do _______ Exact locality not known __ _ 

____ do ___________ do ___________ do --------------------

Cherry Creek __ _ 

Little Povo Agie 

Canyon. ____ do ---------

____ do ___________ do ------- ____ do------- ____ do ______ _ 

____ do ___________ do ______ _ 

Soda Creek _ _ _ _ _ Washakie 

Range. 

Teton ______ _ 

Sec. 19, T. 31 N., R. 99 W __ _ 

NW14NW%, sec. 19, T. 31 N., 

R. 99 w. 

SE 1;.iSE 14 sec. 13, T. 31 N., 

R. 100 w. 

Sec. 5, T. 45 N., R. 110 W __ _ 

Horse Greek ________ do _______ Fremont _____ SW% sec. 19, T. 43 N., R. 

106 w. ____ do --------- ____ do ___________ do ___________ do -------------------- ____ do --------- ____ do ___________ do _______ Sec. 19, T. 43 N., R. 106 N __ 

Livingston ____ do ___________ do _______ SW14SW14 sec. 29, T. 43 N., 

Ranch. R. 106 W. 

Wiggins Fork ______ do ___________ do _______ SW14 sec. 7, T. 42 N., R. 10·5 

w. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

Do. 

____ do --------- ____ do ---------

____ do ___________ do ___________ do -------------------- Do. 

North Fork, 

Crazy Woman 

Greek. 

South Fork, 

Rock Creek. 

____ do ---------

____ do ___________ do ___________ do -------------------- Do. 

Bighorn Johnson _____ SE14 sec. 28, orNE% sec. 33, Ranchester. 

Mountains. T. 49 N., R. 83 W. 

____ do ___________ do _______ SW% sec. 25, T. 52 N., R. 84 Horseshoe. 

w. ____ do ___________ do ___________ do -------------------- Do. 
DlO THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

CoHeetion Permanent No. in institutional 

report locality No. 

63 USGS 22206-PC 

67 USGS 16215-PIC 

68 USGS 22204-BC 

69 USGS 16216-PC 

72 USGS 6957-PC 

73 ----- USGS 6960-PC 

75 ----- USGS 22986-PC 

76 ----- USGS 22987-PG 

77 ----- USGS 69·60A-PC 

78 ----- USGS 6960B-PG 

79 USGS 22981-PC 

82 USGS 22983-PC 

83 ----- USGS 22988-PC 

84 ----- USGS 22989-PG 

85 ----- USGS 2'2990-PC 

86 ----- USGS 6960-PC 

87 ----- USGS 22991-PC 

89 ----- USGS 2.2993-PC 

92 USGS 69·65-PC 

93 USGS 6951-PC 

94 USGS 6965A-PC 

95 USGS 6951A-PC 

916 USGS 17908-PC 

97 USGS 7965B-PC 

98 ----- USGS 6951B-PC 

99 ----- USGS 6965-C-PC 

100 ---- USGS 6965D-PC 

101 ____ USGS 6965E-PC 

109 ---- USGS 23002-PC 

117 ---- USGS 18788-PC 

118 ____ USGS 16207-PC 

120 USGS 18791-PC 

121 USGS 16208-PC 

122 ---- USGS 16·209-PC 

129 ---- USGS 23000-PC 

130 ---- USGS 18786-PC 

131 ---- USGS 16·210-PG 

133 ---- USGS 6189-PC 

134 ---- USGS 6192-PC 

136 ____ USGS 6~190-PC 

137 ____ USGS 6191-PC 

138 ---- USGS 6191B-PC 

139 ____ USGS 6191A-PG 

140 ---- USGS 6191C-PC 

141 USGS 6193-PC 

142 ---- USGS 6193A-PC 

143 ____ USGS 6194-PC 

145 ---- USGS 23006-BC 

146 ____ USGS 23004-PIC 

148 ____ USGS 18776-PC 

149 USGS 20229-PC 

150 USGS 24055-PC 

151 ____ U8GS 24051-PC 

152 ____ USGS 24058-PC 

153 ____ USGS 24059-PIC 

TABLE 3.-Checklist of brac.hiopod collections----Continued 

N arne of locality Mountain range County Location Member 

Amsden Creek __ Bighorn Sheridan ____ S,W14 sec. 34, T. 57 N., R. 87 Ranchester. 

M.ountain.s. W. ____ do --------- ____ do ------- ____ do------- SW14 sec. 34,. T. 5·7 N., R. 87 Do. 

w. ____ do --------- ____ do------- ____ .do------- 8'E 14 sec. 32, T. 57 N., R. 87 Do. 

w. 

Devils Canyon ______ do _______ Garbon W% sec. 35, T. 9 S., R. 28 E_ Horseshoe. 

(Montana). . Bear Greek _____ Salt River Lincoln ------NE.l4rSW%SW% sec. 27, T. 33 Moffat TraiL 

Range. N., R. 117 W. 

Moffat Trail ________ do------- ____ do------- NW%NE14 sec. 3, T. 33 N., Do. 

R. 117 W. ____ do --------- ____ do ------- ____ do ------- ____ do -------------------- Do. ____ do --------- ____ do ------- ____ do ___________ do -------------------- D'O. 

____ do --------- ____ do ------- ____ do------- ____ do -------------------- Do. ____ do --------- ----do ------- ____ do ___________ do -------------------- Do. ____ do --------- ____ do ------- ____ do ___________ do -------------------- Do. ____ do _____________ do ------- ____ do ___________ do -------------------- Ranchester. 

____ do --------- ____ do ------- ____ do------- ____ do -------------------- Do. ____ do -·-------- ____ do ------- ____ do ___________ do -------------------- Do. 

____ do --------- _____ do ------- ____ do------- ____ do -------------------- Do. ____ do _____________ do ------- ____ do ___________ do -------------------- Do. 

____ do ---·------- ____ do ------- ____ do ___________ do -------------------- Do. 

Peak 9837 __________ do ------ ____ do ______ NE 14 sec. 34, T. 34 N., R. 117 Do. 

w. 

Cov;ey Cutoff ________ do ___________ do _______ NW14NE14 sec. 27, T. 34 N., Moffat Trail. 

R. 117 w. ____ do --------- ____ do ___________ do------- ____ do -------------------- Do. ____ do ---·------ ____ do ___________ do------- ____ do -------------------- Ranchester. ____ do --------- ____ do ___________ .do ___________ do -------------------- Do. ____ do --------- ____ do ___________ .do ___________ do -------------------- Do. ____ do --------- ____ do ___________ do ___________ do -------------------- Do. ____ do --------- ____ do ___________ do ____________ do -------------------- Do. ____ do --------- ____ do ___________ do ___________ do -------------------- Do. ____ do --------- ____ do ___________ do ___________ do --------------·------ Do. 

____ do --------- ____ do ------- ----.do ___________ do -------------------- Do. 

South Indian Snake River ____ ,do _______ NE% sec. 14, T. 38 N., R. 118 Moffat Tra.il. 

Creek. Range. W. 

Hoiback Canyon _ Hoback range_ T·eton _______ Sec. 2, T. 38 N., R. 115 W --- Horseshoe. ____ do --------- ____ do ___________ do ___________ do -------------------- Do. 

____ do --------- ____ do ------- ____ do ------- ____ do -------------------- Moffat Trail. ____ do --------- ____ .do ___________ .do ___________ do -------------------- Do. 

____ do --------- ____ do ------- ____ ,do ___________ do -------------------- Do. 

_. ___ do --------- ____ do ------- ____ do------- ____ do -------------------- Ranchester. ____ do --------- ____ do ___________ do ___________ do -------------------- Do. ____ do --------- ----·do ___________ do ___________ do -------------------- Do. 

Tosi Ridge _____ Gros Ventre Sublette _____ Sec. 1, T. 38 N., R. 112 W --- Do. 

R~ange 

Hodges Peak _______ do ___________ do _______ NW% s.e·c. 26, T. 39 N., R. Do. 

112 w. 

Granite Creek ______ do _______ Teton _______ Sec. 4, T. 39 N., R. 113 W ___ Do. 

Darwin Peak _______ do ___________ do ------- S% sec. 28, T. 40 N., R. 112 Hors.eshoe. 

w. ____ do --------- ____ do ___________ do ___________ do -------------------- Do. ____ do --------- ____ do ___________ do ___________ do -------------------- Ranchester. ____ do --------- ____ do ___________ ,do ___________ do -------------------- Do. 

Black Peak _________ do ___________ do _______ Probably s·ec. 7, T. 40 N., R. Do. 

112 w. ____ do --------- ____ do _______ . ____ do _______ Probably sec. 7 or 18, T. 40 Do. 

N., R. 112 W. 

Pyramid Peak ______ do ___________ ,do _______ Probably SE% sec. 6, T. 40 Do. 

N., R.113 W. 

Phillips Canyon _ Teton Range _____ do _______ SW14 sec. 16, T. 41 N., R. Moffat Trail. 

117 w. 

Glory Mountain _____ do ___________ do _______ SE% sec. 13, T. 41 N., R. 118 Ranchester. 

w. 

Darby Canyon ______ do ___________ do _______ NE14SE14 sec. 15, T. 43 N., Do. 

R. 118 W. 

Berry Creek ________ do ___________ do _______ NW% sec. 22, T. 47 N., R. Horseshoe. 

116 w. ____ do --------- ____ do-------. ____ do ___________ do -------------------- Do. ____ do _____________ do ___________ do ___________ do -------------------- D10. ____ do _____________ do ___________ do ___________ do -------------------- Do. ____ do _____________ do ___________ do ___________ do -------------------- Do. 
BRACHIOPODA OF THE AMSDEN FORMATION D11 

TABLE 3.-Checklist of brachiopod collections-Cootinued 

Collection 

No. in 

report 

Permanent 

institutional 

localtiy No. Name of locality Mountain range County Location Member 

154 ____ USGS 24060-PC Berry Creek ___ Teton Range _ Teton ------- NW1

4 sec. 22, T., 47 N., R. Horseshoe. 

116 w. 

155 ____ USGS 24052-PC ____ do --------- ____ do ------- ____ do ___________ do -------------------- Do. 

156 ____ USGS 2405·6-PG ____ do --------- ____ do ------- ____ do ___________ do -------------------- Do. 

157 ____ USGS 20230-PC 

158 ____ USGS 24053-PC 

159 ____ USGS 24050-PC 

160 ---- USGS 24057-PC 

A------ USNM Nos. 

~!~~~~~~~~~~~~ Enterprise ditch_ ~~=~ii Wind River ~~~~~~~ ~~~~~ Fremont ~~~~~~~ ____ _ ~~j~ ~=~~~~~~~~~~~~~~~~~~ Ranc~~Wr. Ran~. Horseshoe. B ______ _ ___ do ______ _ Amsden Hill ________ do ___________ do ______ _ Do. 

Do. 

Do. 

Do. 

Do. 

C __________ do------- Cherry Creek _______ do ___________ do------- D ______ _ ___ do ______ _ Youngs Basin ______ do ___________ do------- E __________ do ______ _ Near Lander _______ do ___________ do-------

F ______ _ ___ do ------- Fremont County _____ do ___________ do ______ _ 

ber, but it includes some beds in Lincoln County 

that probably are older than the lowest known in the 

Horseshoe. Characteristic of the Moffat Trail is its 

coral fauna which belongs to what is widely known 

as the Caninia Zone (K Zone of Dutro and Sando, 

1963, p. 1974). Brachiopods are not very common 

in the coral beds, but Composita, particularly C. 

subquadrata (Hall), and Anth'racospirifer curvilateralis brutus n. subsp. are present at several localities. Our 14 Moffat Trail brachiopod collections 

are from two counties in western Wyoming. 

Lincoln County.-Collections ( collns. 72, 73, 75-

79, 92, 93, 109) made in the Bear Creek, Moffat 

Trail, Covey Cutoff, and South Indian Creek sections have yielded the following brachiopods. The 

meaning of symbols: R, rare; X, fairly common; 

C, common; A, abundant. 

Pulsia sp. A --------------------------------------- R 

Orthotetes? sp -------------------------------------- R 

Dia.pkragmus cestriensis (Worthen) ------------------ C 

A utiquatonia sp _______ _ __ _ ________ _ __ _____ __ __ _____ R 

Ovatia muralis n. sp -------------------------------- X 

Linoproductid gen. and sp. indet --------------------- R 

Colediwm fragum n. sp ------------------------------ X 

Cleiothy'ridina aff. C. sublanwllosa (Hall) ------------- R 

Composita subquad,rata (Hall) ----------------------- C 

Composita sp. indet --------------------------------- C 

A nthracospirije1· cnrvilateralis curvilate1·alis (Easton) _ C 

Anthracospirifer curvilateralis brutus n. subsp ________ X 

Teton County.-Collections in the Hoback Canyon and Phillips Canyon sections ( collns. 120-122, 

145) include some of the same braciopods: 

Orthotetes kaskaskiensis bransonorum n. subsp ________ X 

Diaphragmus cestriensis (Worthen) ------------------ C 

O·vatia muralis n. sp -------------------------------- R 

Composita subquadrata (Hall) ----------------------- X 

Composta sp. indet ---------------------------------- X 

Anthracospirifer curv·ilateralis curvilateralis (Easton) _ C 

Neospirifer p1·aenuntius Easton ---------------------- R 

Eumetria? sp. indet --------------------------------- R 

HORSESHOE SHALE MEl\IBER 

Fifty collections of brachiopods from the Horseshoe Shale Member in four Wyoming counties and 

one adjacent county in Montana were studied. Of 

these more than four-fifths are Late Mississippian 

(Chesterian) in age, including the 17 from Teton 

County and 23 from Fremont County Wyo., and one 

from Carbon County, Mont. Farther to the east and 

southeast, however, the two collections from Johnson 

County and seven from Carbon County, Wyo. are 

Early Pennsylvanian (Morrowan) in age. 

Teton County.-Four separate faunules can be 

recognized in the Horseshoe Shale Member in Teton 

County, all of them Mississippian in age. The· first 

and probably the oldest occurs beneath the Moffat 

Trail Limestone Member in the section at Hoback 

Canyon (collns. 117, 118). 

Cmnposita aff. C. laevis Weller ----------------------- C 

Composita sp. indet --------------------------------- C 

An.thracospirifer curvilatcralis brutus n. subs.p -------- C 

This assemblage, despite its occurrence in beds of 

Horseshoe Shale Member lithology, is the same as 

that normally found in the Moffat Trail Limestone 

Member. 

The second assemblage is from Soda Creek in the 

Washakie Range (colin. 41) and contains the following brachiopods: 

Schizophoria depressa Easton ------------------------ R 

Orthotetoid, gen. and sp. indet ----------------------- R 

lnfla,tia lovei n. sp ---------------------------------- X 

Diaphragrnus nivosus n. sp -------------------------- X 

Antiquatonia? s,p ----------------------------------- R 

Cleiothyridina atrypoides saginata n. subsp ---------- R 

Composita aff. C. laevis Weller ----------------------- R 

Compo·sita subquadrata (Hall) ----------------------- C 

B1·achythyrina washak1~ensis n. s.p -------------------- X 

Reticulariina? s.p. inde<t ------------------------------ R 

Like the other assemblage, this faunule occurs in 

beds regarded as equivalent temporally to part of 
D12 THE AMSD-EN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

the Moffat Trail and its Caninia Zone fauna. The 

Soda Creek locality is unique in having Diaphragmus nivosus n. sp., Cleiothy1·idina atrypoides saginata n. subsp., and Brachythyrina washakiensis n. 

sp., which have not been found anywhere else in the 

Amsden formation. D. nivosus is a typical species 

in the Heath Shale of Montana where it is associated 

with Composita S'ltbquadrata (Hall), a species restricted to the Caninia Zone and its equivalents in 

the Amsden Formation. 

The third faunule occurs in the Darwin Peak section and is the one for which Girty (in Blackwelder, 

1918, p. 422) suggested a Mississippian age. The 

brachiopods at this locality (collns. 137, 138) are as 

follows: 

Cleiothyridina hirsuta darw,inensis n. subsp ___________ X 

Composita sigma n. sp ------------------------------ X 

Torynifer setiger (Hall)? --------------------------- R 

Anthrac,ospirifer shawi shawi n. subsp ---------------- X 

This represents the lower fauna of the same member in the Wind River Range, Fremont County. 

The fourth and highest faunule occurs in reddishgray shale and interlayered gray limestone of the 

Horseshoe Shale Member at Berry Creek and Elk 

Ridge in the Teton Range (collns. 149-159), which 

have yielded the fo~ • .ving brachiopods: 

Orthotetes kaskaskiensis bransonorum n. subsp ________ C 

Eolissochonetes pseudoliratus (Easton) --------------- A 

Ovatia croneisi (C. Branson)? ----------------------- R 

Composita sigma n. sp ------------------------------ X 

Anthraco•spirifer shawi exoletus n. subsp -------------- R 

Anthracospirifer welleri lincolnensis n. subs.p __________ A 

Anthracospirifer aff. A. occiduus (8adlick), form A____ A 

The anthracospirifers are facies controlled at this 

locality: A. shawi exoletus and A. weller·i lincolnensis are restricted to the limestone layers, and A. 

aff. A. occiduus, form A is found only in the shale. 

Associated foraminifers indicate latest Mississippian age for this assemblage. 

Fremont County.-Most of the earlier work on 

the fossils of the Amsden Formation has been based 

on localities in the Wind River Range, and all of 

them seem to have come from the Horseshoe Shale 

Member. In this area two assemblages have been 

recognized (Shaw and Bell, 1955; Shaw, 1955), 

a lower assemblage (Spirifer welleri fauna of Shaw, 

1955) and an upper assemblage (Spirifer "opimus" 

fauna of Shaw, 1955). By some fortunate circumstance the fossils of the upper zone are silicified, and 

many of them have been replaced by chert, whereas 

those of the lower fauna are calcareous. This condition is demonstrated by Bell's specimens (in the 

collections of the University of Wyoming) which 

he obtained in place by trenching the section at 

Cherry Creek. The faunal differences noted in comparing loose silicified fossils with calcareous ones 

are largely borne out by the roster of fossils collected in situ at the lower and higher levels. 

The lower fauna ( Carlinia amsdeniana assemblage) , ( collns. 21, 22, 26b-31, 36a [part], 36b 

[part], 43 [part], 44-48) at South Pass, Cherry 

Creek, Amsden Hill, Hors·e Creek, Wiggins Fork, 

and Livingston Ranch is as follows: 

Ling1da cf. L. carbona'ria Shumard ------------------- R 

Orbiculoidea wyomingensis Branson and Greger ------- R 

Orbiculoidea sp. A ---------------------------------- R 

Schizophoria depressa Easwn ------------------------ R 

Schizophoria aff. S. texana Girty --------------------- R 

Orthotetes kaskaskiensis bransonorum n. subsp -------- R 

Orthotetina amsdenensis (Branson and Grege·r) ------- R 

Ovatia c'i·oneisi (C. Branson) ------------------------ X 

lnflatia lovei n. s1p ---------------------------------- C 

Carlinia amsdeniana Gordon ------------------------- C 

Flexaria sp ---------------------------------------- R 

Ovatia croneisi (C. Branson) ------------------------- X 

Ovatia muralis n. sp -------------------------------- R 

Cleiothyridina hirsuta darwinensis n. subsp ----------- X 

Cleiothryidina aff. C. elegans Girty ------------------- R 

Composita sigma n. sp ------------------------------ C 

Composita poposiensis n. sp. (early form) ------------- R 

Torynifer setiger (Hall)? --------------------------- R 

Anthraco•spirifer welleri welleri (Branson and Greger) - C 

Anthracospirifer shawi shawi n. subsp ---------------- X 

Reticulariina browni (Branson and Greger) ----------- X 

Eumetria sulcata Burk ------------------------------ X 

Gitryella cf. G. indianensis (Girty) ----------------- R 

These include the fossils collected in place by Bell 

(in Shaw and Bell, 1955, fig. 1) 45 to 48 feet 

above the base of the Amsden at Cherry Creek, and 

fossils collected by Love (1939, p. 28) at Wiggins 

Fork. 

The higher fauna ( Composita popsiensis as:semblage), (collns. 19, 26a, 32, 34, 36a [part], 38, 42, 

43 [part]) is as follows: 

Orbiculoidea wyomingensis (Branson and Greger) ----- R 

Orthotetoid, gen. and sp. indet ----------------------- R 

Ovatia croneisi (C. Brans.on)? ----------------------- R 

Ovatia muralis n. sp? ------------------------------- R 

Producto,id, gen. and sp. indet ------------------------ R 

Pugnoides qu,inqueplecis Easton ---------------------- X 

Composita poposiensis n. sp -------------------------- A 

Cmnposita sulcata Weller ---------------------------- X 

Composita sp. indet --------------------------------- X 

Anthraco8tpirifer shawi exoletus n. subsp -------------- C 

Anthracospirifer aff. A. occiduus (Sadlick), form A --- R 

Eumetria sulcata Burk ------------------------------ X 

Included in this list are the fossils collected by Bell 

(Shaw and Bell, 1955, fig. 1) in place 65 to 68 feet 

above the base of the Amsden at Cherry Creek. 

These highest fossiliferous beds of the Horseshoe 

Shale Member in Fremont County are regarded as 

approximating in age the beds on Berry Creek, 
BRACHIOPODA OF THE AMSDEN FORMATION D13 

Teton County, that bear the same and similar 

anthracospirifers. The compositas, however, are different at the two localities, as C. poposiensis n. sp. 

is restricted to Fremont County. 

Carbon County, Mont.-On top of the bluffs of 

the Bighorn River opposite the mouth of Devil's 

Canyon, roughly one-quarter of a mile north of the 

Wyoming-Montana State line, a small collection of 

silicified brachiopods from a limestone layer about 

15 feet above the top of the 1\-Iadison Limestone 

( colln. 69) yielded the following brachiopods: 

Schuc.hertella cf. S. poposiensis (G. Branson) __________ R 

Pugnoides quinqueplecis Easton ---------------------- C 

Cleiothyridina sp. indet ----------------------------- R 

Reticulariina browni (Branson and Greger) ----------- X 

Eumetria sulcata Burk ------------------------------ R 

The presence of Pugnoides quinqueplecis and Eumetria sulcata in association in this faunule indicates an equivalence to the Composita poposiensis 

fauna in the Wind River Range. 

Johnson County.-In the Lake de Smet area, on 

the South Fork of Rock Creek, two collections 

( collns. 53, 54) from the Horseshoe Shale Member 

have provided fossils of Early Pennsylvanian age. 

The brachiopods are as follows : 

Orthotetes sp. A _______ ----------------------- ___ ___ X 

Juresania s.p --------------------------------------- R 

Antiquatonia cf. A. coloradoensis --------------------- R 

Linoproductus eastoni n. s1p -------------------------- C 

These fossils came from the basal 2 feet of the 

member and thus indicate Pennsylvanian age for 

the entire Horseshoe Shale Member in that area. 

Carbon County.-The Amsden Formation in the 

region of the Rawlins hills contains the youngest 

faunas found in this study. The Horseshoe Shale 

Member in that area contains brachiopods and mollusks of Morrowan age associated with the coral 

N eokoninckophyllum hamatilis Sando and N. inconstans Sando. Brachiopods from seven collections in 

the Cherokee Spring, Cherokee Peak, and Meadow 

Ranch sections ( collns. 1-5, 7, 8) are as follows : 

Orbiculoidea sp. B ---------------------------------- R 

Derbyia cf. D. robusta (Hall)------------------------ X 

Orthotetoid, gen. and sp. indet ----------------------- R 

Echinoconchus s.p. A -------------------------------- R 

Antiquatonia cf. A. coloradoensis (Girty) ------------- C 

Linopro,ductus eastoni n. sp -------------------------- R 

Linorproductus planivent'ralis Hoare ------------------ X 

Cleiothyridina sp ----------------------------------- R 

Composita ovata Mather ----------------------------- C 

Composita elongata Dunbar and Condra) _____________ X 

Anthrac.ospirifer occiduus ( Sadlick) ----------------- C 

Anthracospirifer rawlinsensis n. sp ------------------- X 

RANCHESTER LIMESTONE MEMBER 

Thirty-six collections containing brachiopods from 

the Ranchester Limestone Member have been 

studied. These are distributed in six counties. The 

brachiopods range in age from very late Chesterian 

(Late Mississippian) to Atokan (Middle Pennsylvanian), the Mississippian ones being restricted to 

western Wyoming. 

Lincoln County.-The oldest beds of the Ranchester Limestone Member were recorded in the Moffat 

Trail and Covey Cutoff sections ( collns. 82, 95-98) 

and contained these brachiopods. 

Pulsia s,p. A ---------------------------------------- R 

Eolissochonetes pseudoliratus (Easton)? -------------- R 

lnflatia lovei n. sp? --------------------------------- X 

Pugnoides quinqueplecis Easton ---------------------- R 

Com.posita sigma n. sp ------------------------------- C 

Anthra.cospirifer shawi exoletus n. subs.p -------------- R 

Anthracospirifer welleri lincolnensis n. suhsp ---------- C 

This assemblage, of undoubted Mississippian age, 

appears to correlate with the upper fauna of the 

Horseshoe Shale Member in Fremont County, despite 

the fact that the foraminiferal determinations indicate a slightly earlier age (Zone 18) than the beds 

on Berry Creek. 

Higher beds in the same two sections and at Peak 

9837 (collns. 83-87, 89, 99-101) carry a fauna of 

Early Pennsylvanian (Morrowan) age. 

Schizophoria depressa Easton ------------------------ X 

Rhipidomella carbona'ria (Shumard) ----------------- C 

Orthotetes sp. A? ----------------------------------- X 

Orthotetoid, gen. and sp. indet ----------------------- R 

Ru.goclostu.s willia.msi n. sp -------------------------- X 

Juresania sp --------------------------------------- R 

Antiquatonia blackwelderi n. s.p ---------------------- X 

Linoproductus eastoni n. sp? ------------------------- R 

Composita ovata Mather? ---------------------------- R 

Composita s1p. indet__________________________________ X 

Anthra.cospirifer occiduus ( Sadlick) ------------------ X 

Characteristic of this fauna are the productoids 

Rugoclostus williamsi, Juresania sp., Antiquatonia 

blackwelderi, and the spiriferid Anthracospirifer 

occiduus. 

Sublette County.-Only two collections are available from this county, and both of them are of 

Pennsylvanian age; it is not known whether or not 

the basal part of the member includes beds of 

Mississippian age. The collections from Tosi Ridge 

and Hodges Peak ( collns. 133, 134) represent the 

Antiquatonia blackwelderi assemblage. 

Orbiculoidea sp. B? --------------------------------- R 

Eolissoc.honetes pseudoliratus (Easton) --------------- A 

Juresania sp --------------------------------------- R 

Anf'iquatonia blackwelderi n. sp ---------------------- X 

Linoproductus eastoni n. sp -------------------------- X 

Anthracospirifer occiduus (S,adlick) ------------------ R 

Teton County.-Two collections from the lower 

part of the member on the west slope of the Teton 

Range, at Glory Mountain and Darby Canyon 

(collns. 146, 148), contain an Anthracospirifer 
D14 THE AMSDEN FORMATION (M.IS:SISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

closely related to the one in the Horseshoe Shale 

Member at Berry Creek, and the associated fauna 

indicates a Mississippian age. The brachiopods at 

these localities are as follows: 

Orbiculoidea wyomingensis (Branson and Greger)? ____ R 

Orthotetoid, gen. an dsp. indet ------------------------ X 

Composita sigma n. sp ------------------------------ X 

Anthracospirifer aff. A. occidnus (Sadlick), form B ____ C 

Eumetria sulcata Burk ------------------------------ X 

At Elk Ridge on the north end of the Teton 

Range, the lower limestone unit of the Ranchester 

Limestone Member (colin. 160) contains two brachiopod species of Mississippian age-Composita 

sigma n. sp. and Anthracospirifer shawi exoletus n. 

subsp. 

Most of the Ranchester in Teton County is Pennsylvanian in age. The Antiquatonia blackwelderi assemblage appears for the first time fairly low in 

the member; fossil collections from localities at 

Hoback Canyon, Granite Creek, Darwin Peak, Black 

Peak, and Pyramid Peak ( collns. 130, 131, 136, 139-

143) contain the following brachiopods: 

Lingula cf. L. carbonaria Shumard____________________ R 

Schizophoria aff. S. texana Girty --------------------- R 

Orthotetoid, gen. and sp. indet ----------------------- X 

Eolissochonetes pseudoliratus (Easton) _______________ C 

Juresania sp --------------------------------------- R 

Antiquatonia blackwelderi n. sp ---------------------- X 

Linoproduc,tus eastoni n. sp ------------------------- X 

Cleiothyridina sp ----------------------------------- R 

Composita o'Vata Mather ----------------------------- X 

Composita elongata Dunbar and Condra ______________ R 

Composita subtilita (Hall) ______ -------------------- X 

Anthracospirifer occiduus (S.adlick) __________________ R 

Shwridan County.-In. the type region of the 

Amsden Formation, all the fossils studied are of 

Morrowan age and have come from the Ranchester 

Limestone Member, where they occur silicified in 

impure limestone beds. The fauna from three localities on Amsden Creek ( coHns. 63, 67, 68) is as 

follows: 

Schizophoria depressa Easton ------------------------ R 

Schizophoria aff. S. texana Girty --------------------- C 

Eolissochonetes pseudoliratus (Easton) ---'------------ R 

Antiquatonia cf. A. coloradoensis (Girty) _____________ R 

C01nposita ovata Mather? ------------------------ ____ R 

Cotnposita sp. indet --------------------------------- R 

Johnson Cmlnty.-The only Ranchester fossils 

from this county came from a calcareous sandstone 

bed near the top of the member (colin. 52) , on 

North Fork, Crazy Woman Creek. This brachiopodmollusk faunule is the one upon which Darton (1906, 

p. 33, '34) first based the Pennsylvanian age of the 

upper part of the Amsden Formation. The brachiopods, as reidentified in the present report, are as 

follows: 

Pulsia delira n. sp ---------------------------------- R 

Juresania sp --------------------------------------- R 

Anthracospirifer? sp. indet -------------------------- R 

Whether the beds at this locality are late Morrowan 

or early Atokan in age is not presently known. 

Carbon County.-Four collections from the Ranchester Limestone Member in this county include 

rocks of both Morrowan and Atokan age. Those of 

Morrowan age are from the Meadow Ranch and 

Buck Spring sections (collns. 13, 14) and include 

the following brachiopods: 

Schizophoria aff. S. texana Girty --------------------- X 

Scoloconcha globosa (Mather) ----------------------- R 

Echinoconchus sp. A -------------------------------- R 

Antiquatonia cf. A. coloradoensis (Girty) -'------------- X 

Composita ovata Mather ---------------------------- A 

Anth1·acospirijer occiduus (Sadlick), var -------------- R 

The Morrowan age of this faunule is confirmed by 

Foraminifera found in the same beds. 

A faunule of Atokan age was recorded on U.S. 

Highway 287 near Rawlins and at Belle Springs 

( collns. 6, 15) . Most of the species occur also in 

the beds of Morrowan age. 

Derbyia cf. D. robusta (Hall)? ---------------------- R 

Mesolobus sp --------------------------------------- R 

Echinoconchus sp. A -------------------------------- R 

Antiquatonia cf. A. coloradoensis (Girty) ------------- C 

Linoproductus planiventralis Hoare ------------------ X 

Composita subtilita (Hall) -------------------------- C 

Anthracospirifer occidu.us (Sadlick) ------------------ X 

This faunule is regarded as Atokan in age because, 

despite the similarity of most of the brachiopods to 

those of known Morrowan age in the eastern areas 

of Amsden outcrop, the faunule contains M esolobus, 

a genus that is restricted to rocks of Atokan and 

Des Moinesian age. Foraminifera in the same beds 

confirm their Atokan age. 

ZONAL DISTRIBUTION OF THE BRACHIOPODS 

In table 4 the stratigraphic distribution of 57 

Amsden brachiopods is equated with the occurrence 

of foraminiferal zones and coral assemblages. Also 

shown, by numbers following each species, is their 

presence in three geographic regions: western, westcentral, and east-central Wyoming, the last including 

the Rawlins hills. Western Wyoming includes Lincoln, Sublette, and Teton Counties; west-central 

Wyoming is restricted to Fremont County, and eastcentral Wyoming includes Sheridan, Johnson, 

Washakie, and Carbon Counties. A glance at this 

chart will show that the brachiopods have considerable use biostratigraphically. 

For the purpose of biostratigraphic correlation, as 

discussed by Sando, Gordon, and Dutro (1975), 

several faunal zones have been recognized. Some 

of these zones, at least in the Mississippian rocks, 
BRACHIOPODA OF THE AMS.DEN FORMATION D15 

have different boundaries from the foraminiferal 

zones of Mamet and so, in combination, permit a 

relatively detailed breakdown of the stratigraphic 

section. Table 5 lists the megafauna! zones which 

are recognized within the Amsden Formation of 

Wyoming. 

Although no single section contains all the zones, 

their superposition in this order seems assured. 

Pennsylvanian zones have not been differentiated 

in northeast-central Wyoming (Sheridan, Johnston, 

and Washakie Counties) , but several localities there 

contain Zone 20 Foraminifera, indicating Morrowan 

age. The subject of faunal zones is discussed more 

fully by Sando Gordon, and Dutro (1975). 

TABLE 4.-Stratig?·aphic distribution of Amsden brachiopods equated with foraminifer zones and coral occurrences 

Age ~~~i;:·J Coral occurrences zones Orthotetoid 

brachiopods Productoid 

brachiopods 

Composita Anthracospirifer I Other brachiopods 

l=l 

'II 

'j:l 

'II 

> 'S 

l=l 

~ 

<II 

P-t 

l=l 

'II 

·p, 

:I 

~ 

~ 

~ 

·a 

~ 

> 

• I 'II 

I I 

I Antiqnat.,.ia d. A.l .!<: 21 Derbyia cf. D. robusta J coloradoensis 1 .s Linoproductus < planiventralis 

N eokoninckoph yllum 

hamatilis 1 

l=l 

'II 

~ 20 0 

'"' ::.. 

0 

~ 

amsdenensis 2 

19 I BarytiahU.ma 

l=l 

'II 

·;::: 

~ 18 <II 

.c Chaetetes wyoming- Q ensis 3 

M ultithecopora? 

amsdenensis 3 

Duncanopora 

duncanae 3 

--- Pleurosiphonella 

drummondi 3 

Caninia cf. C. 

nevadensis 3 

Lonsdaleia (Actinocyathus) stelcld 3 

17 

1 Occurs in east-central Wyoming. 2 Occurs in west-central Wyoming. 3 Occurs in western Wyoming. 

I 

Pulsia delira 2 

Antiquatonia cf. A. coloradoensis 1 

Linoproductus 

planiventralis 1 

Scoloconcha 

Derbyia cf. D. robusta J globosa 2 

Echinoconchus sp. A 1 

Juresania sp. 2 3 

Antiquatonia Orthotetes B]J. A 13 blackwelderi 3 J,inoproductus eastoni 13 

Rugoclostus 

williamsi 3 

sis bransonorum 2 3 

Orthotet" kaakaakien-~ Ovatia croneisi? a 

Orthotetina ams- Ovatia croneisi 2 

denensis 2 

Orthotetes kaskaskien- Ovatia muralis 2 :J 

sis bransonorum 2 

Carlinia (J,ms- Schuchertella deniana 2 

poposiensis 2 lnflatia lovei 2 

Flexaria sp.2 

Diaphragmus nivosus 3 

Pulsia sp. A 3 Inflatia lovei 3 

Antiquatonia sp.3 

Diavhragmus cestriensis 3 

Orthotetes sp. 3 Ovatia muralis 3 

TABLE 5.-Coral and brachiopod z·ones of the .4msden 

Forma.tion of Wyoming 

Age Zone 

Atokan M esolobus Zone 1 

I 

c. ovata 1 

lA I c. subtilita 1 occiduus 1 Mesolobus sp.l 

Rhipidomella carbonaria 3 

A. 1·awlinsensis 1 

C. ovata ~ Orbiculoidea sp. B 1 

c. elongata1 3 A. occiduus 1 a Schizophoria aff. S. texana 13 

c. subtilita 3 

Schizophoria depressa 2 3 

Eolissochonetes 

vseudoliratus a 

C. sigma 3 I A. aff A. I Eolissochonetes 

occiduus 2 3 pseudoliratus 3 C. sulcatn 2 A. shawi exoletus 2 a Pugnoides quinqueplecis 2 a 

c. poposiensis 2 A. 1velleri lin- Orbiculoidea wyomingensis 2 

colnensis 3 Eumetria sulcata 2 3 

c. poposiensis 2 A. shawi shawi 2 3 Orbiculoidea wyomingensis 2 

(early form) Orbiculoidea sp. A 2 

Schizophoria depressa 2 

.tl. toelleri welleri 2 Schizophoria aff. S. texana 2 

c. sigma 2 :J Cleiothyridina hirsuta 

darwinensis 2 

Reticulariina browni 2 

Eumetria. sulcata 2 

Brachythyrina Schizophoria depressa 3 

washakiensis a Cleiothyridina atrypoides 

saginata a 

Neospirijer 

C. subquadrata 3 praenuntius 3 

A. curvilateralis 3 Colcdium fragum s 

C. aff. C. laevis 3 A.. c. brutus 3 

ANALYSIS OF FAUNAL RELATIONSHIPS 

>. 

The brachiopod study has turned up facts as to 

taxonomic similarities and differences, geographic 

distribution, stratigraphic succession, relative abundance, and various habitats of the fauna. Let us now 

briefly review the fauna by major groups, discuss 

the implications of these facts, and interpret some 

of the faunal relationships and their bearing upon 

the depositional history of the Wyoming basin. 

Ul 

§ Morrowan N eokoninckophyllum hamatilis Zone 1 

Q) 

0.. A ntiquatonia blackwelderi Zone 3 

~ Anthracospirijer 'WelleTi-shawi Zone 2 ~ ~ 

·a Chesterian Composita poposiensis Subzone ~ 2 

·;n 

Ul 

Carlinia amsdeniana Subzone 2 ·;n 

Ul 

~ Caninia Zone 3 

1 Southeast-central Wyoming. 2 Centlral Wyoming. 3 Western Wyoming-Teton, Lincoln, and Sublette Counties. 

Table 4 indicates that most of the brachiopods 

have rather limited stratigraphic ranges. Most of 

them occur rather sporadically and with a few exceptions do not reveal any evolutionary trends. The 

few exceptions are the Orthotetes-Derbyia succession and the very abundant genera Composita and 

Anthracospirifer, which account, in numbers of individuals, for more than two-thirds of our collections. 
D16 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

INARTICULATES 

As one would suspect, the long-ranging and fairly 

stable genera Lingula and Orbiculoidea provide relatively little of stratigraphic value. The species identified as Lingula cf. L. carbonaria Shumard is found 

in both the Mississippian and the Pennsylvanian 

parts of the formation. However, Orbiculoidea wyomingensis Branson and Greger and the very excentric 0. sp. A are restricted to the Anthracospirifer 

welleri-shawi Zone, whereas a third species 0. sp B 

occurs in the N eokoninckophyllum hamatilis Zone. 

ORTHIDS 

Two species of Schizophoria, S. depressa Easton 

and S. aff. S. texana Girty, have fairly long ranges 

anc are found on both sides of the MississippianPennsylvanian boundary. The ubiquitous Pennsylvanian species Rhipidomella carbona1·ia (Swallow) 

was found in a single bed in the Morrowan part of 

the section. 

ORTHOTETOIDS 

Eight species belonging in five genera occur in the 

Amsden. The Meekellidae are represented by Puls,ia 

sp. A in the Caninia Zone and overlying Anthracospi1·ifer welleri-shawi Zone in western Wyoming, 

by Orthotetina amsdenensis (Branson and Greger) 

in the Carlinia amsdeniana Subzone in west-central 

Wyoming, and by Pulsia delira n. sp. in Pennsylvanian rocks near the top of the formation in eastcentral Wyoming. 

Schuchertella popos1~ensis (C. Branson) occurs in 

west-central Wyoming, presumably in the Carlinia 

amsdeniana Subzone. 

The Orthotetidae are represented by the somewhat 

aberrant shell having a fairly high interarea, described as Orthotetes sp., in the Caninia Zone and 

the low interarea form 0. kaskaskiensis bransonarum n. subsp. in the Anthracospin:fer welleri-shawi 

Zone. An evolutionary trend that involves the diminution in size of the spondylium in the pedicle 

valve and a change to multicostellate sculpture gives 

rise to 0. sp. A in the Eady Pennsylvanian Antiquatonia blackwelderi Zone. This species is probably the same Orthotetes that occurs in the Cameron 

Creek Member of the Tyler Formation and Alaska 

Bench Limestone in south-central Montana. The 

latest species of this family in the Amsden is Derby1:a cf. D. robusta (Hall), which is very c:lose to the 

typical midcontinent form. 

CHONETIDS 

Besides Eolissochonetes? suttoni (C. Branson), 

which cannot be recognized because its internal 

characters are not known, the only chonetid in the 

Mississippian part of the formation is E. pseudoliratus (Easton), which appears in western Wyoming near the top of the Anthracospirifer wellerishawi Zone and continues across the MississippianPennsylvanian boundary into the Antiquatonia 

blackwelderi Zone. In the Rawlins hills, an early 

form of Mesolobus characterizes a faunule of early 

Atokan age. 

PRODUCTOIDS 

Sixteen species of productoid brachiopods belonging in 11 genera have been recognized in the Amsden. The genera lnfiatia, Flexaria, Diaphragmus, 

Carlinia, and Ovatia are restricted to the Mississippian part of the formation. Scoloconcha, Rugoclostus, Juresania, Echinoconchus, and Linoproductus 

have been found only in the Pennsylvanian part. 

Elsewhere, however, Scoloconcha and Echinochonch-zts occur in rocks of Mississippian age. Antiquatonia has been recognized in both parts of the formation. 

Among the Marginiferidae, lnfiatia lovei n. sp., 

which occurs in the older part of the Horseshoe 

Shale Member and in the Anthracospirifer wellerishawi Zone, is replaced by the lnfiatia-like Rugoclostu,s williamsi n. sp. in the Pennsylvanian Antiquatonia blackwelderi Zone. 

Among the Productidae, Diaphragmus cestriensis 

(Worthen), which occurs in the Caninia Zone, is a 

characteristic midcontinent species. D. nivosus n. 

sp. is known elsewhere only in the Heath Formation 

of south-central Montana. Carlinia amsdeniana Gordon, which characterizes the subzone of the same 

name, seems to be an endemic species. 

Antiquatonia blackwelderi n. sp. occurs a~so in the 

Wells Formation of Idaho. In the eastern part of the 

Amsden outcrop it is replaced in beds of Morrowan 

age by A. cf. A. coloradoensis (Girty). No brachiopod collections are available from beds of Pennsylvanian age in the intervening central part of Wyoming. 

RHYCHONELLOIDS 

Two rhynchonelloids in the Amsden Formation 

are the stenoscismatid Coledium fragum n. sp., from 

the Can1:nia Zone, and Puginoides quinqueplecis 

Easton, which is restricted to the C ompositia poposiensis Subzone of very Late Mississippian age. P. 

quinqueplecis was described originally from southcentral Montana and occurs there mainly in rocks of 

Pennsylvanian age. 

ATHYRIDS 

The genus Cleiothyridina includes five different 

forms, none of which seems identical to previously 
BRACHIOPODA OF THE AM8DEN FORMATION D17 

described forms. New subspecies have been erected 

for two of them. C. atrypoides saginata n. subsp. 

occurs in the older part of the Horseshoe Shale 

Member. C. hirsuta darwinensis n. subsp. is found 

fairly commonly in the Carlinia amsdeniana Subzone. A few specimens from the Caninia Zone were 

identified as C. aff. C. sublamellosa (Hall) and two 

from the Carlinia amsdeniana Subzone, as C. aff. C. 

elegans Girty. The few crushed Pennsylvanian speciments were not identifiable. 

The genus Composita is represented by eight 

species (fig. 1), two of them new though previously 

described under other names. The earliest one, the 

ubiquitous Chesterian species C. subquadrata 

(Hall), occurs in the Caninia Zone. Locally in the 

Horseshoe Shale Member, adjacent to the limestones 

of the Caninia Zone, is a small narrow form described as C. aff. C. laevis Weller. This species probably was ancestral to C. sigma n. sp., the most widely 

distributed Composita in the Anthracospirifer welleri-shawi Zone. C. sigma is the only Composita in 

the Carlinia amsdeniana Subzone in central Wyoming; in the overlying subzone it is superseded by its 

descendant C. poposiensis and by C. sulcata Weller, 

a characteristic midcontinent species. These last two 

species do not occur, however, in western Wyoming, 

where C. sigma continues to the top of the Mississippian. Little doubt exists that C. poposiensis was an 

offshoot of C. sigma, differing from it mainly in 

having three fairly deep sulci in the pedicle valve 

in the typical form. The C. sigma-C. popsiensis complex seems to be endemic to the Wyoming depositional basin. 

In the Morrowan part of the formation the compositas change abruptly, the typical species being C. 

ovata Mather, C. elongata Dunbar and Condra, and 

C. subtilita (Hall). They tend to be larger than the 

Mississippian forms. As these are widely distributed 

species in Pennsylvanian rocks of the United States, 

it is likely that they entered the Wyoming basin 

from the outside. Nevertheless, some similarities 

between C. sigma and C. ovata and a C. subtilitalike variant of C. poposiensis with C. subtilita raises 

the question whether the Pennsylvanian species may 

have been derived locaHy. 

SPIRIFERIDS 

The Spiriferidae are represented by seven species 

belonging in three genera. The most common are 

the five anthracospirifers, among which three of 

the species have been divided into two subspecies 

(fig. 2). They constitute a taxonomic succession of 

considerable biostratigraphic utility. The earliest 

ones, Anthracospirifer curvilateralis curvilateralis 

Easton and A. c. brutus n. subsp. occur in the 

Caninia Zone. It seems likely that A. c. curvilateralis 

was ancestral to A. welleri welleri and A. c. brutus 

to A. shawi shawi of the Carlinia amsdeniana Subzone. The early forms of the central Wyoming 

species have about the same number of ribs, respectively, as their Caninia Zone progenitors, but the 

shell shapes are different and the sizes smaUer. 

Once established as distinct species in the same 

environment, the central Montana anthracospirifers 

began further differentiation. In the Composita popsiensis Subzone, A. welleri is missing entirely, and 

A. shawi is represented by the more complex and 

slightly larger subspecies A. s. exoletus n. subsp. The 

descendants of A. welleri occur only in western 

Wyoming, where the subspecies A. w. lincolnensis 

is recognized. Some small specimens within local 

populations there are fairly close to typical A. 

wellerri welleri but are considered to belong within 

the range of variation of the western subspecies. 

In uppermost Mississippian rocks exposed at 

Berry Creek in the Teton Range, an interesting 

assemblage shows a lithofacia~l differentiation of 

the anthracospirifers. A. weller·i lincolnensis is abundant in limestone layers and is associated with rare 

A. shawi exoletus. Intervening layers of reddishgray shale are crowded with what appears to be an 

early form of A. occiduus, here described as A. aff. 

A. occiduus, form A. The early (pre-Pennsylvanian) 

occurrence of an occiduus-like shell indicates that 

this area may have been the cradle of that ubiquitous Pennsylvanian species. It is not clear, however, 

whether this form was introduced from outside the 

Wyoming depositional basin or whether it began 

here as a modification of A. shawi exoletus. A single 

specimen of A. aff. A. occiduus form A has been 

recognized in the Composita poposiensis Subzone in 

the Wind River Mountains. 

Typical A. occiduus is the dominant anthracospirifer in the Pennsylvanian part of the Amsden, occurring in rocks of both Morrowan and Atokan age. 

Another Pennsylvanian species) A. rawlinsensis n. 

sp., is found sparingly in beds of late Morrowan 

age in southeast-central Wyoming. This species has 

the greatest number of costae of all the Amsden 

anthracospirifers. Similar and perhaps conspecific 

shel.ls are known in the east-central part of the 

Great Basin. 

Other spiriferids include a shell fragment from 

the fringes of the Caninia Zone identified as N eospirifer praenuntius Easton and Brachythyr;·ina 

washakiensis n. sp. from the older part of the Horse-
D18 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

SYSTEM SERIES WESTERN WYOMING I WEST-CENTRAL WYOMING EAST-CENTRAL WYOMING 

MAMET 

FORAMINIFERA 

r---~---z--+-----------------------~------------------------~-------------------------h~ 

z 

<( 

z 

<( 

> ...J 

>-

CJ) 

z 

z 

w 

0.. 

<( 

~ 

0 

~ 

z 

<( 

~ 

0 

0:: 

0:: 

0 

~ C. subtihta, 

C. elongata, 

C. ovata 

1-----+------1----------------------

... (]) 

(])C"-

C. subtilita ~~~· 21 

..c(])E 

u E (]) t-------1 

~:i~ 0:: 

C. 'uhtilita. 

·~ ~ (])~ C. elongata, _g ~ 

){l~ 

C. ovata ~~ 

oro 

I..C (/) 

20 

-------------------·-/_-. 7.+-----i 

.Y 

C. sigma C. poposiensis, 

C. sulcata ... ·:.I 

... ::"/ 

. . ,.; .. :. 19 

z 

<( z 0::: <( 

0.. 0:: 

U5 LJ.J 

1- CJ) (/) 

U5 LJ.J 

~ I 

(.) 

~ 

-

... 

(]) 

.0 

=E 

til(]) 

~~ C. subquadrata +'(]) 

roc 

::=o 

Q+' 

~){l 

E 

:i 

............ 

. ·.: .. . · .. :·: .·. . ......... :::; ·.·· .... ·.:... . i 

...•......•...•... i:Urhlf•i 

C. sigma. .... . . · .. 

18 

17 

FIGURE !.-Distribution of Com.posita in the Amsden Formation. 

shoe Shale Member. Three specimens identified with 

question as Torynifer setiger Hall came from the 

Carlinia amsdeniana Subzone. 

The one member of the Spiriferinidae, Reticular·iina browni (Branson and Greger) is common in 

the Carlinia amsdeniana Subzone in Fremont 

County. At the only locality outside that county 

where it has been recorded, the containing bed was 

assigned to the Composita poposiensis Subzone. 

RETZIIDS AND TEREBRATULOIDS 

Eumetria sulcata Burk occurs in both the Ca'tlinia amsdeniana and Composita poposiensis Subzones. It seems to be very dosely related to the midcontinent species E. costata (Hall) and is regarded 

as a typical Mississippian species. Three specimens 

from the Carlinia amsdeniana Subzone are identified 

as Girtyella cf. G. indianensis (Girty). These are 

the only terebratuloids known from this basin. 

INTERPRETATION OF FAUNAL SUCCESSION 

Extension of the brachiopod zones across lithologic 

boundaries demonstrates rather clearly the eastward transgression of the Amsden Formation. The 

recognizable lithologic members of the Amsden 

become progressively younger eastward. The distribution of the compositas and anthracospirifers 

in the Amsden, shown diagrammatically in figures 1 

and 2, shows this relationship, particularly with 

regard to the Mississippian-Pennsylvanian boundary. This transgression is discussed fully by Sando, 

Gordon, and Dutro (1975). 

The relation of the fauna within the basin to the 

fauna of other basins indicates that several different periods or stages of faunal development took 

place. These changes in the fauna seems to be 

related to the tectonic and depositional history of 

the basin. 
BRACHIOPODA OF THE AMSDEN FORMATION Dl9 

I I 

MAMET 

WEST-CENTRAL WYOMING EAST-CENTRAL WYOMING FORAMINIFERA ~---+--z--~------------------------L-----------------------~--T~~--------------------~-(])~~ZONES; 

SYSTEM SERIES WESTERN WYOMING 

~ (])c 

~ tl .8 Qj 21 0 (])~~ ~ ~(])E 

~ gE(]) 

z 

<( 

z 

<( 

> ....J 

:> 

(/) 

z 

z 

w 

0... 

z 

~ 

3: 

0 

a::: 

a::: 

0 

~ 

A. occiduus 

1------+------1------------------

A. aff.A. oc6duus, form A, 

A. shazm: exoletus, A. welleri l·incolnensis 

~ :::; ~ ,__ __ --I 

A~occiduus ~~ 20 

~(]) 

A. rawlinsensis ~ ~ 

0~ 

I~ (/) 

I; ------·- --------------,..+--____, 

A. shaw1: exoletus 19 

A. welleri lincolnensis .. ·. ... 

A. shawi shawi, . .. . : ·/ 

A. wellen welleri · :.:- · · _->· 

z 

~ 

a:: 

w 

~ 

(/) 

w 

I 

(.) 

A. curvilateralis 

cu rvilateral is 

A. curvila.teralis 

brutus .· ....•.... ·· .•...• · .. ·.•·.••·· ,o"''"'; s•"~,o:~ebe;: • •• <o .. " 

18 

..... _ ...... ·· . • • • • •• • •• 0 

... ·.··· ....... . 17 

.. . . .. . . · .. · .......... -:· 

...... ···· •••• •••••• • •• •• ••• •• 0 

•• •• ~ • • 0 

:,}i\········~ FIGURE 2.-Distribution of Anthracospiri.fer in the Amsden Formation. 

The earliest brachiopod assemblage is found in 

and around the Caninia Zone coralline facies that 

stretched from western Montana southward to 

western Utah. The corals are widely distributed, 

the same few species occurring at many different 

localities. The brachiopods, however, are more local 

in distribution. Several American midcontinent 

species, including Diaphragmus cestriens1~s (Worthen) and Composita subquadrata (Hall) are present 

in this part of the Amsden in western Wyoming. 

Also present in the coralline facies or in nearby 

calcareous mudstones are several species common 

to the Heath Formation of south-central Montana, 

including Diaphragmus nivosu.s n. sp. and Anthrocospi'rifer curvilateralis (Easton). 

The fauna of the Anthracospirifer welleri-shawi 

Zone and its subzones in the Horseshoe Shale Member in Fremont County is almost entirely endemic. 

Such species as 01·thotetina amsdenensis (Branson 

and Greger), Schuchertella poposiensis (C. Branson), lnfiatia lovei n. sp., Carlinia amsdeniana Gordon, Composita sigma n. sp., C. poposiensis n. sp., 

Anthracospi1·ijer welleri (Branson and Greger), 

A. 8hawi n. sp., and Reticulariina browni (Branson 

and Greger) are not known outside this depositional 

basin. The one exception is the presence in Fremont 

County of the mid-continent species Composita sulcata Weller in the C. poposiensis Subzone. As this 

form is not known in contemporaneously deposited 

beds in western Wyoming or in earlier Mississippian 

beds in Fremont County, its sudden appearance late 

in the development of an endemic fauna is puzzling. 

Nevertheless, as C. sulcata has been identified in the 

Upper Mississippian of Idaho (Girty, 1927, p. 64) 
D20 THE AM8DEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

and south-central Montana (Easton, 1962, p. 77), 

one can surmise that it already was living somewhere in the Wyoming depositional basin by the 

time the basin became isolated. The rest of the 

faunal evidence argues strongly for the presence 

of a relatively closed basin during the time span 

of the Anthracospirifer welleri-shawi Zone. 

Over much of western Wyoming during this time, 

conditions were not particularly suitable for the 

development of a large and varied fauna. The Ranchester Limestone Member contains many dolomite 

beds in this region, and the brachiopod fauna in 

this member is decidedly limited in variety. 

Early in Pennsylvanian time the west-central 

region became inhospitable to brachiopod populations. No brachiopod-bearing beds are known in 

Fremont County in this part of the Amsden Formation. The early Morrowan brachiopod faunas occur 

in two separate regions. In western Wyoming the 

fauna was dominated by Eolissochonetes pseudoliratus (Easton), Antiquatonia blackwelderi n. sp., 

Composita ovata Mather, and Anthracopirifer occiduus (Sadlick), and this fauna extended into the 

Idaho region. The similar fauna in east-central 

Wyoming contains Antiquatonia cf. A. coloradoens1:s 

(Girty) and Linoproductus eastoni n. sp., which are 

also typical of the Cameron Creek Member of the 

Tyler Formation and Alaska Bench Limestone of 

south-central Montana. This and the lithologic 

evidence indicate that the barrier between the Wyoming and south-central Montana basins aws 

breached early in Morrowan time, allowing some 

of the faunal elements to comingle. 

Further links, during Morrowan and Atokan time, 

of the Wyoming depositional basin with basins to 

the east and southeast permitted the introduction 

to Wyoming of such midcontinent species as Scoloconcha globosa (Mather) and Linoproductus planiventralis Hoare. 

In summary, the depositional and faunal successions in the Late Mississippian and Early to 

Middle Pennsylvanian in Wyoming involved1. A Mississippian brachiopod fauna of rather 

mixed origins in a predominantly coralliferous 

facies during the early stages of the transgression. 

2. Development of an almost totaHy endemic Mississippian fauna as the transgressive locus of 

deposition extended farther east and the basin 

remained virtually closed. 

3. Assembling of a Pennsylvanian fauna again of 

rather mixed origins as the basin began to 

link up to the northeast, east, and southeast 

with other depositional basins. 

SYSTEMATIC PALEONTOLOGY 

Phylum BRACHIOPODA 

Class INARTICULATA 

Order LINGULIDA 

Superfamily LINGULACEA Menke 

Family LINGULIDAE Menke 

Genus LINGULA Bruguiere, 1797 

Lingula cf. L. carbonaria Shumard 

Plate 1, figures 1-3, 6 

Lingula carbmwria Shumard, 1858, p. 215. 

Lingula cf. L. carbonaria Shumard. Eas·ton, 1962, p. 38, pl. 

4, fi·g. 12. 

Lingula is rare in collections from the Amsden 

Formation of Wyoming; our material aggregates 

eight specimens from four localities. Three are 

from limestone beds of Early Pennsylvanian (Morrowan) age in the Ranchester Limestone Member 

in the Gros Ventre Range, western Wyoming. These 

are moderate sized, the largest (pl. 1, figs. 2, 3) 

measuring 13.5 mm long and 8. 7 mm wide. Another lot of five specimens is from siltstone of Late 

Mississippian age in the Horseshoe Shale Member 

at Wiggins Fork, Washakie Range (pl. 1, figs. 1, 

6). They are smaller than the Pennsylvanian specimens, the most complete valve measuring 7.3 mm 

long and 4.6 mm wide. All are regarded as belonging 

in the same species. 

The shells are elliptical, having the greatest width 

near the middle of the valve. Those preserved in 

limestone commonly have a somewhat elevated urnbona! region, whereas those preserved in siltstone 

are nearly flat. The surface of both valves is marked 

by fine regular concentric striae. 

These shells have the same width-length ratios 

as, and appear to be conspecific with, specimens 

identified by Easton (1962, p. 38) as Lingula cf. L. 

carbonaria from the Heath Formation, Cameron 

Creek Formation, and Alaska Bench Limestone of 

south-central Montana. They have somewhat less 

acute apical angles than examples of L. carbonaria 

figured by Dunbar and Condra (1932, pl. 1, figs. 1, 

2) from the Pennsylvanian of Nebraska but agree 

rather closely with specimens from the Pennsylvanian rocks of Missouri identified as L. carbonaria 

by Girty (1915, p. 303), with which they have been 

directly compared. 

Figu.red specimens.-VSNM 163703A, B; 163704. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collection 46 ( 5), Fremont Cmttnty. 

Ranchester Limestone Member: collections 139! (1), 

141 (1), 142 (1), Teton County. 
BRACHIOPODA OF THE AMSDEN FORMATION D21 

Order ACROTRETIDA 

Suborder ACROTRETIDINA 

Superfamily DISCINACEA Gray 

Family DISCINIDAE Gray 

Genus ORBICULOIDEA D'Orbigny, 1847 

Orbiculoidea wyomingensis Branson and Greger 

Plate 1, figures 9, 11-16 

Orbiculoidea wyomingensis Branson and Greger, 1918, p. 314, 

pl. 19, figs. 7, 8; C. C. Branson, 1937, p. 655, pl. 89, fig. 

34; Easton, 1962, p. 39, pl. 4, fig. 13. 

Description.-Shell of moderate size, resupinate, 

subcircular; length slightly greater than width. 

Brachial valve depressed, asymmetrically subconical; apex excentric, 35 to 45 percent of distance 

from posterior to anterior margin; posterior slope 

shallowly concave in profile; anterior and lateral 

slopes convex. Surface of valve nearly smooth, with 

very fine concentric growth lirae and some scattered 

coarser lirae; radial sculpture of fine striae, visible 

both on inner and outer surfaces of shell and strongest where shell appears partly decorticated. No 

internal structures seen on internal molds. 

Pedicle valve shallowly convex posteriorly (concave posteriorly in lectotype probably because of 

crushing) and concave anteriorly. Apex excentric 

to subcentral; valve cleft posterior to apex by 

rather prominent foramen extending to within 2-3 

mm of posterior margin. Surface sculpture of concentric lirae with considerably wider interspaces, 

of which 8 to 12 occur in space of 2 mm. Radial 

striae also present in pedicle valve but less visible 

than on brachia1l valve. 

Dimensions.-Hypotype (USNM 163705) measures: length 13.3, width (not quite complete) 10.5, 

thickness (both valves) 4.5 mm. This is a relatively 

uncrushed but slightly asymmetrical specimen. 

Discussion.-Easton (1962, p. 39) redescribed the 

"cotypes" (UM 2641) and designated as the "bolotype" [lectotype] "the ventral valve figured by 

Branson and Greger (1918, pl. 19, fig. 7) ." It should 

be added that this pedicle valve is articulated with 

a brachial valve, so the lectotype is actually a nearly 

complete specimen. Both valves of this specimen 

are figured here (pl. 1, figs. 14-16), as is the paralectotype (pl. 1, fig. 9), a brachial valve also illustrated by Branson and Greger (1918, pl. 19, fig. 8). 

The primary types are from the Carlinia amsdeniana Subzone and are preserved in limonitic claystone. The specimen from the Composita poposiensis 

Subzone is partly silicified and preserved in sandstone. That this species may range up into the Lower 

Pennsylvanian locally is indicated by its identification by Easton (1962) in the Alaska Bench Limestone of the Big Snowy Range, Mont., from a poorly 

preserved specimen. 

Types.-Lectotype and paralectotype, UM 2641; 

hypotype, USNM 163705. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 36a, (2), 38 (1), Fremont 

County?; 146(1) Teton County. 

Orbiculoidea sp. A 

Plate 1, figur,e,s 4, 5, 10 

Lingulodiscina s,p., Burk, 19,54, p. 8, 9, pl. 1, figs. 13, 14. 

Four brachial valves, collected in the Wind River 

Range, were described by Burk (1954) who regarded 

them as belonging in Lingulodiscina, an imperfectly 

understood genus of phosphatic-shelled brachiopods. 

The specimen with the most complete margins (IT184) is 15.5 mm long and 15 mm (estimated) wide 

and 2.5 mm deep; the tip of the beak is 2.5 mm 

from the posterior edge. On another fragment (IT186) the distance of the beak from the posterior 

edge appears to be the same. It seems reasonable to 

regard these as a species of Or·biculoidea with its 

apex situated close to the margin. In two specimens 

the apex appears marginal, but in both of them 

the posterior edge of the she1l is broken away. In 

one (IT-185) the break shows that the shell is made 

up of 9 or 10 alternating light and dark laminae. 

The shells are worn, and two of them (IT-185, 

186) have shallow dendritic channeling on the surface, apparently made by some tiny organism. Local worn vestiges of concentric lirae are visible, 

but no radial triae or wrinkles such as are typical 

of 0. wyomingensis are present. 

The nearly marginal apex and absence of radial 

sculpture distinguish it easily from 0. ~vyomingens1:s. I agree with Burk (1954, p. 9) that this probably is an undescribed species, but the material is 

not sufficient to constitute a firm basis for erecting 

a new name. 

Figur·ed specimens.-VW IT-184, 185. 

Mentioned specimen.-VW IT-186. 

Occurrence and nurnber of specimens.-Horseshoe 

Shale Member: collection 21 ( 4), Fremont County. 

Orbiculoidea sp. B 

Plate 1, figure's 7, 8 

A brachial valve from the Ranchester Limestone 

Member in the Rawlins hills represents a third 

species of Amsden 01·biculoidea. It has a moderately 

large and deep shell with a slightly excentric umbo. 

The shell approximately is circular (slightly distorted by flattening along the posterior and posterolateral parts of the margin), 20.6 mm in longitudinal 

and transverse diameters, and 7 mm high. In lateral profile it is asymmetrical, the anterior slopes 

straight, becoming concave near the umbo and con-
D22 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

vex posterior to it; the umbo is 9 mm from the 

anterior edge, and the greatest depth is approximately at the center of the valve, a little behind 

the umbo. 

Surface sculpture consists of fine concentric lirae, 

about 10 of which occur in the space of 1 mm. 

Some of the lirae, more or ,Jess evenly spaced among 

the others, are coarser and some of these are dichotomous. 

From 0. wyomingensis this species is distinguished by its higher brachial valve, more centrarlly 

located umbo, coarser interspersed concentric lirae, 

and lack of radial striae. From 0. sp. A the much 

deeper brachial valve and lack of a nearly marginal 

umbo are easily distinguished differences. 

Figured specimen.-VSNM 163706. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collection 3 (1), Carbon County, 

Ranchester Limestone Member: collection ?134 (1), 

Sublette County. 

Class ARTICULATA 

Order ORTHIDA 

Suborder ORTHIDINA 

Superfamily ENTELET ACEA Waagen 

Family ENTELETIDAE Waagen 

Genus SCHIZOPHORIA King, 1850 

Schizophoria depressa Easton 

Plate 1, figures 17-19 

Schizophoria swallovi (Hall)? Branson and Greger, 1918, 

p. 312, 313, 321, pL 19, figs. 12, 13; C. C. Branson, 

1937, P'· 65-2. 

Schizophoria depressa Easton, 1962, p. 85, 86, pl. 4, figs. 

19-23. 

This species can be recognized by its broadly oval 

outline and its depressed cross section owing to the 

low convexity of the brachial valve, unusal in this 

genus. The hinge line is moderately long, equal to 

about three-quarters the length and almost threefifths the width of the shell in the specimen figured ; 

the cardinal angles are broadly obtuse, the hinge 

meeting the posterolateral margins of the shell at 

an angle of approximately 140° in the same specimen. About 18 radial lirae occur in the space of 5 

mm on the anterior slope near the margin. Easton 

has described this species in detail, and the reader 

is referred to his paper for further information. 

The figured specimen has the following measurements (in mm) : ~length 12.2, width 16.5, thickness 

7.6, depth of pedicle valve 3.2, depth of brachial 

valve 5.1, length of hinge 9.5, height of interarea 

in pedicle valve 1.7, and in brachial valve 1.1 mm. 

S. depressa is rare in the Amsden Formation, but 

occurs in beds both of Late Mississippian and Early 

Pennsylvanian age. Easton (1962, p. 85) placed in 

synonymy with this species the specimen from 

Cherry Creek illustrated by Branson and Greger 

(1918, pl. 19, figs. 12, 13) as S. swallovi?. This is 

an iron-stained calcareous speeimen and probably 

came from the Carlinia amsdeniana subzone. Our 

specimen illustrated on plate 1 is from Livingston 

Ranch and came from the same subzone. Easton's 

Montana specimens were collected from beds of 

both Late Mississippian and Early Pennsylvanian 

age, but the holotype is from the Mississippian 

Heath Formation. 

Figured specimen.-VSNM 163707. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 36a (1), 45 (3), Fremont 

County; 41 (2), Teton County. Ranchester Limestone Member: collections 63 (2), Sheridan County; 

100 (8), Lincoln County. 

Schizophoria aff S. texana Girty 

Plate 1, figures 26·-30, 40, 41 

Description.-Shell inflated, resupinate; plane 

of commissure indented anteriorly by broad rounded 

sulcus; no corresponding fold identifiable. Pedicle 

valve subcircular to transversely suboval in outline, 

tending toward subpentagonal; greatest width a 

little anterior to midlength; convex in side profile, 

curvature greatest at beak and gradually lessening 

anteriorly; broadly convex in posterior profile with 

straighter sloping sides, slightly flattened over middle. Sulcus beginning approximately at midlength, 

broad and shallow anteriorly. Hinge roughly half as 

wide as valve; cardinal extremities forming obtuse 

angles. Interarea broadly triangular, inclined at 

roughly 150° to plane of commissure, approximately 

four times wider than high, concave in side profile, 

and pierced medianly by triangular delthyrium. Surface sculpture consisting of delicate capillae having 

subequal or slightly wider interspaces; 25 to 28 

capillae occurring in space of 5 mm near antetrior 

margin of shell. Concentric sculpture of several 

fairly prominent grooves, largely confined to anterior half of shell, representing brief interruptions 

in growth. 

Interior of pedicle valve having pair of dental 

lamellae diverging very slightly and bounding outer 

sides of rather narrow delthyrial chamber; musclescar field bisected by moderate-sized median septum. 

Sculptured anteriorly and laterally by prominent 

dendritic vascular grooves. Slightly denticulate 

along margin corresponding to capillae and interspaces of exterior surface. 

Brachial valve deeper than pedicle one, strongly 

convex subcircular to broadly oval in outline; fold 

not differentiated form rest of valve. Umbonal region inflated; beak strongly incurved and overhang-
BRACHIOPODA OF THE AMSDEN FORMATION D23 

ing hinge slightly. Interarea wide, shallow, concave. 

Sculpture similar to that of pedicle valve, but some 

capillae appearing larger than others spaced at 

fairly regular intervals. 

Interior of brachial valve having notothyral 

chamber bordered posterolateraJly by brachiophore 

bases that diverge at angle of 75°; muscle-scar field 

bisected by narrow sharp median ridge. Margin of 

valve denticulate. 

Dimensions.-lllustrated specimen measures (in 

mm) : length 15.5, width 19.1, thickness 12.2, depth 

of pedicle valve 5.5, depth of brachial valve 8.8, 

width of hinge 9.0, height of interarea in pedicle 

valve 2.2, and in brachial valve 1.5. 

Discussion.-As pointed out by Girty (1927, p. 

433) a marked efflorescence of Schizophoria seems 

to have taken place in Early Pennsylvanian time. 

At least six species are known in Lower Pennsylvanian rocks in the American midcontinent and 

west: Schizophoria altirost1·is (Mather), S. depressa Easton, S. oklahomae Dunbar and Condra, 

S. resupinoides (Cox), S. schucherti (Girty), and S. 

texana Girty. Actually this flowering of schizophorian species began in the latter part of the Late Mississippian species began in the latter part of the Late 

Mississippian as S. depressa, S. cf. S. resupinoides, 

and forms related to S. texana are locaLly abundant 

in upper Chesterian rocks in the Rocky Mountain 

and Great Basin regions. 

The Amsden species under consideration is somewhat like S. texana but differs from it in having a 

more convex pedicle valve with a more highly inclined interarea and incurved overhanging beak, and 

finer sculpture. These differences are even more 

accentuated when one compares the Amsden form 

with S. altirostris from the type Morrowan section 

in northwestern Arkansas. Mathers species has a 

much flatter pedicle valve, the n1edian sulcus already 

strongly developed at midlength in average specimens, markedly angular cardinal extremities, and 

a nearly flat interarea inclined at roughly 110° to 

the plane of commissure. The brachial valve is more 

highly arched transversely in S. alUrostris, the urnbona! region narrower and more elevated, and the 

flanks more obliquely planate. This species is easily 

distinguished from S. depressa Easton by its less 

transverse outline and much more convex brachial 

valve. 

This Amsden species is very close to the form 

that occurs in the Great Basin in western Utah and 

eastern Nevada in the same part of the section. 

There is very little difference in shape; however, 

Utah shells reach 23 mm in length and have slight<ly 

coarser sculpture, 15 to 19 capillae occurring in 

the space of 5 mm in the middle of the anterior 

slope. It seems likely that the western form is a 

distinct species, the Amsden specimens representing 

a subspecies of the Great Basin shells. In my opinion, 

the Great Basin species should be named first in 

order that more abundant and well-preserved specimens from a number of localities can be studied and 

serve as a basis for this taxon. For this reason I am 

not introducing a name at this time for the Amsden 

shells. 

Fig~l1·ed specimen.-USNM 163713-163715. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collection 45 (2), Fremont County. 

Ranchester Limestone Member : collections 13 ( 10) 

Carbon County; 67 (30), 68 (1), Sheridan County; 

141 (2), Teton County. 

Family RHIPIDOMELLIDAE Schuchert 

Genus RHIPIDOMELLA Oehlert, 1890 

Rhipidomella carbonaria (Swallow) 

Plate 1, figures 20-25 

Or·this carbonaria Swallow, in Shumard and Swallow, 1858, 

p. 218; Meek, 1872, p. 173, pl. 1, figs. Sa-c; Meek and 

Worthen, 1873, p. 571, pl. 25, fig. 4; Hall, 1883, pl. 

(7) 37, fi·gs. 1-4. 

Orthis pecosi White (not Marcou), 1877, p. 125, pl. 9, figs. 

5a-e; 1884, p. 129, pl. 3'2, figs. 20-22; Hall and Clarke, 

1892, pl. 7, figs. 1-4; Keyes·, 1894 [1895], p. 64; Smith, 

p. 237; 1897, p. 27. 

Rkipidornella pecosi (White). Beede, 1900, p. 96; Girty, 1903, 

p. 344; Woodruff, 1906, p. 279, pl. 10, fig. 4; Mark, 

1912, p. 303, pl. 13, fig. 10; Mather, 1915, p. 144, pl. 

8, figs. 3-3a; Morningstar, 1922, p. 175, pl. 7, fig. 13. 

Rhipidomella c,arbonaria (Swallow). King, 1930, p. 43; Dunbar and Condra, 1932, p. 52, pl. 2, figs. 1-4; Cooper, 

in Shimer and Shrock, 1944, p. 355, pl. 139, figs. 24-26; 

Plummer, 1950, pL 19, figs. 1a, b; Gehrig, 1958, p. 10, 

pl. 6, figs. 39-41; Hoare, 1961, p. 26, 27, pl. 1, figs. 

10-12; Sturgeon and Hoare, 1968, p. 25, pl. 2, figs. 13, 

14. 

Description.-Shell biconvex, pentagonally subcircular in outline; greatest width slightly anterior 

to middle; greatest thickness posterior to middle; 

hinge line equal to slightly less than half maximum 

thickness of shell. Pedicle valve less convex than 

brachial; beak moderately incurved over interarea. 

Interarea slightly wider than high, nearly flat but 

slightly concave in side profile; delthyrium moderately large, triangular with apical angle of about 

55°, open, occupying roughly two-fifths of interarea. 

Surface sculpture parvicostellate; costellae uneven, 

increasing by intercalation, about 16 occurring in 

space of 5 mm on anterior slope near margin. Shell 

minutely punctate. 

Pedicle interior with strong dental lamellae forming supports for teeth. Adductor muscle-scar plat-
D24 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

form elongate, elevated, nearly flat on top, located 

on floor of valve at base of slope beginning about 2 

mm in from umbo, in middle of depressed roundedsubtriangular diductor muscle-scar field and dying 

out at anterior end of this field; two small narrow 

closely spaced depressions near posterior end of 

adductor muscle-scar platform diverge posteriorly. 

Anterior and lateral margins of valve radically 

grooved internally. 

Brachial valve moderately -convex; greatest convexity near umbo; greatest depth near middle, and 

sloping toward margins. Interarea small, nearly flat, 

rudely crescent-shaped; notothyrium bordered by 

chilidium consisting of pair of nearly erect triangular 

plates diverging at angle of approximately 55°. Surface sculpture of brachial valve same as on pedicle 

valve. 

Interior of brachial valve with triangular cardinal 

process thrust between chilidial plates, set on large 

swollen posterior platform; process composed of 

short shaft supporting grooved myophore; posterior 

surface of myophore sloping anteriorly, generally 

marked by two prominent grooves and various finer 

lamellae; in some specimens short median groove 

separates above-mentioned two grooves anteriorly. 

Sides of cardinal process extend anterolaterally into 

brachiophores, also diverging at 55° angle, supported on floor of valve by base plates; hinge sockets 

occur between brachiophores and margin of valve at 

extremities of interarea. Median ridge, low and 

rounded, extends anteriorly from posterior platform, 

bisecting four muscle-scar depressions, a shallow and 

short posterior pair and a deep and subcircular 

anterior pair. Margins of valve radially grooved 

internally as in pedicle valve. 

Dimensions-Figured complete specimen (pl. 1, 

figs. 22, 25) measures: length 11.5, width 11.8, 

thickness 6.1, depth of pedicle valve 2.4, depth of 

brachial valve 3.2, length of hinge 4.5, height of 

interarea in pedicle valve 1.0, and in brachial valve 

0.6 mm. 

Discussion.-All the Pennsylvanian rhipidomellas 

have been put in a single species for which the 

synonymy is given above. Comparison with spe·cimens in the USNM collection shows some slight 

differences between the Wyoming specimens of Early 

Pennsylvanian age and specimens from the Finis 

Shale of Texas of Late Pennsylvanian age. The 

Finis Shale specimens are smaller, have a narrower 

interarea in the brachial valve, and a more delicate 

cardinal process. The Wyoming specimens seem to 

be identical with specimens of Early Pennsylvanian 

age from the Marble Falls Limestone near San Saba, 

Tex. 

This species is known in the Amsden Formation 

from a limestone bed in the Moffat Trail section, 

approximately 175 feet above the top of the Darwin 

Sandstone Member. It is the dominant fossil and 

only brachiopod in this bed. 

Figured specimens.-VSNM 163716-163718. 

Occurrence and number of specimens.-Ranchester Limestone Member: coUections 86 (12), 85 (18), 

Lincoln County. 

Order STROPHOMENIDA 

Suborder STROPHOMENIDINA 

Superfamily DA VIDSONIACEA King 

Family MEEKELLIDAE Stehli 

Genus ORTHOTETINA Schellwien, 1900 

Orthotetina amsdenensis (Branson and Greger) 

Plate 2, figures 1-3, 7; text figure 3B 

Meekella arnsdenensis· Branson and Greger, 1918, p. 318, pl. 

18, figs. 22-25. 

Diagnosis.-N on plicate meekellid of moderate size 

bearing fine parvi- to multicostellate ornamentation 

averaging 31j~ costellae in the space of 1 mm. Interarea slightly concave, 21j2 times wider than high, 

having wide perideltidium. 

Description.-Shell biconvex, in some specimens 

approaching resupinate in shape. Pedicle valve 

strongly convex posteriorly, less convex anteriorly; 

anterior and lateral slopes less convex and moderately inclined. Greatest width near middle of 

valve; lateral margins curving toward interarea 

postriorly. Shallow medial sulcus present in anterior 

part in some specimens (squeezed into deep irregular 

trough in lectotype by distortion after burial) . Interarea concave in side profile, its height equal to 

approximately two-fifths its width, inclination to 

plane of commissure varying from 100° (in lectotype) to 170° (in figured paralectotype). Pseudodeltidium occupying one quarter, or slightly more, 

of width of interarea, its sides (determined in several 

specimens) diverging forward at angles of from 20° 

to 25°; perideltidium wide, its outer edge approaching to within 11j~ to 2 mm of sides of interarea 

anteriorly. Umbo excentric, flattened posteriorly, 

and gently incurved. 

Pedicle valve sculptured by fine capillae, which 

increase by intercalation; normally 16 to 18 capillae 

occur in space of 5 mm ; intercostal grooves generally wider than capillae. Radial s·culpture crossed by 

finer concentric lirae. 

Interior of palintrope of pedicle valve bearing two 

nearly parallel dental plates that extend forward 

along floor of valve to about one-half its length; 
BRACHIOPODA OF THE AMSDEN FORMATION D25 

(k 

\\ ! ) A I I I 

\ I I 

\ I I 

\ I I 

',,,/ 

c 

E 

B D F 

G 

FIGURE 3.-Profiles of orthotetoid brachiopods in the Amsden Formation (all natural size). A, Sclwchertella poposiensis (C. 

Branson). B, Orthotetina amsdenensis (Branson and Greger). C, Puls·ia sp. A. D, P. deli1·a n. sp. E, 0Tthotetes s'p. A. 

F, 0. kaskaskiensis bransonorztm n. subsp. G, Derbyia cf. D. ro·busta (Hall). 

these are 0.8 mm apart posteriorly and 1.5 n1m apart 

at their anterior ends. 

Brachial valve convex, more strongly so than 

pedicle valve, greatest convexity near hinge line; 

outline subcircular. Surface sculpture approximately 

same as on pedicle valve. Details of cardinal process 

not exposed in primary types, but rather strong pair 

of chilidial plates present in one paralectotype (pl. 2, 

fig. 7). Cardinal process supported within brachial 

valve by pair of rather straight socket plates, diverging at angle of 55° and extending to points 11 mm 

from center of hinge line. Between these plates, subtriangular muscle field is rudely flabellate radially, 

bisected by shallow narrow median ridge. 

Dimensions (in mm) .-

Lectotype Paralectotype 

Length ---------------------------- 23 291h 

Maximum width -------------------- 231h 1 31% 

Thickness (both valves) ------------ 16 9.2 

Height of interarea ---------------- 5 7% 

Width of interarea ---------------- 12 19 1 Twice the half width. 

Branson and Greger's syntypes consist of three 

specimens in the collection of the University of 

Missouri Museum of Geology, catalog No. 2643. Of 

these, the specimen figured by Branson and Greger 

(1918, pl. 18, figs. 23, 24) is hereby designated the 

lectotype. This specimen is the one figured by Branson and Greger (1918, pl. 18, fig. 22) at a slightly 

greater diameter than actual. The other specimen 

figured by Branson and Greger (1918, pl. 18, fig. 25) 

and a less complete unfigured specimen in the same 

lot are paralectotypes. A previously unrecorded incomplete shell from 20 miles south of Lander is 

UM 10891. 

This distinctive species is the only nonplicate 

"M eekella" known in the United States. M eekella 

striaticostata (Cox) the long-ranging and widespread plicate species, has been reported from the 

Upper Mississippian Redoak Hollow Formation of 

Oklahoma by Elias (1957, p. 493, 494, pl. 52, fig. 5). 

M. striatocostata also occurs in limestone of late 

Chesterian age in the subsurface of the Black Warrior basin in northern Mississippi. 

The Amsden species closest to Orthotetina amsdenensi.s is the one described in this paper as Pulsia 

sp., which differs principally in having a less tumid 

shell with much shorter, more widely spaced dental 

plates in the pedicle valve and slightly coarser sculpture. 

Types.-Lectotype and paralectotypes, UM 2643. 

Occurrence and numbwr of specimens.-Horseshoe 

Shale Member, collections 27 (2), 36a (2), 36b (3), 

36c (1), Fremont County. 

Genus PULSIA Ivanov, 1925 

Pulsia Ivanov, 1925, p. 113. 

Schellwienella (Pulsia) Ivanov. Muir-Wood and Williams, in 

Moore, 1965, p. H407. 

Descript-ion.-Shell medium-sized to large, resembling Derbyia. Pedicle valve almost flat, having low 

broad interarea and rather narrow delthyrium. 

Brachial valve strongly convex. Both valves bearing 

surface sculpture of costellae and capillae increasing 

by intercalation. Within palitrope a pair of high thin 

dental plates connects margins of delthyrium with 

floor of valve, extending forward and dying out 

gradually along floor at either side of elongate oval 

cavity, anterior margin of which is marked by narrow shoulder slightly raised above floor of valve; 

this scooplike structure may reach lengths of 20 to 

25 mm in large specimens; dental plates meet and 

fuse at apex of delthyrium. Muscle scars located on 

floor of structure, marked by faint pinnate pattern; 
D26 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

muscle field intersected by three elongate ridges and 

in some speciments two additional faint ridges. Interior of brachial valve imperfectly known. Cardinal 

process fairly short, less than half the height of the 

delthyrium, four-lobed. 

Type species.-Pulsia mosquensis Ivanov, 1925. 

The description above is based on Ivanov's original 

description as translated from the Russian by Jose--

phine Cooper, but has been rearranged and slightly 

altered. Ivanov pointed out that the unity of the 

scooplike structure of which the dental plates are 

a part is accentuated by the fact that the floor of 

the valve between the plates is thickened and somewhat elevated above the rest of the surface and also 

is covered by a porcellaneous substance identical in 

appearance to that composing the plates. 

Muir-Wood and Williams (in Moore, 1965, p. 

H407) regarded Pulsia as a subgenus of Schellwienella, but there is reason to regard them as separate genera. Pulsia possesses true dental plates, resembling those in M eekella, but shorter. The socalled dental plates in Schellwienella, which diverge 

much more widely and border a prominent, rather 

deeply impressed muscle-scar field seem to be composed only of secondary shell material. G. A. Cooper 

(oral commun., 1968) has suggested that for this 

reason Schellwienella may be closely related to 

Schuchertella, perhaps even congeneric. 

The genus Pulsia is recognized here for the first 

time in North America, by two species, both of them 

older than those described by Ivanov from the Moscow Basin. Pulsia deli1·a n. sp. is from beds of Pennsylvanian (Morrowan or Atokan) age. Pulsia sp. A 

occurs in rocks of late Chesterian age. The presence 

in U.S. Geological Survey collections from the 

Boone Formation of Oklahoma, Missouri, and Arkansas of an undescribed species showing incipient 

structures within the pailintrope that resemble those 

of Pulsia suggest that this genus may actually have 

had its origins in the American midcontinent. 

Pulsia delira n. sp. 

Plarte 2, figures 22-26, 32; text figure 3D. 

Diagnosis.-Pulsia with convexo-concave shell 

having relatively low interarea inclined at angles 

of 85° to 95° to plane of commissure. Ornamentation 

multicostellate, about three capillae occurring in 

space 1 mm. 

Descript·ion.-Shell shallowly convexo-concave. 

PPdicle valve concave posteriorly, nearly fiat anteriorly, gently convex in areas of cardinal extremities, subcircular to transversely suboval in plan, 

with well-rounded lateral margins; greatest width 

approximately at middle of valve. Posterior margins 

of valve form abtuse angle with lateral margins at 

cardinal extremities. Apex low; apical angle roughly 

160°; interarea broad, nearly fiat, its height slightly 

more than one-fifth its width, tilted in holotype at 

angles of 100° to plane of commissure and 75° to 

plane of pedicle valve; same angles in para type, 95o 

and 65°, respectively. Triangular delthyrium closed 

by pseudodeltidium, its apical angle 27° in holotype. 

Pedicle valve sculptured by fine closely spaced 

costellae, with slightly narrower intercostal sulci, 

increasing by intercalation, appearing multicostellate 

on fragment of external mold. Normally 13 to 15 

capillae occur in space of 5 mm. Concentric sculpture limited to very sparsely distributed growth 

furrows and swellings. 

Interior of pedicle valve has pair of slightly diverging dental plates extending from sides of delthyrium to floor of valve, where they are 8 to 9 mm long, 

spaced about 2 mm apart near apex of valve and 3¥2 

to 4 mm apart at their anterior ends; plates cut 

smooth subc.ircular area on floor of valve, about 

10 mm in diameter; anterior edges of dental plates 

concave. 

Brachial valve deeply convex, suboval, much 

wider than long, strongly inflated in posterior part, 

with greatest curvature near cardinal process and 

decreasing gradually toward anterior margin; lateral slopes fairly steeply inclined .. Surface· sculpture 

of valve as on pedicle valve; along anterior margin 

in figured specimen (USNM 163724) 20 to 21 

capillae ocur in space of 5 mm. 

Interior of brachial valve posteriorly with pair of 

broadly diverging socket plates, about 9 mm long, 

bounding adductor muscle field, which is bisected 

by weak narrow ridge; socket plates spaced about 

5 mm apart at base of cardinal process and 10 mm 

apart at their anterior ends. Cardinal process fairly 

broad, gently curved; details not preserved in this 

material. 

Dimension (in mm) .-

L·ength of valve __________ _ 

Length along curvature ___ _ 

Maximum width __________ _ 

Width of interarea --------

Height of interarea --------

Depth of valve ------------

1 Holotype. 

!l Twice the half width. 

USNM 

163722 

36 

37 

2 44 

2 35 

7% 

7 

Pedicle Brachial 

valves ·oalve 

USNM 

1168721 

33 

34 

47 

33 

7 

6% 

USNM 

163724 

26 

41 

36 

21 

Discussion.-The description above is based 

mainly on two nearly complete internal molds of the 

pedicle valve from a chert bed near the top of the 

Amsden Formation and one of a brachial valve from 
BRACHIOPODA OF THE AMSDEN FORMATION D27 

the same bed at approximately the same locality. 

Because they were not found in articulation nor even 

in the same collection, the possibility exists that the 

brachial and pedicle valves do not belong to the same 

species, but the typically schellwienellid arrangement 

of the socket plates in the brachial valve and the 

similarity of the sculpture pattern in both valves 

make that possibility highly unlikely. A reconstruction of the two valves in articulation is shown in 

figure 3D. The holotype bears a few poorly defined 

radial swellings which are absent on the paratype 

and therefore considered pathologic. 

Pulsia delira is distinguished by its striking convexo-concave shape from all the other davidsoniacean strophomenoid brachiopods in the Amsden 

Formation, with the possible exception of Derbyia 

cf. D. robusta Hall. The Derrbyia can be distinguished, however, by its less inflated brachial valve 

and by the presence of a media septum in the pedicle 

valve. 

The pair of slightly diverging dental plates that 

reach the floor of the pedicle valve and the rather 

evenly fine radial shell sculpture ally Pulsia delira 

with Orthotetina atnsdenensis (Branson and Greger). 0. amsdenensis has, however, a narrow irregularly biconvex shell with a high steeply inclined and 

shallowly concave interarea and a long closely 

spaced parallel pair of dental plates, by which it 

can easily be distinguished from P. delira. 

Stratigt·aphic considerations.-The stratigraphic 

posi·cion of P. delira near the top of the Amsden 

Formation in eastern Wyoming as well as its associated faunule show that this species is part of the 

Pennsylvanian fauna. 

Types.-Holotype, USNM 163721; paratypes, 

USNM 163722-163724. 

Occurrence and number of specimens.-Ranchester Limestone Member: collection 5-2 (4), Johnson 

County. 

Pulsia sp. A 

Plate 2, figures 4-6; text figure 3C 

Three incomplete specimens from the Moffat Trail 

and Covey Cutoff sections are referred to Pulsia 

and represent a different and earlier species than 

the one from the Ranchester in north-central Wyoming. As the anterior parts of all three specimens 

are missing it is not possible to tell whether the 

shells are biconvex or resupinate. One of them, retaining parts of both valves, is figured (pl. 2, figs. 

4-6). 

The ventral valve is gently convex, at least in the 

posterior part, and appears roughly subcircular to 

transversely oval, the greatest width probably occurring near the middle of the valve. The interarea 

is steep, gently concave in longitudinal profile, and 

lies nearly in the plane of commissure. It is relatively narrow and moderately high, with an apical 

angle of roughly 120° ; the delthyrium is narrow with 

apical angles in two specimens of 12° and 17°, covered by a raised pseudodeltidium. The perideltidium, 

seen faintly in an unfigured specimen, extends from 

the apex of the interarea to points about halfway 

from the edge of the pseudodeltidium to the end of 

the interarea at either side. 

Dental plates, diverging slightly and discernible 

in all three specimens, extend from the apex along 

the sides of the delthyrium and connect with the 

floor of the valve. In the figured specimen they are 

4lf2 mm long and 3 mm apart at their anterior ends; 

in the unfigured ones, 5.2 and 6.5 mm long and 3 

and 31;2 mm apart, respectively. 

The brachial valve is convex, rather gently so near 

the umbo, the greatest convexity occurring, so far 

as can be determined, posterior to the middle of the 

valve, which slopes off in all directions to the margins. Internal structures of the brachial valve were 

not seen. 

Surface sculpture in both valves is multicostellate, 

resembling that of Pulsia delira n. sp., 13 to 16 

capillae occurring in a space of 5 mm on the more 

anterior parts of the valves. 

The figured specimen is 211;2 mm long (with perhaps two-fifths of the length missing), 30 mm wide, 

and 10lf2 mm thick (both valves). The interarea in 

the pedicle valve is 22 mm wide and 41;2 mm high. 

On one of the unfigured specimens, the interarea is 

19 mm (twice the half width) and 5 mm high. 

This species is distinguished from Pulsia delira 

n. sp. by its more convex pedicle valve, having a 

narrower, more steeply tilted interarea and shorter 

dental plates, and the less inflated brachial valve. 

From Orthotetina amsdenensis it is distinguished 

by its less tumid shell with a wider lower interarea 

in the pedicle valve and shorter diverging dental 

plates. 

The stratigraphic position of this species, together with its associated fossils, demonstrate that 

the beds that contain it are Chesterian in age. 

F1:gured specimen.-VSNM 163719. 

Mentioned specimen.-VSNM 163720. 

OccutTence and number of specimens.-Moffat 

Trail Limestone Member: collection 72 (2), Lincoln 

County. Ranchester Limestone Member: collection 

95 (1), Lincoln County. 
D28 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Family SCHUCHERTELLIDAE Williams 

Genus SCHUCHERTELLA Girty, 1904 

Schuchertella poposiensis (C. Branson) 

Plate 1, figures 51, 53; plate 2, figures 8-10, 12-17; text 

figure 3A .. 

Streptorhynchus poposiensis C. Branson, 1937, p. 655, pl. 89, 

figs. 10-12. 

Diagnosis.-SmaH biconvex SchucheTtella, subcircular in outline; interarea three times wider than 

high; parvicostellate sculpture. Brachial valve shallowly to moderately convex. 

Description.-Pedicle valve gently convex, slightly 

wider than long; greatest width just anterior to 

middle 0f valve; lateral margins curving inward 

posteriorly to meet shorter hinge line ; posterior 

margins fairly straight; apical angle ranging from 

120° to 130°. Interarea fiat, inclined at angle ranging 

from 130° to 140° to plane of commissure; height 

of interarea approximately one-third its width; delthyrium covered by pseudodeltidium occupying about 

one-fifth of interarea, its sides diverging anteriorly 

at 30° angle; perideltidium moderately narrow. 

Surface of pedicle valve covered by narrowly 

rounded to subacute costellae separated by subequal 

to narrower intercostal sulci. Fine intercalating 

threads at intervals between coarser costellae give 

parvicostellate appearance to ornamentation; 10 to 

14 costellae occur in space of 5 mm on anterior and 

lateral slopes of valve. Radial sculpture crossed by 

very fine concentric growth lirae. Interior of pedicle 

valve with delthyrium bordered by dental ridges. 

Brachial valve moderately convex, fiat near umbo, 

greatest curvature just posterior to middle, gently 

convex on anterior and lateral slopes; anterior third 

with shallow median sulcus. Surface sculpture approximately as on pedicle valve. Interior of brachial 

valve not known. 

Dimens1~ons (in mm) .-

Length --------------------------

Maximum width ------------------

Thickness (both valves) _________ _ 

Height of interarea _____________ _ 

Width of interarea ______________ _ 

1 S:lightly crushed. 

USNM USNM 163725 1GJ726 

17.5 

18.5 

8 

4.3 

13 

15.2 

16.3 

l 6.5 

4.4 

13 

Discuss,ion.-The diagnosis and description given 

above are based upon two specimens in the U.S. 

National Museum collected by I. A. Keyte from the 

Amsden Formation at an unknown locality near 

Lander, Wyo. Branson's type specimens came from 

the Little Popo Agie River, roughly 15 miles south 

of Lander, and were tiny immature examples found 

with ostracodes collected by P. S. Morey in 1932. The 

largest of these is a paratype (UM 6833) 3.8 mm 

long; the holotype is 1.0 mm wide. The writer is 

convinced that Keyte's specimens represent the 

adult stage of Branson's species, despite some minor 

disagreement between Branson's description and his. 

Branson's statement, for example, that the pedicle valve is "twice as wide as long" does not fit any 

of the specimens. Branson's figures, as well as his 

type specimens, show that the length of the shell 

in this immature stage ranges from two-thirds to 

four-fifths the width. These proportions are approximated in the apical part of Keyte's specimens. 

The interarea shown in one of the immature specimens figured by Branson (1937, pl. 89, fig. 12) has 

a height equivalent to 36 percent of the width of 

the interarea, compared with 33 percent in both of 

Keyte's adult specimens. Direct comparison of 

Branson's types with Keyte's specimens also shows 

that the sculpture pattern is the same. 

Branson described this species as a Streptorhynchus and the shape of the Fremont County specimens approaches that genus. The writer, however, 

has identified as Schuchertella cf. S. poposiensis, 

specimens from Carbon County, Mont., a little north 

of the State line, on the west flank of the Bighorn 

Mountains. These are incomplete silicified valves 

that on etching show typical internal characters of 

Schuchertella. The pediele valve of this form, its 

internal structures limited to dental ridges at either 

side of the delthyrium, appears almost identical 

externally with that of the material from near 

Lander, but the brachial valve is flatter. The cardinal process and its supporting socket plates are 

typical of the genus Schuchertella. The socket plates 

are short and diverge laterally, where they are recurved toward the posterior margin (pl. 1, fig. 51). 

Schuchwrtella poposiens1~s is the smallest of the 

Amsden davidsoniacean strophomenoids and can 

also be distinguished by its rather narrowly biconvex shell and subcircular outline with its obtusely 

angular apex. The only two shells likely to be confused superficially with it are Orthotetina amsdenens1:s (Branson and Greger) and Pulsia sp. A. The 

Orthotetina is normally a more tumid species, less 

regularin shape, having a higher concave interarea 

with a much wider perideltidium. The P'ltlsia is also 

somewhat irregular and has a narrow, somewhat 

concave interarea. Both species are equipped with 

a pair of dental plates, lacking in S. poposiensis. 

Types.-Holotype, UM 6598; paratypes (labeled 

"cotype," "meta types," and paratype), UM 6596, 

6614, 6615, 6833 (5 specimens); hypotypes, USNM 

163725, 163726. 
BRACHIOPODA OF THE AMSDEN FORMATION D29 

Figured specimens.-(Schuchertella cf. S. poposiensis) USNM 163709, 163727, 163739, 163740. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 36d, (6), E (2), Fremont 

County; collection 69 ( cf) (3), Carbon County. 

Family ORTHOTETIDAE Waagen 

Genus ORTHOTETES Fischer de Waldhei'm, 1829 

Orthotetes kaskaskiensis bransonorum n. subsp. 

Plate 1, figure 54; plate 2, :figures 27-29; text figure 3F. 

Orthotetes kaskaskiensis (McChesney). Branson and Gre,ger, 

19'18, p. 314, pl. 19, figs. 3, 4. 

?Orthotetes? sp. Burk, 1954, p. 9, P'l. 1, fig. 1. 

Orthotetes (Orthotetes) sp. Easton [p·art], 1962, p. 42, 43, pl. 

5, figs. 1-4 [not fig. 5]. 

Diagnosis.-Like Orthotetes kaskaskiensis (McChesney) but differing from typical form in having 

markedly parvicostellate ornamentation, averaging 

two costellae in space of 1 mm, and lesser convexity 

of brachial valve·. 

Description.-Shell resupinate to shallowly convexo-concave; umbonal region gently convex. Pedicle 

valve transversely suboval in outline; greatest width 

near midlength. Posterior margins nearly straight 

to slightly concave; apical angle ranging from 115° 

to 145°. Interarea rather wide, in some shells approaching but not equaling greatest width, low, generally sloping about 125° to plane of commissure, but 

reaching 90° (in holotype) ; perideltidium occupies 

roughly half of width of interarea; delthyrium, 

about one-eighth of width of interarea, its sides 

diverging toward anterior edge at angle of about 

35o. Surface of valve covered with radiating costellae 

of different ranks added solely by intercalation in 

parvicostellate arrangement; 17 to 22 costellae occur in space of 10.0 mm in anterior parts of shell. 

Inte·rcostal sulci wider than costellae. Radial sculpture crossed by fine concentric lirae. 

Interior of pedicle valve with prominent median 

septum in posterior third of shell; septum unites 

with pair of stout dental plates that extend forward and toward it from margins of delthyrium, 

forming small subtriangular spondylium within 

umbo. 

Brachial valve gently convex, except for pair of 

subtriangular gently concave areas near hinge, one 

at either side of umbonal region; greatest convexity 

near middle of valve; sloping toward margins. Surface ornamentation like that of pedicle valve. Cardinal process bifid, each lobe with a deep longitudinal 

groove, lobes uniting anteriorly; process set off by 

pair of chilidial plates. 

Two specimens (holotype and paratype) collected 

by Branson and Greger measure (in mm); length 

31 and 32, width 43 and 38, thickness 8 and 10, 

respectively. 

Discussion.-This new subspecies is erected to 

contain Late Mississippian (Chesterian) specimens 

of Orthotetes from the Rocky Mountain region that 

differ from the typical form in having a decidedly 

parvicostellate arrangement of the costellae. Spedmens from the American midcontinent from rocks 

of both Meramecian and Chesterian age have a 

surface sculpture that is considerably more multicostellate in aspect. The costellae of these shells are 

inserted by intercalation; they tend to increase in 

size rapidly and attain the approximate strength of 

earlier costellae. Near the shell margins it is virtually impossible to distinguish between different 

ranks of intercalary costellae by strength alone. 

Comparing shells from the two regions, those from 

the Rocky Mountain region appear to be more 

coarsely or sparsely costellate, but this is largely an 

illusion produced by the parvicostellate arrangement 

of surface sculpture on the western form. If one 

counts the very fine intercalaries as well as the 

coarser costellae on the western shells, the number 

per unit measurement is seen to be approximately 

the same as on the typical form, on which all of the 

costellae tend to be strong and the interspaces narrow. The more convex brachial valves of the typical 

0. kaskaskiensis have their greatest convexity about 

one-quarter to one-third of the way forward from 

the posterior margin of the valve. 

The type specimens of this subspecies are from 

Cherry Creek in the Wind River Range. The bolotype is the specimen (UM 2662a) figured by Branson and Greger (1918, pl. 18, fig. 4) as 0. kaskaskiensis (McChesney), and one of the paratypes is 

the shell (UM 2662b) from which they figured the 

interarea (Branson and Greger, 1918, pl. p. 18, fig. 

3). Two additional incomplete shells in the U.S. Geological Survey ·collection, presented by Carl Branson, 

are also designated as paratypes and illustrated on 

plate 1, figure 54 and plate 2, figure 29. 

This subspecies is very common at Berry Creek 

in the Teton Range where its shells form a mat in 

some shale beds. Unfortunately, these layers which 

locally are almost coquinoid have not yielded wellpreserved and complete specimens. Beaks of pedicle 

valves that have been ground down expose the spondylium partly filled with secondary shell material. 

A pedicle valve from Horse Creek in the Wind 

River Mountains, apparently distorted or aberrant 

because it is convex throughout, was described and 

figured by Burk (1954, p. 9, pl. 1, fig. 1) as 

Orrthotetes? sp. Someone has ground down the sur-
D30 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

face slightly in the area of the beak, disclosing a 

rather strong median septum, which appears to be 

inserted at the umbo between two short darker 

colored plates. The grinding did not progress far 

enough to determine if a spondyli urn is present. 

As the details of the interarea resemble those of 0. 

kaskaskiensis b1·ansm·orum and remains of the 

sculpture show that the surface has ornamentation 

closely resembling that of this species, Burk's specimen is placed, but still with some question, in the 

synonymy of this subspecies. 

Shells from the Otter and Heath Formations in 

central Montana, described and figured by Easton 

(1962) as Orthotetes (Orthotetes) sp., also are referred to this subspecies. 

Types.-Holotype, US 2642a; para types, UM 

2642b, USNM 163728, 163729. 

Occu1Tence and 17/Umbwr of spec·imens.-Moffat 

Trail Limestone Member: collection 120 ( 5) , Teton 

County. Horseshoe Shale Member: collections 27 (2 

fragments), ?31 (1), 36a (2 fragments), 43 (1), 

?45 (2), ?47 (2), Fremont County; ?149 (15), ?151 

(fragments), 152 (6), 153 (10), ?155 (3), 156 (1), 

157 (4), ?158 (1), Teton County. 

Orthotetes sp. A 

Plate 2, figure:s 19-21; text figure 3E 

Ortkotetes (Orthotetes) sp. Easton [part], 196·2, p. 42, 43, 

pl. 5, fig. 5 [not. figs. 1-4]. 

Ortkotetes (Derbyia) sp. Easton [part?], 1962, p. 43 [?not 

pl. 4, figs. 17, 30]. 

Desc1·iption.-Shell shallowly convexo-concave, 

subcircular in plan. Pedicle valve concave except for 

small gently convex umbonal region. Posterior margins straight, except near umbo which in some specimens is slightly elevated and excentric; apical angle 

ranging from 100° to 170°. Hinge line shorter than 

greatest width, which occurs near midlength; lateral 

margins rounding posteriorly into interarea. Interarea moderately low, 4 mm high and 15 mm wide 

and inclines at angle of 125° to plane of commissure 

in figured specimen (pl. 2, fig. 21). Pseudodeltidi urn 

moderately narrow, occupying slightly less than oneseventh of interarea width, its sides diverging anterior margin at points midway between center and 

lateral extremities of interarea. 

Sculpture of pedicle valve parvicostellate but approaching multicostellate in central part; costellae 

separated by subequal intercostal sulci centrally, 

and slightly wider ones toward auricular extremities; 18 to 26 costellae occur in space of 10 mm. 

Fine concentric growth lirae cross costellae. 

Interior of pedicle valve having moderately short 

median septum terminating apically in tiny spondyliform structure. Sectioning shows structure 

formed by dental plates buried within callus at apex 

and anteriorly delimiting tiny open pocket a little 

more than 1 mm in diameter; dental plates evanesce 

rapidly and become dental ridges anteriorly, within 

2 to 3 mm of apex. 

Brachial valve moderately convex; greatest convexity posterior to middle of valve and decreasing 

anteriorly; anterior and lateral slopes moderately 

inclined and gently convex; some specimens have 

shallow median sulcus in posterior part lessening 

to mere medial flattening of valve anteriorly. Surface s·culpture of brachial valve similar to that of 

pedicle valve. 

Internal structures of brachial valve poorly 

known. Cardinal process about 21j2 mm wide, arched, 

supported by short socket plates that extend slightly 

less than 5 mm anterolaterally from umbo of valve. 

Adductor muscle field divided by shallowly discontinuous median ridge. 

Pedicle valves not complete enough to give dimensions. Figured brachial valve is 28 mm long, 34 mm 

wide and 8 mm deep. 

Discussion.-This species differs from Orthotetes 

kaskiensis b1·ansonorum n. subsp. in having multicostellate sculpture, a narrower pseudodeltidium, 

and a shorter, less developed spondylium in the 

pedicle valve. Direct comparison with material collected by the writer and by Easton (1962, p. 42, 43) 

from the Alaska Bench Limestone in the Big Snowy 

Range, Mont., and cited by Easton as Orthotetes 

(Derby·ia) sp. indicates that this is the same as the 

Montana species. Easton (1962, piJ.. 5, fig. 5) also 

figured one of the Alaska Bench specimens as 

01·thotetes ( 01·thotetes) sp. 

Orthotetids with a tiny spondylium within the 

apical region of the pedicle valve here in the past 

been referred by paleontologists either to Ortlwtetes or to Derbyia. Presumably this vestigial structure represents a transitional stage between the two 

genera. Having been among those who once argued 

for Easton's identification of this species as a 

Derbyia, I hope that the brief discussion in this 

report under the genus 01·thotetes will explain to 

the reader why I now consider it more correctly referred to Orthotetes. Briefly, the short socket plates 

in the brachial valve, together with the tiny· spondylium in the pedicle valve, place this species in 

Orthotetes. 

A pedicle valve figured by Easton (1962, pl. 4, 

figs. 17, 30) from the Devils Pocket Formation appears to have no spondylium; that is, no dental 

plates or ridges are in contact with the median sep-
BRA,CHIOPODA OF THE AMSDEN FOR.MATION D31 

tum. Brachial valves from the same collection still 

retain relatively short socket plates. It is questionable whether these shells from the Devils Pocket 

Formation should be included with this species. 

Figu,rred specimens.-VSNM 163731-163733. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 53 (19), 54 (4), Johnson 

County. Ranchester Limestone Member: collections 

?84 (10), Lincoln County; 139 (2), 141 (6), Teton 

County. 

Ortbotetes sp. 

Pl&te 2, figures 11, 18 

An incomplete septate pedicle valve from the 

Moffat Trial Limestone Member is referred to 

Orthotetes. Concentric growth furrows and ridges 

indicate that the length of the valve is equal to 

about three-quarters its width, the lateral margins 

slightly recurved to meet the posterior margins at 

an angle of about 100°. Except for the elevated area 

around the umbo, the valve is flat, with irregularities. The interarea also is flat, inclined at an angle 

of 73° to the plane of the valve, 9 mm high, its 

length not known but estimated to be 45 to 50 mm. 

The delthyrium, partly covered by a pseudodeltidium, most of which has been broken away anteriorly, has an apical angle of approximately 30° and 

is 5 mm wide at the hinge line. A prominent, slightly 

elevated perideltidium is 23 mm wide (twice the 

half length) at the hinge lne. The umbo is acute 

and slightly incurved. 

The surface sculpture is parvicostellate, consisting of narrow, rather sharp costellae separated 

by much wider interspaces; eight to nine costellae 

occur in the spa~e of 5 mm. These are crossed by 

fine concentric lirae, strongest and somewhat zigzag in the intercostal sulci. A medium septum is 

present. 

This shell appears to be nearest to Ot'thotetes kaskaskiensis bt·ansonorum n. subsp. but differs in 

having a higher interfarea, narrower delthyrium, 

more prominent perideltidium, and slightly wider, 

spaced costellae. Whether dental plates are developed or not is not known, but because the stratigraphic position of this shell is well below the lowest 

known occurrence of DeYbyia in the west American 

section, it has been referred to Orthotetes. 

Figured specitnen.-VSNM 163730. 

Occurrence and nu1nber of specimens.-Moffat 

Trail Limestone Member: collection 93 (1), Lincoln County. 

Genus DERBYIA Waagen, 1884 

Derbyia cf. D. robusta (Hall) 

Plate 2, figures 30, 31, 33-35, text figure 3G 

Or·this robu.sta Hall, 1858, p. 713, 714, pl. 28, figs. 5a-d. 

Derbya robusta Hall. Hall and Clarke [part?], 1892, pt 10, 

figs.12-15 [not figs.16, 17]. 

Description.-Pedicle valve shallowly convex to 

approximately flat, with convex umbonal region; 

outline transversely subelliptical; greatest width 

near middle of valve; hinge line somewhat shorter 

than greatest width; shell rather irregularly thickened concentrically near anterior and lateral mar~ 

gins, commonly with rather prominent concentric 

furrow a few millimeters from edge. Interarea 

moderately low, wide, and slightly concave in side 

profile, inclined at angle of 120° to plane of commissure. Umbo slightly protruding, shallowly incurved, and bluntly pointed. Pseudodeltidium narrow. 

Strong external sculpture in pedicle valve consists 

of narrow elevated costellae separated by wider 

intercostal sulci; 8 to 10 (normally 9) costellae occur 

in space of 5 mm. Sculpture parvicostellate, having 

weaker costellae intercalated between two stronger 

ones. Radial sculpture crossed by low concentric 

threads giving minutely beaded appearance to points 

of junction with costellae. Shallow growth furrows 

and minute growth lirae also present. Pseudopunctae 

exposed on partly eroded shells. 

Interior of pedicle valve marked in umbonal re~ 

gion by median septum on floor of valve that bisects 

somewhat flabellate muscle-scar field. Field rests on 

rudely subtriangular callus, about 20 mm long and 

18 mm wide in one specimen (USNM 163738), bordered by slightly raised ridge. Dental thickenings or 

ridges flank delthyrium. 

Brachial valve broad, tumid, strongly convex 

throughout, in side and anterior profiles; greatest 

convexity near umbo. Anterior part generally less 

thickened than in pedicle valve, but faint concentric 

furrows present in some specimens. Surface sculpture similar to that of pedicle valve, except that as 

many as five fine costallae intervene between two 

strong ones, with one or three costella more typical. 

Interior of brachial valve with bilobate cardinal 

process extending outward at posterior margin, approximately at right angles to plane of commissure; 

chilidial plate strong, divided; cardinal process 

strongly arched anteriorly, extending anterolaterally in pair of socket plates of undetermined length; 

no anterior median ridge visible on underside of 

process. 
D32 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Dimensions (in mm) .-

Length ------------------ Maximum width ________ _ 

Thickness --------------- Height of interarea _____ _ 

Width of interarea ______ _ 

1 Estimated (broken umbo). 2 Twice the half width. 

USNM 

163734 

1 45 

54 

10 

8 

48 

Pedicle 

1•alves 

USNM 

163737 

46.5 

2 56 

9 

7 2 48 

Brachial 

·valve 

USNM. 

1637&5 

35 

48 

18 

Dimensions of Hall's holotype of D. robusta 1 (in 

1nm).-

Length -----------------------

Maximum width ------------------

Thickness ------------------------

Height of int,erarea --------------

Width of interarea --------------- 1 From the plastoholotype, USNM 62502. 

Pedicle Bruchinl valve valve 

64.5 

76.5 

13 

11 

68 

58.5 

76.5 

22 

Discussion.-The description above is based upon 

specimens from the Ranchester Limestone Member 

in the Rawlins hills, where this species seems to be 

fairly common. The Amsden specimens are closely 

related to Derbyia robusta (HalO, described originally from beds of probable Des Moinesian age 

(Dunbar and Condra, 1932, p. 113) in St. Clair 

County, Ill., and probably are conspecific with that 

species. They are somewhat smaller than Hall's 

holotype which, according to Dunbar and Condra 

(1932, p. 113), is lost. Plaster -casts of it, however, 

are in the collections of the U.S. National Museum 

and the American Museum of Nat ural History. One 

of these (USNM 62502) has been compared directly 

with the Wyoming material; its measurements are 

given in the table above. 

One moderate discrepancy between the Wyoming 

species and Hall's original description is the presence of a shallowly convex pedicle valve in Wyoming 

shells and of a flat pedicle valve, concave, in the 

middle, in Hall's type. On close examination the 

cast of the holotype shows a strongly convex urnbona} region; including the interarea, the convexity 

amounts to 13 mm. Near the anterior margin of the 

valve the convexity amounts to 7 mm. In between, 

the central part of the valve is shallowly concave. 

Possibly this central depression in the valve was 

caused by crowding during growth or by slight 

compaction after burial. 

Characteristic of Hall's species and of the Wyoming specimens are the following: the considerable convexity of the brachial valve, the wide interarea inclined at 120° to the plane of commissure, 

and the fairly coarse sculpture-eight to nine costellae in the space of 5 mm on the plastoholtype. 

One unresolved difference remains. The only interarea exposed in a \Vyoming specimen is gently 

concave in side profile, whereas that of Hall's specimen is approximately flat. This difference, the lack 

of sufficient topotype material of D. robusta to work 

out of its range of variation, and the lack of sufficient Wyoming specimens with palintropes suitable 

for grinding and sectioning are responsible for the 

Wyoming shells being merely compared with Hall's 

species. 

In the Amsden Formation the presence of a median 

septum in the pedicle valve will distinguish this 

species from all davidsonaceans except those referred 

to Orthotetes, and the highly convex brachial valve 

will distinguish it from these, as well as the others. 

Derbyia robusta has been cited in the literature at 

several localities, but most of these occurrences 

should be reviewed. The Orthotetes robusta (Hall) 

figured by Mather (1915, p. 146, pl. 9, figs. 2-3a) 

from the Morrowan Series of Arkansas, as well as 

the Derbya robusta figured by Morningstar (1922, 

p. 177, pl. 8, fig. 11) from beds of Pottsville age in 

Ohio almost certainly do not belong in this species. 

Figured specimens.-VSNM 163734-163737. 

Mentioned specimen.-VSNM 163738. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 1 (3), 2 (1), 3 (6), 4 

( 4), ?5 ( 1), Carbon County. Ranchester Limestone 

Member: collections 6 (1), ?15 (3), Carbon County. 

Suborder CHONETIDINA 

Superfamily CHONETACEA Bronn 

Family CHONETIDAE Bronn 

Genus EOLISSOCHONETES Hoare, 1960 

Eolissochonetes Hom·e, 1960, p. 220; 1961, p. 37, 38; MuirWood, 1962, p. 75, 76; Muir-Wood, in Moore, 1965, p. 

H430. 

Desc·ription.-Smooth subrectangular chonetid~ 

with or without broad low sulcus in pedicle valve. 

Cardinal extremities approximately right-angled, 

ranging from slightly rounded to slightly produced. 

Interior of pedicle valve having median septum 

paralleled anteriorly by two main vascular trunks 

near middle of valve and ornamented by closely 

scattered papillae. Brachial valve having pair of 

socket ridges meeting just behind alveolus to support 

sessile cardinal process ; median septum moderately 

long and fairly high, extending forward from alveolus and apex of lateral septa, flanked by radial rows 

of papillae that in thick shells may be fused into 

radial ridges. 

Type spec1:es.-Chonetes laevis Keyes, 1888 [not 

Davidson, 1866] by original designation, ( = Eolissochonetes lceyesi Muir-Wood, 1962). 
BRACHIOPODA OF THE AMScDEN FORMATION D33 

Discussion.-Hoare (1960, 1961) stated his belief 

that Eolissochonetes was derived from M esolobus 

mesolobus decipiens (Girty), a smooth Mesolobus 

having a very subdued median lobe in the sulcus 

and regarded by Sturgeon and Hoare (1968, p. 30) 

as the typical form of M. mesolobus (Norwood and 

Pratten). He based this suggestion on the supposed 

closer similarity of the interior of Eolissochonetes to 

that of M esolobus than to that of Chonetes. This 

statement is difficult to evaluate at present because 

Hoare did not say which species of Chonetes he 

regarded as typical of the genus. The statement is 

certainly true of Chonetes as presently restricted to 

beds of Early Devonian to earliest Early Carboniferous age (Muir-Wood, 1962, p. 36; Muir-Wood, in 

Moore, 1965, p. H420). The Carboniferous species in 

North America formerly included in Chonetes are 

now referred variously to Rugosochonetes, N eochonetes, Retichonetes and other genera. One presumes that Hoare probably was referring to the 

common Pennsylvanian species Chonetes granuUferr 

Owen and related species now placed in N eochonetes. 

The internal differences between the type species of 

Eolissochonetes and typical Rugosoclwnetes and 

N eochonetes do not seem to me to be greater than 

those between E. keyesi and typical M esolobus. 

It is difficult, moreover, to conceive of evolution 

rapid enough to account for the derivation of E. 

keyesi from M. mesolobus decipiens when the two 

species occur together in the same beds of Middle 

Pennsylvanian (Des Moinesian) age in southwest 

Missouri. One wiJl have to go a little farther back, 

it would seem, to find the ancestors of E. keyesi. 

This species has, in fact, been identified by Mather 

(1915, p. 151) as "Chonetes laevis Keyes" from the 

type Morrowan of northwestern Arkansas, although 

whether it is the same as the shell from Des Moinesian Series is open to question. Also described by 

Mather (1915, p. 150) from beds he regarded as 

belonging in the Morrowan, but which M. K. Elias 

(oral commun., 1967) has determined as belonging 

in the overlying Atokan Series, was Chonetes choteauensis Mather, which probably was ancestral to 

Mesolobus. 

Chonetids with smooth shells, having interiors 

that are similar both to Eolissochonetes and Rugosachonetes are rather common in late Chesterian and 

Morrowan equivalents in the western United States. 

They probably were derived from Rugosochonetes 

through some species such as Chonetes sericius 

Girty, of the Fayetteville Shale of Arkansas and 

Oklahoma, which bears fine capillae in the medial 

part of the shell and has the auricular extremities 

virtually smooth. It is proposed here to refer the 

smooth Amsden chonetids to Eolissochonetes and 

to regard this genus as derived probably in Late 

Mississippian (Chesterian) time from species now 

included in Rugosochonetes. 

Eolissochonetes pseudoliratus (Easton) 

Plate 1, figures 42-50, 52 

Chonetes pseudoliratus Eas1ton, 1962, p. 44, 45, pl. 5, figs. 8-

13. 

Diagnosis.-Moderately small shell, gently concavo-convex; surface smooth, appearing lirate (capillate) where abraded. Interior of brachial valve 

having median septum fused posteriorly to pair of 

lateral septa. 

DescTiption.-Pedicle valve transverse suboval 

to semicircular in outline; posterior margins 

straight, diverging at apical angle of about 170°; 

greatest width approximately at midlength or, less 

commonly, at or near hinge. Surface evenly convex 

in side profile or having anterior part more convex 

than posterior part; anterior slope fairly flat or depressed into faint sulcus. Interarea low, inclined at 

angle ranging from 120°-140° to plane of commissure. Triangular delthyrium partly covered apically 

by gently convex pseudodeltidium. Surface smooth, 

sculptured only by sparse concentric grooves and 

lines of growth, but appearing capillate where 

abraded; 28 to 30 internal capillae oc·curring in 

space of 5 mm. Posterior margin ornamented by 

six or seven, rarely eight, spines of unknown length 

at either side of apex, diverging toward auricular 

extremities at angles approximating 60° to margin. 

Interior of pedicle valve having short platelike 

septum, highest near beak, extending forward as 

faint low ridge, terminating a little beyond midlength. Pair of adductor muscle scars occupying 

smooth sloping thickened areas at either side of 

midseptum. Pair of low short ridges, or vascular 

trunks, flanking end of septum and extending a little 

beyond it at middle of valve. Diductor muscle scars 

occupying slightly depressed fan-shaped areas, one 

at either side of median septum and vascular trunks, 

beginning just in front of apex and extending not 

quite to midlength, faint to unrecognizable on young 

shells. Radial rows of papillae well developed within 

valve, particularly in band near anterior and lateral 

margins. 

Brachial valve gently concave-either evenly so 

or almost flat posteriorly and moderately concave 

anteriorly. Surface sculpture like that of pedicle 

valve. Interarea inclined at angles ranging from 

55°-75° to plane of commissure. Notothyrium closed 
D34 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

apically by crescent-shaped chilidium bordering 

quadrilobate cardinal process. 

Interior of brachial valve with short cardinal 

process at posterior margin, supported by socket 

ridges that diverge at angle of 135°, tending to 

broaden and bifurcate shallowly. as they die out; 

four ridges of myophore meeting apically. Round pit 

of myophore present immediately in front of cardinal 

process. Median septum low near alveolus, becoming 

higher anteriorly and extending about two-thirds of 

distance across valve, fused posteriorly with pair of 

lateral septa that diverge at angle of 60° to each 

other and extend almost one-third of distance across 

valve. Middle part of valve has two raised elongate 

areas that continue diagonally from lateral septa, 

broaden slightly and die out in medio-lateral part 

of valve; between these and socket ridges are two 

subtriangular depressions, and another pair of depressions occurs between these raised areas and 

median septum. Rather thick endospines are closely 

scattered along anterior part of valve. 

Dimensions (in mm) .-

USNM USNM USNM USNM 1637:39 1637 40 163741 16374'2 

Length --------- 10.5 9.5 8.5 8.2 

Width ---------- 14.5 15.6 10.5 12.5 

Thickness ------- l 2.2 2.6 3.5 2.4 

1 Slightly c1·ushed specimen. All specimens from collection 157. 

Discussion.-The description above is based on 

our Wyoming shells. Measurements given in the 

table are for the four ·complete specimens figured 

on plate 1, which show some of the variations in 

shape found in this species. All are from the same 

locality on Berry Creek. The proportions of these 

shells are, in general, similar to those of Easton's 

specimens from the Cameron Creek Formation and 

Alaska Bench Limestone of central Montana 

(Easton, 1962), and they have about the same 

size range. Internal characters are similar, but 

those of Easton's figured specimens are a little more 

delicate and the endospines finer than in our figured 

Amsden shells. As the brachial valves figured by 

Easton are a little smaller than ours, these differences may be attributable largely to differences in 

growth stage. 

E. pseudoli1·atu.s is similar in shape and sculpture 

to E. ? suttoni (C. Branson) ; they may in fact be 

conspecific. Easton (1962, p. 45) separated the two 

on the basis of the large size and presence of a broad 

sulcus in E.? suttoni as opposed to the smaller size 

and absence of a sulcus in E. pseudoliratus. Our 

specimens of E. pseudoliratus are both with and 

without shallow sulci. As the internal characters of 

Branson's unique holotype are not known, whereas 

the characters of Easton's species are based on many 

specimens, we have chosen to retain Easton's name 

for the common Amsden species. Branson's form is 

discussed separately. 

Specimens from the Ranchester Limestone Member in western Wyoming are Early Pennsylvanian 

(Morrowan) in age. Specimens from the Horseshoe 

Shale Member at Berry Creek, Teton Range are 

shown by associated Foraminifera of Mamet's Zone 

19 to be latest Mississippian (latest Chesterian) in 

age. 

P.igured sped1nens.-USNM 163739-163745. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 153 (6), 157 (115), Teton 

County. Ranchester Limestone Member: collections 

67 (3), Sheridan County; ?97 (1), Lincoln County; 

133 (90), Sublette County; 141 (5), 142 (28), 

Teton County. 

Eolissochonetes? suttoni (C. Branson) 

Plate 1, figures 35-39 

Chonetes suttoni C. Branson, 1937, p. 656, pl. 89, figs. 8, 9. 

The holotype of this species is the only specimen 

definitely assigned to it. It is large for the genus, 

measuring (in mm) : length 13, width 20.5 (19.5 at 

midlength), and thickness 3.4. The shell is subrectangular in outline although more rounded anteriorly, concave-convex in longitudinal cross section. 

The pedicle valve is nearly flat posteriorly and becomes more convex toward the anterior margin. A 

shallow sulcus is present on the middle of the anterior slope. The auricular extremities are subangular, although one side has been rounded off by 

abrasion. The low interarea is inclined at 125° to 

the plane of commissure and is perforated medially 

by a triangular delthyrium partly covered apically 

by an indistinct pseudodeltidium. 

The brachial valve, is like the pedicle valve, nearly 

flat posteriorly but concave overall, the concavity 

greatest near the middle. A faint shallow fold corresponds to the sulcus of the pedicle valve. The 

interarea is low and inclined at approximately 70° to 

the plane of commissure. Its apical area is somewhat 

worn so that one has difficulty in telling whether a 

single chilidium or a pair of chilidial plates are 

present. The myophore of the cardinal process is 

quadrilobate but appears trilobate owing to the 

close spacing of the two central ridges. 

Both valves are smooth but have internal capillae, 

of which 28 to 30 occur in the space of 5 mm. Hinge 

spine bases are indistinct, but appear to be spaced 

about the same as on E. pseudoriratus. Because of 
BRACHIOPODA OF THE AMSDEN FORMATION D35 

the wider shall there may have been as many as 10 

of them. 

The unique specimen to which Branson attached 

the name Chonetes suttoni came from an undisclosed locality and horizon along the Little Popo 

Agie River, Wind River Range. Except for its large 

size, it generally resembles specimens from Berry 

Creek here referred to Eolissochonetes pseudoliratus 

(Easton). Its internal characters, however, are 

unknown. An attempt was made to bring out some 

of these by passing reflected light through the specimen while it was immersed in water. Although a 

lighter colored area was detected extending forward 

from the beak of the pedicle valve in the position 

of the median septum and its thickened base, no 

indications whatsoever were noted in the brachial 

valve, suggesting that it must be fairly thick. 

Because so much uncertainty exists as to the 

internal characters and even the provenance of this 

shell, it is regarded in this report as a species inquirenda. 

Type.-Holotype, UM 6832. 

Occurrence.-Hors~eshoe Shale Member ( ?) : collection 36d, Fremont County. 

Genus MESOLOBUS Dunbar and Condra, 1932 

Mesolobus sp. 

Plate 1, figures 31-34 

Desc1·iption.-Moderately small chonetid, having 

greatest width between hinge line and midlength. 

Pedicle valve moderately to shallowly -convex; in 

side profile, curvature greatest near midlength but 

almost imperceptibly so; in posterior profile, valve 

is convex in umbonal region and middle of arch but 

sloping rather straight toward and becoming gently 

concave near lateral margins. Sulcus broad and 

shallow, beginning about 2 mm in front of beak, 

gradually widening at about 30° angle toward anterior margin. Bottom of sulcus occupied by low, 

gently rounded median lobe weakly delimited from 

rest of sulcus. Surface smooth, appearing lirate 

where eroded, marked concentrically and irregularly 

by faint growth lines. Posterior margin having 

probably as many as seven spines on each side of 

beak. 

Brachial valve exterior not exposed. Interior of 

brachial valve having rather strong median septum, 

elevated anteriorly, bise-cting raised platform. Other 

details poorly preserved. 

Dimensions (in mm) .-

USNM 

1 16871.6 

Length --------------- 9.7 

Width --------------- 12.9 

Thickness ------------ 3.0 

USNM 

1 16371.7 

7.9 

13.5 

3.9 1 USNM 163746 and 163747 are from colleciton 15. ~ USNM 163748 is from collection 6. 

USNM 

2 163748 

7.5 

11.0 

2.6 

Discussion.-Eroded specimens show what appear 

to be capillae, particularly over the antero-medial 

part of the shell; toward the cardinal extremities, 

scattered tiny pits show through the shell or are 

exposed by weathering. Also, some subcircular clusters of what resemble lirae, actually beekite (silicification) rings, are developed locally where the shell is 

partly silicified. All these are secondary phenomena 

or are exposed by secondary phenomena and do not 

alter the fact that the shell surface in reality was 

smooth. 

The shaHow sulcu8, weak median lobe, and smooth 

surface of these shells suggest that they are closest 

to weakly sulcate forms of M esolobus meso lobus 

(Norwood and Pratten), as the type species of 

M esolobus is interpreted by Sturgeon and Hoare 

(1968, p. 31, pl. 6, figs. 1-24). M. mesolobus is common in rocks of DesMoinesian age in the American 

midcontinent Our specimens from rocks of Atokan 

age in the northern Rocky Mountain region are not 

well enough preserved to permit detailed comparisons with M. mesolobus. The consistently shallow 

sulcus and obsolete median lobe in the Wyoming 

specimens, as well as the difference in age, suggests 

that they may actually represent a closely related 

but distinct species. Other similar species that include specimens having an obsolete sulcus and median lobe are M. st1'iatus Weller and McGhee and 

M. obsoletus Sturgeon and Hoare. Both of these 

species differ from the Wyoming form in having 

longitudinal Urae ornamenting the surface of the 

shell. 

Figured specimens.-VSNM 163746, 163747. 

Measur·ed specimen.-VSNM 163748. 

OccuTrence and number of specimens.-Ranchester Limestone Member, collections 6 (2), 15 ( 4), 

Carbon County. 

Suborder PRODUCTIDINA 

Superfamily PRODUCTACEA Gray 

Family OVERTONIIDAE Muir-Wood and Cooper 

Genus SCOLOCONCHA Gordon, 1966 

Scoloconcha globosa (Mather ) 

Plate 3, figures 20-22 

Pustula globosa Mather, 1915, p. 167, 168, pl. 1:0, figs. 7-9'. 

Horridonia globosa (Mathe,r). Plummer, 1950, pl. 11, fig. 2. 

Scoloconcha globosa (Mather). Gordon, 1966, p. 584. 

Two small spinose productoids, in a collection 

from the Rawlins hills, are referred to Mather's 

species. The identifying characters of this species 

are the subhemispherical shape, incurved beak, and 

almost smooth surface bearing faint concentric 

growth lines and sparsely scattered spine bases. 

Dimensions of the more complete specimen (in mm) 

are: length 9.5, greatest width 9 (twice the half 
D36 THE AMSDEN FORMATION (MISSIS,SIPPIAN AND PENNSYLVANIAN) OF WYOMING 

width), and depth 5.5 mm. The hinge appears to be 

shorter than the greatest width, but the aural extremities are broken off so one cannot be sure. 

Comparison of the Wyoming shells with specimens 

of S. globosa from the Brentwood Limestone Member of the Bloyd Shale in the type region of the 

Morrowan Series in Washington County, Ark., indicates that they are conspecific. 

S. indianensis (Hall), the type species of Scoloconcha and only other described species thus far 

referred to the genus, can be distinguished from S. 

globosa by the elongate oval outline of its pedicle 

valve, shorter trail, less incurved beak, more spines, 

and slightly smaller size. 

Foraminifera of Mamet's Zone 20 from this same 

Amsden collection independently confirm its Morrowan age. This species is now known from Arkansas, Oklahoma, Texas, and Wyoming. 

Figured specimen.-VSNM 163790. 

Occurrence and number of specimens.-Ranchester Limestone Member: collection 13 (2), Carbon 

County. 

Family MARGINIFERIDAE Stehli 

Genus INFLA TIA Muir-Wood and Cooper, 1960 

lnllatia lovei n. sp. 

Plate 3, figures 1-9 

Dictyoclostus portlockianus (Norwood and Pratten). Burk, 

1954, p. 9, pl. 1, figs. 29, 30. 

Diagnosis.-SmaB to moderate-sized lnfiatia with 

or without shallow median sulcus in pedicle valve; 

ornamented by 12 to 14 costae in space of 10 mm on 

anterior slope and with scattered erect coarse spines 

near anterior margin. 

Description.-Shall elongate, subrectangular in 

outline, rounded posteriorly; widest just in front of 

hinge. Pedicle valve rather deep, convex; greatest 

curvature at umbo and decreasing gradually toward 

anterior margin; lateral slopes steep; ears not 

strongly differentiated; commonly without median 

sulcus, but where present sulcus is narrow, fairly 

shallow, beginning about 5 mm in front of beak and 

continuing on to anterior slope where, in some 

specimens, it dies out. Beak protruding a millimeter 

or two beyond hinge line. 

Sculpture on pedicle valve of low rounded costae 

separated by narrow intercostal grooves; six or 

seven costae occurring in space of 5 mm on anterior 

slope; some scattered costae more elevated than 

others, these generally bearing spines; costae increasing by bifurcation, very rarely by intercalation. 

Several concentric furrows present in posterior part, 

inclding umbonal region. Spines erect, as much as 

1.4 mm in diameter on anterior slope and 2 mm 

in diameter on flanks occurring ( 1) on coarser 

costae, 1.5 to 6.5 mm apart on a single costa and 

totaling about 25 in all near anterior margin, (2) 

two to three on flank just anterior to ear, and (3) 

in row of four or five along hinge at either side of 

umbo. 

Interior of pedicle valve with raised adductor 

muscle-scar platform beginning approximately 5 mm 

anterior to beak, roughly 10 mm long, 5 mm wide 

near posterior end, tapering to 3 mm near anterior 

end, as much as 3 mm high; entire adductor musclescar field appears dendritic. Diductor muscle scars 

in two fan-shaped areas at either side of adductor 

muscle-scar platform, each radially grooved and 

approximately 8 mm wide at anterior end. Area 

within ears smooth. Small endospines closely spaced 

over anterior part of visceral disc and within trail. 

Brachial valve concave, of moderate depth; ears 

fairly well differentiated from visceral disc by shallow folds; anterior edge of visceral disc rounding 

into trail or rather abruptly geniculate on some 

specimens; trail continuing at angle that ranges 

from 65 o to 80 o to floor of valve. Gentle median fold 

present on some shells, corresponding to sulcus of 

pedicle valve. Valve ornamented by costae as in 

pedicle valve; a few weak rugae present over visceral 

disc, particularly near sides. Spines not observed 

aup presumably absent. 

Interior of brachial valve having convex visceral 

disc produced into fairly short trail; cardinal ridges 

narrow, short, tilted posteriorly, and apparent only 

in immediate vicinity of posterior platform, merging 

with floor of valve about 3 mm laterally from cardinal process. Cardinal process short, sessile; myophore bilobate above and trilobate posteriorly. 

Posterior platform moderately broad, merging anteriorly with shallow end of pair of subtriangular adductor muscle-scar platforms; breviseptum emerging from between anterior raised edges of adductor 

muscle-scar platforms, higher and narrowing to 

knife edge anteriorly, extending forward to point 

about three-fifths of way across visceral disc. Each 

muscle-scar platform bearing dendritic posterior 

adductor muscle scar and, anterior to it, small area 

where anterior adductor muscle presumably attached. Brachial ridges take off near anterior ends 

of muscle-scar platforms, curving anteriorly, enclosing raised oval areas about 5 mm long and 3 mm 

wide. Interior of trail radially lirate; lirae bearing 

scattered short, anteriorly directed endospines, particularly in anterolateral areas. 
BRACHIOPODA OF THE AMSDEN FORMATION D37 

Dimensions (in mm) .-

Pedicle valves Brachial valves 

USNM USNM USNM USNM 163749 163750 163751 163752a 

Length --------------- 28 26 23 1 18 

L,ength along arch ----- 52 48 26 1 22 

Maximum width ------- 2 28 3 25 29 27 

Width of hinge ________ 24 23 2 26 25 

Depth ---------------- 16 16 9 1 5 1 Lacking small pa-rt of trail. All specimens from collection 4 7. 2 Estimated. 

a Twice the half width. 

Discussion.-This description is based principally 

on specimens from the Horseshoe Shale Member at 

Wiggins Fork (colin. 47), from which have been 

selected the holotype and nine paratypes. The calcareous she:lls at that locality are preserved somewhat imperfectly in fine sandstone, but all their 

salient characters can be seen. Also studied were 14 

specimens from Wiggins Fork in the collection of 

Yale University's Peabody Museum. Three of these 

have been designated as paratypes. Considerable 

variation in curvature is present in these specimens, 

the side profile of some pedicle valves showing fairly 

marked geniculation over the posterior part of the 

visceral disc. 

Specimens of I. lovei from Horse Creek in the collection of the University of Wyoming (colin. 43) 

have considerable variation in the depth of the sulcus, some lacking one altogether. The specimen 

having the deepest sulcus in this lot was figured by 

Burk (1954, pl. 1, figs. 29, 30) as Dictyoclostus portlockianus (Norwood and Pratten). Presence of some 

relatively large spine base scars that interrupt 

costae on the anterior slope of the pedicle valve in 

both sulcate and nonsulcate forms indicates that 

they represent only one species, and the differences 

in sulcation are due to individual variation. 

Infiatia infiata (McChesney differs from I. lovei 

in having a wider shell with a larger area of posterior slope and a much larger and deeper sulcus in 

the pedicle valve, more regular and fewer costae, 

and more steeply inclined trail in the brachial valve. 

The same characters differentiate I. bilobata Sadlick 

from this species, except that the spines in the Utah 

species approach in size those of I. lovei. 

I. spinolinearis (Easton) differs from I. lovei in 

being broader across the vault of the shell, having 

steeper flanks marked by a row of spines, the spines 

smaller, and a deeper brachial valve. I. obsoleta 

(Easton) differs from I. lovei in having a fairly 

smooth anterior slope, smaller spines, a more deeply 

concave brachial valve, and a wider adductor musclescar platform in the pedicle valve. I. confiuens (Easton) is differentiated by its smaller size, subparallel 

steep flanks, fairly prominent rounded sulcus, and 

confluent costae in the middle of the anterior slope. 

Types.-Holotype, USNM 163749; paratypes, 

163750-163753, 163791, YPM 20104a, g, h. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 21 (1), 43 (8), 44 (5), 45 

(27), 47 (40), 48 (14), Fremont County; 41 (7), 

Teton County. Ranchester Limestone Member: collection ?82 ( 6), Lincoln County. 

Genus RUGOCLOSTUS Easton, 1962 

Rugoclostus Easton, 1962, p. 59, 60. 

Description.-Medium-sized to moderately large 

productoids resembling semireticulate group in 

shape. Umbo smooth or ornamented only by concentric wrinkles. Costae and costeUae beginning in 

front of umbo and either extending to anterior 

margin or becoming obsolete or dying out entirely 

on anterior slope; rugae prominent in posterior 

part. Moderately coarse long spines scattered on 

both valves, except on umbones, commonly having 

a cluster on ears of brachial valve. Pedicle valve 

hinge having well-developed ginglymus. Pedicle interior having elongate oval dendritic adductor 

muscle scars on broad low elongate platform between pair of large diductor muscle scars. 

Brachial valve with large, fairly short, wide 

cardinal process having trilobate myophore, attached by short neck to posterior platform from 

which extend strong cardinal ridges. Adductor 

muscle scars set on thickened subtriangular platforms near posterior end of valve at either side of 

median septum ; brachial ridges prominent, enclosing raised thickened areas. Anterior part of visceral 

disc and trail studded wtih thick, fairly long and 

sharp endospines. 

Type species.-Rugoclostus nivalis Easton 1962, 

by original designation. 

Discussion.-This genus is recognized by its shape, 

somewhat like Infiatia, but is generally larger and 

has more prominent ears. Some of the smaller forms 

are very much like Infiatia but can be distinguished 

by their having spines on the brachial valve. The 

long posterior slope and prominent umbonal region 

in Rugoclostus also helps to distinguish this genus 

from Infiatia. The obsolete sculpture in the anterior 

part of some species of Rugoclostus is distinctive. 

The ginglymus present along the hinge in the pedicle 

valve, which was interpreted by Easton in the type 

species as a true interarea, is also a characteristic 

feature. 

At present only three species assignable to this 

genus are known. Besides the type species these 
D38 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

include Pt·oductus semistriatus Meek, 1860, and 

Rugoclostus williamsi n. sp. In addition to these, 

some undescribed species occur throughout the West. 

At least five species are present in the Great Basin. 

This genus is of particular interest because it seems 

to be restricted to western rocks of Morrowan age. 

It is not known, however, in the type region of the 

Morrowan Series in northwestern Arkansas. 

Rugoclostus williamsi n. sp. 

Plate 3, figures 10-18 

Diagnosis.-Moderate-sized Rugoclostus having 

well-developed costae on both valves that begin 

near umbo and continue to anterior margin; 10 to 

12 of these occur in space of 1 em on middle of 

anterior slope. Coarse spines sparsely distributed 

on pedicle valve; fine spines fairly common on brachial valve. 

Description.-Pedicle valve subhexagonal in outline, having wide hinge but even wider lateral margins so that greatest width is approximately twothirds of way from posterior to anterior margin. In 

side profile greatest convexity is at or near umbo, 

but convexity decreases a little unevenly posterior 

slope with areas of greater convexity giving faint 

geniculate appearance at points roughly 15 and 25 

mm, respectively, along arch from umbo; trail 

gently convex. Posterior profile having deep, almost 

V-shaped median sulcus flanked by well-rounded 

summits; flanks steep, becoming straight anteriorly. 

Median sulcus beginning as flat shallow depression 

8 mm in front of umbo and continuing to anterior 

margin, having steeply s:loping sides and narrowly 

rounded bottom on anterior slope. Posterior slope 

of umbonal region elongate; umbonal slopes steep, 

rounding rapidly into ears, diverging anteriorly at 

angle of 85°. Ears prominent, moderately long, 

highly arched, each set off by diagonal sulcus. Beak 

protruding about 2 mm beyond hinge line. 

Ornamentation of p'edicle valve consists of costae, 

concentric wrinkles, and spines. Umbo smooth; 

costae beginning 5 or 6 mm in front of umbo intercostal grooves of approximately same width as 

costae; costae increasing by bifurcation and tending 

to become fasciculate on flanks near anterior margin ; six or seven costae occur in space of 5 mm 

over posterior part of visceral disc where concentric 

wrinkles terminate, and five or six occur in same 

space on anterior slope. Concentric wrinkles weak, 

indistinct, limited to posterior one-third of valve, 

beginning about 5 mm in front of umbo, strongest 

on umbonal slopes; faint growth lirae also present. 

Spines are of two main types: (1) a row of fairly 

fine spine bases along hinge, directed posterolaterally; and (2) coarse suberect spines, as much as 1 

mm in diameter at base, scattered sparsely over 

shell; paratype (pl. 3, figs. 13, 14) has one of largest 

spines on ear near base of umbonal slope and another 

farther out on ear. 

Pedicle valve interior having raising adductor 

muscle-scar platform of arborescent appearance, 1 

em long, rising gradually in umbonal region, 7 mm 

in front of umbo, nearly 7 mm wide at posterior 

end, and narrowing to 5 mm near anterior end ; 

surface of platform fluted posteriorly by low rounded 

ridges that tend to coalesce anteriorly, nearly smooth 

near anterior end where two small depressions to 

which anterior pair of adductor musc,les probably 

were attached indent platform near its sloping anterior end. Diductor muscle scars longitudinally 

ridged, occupying rounded subtriangular depressions 

at either side of muscle scar platform, each 5 mm 

long by 7 mm wide. Anterior part of valve more 

coarsely ridged longitudinally, studded with small 

endospines. 

Brachial valve gently concave over visceral disc, 

rounded strongly along anterior edge of disc into 

nearly straight, moderately long trail, having broad 

shallow fold that corresponds to sulcus of pedicle 

valve. Ornamentation consists of costae like those 

on pedicle valve crossed, particularly over visceral 

disc by few weak concentric wrinkles and grooves. 

Small spines present on trail, emanating from costae, 

tending toward alinement in concentric rows, increasing abundance toward anterior margin. 

Interior of brachial valve poorly known. Cardinal 

ridges gently curved, fairly low, broadening slightly 

toward ears and dying out. Interior of trail studded 

with small prostrate endospines. 

Dimensions (in mm) .-

Length ------------------ Length along arch _____ ---

Maximum width ---------

Width of hinge ----------

Depth -------------------

1 Slight distortion by depression. 2 Twice the half width. 

USNM 

163751,. 

29.5 

60 

~ 32 

2 26 

21 

Pedicle 

valves 

USNM 

163755 

1 29 

53 

12 45 

!! 41 

1 16 

Brachial 

valve 

USNM 

163757 

25 

31 

2 35 

? 

11 

Discussion.-The description above is based upon 

material from collection 100, the best of which 

have been illustrated on plate 3. All specimens assigned to this species without question are from 

the Covey Cutoff section. They were collected by 

our colleague, the late James Steele Williams, for 

whom this species is named. 
BRACHIOPODA OF THE AMSDEN FORMATION D39 

A lot from the Ranchester Limestone Member in 

the Moffat Trail section (USNM 167719 from colin. 

83) , preserved as molds in chert, is identified as 

Rugoclostus cf. R. williamsi; one of them is figured 

(pl. 3, fig. 17). Valves are smaller than in the typical 

form, reaching widths of 22-27 mm. The costae over 

the visceral disc are moderately strong, and the same 

number occur in the space of 5 mm as in the typical 

form, but on the trail the costae become obsolete 

and tend to converge toward the sulcus as in "Dictyoclostus" confiuens Easton. 

Comparison of Easton's types of "D." confiuens 

with the Moffat Trail specimens shows that, although similar in appearance, they probably are not 

congeneric. "D." confiuens has no spines on the brachial valve and therefore belong in lnfiatia. In has 

sharper costae than the Moffat Trail form. Brachial 

valves from the Moffat Trail lot all show spines 

present. One has a poorly preserved but typical 

brachial interior, preserving beneath a secondary 

growth of tiny quartz crystals the remains of the 

median septum, one of the subtriangular adductor 

muscle-scar platforms, and one of the brachial 

ridges, as well as some moderately sparse endospines 

on the edge of the visceral disc and on the trail. 

Possibly these specimens represent a speeies of 

Rugoclostus distinct from R. williamsi, but in the 

absence of sufficient material to demonstrate the 

range of variation in R. williamsi, the Moffat Trail 

lot is regarded as only a local variant. Examination 

of hundreds of specimens of Rugoclostus from the 

eastern part of the Great Basin in Utah has shown 

that individual populations in this genus show a 

considerable range in shell ornamentation. 

R. williamsi looks very much like lnfiatia infiata 

(McChesney), the species exceedingly abundant in 

the Chesterian rocks of the American midcontinent. 

The Late Mississippian species, however, differs in 

having more subdued, gently rounded costae, a 

shallower, slightly narrower sulcus, greatest width 

at or near the hinge and no spines on the brachial 

valve. 

From Rugoclostus nivalis Easton our Wyoming 

species differs in having stronger costae, none of 

which disappear entirely on the trail, and more 

sparsely distributed coarser spines. Rugoclostus 

sem1~striatus (Meek), described originally from a 

locality near Provo, Utah, is a slightly smaller 

species having only a faint suggestion of a sulcus. 

Over the visceral disc about nine costae and costellae 

occur in the space of 5 mm; all of them become obsolete and disappear on the trail. 

Types.-Holotype, USNM 163754; paratypes, 

USNM 163755-163757. 

Figured specimen.-USNM 167719. 

Occ~wrrence and number of specimens.-Ranchester Limestone Member, USGS collections 83 [cf.] 

(4), 94 (2), 99 (1), 100 (11), Lincoln County. 

Family PRODUCTIDAE Gray 

Genus DIAPHRAGMUS Girty, 1910 

Diaphragmus cestriensis (Worthen) 

Plate 4, figures 1-4, 15-20, 22 

Productus elegans Norwood and Pratten, 1854, p. 13, pl. 1, 

figs. 7a-c [not P. elegans McCoy, 1844] ; Sutton, 1938 

[part], p. 559, pl. 64, fig. 12 [not figs. 9-11]. 

Productus cestrie-nsis Worthen, 1860, p. 570 [new name for 

P. elegans Norwood and Pratten, not McCoy]; Ke.yes, 

1895, p. 44; Easton, 19·42 [part], pl. 4, figs. 8, 9 

[nOit fig. 10]. 

Diaphragmus elegans (Norwood and Pratten). Girty, 1910, 

p. 217; Weller, 1914 [part], p. 136-138, pl. 12, figs. 

13-17 [not figs. 8-12]; Snider, 1915 [part], p. 84; 

Girty, 1915h, p. 59, pl. 3, figs. 5, 5a; Ulrich, 1917, p. 

252, pl. 4, figs. 32-40; Butts, 1926 [part], p. 198, pl. 

65, figs. 6, 7 [not figs. 8, 9]; Haas, 1946, p. 5; Elias, 

1957, p. 50·5-509, text figs. 7-9. 

Diaphragmus (Productus) elegans (Norwood and Pratten). 

Butts, 1917, p. 80, pl. 21, figs. 30-33. 

Diaphragmus motesanae [sic] Ulrich, 19•17, p. 252, pl. 4, 

figs. 25-31 [not figs. 1-24]. 

Diaphragmus cestriensis (Worthen). Croneis, 1930 [p•art], 

p. 74, pl. 19, figs. 20, 21 [not p. 54, pl. 13, fig. 10]; 

?Cooper, in Shimer and Shrock, 1944 [part], p. 349, 

pl. 135, :figs. 4.2, 43 [not figs. 44, 45]; Muir-Wood and 

Cooper, 1960 [part], p. 242, pl. 73, fig. 18 [not figs. 

1-17]. 

Diagnosis.-Relatively small Diaphragmus having 

narrow pedicle valve and trail of moderate length, 

ornamented principally by 30 to 36 costae and costellae and numerous scattered spines, including spine 

patch on flanks near ears. Initial part of visceral 

disc in brachial valve subcircular. 

Discussion.-Girty (1910, p. 217, 218) designated 

Pro ductus elegans Norwood and Pratten as the type 

species of his new genus Diaphragmus and called 

attention to Worthen's substitution of the name 

cestriensis for Norwood and Pratten's name. Elias 

(1957, p. 505) regarded Productus fasciculatus McChesney as the type species because he believed the 

specimens that Girty actually had in hand when he 

described the genus Diaphragmus belonged in McChesney's species. Such an interpretation is not, 

however, compatible with Article 68 (a) of the 

International Code of Zoological Nomenclature 

(Internat. Comm. Zool. Nomenclature, 1961). 

D. elegans and D. cest1·iensis have long been used 

as catch-all names for members of the genus Diaphragmus. Some authors have regarded D. fasciculatus as a synonym of D. cestriensis. As used in this 
D40 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

paper, the name D. cestriensis is applied rigidly to 

th'e rather small diaphragm-bearing productid 

species origina,1ly described as Productus elegans 

by N orwod and Pratten. This species is characterized by the nearly circular visceral disc in the brachial valve, the absence of a sulcus in the pedicle 

valve and in having 35 or less costae and costellae, 

the smallest number in any Diaphragmus now recognized. 

Specimens from the Moffat Trail Limestone l\iember in Hoback Canyon are almost identical in all 

respects with specimens from Chesterian rocks in 

the Illinois basin. The Wyoming shells are strongly 

convex, particularly in the posterior part; on some 

the umbonal region is rather elongate. Two typical 

pedicle valves are illustrated (pl. 4, figs. 1-4, 15-

18), also a poorly preserved brachial-valve interior 

showing relatively large adductor muscle-scar platforms (pl. 4, fig. 19), and a partly decorticated 

brachial valve showing the diaphragm area (pl. 4, 

figs. 20, 22). Costae and costellae number 30 to 35 

on these specimens and average 33. Spines ornament 

all costae, are spaced 2 to 4 mm apart on individual 

costae, and occur as close together as 1 mm apart 

on adjacent costae. Spine patches on the flanks of 

these shells generally contain as many as 30 spine 

bases. Dimensions of three pedicle valves and one 

brachial valve are as follows. 

Dimensions (in mm) .-

Brachial 

Pedicle valves valve 

USNM USNM USNM USNM 163764 163766 163767 163765 

Length --------- 18.8 15 14 12 

Length along arch 34 27 28 1 14.5 

Maximum width _ 15 13 14.5 13 

Width of hinge __ 12.5 11.2 211 11 

Depth ---------- 11 10.2 10 3 1 Trail not complete. The trail of the first specimen is about 8 mm long. ~ Twice the half width. 

Another lot, from Covey Cutoff (colin. 93), differs 

slightly from the Hoback Canyon specimens in the 

presence of small rugae on the lateral slopes in the 

posterior part of the shell. These specimens are regarded as local variants of D. cestriensis. 

This species is widely distributed in the Chesterian rocks of the American midcontinent. It is 

present in the Paint Creek Formation and ranges 

upward through the Menard and higher Chesterian 

formations of Illinois and Kentucky. In Arkansas 

this species is absent in the Batesville Sandstone 

and also seems to be missing in the Fayetteville 

Shale, but it is ·relatively common in the Pitkin 

Limestone. Its presence in the Moffat Trail Limestone Member of the Amsden Formation is in beds 

that are in general equivalent to the Pitkin Limestone. Such a distribution suggests that in late 

Chesterian time this species broke out of the Illinois basin and became widely distributed in regions 

to the southwest and west. Typical D. cestriensis is, 

however, not known in the Great Basin region of 

Utah and Nevada. 

Figured and measured specimens.-USNM 

163710, 163764-163767. 

Occu'rrence and number of specimens.-Moffat 

Trail Limestone Member: collections 93 (35 ±), 

Lincoln County; 120 (1), 121 (14), 122 (31), Teton 

County. 

Diaphragmus nivosus n. sp. 

Plate 4, figures 5-14 

Productus fasciculatus McChesney. Easton, 1962, p. 48, 49, 

pl. 6, figs. 1a-5b. 

Diagnosis.-Broad low shallowly sulcate Diaphragmus having wide hinge and moderately short 

trail. Ornamentation of 40 to 75 costae and costellae 

on both valves; rather coarse spines sparsely scattered on pedicle valve, including concentration of as 

many as 12 spines on each flank near ears. 

Description.-Pedicle valve small to moderatesized, subcircular to subtrapezoidal in plan; greatest 

width at or near hinge. Side profile with greatest 

curvature near umbo, decreasing anteriorly, but 

rather strongly convex just posterior to middle of 

visceral disc, giving faint geniculate aspect; anterior slope straight or nearly so. Posterior profile 

showing shaHow sulcus over middle of valve, 

bounded by convex summits that round into nearly 

straight steeply inclined flanks; sulcus beginning 

within 1 em of umbo, normally continuing and 

broadening somewhat to anterior margin, but on 

some specimens dying out on anterior slope. Urnbona! flanks diverging at angles of 90° to 95°, but 

sloping off toward and merging with slightly arched 

ears; cardinal extremities forming acute angle. 

Umbo protruding slightly across hinge with little 

in curving. 

Ornamentation of pedicle valve consisting of low, 

broadly rounded costae and costellae, separated by 

slightly narrower rounded intercostal grooves; six to 

nine occurring in space of 5 mm on anterior slope. 

Costae and costellae increasing by bifurcation, with 

some irregularity and tending toward fasciculation; 

some costae coalesce anteriorly, particularly in front 

of large spine bases. Concentric sculpture consisting 

of weak rugae on posterior part of valve, largely 

confined to umbonal slopes and flanks, weaker to 

absent over middle of vault; fine concentric growth 

lirae also present. Spines occur (1) in single row 
BRACHIOPODA OF THE AMSDEN FORMATION D41 

along hinge at either side of umbo, generally directed 

posterolaterally; (2) scattered rather sparsely over 

surface of shell, emanating from costae, spaced 6 to 

8 mm apart on anterior slope; and (3) in meager 

concentration of as many as 12 spines on flanks near 

ears. 

Interior of pedicle valve having adductor musclescar platform consisting of low subparallel ridges, 

bisected by narrow median groove; platform is approximately 1 em long and 3 mm wide, widest in anterior part, terminating roughly 15 mm in front of 

umbo. Diductor muscle scars at either side of platform longitudjnaUy grooved and fluted, beginning 

about 8 mm in front of umbo, occupying subtrapezoidal areas approximately 6 mm long and a maximurn of 5 mm wide, not strongly differentiated from 

costation of shell. Endospines short, sharp, and 

closely spaced within anterior part of visceral disc 

and trail. 

Brachial valve geniculate, almost flat over visceral 

disc, bent sharply at intervals within diaphragm 

area to form several trails; innermost trail approximately straight, strongly inclined; outermost nearly 

at right angle's to visceral disc, of moderate length 

(6-10 mm long in adult shells). Umbonal region 

slightly depressed along flexures that diverge from 

apex at 70°; gentle indistinct fold usually present 

on anterior part of visceral disc and on outer trails. 

Ears sloping more steeply than visceral disc and 

set off from it and from flanks of innermost trail by 

short diagonal ridge. Visceral disc wider than long; 

width of diaphragm area ranging from one-fourth 

to two-fifths length of visceral disc. 

Costation on brachial valve similar to that of 

pedicle valve but without tendency toward fasciculation. Rugae indistinct, confined to lateral parts of 

visceral disc. Spines rare but scattered spine bases 

occur on innermost trail, spaced 3 mm and farther 

apart, also on ears. 

Interior of brachial valve having short stout cardinal process, bilobate above and trilobate posteriorly. Small pit or alveolus present in some specimens or faint elongate depression where shaft meets 

posterior platform. Cardinal ridges straight, dying 

out laterally just short of diaphragm area. Adductor 

muscle-scar platforms subtriangular, thick; posterior part bearing dendritic posterior pair of musclescar impressions, slopes backward gently; anterior 

part extends forward in two smooth tapering lobes 

to which anterior pair of adductor muscles attached. 

Medium septum either passes weakly between adductor muscle-scar platforms or emerges as breviseptum 

from between their anterior lobes; in front of platforms, septum is bladelike, reaches height of 2.1 mm, 

and extends across smooth diaphragm area to anterior edge of visceral disc. Brachial ridges faint; 

prostrate endospines present on anterior part of 

visceral disc, also within trail. 

Dimensions (in mm) .-

Brachial 

USNM 

Pedicle 

USNM 

valves 

USNM ~ 

USNM 163758 118763A 118764 16.1759 

Length ---------- 23 24.5 21 20.5 

Length along arch _ 39 42 36 24 

Maximum width -- 1 27 1 25 1 24 1 26 

Depth ------------ 13 13.5 12.5 6.5 

' Twice the half width. 

D1:scussion.-This species is based upon Easton's 

specimens of "PToductus fasciculatus" from the 

Heath Formation in the Big Snowy Mountains of 

central Montana. The holotype (USNM 163758) is 

a shell that Easton did not figure; his figured specimens are regarded as paratypes, as are six additional specimens from the type locality (USGS colln. 

13425-PC). 

External characters and those of the interior of 

the pedicle valve in the description above are based 

on material from the type locality. Internal characters of the brachial valve are derived principally 

from specimens figured by Easton (USNM 118761, 

118762) from two other localities. The holotype 

and a paratype, a brachial valve from the type 

locality, are figured on plate 4, figures 5-7, 12-14. 

Specimens of D. nivosus from a locality in the 

Horseshoe Shale Member in western Wyoming are 

figured on plate 4, figures 8-11. The Wyoming 

specimens have the broad shell, shallow sulcus, low 

convex costae and costellae with narrow intercostal grooves, sparsely scattered spines, and transverse visceral disc that characterize the Montana 

species and are clearly conspecific with it. 

Diaphragmus nivosus is closest in shape and costation to D. fasciculatus McChesney, which has a moderately broad shell indented by a shallow median 

sulcus in the pedicle valve, a transverse visceral disc 

in the brachial valve, and a similar range of the total 

number of costae and costellae on both valves. D. 

nivosus differs, however, in having a lower shorter 

shell bearing far fewer spines. On typical D. fasciculatus from the Mississippi Valley, more than 200 

spines may occur on the pedicle valve, including 

patches of 35 to 40 spines on each flank. On D. nivosus, the two spine patches will not add up to a~ 

much as 30 spines, and the total number on the 

pedicle valve rarely, if ever, reaches 70. 

D. nivosus differs from D. cestriensis (Worthen) 

in having a broader shell, a median sulcus in thE 
D42 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

pedicle valve, transversely oval to subrectangular 

visceral disc in the brachial valve, and greater number of costae and coste1lae and notably fewer spines 

on both valves. 

In its character of having relatively few fairly 

coarse spines scattered over the surface of the shell, 

D. nivosus also resembles Carlinia diabolica Gordon, 

a productid common in the latest Late Mississippian 

of Utah and Nevada. D. nivosus is, however, a true 

Diaphragmus, which differs from Carlinia in possessing well-developed trails in the brachial valve in 

place of numerous frills, spines on the brachial valve, 

a clearly differentiated diaphragm area on the interior of the brachial valve, and a spine patch on each 

flank of the pedicle valve. 

Types.-Holotype, USNM 163758. Paratypes: 

USNM 118761; 118762; 118763A-C; 118764A, B; 

163770 (totaling 13 specimens). 

Figured specimens.-USNM 163758, 163759, 

163768, 163769. 

Occurrence and nwtnber of specitne-ns.-Horseshoe 

Shale Member: collection 41 (8), Teton County, 

Wyo. Primary types are from the Heath Formation, 

USGS collections 13409-PC (1 paratype), Fergus 

County; 13414-PC (3 paratypes), 14325-PC (bolotype and 9 para types) , Golden Valley County, 

Mont. See Easton (1962) for locality data. 

Genus CARLINIA Gordon, 1971 

Carlinia amsdeniana Gordon 

Plate 4, figures 21, 23-37 

/Jiaphragmus phillips·i (Norwood and Pratten) Branson and 

Greger, 1918, p. 314, pl. 19, figs. 5, 6. 

Pastula genevievensis (Weller). Branson and Greger, 1918, 

pl. 19, fig. 2 [not p. 315, 316, pl. 19, fig. 1]. 

Marginije1·a muricatina Dunbar and Condra. Burk, 1954, p. 

10, 11, pl. 1, figs. 26-28. 

Carlinia amsdeniana Gordon, 1971, p. 261, 262, pl. 1, figs. 

9-13, 22, 23. 

Diagnosis. - Subpentagonal productid having 

length roughly equal to width; pedicle valve generally with V-shaped median sulcus, surface ornamented by 24 to 35 costae and costellae and numerous scattered spines, including about 20 in area of 

hinge and ear. Brachial valve ornamented laterally 

and anteriorly by many short concentric frills. 

Description.-Pedicle valve having greatest 

width usually at ears just in front of hinge. Valve 

convex throughout longitudinal profile; curvature 

greatest at umbo, decreasing a little unevenly but 

gradually toward anterior margin. V-shaped median sulcus (not quite central in holotype) present 

across hinge; in other specimens, area of sulcus is 

in some specimens, commonly beginning less than 

5 mm in front of beak, which protrudes slightly 

across hinge ; in other specimens, area of sulcus is 

merely flattened or slightly depressed. Anterior and 

lateral slopes diverging toward margins. Umbonal 

slopes steep, diverging anteriorly at angle of roughly 

110°, and curving outward gradually so that ears 

are only moderately delimited by broad diagonal 

sulci. 

Surface of pedicle valve ornamented by somewhat 

irregular and subequal costae interspersed locally 

with costellae, generally averaging 30 in all but 

ranging from 24 to 35 in various specimens. Costae 

increasing by bifurcation, some tending toward 

fasciculation anteriorly. Rugae absent or merely 

suggested by two or three faint concentric ridges 

in umbonal region in some specimens; concentric 

growth Iirae not prominent. Spine bases abundantly 

scattered over valve (1) on top of costae, commonly 

1 to 2 mm apart over anterior slopes and 2 to 2;4 

mm apart along individual costae, (2) in two rows 

or six or seven spine bases at either side of umbo, 

one along hinge margin, the other just in front at 

very low angle diagonal to hinge, extending on to 

ears, and (3) merging with cluster of about 12 to 

15 spines scattered over umbonal and lateral slopes 

near ears. 

Interior of pedicle valve (pl. 4, fig. 24) having low 

medial platformlike structure beginning 2 or 3 mm 

in front of umbo, as much as 3 mm wide, composed 

of two elongate smooth lobes divided by low median 

ridge; adductor muscle-scar area begins at its anterior end, occupying space 4 mm long and 1.3 to 1.7 

mm wide between diductor muscle scars. Posterior 

pair of adductor muscle scars narrowly dendritic, 

diverging slightly posteriorly; anterior pair nearly 

smooth, situated in elongate parallel depressions 

opposite anterior parts of diductors. Diductor 

muscle scars occupying transversely oval longitudinally !irate areas 4 X 5 mm across, beginning 4 

or 5 mm in front of beak. Rest of pedicle interior 

weakly costate; no endospines visible. 

Brachial valve transversely subrectangular in outline, gently concave medioposteriorly, a little less 

concave in lateral areas a short distance in front of 

ears; also concave near anterior margin, except medioanteriorly where shallow fold, commonly present, 

corresponds to sulcus of pedicle valve. Surface ornamentation of fine radial costellae limited to initial 

part of valve, which is bounded by single tiny concentric frill approximately at middle of valve. Two or 

three more such frills with wide but gradually narrower interspaces surround first frill, and just within 

margin of valve is band of 7 to 10 concentric wavy 

frills; all appear to represent trails that never fully 

developed. 
BRACHIOPODA OF THE AMSDEN FORMATION D43 

Interior of brachial valve (pl. 4, figs. 21, 25) 

having transversely suboval visceral disc bordered 

posteriorly by fairly short cardinal ridges that curve 

somewhat posteriorly at either side of cardinal process and die out laterally. Cardinal process short, 

typical of genus, but details of myophore not known. 

Posterior platform poorly defined high area that 

merges anteriorly with pair of low lobate adductor 

muscle-scar platforms, slightly raised anteriorly. 

Emerging from between platforms, breviseptum extends almost to margin of visceral disc. Faint linear 

brachial ridges beginning near muscle-scar platforms at angle of 75° to breviseptum, forming 

loop extending laterally and slightly forward, reaching edge of visceral disc anterolaterally. Short prostrate endospines in band along anterior margin of 

valve. 

Dimensions (in 1nm) .-

H olotype ----c~=-=-P_a_ra...:...::ty:..o_p_:es~-=-------,--

1 UM2645 2 USNM 163760 UM 2645 

Length --------------- 25.1 23.5 18.5 

Length along curvature 41.0 40.5 32.5 

Greatest width -------- 25.0 23.5 20.9 

Width of hinge ______ 22.5 18.5 19.2 

Depth ---------------- 13.3 12.5 9.7 

1 UM 2645 is from collection 36a. 2 USNM 163760 is from collection E. 

Discussion.-The description above is slightly 

modified from the original one, the greatest change 

being the addition of the internal characters of the 

brachial valve from a prepared topotype (colin. 27). 

Two forms of this species are present in the Wind 

River Range. In the typical form (pl. 4, figs. 30-37), 

the narrow sulcus divides the vault of the shell into 

two rounded summits. In the nonsulcate form, the 

vault is rather flat across the top, curving abruptly 

into the sloping flanks. This gives the shell a distinctly trapezoidal aspect in posterior profile (pl. 4, 

figs. 26-20). 

Gordon (1971) has pointed out the incorrect referral by Burk (1954) of two specimens of C. amsdeniana to the Middle Pennsylvanian (Des Moinesian) species Marginifera mu1·icatina Dunbar and 

Condra. Burk's figured specimens have been reexamined. Both show the diaphragm area, which 

also can be seen in one of Burk's illustrations (Burk, 

1954, pl. 1, fig. 28). 

The species closest to C. amsdeniana is C. phillipsi 

(Norwood and Pratten), to which Branson and 

Greger (1918) originally referred the Wyoming 

form. C. phillipsi has fewer and coarser ribs and 

spines and a narrower hinge than C. amsdeniana, 

and it does not develop a V-shaped median sulcus in 

the pedicle valve, although it commonly possesses a 

broad shallow sulcus or medial flattening in this 

valve. 

StTatigr·aphic considerations.-C. amsdeniana is 

restricted to a single subzone, to which it gives its 

name, near the middle of the Horseshoe Shale Member in Fremont County. At Livingston Ranch it occurs in association with Formanifera of Mamet 

Zone 18. This agrees with the stratigraphic position 

of C. phillipsi in the Great Basin near the UtahNevada border, which occurs stratigraphically above 

beds containing corals of the Caninia Zone and below 

uppermost Mississ,ippian beds containing Foraminifera of Mamet Zone 19. 

Types.-Holotype and paratype, UM 2645; additional paratypes, USNM 163760-163763; hypotypes, 

UW A11094, A11119. 

Burk's figured specimens.-VW IT-197, IT-198. 

OccuTrence and nu1nber of specimens.-Horseshoe 

Shale Member : collections 22 ( 10 + fragments) , 26b 

( 3), 27 ( 11) , 28 ( 8) , ?29 ( 1), ?30 ( 1), 31 ( 6), 36a 

(29), 39 (3), 44 (2), 45 (2), 48 (2), E (27), Fremont County. 

Family ECHINOCONCHIDAE Stehli 

Genus ECHINOCONCHUS Weller, 1914 

Echinoconchus sp. A 

Plate 3, figures 19, 23, 24, 31, 32 

Echinoconchus aff. E. alternatus (Norwood and Pratten). 

Easton, 19·62, p. 48, pl. 4, figs. 28a, b. 

Rugoclostus nivalis Easton, 1962 [part], p. 60, 61, pl. 7, figs. 

15a-d [not figs. 11-14]. 

Description.-Shell moderately large; pedicle 

valve subcircular in outline, greatest width occurring a little anterior to middle. Convexity in side 

profile greatest near umbo, decreasing gradually 

anteriorly, but continuing moderately convex to 

anterior margin. Subtrapezoidal in posterior profile) 

depressed over center, rounding strongly into sloping flanks that are very gently convex. Median part 

of valve flattened anteriorly over center and forming 

very shallow broad sulcus on anterior slope. Umbonal 

region elevated; umbo strongly incurved over hinge; 

umbonal slopes convex, very steep, diverging forward at angle of about 85°. Ears rather steeply 

inclined both posteriorly and laterally, merging with 

umbonal slopes. Interior of pedicle valve not known. 

Ornamentation of pedicle valve consisting mainly 

of gently convex concentric ridges separated by narrow grooves, three to four ridges occurring in space 

of 1 em on middle of anterior slope; bands narrowing and becoming slightly more elevated on flanks. 

Each concentric band bearing two or three rows of 

small spine bases from which emanate tiny forwarddirected spines. 
D44 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Brachial valve broadly oval to subquadrate in 

outline, gently concave, having very gentle broad 

poorly delimited median fold in anterior half; no 

apparent trail. Ornamentation of low concentric 

ridges, grooves, and spine rows as on pedicle valve, 

except that spacing tends to be closer, ridges averaging about 10 in 1 em. 

Interior of brachial valve with moderate-sized 

bilobate cardinal process, curving downward into 

beak of pedicle valve· posteriorly. Cardinal ridges 

narrow, slightly recurved toward ·cardinal extremities. Posterior platform elevated above floor of 

valve, elongate, rounded above, merging anteriorly 

with adductor muscle-scar platforms which extend 

forward as a pair of narrow raised lobes; adductor 

muscle-scar impressions not identifiable. Breviseptum narrow, extending from between muscle-scar 

platforms to point that is little more than halfway 

forward across valve. Anterior part of visceral disc 

bearing short prostrate endospines ranged along 

weak concentric ridges. 

The figured nearly complete specimen (USNM 

163788) which lacks a small part of the anterior 

margin has the following measurements (in mm) : 

length 51, length along arch 95, maximum width 50 

(twice the half width), width of hinge 36 (twice 

the half width), depth 30; its brachial valve is 

approximately 36 mm long and 4 mm deep. 

Discussion.-Eleven specimens from six localities 

in the Rawlins hills are included under this title. 

They probably represent the same speeies illustrated 

by Easton (1962, p. 48) as "Echinoconchus aff. E. 

alte1·natus (Norwood & Pratten)" from a locality in 

the Cameron Creek Formation or Alaska Bench 

Limestone near Heath, Mont. 

One of the paratypes of Rugoclostus nivalis Easton (1962, pl. 7, figs. 15a-d) also belongs in Echinoconchus and almost certainly in the same species that 

Easton illustrated from near Heath. The specimen 

in question (USNM 118790, from USGS colin. 

13420-PC) consists of the posterior part of a pedicle 

valve and the cardinal process that was found 

imbedded in it and presumably came from the 

brachial valve of the same she!l. The cardinal 

process is of a type of characteristic of Echinoconchus. The exterior of the pedicle valve, consisting of 

little more than the umbona.J region, is ornamented 

by concentric bands, each bearing two or three 

rows of fine spines, the typical spine arrangement 

in Echinoconchus and particularly in E. sp. A. 

The distinguishing characters of Echinoconchus 

sp. A are its very weak sulcate pedicle valve having 

a prominent overhanging beak; the concentric spinebearing ridges or slightly raised bands separated by 

narrow grooves, three to four occurring in the space 

of 1 em on the middle of the anterior slope. The 

interior of the brachial valve is characterized by the 

prominent adductor muscle-scar platforms, merging 

posterior platforms, and the presence of a breviseptum. 

Echinoconchus alternatus (Norwood and Pratten) differs from E. sp. A in having a smaller shell, 

its pedicle valve ornamented by broad, moderately 

deep concentric depressions separated by narrow 

ridges, each depression bearing two or three alternating rows of spines with long spine bases; two 

depressions and two or three ridges generally occur 

in the space of 1 em on an average specimen. 

E. vittatus (HaH), which some workers have 

placed in synonymy with E. alternatus, has narrower 

concentric depressions but more spines, four or five 

rows occurring within a single concentric band; 

about three concentric depressions and ridges occur 

in the space of 1 em on the middle of the anterior 

slope, becoming more crowded toward the anterior 

margin. The beak is shorter and less incurved than 

that of E. sp. A, and the median sulcus in the 

pedicle valve is well defined. Within the brachial 

valve of E. vittatus, a median septum extends forward from the cardinal process, a~Ithough it may be 

partly covered with secondary shell material in old 

age, and the adductor muscle-scar platforms are 

ill-defined longitudinal lobes. 

It seems likely that Echinoconchus sp. A. represents an unnamed species, but our materia~! is not 

quite well enough preserved to serve as primary 

type specimens. 

F1~gured specimens.-USNM 163788, 163789. 

Occuyrence and number of specimens.-Horseshoe 

Shale Member: collections 1 (1), 3 (4), 5 (2). Ranchester Limestone Member: collections 6 (2), 13 

(1), ?14 (1), Carbon County. 

Family BUXTONIIDAE Muir-Wood and Cooper 

Genus FLEXARIA Muir-Wood and Cooper, 1960 

Flexaria sp. 

Plate 3, figures 28-30 

Pustu1a genevievensis (Weller). Branson and Greger, 1918, 

p. 315, 316, pl. 19, fig. 1. 

A pedicle valve, figured by Branson and Greger, 

is the only undoubted Flexaria known from the 

Amsden Formation. The shell is 23.3 mm long, 25.5 

mm wide, and 12.0 mm deep. The hinge line, broken 

at its extremities, is not quite 17 mm long; it is 

estimated to have been approximately 19 mm in 

length. The valve has the characteristic roundedsubtrapezoidal outline of Flexaria, the greatest width 
BRACHIOPODA OF THE AM8DEN FORMATION D45 

occurring slightly anterior to the middle. The umbo 

protrudes a millimeter or two beyond the hinge; the 

greatest convexity in side view is near the umbo, 

particularly at points 5 and 9 mm, respectively, 

anterior to the tip; the rest of the valve is rather 

regularly convex to the anterior margin. The apical 

angle is approximately 110°, and the lateral slopes 

diverge at an angle of 65°. In posterior view, the 

valve is rather flat over the visceral disc, and the 

lateral slopes are steep. What resembles a shallow 

ventral sulcus in the posterior part of the valve 

appears to be in part pathologic; no marked sulcus 

is present on the anterior half of the valve, but a 

faint slightly asymmetric depression indents the 

anterior margin. 

The surface of the shell is ornamented by about 

55 rounded costae and costellae; near the anterior 

margin an average of 7 of these occur in the space 

of 5 mm. Costae and costeUae are thickened locally, 

particularly where they give off anteriorly directed 

spines ; some of the spine bases near the anterior 

margin tend to be alined in concentric rows. 

Only figure 1 of the two figures that Branson and 

Greger (1918, pl. 19, figs. 1, 2) identified as Pustula 

genevievensis (Weller) is actually a view of this 

shell. The other figure so labeled (fig. 2) is a side 

view of the productoid they also illustrated in figure 

5 of the same plate, which they identified as Diaphragmus phillipsi (Norwood and Pratten) and 

which has since been designated the holotype of 

Carlinia amsdeniana Gordon. 

Presence of costae and absence of concentric 

ridges preclude assignment of this shell to Echinoconchus, the genus to which "Pustula" genevievensis 

(Weller) originally was and should presently be 

referred. Resemblance of this Amsden shell is closer 

to Juresania than to Echinoconchus because of its 

concentric rows, but the more or less continuous 

costae and the relatively small number of concentric 

grooves is more compatible wtih Flexaria. Another 

specimen, from Livingston Ranch, is referred with 

question to Flexaria. 

Figured specimen.-VM 2646. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 36a (1), ?45 (1), Fremont County. 

Genus JURESANIA Fredericks, 1928 

Juresania sp. 

Plate 3, figures 25-27 

This record is based on seven specimens in six 

collections. The figured pedicle valve (USNM 

163772) is 23.5 mm long, 25 mm wide near the 

anterior end, and 12.5 mm deep. The hinge appears 

to have been somewhat narrower than the widest 

part of the shell. In side elevation the greatest 

curvature is at the umbo; the convexity decreases 

gradually toward the anterior margin. In posterior 

view, the valve is flat to slightly depressed over the 

visceral disc and rounds rapidly to the lateral slopes, 

which are very steep. A broad shallow median 

sulcus begins about 10 mm in front of the umbo 

and continues to the anterior margin. The sides 

of the umbo diverge at about 90°, and the lateral 

slopes, at 70°. 

Surface sculpture in the pedicle valve consists of 

slightly concave concentric bands bordered by narrow shallow ridges. These bear elongate spine bases, 

many of which resemble interrupted costae; six or 

seven of these occur in a space of 5 mm on the 

anterior slope. Spines emanate in a single row near 

the anterior edge of each concentric band. Near the 

anterior margin the spines are somewhat random 

in their distribution. On a fragmental pedicle valve 

(USNM 163773) better preserving the sculpture of 

the posterior part of the shell, the concentric bands 

are narrow and more numerous, and the spine bases 

emanate from single rows of shallow nodes ranged 

along the concentric ridges. 

The figured brachial valve (USNM 163771) is 

fairly flat, having a faint shallow median fold 

externally on its anterior half and a short trail. 

It is 19 mm long, 23 mm wide, 3 mm deep, and its 

hinge is 18 mm long (determined as twice the half 

width). Its interior is well preserved as a mold in 

dolomite. The cardinal ridges are narrow and fairly 

shallow, diverging in a broad obtuse angle from the 

base of the cardinal process. A pair of short longitudinal ridges or buttress plates with an elongate 

antron between them support the cardinal process 

(which is missing in this specimen) . Immediately 

in front of these the posterior platform is narrow, 

slightly elevated, and gives rise to a short breviseptum that bisects a pair of elongate lobate musclescar platforms, slightly raised anteriorly; these 

extend forward to a point about two-fifths of the 

way across the visceral disc. Anterior to this, a 

series of six concentric ridges bears one or two 

rows each of small endospines. Brachial ridges are 

not visible. 

The specimens referred here to Juresania sp. 

differ from Flexaria sp. of the Horse~hoe Shale 

Member in having the surface of the shell ornamented by concentric bands each bearing a row of 

elongate spine basec, instead of fairly continuous 

costae and costellae. 

This species differs from Juresania nebrascensis 
D46 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

(Owen) in its slightly narrower shape, in having 

well-defined concentric bands in both valves, a short 

delicate breviseptum in the brachial valve, and 

narrow lobate adductor muscle-scar platforms instead of a markedly dendritic posterior pair of adductor muscle scars and short rounded raised platforms supporting the anterior pair of muscle scars. 

The Amsden species differs from J. symmetrica (McChesney) in its smaller size, narrower shape, 

stronger concentric ribbing, more elongate spine 

bases, and fewer spines. Differences from J. ovalis 

Dunbar and Condra are apprmdmately the same, 

except that the shape of the shell is more similar. 

The Amsden shells probably belong in a new 

species, but the material at hand is not considered 

sufficient for erection of a new name. 

Figured specimens.-USNM 163771, 163772. 

Mentioned specimen.-USNM 163773. 

Occun·ence and nu,mber of speci1nens.-Horseshoe 

Shale Member, collection 54 (1), Johnson County. 

Ranchester Limestone Member: collections 52 (2), 

Johnson County; 100 ( 1), Lincoln County; 134 ( 1) , 

Sublette County; 141 (1), 142 (1), Teton County. 

Family DICTYOCLOSTIDAE Stehli 

Genus ANTIQUATONIA Miloradovich, 1945 

Antiquatonia blackwelderi n. sp. 

Plate 5, figures 10-19 

Diagnosis.-Moderately large, shallowly sulcate 

dictyoclostid having slight geniculation over middle 

of pedicle valve and strong geniculation at edge of 

visceral disc in brachial valve. Posterior slope 

strongly reticulate; costae on anterior part of valve 

fairly regular. Adductor muscle-scar platforms in 

brachial valve massive, depressed medially, and inclined posteriorly. 

Description.-Shell moderately large; pedicle 

valve transversely suboval to subtrapezoidal in outline; ears large so that some shells are widest at 

hinge. In side view valve appears well rounded, 

greatest convexity occurring in umbonal region, 

gradually lessening anteriorly exception over middle 

of visceral disc where slightly increase in convexity 

occurs; trail gently convex to flat. In posterior view, 

valve appears highly arched, generally indented 

medially by moderately deep to shallow sulcus beginning 10 to 20 mm in front of beak; lateral slopes 

steeply inclined; umbonal slopes also steep, diverging at angle normally of 110°. Umbonal region set 

off from moderately arched ears by diverging sulci 

at base of umbonal slopes. On slope within or just 

above each lateral sulcus is curved diagonal spinebearing ridge. Beak protruding slightly beyond 

hinge. 

Surface sculpture of pedicle valve consisting of 

costae, rugae, and spines. Costae beginning at umbo 

and extending to anterior margin, increasing by 

bifurcation, are rounded and separated by subequal 

rounded intercostal grooves, four or five occurring 

in space of 5 mm on anterior slope. Rugae on posterior one-third of valve are slightly wider but usually 

slightly weaker than costae; fine concentric growth 

lines also present. Moderately erect hollow spines 

scattered over shell; on anterior slope, spine bases 

are wider than costae and spaced 8 to 13 mm 

apart. Row of five or six spines follows along top 

of diagonal ridge on each flank above ears, spines 

increasing in size anteriorly; row curving downward 

just beyond end of ridge. Row of seven smaller 

spines present along posterior margin at angle of 

20° to hinge; spines in both rows directed posteriorly and slightly downward. Spine row on each 

flank at angle of 45° to hinge. 

Interior of pedicle valve having slightly raised 

adductor muscle-scar platform beginning about 12 

mm in front of umbo and extending forward 12 

to 15 mm; reaching 8 mm in width, platform 

narrows and tapers off at anterior end. At either 

side of platform, pair of indistinct subtriangular 

longitudinal grooved diductor muscle scars, roughly 

15 mm long and 15 mm wide, fans out anteriorly; 

anterior part of trail studded within with fine 

closely spaced endospines. 

Brachial valve flat posteriorly and gently concave anteriorly, but medially gentle fold, corresponding to medial sulcus of pedicle valve, continues on to trail. Each cardinal extremity set off 

by short diagonal ridge; along margin of visceral 

disc valve appearing rounded, almost geniculate; 

trai~l approximately straight. Ornamentation in brachial valve consisting of costae, rugae, and growth 

lines, similar to those on pedicle valve, but no spines 

present. 

Interior of brachial valve having pair of sharp 

cardinal ridges, curving slightly backward toward 

cardinal process; other end terminating rather 

abruptly at cardinal extremities. Cardinal process 

of linoproductid type, appearing massive on top, 

almost sessile; myophore triangular, approximately 

vertical, trifid, having double-ridged middle lobe, 

lobes converging downward. Posterior platform of 

moderate width, subtriangular in cross section, 

terminating above in low median septum that extends forward from cardinal process. Adductor 

muscle-scar platforms massive, outer edge formed 

by two thick raised ridges, highest just in front of 

middle, inclined posteriorly, merging with poste-
BRACHIOPODA OF THE AMSDEN FORMATION D47 

rior platform and terminating anteriorly in two 

narrow low subtriangular lobes. Posterior pair of 

adductor muscle scars crudely dendritic, occupying 

depressions within and at rear of muscle-scar platforms ; anterior pair smaller and fairly smooth. 

Emerging from between muscle-scar platforms, 

median septum is higher, bladelike, crossing visceral disc almost to anterior edge. Brachial ridges 

extending from just in front of middle of adductor 

muscle-scar platforms outward, beginning at angle 

of 80° to median septum, curving forward, then 

along edge of visceral disc, and finally recurving 

toward muscle-scar platform. Fine endospines 

marking anterior part of trail. 

Dimensions.-Although none of our specimens is 

suitable for accurate measurement, an averagesize specimen, 40 mm long, has a maximum width 

of roughly 46 to 48 mm and depth of approximately 

25 mm. 

Discussion.-This species is named in honor of 

Eliot Blackwelder, whose pioneering work on the 

geology of western Wyoming contributed greatly 

to the knowledge of this region and who collected 

some of the specimens studied. The description 

above is based on specimens collected by Blackwelder in the Gros Ventre Range, supplemented by 

material from Hoback Canyon which has added 

information on the internal characters of both 

valves. All the occurrences of A. blackwelderi in the 

Amsden Formation are in beds of Morrowan equivalence, as indicated by other megafossils and by 

microfossils. 

Comparisons and affin'ities.-Antiquatonia blackwelderi is distinguished from A. coloradoensis by 

its somewhat larger shell having wider and more 

prominent ears, generally coarser costation, and by 

its wider and longer but generally less elevated adductor muscle-scar platform in the pedicle valve. 

A. blackwelderi appears closest to A. hermosana 

( Girty), but the Colorado species is more evenly 

convex, both in side and posterior profile, lacks the 

tendency toward geniculation in the pedicle valve 

and rather strong geniculation at the edge of the 

visceral disk in the brachial valve of A. blackwelderri. 

A. hermosana also has slightly coarser and less 

regular costae that tend to bifurcate freely on the 

anterior and anterolateral slopes, increasing the 

number of costae a little faster than available space 

can accommodate them, so that a rude bunching or 

fasciculation of the costae commonly occurs. The 

internal characters of A. hermosana are as yet 

poorly known. 

Types.-Holotype, USNM 16377 4; para types, 

USNM 163775-163780 (10 paratypes). 

Ocurrence and number of specimens.-Ranchester Limestone Member: collections 83 (4), 84 (2), 

100 (3), Lincoln County; 130 (4), 131 (12), 136 

(1), 139 (5), 141 (1), 143 (fragment), Teton 

County; 133 (3), 134 (8), Sublette County. 

Antiquatonia cf. A. coloradoensis ( Girty) 

Plate 5, figures 1-9 

Productus inflatus McChesney. Girty, 1903, p. 359-361, pl. 3, 

figs. 1-3. 

Productus in flatus? Girty, 1904, pl. 11, figs. 5, 6; Boutwell, 

1912, pl. 6, figs. 3-4. 

Productus inflatus var. colorado,ensis Girty, 1910, p. 215; 

1920, pl. 55, figs. 3, 4. 

Productus coloradoensis Girty. Girty, 1927, pl. 27, fig. 17; 

1935, p. 7-9, pl. 2, figs. 1-4. 

Dictyoclostus colora,doensis ( Girty). Sutton, 1938, p. 563. 

Antiquatonia coloradoensis (Girty). Stehli, 1954, p. 317; 

Muir-Wood and Cooper, 1960, p. 272; Hoare, 1961, p. 

57-59, pl. 7' figs. 6-9; s~tevens, 1962, pl. 95, figs. 2, 3, 5. 

"Dictyoclostus" inflatus (McChesney). Easton, 1962 [part], 

p. 52-54 (locs. 13382-PC, 13403-PC, 13404-PC, 13421-

PC, 13423-PC). 

Antiquatonia peTnodosa Easton, 1962 [part], p. 58, 59 [not 

pl. 7, figs. 6-8] (locs. 13421-PC, 14220-PC). 

"Buxtonia" aTizonensis Hernon. Easton, 1962 [part], p. 62 

[not pl. 8, figs. 5, 6] (locs. 13404-PC, 13421-PC). 

Lectotype of Productus coloradoensis Girty.-

Some confusion has resulted from the fact that 

Girty described this Pennsylvanian species in a 

paper on the Late Mississippian fauna of the Fayetteville Shale of Arkansas (Girty, 1910, p. 215, 

216) as a variety of Productus in/latus McChesney. 

This has caused some authors to cite Mississippian 

shells under this name. Girty stated clearly, however, that he was erecting the name coloradoensis 

for the western shells he had described and figured 

as P. in/latus in his Colorado report (Girty, 1903, 

p. 359-361, pl. 3, figs. 1-3). Three specimens from 

one locality were used in illustrating this species; 

these are syntypes of P. coloradoensis. 

The desirability of selecting a lectoype from these 

specimens has been called to my attention by J. L. 

Carter. I therefore designate the specimen illustrated by Girty (1903) on his plate 3, figures 1 to 

1b, as the lectotype. This specimen is USNM 35345 

in the type collection of U.S. National Museum and 

measures (in mm) : length 36.5, length along arch 

69, maximum width 41, and convexity 24.5. Figured 

paralectotypes are the specimens illustrated on the 

same plate in figures 2, 2a (USNM 121482) and 3 

(USNM 121483). Unfigured paralectotypes include 
D48 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

11 specimens numbered USNM 8258 and 5 specimens numbered USNM 11660, all from the same 

locality as the figured primary types. 

The type locality for Antiquatonia coloradoensis 

(Girty) is USGS locality 2281 (old register-specimens marked by green paper tabs) . Published and 

hitherto unpublished data place this locality on the 

crest of the ridge south of Four Mile (Horseshoe) 

Creek, about 2 miles east of Horseshoe Mountain and 

8 miles west-southwest of Fairplay, Colo. (This locality would be approximately in the NE1;4 sec. 18 

(unsurveyed), T. 10 S., R. 78 W., Park County, 

Colo., at an altitude slightly higher than 12,400 

feet.) The collection was made from Weber Shale?, 

bed 38 (or 39) of measured section 18 (Peale, 1874, 

p. 229) . The collector was A. C. Peale in July 1873. 

Bed 38 was described as a unit of limestone and 

bluish argillaceous shale with sandstone, 57 feet 

thick. The productoids were reported to come from 

its upper part. Bed 39 consisted of 34 feet of black 

shaly limestone. The precise locality of the collection 

needs verification. 

Wyoming material.-Shells from two Pennsylvanian localities (three collections) in the northern 

part of the Bighorn Mountains and three in the 

Rawlins hills are included in this category. The 

Wyoming specimens are, for the most part, poorly 

preserved and worn, and many are distorted. The 

characters of the Wyoming specimens include an 

inflated pedicle valve, having small to moderatesized ears and a rather evenly decreasing curvature 

in side profile. The sculpture consists of costae and 

costellae, of which six to eight occur in the space of 

5 mm on the middle of the visceral disc and five or 

six, rarely seven, in 5 mm along the anterior 

margin. These characters are roughly those of A. 

coloradoensis. In contrast to Girty's Colorado species, all the primary types of which have a shallow 

median sulcus in the pedicle valve, most of the 

Wyoming specimens are without a sulcus. 

The shell illustrated on plate 5, figures 6-9, is 

the most complete and best preserved of our specimens, but it is a pathologic individual, showing 

damage in the form of a longitudinal trough in 

the middle of the brachial valve which appears as 

a ridge on the anterior slope of the pedicle valve. 

The finely reticulate posterior part of the pedicle 

valve is well shown in this shell, which has the 

following dimensions (in mm) : length 27, length 

along arch 52,. greatest width 36, width at hinge 

(twice the half width) 29 ?, and convexity 18. 

An internal mold in chert (pl. 5, fig. 4) shows 

the adductor muscle-scar platform on the interior 

of the pedicle valve. This begins about 10 mm in 

front of the umbo and is 9 mm long; it averages 

3 mm wide throughout most of its length but is 51j2 

mm wide at its anterior end. Both the adductor and 

diductor muscle scars are not clearly defined on 

this specimen. 

Internal characters of the posterior part of the 

brachial valve are shown on a fragment from a 

limestone bed of Atokan age in the Rawlins hills 

(pl. 5, fig. 5). The cardinal process is massive, trifid 

posteriorly, and almost sessile against the thick 

elevated cardinal ridges; these ridges are inclined 

posteriorly and extend strongly almost to the cardinal extremities, near each of which a short diagonal 

ridge splits off. The median septum is shallow and 

indistinct over the posterior platform but extends 

forward past midlength from between the pair of 

medium-sized adductor muscle-scar platforms, 

which are subtriangular and somewhat elevated 

anterolaterally. The middle of the valve adjacent to 

the muscle-scar platform is irregularly pitted. 

Discussion.-Similar shells occur in the Tyler 

Formation and Alaska Bench Limestone in central 

Montana. These include specimens identified by 

Easton (1962, p. 53, 59, 62) as "Dictyoclostus" inflatu,s (McChesney), the type of species of Inflatia 

Muir-Wood & Cooper ; A ntiquntonia pernodosa Easton; and "Buxtonia" arizonensis Hernon. The Montana collections in which these occur are listed in 

the synonymy. Some of these specimens also lack a 

median sulcus. Our reevaluation of the Carboniferous faunas of central Montana indicates that 

neither lnflatia nor any genus of buxtonids is presently known in the Tyler Formation and Alaska 

Bench Limestone. 

The antiquatonias of the Amsden of Wyoming 

and Montana may belong in a subspecies of A. 

coloradoensis that differs from the typical form in 

generally lacking a sulcus in the pedicle valve. Such 

a decision, however, cannot be based on the poorly 

preserved Wyoming material and the sparse and 

rather incomplete Montana material. 

Restudy of the Montana material has shown also 

that Antiquatonia pernodosa Easton is a somewhat 

smaller species than A. coloradoensis and is restricted to the Big Snowy Group of Late Mississippian age. The sulcus is prominent in this species, the 

sculpture slightly coarser than in typical A. coloradoensis, and the spine pattern is different. As is 

typical in Mississippian antiquatonias, the row of 

spines above the notch on each flank is fairly 

straight and appears continuous with a row of 

moderately large spines that crosses the middle of 
BRACHIOPODA OF THE AMSDEN FORMATION D49 

the anterior slope. This character is also present in 

A. antiquatus (Phillips), the type of species of Antiquatonia. In the Pennsylvanian forms, by contrast, 

the spines in a row above the notch increase rapidly 

in size, and the row curves around the ear and tends 

to follow the direction of the costae. This is the pattern found in A. coloradoensis. 

Types.-Lectotype, USNM 35345; paralectotypes, 

USNM 8258, 11660, 121482, 121483. 

Figured specimens.-USNM 163782-163785. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 5 ( 1), Carbon County; 

53 (1), Johnson County. Ranchester Limestone 

Member: collections 6 (45), 13 (5), 15 (7), Carbon 

County; 67 (1) 68 (1), Sheridan County. 

Antiquatonia sp. 

Fragments of medium-sized pedicle valves from 

limestone beds in the Covey Cutoff section and at 

Soda Creek are referred to Antiquatonia on the 

basis of shape., costation, and what can be seen of 

the spine arrangement. This Mississippian material 

is too poor for one to determine whether or not they 

belong in Antiquatonia pernodosa Easton or some 

other species. The Late Mississippian antiquatonias 

in the Unjted States have not been adequately 

studied and described. In the Great Basin of Nevada 

and Utah (the Mississippian productoids of which 

are under study by the writer), Antiquatonia is locally abundant, ranging upward from beds of late 

Meramecian age. 

Mentioned specimens.-USNM 163787. 

Occurrence and number of specimens.-Moffat 

Trail Limestone Member: collection 93 (3), Lincoln County. Horseshoe Shale Member : collection 

?41 (1), Teton County. 

Fa·mily LINOPRODUCTIDAE Stebli 

Genus OVATIA Muir-Wood and Cooper, 1960 

Ovatia croneisi (C. Branson) 

Plate 6, figures 1-6 

Linoproduc,tus croneisi C. Branson, 1937, p. 656, pl. 89, figs. 

13-15; Sutton, 1938, p. 558; ?Easton, 1962 [part], 

p. 510, 51, pL 6, fig. 9. 

Cancrinella boonensis (Swallow). Burk, 1954, p. 10, pl. 1, 

fig. 35. 

Ovatia croneisi (G. Branson). Muir-Wood and Cooper, 1960, 

p. 298. 

Diagnosis.-Moderately large, broadly arched 

linoproductid having rather low umbonal region and 

shallow visceral cavity. Both valves ornamented by 

30 to 36 capillae in space of 1 em; pedicle valve with 

double spine row along hinge. 

Description.-Pedicle valve transversely oval in 

outline, greatest width occurring a little in front 

of hinge (cardinal extremities broken off in described adult specimen). Convex in side profile, 

curvature decreasing gradually from umbo forward. 

In posterior profile broadly arched over visceral 

disc, flanks sloping, gently convex. Umbonal region 

depressed to moderately convex; umbonal slopes 

gently convex, sloping, poorly delimited, diverging 

roughly at right angle from umbo, lower part of 

slopes concave, rounding gradually into ears, forming broad diagonal sulci. Beak protrudes very 

slightly across hinge line. 

Ornamentation of pedicle valve consisting of fine, 

slightly flexuous capillae, narrowly rounded and 

separated by slightly narrower to slightly wider 

grooves; capillae increasing by intercalation. A few 

weak rugae present over posterior part of visceral 

disc, strongest on sides and near hinge, and 

strengthening slightly towards cardinal extremities, 

but not becoming markedly stepped. Fine, almost 

microscopic growth lines also present. Spines small, 

occurring ( 1) in double row along hinge, two or 

three also scattered just in front of this double 

row, at either side of diagonal sulci, and (2) as 

smal~l anteriorly inclined spine bases scattered over 

slopes 4 to 6 mm apart. 

Brachial valve concave, having a little less curvature than pedicle valve. Visceral cavity reaching 

maximum height of about 4 mm. Ornamented by 

fine bifurcating capillae similar in strength and 

spacing to those of pedicle valve; weak concentric 

grooves over visceral disc. Spine base·s not observed. 

Internal characters of brachial valve not known. 

Dimensions of specimen UW A1281 (in mm) 

are as follows: Length 30.5, length along arch 45, 

maximum width 40, and depth 27.5. Specimen is 

not complete but is the largest available. 

Discussion.-Branson described this species from 

immature and fragmental specimens weathered out 

at Cherry Creek. The holotype, 10 mm long by 

10.5 mm wide, (pl. 6, figs. 4-6) the paratypes, and 

subsequently collected topotypes all have low convexity and a very shallow visceral cavity. The most 

complete specimen to come to light, a topotype 

preserved in sandstone in the University of Wyoming collection, has been the main source of the adult 

characters in the foregoing description and is illustrated on plate 6, figures 1-3. Although this specimen is somewhat more inflated posteriorly than 

the shells preserved in shale, the spacing and 

strength of the capillae and the details of the spine 

bases indicate that the same species is represented. 

The relatively low convexity of the posterior part 

of the shell, the very shallow visceral cavity, and 

the capillate ornamentation and rather sparsely 
D50 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

scattered small spines are the distinguishing characters of this species. 

Specimens from central Montana identified by 

Easton as Linoproductus croneisi Branson probably do not belong in 0. croneisi, with the possible exception of the one figured by Easton (1962, 

pl. 6, fig. 9), and even it should be questioned. All 

are more convex than typical 0. croneisi. The species 

from the Cameron Creek (USGS colin. 13382-PC), 

represented by five s~pecimens, is a small rather deeply convex highly spinose form having prominent 

rugae and very low capillae; it certainly should not 

be assigned to 0. C'roneisi. One specimen from the 

Heath Shale (USGS colin. 13360-PC) is incomplete 

and could be a variant of 0. duodenwria (Easton) 

with slightly finer costellae than is normal for that 

species. 

0. croneisi has been identified at Cherry Creek 

and South Pass in the Wind River Range. Crushed 

specimens from Berry Creek in the Teton Range 

are referred with question to this species. 

Types.-Holotype and para types, UM 6831; hypotype UW A1281. 

Occztrrence and nurnber of specimens.-Horseshoe 

Shale Member: collections 22 (3), 26b (1), 27 (1), 

31 (1), ?34 (1), 36d (8), Fremont County; ?149 

(2), ?152 (2), ?155 (1), Teton County. 

Ovatia muralis n. sp. 

Plate 6, figures 7-17 

Linoproductus prattenianus (Norwood and Pratten). Burk, 

1954, p. 9, 10, pl. 1, figs. 36, 37. 

Diagnosis.-Small- to medium-sized linoproductid, 

length approximately equal to width, having rather 

elevated umbonal region; cardinal extremities approximately rectangular; flanks almost vertical. Longitudinal ornamentation of 20 to 25 costellae in 

space of 1 em on anterior slope. Double row of spines 

along hinge, two or three large ones near cardinal 

extremities. 

Descr·iption.-Shell of moderate size; pedicle valve 

subquadrate to subpentagonal in outline, length approximately equal to width; greatest width occurring at or slightly anterior to middle of shell; cardinal extremities forming angles that approximate 

goo. In side profile, curvature decreasing gradually 

from umbo, cut convex to anterior margin. In posterior profile, strongly convex over visceral disc; 

flanks approximately vertical dorsad of plane extending concentrically forward from ears, merging 

gradually with anterior slope. Umbonal region elevated, its slopes convex, steep, diverging anteriorly 

at angles of 85°-90°, rounding rather strongly toward ears forming diagonal sulci along base of urnbonal slopes. Beak protrudes slightly across hinge 

line. 

Interior of pedicle valve poorly known; adductor 

muscle-scar platform indistinct. Diductor muscle 

scars longitudinally grooved, set in shallow suboval depressions roughly 7 mm long and 10 mm 

wide, beginning about 12 mm in front of umbo in 

mature specimen. 

Ornamentation on pedicle valve of straight to 

slightly flexuous narrowly rounded costellae, increasing by intercalation, separated by narrow intercostal grooves; on early parts of shell, within 

10 mm of umbo, 12 to 14 costellae occur in space 

of 5 mm; on mature parts of shell 10 to 12 costellae 

occur normally in space of 5 mm. Concentric wrinkles present on umbonal slopes and ears, rather 

steplike in appearance toward cardinal extremities; at outermost of these, shell bends abruptly 

into nearly vertical flanks. Spines occurring (1) in 

double row of fine spine bases along hinge, two or 

three large spines occurring at cardinal extremities, 

(2) elliptical spine bases scattered sparingly over 

valve, reaching 2 mm in length by 1 mm in width 

on anterior slope. 

Brachial valve rather deeply concave; visceral 

cavity reaches height of as much as 9 mm in adult 

shells. Details not preserved. 

Dimensions ( 1:n mm) of four pedicle valves are as 

follows.-

USNM USNM USNM USNM 1 163791 2 163795 1 163792 1163793 

Length ---------- 3 34 19.5 9.2 5.9 

Length along arch _ 35 15 9 

Maximum width -- 35 21 8.2 6.2 

Width of hinge -- 30.5 19 6 4 6 

Depth ----------- 24 13 5.5 4 

1 USNM 163791-163793 are from collection 93. ~ USNM 163795 is from collection 45. 3 Estimated. + Twice the half width. 

Discussion.-This description is based on specimens from the Covey Cutoff section, two of which 

are figured (pl. 6, figs. 7-10, 15-17). They occur 

in association with Diaphragmus cestriensis 

(Worthen) at that locality and at Hoback Canyon. 

The distinguishing characters of 0. muralis are 

its moderate-sized shell of subequal length and 

width, its strongly convex umbonal region, the 

spacing of the costellae 10 to 12 in 5 mm, the prominent longitudinal elliptical spine bases and, most 

important, the subquadrate ears that recurve abruptly into the nearly vertical flanks. 

The figured specimen from Livingston Ranch 

(pl. 6, figs. 11-14), differs from those from the 

type locality only in being somewhat flatter over 

the visceral disc, but this slight depre,ssion of the 
BRACHIOPODA OF THE AMSDEN FORMATION D51 

central part of the valve might have taken place 

after burial. Two specimens from Horse Creek, 

referred to this species with some question because 

of rather poor preservation, were figured by Burk 

(1954, pl. 1, figs. 36, 37) as Linoproductus p/rattenianus (Norwood and Pratten). 

This species differs from 0. croneisi in having a 

more elevated and convex umbonal region, slightly 

coarser costation, larger and more prominent spine 

bases, and very steep, rather straight flanks. Immature specimens of 0. muralis, consisting of little 

more than the beak and part of the visceral cavity, 

can be distinguished easily from similar specimens 

of 0. croneisi, which has very low convexity initially 

and a visceral cavity of exceedingly limited height. 

0. duodenaria (Easton) has a smaller shell, forming a lower arch over the visceral disc, having a 

narrower hinge, and lacking the steep vertical flanks 

of 0. muralis. 

Types.-Holotype, USNM 163791; paratypes) 

USNM 163792-163795. 

Occurrence and number of specimens.-Moffat 

Trail Limestone Member: collections 93 (12), Lincoln County; 121 (1), 122 (1), Teton County. 

Horseshoe Shale Member: collections ?43 (2), 45 

(1), Fremont County. 

Genus LINOPRODUCTUS Chao, 1927 

Linoproductus eastoni n. sp. 

Plate 6, figures 18-31 

Linoproductus nodosus (Newberry), n. subsp. Easton, 196·2 

[part], p. 50, pl. 6, figs. 6-8b. 

Diagnosis.-Moderate-sized L'inoproductus having large umbo and extended flaring trail ornamented by 18 to 28 costellae and capillae in space of 

1 em; single row of spines along hinge in pedicle 

valve at 10° angle to hinge; coarse spines scattered 

over anterior slope. Brachial valve deeply concave 

over viscera,} disk. 

Description.-Pedicle valve elongate-oval in outline, widening anteriorly, greatest width near or 

somewhat anterior to middle. Curvature in side profile decreasing gradually but slightly unevenly from 

umbo, remaining convex over viscer,al disc; trail 

somewhat variable in curvature, gently convex to 

straight, locally concave. Posterior profile subtrapezoidal, gently convex medially over visceral disc, 

rounding more strongly at either side into inclined 

flanks, which are gently convex to straight. Urnbona! region elevated, prominent, rather elongate; 

umbo incurved over hinge ; umbonal slopes steep, 

rounding rather abruptly into ears; apical angle 

110°, umbonal slopes diverging, a little further 

forward, at approximately 85°. Hinge fairly short 

on most shells with more extended hinge, cardinal 

extremities are rectangular to subacute. Trail flaring anteriorly, on some specimens forming weak fold 

near anterior margin (pl. 6, fig. 30). Interior of 

pedicle valve not known. 

Ornamentation of pedicle valve consisting of 

rounded costellae, somewhat flexuous and increasing by intercalation, separated by subequal rounded 

intercostal grooves; typically 9 to 11 costellae occur 

in space of 5 mm. Coarse wrinkles present on urnbona! slopes and flanks, strengthening toward ears; 

not crossing ventral part of valve. Spines (1) occurring in a row of four or five prominent spine bases 

increasing in size toward ears and diverging at angle 

of 10° to hinge line at either side of umbo, (2) of 

two types scattered over anterior part of visceral 

disc and on trail, large erect spines arising from 

spine bases as much as 3 mm long and 1.5 mm wide, 

bearing spines as much as 1.5 mm in diameter near 

base, concentrated in middle part of anterior slope 

( costellae converging and tending to merge in front 

of large spine bases), and smaller anteriorly inclined 

spines emerging from individual costellae, more 

common toward flanks. 

Brachial valve deeply concave, rounding into long 

trail ; visceral disc transversely oval, rarely subcircular, steepening rapidly at sides where steplike 

wrinkles correspond to those in pedicle valve. Ornamentation of brachial valve of bifurcating costellae, 

similar in strength and spacing to those on pedicle 

valve. Spines were not observed. 

Interior of brachial valve having strongly convex visceral disc ; posterior platform broadly 

rounded, merging with convex valve floor, supporting short sessile cardinal process; myophore bilobate above and trilobate posteriorly, having broad 

deeply sulcate median lobe giving myophore quadrilobate appearance; shallow alveolus present on 

some specimens. Cardinal ridges emanating from 

base of cardinal process and dive·rging at angle of 

20° to hinge line, dying out on floor of valve about 

halfway toward cardinal extremities. Median septum 

bladelike, merging with anterior part of posterior 

platform and extending roughly two-thirds of way 

forward across visceral disc. Adductor muscle scars 

indistinct, weakly dendritic where visible, set on 

slightly thickened subtriangular areas at either side 

of median septum. 
D52 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Dimensions (in mm) .-

Pedicle valveR Brachial valves 

USNM USNM USNM USNM USNM 1163797 2 163801 ] 163796 1163798 3 163800 

Length ---------- 4 33 ;, 30 46 39 31.5 

Length along arch 4 74 "46 68 60 51 

Maximum width - 46 31 45 44 31 

Width of hinge __ 34 33 35 20 

Maximum width of 

visceral disk ___ 25 31 29 19 

Depth ___________ 4 28 16 22 18 16 1 Primary types USNM 163796-163798 are from USGS collection 16177-PC. 2 Primary type USNM 163800 is from collection 54. 3 Primary type USNM 163801 is from collection 53. ~ Trail incomplete and distorted by compression. 5 Trail incomplete but undistorted. 

Discussion.-The species is based primarily on 

specimens from the Big Snowy Mountains in central 

Montana. It also is fairly common in the Ranchester Limestone Member at various localities in Wyoming; two para types from the Bighorn Mountains 

are illustrated (pl. 6, figs. 18, 22, 23, 27, 28). The 

Bighorn Mountains specimens are a little smaller 

and more finely costate than those from Montana, 

some having locally as many as 28 costellae and 

capillae in a space of 1 em, but otherwise have all 

the distinguishing characters of typical L. eastoni. 

The same species was described by Easton (1962, 

p. 50) under the name "Linoprod1wtus nodosus 

(Newberry), n. subsp." Most, if not all, of Easton's 

specimens from the Cameron Creek Formation and 

Alaska Bench Limestone belong in L. eastoni, but 

not those from the Heath Formation which include 

specimens ornamented by capillae as in Ovatia 

croneisi. 

None of the Montana-Wyoming shells belongs in 

Newberry's species. L. nodosus is identified by a 

row of spines along the median plane of the pedicle 

valve. L. eastoni differs from L. nodosus in having 

spines scattered randomly over the surface of the 

pedicle valve, in having a longer trail, and in being 

somewhat flatter over the ventral disc in the pedicle 

valve. The highly convex visceral disc in the interior 

of the brachial valve and long flaring trail, with a 

faint median fold on some pedicle valve, are characters that also serve to distinguish L. eastoni. 

L. eastoni differs from Ovatia croneisi in having 

slightly coarser costation, but the costellae of 0. 

muralis have about the same strength and spacing 

as in some specimens of L. eastoni. The distinctive 

shape of L. eastoni, particularly the subtrapezoidal 

posterior outline and flaring trail distinguish it 

readily from the more evenly arched Mississippian 

ovatias with their relatively short trails. 

Type locality.-The type lot was collected at 

USGS locality 16177-PC in Stonehouse Canyon, 

Golden Valley County, Mont., in 1955, while I was 

there on a field trip with W. H. Easton, L. S. 

Gardner, P. E. Cloud, and R. J. Ross. The linoproductids, in association with Rugosochonetes 

pseudoliratus (Easton) and Antiquatonia "pernodosa" Easton, came from 1 foot of buff-gray calcareous siltstone near the middle of unit 22 of 

Easton's published section (Easton, 1962, p. 122) at 

that locality, which is in the SE1,4NW1;4 sec. 31, T. 

11 N., R. 21 E. This unit was assigned to the Alaska 

Bench Limestone in the published sections but cited 

as Cameron Creek Formation in the paleontological 

part of the report. In the field, Easton placed the 

collection 3 feet below the base of the Alaska Bench 

Limestone. Maughan and Roberts (1967, pl. 4) 

also placed the collection in the Cameron Creek. 

From a total of 20 specimens of L. eastoni in this 

collection, the holotype and ejght paratypes have 

been selected. 

Occu1·rence and number of Wyoming specimens.-

Horseshoe Shale Member : collections 1 ( 4) , Carbon County; 53 ( 35), 54 ( 5), Johnson County. 

Ranchester Limestone Member: collections ?84 ( 1) , 

?100 (1), Lincoln County; ?130 (1), ?131 (1), 136 

(14), 141 (1), Teton County; 133 (2), 134 (8), 

Sublette County. 

Linoproductus planiventralis Hoare 

Plate 5, figures 20-25 

Linoproductus planiventralis Hoare, 1960, p. 228, pl. 32, figs. 

1-3; 1961, p. 66, 67, pl. 7, figs. 16, 17, pl. 8, figs. 7-9; 

Sturgeon and Hoare, 1968, p. 50, pl. 16, figs. 22, 23, 

pl. 17, fig. 13. 

Diagnosis.-Medium-sized Linoproductus having 

small umbo and fairly long trail, ornamented by 10 

to 16 costae and costellae in space of 1 em ; two 

nearly parallel spine rows along hinge, equal in 

prominence; spines few over anterior slope. Brachial valve shallowly concave over visceral disc. 

Description.-Pedicle valve subquadrate in outline, greatest width at or slightly anterior to hinge; 

curvature in side profile decreasing fairly rapidly 

from umbo; trail gently convex to straight. In 

posterior profile, valve rather low arched over visceral disc, becoming even more depressed over its 

anterior margin; flanks moderately steep, nearly 

straight. Ears moderately large, gently arched. Urnbona! region fairly short, beak incurved; umbonal 

slopes inclined, rounding gradually into ears, diverging at angle of about 105° at umbo. 

Pedicle valve ornamented by rounded costae and 

some costellae, increasing by intercalation, separated by rounded grooves whose width approximates that of costae. Wrinkles present on umbonal 
BRACHIOPODA OF ·THE AMSDEN FORMATION D53 

slopes and flanks near ears, typical of Linoproductus. Spines occur in double row along hinge, increasingly gradually in size toward cardinal extremities, and a few large spines scattered over shell, 

generally in median part ; spine bases reaching 2.5 

mm in length 1.5 mm in width and some spines 

slightly exceeding 1 mm in diameter near base; 

costae tend to converge anterior to spine bases. 

Interior of pedicle valve poorly known. Adductor 

muscle-scar area indistinct, narrow, beginning 

about 7 mm in front of umbo. Diductor musclescar areas at either side, rather strongly ridged 

longitudinally, occupying areas 7-15 mm in front 

of umbo. 

Brachial valve moderately deep but shallowly 

concave over visceral disc, generally showing faint 

broad fold near anterior edge of visceral disc; 

ears bordered anteriorly by slightly diagonal ridges. 

Faint wrinkles and rugae present, strongest at side 

and near ears. Ornamentation of bifurcating costae 

and costellae equal in strength and spacing to those 

on pedicle valve. 

Interior of brachia~l va'lve with short cardinal 

process, bilobate above; details of myophore not 

seen. Cardinal ridges fairly straight, paralleling 

hinge lines, then curving forward short distance, 

separating visceral disc from ears, and dying out. 

Median septum continuing forward from cardinal 

process, weakly differentiated from convex posterior platform. Other details not preserved. 

Most complete pedicle valve (USNM 167715) has 

following dimensions (in mm) : length 33, length 

along arch 57, maximum width 40 (twice the half 

width), depth 17. Brachial valve (USNM 167717) 

measures: length 26, length along arch 28, maximum width 33, width of hinge 32 (twice the half 

width) , depth 7. 

Discussion.-This species was originally described 

by Hoare (1960, p. 228; 1961, p. 66) from the Seville Limestone of Des Moinesian age in southwest 

Missouri. More recently Sturgeon and Hoare (1968, 

p. 50) have recognized it as the common Linoproductus in the Pottsville Group in Ohio. Specimens 

from the Amsden Formation from beds of later 

Morrowan and early Atokan age in the Rawlins 

hills, from which the foregoing description was 

made, agreed rather closely with the Pottsville examples and fall well within the limits of this species 

as described by Sturgeon and Hoare. 

Linoproductus planiventralis is clearly distinct 

from L. eastoni n. sp. differing in its subquadrate 

outline, shorter beak and trail, absence of any 

tendency to form a fold on the trail in the pedicle 

valve, much less concave visceral di,sc in the brachial valve with its broad weak fold developed on 

the anterior part, relatively wider hinge, and the 

presence of costae, rather than costellae, as the 

major element of longiti udinal ornamentation on 

both valves. In L. eastoni the spine row near the 

posterior margin in the pedicle valve diverges at 

an angle of 10° and the cardinal ridges within the 

brachial valve diverge at angles of 20° to the hinge 

line; in L. planiventralis both are parallel to the 

hinge line. Finally, the spines on the slope of the 

pedicle valve in L. planiventralis are not as thick 

nor as numerous as in L. eastoni. 

Figur-ed specimens.-VSNM 167715-167718. 

Occut·r-ence and number- of specimens.-Horseshoe 

Shale Member: collections 2 (3), 3 (19), ?4 (1), 5 

( 1) . Ranchester Limestone Member : collection 6 

(6), Carbon County. 

Order RHYNCHONELLIDA 

Superfamily RHYNCHONELLACEA 

Family not certain 

Genus PUGNOIDES Weller, 1910 

Pugnoides quinqueplecis Easton 

Plate 7, figures 6-30 

Pugnoides ottu1nwa (White). Branson and Greger, 1918, p. 

319, pl. 18, figs. 12-14. 

Selenella? walteri C. Branson, 1937 [part], p. 657, pl. 89, fig. 

22 [not fig. 21]. 

Wellerella osagensis (Swallow). Burk, 1954, p. 14, pl. 1, figs. 

23-25. 

Pugnoides qninqueplecis Eas,ton, 1962, p. 67, pl. 9, figs. 10, 11. 

Diagnosis.-Pugnoides having four or five, rare,ly 

three, rather narrow subrounded to subangular 

plications on fold, separated by shallow grooves. 

Description.-Shell rhynchonelliform, moderately 

small, with prominent fold and sulcus. Both valves 

ornamented anteriorly by 10 to 15 moderately 

shallow plications, 2 to 4 occupying sulcus and 3 to 

5 on fold, obsolete to absent on posterior part of 

shell, crossed by several growth lamellae on anterior 

part of shell; no visible microsculpture. 

Pedicle valve suboval to subpentagonal, rarely 

subtriangular in outline, not very deep, prominently 

rostrate, terminating posteriorly in slightly curved 

umbo. Umbonal slopes converging at angle of 100° 

and flattened so as to form false interarea; umbonal 

s~lopes meeting main part of valve at angulation 

along posterolateral extremities. Interior of pedicle 

valve having pair of moderately short dental plates 

each supporting prominent hinge tooth at either 

side of delthyrial cavity. 

Brachial valve convex, usually deeper than pedicle 

valve, transversely suboval in outline; greatest convexity near middle. Surface slopes steeply to postero-
D54 THE AM8DEN FORMATION (MISSIS.SIPPIAN AND PENNSYLVANIAN) OF WYOMING 

lateral margins and somewhat less steeply to anterolateral margins. Posterior part of valve rather flattened medially; fold restricted to anterior pavt of 

valve, rather elevated at anterior margin. 

Interior of brachial valve having shallow median 

septum occupying posterior two-fifths of valve and 

dividing in two posteriorly to form septalium, each 

side of which ends against one of two crur~l bases. 

Crura moderately long, diverging slightly anteriorly 

and curving toward pedicle valve. Inner hinge 

plates likewise moderately long and perforated by 

an elongate oval hole; outer hinge plates shorter. 

Muscle scars in area of median septum flabellate. 

Dimensions (in mm) .-

1 USNM USNM USNM USNM USNM 167727 167725 167728 167726 167729 

L,ength ____ 13.0 11.5 11.0 10.8 10.5 

Width _____ 12.1 11.1 12.7 10.6 10.6 

Thickness - 7.0 7.1 6.0 6.5 5.5 

Number of 

plicae on 

fold _____ 3 5 5 3 4 1 All specimens from ccllection 38. 

Discussion.-This variable species is rather common in the Composita poposiensis Subzone in central 

and noflth-central Wyoming where it seems to be 

limited to that zone. Specimens are completely replaced by chert except at one collection ( 69) just 

across the border in Montana, which provided silicified shells showing internal structures. 

Two paratypes of Selenella? walte1·i Branson, one 

of which was figured by Branson, probably represent the early neanic stage of this species. Both of 

these tiny shells (UM 6582, 6594) are smooth and 

subtriangular; one of them has the slight depression 

in the midposterior part of the brachial valve typical in rhynchonellids. The holotype of S.? walte1·i 

is more elongate and more rounded anteriorly and 

is not recognized as a rhynchonellid. 

The average specimen of P. quinqueplecis has four 

plicae on the fold, but specimens having three or 

five on the fold are also common. Of 31 specimens 

collected at locality 38, 7, or 22 percent, have 3 

plicae on the fold, 16, or 52 percent, have 4 plicae, 

and 8, or 26 percent, have 5 plicae. This constitutes 

a considerable preponderance (78 percent) of individuals having four or five plicae on the fold. 

P. quinqueplecis is rather closely related to P. 

ottumwa (White) to which species Branson and 

Greger (1918, p. 319) originally referred the Wyoming shells. Specimens of P. ottumwa from the "Pella 

Beds" of Iowa have deeper more angular plicae 

along the anterior margin, and the average number 

on the fold is less. Of 280 specimens from USGS 

locality 5793-PC, about three-fourths of a mile 

south-southwest of Pella, Iowa, 21, or 7¥2 percent, 

have 2 plicae on the fold, 210, or 75 percent, have 3 

plicae, 45, or 16 percent, have 4 plicae, and only 

4, or 11;2 percent, have 5 plicae. By far the most 

(821/:2 percent), have less than four plicae. No 

specimens of P. quinqueplecis have been found having only two plicae on the fold. 

Included in P. quinqueplecis are specimens identified by Burk (1954, p. 14, pl. 1, figs. 23-25) as 

Wellerella osagensis (Swallow) from Cherry Creek, 

South Pass, and Horse Creek. All of them are from 

the Composita poposiensis Subzone and are conspecific with the specimens identified earlier by 

Branson and Greger as Pugnoides ottumwa. Also 

included in P. quinqueplecis are specimens from 

Cherry Creek listed by Shaw and Bell (1955, fig. 1) 

as W ellerella sp. indet. W ellerella osagensis ?, and 

those from Cherry Creek, South Pass, and Horse 

Creek listed by Shaw (1955, p. 62, 63) as Wellerella 

n. sp. A and W ellerella n. sp. B. All these specimens 

have been reexamined by the writer and should be 

referred to Easton's species. 

Figured specimens.-VSNM 167720-167726. 

Additional measured specimens.-VSNM 167727-

167729. 

Occun·ence and nu1nber of specimens.-Horseshoe 

Shale Member: collections ?21 (2}, 26a (5), 26b 

(7), 32 (6), 34 (3), 35 (31), 36a (2), 36b (51), 

36e (10), 38 (34), ?39 (3), 43 (4), B (12), C (14), 

D (2), Fremont County, Wyo.; 69 (100+), Carbon 

County, Mont. Ranchester Limestone Member: collection 82 (1), Lincoln County, Wyo. 

Superfamily STENOSCISMA TACEA 

Family STENOSCISMA TIDAE 

Genus COLEDIUM Grant, 1965 

Coledium fragum n. sp. 

Plate 7, figures 1-5, 32-36 

Diagnosis.-Coledium having fairly narrow subtrigonal shell with narrow fold bearing two closely 

spaced costae; one weak costa in sulcus and as many 

as two on each flank. 

Description.-Shell rather small for genus, subtrigonal in outline, greatest width about two-thirds of 

distance anterior to beak; longer than wide, wider 

than thick, moderately to strongly biconvex; anterior profile commonly subtrapezoidal. Commissure 

uniplicate; fold narrow and moderately high but 

elevated above flanks only at anterior end, crest 

nearly flat; sulcus narrow and fairly shallow, beginning 5 to 7 mm in front of beak, extending forward as tongue into fold; juveniles less than 5 mm 

long have margin straight or slightly indented. No 
BRA~CHIOPODA OF THE AMS-DEN FORMATION D55 

sign of stolidium along anterior margin. Costae 

rather weak, beginning 4 to 6 mm in front of beaks, 

one broad shallow costa in sulcus, on some specimens appearing before sulcus, and generally two 

weak ones at either side; two on fold closely spaced, 

one or two at either side. Valves on mature individuals meeting at anterior margin at angles ranging 

from aeu te to obtuse. 

Pedicle valve strongly convex posteriorly in side 

profile, becoming gently convex anteriorly, moderately convex transversely. Umbo medium sized, urnbona! angle about 105°, beak erect to slightly incurved ridges obtusely subangular on some specimens, subrounded on others; slitlike foramen appears to penetrate apex of beak on best preserved 

specimens. Delthyrium triangular, open, largely 

filled by beak of brachial valve. 

Pedicle valve interior having dental plates forming boat-shaped spondylium sessile on floor of valve 

for slightly less than 1 mm, then elevated on medium 

septum that extends about one-third of way forward 

across valve. 

Brachial valve strongly convex, both longitudinally 

and transversely, less convex over middle part; greatest convexity in longitudinal profile a little posterior 

to middle of valve; beak profile a little posterior to 

middle of valve; beak forming obtuse angle, its 

apex within pedicle valve. 

Dimensions (in mm) .-

USNM USNM USNM USNM 167731 167730 16773.1 167732 

Length ------------- 9.0 6.7 6.2 4.3 

Maximum width ----- 8.8 6.2 6.0 4.0 

Thickness ----------- 5.6 3.9 4.3 2.2 

Discussion.-This species is based on seven fairly 

complete spe-cimens plus a brachial and two pedicle 

valves in a collection from the Moffat Trail Limestone Member. Its distinguishing characters are the 

longer-than-wide subtrigonal shell, the narrow fold 

ornamented by two closely spaced short costae, and 

the fairly weak but distinct costae. 

Coledium obesum (Clark) from the Heath Formation of Montana is more inflated and has a 

broader fold and indistinct costae. C. explanatu,m 

(McChesney) is associated with DiaphTagmus cestriensis (Worthen) at many Chesterian localities in 

the American midcontinent, as is C. fragum in 

this Moffat Trail collection; C. explanatum differs in 

having stronger costae and a somewhat wider fold 

bearing two costae that are separated by an intercostal groove equally as wide as the costae. 

Of the North American coledi urns, the one most 

similar in shape and ornamentation to C. fragum 

is C. rhomboidale (Hall and Clarke) from the Middie Devonian of Indiana. C. rhomboidale differs 

mainly in its costation, having two or three costae 

on the fold and as many as three on each flank; in 

C. f'ragum the number is constantly two on the fold 

and not more than two on each flank. 

Types.-Holotype, USNM 167730 ; paratypes, 

167731-167734 (9 specimens). 

Occurrence and nurnber of specimens.-Moffat 

Trail Limestone Member: collection 93 (10) Lincoln 

County. 

Order SPIRIFERIDA 

Suborder ATHYRIDIDINA 

Superfamily ATHYRIDACEA McCoy 

Family A THYRIDIDAE McCoy 

Genus CLEIOTHYRIDINA Buckman, 1906 

Cleiothyridina atrypoides saginata n. subsp. 

Plate 7, figures 54-57 

Diagnosis.-Cleiothydridina resembling C. at'f'Ypoides Girty, but differing in having more tumid 

shell with subquadrate outline, more strongly convex pedicle valve, and lesser deflection of line of 

commissure by fold and sulcus. 

Descriptions.-Shell moderately small, suborbicular, valves of subequal depth. Pedicle valve atrypiform, tumid, rounded subquadrate in outHne, greatest width very slightly posterior to middle; strongly 

convex in both side and posterior profiles; greatest 

convexity near umbo, gradually decreasing toward 

anterior margin. Umbo low, umbonal slopes diverging at angle of approximately 105°. Sulcus beginning almost imperceptibly near midlength and continuing shallowly and poorly delimited to anterior 

margin where line of commissure e,xhibits broad 

shallow rounded deflection. Delthyrium open, filled 

by beak of brachial valve. 

Brachial valve similar in depth and convexity to 

pedicle valve; greatest convexity in posterior profile at umbo, but in side profile appearing almost 

evenly rounded. Fold poorly delimited, corresponding to sulcus of pedicle valve. 

Surface sculpture on both valves consisting of 

concentric grooves and closely spaced fine lamellae, 

particularly visible and crowded on anterior half 

of shell ; locally fine short spines are visible fringing lamellae. Internal characters of both valves not 

known. 

Dimensions of figured specimen (in mm): length 

15.2, width 15.7, and thickness (both valves) 11.0. 

Discussion.-The unique specimen upon which the 

foregoing description is based was collected in the 

Washakie Range. It differs from previously described North American cleiothyridinas in the great 

convexity of the pedicle valve, which is equal to that 

of the almost hemispherical brachial valve. 
D56 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

This shell is closely allied to C. atrypoides Girty 

from the Fayetteville Shale of Arkansas and Oklahoma, from which it differs in the particulars given 

in the diagnosis. It is regarded as representing a 

western subspecies of C. atTypoides. Its age is 

probably slightly younger than that of Girty's original material of C. atrypoides-middle Chesterian 

as opposed to later early Chesterian. 

C. atrypoides Girty (1910, p. 223) was described 

originally as a variety of C. sublamellosa (Hall), 

from which it differs in having a more convex, deeper pedicle valve and a deeper sulcus that causes a 

marked deflection in the line of commissure. Easton 

(1962, p. 75, pl. 10, figs. 23a-c) selected and designated a "holotype" (lectotype) from among Girty's 

specimens and figured it. He considered C. atrypoides a valid species and assigned to it several 

specimens from the Heath Formation of central 

Montana. Girty's unfigured syntypes of C. atrypoides include several hundred specimens from approximately 20 localities in Arkansas and Oklahoma. 

Easton's designation of the lectotype (USNM 

118718, from USGS loc. 3651C) has fixed the type 

locality of C. atrypoides, which is 6 miles airline 

east of Fayetteville, Ark. 

Holotype.-USNM 168390. 

Occur·rence.-Horseshoe Shale Member: collection 41, Teton County. 

Cleiothyridina hirsuta darwinesis n. subsp. 

Plate 7, figures 31, 38-40, 42-45, 58, 59 

Cleiothyriclina sp. Burk, 1954 [part], p. 13 [not pl. 1, fig. 15]. 

Diagnost:s.-Small CleiothyTidina of moderate 

thickness, subpentagonal in outline, having pedicle 

valve deeper than brachial valve; fold and sulcus 

subdued but fairly broad; umbo rather short, incurved. Interior of both valves having prominent 

coarse radial vascular grooves. 

DescTiption.-Shell atrypiform, subpentagonal, 

tending toward subcircular in outline, lenticular in 

cross section; length subequal to width, being either 

slightly greater or slightly less. Pedicle valve having 

fairly straight posterior margins that diverge at 

angle of approximately 115°, strongly rounded lateral margins that curve less strongly anteriorly, 

and rather straight anterior margin at termination 

of fold and sulcus; greatest width approximately at 

middle of valve; appearing rather evenly ·convex in 

side profile but less convex near anterior margin; 

greatest depth just posterior to middle; evenly 

rounded in posterior profile. Sulcus shallow and 

rather broad, visible only on anterior third of valve. 

Line of commissure broadly and shallowly indented 

anteriorly; in side view, line appears almost straight, 

except at anterior end; viewed from posterior end, 

line of commissure has faint bulge at either side of 

umbo at expense of brachial valve. Umbo fairly small 

and incurved; beak erect; apical angle approximately 

goo. 

Interior of pedicle valve bearing pair of fairly 

short dental plates within umbonal region; interior 

surface marked by straight, rather coarse, relatively 

prominent vascular grooves, 14 on holotype, that 

extend to margin and appear as ridges on internal 

mold. 

Brachial valve similar in outline to pedicle valve 

but shorter and slightly shallower, about four-fifths 

as deep as pedicle valve; greatest depth occurring 

one-quarter to one-third distance from beak to anterior two-fifths of valve; on some, speeimens fold 

bears faint medial longitudinal depression. Surface 

sculpture decorticated in type lot. Interior marked 

by radiating vascular grooves of which 20 occur on 

figured specimen, appearing to increase by intercalation. Shallow sharp short medial groove extending forward from beak; cardinal plate not seen. 

Dimensions (in mm) .-

USNM USNM USNM 1163721 2 168391 2 168392 

Length ---------- 13.2 12.4 

Maximum width __ 12.8 12.6 

Thickness ------- 7.7 7.4 

1 USNM 168391~168393 are from collection 137. ~ USNM Hi3712 is from collection 27. 

~ IT~230 is from collection 43. 

10.5 

10.5 

6.0 

USNM uw 2 168393 a IT-280 

9.6 7.5 

9.3 8.0 

5.5 4.0 

Discussion.-The description above is based on 

six specimens collected by Blackwelder from the 

Darwin Peak section. Several of these are shallowly 

excavated anteriorly at either side of the line of 

commissure, which is marked by a narrow ridge. 

Such an arrangement normally indicates that the 

shell, which is missing from these specimens, was 

fairly thick. That this was so is demonstrated by a 

USGS specimen collected by C. C. Branson at 

Cherry Creek (pl. 7, figs. 58, 59) . This retains 

some of the original shell material and shows the 

closely crowded surface lamellae typical of Cleiothyridina; these, however, lack most of the spines. 

The dimensions of this shell (USNM 163712) are 

given in the table above. Three U.S. National Museum specimens from Amsden Hill, collected by 

C. C. Branson and Hackett are included here, as 

well as two University of Missouri specimens collected by C. C. Branson at Little Popo Agie River. 

Also referred to this species and included in the 

table of dimensions is a small specimen collected by 

C. A. Biggs at Horse Creek, in the collection of the 

University of Wyoming. It was included by Burk 
BRACHIOPODA OF THE AMSDEN FORMATION D57 

(I954, p. I3) among I5 specimens he described as 

Cleiothyridina sp. All except this specimen are young 

compositas, including the one Burk figured. 

Finally, a large silicified specimen collected by I. 

A. Keyte in Enterprise Ditch near Lander is referred to this species with some question. It measures I5 mm long (estimated because the beak is 

missing), I5.5 mm wide, and 8.3 mm thick and is 

figured on plate 7, figures 46-49. Although its shape 

is reasonably close to C. hirsuta darwinensis, the 

surface is relatively smooth, having neither the 

spinose lamellae typical of the exterior of Cleiothyridina nor the vascular grooves typical of the interior of this species, and its sulcus is fairly prominent at the anterior margin. These differences can 

be explained, however, as caused by peculiarities 

of preservation and by its relatively large size and 

therefore fully mature development. 

Comparisons and affinities.-Cleiothydrinia hi,rsuta darwinensis differs from typical C. sublamellosa (Hall), which is somewhat similar in outline, principally in having the pedicle valve as deep 

as or slightly deeper than the brachial, instead of 

having the brachial deeper, as in Hall's species. 

The valves of C. atrypoides Girty are subequal in 

depth, the pedicle, if differing, generally being 

shallower. This fossil is thicker than C. hirsuta 

darwinensis and has a deeper and more prominent 

sulcus. 

C. hirsuta (Hall) also has the pedicle valve approximately equal in depth to the brachial valve. 

Besides having the pedicle the deeper of the two 

valves, C. h. darwinensis differs from C. hirsuta 

(Hall) in having a broader fold and sulcus (where 

present), slightly less extended umbonal region, and 

coarse vascular grooves. 

C. orbicularis (McChesney), the Pennsylvanian 

species, is closest in size and shape to C. h. darwinensis, but one constant difference is the greater development of the bulges of the posterior margin of 

the pedicle valve at either side of the umbonal 

region. These bulges are set off from the main 

part of the valve by an angulation beyond which 

they extend dorsally a little more than I mm. Viewed 

in side profile, the line of commissure has a distinctly 

sigmoidal curvature, as opposed to the relatively 

straight line of commissure in side profile in C. h. 

darwinensis. No coarse vascular grooves have been 

observed in C. orbicularis. 

Types.-Holotype, USNM I6839I; paratypes, 

I637I2, I68392-I68394, I6845I, UM 6623, UW IT230. 

Figured specimen.-( ?) USNM I68452. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 26b (3), 27 (I), 36a (2), 

36d (2), 43 (I), 44 (2), ?A (I), Fremont County; 

I37 ( 6), Teton County. 

Cleiothyridina aff. C. elegans Girty 

Plate 7, figures 41, 50-53 

Cleiothyridina hirsuta (Hall). Branson and Greger, 1918, p. 

320, pl. 19, figs. 14. 

Two specimens from Cherry Creek are related to 

Girty's species from the Fayetteville Shale of Arkansas. The first, in the University of Missouri 

collection, was figured by Branson and Greger as 

the Meramec species C. hirsuta (Hall), which it 

resembles in having the pedicle valve equally as deep 

as or slightly deeper than the brachial valve. Comparison with specimens of C. hirsuta from the Salem 

Limestone at Spurgeon Hill, Ind., shows that the 

Amsden shell is more suboval in shape transversely, 

having a slightly shorter umbo, and the posterolateral margins forming an obtuse angle. A narrow 

shallow median sulcus depresses the anterior part 

of the pedicle valve, but a corresponding fold cannot 

be seen on the brachial valve. The internal mold 

of the pedicle valve is marked, near the anterior 

margin, by faint radial lirae of which seven or 

eight occur in the space of 2 mm. If these are 

vascular markings, they are much finer than those 

on C. darwinensis n. sp. They might, however, be 

impressions of the radially !irate structure observed 

commonly in shells of athyridaceans, including 

some species of Cleiothyridina. 

The second specimen, in the collection of the 

University of Wyoming, was listed by Shaw and 

Bell (I955, fig. I) in an annotated columnar section 

of the lower part of the Amsden Formation at 

Cherry Creek as "Torynifer cf. T. setigera." It retains part of the outer shell of the pedicle valve, 

which preserves the fine concentric lamellae and 

tiny spine fringes of Cleiothyridina and does not 

have the coarse spine rows of Torynifer. The anterior part of this specimen is broken, which requires 

the slight addition by estimation of its length given 

below. 

The dimensions of the two specimens (UM 2654 

and A 205, respectively) are as follows: length I1.9 

and I3 mm (estimated), width I2.4 and I4.4 mm, 

thickness (both valves) 6.0 and 7.0 mm. 

These shells appear to be intermediate between 

C. hirsuta (Hall) and C. elegans (Girty). They are 

more transverse than typical C. h. darwinensis and 

lack the prominent vascular grooves seen in that 

form. 

Figured specimen.-UM 2654. 
D58 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Mentioned specimen.-UW A205. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 29 (1), 36a (1), Fremont County. 

Cleiothyridina aff. C. sublamellosa (Hall) 

Plate 7, figure 37 

This record is based upon one young specimen 

and four pedicle valves from two localities in the 

Moffat Trail Limestone Member. The largest specimen measures (in mm) 11.0 long, 13.0 wide, and 

3.6 deep; the smallest is 5.6 long, 6.5 wide, and 2.8 

deep. The largest is figured and resembles shells 

from Heath Formation of Montana that were identified by Easton (1962, p. 75, pl. 10, fig. 18) as 

Cleiothyridina aff. C. sublamellosa (Hall). It is a 

little wider in proportion to its length than the 

Horseshoe Shale Me,mber form, C. hirsuta darwinensis but it has approximately the same depth. 

This lot was identified under this title by G. H. 

Girty. 

Figured specimen.-USNM 168453. 

OccutTence and number of specimens.-Moffat 

Trail Limestone Member : collections 73 ( 1) , 93 ( 4) , 

Lincoln County. 

Cleiothyridina sp. indet. 

Poorly preserved specimens from beds of Pennsylvanian (Morrowan) age are recognized as belonging in Cleiothyridina but are not identifiable as 

species. It has been the custom among American 

Carboniferous paleonotologists to refer all Pennsylvanian shells of this genus to one species, C. orbiculat·is (McChesney). Although the size, shape, and 

what can be .seen of the ornamentation of these Amsden shells does not preclude .such an assignment, not 

enough characters are preserved to enable a positive identification. 

Occwrrence and number of specimens.-Horseshoe 

Shale Member, collections 1 (1), 2 (1), 3 (2), Carbon County. Ranchester Limestone Member, 131 (1), 

139 (1), Teton County. 

Genus COMPOS IT A Brown, 1849 

Composita aff. C. laevis Weller 

Pla1te 8, figures 1-5, 43 

Composita laevis Weller, 1914, p. 491, 492, pl. 82, figs. 14-20. 

Specimens of Composita in a shaly limestone bed 

in the lower part of the Amsden section in Hoback 

Canyon somewhat resemble Weller's species. The 

shells are small, subcircular to elongate-oval in outline, and because of their shape can easily be mistaken for small terebratuloids such as Girtyella and 

Cranaena, except that the shall structure is fibrous 

and impunctate. Pedicle valves are longer than wide, 

widest a little anterior to and deepest a little posterior to midlength. The median sulcus is shallow, 

beginning near midlength or a little farther back on 

some specimens. The sulcus causes a moderate 

rounded deflection in the anterior line of commissure, and the anterior outline is nearly fiat or faintly 

emarginate medially. The umbo is strongly curved 

and the beak erect to incurved. 

Brachial valves are low in the region of the beak, 

shallower overall than pedicle valves; no fold is 

present on most shells, but some have a very faintly 

elevated medial anterior area. Some valves steepen 

along the anterior margin in the manner of terebratuloids. Surface sculpture is smooth on both 

valves except for fine concentric growth lines; most 

shells, however, are decorticated. 

Internally, the pedic.le valve has a pair of fairly 

strong dental plates posteriorly. Longitudinal vascular groves of the type common in Composita are 

strongest in the medial parts of the shell and taper 

anteriorly; Most prominent is a pair of grooves, 

one at either side of the sulcus. Some brachial valves 

have a faint medial lira posteriorly that does not 

reach the height of a true median septum. 

Dimensions (in mm) .-

Pedicle valves Brachial valve. Both valves 

Length ----- Width _____ _ 

Thickness __ _ 

Depth _____ _ 

USNM USNM 1J68.~97 1J68398 

13.3 

12.0 

3.7 

10.0 

7.7 

2.8 

1 USNM 168397-168399 a.re from collection 117. ~ USNM 16839'6 is from collection 118. 

USNM USNM 1 168399 2 168396 

2.2 

8.7 

7.8 

5.7 

The Wyoming shells differ from Kentucky speciments of C. laevis Weller in being a little less 

slender on the average, having a slightly flatter 

brachial valve and a shallower emargination or 

mere flattening anteriorly. Nevertheless, they seem 

closely related to Weller's species. 

These specimens are not conspecific with those 

described and figured as C. laevis by Easton (1962, 

p. 76, 77, pl. 11, figs. 1a-2b) from the Heath Formation of Montana, herein regarded as immature speciments of C. subquadrata (Hall). These young shells 

that Easton identified as C. laevis have been compared with C. farrelli Gunnel from the so-called 

Brazer Limestone, particularly with a possible paratype in the U.S. National Museum collection (USNM 

137560), and appear to be conspecific. Our Wyoming specimens of C. aff. C. laevis also have been 

compared with C. farrelli; they are not conspecific. 

Easton included C. farrelli in the syonymy of C. 

laevis, which is not correct but applies so far as the 

Montana specimens are concerned. For the reason 

stated above, C. farrelli actually belongs in the 
BRACHIOPODA OF THE AM8DEN FORMATION D59 

synonymy of C. subquadrata. Hernon (1937, p. 

689), who recorded C. laevis in the Paradise Formation of Arizona, did not describe and figure the specimens. 

Figured specimens.-USNM 168396, 168397. 

Additional measured specimens.-USNM 168398, 

168399. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: coiiections 1 (1) 2 (1), 3 (2), Car-

(118), Teton County. 

Composita subquadrata (Hall) 

Plate 8, figures 31-35, 49; plate 9, figures 37-41 

Athyris subquadrata (Hall), 1858, p. 703, 708, pl. 27, figs. 

2a-d, text fi.g. 118; Whitfield, 1891, p. 585, pl. 14, figs. 

1-3; 189·3, p. 472, pl. 10, figs. 1-3; Keyes, 1895, p. 92; 

Weller, 1897, p. 258, pl. 19, fig. 16. 

Athyris subquadrata Hall? Hall and Whitfield, 1877, p. 271, 

pl. 5, figs. 19, 20. 

Seminula subquadrata (Hall). H~.ll and Clarke, 1893 [part], 

p. 95; 1894 [part], pl. 35, figs. 13, 15; 1895 [part], 

p. 95, pl. 84, figs. 30, 31 [not pl. 47, figs. 7-9, 15, 16,], 

Grabau and Shimer, 1909, p. 354; Bassler, 1909, pl. 

29, figs. 6-8; Morse, 1911, p. 383, figs. 13a-c. 

Composita subquadrata (Hall). Weller, 1914, p. 489, 490, 

pl. 81, figs. 1-15; Girty, 1915b, p. 72, pl. 4, figs. 15-

16a; Butts, 1917, p. 116, pl. 28, figs. 1, 2; Weller, 

1920, p. 375, pl. 11, figs. 12-14; Butts, 1926, p. 198, 

pl. 65, figs. 10-12; Croneis, 1930, p. 74, pl. 19, figs. 

27-29; Weller, 1931, pl. 44, figs. 4a, b, c; Butts, 1941, 

p. 241, pl. 30, figs. 16-18; Easton, 1942, pl. 8, figs. 7, 

8; Cooper, in Shimer and Shrock, 1944, p. 335, pl. 28, 

figs. 13-15; Weller and others, 1952, p. 95, pl. 2, figs, 

32, 33; Allen and Lester, 1954, p. 89, 105, 111, pl. 23, 

fig. 5; pl. 27, fig. 4; pl. 28, fig. 33; Grinnell and 

Andrews, 1964, p. 232. 

Composita subquadrata (Hall)? Girty, 1920, p. 651, pl. 53, 

figs. 9, 9a. 

Composita farrelli Gunnell, 1932, p. 299, pl. 27, figs. 45, 47, 48. 

Composita laevis Weller. Easton, 1962, p. 76, 77, pl. 11, figs. 

1a-2b. 

Composita ozarkana Mather. Easton, 1962, p. 77, pl. 11, figs. 

5a-7b. 

Composita. sulcata Weller. Easton, 1962, [part], p. 77, 78, 

pl. 11, figs. 8a-9b. 

Description.-Medium-sized Composita, subquadrate in outline owing to approximately equal length 

and width, occurrence of greatest width approximately at midlength, divergence of posterior margins 

at about 90°, and slight extension of fold and sulcus 

beyond curve of anterior margin. Sulcus in pedicle 

valve beginning about 6 or 7 mm in front of beak 

and continuing rather shallowly to anterior margin, 

where Iinguaform projection of anterior margin extends into fold, causing moderate to deep rounded 

deflection of anterior line of commissure. Moderatesized Amsden specimen is 20.5 mm long, 20 mm 

wide, and 11.5 mm thick. 

Discussion.-This species occurs in the Amsden 

Formation only in western Wyoming where it has 

been recognized in the Horseshoe Shale and Moffat 

Trail Limestone Members. Specimens illustrated on 

plates 8 and 9 are from a locality in the Washakie 

Range. 

C. subquadrata is a ubiquitous Chesterian species 

found in many areas in the United States. It seems 

to grade on the one hand into C. trinuclea (Hall) 

and on the other into C. sulcata Weller. When these 

taxa, however, are viewed from the standpoint of 

their being populations having overlapping variants, 

their separate entity is rather easily discerned because most of the typical specimens can be readily 

distinguished. 

The subquadrate outline of this species is most 

apparent when the shell is viewed after having been 

rotated 45° from its median axis along the plane of 

commissure. 

C. subquadrata is very common in the Heath Shale 

of Montana but, as pointed out in the discussion of 

C. aff. C. laevis, the shells were described by Easton 

under several other names. The lot of specimens 

(USNM 14232) from the Oquirrh Mountains, Utah, 

collected by the 40th Parallel Survey in rocks of 

Late Mississippian age, described and figured by 

Hall and Whitfield (1877) as "Athyris subquadrata 

Hall?," and by Girty (1927) as "Composita subquadrata (Hall) ?" have been reexamined and found 

to be conspecific with the shells described here. 

Figured specimens.-USNM 168429-168432. 

Occun·ence and number of specimens.-Horseshoe 

Shale Member: collection 41 (46), Teton County. 

Moffat Trail Limestone Member: collections 76 (1), 

93 (2), Lincoln County; 145 (12), Teton County. 

Composita sigma n. sp. 

Plate 8, figures 21-30, 36-39; plate 9, figures 21-30. 

?Martinia n. sp. Branson and Greger, 1918, p. 319, pl. 19, 

figs. 17, 18. 

Diagnosis.-Smaii to medium-sized Composita, 

subcircular to elongate oval in outline; sulcus prominent only on middle of anterior one-third of pedicle 

valve. Fold tending to flare slightly at anterior margin, delimited by pair of faint sulci on anterior onefifth of brachial valve. 

Desc1·iption.-Pedicle valve somewhat variable in 

shape, having length equal to, less than, or slightly 

greater than width; greatest width at or near middle; greatest thickness posterior to middle; convexity moderate, in side profile having greatest 

curvature at umbo and gradually decreasing anteriorly; in posterior profile moderately to gently 
D60 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

arched, flatter over sulcus. Sulcus narrow and shallow in posterior half of valve, not developed at all 

on some specimens, more prominent on anterior 

one-third of valve where it is broadly V-shaped, 

reaching not quite one-half width of valve at anterior margin, slightly produced in linguaform 

tongue extending a little beyond curvature of margin 

in some specimens, producing moderately deep 

rounded deflection of line of commissure anteriorly. 

Umbo rathe·r low, curving strongly dorsad; beak 

incurved; posterior margins diverging at angles 

ranging from 90° to 110°. Surface smooth except 

for several faint ·concentric grooves on shell and 

fairly strong lamellae near anterior margin. 

Brachial valve about as convex as pedicle valve 

Dimensions (in mm).-

and similar in outline; in side profile having greatest 

curvature near beak, greatest depth one-third of way 

forward from beak, and becoming slightly concave 

near ante·rior margin on most specimens so that 

profile from beak to tip of fold follows sigmoidal 

curve; moderately arched in posterior profile, having 

greatest curvature· over middle of valve, becoming 

more gently on flanks. Line of commissure depressed 

slightly at either side of fold. Ornamentation same 

as on pedicle valve. 

Internally, pair of short dental plates present in 

pedicle valve; umbonal cavity rather shallow owing 

to incurving of beak. Brachial valve has narrow 

medial lira dividing muscle field. Hinge plate not 

seen. 

USNM USNM YPM YPM YPM USNM USNM USNM USNM YPM USNM USNM 1 168416 1 1681.17 2 20109b 2 20109c 2 20109d 1 168418 1 168419 2 168411 2168~12 2 20109a 2 168413 2 168414 

Length ---------------- 17.5 15.5 15.5 15.0 14.8 14.7 14.5 14.2 13.3 12.2 11.9 10.9 

Width ---------------- 16.2 15.0 14.1 14.8 12.5 13.3 15.0 14.4 11.7 12.0 12.0 10.4 

Thickness ------------- 11.4 10.5 8.4 9.1 9.5 9.5 8.5 8.6 7.8 7.0 7.3 6.6 1 USNM 168416-168419 are from Livingston Ranch (colin. 45). 2 USNM 168411-168414 and YPM 20109a-d are from Wiggins Fork (collns. 47, 48). 

Discussion.-This species is based upon specimens 

from Wiggins Fork in the Washakie Range, supplemented by additional material from Livingston 

Ranch in the same range. Designated paratypes are 

in the U.S. National Museum and Yale University 

Peabody Museum collections. C. sig·ma occurs also 

at Cherry Creek and other localities in the Wind 

River Range, where it is restricted to the lower 

fossiliferous beds of the Horseshoe Shale Member, 

associated with Anthracospirifer welleri we.lleri 

(Branson and Greger). 

C. sigma is recognized by its subcircular to elongate suboval outline, by relative suppression of the 

median sulcus and lack of lateral sulci of fiat flanks 

in the pedicle valve, and by a rather weak short fold 

that tends to flare slightly in the brachial valve. 

The general shape of this species resembles that 

of C. poposiensis n. sp., which seems to be a severally 

sulcate and somewhat subangular modification of it. 

The apparent stratigraphic relations in the vicinity 

of Cherry Creek point to C. sigma as the progenitor 

of C. poposiensis. 

C. sigma has been identified also in western Wyoming in Upper Mississippian beds, including those 

of latest Mississippian age (Zone 19 of Mamet) ; C. 

poposiensis is not found in this part of Wyoming. 

The late forms of C. sigma in this part of the State 

lack the slight flare of the fold normally found in 

Fremont County specimens and the median sulcus 

begins nearer to the umbo on pedicle valves. These 

are characters also found in C. poposiensis, indicating that the western Wyoming forms underwent 

part of the modifications that derived C. poposiensis 

from C. sigma. However, as no highly sulcate forms 

are present in the western Wyoming beds, these 

slightly different shells are regarded merely as variants of C. sigma. 

Included tentatively in C. sigma is a unique shell 

from the Horseshoe Shale Member at Cherry Creek 

which was described as a M artinia by Branson and 

Greger (1918), but does not have the shape of that 

genus. The shell (UM 2652) is figured on plate 8, 

figures 26-30. It is elongate oval in outline, shallowly sulcate, the greatest width approximately at the 

middle, and measures (in mm) : length 8.9, width 

6.8, and thickness 4.5 (allowing for a small part 

that someone has ground off). It appears to be a 

narrow Composita, differing from typical specimens 

of the genus only in that the beak of the brachial 

valve is rather straight and does not curve into and 

occupy the delthyrium of the pedicle valve. It has 

dental plates in the pedicle valve and no median 

septum in the brachial valve. It is referred to C. 

sigma with question as an aberrant specimen of 

this species. 

Comparisons and affinities.-The wider shells of 

C. sigma, having a subcircular outline, somewhat 

resemble shells of C. ovata Mather, a common and 

long-ranging Pennsylvanian species. C. ovata, however, is a larger species having a broad shallow 

medial sulcus and fold that make a rather wide and 

shallow deflection in the anterior line of commissure. 
BRACHIOPODA OF THE AM8DEN FORMATION D61 

In C. sigma this deflection is deeper and narrower 

and flanked by shallow deflections in the opposite 

direction which are caused by the short sulci that 

flank the fold in the brachial valve. 

Types.-Holotype, USNM 168411; paratypes, 

USNM 168412-168421, 168454; YPM 5154b, 20109ad. 

Figured specimen.-UM 2652. 

Occurrence and number of specimens.-Horseshoe Shale Member: collections ?22 (3), 26b (78), 

27 (8), 28 (1), ?29 (1), 36a (116), 36e (1), 39 (33), 

44 (17),45 (159),47 (26),48 (70),B (8),E (22), 

Fremont County; 137 (15), 149 (40), 152 (5), 153 

(8), 154 (25), ?156 (1), ?159 (2), Teton County. 

Rancheste,r Limestone Member: collections 82 ( 45), 

97 (5), Lincoln County; 146 (12), 160 (1), Teton 

County. 

Composita poposiensis n. sp. 

Plate 8, figures 6-20; plate 9, figure,s 1-15, 311-36 

Composita trinuclea (Hall). Branson and Greger, 1918 p. 319, 

320, pl. 18, figs. 1-4. 

Composita subtilita var. subtilita (Hall). Burk, 1954 [part], 

p. 12, pl. 1, figs. 5-7, 12. 

Composita subtilita var. ovata Mather. Burk, 1954 [part], 

p. 12, 13, pl. 1, figs. 2, 4 [not figs. 3, 11]. 

Composita subtilita var. trinuclea (Hall). Burk, 1954, p. 13, 

pl. 1, figs. 8-10. 

Cleiothyridina sp. Burk, 1954 [part], p. 13, pl. 1, fig. 15. 

Diagnosis.-Small to medium-size Composita, typically five- to seven-sided in outline, but varying 

toward elongate suboval or subcircular; greatest 

width anterior to and greatest thickness posterior 

to midlength. Anterior part of pedicle valve having 

deep median sulcus and two shallower lateral sulci 

separated by narrowly rounded ridges ; corresponding part of brachial valve having broadly rounded 

fold set off by broad shallow sulci. 

Description.-Pedicle valve variable in shape and 

outline, length generally greater greater than width, 

Dimensions (in mm).-

but rarely less than width; posterior margins diverging at angles ranging roughly from 90° to 110°; 

lateral margins nearly straight to gently rounded, 

subparallel or diverging slightly so that greatest 

width is a little anterior to midlength; anterior margin rounded, in some specimens divided into three 

parts by protruding fold and sulcus ; boundaries between posterior and lateral margins and lateral and 

anterior margins more strongly rounded, approaching subangular in some specimens. In side profile, 

greatest .convexity near umbo, decreasing toward 

anterior margin; in posterior profile rather flat over 

middle of arch, with sloping srtraight or gently convex flanks. Median sulcus beginning normally 3-5 

mm in front of beak, in some specimens within 1 

mm of beak, and extending to anterior margin 

where it occupies nearly three-fifths of maximum 

width of shell, bounded by strongly rounded diverging ridges; shallower round-bottomed sulcus commonly present on either flank; median sulcus extending forward and causing strong rounded deflection in line of commissure, two gentle deflections 

marking position of lateral sulci. Surface sculpture 

consisting of concentric grooves, Iirae·, and lamellae 

of growth, crossed by very faint tiny radial striae. 

Interior of pedicle valve having pair of dental 

plates within umbonal region; shell thickened and 

pitted just in front of dental plates; heart-shaped 

muscle scar occupies depressed area in middle. 

Brachial valve elongate, suboval to subcircular, 

shallower and less convex in side profile than pedicle 

valve, but equally convex in posterior profile. Fold 

restricted to anterior one-third of valve, flanked by 

pair of broad shallow sulci terminating in fairly 

prominent rounded deflections of line of commissure. 

Sculpture similar to that on pedicle valve. Interior of 

brachial valve having cardinal plate concave on ventral side and indented apically by subconical pit. 

USNM USNM USNM USNM USNM USNM USNM USNM 1 168400 2 168406 2 16840.1 1 168401 2 168404 :: 168407 2 168405 3 168408 

Length ----------------------- 19.7 16.8 16.3 14.7 14.0 12.4 10.9 10.5 

Width ------------------------ 16.4 17.2 13.7 14.7 13.7 11.5 10.5 10.2 

Thickness --------------------- 11.5 10.0 1 USNM 168400 and 1684101 are from Amsden Hill. 2 USNM 168403-168406 are from Enterprise Ditch. a USNM 168407 and 168408 are from the Little Popo Agie River (colin. 38). 

Discussion.-Composita poposiensis n. sp. is 

erected principally for Wyoming shells identified by 

previous workers as "Compos'ita trinuclea (Hall)" 

or "C. subtilita var. trinuclea (Hall)." Also included 

in the new species are some of the specimens identified by Burk (1954) as C. subtil·ita var. subtilita 

(Hall), C. subtilita var. ovata Mather, and Cleiothy9.8 9.3 7.8 7.8 6.2 6.8 

ridina sp. These are all regarded as component parts 

of a single, somewhat variable population. The sulcate trinuclea-like form is by far the most abundant. 

Among 237 specimens in collection 38, 115 ( 481h 

percent) are moderately sulcate; 28 (12 percent) 

deeply sulcate; 45 (19 percent) more rounded and 

with less developed lateral sulci, including both 
D62 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

ovata-like and subtilita-like forms; and 49 (201f2 

percent) are somewhat immature specimens, including many that resemble those referred by Burk to 

Cleiothyridina sp. Of the adult shells, 76 percent belong to the trinuclea-like form. 

The holotype is a well-preserved specimen collected by I. A. Keyte at Amsden Hill. Paratypes have 

been designated from this locality and from Enterprise Ditch, Little Popo Agie River, and Cherry 

Creek. Included among the paratypes are specimens 

figured by Branson and Greger (1918) and by Burk 

(1954). Only the one figured by Branson and Greger 

on their plate 18, figures 1 and 4, is so designated; 

the other, an extreme subtilita-like form (figures 2 

and 3 on the same plate) is missing and has not been 

available for study. 

C. poposiensis is rather easily distinguished from 

C. trinuclea (Hall) by a constant difference in outline. A well-preserved specimen of C. trinuclea 

(USNM 168422) from the Pella beds of late Meramecian age, 41;2 miles south of Pella, Iowa, is figured 

in this report on plate 9, figures 16-20. In Hall's 

species the outline of the shell is subtriangular to 

subrhombic, the posterior margins extending forward from the beak and curving into the lateral 

margins without a noticeable break as far as the 

point of greatest width, a little in front of midlength. In typical C. poposiensis, the outline, although somewhat rounded, ranges from subpentagonal through subseptagonal, the lateral margins 

being subparallel or diverging slightly. A noticeable 

change in direction of gentle subangulation normally marks the boundary between the posterior and 

lateral margins in this species. 

This feature is seen in all but the most extreme 

subtilita-like shells, which are relatively rare, and it 

raises the question whether these exceptions are correctly included in C. poposiensis. The principal evidence available in this regard is incorporated in a 

bilaterally asymmetrical specimen from the valley of 

Little Popo Agie Creek figured on plate 9, figures 

6-10. The right half of this specimen has an outline 

showing a slight deflection at the boundary between 

the posterior and lateral margins; because of this it 

is poposiensis-like in shape. The left half has the 

posterior margin passing into the lateral margin 

without a break, as in C. subtilita. Mainly because 

of this specimen the extreme subtilita-like forms are 

here included in C. poposiensis. No specimens identical with typical C. trinuclea from the American midcontinent have been found at the Wyoming localities. 

The typicaJ form of this species, having a trisulcate pedicle valve, is not known outside Fremont 

County, and specimens from Horse Creek in the 

Washakie Range are the only ones known outside the 

Wind River Range. Nearly all the specimens of C. 

poposiensis are silicified and chert filled, and most, 

if not all, of these have probably come from the 

upper zone in this region, which we are calling the 

Composita poposiensis Subzone. The only known 

occurrence of this species in the Carlinia amsdeniana Subzone is a pedicle valve collected in place in 

sandstone at Cherry Creek (colin. 31) by W. G. Bell, 

a former student at the University of Wyoming, in 

the Horseshoo Shale Member, 47-48 feet above the 

base of the Amsden Formation. 

Types.-Holotype, USNM 168400; paratypes, 

USNM 168401-168410 (18 paratypes), UM 2655, 

UW IT-211, IT-212, IT-215, IT-221, IT-222. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 26a (9), 26b (120), 31 

(1), 32 (33), 34 (6), 35 (240), 36a (105), 36e 

(128), 38 (237), 42 (27), 43 (10), A (21), B (14), 

Fremont County. 

Composita sulcata Weller 

Plaite 8, figures 40~42, 44-48, 50-54 

Composita sulcata Weller, 1914, p. 490, 491, pl. 82, figs. 1-10; 

Girty, 1927, p. 64, pl. 23, figs. 28-33; Easton, 19'62, p. 

77, 78, pl. 11, figs. 8a-9b; Grinnell and Andrews, 19,64, 

p. 232. 

Cmnposita subtilita var. subtilita (Hall). Burk, 1954 (part], 

p. 12 [not pl. 1, figs. 5-7, 12]. 

Composita subtilita var. ovata Mather. Burk, 1954 (part], 

p. 12, 13, pl. 1, figs. 3, 11 [not figs. 2, 4]. 

Diagnosis.-Medi urn-sized C om.posita, subquadrate to subcircular in outline, having sulcus that 

begins shallowly and deepens rapidly, causing very 

prominent rounded medial deflection in line of 

commissure. 

Description.-Pedicle valve having length generally slightly greater than width, rarely equal to 

width; greatest width at or slightly anterior to midlength; greatest thickness posterior to midlength. 

Posterior margins diverging at angles from 95° to 

115°, curving forward slightly to meet well-rounded 

lateral margins ; anterior margin more gently convex. In side profile, curvature of valve rather gentle 

and even, except at anterior end where prolongation 

of sulcus curves strongly to fit into fold of brachial 

valve; in posterior profile rather evenly convex. Sulcus beginning about 5 mm in front of beak, Vshaped, narrow, shallow, and relatively inconspicuous up to length of 10 to 12 mm, then deepening 

rather rapidly to form strong rounded deflection in 

line of commissure. Surface of valve smooth, marked 

only by concentric growth lines and by several 
BRACHIOPODA OF THE AMSDEN FORMATION D63 

strong lamellae of growth near anterior margin. 

Umbonal region strongly convex; beak erect to 

in curved. 

Brachial valve transversely oval in outline; in 

side profile with greatest curvature at beak and 

lessening to anterior margin, or shallowly concave 

near anterior margin so that profile along medial 

line follows sigmoidal curve; in posterior profile 

narrowly arched medially with fairly straight or 

gently convex sloping flanks. Fold becomes clearly 

Dimensions (in mm).-

USNM 

1 168425 

L,ength ----------------------- 20.2 

Width ------------------------ 20.7 

Thickness --------------------- 11.4 1 USNM 168427 is from Cherry Creek. 2 USNM 168423 and 168424 are from Enterprise Ditch. 3 USNM 168427 is from Cherry Creek. 

USNM 

2 168423 

18.1 

19.7 

10.5 

i USNM 168428 is from the Little Popo Agie River (colin. 38). 

Discussion.-Shells of C. sulcata from the Amsden 

Formation resemble examples from the central 

Mississippi Valley region rather closely. Specimens 

from the so-called Brazer Limestone of Idaho identified by Girty (1927) as C. sulcata are somewhat 

thicker and have a longer and deeper sulcus in the 

pedicle valve) representing perhaps a subspecies of 

C. sulcata. 

This species is distinguished from C. poposiensis 

n. sp., with which it occurs, by its subcircular to 

suboval shape, width normally greater than length, 

lack of lateral sulci and narrow bordering radial 

ridges in the pedicle valve, having long posterior 

margins that curve into the lateral margins without 

a clearly defined break in curvature, and by the very 

deep deflection of the line of commissure in mature 

specimens. Immature specimens are more difficult to 

distinguish from the less deeply sulcate forms of C. 

poposiensis, but are recognized by their wide shells 

and late-beginning median sulcus in the pedicle 

valve. 

Figured specimens.-VSNM 168423, 168424, 

168455. 

Additional measured specimens.-VSNM 168425-

168428. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 26a (5), 26b (10), ?34 

(1), 35 (9), 36a (15), 36e (9), 38 (33), 42 (5), 43 

(2), A (5), B (2), C (2), E (1), Fremont County. 

Composita ovata Mather 

Plate 10, figures 1-15, 26-32 

Composita ovata Mather, 1915, p. 212, 213, pl. 14, figs. 6-6c; 

Dunbar and Condra, 1932, p. 370, 371, pl. 43, figs. 14-

19; Gehrig, 1958, p. 13, pl. 5, figs. 5-13, 24-27, 38-40; 

Hoare, 1961, p. 90, 91, pl. 12, figs. 3, 4; Grinnell and 

delimited only in anterior third of shell. Sculpture 

as in pedicle valve. 

Interior of pedicle valve having pair of fairly 

short dental plates enclosing moderately deep urnbona! cavity; shell pitted in small area at either side. 

Interior of brachial valve having cardinal plate supported apically by short, fairly broad, low median 

buttress just in front of which dorsal side of plate is 

penetrated deeply by long narrow funnel-shaped pit; 

ventral side of cardinal plate not seen. 

USNM USNM 3 168427 2 168424 

17.5 15.6 

17.6 16.8 

10.7 9.5 

USNM 

1168426 

14.2 

14.2 

8.1 

USNM 

4 168428 

10.9 

11.3 

6.3 

Andrews, 1964, p. 234-236, pl. 39, figs. 1, 2, 7, 8; 

Sturgeon and Hoare, 1968, p. 57, 58, pl. 18, figs. 11-18. 

Composita subquadrata (Hall). Easton, 1962, p. 78, 79, pl. 

11, figs. 10-18. 

Diagnosis.-Medium-sized Composita having subovate shell, greatest width at or just anterior to middle; sulcus shallow; fold low and broad. Pedicle valve 

moderately convex; brachial valve suboval to subcircular in outlines, approximately as convex as 

pedicle valve. 

Discussion.-This is the common species of Composita in Amsden beds of Early Pennsylvanian 

(Morrowan) age. It is widely distributed in beds of 

Early Pennsylvanian age throughout the western 

United States. Specimens from the Alaska Bench 

Limestone of central Montana were described and 

figured by Easton (1962, p. 78, pl. 11, figs. 10-18) as 

Composita subquadrata (Hall). 

The western specimens tend to be slightly more 

tumid than topotypes from the Morrowan Series in 

Arkansas, but their outline is about the same as that 

of the Arkansas shells. Perhaps the western form 

should be considered a geographic subspecies of 

typical C. ovata, but degree of tumidity, where this 

character is not excessive, is a will-of-the.-wisp criterion upon which to base demarcation of a formal 

taxon. 

Recent studies by Hoare (1961) and Sturgeon and 

Hoare (1968) have shown that this species ranges 

in Ohio from the lower Mercer Limestone of the 

Pottsville Group up to the Ames Limestone of the 

Conemaugh Group. 

Dunbar and Condra (1932, p. 370, 371, table D) 

recognized this species at various levels throughout 

the Pennsylvanian rocks of Nebraska and Kansas, 
D64 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

ranging as high as the Lower Permian Wabaunsee 

Group. 

The low broad sulcus and fold, causing only a 

shallow deflection in the anterior line of commissure 

is very characteristic of this species. Differences 

from C. sigma n. sp. are discussed under that 

species. 

Figured specimens.-VSNM 168434-168439. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 2 (1), 3 (8), ?4 (1), 5 

( 1), Carbon County. Ranchester Limestone Member: collections 13 (21), 14 (66), Carbon County; 

68 ( 4), Sheridan County; ?87 ( 1), Lincoln County; 

?130 (2), 131 (12), ?139 (1), 143 (5), Teton 

County. 

Composita elongata Dunbar and Condra 

Plate 10, figures 16--25 

Composita subtilita (Hall). Sayre, 1930 [part], p. 102, pl. 

6, figs. 4-6c [not 7-8c]. 

Composita elongata Dunbar and Condra, 1932, p. 371, 372, pl. 

43, figs. 20-24; Grinnell and Andrews, 1964, p. 236, 

pl. 37, figs. 5, 6; pl. 38, figs. 5, 6; pl. 39, figs. 5, 6, 11, 

21; Sturgeon and Hoare, 1968, 59, pl. 19, figs. 1-3. 

Description.-Shell moderately small to medium 

sized having greatest width at or slightly anterior to 

midlength, maximum thickness slightly posterior to 

midlength; thickness approaching and in some specimens equaling width. Pedicle valve elongate oval in 

outline, rather strongly convex in side profile and 

more strongly convex in posterior profile. Sulcus 

shallow, arising about 10 mm in front of beak, meeting fold of brachial valve to produce moderately 

deep evenly rounded deflection in line of commissure. 

Beak incurved; posterior margins diverging at 

angles of 75o to 80°. Brachial valve suboval, shallower and less convex in side profile than pedicle 

valve but more narrowly arched in posterior profile; 

beak curving into delthyrium of pedicle valve, fold 

low and moderately broad, occupying most of anterior end. Surface of both valves smooth, marked by 

concentric grooves and lines of growth. Internal 

characters not observed. 

Dimensions (in mm).-

Length _____________________ _ 

Width -----------------------

Thickness --------------------

USNM 

168440 

19.3 

14.7 

14.7 

USNM 

16841,.1 

18.7 

13.3 

12.5 

Discussion.-The specimens described and figured 

from the Amsden Formation occur in a collection of 

Pennsylvanian (Morrowan) age in the R.awlins hills. 

They were found associated with C. ovata (Mather) 

and may intergrade with that species. Another specimen was found with C. ovata Mather at Hoback 

Canyon. 

According to Sturgeon and Hoare (1968, p. 59), 

C. elongata intergrades with C. subtilita (Hall) in 

rocks of the Allegheny and Conemaugh Formations 

in Ohio. Grinnell and Andrews recognized C. elongata in the Missourian and Virgilian (Pennsylvanian) and Wolfcampian (Permian) Series. This 

evidence indicates that C. elongata may actually be a 

form species, composed of narrow variants of more 

than one species of Composita, in Pennsylvanian and 

Lower Permian rocks. The Amsden shells constitute 

the earEest known record of this form. 

Figured specimens.-VSNM 168440, 168441. 

Occu1Tence and number of specimens.-Horseshoe Shale Member: collection 3 (7), Carbon County. Ranchester Limestone 1\tlember: collection 131 

( 1) , Lincoln County. 

Composita subtilita (Hall) 

Plate 10, figures 33-37 

Terebratula snbtilita Hall, 1852, p. 409, pl. 4, figs. 1a, b, 

2a-e. 

Composita subtilita (Hall). Girty, 1915a, p. 96-101, pl. 12, 

figs. 4-4c; pl. 5, fig. 7; pl. 6, fig. 13 (s,ee for synonymy 

prior to 1915) ; Price, 19'16, p. 706; Girty, 1920, pl. 54, 

figs.27, 28; Price, 1921, p. 778 ?Plummer and Moore, 

1921, pl. 6, fig. 17; pl. 19, fig. 7; Morningstar, 1922, p. 

192, 193, pl. 8, figs. 10-13; Thomas, 1924, p. 4 78, pl. 2, 

figs. 23, 28-30; Morgan, 1924, pl. 42, figs. 13, 13a; 

Butts, 1926, p. 200, pl. 66, figs. 17, 18; Shimer, 1926, 

p. 78; Girty, 1927, pl. 27, figs. 34-36; Sayre, 1930, 

[part], p. 102, pl. 6, figs. 7-8e [not figs. 4-6c]; Branson, 1930, p. 38, pl. 9, figs. 8-11; King, 1930, p. 130, 

pl. 43, fig. 20, pl. 44, figs. 1, 2; Kelly, 1930, p. 147; 

Croneis, 1930, pl. 27, figs. 12-15; Morse, 1931, p. 314, 

pl. 50, fig. 6; Dunbar and Condra, 1932, p. 363-366, 

pl. 43, figs. 7-13; McKee, 1938, p. 262, 263, pl. 48, fig. 

20; Cooper, in Shimer and Shrock, 1944, p. 335, pl. 

128, figs. 9-12; Branson, 1948, p. 323; Allen and Lester, 1954, p. 19, 20, pl. 2, fig. 12; Gehrig, 1958, p. 13, 

14, pl. 5, figs. 14-23, 28-37; Hoare, 1961, p. 89, 90, 

pl. 11, figs. 20-25; pl. 12, figs. 1, 2; Grinnell and 

Andrews, 1964, p. 235-237, pl. 37, figs. 3, 4, 7, 10, 11; 

pl. 38, figs. 1, 2; pl. 39, figs. 3, 4, 9, 10; Boucot and 

others, in Moore, 1965, p. H662, figs. 537, 2a-c; Sturgeon and Hoare, 1968, p. 57, pl. 18, figs. 5-1:0. 

Seminula s1tbtilita (Hall). French, 1940, p. 328, pl. 3, fig. 22. 

Description.-Small to medium-sized Composita, 

suboval to subtriangular in outline, having greatest 

width anterior to and greatest thickness posterior to 

midlength; posterolateral margins forming acute 

angle. Sulcus and fold weak posteriorly and pronounced anteriorly, forming moderately deep rounded deflection in line of commissure. Beak in pedicle 

valve high, incurved, pierced at tip by circular foramen; beak in brachial valve small, buried in delthyri urn of pedicle valve. 
BRACHIOPODA OF THE AMS.DEN FORMATION D65 

Discussion.-This ubiquitous species is not particularly common in the Amsden Formation of Wyoming. The specimen figured, from a bed of probable 

Morrowan age in the Gros Ventre Range, is typical. 

Two occurrences are in beds of Atokan age in the 

Rawlins hills. 

Figured specimen.-VSNM 168433. 

Occurrence and number of specimens.-Ranchester Limestone Member: collections 6 (28), 15 (5), 

Carbon County; 136 (13), 141 (1), Teton County. 

Suborder SPIRIFERIDINA 

Superfamily RETICULARIACEA Waagen 

Family EL YTHIDAE Fredericks 

Genus TORYNIFER Hall and Clarke, 1894 

T orynifer setiger (Hall)? 

Plate 13, figures 47, 48 

Spirifer setigerus Hall, 1858, p. 705, pl. 97, figs. 4, 4a; Hall 

and Clarke, 1893, p. 21, 37; 1895, pl. 36, figs. 26, 27. 

Spirifera setigera Hall. Hall and Whitfield, 1877, p. 270, 

pl. 5, figs. 17, 18; Hall, 1883, pl. ( 36) 61, figs. 26, 27; 

Keyes, 1895, p. 83. 

Reticularia setigerus (Hall). Beede, 1906, p. 1318, pl. 21, 

figs. 1, 1a. 

Reticularia setigera (Hall). Weller, 1914, p. 431-433, pl. 74, 

figs. 12-22; ?Girty, 1951b, p. 65, 66, pl. 4, fig. 6; 

Snider, 1915, p. 91; Branson, 1918, p. 102, pl. 4, figs. 

14, 15; Girty, 1920, pl. 53, figs. 11, 12; ?Shimer, 1926, 

p. 67; Croneis, 1930, pl. 18, fig. 8, pl. 19, figs. 5, 6; 

Weller, 1931, pl. 43, figs. 9a, b; GunneH, 1932, pl. 27, 

figs. 37, 38; Hernon, 1935, p. 688. 

Torynifer setigera (Hall). Cooper, in Shimer and Shrock, 

1944, p. 327, pl. 126, figs. 13-15. 

Torynifer setiger (Hall). Minato, 1953, p. 70, 71. 

An incomplete external mold of a brachial valve, 

from Livingston Ranch measuring approximately 23 

mm long and 32 mm wide when complete, agrees in 

shape, size, and ornamentation with Hall's species. 

A latex cast of this specimen is figured and shows the 

concentric rows of spine bases clearly. The question 

mark applied to this identification records only a 

lack of material sufficient to verify the characters of 

the pedicle valve and of internal structure. Also belonging here is a young specimen about 9 mm long, 

from the Gros Ventre Range. 

Figured specimen.-VSNM 168456. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: coUections 28 ( 1), 45 ( 1), Fremont 

County; 137 (1), Teton County. 

Superfamily SPIRIFERACEA King 

Family SPIRIFERIDAE King 

Genus ANTHRACOSPIRIFER Lane, 1963 

Anthracospirifer curvilateralis curvilateralis (Easton) 

Pla~te 11, figures 1-5 

Spirifer curvilateralis Easton, 1962, p. 68-70, pl. 9, figs. 14-

19. 

Spirifer increbescens Hall. Easton, 1962, p. 70, pl. 9, figs. 

20a, b. 

Spi,rifer shoshonensis Branson and Greger. Easton, 1962 

[part], p. 70, pl. 9, figs. 21a-c [not figs. 22a, b]. 

This species, here considered the typical subspecies, was described in detail by Easton in his report on the Carboniferous formations and faunas of 

central Montana. Its shell resembles that of Anthracospirifer increbescens (Hall) but normally is a 

little less transverse. 

Easton's holotype, a specimen in early maturity, 

has the greatest width about 3 mm anterior to the 

hinge line, as do many other Late Mississippian examples of this species. Some Late Mississippian 

shells from the Heath Formation of Montana and 

most Pennsylvanian specimens referred to this species from formations overlying the Heath have their 

greatest width at the hinge line and their cardinal 

extremities acute. The lateral margins are wellrounded except just in front of the hinge, where they 

are pinched in slightly. The umbonal region extends 

well beyond the hinge line; the umbo is strongly incurved and overhangs the interarea. 

On the typical mature shell, 5 costae occur in the 

sulcus, 6 on the fold, and 12 to 16 on each lateral 

slope. According to Easton, the number of costae 

ranges from 3 to 7 in the sulcus and 10 to 18 on each 

lateral slope. The average dimensions of seven mature specimens recorded by Easton are 23.3 mm long, 

29.2 mm wide, and 18.2 mm thick. 

A specimen from the Heath Formation of Montana figured by Easton (1962, pl. 9, figs. 21a-c) as 

Spirifer shoshonens,is Branson and Greger came 

from the same collection as the primary types of A. 

curvilateralis. It is more alate than is typical in A. 

curvilater-alis and in that respect resembles specimens from the "Cameron Creek" [actually from a 

Mississippian unit] assigned to A. cur-vilateralis by 

Easton. Three costae, the third to fifth to the left of 

the median sulcus give off a weaker plication admedially in this specimen. No similar splitting occurs on the right-lateral slope, the shell having 16 

plications on one side of the sulcus and 13 on the 

other. 

Easton's "Spir,ifer- shoshonensis" is a pathologic 

specimen, regarded here as a topotype of A. curvilateralis. It does not closely resemble the syntypes of 

Anthracospirifer shoshonensis (Branson and Gre--

ger), with which I have compared it, differing in the 

A. increbescens-like shape and the narrowly rounded 

costae that are separated by rounded furrows. A. 

' shoshonensis has subangular costae separated by Vshaped furrows and a narrow and very shallow 

median sulcus indenting a rather deep pedicle valve. 

It is a characteristic species in the Bull Ridge Me1n-
D66 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

ber of the Madison Limestone and is restricted to 

rocks of early Meramecian age. 

Another rather alate Anth1·acospirifer from the 

Cameron Creek Formation was figured by Easton 

(1962, p. 70, pl. 9, fig. 20a, b) as Spirifer increbescens Hall. This specimen, which has 7 costae in the 

sulcus and 15 on each lateral slope on the pedicle 

valve, was the only central Montana example referred by Easton to Hall's species. In my opinion, it 

falls within the range of variation of A. curvilateralis rather than that of A. increbescens, although the 

two are closely related species. 

Although most of the A. cu1·vilateralis-like spirifers in the Moffat Trail Limestone Member of the. 

Amsden Formation belong in a new coarse-ribbed 

subspecies, described below, specimens at three localities resemble the holotype of A. curvilateralis in 

shape and have 12 to 14 costae on each lateral slope. 

These more finely costate specimens are referred to 

A. curvilateralis curvilate1·alis. 

Figured specimen.-VSNM 167735. 

Occurrence and number of specimens.-Moffat 

Trail Limestone Member: collections 92 ( 1) Lincoln 

County; ?121 (2), 145 (55), Teton County. 

Anthracospirifer curvilateralis brutus n. subsp. 

Pla.te 11, figures 6-12 

Diagnosis.-Moderate-sized, rather tumid Anthracospirifer having strongly convex lateral slopes as in 

A. curvilateralis Easton, but more coarsely ribbed, 

17 to 25 costae occurring typically on pedicle valves. 

Description.-Pedicle valve strongly convex, 

greatest convexity near umbo, and lessening toward 

anterior margin; subcircular to transversely suboval 

in outline; greatest width at or just anterior to 

hinge; in posterior view, lateral ·slopes strongly convex at either side of median sulcus, less convex but 

strongly inclined near cardinal extremities. Sulcus 

broadly V-shaped posteriorly, becoming rather evenly concave anteriorly; anterior margin indented 

strongly by tonguelike extension of sulcus. Lateral 

margins well rounded, curving toward hinge to form 

slightly acute to slightly obtuse angle at cardinal 

extremities. Beak strongly incurved, overhanging 

interarea, which is markedly concave in lateral profile; interarea longitudinally grooved, bearing row of 

fine teeth along anterior margin at either side of triangular delthyri urn. 

Surface ornamented by 3 prominent rounded costae within sulcus and 7 to 11 on each lateral slope, 

separated by subequal, mode·rately deep rounded furrows; costae resemble plications and cause serration 

along line of commissure. Silicification in primary 

types has obliterated microornament. 

Internally, pedicle valve has pair of fairly short 

narrow dental lamellae within umbonal region, 

where shell is moderately thick. Muscle-scar area 

within pedicle valve roughly rhombic in shape. 

Internally, pedicle valve has pair of fairly short 

narrow dental lamellae within umbonal region, 

where shell is moderately thick. Muscle-scar area 

within pedicle valve roughly rhombic in shape. 

Brachial valve less convex than pedicle valve but 

appearing moderately convex in anterior profile. 

Fold moderately elevated, subrounded, marked by 

four rounded costae; lateral slopes with 6 to 10 

costae. 

Dimensions (in mm).-

USNM USNM USNM USNM 

167736 167737 167738 167739 

Length ----- 26 22.5 21 13 

Width ------ 30 24 29.5 17 

Thickness -- 20.5 17 10 

1 Pedicle valve only; depth=12.5 mm. 

Discussion.-Anthracospirifer curvilateralis brutus, although agreeing with Easton's species in 

shape, has fewer ribs than are generally present in 

the Montana form. The holotype has only 3 costae 

in the sulcus and 7 on each lateral slope, as contrasted to the normal 5 in the sulcus and 12 to 16 on 

each lateral slope for typical pedicle valves of A. 

curvilateralis. The range of variation of the two 

forms overlaps slightly, however, at 3 in the fold and 

10 or 11 on each lateral slope. 

This subspecies is based on five specimens from 

two localities in the Moffat Trail, about 30 miles 

apart. The holotype is a nearly complete shell from 

the Moffat Trail section. 

Included tentatively with A. c. brutus are specimens that occur abundantly in a limestone bed in the 

Horseshoe Shale Member immediately below the 

Moffat Trail Limestone Member in the section at 

Hoback Canyon. These actually are intermediate in 

their ribbing between typical A. curvilateralis and 

A. c. brutus,.most of them having 5 costae in the sulcus and 10 o;)l on each lateral slope; they have the 

characteristic microornament of Anthracospirifer. 

A few show splitting of the costae that are near the 

sulcus. This occurs in the one figured on plate 11, 

figure 6, which has t"'.vo costae added by bifurcation 

on one side of the sulcus but not on the other. No 

specimen assigned here to A. c. brutus has more than 

11 costae on each lateral slope. All so assigned occur 

below the base of the Ranchester Limestone Member 

in weste,rn Wyoming. 

Types.-Holotype, USNM 167736; para types, 

USNM 167737-1677 42. 

Occurrence and number of specimens.-Moffat 
BRACHIOPODA OF THE AMSDEN FORMATION D67 

Trail Limestone Member: collections ?75 (1), ?76 

(1), 77 (2), 78 (3 paratypes), 79 (1), 109 (bolotype and paratype), Lincoln County. Horseshoe 

Shale Member: collections 117 (35), 118 (80), 

Teton County. 

Antbracospirifer occiduus (Sadlick) 

Plate 11, figures 24-32 

Spirifer boonensis Swallow, 1860, p. 646. 

Spirifer boonensis Swallow? Girty, 1903, p. 381-383, pl. 6, 

figs. 1-3; Morningstar, 1922, p. 186, 187, pl. 9, figs. 

21-25. 

Spirifer opinws Hall var. occidentalis Girty, 1927, p. 433, 

434, pl. 27, figs. 28-31 [not S. occidentalis Kindle 

1908]. 

Spiri/er oc.cidentalis Girty. Dunbar and Condra, 1932, p. 

322-326, pl. 41, figs. 12-16; Foster, 1942, p. 249, 250, 

text fig. 1; Gehrig, 1958, p. 15, 16, pl. 3, figs. 7-18. 

Spirifer occiduus Sadlick, 1960, p. 1210, 1211, table 1 [new 

name for S. occ1"dentalis Girty, not Kindle]; Spenc·er, 

1967, p. 18-20, figs. no. 3, 9; 12. 

A nthracospirifer occidnus ( Sadlick). Lane, 1963, p. 388; 

1964, p. 781-785; Sturgeon and Hoare, 1968, p. 62, 

pl. 20, figs. 1-7. 

Diagnosis.-Rather large Anthracospirifer, considerably wider than long, greatest width at hinge; 

valves equally convex, sulcus moderately shallow; 

fold high, fairly broad, and well defined. Mature 

pedicle valves ornamented by 25 to 33 costae, 2 or 3 

near sulcus commonly bifurcate. 

Description.-Pedicle valve rather strongly convex in side profile, curvature greatest in umbonal 

region, becoming gradually less toward convex anterior margin; broadly and rather gently arched in 

posterior profile, shallowly indented by median sulcus. Sulcus moderately broad anterio~ly and curving 

dorsally to fit into fold of brachial valve. Anterolateral and lateral margins fairly straight or gently 

convex in outline, commonly steepening toward 

hinge; cardinal extremities narrowly to broadly 

acute. Interarea fairly low; umbo somewhat depressed; beak incurved. 

Surface of pedicle valve sculpture by rounded costae separated by slightly narrower intercostal 

grooves; 5 of these occurring in sulcus, middle one 

commonly larger than others; 12 occurring on each 

flank in type lot; first 2 costae at either side of sulcus are bifurcated near umbo, next 2 primary costae 

typically giving off additional costa on proximal side 

by bifurcation on lateral slopes. Microornament, 

where visible, consists of concentric growth lirae 

crossed by fine longitudinal lirae to form cancellate 

pattern. 

Brachial valve having same convexity as pedicle 

valve except along fold, which is less convex; fold 

broad, elevated, and slightly produced, set off by 

grooves at either side, of strength subequal to intercostal grooves. Costae similar to thoses on pedicle 

valve, 6 normally occurring on fold and 11 on each 

lateral slope. First costa at either side of fold is undivided, but next two primary costae split early on 

lateral slopes. Furrow marking center of fold slightly wider than intercostal grooves at either side. 

Costae on internal mold appearing much sharper 

and elevated than on exterior of shell. Interior of 

brachial valve not clearly shown in type lot. 

Dimensions (in mm).-

USNM USN.ll 1 118717A 2 118717B 

Length ------------------ 28 30 

Maximum width _________ ·i 44 48 

Thickness --------------- "19 

Depth (one valve) ______ _ 13 

1 USNM 118717A is lectotype retaining most of both valves. 2 USNM 11877B is pedicle valve paralectotype. a USNM 118717C is brachial valve paralectotype. 4 Twice the half length. 

"Slightly less than actual thickness because of crushing. 

USNM 

at18717C 

23.5 

42 

9 

Discussion.-The description above is based on 

Girty's original specimens from the Wells Formation in the Crow Creek quadrangle, Idaho (USGS 

loc. 32-PC, sec. 35, T. 9 S., R. 45 E.). The most complete specimen figured by Girty (1927, pl. 27, figs. 

28, 29) was selected by Sadlick (1960, p. 1210) as 

the lectotype and is figured together with two paralectotypes on plate 11, figures 24-30. Four additional unfigured paralectotypes are in the National 

Museum colection (USNM 167743). A hypotype 

from Hoback Canyon figured on plate 11, figures 31, 

32, shows the dental ridges flanking the delthyrium 

on either side and extending forward as short teeth 

that engage with the brachial valve; also the deeply 

impressed lenticular area in which the adductor muscles are attached. 

Lane (1964) has discussed the variation in costation that is present in this and related species. Normally 5 or 7 costae occur in the sulcus, 6 or 8 on the 

fold, and 9 to 16 on each lateral slope. Actually, mature specimens of A. occiduus with more than 13 and 

less than 11 costae on each lateral slope are relatively rare. The subacute cross section of the costae on 

internal molds is one of the peculiarities of this species. A tendency for some of the costae to bifurcate 

is also characteristic, at least so far as western 

specimens are concerned. In specimens from the 

American midcontinent, such bifurcation is very 

rare. It might in fact, be possible to recognize a 

western and eastern subspecies of A. occiduus or two 

distinct species based on this difference, but pending 

further study both forms are included in the same 

taxon. 

Compar-isons and afjinities.-A. occiduus differs 

from A. currvilateralis (Easton) in its relatively 
D68 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

shorter and more transverse shell (the greatest 

width occurring invariably at the hinge) and its 

higher, more prominent fold. The broad gentle arching of the pedicle valve of A. occiduus, viewed from 

the posterior, contrasts with the convex and sloping 

flanks of A. curvilateralis. In the western form of A. 

occiduus the tendency of the costae near the sulcus 

to split also differs from A. curvilateralis, in which 

bifurcation of the costae is a rarity. 

A. matheri (Dunbar and Condra) is a closely related species having approximately the same number of costae on each lateral slope as A. occiduus, 

some of which, like those on the fold and sulcus, tend 

to bifurcate. Examination of topotypes from the 

Brentwood Limestone Member of the Bloyd Shale of 

northwest Arkansas shows that it is a somewhat 

smaller species than A. occiduus, having 5 to 9 plicae 

in the sulcus, 6 to 10 on the fold, and 10 to 13 on each 

lateral slope in fully mature shells. Bifurcation of 

the plicae in A. matheri tends to be irregular. Commonly, an extra plica will develop on one slope of 

the fold and sulcus but not on the other, resulting in 

an odd number of plicae on the fold and an even 

number in the sulcus. Also, a plica may bifurcate on 

one lateral slope and a different plica on the other 

lateral slope in the same valve. No specimens were 

observed showing bifurcation in the same direction 

of two adjacent plicae, as is common in A. occiduus. 

A. opimus (Hall) is a narrower species having 

subparallel lateral margins that give it a subrectangular shape. It has fewer costae and costellae 

than A. occidutls, normally four costae occurring on 

the fold. 

Although A. occiduus was commonly identified as 

A. rockymontanus (Marcou) by 19th century paleontologists, little similarity exists between the small 

subcircular shell of the Rocky Mountains species, as 

established by the designation by Girty (1903, p. 

384) of a lectotype for Marcou's species, and the 

moderately large transverse shell of A. occiduus. 

Types.-Lectotype, USNM 118717 A; paralectotypes, USNM 118717B, C, 1677 43 (seven paratypes 

in all) ; hypotype, 1677 44. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 1 (1), 5 (2), Carbon 

County. Ranchester Limestone Member: collections 

6 (21), 14 (3), ?15 (3), Carbon County; 83 (3), 

84 (3), ?89 (3), 99 (1), 100 (2), ?101 (1), Lincoln 

County; 133 (1), Sublette County; 131 (3), ?140 

(1), 141 (1), Teton County. 

Anthracospir:ifer aff. A. occiduus (Sadlick), form A 

Plate 11, figures 19, 20 

Spirifer shoshonensis Branson and Greger. Easton [part], 

1962, p. 70, pl. 9, figs. 22a, b [not figs. 21a-c]. 

Partly crushed transverse shells of Anthracospirifer in reddish-gray shale of latest Mississippian age 

at the north end of the Teton Range are much like 

A. occiduus in some respects, but they also have 

several characters that differentiate them from 

typical A. occiduus. Mature examples of these spirifers reach 50 mm in width and more than 26 mm in 

length. Because of crushing, the overall thickness of 

these shells is not known, but some of the pedicle 

valves have a general shape similar to that of A. 

occiduus. 

Pedicle valves are commonly alate, some with very 

acute cardinal extremities, the greatest width of 

the shell invariably at the hinge. The beak is incurved but does not overhang the interarea markedly. Viewed posteriorly, the pedicle valve has 

rather low convexity and the median sulcus is shallow. Similarly, in the brachial valve the fold is low 

and moderately broad; plications are low, subrounded, with narrower rounded grooves between. 

Typically, 3 or 5 plications occur in the sulcus, 

4 or 6 in the fold, and 14, rarely 15, on each lateral 

slope. As in A. occiduus, the three primary plications at either side of the sulcus tend to split into 

two. The first, which borders the sulcus, splits near 

the beak, and the next two give off a weaker plication admedially, a few millimeters forward on the 

valve. Microornament consists of fine radial lirae 

crossed by concentric striae and lamellae of growth. 

The Berry Creek shells resemble A. occiduus in 

the moderately low convexity of pedicle valves and 

in the pattern of splitting of the major plications 

on the lateral slopes. They differ from that species, 

however, in the very shallow median sulcus of the 

pedicle valve and lower fold of the brachial valve 

and in having a couple more plications on each 

lateral slope. Nor are the plications subangular 

internally and on the inside of the shell as is typical 

in A. occiduus. In the absence of complete or well 

enough preserved specimens for a thorough comparison with A. occiduus and related species, the 

problem whether these shells ( 1) should be included 

within A. occiduus s.l., (2) should constitute a subspecies of A. occiduus, or (3) are a distinct species 

cannot be resolved here. 

A unique Anthracospirifer from the Cameron 

Creek in Fergus County, Mont. was figured by 

Easton (1962 1 p. 70, pl. 9, figs. 22a, b) as Spirifer 

shoshonensis Branson and Greger. This specimen 

(USNM 118809) is identical in shape, shallow sulcus, splitting pattern, and number of plications with 

the Berry Creek shells. Although present in beds 

now thought to be Pennsylvanian in age (Maughan 

and Roberts, 1967, pl. 4), its stratigraphic position 
BRACHIOPODA OF THE AMSDEN FORMATION D69 

is near the Mississippian-Pennsylvanian boundary. 

The Berry Creek specimens are likewise near this 

boundary, as latest Mississippian Zone 19 Foraminifera have been identified by Mamet (1975) in 

the same beds. 

Anthracospirifer aff. A. occiduus, form A, may, 

therefore, be a distinct form that precedes typical 

A. occiduus in stratigraphic sequence in this part 

of the Rocky Mountain region. On the other hand, 

as all our specimens of A. aff. A. occiduus form A, 

are from shale beds and all our specimens of typical 

A. occiduus are from limestone, chert, and calcareous siltstone beds, the possibility of facies control 

of the observed differences cannot now be eliminated. 

Figured specimens.-VSNM 167745. 

Occurrence and number of speci-mens.-Horseshoe 

Shale Member: collections 26a (1), Fremont 

County; 149 (7), 150 (5), ?151 (2), 152 (10), 153 

(18), 155 (1), 156 (5), 157 (5), 158 (2), Teton 

County. 

Anthracospirifer aff. A. occiduus (Sadlick), form B 

Plate 11, figures 21-23 

Anthracospirifer in two collections from the west 

slope of the Teton Range are related to A. occiduus 

but differ from it in shape in the direction of A. 

increbescens (Hall). The outline of the pedicle 

valve is less transverse than in typical A. occiduus, 

the lateral margins more rounded, and the cardinal extremities terminatiing in short points. In 

posterior view the shell is rather flat in the middle, 

the sulcus appearing as a shallow rounded depression at the center. Beyond the nearly flat area the 

lateral slopes are strongly convex, then become 

concave near the cardinal extremities. The beak is 

fairly low and incurved. 

The figured specimen is typical. It has 5 costae 

in the sulcus and 14 on each lateral slope. Primary 

costae at either side of the sulcus are bifurcate as 

in A. occiduus. Brachial valves are scarce. On them 

the fold is mode,rately elevated and bears six costae. 

Anthracospir;·ifer aff. A. occ1:duus, form B, is 

narrower and its pedicle valve is more convex 

transversely than form A. Like form A, these shells 

are in rocks of probable latest Mississippian age, 

but the possibility of these two collections coming 

from rocks of Early Pennsylvanian age cannot be 

entirely eliminated. 

Figured specimen.-USNM 1677 46. 

Occurrence and number of specinwns.-Ranchester Limestone Member: collections 146 (85) and 

148 (12), Teton County. 

Anthracospirifer rawlinsensis n. sp. 

Plate 11, figures 13-18 

Diagnosis.-Medium-sized spirifer; length and 

width subequal, greatest width at or near hinge 

line; cardinal extremities subrectangular; sulcus 

broadly V-shaped in cross section. Mature pedicle 

valves ornamented by 37 to 39 costae. 

Description.-Pedicle valve strongly convex, 

greatest convexity posterior to middle) transversely 

suboval to subrohombic in outline, width usually 

slightly greater than length; lateral slopes fairly 

steep ; margin rounding toward hinge and meeting 

it approximately at right angles. Median sulcus 

broad, equal to about one-fourth width of shell at 

midlength, moderately deep to fairly shallow, broadly V-shaped posteriorly, becoming concave anteriorly and extending forward and upward beyond 

plane of commissure in prominent tonguelike deflection of margin that fits into fold of brachial 

valve. Umbo incurved and overhanging interarea; 

umbonal slopes moderately steep ; umbonal angle 

about 110°. Interarea moderately high, concave in 

lateral profile. Shell exceeds 2 mm in thickness 

over much of umbonal region. 

Surface sculpture in pedicle valve consisting of 

7 low rounded costae in sulcus and 15 or 16 on each 

lateral slope; costae separated by narrower shallow 

rounded furrows. Central costa in sulcus begins at 

tip of umbo and three at either side split off at 

regular intervals from major costa that delimits 

sulcus at either side. Bifurcation generally affects 

three primary costae at either side of sulcus and 

in rare instances, takes place randomly. Microornament consists of moderately strong growth 

lamellae crossed by faint capillae (seen only in one 

small patch near anterior margin of holotype). 

Interior of pedicle valve without well-developed 

dental lamellae. Muscle scars occupying elongate 

rhombic area within umbonal region bordered by 

pair of curved raised ridges that unites anteriorly 

in single broad ridge along inside of sulcus. Interior 

of lateral slopes with a few longitudinal ridges 

separated by wider concave interspaces. 

Brachial valve less convex than pedicle valve. 

Fold beginning at beak, moderately low and rounded, 

set off from lateral slopes by furrows that are wide;r 

than intercostal furrows; fold becoming higher 

anteriorly but not necessarily better demarcated 

because inclination of later slopes increases to degree that break in slope at base of fold is slight. 

Ornamentation of costae and furrows similar to 

those in pedicle valve. 
D70 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Dimensions (in mm) .-

Length _____ _ 

Width -------

Depth -------

Thickness ----

Holotype 1 

USNM 

167747 

32 

36 

15 

l'aratype 

USNM 

167749 

2 22 

28.5 

8 

Pa-ra type USNM 

167750 

19 

23 

8 

Para type USNM 

167753 

~ 26 

22.5 

17.5 

1 First three are pedicle valves; last is articulated shell lacking beak area. 

2 Estimated. 

Discussion.-Anthracospirifer rawlinsensis n. sp. 

is represented by six pedicle valves and one fragment 

of a brachial valve from one U.S. Geological Survey 

collection and a narrow articulated specimen lacking 

the beak and part of the fold, from another, both 

from localities in the Rawlins hills. A mature pedicle valve has been selected as the holotype. 

The identifying characters of this species are its 

relatively narrow shape, broadly V-shaped median 

sulcu~ in the pedicle valve, and the relatively large 

number of costae that ornament both valves. These 

characters enable it to be separated rather easily 

from other Amsden spiriferoid species. 

This species resembles Spirifer adonis Bell from 

the Windsor Series (Subzone C) of Nova Scotia in 

its general shape and similar costation. It differs 

from that species in having a sliwhtly less convex 

pedicle valve, less incurved beak, higher interarea, 

longer hinge line and subangular rather than rounded cardinal extremities. The beds containing S. 

adonis are late Visean (=early Chesterian) in age, 

according to a study of their small Foraminifera by 

Mamet (1970). 

Approximately the same number of costae occurs, 

however, in another Wyoming species, A.nthracospirifer shoshonensis (Branson and Greger), from 

the Bull Ridge Member of the Madison Limestone, of 

early Late Mississippian age. Pedicle valves in the 

type lot of that species, with which our specimens of 

A. rawlinensis have been directly compared, bear 33 

to 41 costae. A. shoshonensis can be distinguished 

from A. 'rawlinsensis by its more transverse shell, its 

narrow and very shallow median sulcus, normally 

containing five costae, the subangularity of its costae, and a strong tendency for them to split somewhat randomly, producing odd and unbalanced combinations locally in some specimens, such as six 

costae in the sulcus and seven on the fold. In one 

of the primary types of A. shoshonensis the median 

costa in the sulcus is bifurcated. In _4. rawlinsensis, 

splitting of the plications is more regular and largely confined to those on the lateral slopes near the 

sulcus and fold. 

Types.-Holotype, USNM 167747; paratypes, 

USNM 167748-167753. 

Occurrence and number· of specimens.-Horseshoe 

Shale Member : collections 3 (holotype and five paratypes), 4 (paratype), Carbon County. 

Anthracospirifer shawi shawi n. subsp. 

Plate 12, figures 25, 29-33, 37-42 

Spi1·ijer pellaensis Weller. Branson and Gr.eger, 1918 [part], 

p. 317, pl. 18, fig. 7 [not figs. 8, 9 J. 

Diagnosis.-Small, moderately transverse Anthracospirife'r, having cardinal extremities acute or rarely tending toward subrectangular; sulcus moderately deep and fold high and narrow. Adult shells normally having 17 to 21 prominent rounded costae on 

pedicle valve, separated by rather deep furrows. 

Description.-Shell wider than long, moderately 

alate, greatest width at hinge; cardinal extremities 

typically acute, commonly extended as short points, 

but approaching rectangular in some specimens. 

Pedicle valve moderately to strongly convex in side 

profile, greatest curvature near beak and decreasing 

slightly anteriorly; umbo not strongly incurved; 

beak suberect to erect. Valve broadly arched in posterior profile, indented by median sulcus that begins 

at umbo, V-sihaped in cross section posteriorly, more 

evenly concave anteriorly, extended as flat tongue to 

fit into fold of brachial valve. Lateral slopes rounding rather strongly toward cardinal extremities; 

lateral margins becoming less rounded and slanting 

posterolaterally toward cardinal extremities. Interarea low to moderately high, gently concave in side 

profile, meeting plane of commissure at angle of approximately 150°, more highly convex near beak; 

delthyrium wider than high, occupying slightly less 

than one-fifth of width of hinge line. 

Surface sculpture on pedicle valve consisting 

typically of three costae within sulcus, four on fold, 

and seven to nine on each lateral slope in adult shells. 

Costae are well rounded, rather broad, and separated 

by deep and narrow intercostal furrows; typically, 

they do not bifurcate on lateral slopes. Within initial 

part of sulcus, a median costa is the only one present; at distance of 6 to 7 mm from beak, two more 

split off from costae delimiting each side of sulcus, in 

manner typical of Anth'racosph·ifer and related 

genera. 

Brachial valve nearly as convex as pedicle valve, 

alate. Fold beginning at beak, narrow and rather 

low, becoming rather highly elevated in anterior 

two-thirds of valve, set off from lateral slopes by 

furrows that are no wider than intercostal furrows. 

Ornamentation of costae and furrows similar to 

those in pedicle valve. 

Dimensions.-The only two undistorted specimens 

available, the holotype and a paratype (USNM 
BRACHIOPODA OF THE AMSDEN FORMATION D71 

167757), measure respectively (in mm) :length 17.2, 

17.0, maximum width 23.8, 24.5; and thickness (both 

valves) 13.7, 13.0. 

Discussion.-This species is based mainly on 

shells from the general vicinity of the Little Popo 

Agie River, including Cherry Creek. The holotype is 

the smallest of three specimens described and 

figured by Branson and Greger (1918, p. 137, pl. 18, 

figs. 7-9) as Spirifer pellaensis Weller. It is a calcareous specimen and, as has been pointed out earlier in this report, the calcareous brachiopod shells at 

Cherry Creek and its vicinity appear to have come 

from the lower fossiliferous zone ( Carlinia amsdeniana Subzone). The other two specimens figured by 

Branson and Greger are silicified and are regarded 

as belonging in a more advanced subspecies of A. 

shawi, one of them being designated as the type 

specimen of the subspecies. 

Designated paratypes include two specimens coll:cted by Keyte at Enterprise Ditch (colin. A) and 

six others from an undisclosed locality in Fremont 

County (colin. F), as well as the specimen illustrated on plate 12, figure 25, from the section at 

Darwin Peak, Teton County. This species is named 

for Alan B. Shaw in recognition of his work on the 

Paleozoic rocks of Wyoming. 

All the specimens that have the characters of 

typical A. shawi shawi are calcareous shells; only 

~wo calcareous specimens, from an unknown locality 

In Fremont County, are assigned to the subspecies 

A. s. exoletus. This would seem to indicate that A. 

shawi shawi is restricted to the Carlinia atnsdeniana 

Subzone in the type region and that the more advanced subspecies, if present at all in this subzone . ' Is rare. 

This subspecies is fairly easily distinguished from 

A. welleri welleri, the more common Anthracospirifer in the same subzone, which differs in having a 

subcircular shell with rounded cardinal extremities, 

a lower fold and shallower sulcus, and narrower and 

more numerous costae on the lateral slopes. 

Types.-Holotype, 2651B; paratypes, USNM 

163711, 163712, 167757, 167758 (nine paratypes in 

all). 

Occurrence and nu1nber of specimens.-Horseshoe 

Shale Member: collections 26b (1), 36b (1), 43 (5), 

45 (10), 49 (16), A (2), E (2), F (6), Fremont 

County; 137 ( 7) , 138 ( 1) , Teton County. 

Antbracospirifer shawi exoletus n. subsp. 

Plate 12, figures 26-28, 34--36, 43-47 

Spirifer pellaensis Weller. Branson and Greger, 1918 [part], 

p. 317, pl. 18, figs. 8, 9 [not fig. 7]. 

Spirifer opimus Hall. Burk, 1954 [part], p. 11, pl. 1, figs. 

16-18, 20-22 [not fig. 19]. 

Spirifer sp. Burk, 1954, p. 11. 

Diagnosis.-Like Anthracospirifer shawi shawi, 

but somewhat larger and having more numerous costae in sulcus and on lateral slopes, typically 23 to 27 

on each valve; some costae (rarely) tend to 

bifurcate. 

Description.-Shell medium- sized, moderately 

transverse and alate. Both valves rather strongly 

convex in side profile. Sulcus in pedicle valve moderately deep; fold in brachial valve high and fairly 

narrow. 

Surface sculpture on pedicle valve consisting of 5 

costae (rarely 3) in sulcus, 6 costae (rarely 4) on 

fold, and 10 to 11 on lateral slopes. Costae less broadly rounded than in typical form; intercostal furrows 

rounded, subequal in width to costae. Splitting of 

costae occurs on some shells, most commonly involving third costa from sulcus by addition of another 

costa on proximal side. In sulcus, second and third 

costae split off 4 to 5 mm anterior to tip of umbo; 

next pair is added 10 to 12 mm further forward. 

Fine radial lirae) typical of the microornament of 

Anthracospirifer is visible on some specimens (see 

pl. 12, fig. 43). 

Discussion.-Anthracospirifer shawi exoletus is 

the common spirifer of the Composita poposiensis 

Subzone in the Wind River Range. Brachiopods in 

this subzone are generally silicified. Although this 

subspecies is more common than the typical form, 

unbroken and undistorted specimens are not known. 

The holotype is the specimen, 37 mm wide, figured 

as Spirifer pellaensis by Branson and Greger (1918) 

on plate 18, figure 9 ; it is refigured here on plate 12, 

figure 35. It is partly crushed and distorted so as to 

overemphasize the acuteness of the cardinal extremities, but is the most complete specimen available. A 

paratype of this subspecies, from Cherry Creek, also 

figured by Branson and Greger (1918, pl. 18, fig. 8), 

is shown here on plate 12, figure 34. Other paratypes, 

some of which are also figured in this report, include 

two calcareous USNM shells collected by Keyte 

(colin. F) , four silicified shells from Cherry Creek, 

figured by Burk (1954) as Spirifer opimus (colin. 

35), and nine additional specimens from a collection 

made by Hen best at Little Popo Agie Canyon (colin. 

38). 

Direct comparison of the shells figured by Burk 

(1954) as "Spirifer opimus Hall" with those figured 

by Branson and Greger (1918) as "S. pellaensis 

Weller" shows that they belong in the same species, 

with a single exception-the one figured by Burk on 

his plate 1, figure 19, is a specimen of Anthracospiri-
D72 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

fer welleri welleri (Branson and Greger). Shaw and 

Bell (1955, p. 335, fig. 1) followed Burk in identifying the spirifer of the upper zone ( C01nposita poposiensis Subzone of this report) as S. opimns Hall, 

but Shaw (1955, p. 60), discussing the fossils of the 

upper zone, referred to them as the Spirifer "opimus" fauna. He cited a letter in which Sadlick suggested that this might be a species related to A. 

leidyi (Norwood and Pratten) and a precursor of 

true A. opimus and said that he agreed with t:his 

opinion. Sadlick (1955, p. 56) also stated the same 

opinion. 

Anthracospirifer opimus (Hall) was described 

originally from the Coal Measures of Ohio, Maryland, and Iowa and differs from A. shawi exoletus 

in its constant subrectangular shape, broader and 

lower fold, and fewer costae (it normally has three 

in the sulcus, four on the fold, and eight on each 

lateral slope). 

Anthracospirifer pellaensis Weller differs from 

A. shawi exoletus in its narrower and more numerous costae, slightly lower interarea, and prominent 

concentric lamellae along the anterior slopes in both 

valves. The Iowa species is more variable in shape 

than A. shawi and includes decidedly alate shells 

with an many as 18 costae on each lateral slope, as 

well as narrower forms with fewer costae. No more 

than 11 costae on each lateral slope occur in our 

Wyoming shells. 

Types.-Holotype, UM 2651A; para types, UM 

3533, UW IT-202 to 205, inclusive, USNM 167754-

167756, 174071. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 19 (1), 26a (7), 26b (11), 

29 (3), 32 (4), ?34 (3), 35 (85), 36a (1), 36b (1), 

36e (23), 38 ( 41), ?48 (1), F (2), Fremont County. 

Ranchester Limestone Member: collection 82 (2), 

Lincoln County. 

Anthracospirifer welleri welleri (Branson and Greger) 

Plate 12, figures 1-24 

Spirij'e1· welleri Branson and Greger, 1918, p. 317, 318, pL 

18, figs. 10, 11, 18; G. Branson, 1937, p. 652. 

Rhip1'dmnella gregeri C. Branson 1937 [part], p. 655, pl. 89, 

figs. 16, 17. 

Spirifer opimus Hall. Burk [part.], 1954, p. 11, pl. 1, fig. 19 

[not figs. 16-18, 20-22]. 

Not Spirifer welleTi Branson and Grege1·. Ea~.ton, 1962, p. 70, 

pl. 9, fig. 23. 

Diagnosis.-Small, moderately tumid Anthracospirifer; length and width subequal; hinge short; 

cardinal extremities rounded to obtusely subangular; sulcus shallow and fold low; typically with 21 

to 27 narrow costae on pedicle valve. 

Descr1:ption.-Pedicle valve subcircular in outline, 

greatest width at or near midlength; lateral margins rounding toward hinge and meeting it at ob~ 

tuse angle; valve fairly deep, strongly convex both 

in side and posterior profiles, greatest convexity 

posterior to middle, opposite hinge. Beak rather 

strongly incurved; interarea concave poste!riorly, 

nearly flat anteriorly, poorly delimited posterolaterally where umbonal slopes curve to meet it, height 

of interarea equal to approximately one-third its 

length ; pierced by triangular delthyri urn, base of 

which occupies nearly one-third length of hinge-line. 

Sulcus shallow, fairly broad, gently concave in cross 

section, begins at umbo and extends to anterior 

margin where it produces shallow deflection. Surface 

of valve marked by low rounded to subangular costae separated by subequal rounded furrows; normally 3 costae occurring in sulcus and 9 to 11, rarely 

12, on each lateral slope. Interior of pedicle valve 

micro-ornament of Anthracospir1:fe1'. As pointed out 

muscle-scar field narrow, elongate. 

Brachial valve transversely suboval in plan, less 

convex than pedicle valve. Median fold fairly low, 

not elevated at all at beak, set off from rest of valve 

by bordering furrow at either side that is slightly 

wider than those between costae. Fold normally 

bearing 4 costae; 8 to 11 occurring on lateral slopes 

as in pedicle valve. Micro-ornament in both valves 

consists of fine radial lirae crossed by fine incremental striae and weak growth lamellae. 

Dimens1:ons (in mm).-

Para1ectotype Lectoty]Je Paralectotype 

Height --------- 16.5 15.5 12.5 

Width ---------- 18.0 16.7 16.5 

Thickness ------ 11.0 11.6 9.0 

Discuss1:on.-Three syntypes in the collection of 

the University of Missouri (UM 3532), upon which 

Branson and Greger (1918, p. 317, pl. 18, figs. 10, 

11, 16) based their description and illustrations of 

the typical form of this species., are refigured in this 

report (pl. 12, figs. 1-12, 14-19). The specimen 

figured by Branson and Greger in their plate 18, 

figure 16, is hereby designated the lectotype. It is 

the most typical of the three shells. The other two 

specimens constitute the paralectotypes, of which 

the one figured by Branson and Greger on their plate 

18, figure 10, is slightly better preserved than the 

lectotype and preserves the microornament. This 

specimen is, however, a bilaterally asymmetrical 

pathologic specimen. The interarea is considerably 

wider on one side than on the other; it has 12 costae 

on one lateral slope of the pedicle valve and 10 on 

the other. The third specimen is slightly more transverse and less tumid than is normal in this species. 
BRACHIOPODA OF THE AMSDEN FORMATION D73 

The measurements of all three specimens are given 

in the table above. 

Specimens from the Popo Agie River in the early 

neanic growth stage were described and figured by 

C. C. Branson as "Rhipidomella gregeri n. sp." 

Radial striations and closely spaced growth lines described by Branson as marking the surface of shells 

at an average length of 0.8 mm constitute the typical 

micro-ornament of Anthracospirifer. As pointed out 

in Branson's description, the fold and sulcus are 

just beginning to appear in these specimens. 

The holotype and paratype of R. gregeri, figured 

in Branson's paper, have unfortunately suffered the 

ravages of time, one valve missing and the other 

apparently damaged, but another "cotype" (UM 

6593) and nine "metatypes" (UM 6613) show the 

characters at this stage very well. Another shell, 

also in the University of Missouri collection, labeled 

as a "cotype" of R. gTegeri (UM 6585), is a tiny 

terebratuloid having a finely punctate smooth shell. 

The central Montana records of this species 

(Easton, 1962, p. 70, pl. 9, fig. 23), some of them 

from beds now believed to be Pennsylvanian in age 

(Maughan and Roberts, 1967, p. B20-B23), are not 

considered valid. Easton, in fact, questioned two of 

his three identifications of Spirifer welleri. The 

small fragmental pedicle valve from the Heath Formation (USGS colin. 13414-PC) is not complete 

enough to be identified. Easton's figured specimen 

from the Alaska Bench Limestone (USGS colin. 

13404-PC) resembles A. welleri, but its cardinal extremities have been broken off, and the shell is less 

tumid than is typical for A. welle1·i; like the last, it 

cannot be identified with certainty as to species. Two 

other specimens from the Alaska Bench Limestone 

(USGS colin. 13404-PC) are transverse, alate shells 

with acute cardinal extremities and should be referred to A. occiduus (Sadlick). 

Compari.c:wns and affinities.-AnthracospirifeT 

welleTi is distinguished by its tumid shape, narrow 

interarea, rounded to obtusely subangular cardinal 

extremities, and rather small size. All specimens 

from Cherry Creek, the type locality of this species, 

have only three plications in the sulcus in the pedicle valve. 

AnthracospirifeT bTeckenTidgensis (Weller) somewhat resembles this species in having a similar shell, 

subcircular in outline, bearing a short interarea and 

obtusely subangular cardinal extremities. Examination of a large suite of specimens from a shale bed 

in the Gasper Oolite in Breckenridge County, Ky., in 

the U.S. Geological Survey collection, indicates that 

shells similar to Weller's types intergrade with 

somewhat wider forms, including even somewhat 

alate specimens, all apparently belonging to the 

same population. Although related to A. welleTi in 

a general way, A. breckenTidgensis differs (besides 

intergrading with wider shells having acute cardinal 

extremities) in having lower and generally fewer 

rounded plications (of which normally seven to nine 

occur on e~ach lateral slope), a more elevated and 

slightly narrower fold in the brachial valve, a steeper interarea in the pedicle valve, and more prominent 

growth lamellae anteriorly on both valves. 

Intergradation between A. welleri and A. shawi 

has not been noted. A. shawi differs in having a more 

transverse shell with acute or subacute cardinal extremitie~s, a more elevated and slightly narrower fold 

in the brachial valve, and generally wider and more 

prominent costae. 

Types.-Lectotype and two paralectotypes, UM 

3532; hypotype, UW IT -201. Holotype of Rhipidomella gTegeTi C. Branson, UM 6586; paratypes UM 

6593, 6602, 6613. 

OccuTrence and number of specimens.-Horseshoe 

Shale Member: collections 21 (6), 22 (14), 26b 

(70), 27 (3), 28 (10), 29 (3), 30 (9), 31 (9), 36a 

( 38 +fragments) , 36b (lectotype and two paralectotypes of A. welleTi), 36d (holotype and 11 paratypes 

of R. gTegeTi), 39 (4), B (8), E (1), Fremont 

County. 

Anthracospirifer welleri lincolnensis n. subsp. 

Plate 13, figures 1-7 

D,iagnosis.-Moderate1y narrow medium-sized 

AnthracospirifeT normally having 29 or 31 costae on 

pedicle valve, some of them increasing by bifurcation; cardinal extremities subrectangular to submucronate; umbonal region solid, filled with secondary 

calcareous material 

DescTiption.-Shell moderately tumid, both valves 

equally convex, transverse to elongate oval in outline, 

submucronate; greatest width at or near hinge line; 

lateral margins fairly straight to sigmoidal, greatest 

convexity near beak, which is moderately incurved, 

and lessening anteriorly. Interarea rather low to 

moderately high, concave in profile view. Median sulcus well defined, concave in cross section, beginning 

at umbo and extending to anterior margin but shallowing anteriorly, forming short anteriorly produced 

lingua that protrudes into fold of brachial valve. 

Surface of valve bearing rounded costae separated 

by slightly narrow intercostal furrows; normally 5 

costae are present within sulcus and 12 or 13 on each 

lateral slope. Costae on inner part of lateral slopes 

tend to bifurcate, those bordering sulcus dividing 
D74 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

near beak. or near middle of shell toward outer side ; 

third and fourth primary costae commonly dividing 

on inner side. Shell rather thick; interior of pedicle 

valve filled with secondary calcareous deposit, particularly in umbonal part surrounding short narrow 

dental plates. 

Brachial valve about as deep as pedicle valve; 

greatest convexity approximately in middle of valve 

in both lateral and transverse profiles. Fold bordered 

by prominent furrows. Costae like those in pedicle 

valve, having normally 6 on fold and 11 or 12 on each 

lateral slope, the one at either side of fold normally 

bifurcated. Brachial valve interior not observed. 

Dimensions.-Holotype measures (in mm); 

length, 18.5; width near middle of shell, 21; width 

at hinge, 20; and thickness (both valves) 13.5. 

Gerontic specimens commonly are longer than wide, 

a large pedicle valve from the same locality as the 

holotype measuring (in mm): length, 28; width near 

middle, 24; width at hinge, 20; and depth 12. 

Discussion.-Despite the relative abundance of 

the material, none of the shells is well preserved. 

The holotype is a typical complete, but somewhat 

eroded shelL At its type locality in the Salt River 

Range, A. welle,ri lincolnensis occurs in the Ranchester Limestone Member in association with rare specimens of a moderately alate anthracospirifer referred to A. shawi exoletus. 

At Berry Creek in the Teton Range, A. w. lincolnensis occurs in limestone lenses in reddish-gray shale 

of the Horseshoe Shale Member. Surfaces of some of 

the sheUs are fairly well preserved and show the 

typical micro-ornament of intersecting radial and 

concentric lirations. The costae are well rounded, the 

intercostal furrows decidedly narrow, and the tendency toward bifurcation of the costae less than at 

the type locality. No example of this species has been 

found in the shale beds, which are crowded with 

shells of Anthracospirifer aff. A. occiduus (Sadlick), 

form A. This facies control of the anthracospirifers 

is striking. 

Comparisons and affinities.-This species is somewhat variable, both in shape and sculpture. Specimens have been observed having three, five, or seven 

costae in the sulcus, but the two extremes are rare. 

Some small specimens having three costae in the sulcus also have rounded cardinal extremities and thus 

do not differ materially from A. welleri welleri. This 

is believed to indicate a derivation of A. w. lincolnensis from A. w. welleri. For this reason it is considered a subspecies of A. welleri, rather than a distinct species. 

Typical A. w. lincolnensis differs from A. w. wel-

' leri in having suibrectangula.r to submucronate cardinal extremities in the adult shell, in generally having 

two more costae in the sulcus, on the fold, and on 

each lateral slope than are found in A. w. welleri, 

and in the bifurcation of certain of the costae. Although it resembles A. w. welleri somewhat in its 

narrow shape, A. w. lincolnensis develops a pattern 

of costation somewhat like that of A. occiduus. 

A. birdspringensis Lane, the type species of Anthr·acospirifer, is similar in some respects to A. 

welleri lincolnensis. The maximum number of its 

costae is the same as the normal number of costae in 

A. w. lincolnensis, and the costae bifurcate in roughly the same manner. The normal number of costae in 

A. bir·dspringensis is less than in A. w. lincolnensis 

and may be as few as three in the sulcus and seven 

on each lateral slope. The shell of A. birdspringensis 

is more transverse and the costae narrower and 

intercostal furrows wider than in A. w. lincolnensis. 

Types.-Holotype, USNM 167759; paratypes, 

USNM 168459, 174031. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 149 (36), 153 (4), 154 

(50), Teton County. Ranchester Limestone Member: 

collections 82 (65), 96 (3), 97 (11), 98 (2), Lincoln County. 

Genus BRACHYTHYRINA Fredericks, 1929 

Bracbytbyrina washakiensis n. sp. 

Plate 13, figures 8-13 

Diagnosis.--Medium-sized transverse spiriferoid 

resembling Anthracospirifer increbescens (Hall) in 

outline, but having costae of very low convexity 

separated by narrow grooves, as in Brachythyris, of 

wh~ch 35 to 37 occur on pedicle valve. Micro-ornament of fine concentric lirae without · radial elements. 

Description.-Pedicle valve wider than long, 

greatest width along hinge; cardinal extremities 

generally extended as sharp points; moderately convex in side view, greatest convexity near posterior 

end, becoming slightly less convex near anterior 

end; beak moderately incurved; convexity moderate 

to low in posterior view. Interarea wide, extending 

to extremities of hinge, strongly concave posteriorly 

to nearly flat anteriorly, longitudinally grooved, 

minutely toothed along anterior edge; triangular 

delthyrium slightly wider than high, each side bordered internally by shallow dental ridge terminating 

in hinge tooth. Median sulcus beginning 2 or 3 1nm 

in front of beak and extending to anterior 1nargin, 

broadly V -shaped in middle of valve, becoming 

gently concave toward anterior margin, its lateral 

boundaries poorly delimited. 
BRACHIOPODA OF THE AMSDEN FORMATION D75 

Surface sculpture consisting of low gently rounded 

costae separated by very narrow grooves. Five costae in sulcus on all pedicle valves of type lot, middle 

one either narrower or slightly wider than strong 

adjacent pair ; outer pair always narrow, weakly 

split from broad costa at either side of sulcus. Costae 

on lateral slopes become lower, narrower, and 

weaker toward cardinal extremities, where they 

are difficult to distinguish; 15 or 16 is usual number on lateral slopes. 

Brachial valve less convex than pedicle one, its 

greatest convexity slightly posterior to middle of 

valve. Fold not clearly defined at beak, but begins 

2 to 3 mm in front of it, extend5ng to anterior Inargin; fold low, moderately broad, and not n1arkedly 

set off by flanking grooves. Surface ornamentation 

similar to that of pedicle valve; six costae occur on 

fold. 

Di1nens'ions.-Two pedicle valves (holotype and 

paratype) : length 25 (estimated) and 20, width 

37.5 and 35 (estimated), depth 10.0 and 9.5 1nm, 

respectively. 

Discussion.-This species is based on five pedicle 

valves and one brachial valve, all of them incomeplete. These have the surface partly silicified; they 

have the main characters of the species, and the species is distinctive enough to be rather easily identified and not readily confused with any other spiriferoid in the Amsden of VVyoming. Microornament 

can be seen on some of the surfaces and also in a 

small fragment of external mold :fron1 one of the 

specimens. 

Bifurcation of the costae is rare on the lateral 

slopes in most of these specimens and is difficult to 

see because of the weakness of the costae, bu.t, where 

present, generally affects those that are not far from 

the edge of the sulcus. In one paratype (USNM 

167761) the fourth and fifth costae from the edge 

of the sulcus at either side are bifurcated anteriorly. 

This specimen (pl. 13, fig. 12) has a strong concentric growth constriction 4 mm from the anterior 

margin, along which line all the costae in the sukus 

bifurcate, so that between this constriction and the 

anterior margin, 10 costae are present in the sulcus. 

Assignment of this species to Brachythyrinn is 

based upon the shape of the costae and absence of 

capillate micro-ornament, which show that it is not 

an Anthracospirije1·, and the wide hinge line and 

pointed cardinal extremities, which are not in accord with an assignment to Brachythyris \)r one of 

its allied genera. The transverse shape and concentrically lirate to lamellose micro-ornament are typical of Brachythyrina. 

Types.-Holotype USNM 167760, paratypes 

USNM 167761-167763 (5 paratypes). 

Occurence and number of specimens.-Horseshoe 

Shale Member: collection 41 (6), Teton County. 

Genus NEOSPIRIFER Fredericks, 1924 

Neospirifer praenuntius Easton 

Plate 13, fi.gure 14 

Neospirifer p1·aermntius Easton, 1962, p. 71, 72, pl. 9, figs. 24, 

25. 

Spirijer shoshonensis Branson and Greger. Easton, 1962 

[part], p. 70 [not pl. 9, figs. 21, 22J. 

This species is represented in our Amsden collections by a single fragment. It consists of the posterior part of the ventral surface of a pedicle valve, 

showing the median sulcus occupied by five costellae, 

the middle one separated slightly by a narrow interspace from the two costellae at either side. Two 

fascicles of costellae are present on the lateral slopes 

at either side of the sulcus, separated from one 

another by rather deep rounded grooves. The fragment is 9 mm long and 10 mm wide. The identification of this specimen is based upon direct comparison with Easton's type material from the Heath 

Formation of Montana. 

Easton (1962, p. 70, 72) listed both Spirije1~ shoshoensis and N eospirifer p1·aenuntius from USGS 

locality 13370-PC in the Heath Formation. His 

specimens from that locality are labeled S. shoshonensis. In my opinion, further discussed elsewhere in this paper under Anthracospirifer cur·-

vilateralis Easton, true S. shoshonensi.c; does not occur in the Big Snowy and Amsden Groups in central Montana. Easton's specimens from locality 

13370-PC, so labeled, should be referred to N eospirifer praenuntius and in part to Anthracos~irifer 

cu1·vilateraUs, which also occurs at that locality. 

Figu1·ed specimen.--VSNM 167764. 

OccUITence.-Moffat Trail Limestone Member: 

collection 120, Teton County. 

Superfamily SPIRIFERINACEA 

Family SPIRIFERINIDAE Davidson 

Genus RETICULARIINA Fredericks, 1916 

Reticulariina browni (Branson and Greger) 

Plate 13, figures 23, 24, 30-46 

Spi1·ijerina browni Branson and Greger, 1918, p. 316, 317, pl. 

18, figs. 15, 17. 

Composita blackwelderi C. Branson, 1937, p. 657, pL 89, figs. 

18-20. 

Reticulwriina spinosa (Norwo·od and Pratten). Eas1ton, 1962 

[part], p. 83-85 [not pl. 10, fi.gs. 12-16]. 

Diagnosis.-Spiriferinid with six to seven rounded 

plications at either side of fold and sulcus in mature 

shell; surface covered by numerous tiny spines. 

Description.-Shell punctate, moderately small, 
D76 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

wider than long; cardinal extremities rounded, 

greatest width a little anterior to hinge. Lateral 

slopes on both valves ornamented by six to seven 

rounded to rarely subangular plications with narrower interspaces, crossed near anterior margin by 

a few chevronlike growth lamellae. 

Pedicle valve strongly convex, greatest curvature 

in umbonal region; interarea moderately high, concave, subtriangular, well delimited from umbonal 

slopes by angular margins which diverge from beak 

at an angle of 120°; sides of delthyrium diverging 

at angle of 45°. Median sulcus prominent, having 

steeply sloping sides and moderately broad shallowly 

concave bottom commonly occupied by low costa in 

adult shells. Surface spines small, closely spaced, 

Dimensions (in mm) .-

Length ------------------------------------

Maximum width ----------------------------

Width of hinge ----------------------------- Thickness ___________________ -- _ ------------

Depth of pedicle valve -----------------------

Depth of brachial valve --------------------- Height of interarea (pedicle valve) _________ _ 

1 Twice the half width. 

USNM 

168442 

15.5 

18.3 

15.2 

11.5 

9.0 

6.5 

3.0 

Discussion.-Three syntypes are in the University 

of Missouri collections of which one (UM 2656) 

figured by Branson and Greger (1918, pl. 19, fig. 

15) and in the present report on plate 13, figures 32-

36 and 43 is hereby designated the lectotype. The 

other two specimens are designated paralectotypes. 

These include one (UM 2650) figured by Branson 

and Greger (1918, pl. 18, fig. 17) and another unfigured specimen under the same U:M number, 

ground down on the pedicle-valve side to f;how the 

median septum and dental plates. 

The early neanic stage of this species was described and figured by C. C. Branson (1937) under 

the name "Composita blackwelderi n. sp." A reexamination of Branson's cotypes (syntypes) or 

C. blackwelderi has disclosed the presence of punctate shell structure and small spines scattered over 

the surface. The punctae and spine bases can be 

seen particularly well on a syntype (UM 6584) 

figured by Branson (1937, p. 98, fig. 18) and hereby 

designated as lectotype of C. blackwelderi. All of 

Branson's types of "Cmnposita blackwelder'i'' are 

juvenile specimens of Reticulariina browni. 

In this stage, at shell lengths of 1.3 to 1.6 mm, 

the fold and sulcus are well developed, along with 

the pair of plications that border the sulcus. The 

next plication on each lateral slope of the pedicle 

valve is just beginning and barely perceptible. On 

but two to three times further apart than punctae, 

most prominent in sulcus and in furrows between 

plications. Interior of pedicle valve with pair of 

dental plates that extend about one-quarter length 

of valve and strong median septum reaching to approximate middle of valve. 

Brachial valve less convex than pedicle valve and 

slightly shallower, greatest curvature in umbonal 

region, greatest depth at anterior end of fold. Fold 

well defined with steep sides and gently rounded to 

nearly fiat top delimited from sides by subparallel 

subangulations. Interarea very low, almost linear. 

Surface spines present but generally difficult to see 

on mature specimens. Interior of mature brachial 

valve not known. 

USNM 

168443 

12.5 

1 16.4 

9.0 

9.0 

7.0 

4.5 

2.7 

USNM 

168~44 

4.5 

4.7 

3.7 

2.2 

1.1 

USNM 

168~45 

3.5 

4.9 

4.0 

1.8 

UM 

658~ 

1.6 

1.9 

0.5 

1.0 

the brachial valve the plications at either side of 

tre fold begin before the fold, resulting in an ornamentation that consists of a small triangle (the 

fold) in front of a chevron (the diverging plications). The spines are very small and scattered over 

both valves. 

The late neanic state has been observed in silicified specimens (pl. 13, figs. 23, 24), from the bluffs 

of Bighorn Canyon opposite Devils Canyon, just 

across the State border in Montana. At shell lengths 

of 4.0 and 4.5 mm the pedicle valve is subcircular 

to suboval, ornamented by four or five low rounded 

plications on each lateral slope, some specimens 

with a faint costella occupying the middle of the 

sulcus. The interior of the pedicle valve bears a 

pair of short dental plates that reach nearly onequarter of the way forward from the beak, connecting the inside of the two plications that border 

the sulcus with the sides of the delthyri urn. Between 

these, a low narrow median ridge extends forward 

from the beak one-third to two-fifths of the distance 

from beak to anterior margin. 

The brachial valve is transversely oval in outline, 

not quite as deep as the pedicle valve but slightly 

more convex, broadly arched in anterior profile. The 

median fold is broad and rounded, slightly flattened 

on top anteriorly, some specimens having a faint 

median groove; three or four low rounded plications, 
BRACHIOPODA OF THE AMSDEN FORMATION D77 

separated by slightly narrower rounded grooves, occupying each lateral slope. 

Internally the brachial valve cardinalia consist of 

a diverging pair of inner and outer socket ridges at 

either side of a tiny triangular cardinal process, enclosing a socket at the distal end of each. Attached 

to the inner socket plates and slightly dorsad and 

anterior to each are a pair of triangular crural 

bases from which the crura extend almost parallel 

to the floor of the valve. Details of the spiralia are 

not preserved. 

Surfaces of both valves bear short tiny spines, 

directed anteriorly or radially, scattered randomly 

over the posterior part of the valves but tending to 

form fringelike rows along or between thin irregular concentric lamellae along and near the anterior 

margin. 

Comparisons and affinities.-The classification of 

this species as a Reticulariina has been given careful consideration because the surface spines are so 

tiny that Branson and Greger (1918, p. 317) believed that none were present. Examination under 

the binocular microscope has shown that these little 

spines are hollow and are not like the granules that 

cover the surface of the shell in the allied genus 

Spiriferellina. 

Among the American Mississippian species formerly classified loosely as "Spi1·ijerina" and including those shells with smooth to spinose surfaces are 

the following: 

1. Surface smooth, partly to entirely covered by fine 

granules: Spiriferina spinosa var. campestris 

White, S. salwmensis Weller, S. subspinosa Weller, and Spiriferellina lata Lane. 

2. Surface covered with pustules: Spiriferina spinosa var. cochisensis Hernon. 

3. Surface covered with small spines: Spiri.fer spinosus Norwood and Pratten, S. norwoodanus 

Hall, Spiriferina gonionota Meek, and S. 

browni Branson and Greger. 

Reticulariina spino.~a (Norwood and Pratten) differs from R. browni in having fewer plications 

(four or five on each lateral slope), a narrower and 

more rounded fold and sulcus, and coarse surface 

spines that are much more widely spaced than the 

tiny spines of R. browni. 

R. gonionota (Meek) also has fewer plications 

(three to five on each lateral slope in Great Basin 

specimens), the fold is more prominent than in 

either R. spinosa or R. brown1:, and the spines are 

somewhat smaller than in R. spinosa but considerably larger than those of R. browni and sparser than 

in the other two species. 

Reticulariina norwoodana (Hall) is the smallest 

of the North American reticulariinas, having three 

to five low rounded plications, a narrow shallow sulcus in the pedicle valve, and low fold in the brachial 

valve. Tiny spines, but fairly large in proportion to 

the shell, are scattered over the surface. Although 

Weller (1914, p. 296) referred to these as papillae, 

specimens from the Salem Limestone at Stinesville, 

Ind., in the U.S. Geological Survey collections show 

that these are actually anteriorly directed short hollow spines. Its small size, fewer spines, narrower 

and less prominent fold and sulcus, and fewer and 

less elevated plications distinguish this species without difficulty from R. browni. 

Reticulariina browni is restricted to the Carlinia 

a1nsdeniana Subzone in Fremont County, Wyo. At a 

locality just across the State border, in Carbon 

County, Mont., this species was found with fossils 

typical of the Compos1:ta poposiensis Subzone, but 

lacking C. poposiensis. 

Types.-Lectotype, UM 2656; paralectotypes, UM 

2650 (two specimens) ; hypotypes, USNM 168442-

168445 (four specimens) ; of Composita blackwelde'ri C. Branson: lectotype, UM 6584 (part) ; paralectotypes, UM 5683, 6584 (three specimens) . 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 26b (23), 27 (21), 36a 

(21 +fragments), 36b (lectotype), 36c (2 paralectotypes), 36d (5), A (1), B (3), E (3), Fremont 

County, Wyo., collection 69 (11), Carbon County, 

Mont. 

Suborder RETZIIDINA 

Superfamily RETZIACEA Waagen 

Family RETZIIDAE Waagen 

Genus EUMETRIA Hall, 1864 

Eumetria sulcata Burk 

Plate 13, figures 19, 20, 25-29 

Eumetria 'Verneuiliana (Hall). Branson and Greger, 1918, p. 

320, pl. 18, figs. 20, 21. 

Eumetria sulcata Burk, 1954, p. 14, pl. 1, figs. 31-34. 

Diagnos·is.-EumetTia having 35 to 43 costae in 

pedicle valve and 36 to 42 in brachial valve; costae 

low, rounded, and separated by very narrow intercostal grooves. Shallow broad median sulcus present 

in pedicle valve in some specimens. 

Dimensions (in mn~) .-

USNM 

168446 

Length __________ 22.7 

Width ___________ 21.8 

Width of hinge ___ ? 

Thickness ________ 11.7 

uw 

JT-:!.11 

17.3 

14.5 

4.0 

9.2 

UM 

:!653 

1 13.5 

13.5 

4.8 

8.3 

USNM 

168447 

12.8 

12.3 

3.2 

6.9 

1 Small fragment broken off at anterior margin, necessitating estimate. 

Discussion.-In this species, each valve has approximately 38 costae. The shape of the shell and 
D78 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

prominence of the sulcus have a considerable range 

of variation. More elongate specimens with deeper 

valves are more likely to develop a sulcus. Broader 

shells of subequal length and width are commonly 

shallower and without a wel:l-defined sulcus. 

Included in the table above is a specimen (UM 

2653) figured by Branson and Greger (1918, pl. 18, 

fig. 21) as E. verneuiliana (Hall). Branson and Greger's figured specimens are from Cherry Creek; they 

are silicified and presumably are from the Composita poposiensis Subzone. They are regarded as topotypes of Eumetria sulcata Burk. 

Also belonging in this species are specimens identified by Shaw and Bell (1955, p. 335, fig. 1) as E. 

verneuiliana, preserved in calcareous sandstone and 

coming from the Carlinia amsdeniana Subzone at 

Cherry Creek. The broad low costae on these specimens, of which less than 45 are normally present on 

each shell, show that they cannot be assigned to E. 

verneuiliana, which has narrow raised subrounded 

to subacute costae and mode·rately broad intercostal 

sulci, generally more than 50 on each valve. 

Eumetria sulcaia, as pointed out by Burk (1954, 

p. 14), is close to E. costata (Hall). One might even 

consider it a subspecies of E. costata because the 

number of its costae falls within the range of Hall's 

species-30 to 42. However, typical E. costata, although similar in shape to some specimens of E. 

sulcata, normally has a slightly narrower, larger, 

and more tumid shell in which the pedicle valve is 

invariably convex near the anterior margin, showing 

no sign of a sulcus. Typical E. costata, moreover, 

has fewer than 35 costae on each valve. It seems 

reasonable, therefore, to consider E. sulcata a valid 

species. 

Types.-Holotype, UW IT-231; hypotypes UM 

2653, USNM 168457, 168458; additional measured 

specimens, USNM 168446, 16844 7. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 26b (3), 27 (3), 28 (6), 

29 (6), 30 (6), 31 (6), 32 (5), 35 (7), 36a (9), 36e 

(1), 38 (9), 39 (1), B (3), D (1), Fremont County, 

Wyo.; 69 (2), Carbon County, Mont. Ranchester 

Limestone Member : collection 146 ( 8) , Teton County, Wyo. 

Order TEREBRATULIDA 

Suborder TEREBRA TULIDINA 

Superfa'mily DIELASMA T ACEA 

Family CRANAENIDAE Cloud 

Genus GIRTYELLA Weller, 1911 

Girtyella cf. G. indianensis (Girty) 

Plate 13, figuves 15-18, 21, 22 

?Girtyella indianensis (Girty). C. Branson, 1937, p. 657. 

A fairly complete specimen (UM 10890) collected 

by C. C. Branson from the Little Popo Agie River 

area is apparently the one upon which the record 

cited above was based. The calcareous preservation 

and limonite adhering to this shell indicates that it 

comes from the Carlinia amsdeniana Subzone. Figured here on plate 13, figures 15-18, it measures (in 

mm) : length 13.5, width (twice the half width) 

11.2, and thickness 6.5. The greatest thickness occurs about one-third of the way forward in the 

brachial valve and near the middle of the pedicle 

valve; greatest width is at the middle of the shell. 

Part of one side is missing, and some distortion in 

the anterior part of the shell has obscured the details 

of the sulcus and fold. The sulcus begins near the 

middle of the pedicle valve and is moderately prominent. The curved beak is well defined and nearly 

erect at the tip. A short median septum is visible in 

the apical part of the brachial valve. Shell structure 

is punctate. 

A brachial valve preserved in calcareous sandstone also belongs in this genus. It was collected in 

place by W. G. Bell from the Carlinia amsdeniana 

Subzone at Cherry Creek. The valve is broadly oval, 

its length 10.5, width 9.2, and depth 2.0 mm, with a 

very narrow strip of the anterior edge missing. At 

the anterior end, an incipient median sulcus and a 

pair of faint lateral sulci delimiting between them a 

pair of small folds are very weakly developed. A 

median septum 4 mm long extends from the umbo. 

The shell is minutely punctate. 

Also included here tentatively is one of the paratypes (UM 6585) of Rhipidomella gregeri C. Branson. This tiny shell has the shape of a young Girtyella or Cranaena and has a finely punctate shell 

structure. It measures 1.5 mm long and 1.3 mm wide. 

A narrow shallow sulcus is present in the pedicle 

valve. The internal characters, however, could not 

be ascertained. 

The characters of the two larger shells are close 

to those of G. indianensis (Girty), and all three 

could belong to this or a closely allied form. 

Figu'red specimens.-UM 10890, UW A11118. 

Mentioned specimen.-UM 6585. 

Occurrence and number of specimens.-Horseshoe 

Shale Member: collections 28 (1), 36d (2), Fremont County. 

Incertae sedis 

Genus SELENELLA Hall and Clarke, 1894 

Selenella 1 walteri (C. Branson) 

Selenella? walteri C. Branson, 1937 [part], p. 657, pl. 89, fig. 

21 [not fig. 22.]. 

Among the tiny juvenile shells illustrated by C. 

C. Branson (1937) were three specimens assigned 

with question to Selenella. Two of these, the para-
BRACHIOPODA OF THE AMSDEN FORMATION D79 

types, are subtriangular in shape and interpreted 

here as probably juvenile examples of Pugnoides 

quinqueplecis Easton. The holotype, however, is 

elongate-oval and is not recognized as a rhynchonellid. Until fairly complete growth suites become 

available, it does not seem posible to connect S.? 

walteri with any adult form. The name, now re .. 

stricted to the holotype, is regarded as belonging to 

a species inquirenda. 

Type.-Holotype, UM 6581. 

Occurrence.-Horseshoe Shale Member: collection 

36b, Fremont County. 

REFERENCES CITED 

Allen, A. T., Jr., and Lester, J. G., 1954, Contributions to the 

paleontology of northwest Georgia: Georgia Geol. Survey 

Bull. 62, 166 p., 42 pls., 7 maps. 

Bassler, R. S., 1909, The cement resources of Virginia west 

of the Blue Ridge: Virginia Geol. Survey Bull. 2A, 309 

p., 30 pls., 30 figs. 

Beede, J. W., 1900, Carboniferous invertebrates: Kansas 

Univ. Geol. Survey Rep.t. 6, p. 1-187. 

--- 1906, Fauna of the Salem Limestone; Brachiopoda: 

Indiana Dept. Geology Ann. Rept. 30, p. 1297-1334, pls. 

17A-22. 

Blackwelder, Eliot, 1918, New geological formations in western Wyoming: Washington Acad. Sci. Jour., v. 8, p. 

417-426. 

Boutwell, J. M., 1912, Geology and ore deposits of the Park 

City district, Utah: U.S. Geol. Survey Prof. Paper 77, 

231 p., 44 pls. 18 figs. 

Branson, C. C., 1930, Paleontology and stratigraphy of the 

Phosphoria Formation: Missouri Univ. Studies, v. 5, no. 

2, 99 p., 16 pls., 1 fig. · 

--- 1936, Carboniferous sh·atigraphy of Wyoming [abs.]: 

Geol. Soc. America Proc. 1935, p. 391-392. 

--- 1937, Stratigraphy and fauna of the Sacajawea Forformation, Mississippian, of Wyoming: Jour. Paleontology, v. 11, no. 8, p. 650-660, pl. 89. 

--- 1939, Pennsylvanian formations of central Wyoming: 

Geol. Soc. America Bull., v. 50, no. 8, 1199-1226, 3 pls., 

2 figs. 

--- 1948, Bibliographic index of Permian invertebrates: 

Geol. Soc. America Mem. 26, 1049 p. 

Branson, E. B., 1918, Geology of Missouri: Missouri Univ. 

Bull., Sci. Ser., v. 19, no. 15 (Eng. Expt. Sta. Ser. 19), 

172 p., 5 pls., 59 figs. 

Branson, E. B., and Greger, D. K., 1918, Amsden Formation 

of the east slope of the Wind River Mountains of Wyoming and its fauna: Geol. Soc. America Bull. v. 29, p. 

309-326, pls. 18, 19, 1 fig. 

Brown, Thomas, [1838-] 1849, Illustrations of the fossil 

conchology of Great Britain and Ireland * * * : London, 

273 p., 116 pls. 

Bruguiere, J. G., 1797, Tableau encyclop€dique et methodique 

des trois regnes de la nature, v. 2, Vers. Coquilles, Mollusques et Polypiers: Paris, pls. 190-286. 

Buckman, S. S., 1906, Brachiopod nomenclature: Annals and 

Mag. Nat. History, ser. 7, v. 18, no. 107, p. 321-327. 

Burk, C. A., 1954, Faunas and age of the Amsden Formation 

in Wyoming: Jour. Paleontology, v. 28, no. 1, p. 1-16, 1 

pl., 6 figs. 

Butts, Charles, 1917, Descriptions and correlation of the 

Missis1sippian formations of western Eentucky: Frankfort, Ky., Kentucky Geol. Survey, 119 p., 28 pls. 

--- 1926, Geology of Alabama-The Paleozoic rocks: Alabama GeoL Survey Spec. Rept. 14, p. 41-23,0, 74 pls., 4 

figs. 

--- 1941,Geology of the Appalachian Valley in VirginiaPt. 2, Fossil plates and explanations: Virginia Geol. 

Survey Bull. 52·, pt. 2, 271 p., pls. 64-135. 

Chao, Y. T., 1927, Productidae of China. Pt. 1: Producti: 

Palaeontologia Sinica, ser. B, v. 5, no. 2, p. 1-243, 16 pls. 

Cloud, P. E., Jr., and Barne·s, V. E., 1948, The Ellenburger 

Group of central Texas: Texas Univ., Bur. Econ. Geology Pub. 4621 (1946), 473 p., 45 pls., 8 figs. 

Cooper, G. A., and Muir-Wood, H. M., 1951, Brachiopod 

homonyms: Washington Acad. Sci., Jour., v. 41, no. 6, 

p. 195-19·6. 

Croneis, Carey, 1930, Geology of the Arkans·as Paleozoic 

area: Arkansas Geol. Survey Bull. 3, 457 p., 45 pls., 30 

figs. 

Darton, N. H., 1906, Geology of the Bighorn Mountains: U.S. 

Geol. Survey Prof. Paper 51, 129 p., 47 pls., 14 figs. 

Davidson, Thomas, 1866, Notes on the Carboniferous Brachiopoda collected by Captain Godwin-Austen in the Valley 

of Kashmere: Geol. Soc. London Quart. Jour., v. 22, p. 

39-45, pl. 2. 

Dunbar, C. 0., and Condra, G. E., 1932, Brachiopoda of the 

Pennsylvanian System in Nebraska: Nebraska Geol. Survey Bull., 2d ser., no. 5, 377 p., 44 pis.~ 25 figs. 

Dutro, J. T., Jr., and Sando, W. J., 1963 New Mis,sissippian 

formations and faunal zones in Chesterfield Range, Portneuf quadrangle, southeast Idaho: Am. Assoc. Petroleum 

Geologists Bull., v. 42, no. 11, p. 1963-1986, 6 figs. 

Easton, W. H., 1942, Pitkin Limestone of northern Arkansas: 

Arkansas Geol. Survey Bull. 8, 115 p., 12 pis., 10 figs. 

--- 1962, Carboniferous formations and faunas of central 

Montana: U.S. Geol. Survey Prof. Paper 348, 126 p., 14 

pls., 1 fig. 

Elias, M. K., 1957, Late Mississippian fauna from the Redoak Hollow Formation of southern Oklahoma. Pt. 2, 

Brachiopoda: Jour. Paleontology, v. 31, no. 3, p. 487-527, 

pls. 51-58, 26 figs. 

Fischer de Waldheim, Gotthelf, 1829, Surquelques fossiles du 

gouvernement de Moscou: Soc. Imper. Naturalistes 

Moscou Bull., v. 1, no. 12, p. 375-376. 

Foster, G. L., 1942, Spirifer occidentalis Girty: Jour. Paleontology, v. 16, no. 2, p. 249-250, 1 fig. 

Fredericks, George, 1916, [The palaeontological notes. 2. On 

some upper Palaeozoic Brachiopoda of Eurasia]: Comite 

Geol. Petrograd Mem., new ser., v. 156, p. 1-87, 5 pls., 

24 figs. [In Russian]. 

--- 1924, 0 Verkhne-Kammenougol'nykh spiriferidakh 

Urala [On upper Carboniferous spirifirids from the 

Urals]: Geol. Komitet, Leningrad, Izv., v. 38 (1919), no. 

2, p. 295-324, 7 figs. 

--- 1925, Fauna Kynovskogo izvestnyaka na Urala 

[Fauna of the Kyn limestone in the Urals]: Geol. 

Komitet, Leningrad, Izv., v. 48, no. 3, p. 369-413, pls. 20, 

21, 6 figs. 

French, E. M., Jr., 1940, Characteristic fossils of Maryland: 

Compass, v. 20, no. 4, p. 323-339, pls. 1-8. 

Gehrig, J. L., 1958, Middle Pennsylvanian brachiopods from 

the Mud Springs Mountains and Derry Hills, New 
D80 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Mexico: New Mexico Bur. Mine's and Mineral Resources 

Mem. 3, 24 p., 6 pls., 1 fig. 

Girty, G. H., 1903, 'The Carboniferous formations and faunas 

of Colorado: U.S. Geol. Survey Prof. Paper 16, 546 p., 

10 pis. 

--- 1904, Note on the Carbonife.rous fos,sils, in Ransome, 

F. L., The geology and ore deposits of the Bisbee quad,. 

rangle, Arizona: U.S. Geol. Survey Prof. Paper 21, p. 

46-54, pls. 10-11. 

--- 1909, The fauna of the Ganey Shale of Oklahoma: 

U.S. Geol. Survey Bull. 377, 106 p., 13 pis. 

--- 1910, New genera and spedes of Carboniferous fossils from the Fayetteville Shale of Arkansas: New York 

Acad. Sci. Annals, v. 20, no. 3, pt. 2, p. 189-238. 

--- 1911, The fauna of the Moorefield Shale of Arkansas: 

U.S. Geol. Survey Bull. 439, 148 p., 15 pls. 

--- 1915a, Fauna of the Wewoka Formation of Oklahoma: U.S. Geol. Survey Bull. 544, 353, p. 35 pls. 

--- 1915b, The fauna of the Batesville Sandstone of 

northern Arkansas: U.S. Geol. Survey Bull. 593, 170 p., 

11 pls. 

--- 1920, Carboniferous and Triassic faunas [of Utah]: 

U.S. Geol. Survey Prof. Paper 111, p. 641-648, 6 pls. 

--- 1927, Descriptions of new s,pecies of Carboniferous 

and Triassic fossils [of southeastern Idaho]: U.S. Geol. 

Survey Prof. Paper 152, p. 411-446, pis. 22-25, 27, 28, 

30 (p. 62 ff). 

--- 1935, An unrecorded structure in certain semireticulate Producti: J oor. Paleontology, v. 9, no. 1, p. 7-9, 

pl. 2. 

Gordon, Mackenzie, Jr., 1966, New spinose early Meramec 

(Upp,er Mis·sissippian) productoid brachiopods: Jour. 

Paleontology, v. 40, no. 3, p. 573-584, pis. 69-70. 

--- 1971, Carlinia, a Late Mississippian genus of Productidae from the western United States: Smithsonian 

Contr. Paleobiology, no. 3, p. 257-265, 1 pl. 

Gordon, Mackenzie, Jr., and Duncan, H. M., 19,70, Bios.tratigraphy and correlation, in Tooker, E. W., and Roberts, 

R. J., Upper Paleozoic rocks in the Oquirrh Mountains 

and Bingham mining district, Utah: U.S. Geol. Survey 

Prof. Paper 629-A, p. A38-A57, fig. 13. 

Grabau, A. W., and Shimer, H. W., 19·09, North American 

index fossils; Invertebrates, v. I: New York, 853 p., 

1,210 figs. 

Grant, R. E., 1965, The brachiopod superfamily Stenos,cismatacea: Smithsonian Misc. Colin., v. 148, no. 2 (Smithsonian Inst. Pub. 4569·), 192 p., 24 pis., 34 figs. 

Grinnell, R. S., Jr., and Andrews, G. W., 1964, Morphologic 

studies by the brachiopod genus Composita: Jour. Paleontology, v. 38, no. 2, p. 227-248, pls. 37-39, 9 figs. 

Gunnel, F. H., 1932, The Brazer Formation of northern Utah 

and its telotremate brachio.pods: Am. Midland Naturali·st, v. 13, no. 5, p. 282-301, 1 pl. 

Haas, Otto, 1946, Annotated faunal list of the Glen Dean 

Formation of Crane, Indiana: Am. Mus. Novitate,s 1307, 

9 p. 

Hall, James, 1852, Geology and paleontology, in Stansbury, 

Howard, Exploration and survey of the valley of the 

Great Salt Lake of Utah, including a reconnaissance of 

of a ne'w route through the Ro·cky Mountains: U.S. 32d 

Gong., Spec. S.ess., Senate Exec. Doc. 3, p. 399-414, 4 pls. 

--- 1858, Report on the geologic,al survey of the State of 

Iowa * * * v. 1, pt. 2, Paleontology: Albany, N.Y., p .. 

473-724, 29 pls., figs. 52-118. 

--- 1860, Descriptions of new species of fossils, from thE 

Hamilton Group of western New York, with notice's of 

others from the same horizon in Iowa and Indiana : New 

York State Cabinet Nat. History, Ann. Rept. 13, p. 76-94. 

--- 1863, Obs·ervations upon some of the Brachiopoda, 

with reference to the characters of the genera Cryptonella, Centronella, Meristella, Trematospira, Rhynchospira, Retzia, Leptocoelia, and allied forms: New York 

State Cabinet Nat. History, Ann. Rept. 16, p. 38-61, 54 

figs. 

--- 1883, Brachiopoda, plates and explanations, in New 

York State Geologist, Report * * * for the year 1882 

[s·econd annual]: Albany, N.Y., Weld, Parsons and Co., 

[2] p., pls. 34-61. 

Hall, Jame•s, and Clarke, J. M., 1893-1894, An introduction 

to the study of the genera of Palaeozoic Brachiopoda: 

New York Geol. Survey, Palaeontology, v. 8, pt. 1, 367 

p., 20 pls., 39 figs. (1893); pt. 2, 394 p., pls. 2:1-84, figs .. 

40-271 (1894). [Some fascicles of pt. 2 issued in 1893; 

first issue in entirety 1895]. 

Hall, James, and Whitfield, R. P., 1877, Palaeontology. Part 

II: U.S. Geol. Explor. 40th Parallel (King), v. 4, p. 

199-302, 7 pls. 

Hernon, R. M., 1935, The Paradise Formation and its fauna: 

Jour. Paleontology, v. 9, no. 8, p. 653-69·6, pls. 80-82, 1 

fig. 

Hoare, R. D., 1960, New Pennsylvanian Brachiopoda from 

southwest Missouri: Jour. Paleontology, v. 34, no. 2, p. 

217-232, pls. 1-2. 

--- 1961, Desmoinesian Brachiopoda and Mollusca from 

southwest Missouri: Missouri Univ. Studies, v. 36, 263 

p., 23 pls., 1 fig., 1 chart. 

International Commission on Zoological Nomenclature, 1961, 

International code of zoological nomenclature, adopted by 

the XV International Congress of Zoology: London, 

Internat. Trust Zool. Nomenclature, 176 p. 

Ivanov, A. P., 19,25, [Sur la systematique et la biologie du 

genre Spirifer et de quelques brachiopodes de Cu et 

Cm du Gouvernment de Moscou]: Soc. Nat. Moseou, 

Sec. Geol., Bull., v. 3, p. 105-123 [in Russian with 

French summary]. 

Kelly, W. A., 1930, Lower Pennsylvanian faunas from 

Michigan: Jour. Paleontology, v. 4, no. 2, p. 129-15.1, 

pl. 11. 

Keyes, C. R., 1888, On the fauna of the Lower Coal M;easures 

of central Iowa: Acad. Nat. Sci. Philadelphia Proc. 1888, 

v. 2, p. 222-246, pl. 12. 

Keyes, C. R., 1894, Paleontology of Missouri, pit. 2: Missouri 

Geol. Survey, v. 5, 266 p., pl.s. 33-5·6. 

Kindle, E. M., 1908, The fauna and stratigraphy of the 

Jefferson Limestone in the northern Rocky Mountain 

region: Bull. Am. Paleontology, v. 4, no. 20, 39 p., 4 pls. 

King, R. E., 1930, Geology of the Glass Mountains, Texas. 

Part II. Faunal summary and correlation of the Permian 

formations with description of Brachiopoda: Texas Univ., 

Bur. Econ. Geology Bull. 3042, 245 p., 44 pls., 5 figs. 

King, William, 1850, A monograph of the Permian fossils 

of England: Palaeontograph. Soc., Mon. 3, 258 p., 29 pls. 

Lan-e, N. G., 1963, A silicified Morrowan brachiopod faunule 

from the Bird Spring Formation, southern Nevada: 

Jour. Paleontology, v. 37, no. 2, p. 379-392, pls. 43-45, 

6 figs. 
BRACHIOPODA OF THE AMSDEN FORMATION D81 

--- 1964, Gostation patterns in Early Pennsylvanian 

spiriferids: Jour. Paleontology, v. 38, no. 4, p. 781-785, 

1 fig. 

Love, J. D., 1939, Geology along the southern margin of the 

Absaroka Range, Wyoming: Geol. S.oc. America, Spec. 

Paper 20, 134 p., 17 pls., 3 figs. 

McC:oy, Fred~rick, 1844, A synopsis of the characters of 

the Carboniferous limestone fossils nf Ireland: Dublin, 

Univ. Press, 207 p., 29 pls. 

McKee, E. D., 1938, The environment and history of the 

Toroweap and Kaibab Formations of northern Arizona 

and southern Utah: Carnegie Inst. Washington Pub. 

492, 268 p., 51 pls., 37 figs. 

Mamet, B. L., 1970, Carbonate microfacies of the Windsor 

Group (Carboniferous), Nova Scotia and New Brunswick: Canada Geol. Survey Paper 70-21, 120 p., 19 pls., 

16 figs. 

--- 1975, Carboniferous Foraminifera and alg.ae of the 

Amsden Formation (Mississippian and Pennsylvanian) 

of Wyoming: U.S. Geol. Survey Prof. Paper 848-B. [In 

press.] 

Mark, C. G., 1912, The fossils of the Conemaugh Formation 

in Ohio: Ohio Geol. Survey, ser. 4, Bull. 17, p. 261-318, 

pis. 14-16. 

Mather, K. F., 1915, The fauna of the Morrow Group of 

Arkans,as and Oklahoma: Denison Univ. Sci. Lab. Bull. 

18, p. 59-284, 16 pls. 

Maughan, E. K., and Roberts, A. E., 1967, Big Snowy and 

Amsden Groups and the Mississippian-Pennsylvanian 

boundary in Montana: U.S. Geol. Survey Prof. Paper 

554-B, 27 p., 4 pis., 7 figs. 

Meek, F. B., 1872, Report on the paleontolo,gy of eastern 

Nebraska, with some remarks on the Carboniferous 

rocks of that district, in Hayden, F. V., Final report of 

the United States Geological Survey of Nebraska and 

portions of adjacent territories: U.S. 42d Gong., 1st sess., 

House Exec. Doc. 19, p. 83-239, 11 pis., 8 figs. 

--- 1877, Palaeontology. Part I: U.S. Geol. Explor. 40,th 

Parallel (King), v. 4, p. 3-197, 17 pls. 

Meek, F. B., and Worthen, A. H., 1873, Descriptions of in!Vertebrates frpm Carboniferous system. Illinois Geol. Survey, 

v. 5, p. 321-619, 32 pls. 

Miloradovich, B. V., 1945, Some data on the morphology of 

productid shells: Akad. N auk SSSR, Izv., Ser. Bioi. 

(1945), no. 4, p. 485-500. 

Minato, Masao, 1953, On some reticulate Spiriferidae: 

Paleont. Soc. Japan, T1·ans. and Proc., new ser., no. 11, 

p. 65-73, 3 figs. [summary in Japanese]. 

Moore, R. G., ed., 1965, T'reatis·e on invertebrate paleontology. 

Part H, Brachiopoda, by Alwyn Williams and others: 

New York and Lawrence, Kans., Geol. Soc. America and 

Univ. Kansas Press, 2 v., 947 p., 746 figs. 

Mol'ey, P. S., 1935, Ostracoda from the Amsden Formation 

of Wyoming: Jour. Paleontology, v. 9, no. 6, p. 474-482, 

pl. 54. 

Morgan, G. D., 1924, Geology of the Stonewall quadrangle, 

Oklahoma: Oklahoma Bur. Geology Bull. 2, 248 p., 53 

pls., 1 fig. 

Morningstar, Helen, 1922, Pottsville fauna of Ohio: Ohio 

Geol. Survey, 4th ser., Bull. 25, 312 p., 16 pls., 1 geol. 

sketch map. 

Morse, W. C., 1911, The fauna of the Maxville Limestone: 

Ohio State Acad. Sci. Proc., v. 5 ( S.pec. Paper 17), p. 

355-420, 36 figs. 

--- 1930, Paleozoic rocks [of Missis1sippi]: Mississippi 

Geol. Survey Bull. 23, 212 p., 23 pls. 15 figs., seetions. 

--- 1931, Pennsylvanian invertebrate fauna: Kentucky 

Geol. Survey, ser. 6, Rept., v. 36, Paleontology of Kentucky, p. 295-348, pis. 45-53, fig. 29. 

--- 1936, Tishomingo State Park, geologic history: Mississippi Geol. Survey Bull. 32, p. 7-36, 1 pl., topog. and 

index maps, 18 figs. 

Muir-Wood, H. M., 1928, The British Carboniferous Producti. II. Productus (sensu stricto) semireticulatus and 

longispinus groups: Great Britain, Geol. Survey ( Palaeontology), Mem. 3, pt. 1, 217 p., 12 pls. 

--- 1962, On the morphology and classification of the 

brachiopod suborder Chonetoidea: London, British Mus. 

(Nat. History), 132 p., 16 pls., 24 figs. 

Muir-Wood, H. M., and Cooper, G. A., 1960, Morphology, 

classification and life habits of the Productoidea 

(Brachiopoda) : Geol. Soc. America Mem. 81, 447 p., 135 

pis., 9 figs. 

Norwood, J. G., and Pratten, Henry, 1855, Notice of Producti found in the Western States and Territories, with 

descriptions of twelve new species: A cad. Nat. Sci. 

Philadelphia Jour., ser. 2, v. 3, pt. 1, p. 5-22, 1 pl. [preprint dated 1854.] 

Oehlert, D. P., 1890, Note sur differents groupes. etablis dans 

le genre Orthis et en particulier sur Rhipidornella Oehlert 

( =Rhipidmnys Oehlert, olim) : Jour. Conchyliologie, ser. 

3, v. 38, p. 367-374. 

Orbigny, Alcide d', 1847, Considerations zoologiques et 

geologiques sur les brachiopodes ou palliobranches: 

Acad. Sci., Paris, Gomptes Rendus, v. 25, p. 193-195, 

266-269. 

Peale, A. C., 187 4, Report [on the South Park region, Colorado]: U.S. Geol. and Geog. Survey Territories (Hayden), Ann. Rept. [7], 1873, p. 193-273. 

Plummer, F. B., 19510, The Carboniferous rocks of the Llano 

region of central Texas: Texas Univ. Pub. 4329, 170 p., 

22 pls., 14 figs., 4 charts. 

Plummer, F. B., and Moore, R. C., 1921, Stratigraphy of 

the Pennsylvanian formations of north central Texas: 

Texas Univ. Bull. no. 2132, 237 p., 27 pls., 19 figs. [1922]. 

Price, W. A., 1916, Notes on the paleontology of Raleigh, 

Wyoming, McDowell, and adjacent counties: West Virginia Geol. Survey, Raleigh, Wyoming, McDowell and 

adjacent Counties [Rept.], p. 663-734, pls. 30, 31. 

--- 1921, Notes on the paleontology of Nicholas County; 

Invertebrate fossils from the Pottsville Series: West 

Virginia Geol. Survey, Nicholas County [Rept.], p. 

751-788, 2 pls., 1 fig. 

Sadlick, Walter, 1955, Carboniferous formations of northeastern Uinta Mountains: Wyoming Geol. Assoc., Guidebook, lOth Ann. Field Conf., Green River Basin, 1955, 

p. 49-59, 4 figs. 

--- 1960, New name for Spirifer occidentalis (Girty) and 

and its geologic history: Jour. Paleontology, v. 34, no. 6, 

p. 1210-1214. 

Sando, W. J., 1968, A new member of the Madison Limestone 

(Miss,issippian) in Wyoming: GeoL Soc. America Bull., 

v. 79, no. 12, p. 1855-1858, 2 figs. 

--- 1975, Coelenterata of the Amsden Formation (Mississippian and Pennsylvanian) of Wyoming: U.S. GeoL 

Survey Prof. Paper 848-C [in press]. 

Sando, W. J., Gordon, Mackenzie, Jr., and Dutro, J. R., Jr., 

1975, Stratigraphy and geologic history of the Amsden 
D82 THE AMSDEN FORMATION (MISSISSIPPIAN AND PENNSYLVANIAN) OF WYOMING 

Formation (Mississippian and Pennsylvanian) of 

Wyoming: U.S. Geol. Survey Prof. Paper 848-A [in 

press]. 

Sayre, A. N., 1931, The fauna of the Drum Limestone of 

Kansas and wes:tern Missouri: Kansas Univ. Sci. Bull., 

v. 19, pt. 2, p. 75-202, 21 pls.; reprinted as Kansas Geol. 

Survey Bull. 17. 

Schellwien, E. T. T., 1900, Beitrage zur Sys,tematik der 

S.trophomeniden des oberen Palaozoicum: Neues J ahrb. 

Mineralogie, Geologie, Palaontologie, J ahrg. 1900, v. 1, 

p. 1-15, pl. 1, 9 figs. 

Shaw, A. B., 1955, The: Amsd:en Formation in southwestern 

and south-central Wyoming: Wyoming Geol. Assoc., 

Guidebook, lOth Ann. Fie:ld Con£., Green River Basin, 

1955, p. 60-63, 1 fig. 

Shaw, A. B., and Bell, W. G., 1955, Age of Amsden Formation, Cherry Creek, Wind R,iver Mountains, Wyoming: 

Am. Assoc. Petroleum Geologists Bull., v. 39, no. 3, p. 

333-337, 2 figs. 

Shimer, H. W., 1926, Upper Paleozoic faunas of the Lake 

Minnewanka S'ection, near Banff, Alberta: Canada, GeoL 

Survey, Bull. 42, 84 p. 

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

North America: New York, John Wiley and Sons, 837 

p., 303 pls. 

Shumard, B. F., amd Swallow, G. C., 1858, Descriptions of 

new fossils from the Coal Measures of Mis·souri and 

Kansas: Acad. Sci. St. Louis Trans., v. 1, p. 198-227. 

Smith, J. P., 1896, Marine fossils from the Coal Measures 

of Arkansas: Am. Philos. Soc. Proc., v. 35, no. 152, p. 

213-285, pls. 16-24. Reprinted as Stanford Univ., Hopkins Seaside Lab. Contr. Biology 9, p. 1-72, 1897. 

Snider, L. C., 1915, The paleontology of the Chester Group in 

Oklahoma: Oklahoma Geol. Survey Bull. 24, pt. 2, p. 67-

122, 7 pls., 1 chart. 

Spencer, R. S., 1967, Pennsylvanian Spiriferacea and Spiriferiancea of Kansas: Kansas Univ. Paleont. Contr., 

Paper 14, 35 p., 22 figs. 

StehH, F. G., 1954, Lower Leonardian Brachiopoda of the 

Sierra Diablo: Am. Mus. Na:t. History BulL, v. 105, art. 

3, 358 p., pls. 17-27, 55 figs. 

Stevens, G. H., 1962, Stratigraphic significance of Pennsylvanian brachiopods in the McCoy area, Colorado: Jour. 

Paleontology, v. 36, no. 4, p. 617-629, pls. 91-96, 2 figs. 

Sturgeon, M. T., and Hoare, R. D., 1968, Pennsylvanian 

brachiopods of Ohio: Ohio, Div. Geol. Survey Bull. 63, 

95 p., 22 pls., 14 figs. 

Sutton, A. H., 1938, Taxornomy of Mississippian Productidae: 

Jour. Paleontology, v. 12, no. 6, p. 537-569, pls. 62-66, 2 

figs. 

Swallow, G. C., 1860, Descriptions of new fossils from the 

Carboniferous and Devonian rocks of Missouri: Acad. 

Sci. St. L·ouis Trans., v. 1, p. 635-660. 

Thomas, A. 0., 1924, Some fossils from an outcrop in Des 

Moines: Iowa Acad. Sci. Proc., v. 30, p. 471-479, 2 pls. 

Ulrich, E. 0., 1917, The formations of the Chester Series in 

western Kentucky and their correlates elsewhere: Kerntucky Geol. Survey, 272 p., 1 fig., pls. A-H, 11 fossil pls. 

Waagen, W. H., 1882-1885, Salt Range fossils. v. 1, Productus Limestone Group. Part 4 Brachiopoda: India 

Geol. Survey Mem., Palaeont. Indica, srer. 13, v. 1, pt. 

4, p. 329-770, pl. 25-86. 

Weller, J. M., 1931, Mississippian fauna: Kentucky Geol. 

Survey, ser. 6, v. 36, p. 249-290, 12 pls., 1 fig. 

Weller, J. M., and others, 195·2, Geo,logy of the fluors.p•ar 

deposits of Illinois: Illinois. State GeoL Survey Bull. 76, 

147 p., 7 pls., 25 figs. 

Weller, Stuart, 1897, The Batesville Sandstone of Arkansas: 

New York Acad. Sci. Trans., v. 16, p. 251-282, pls. 19-21. 

--- 1910, Internal charaders of some Mississippian rhynchoneniform shells: Geol. Soc. America Bull., v. 21, p. 

497-516, 18 figs. 

--- 1911, Genera of Mississippian loop-hearing Brachiopoda: Jour. Geology, v. 19, no. 5, p. 439-448, 7 figs. 

--- 1914, The Missi.ssippian Brachiopoda of the Mississippi Valley basin: Illinois State Geol. Survey Mon. 1, 

508 p., atlas of 83 pis. 

--- 1920, The geology of Hardin County and the adjoining 

part of Pope County: Illinois State Geol. Survey Bull. 

41, 416 p., 11 pls., 3 figs. (with the collabo•ra.tion of 

Charles Butts, L. W. Currier, and R. D. Salisbury). 

White, C. A., 1877, Re:port upon the invertebrate fossils collected in portions of Nevada, Utah, Colorado, New 

Mexic.o, and Ari2lona by parties of the expeditions of 

1871, 1872, 1873, 1874: U.S. Geog. and Geot Survey 

west of lOOth Meridian (Wheeler), Paleontology, v. 

4, pt. 1, 219 p., 21 pls. 

--- 1884, The fossils of the Indiana rocks. No. 3: Indiana 

Dept. Geology and Nat. His,tory, Ann. Rept. 13, pt. 2, 

Paleontology, p. 107-180, pls. 23-39. 

Whitfield, R. P., 189'1, Contributions to invertebrate paleont!Ology [of Ohio]: New York Acad. Sci. Annals, v. 5, p. 

505-620, pls. 5-16, 2 figs. 

--- 1893, Contributions to invertebrate paleontology 

[of Ohio]: Ohio Geol. Survey Rept., v. 7, pt. 2, p. 407-

494, pls. 1-13, 2 figs. 

Woodruff, E. G., 1906, The geology of Cass County, Nebraska: 

Nebraska Geol. Su1·vey, v. 2, pt. 2, p. 171-302, 20 pls., 

33 figs. 

Worthen, A. H., 1860, Notice of a new spedes of Platycrinus 

and other fos.sils from the Mountain limestone of 

Illinois and Iowa; being an extract from the Second 

Annual Report of the Illinois Geological Survey: Acad. 

Sci. St. Louis Trans., v. 1, no. 4, p. 569-571. 
INDEX 

[Italic page numbers indicae both major references and descriptions] 

A 

Acrotretida 

Page 

D21 

Acrotretidina ------------------------- 21 

(Actinocyathus) stelcki, Lonsdaleia ____ 15 

adonis, Spirifer ----------------------- 70 

alternatus, Echinoconchus ------------43, 44 

altirostris, Schizophoria -------------- 23 

amsdenensis, Barytichisma ------------ 15 

Meekella -------------------------- 2, 24 

Multithecopora ------------------- 15 

Orthotetina __________ 2, 6, 12, 15, 16, 19, 

24, 27, 28; pl. 2 

amsdeniana, Carlinia ------2, 3, 6, 12, 15, 16, 

19, 42, 45; pl. 4 

Carlinia Subzone ------16, 17, 18, 21, 22 

62, 71, 77, 78 

Analysis of faunal relationships ------ 15 

Anthracospirifer ------------5, 13, 15, 65, 66 

birdspringensis ------------------ 74 

breckenridgensis ------------------ 73 

curvilateralis ----------15, 19, 66, 68, 75 

brutus ________ 6, 11, 15, 17, 66; pl. 11 

curvilateralis ____ 6, 11, 17, 65; pl. 11 

increbescens __________________ 65, 66, 74 

leidyi -------------------------- 72 

matheri -------------------------- 68 

occiduus __________ 6, 12, 13, 14, 15, 17, 210, 

67, 73, 74; pl. 11 

form A --------------------68; pl. 11 form B ____________________ 69; pl. 11 

opimus ---------------------------68, 72 

pellaensis ------------------------ 72 

rawlinsensis ____ 6, 13, 15, 17, 69; pl. 11 

rockymontanus ------------------- 68 

.~hawi ----------------------17, 19, 72, 73 

exoletus ------2, 3, 6, 12, 13, 14, 15, 

17, 71, 72, 74; pl. 12 

shawi --2, 6, 12, 15, 17, 70, 71; pl. 12 

shoshonensis ---------------------65, 70 

welleri --------------------17, 19, 73, 74 

lincolnensis __________ 6, 12, 13, 15, 17, 

73; pl. 13 

shawi Zone ------------16, 17, 19, 20 

welleri --------2, 3, 6, 12, 15, 17, 60, 

71, 72, 74; pl. 12 

sp ---------------------------------6, 14 

Antiq1latonia __________________ 5, 16, 46, 49 

antiquatus ------------------------ 48 

blackwelderi ________ 6, 13, 14, 15, 16, 20, 

46; pl. 5 

Zone ------------------------- 16 

coloradoensis ________ 6, 13, 14, 15, 16, 20, 

47; pl. 5 

hermosana ------------------------ 47 

pernodosa ----------------47, 48, 49, 52 

sp --------------------------6, 11, 15, 49 

antiquatus, Antiquatonia -------------- 48 

arizonensis, Buxtonia -----------------47, 48 

Articulata _ ___ _ _ _ __ _ __ __ _ _ __ ___ __ _ _ _ _ 22 

Athyridacea -------------------------- 55 

Athyrididae -------------------------- 5, 54 

Athyrididina -------------------------- 55 

Athyrids ----------------------------- 16 

Athyris subquadrata ------------------ 59 

a.trypoides, Cleiothyridina __________ 55, 56, 57 

Page 

saginata, Cleiothyridina ____ D6, 11, 12, 15, 

17, 55; pl. 7 

B 

Barytichisma amsdenensis ------------ 15 

bilobata, lnfiatia ---------------------- 37 

birdspringensis, Anthracospirifer ------ 74 

blackwelderi, Antiquatonia ___ 6, 13, 14, 15, 16, 

20, 46; pl. 5 

Antiquatonia Zone ---------------- 16 

Composita --------------1, 2, 75, 76, 77 

boonensis, Cancrinella ---------------- 3, 49 

Spirifer -------------------------- 67 Brachiopoda ______ --------- _ __ _ __ ___ __ 20 

Brachiopods, geographic and 

stratigraphic distribution _ _ 5 

zonal disllribution ----------------- 14 

Rrachythyrina -------------------1, 5, 74, 75 

washakiensis ______ 6, 11, 12, 15, 17, 74; 

pl. 13 

Brachythyris --------------------------74, 75 

bransonorum, Orthotetes 

kaskaskiensis ----2, 3, 6, 11, 12, 

15, 16, 29, 30, 31; pls. l, 2 

breckenridgensis, Anthracospirifer 73 

browni, Reticulariina ______ 2, 3, 6, 12, 13, 15, 

18, 19, 75; pl. 13 

Spiriferina ----------------------2, 75, 77 

brutus, Anthracospirifer 

curvilateralis ______ 6, 11, 15, 17, 

66; pl. 11 

Buxtonia arizonensis ----------------47, 48 

Buxtoniidae -------- ________ -------- ___ 5, 44 

c 

campestris, Spiriferina spinosa 3, 77 

Cancrinella boonensis ------------------ 3, 49 

Caninia nevadensis ------------------ 15 

sublamcllosa ---------------------- 17 

Zone ----------------11, 12, 16, 17, 19, 43 

carbonaria, Lingula ____ 4, 6, 12, 14, 16, 20 

Orthis ---------------------------- 23 

Rhipidomella ____ 6, 13, 15, 16, 23; pl. 1 

Carlinia ----------------------------5, 16, 42 

amsdeniana --------2, 3, 6, 12, 15, 16, 19, 

42, 45; pl. 4 

Subzone --------16, 17, 18, 21, 22, 62, 

71, 77, 78 

diabolica ------------------------- 42 

elegans -------------------------- 17 

phillipsi -------------------------- 43 

cestriensis, Diaphragmus ____ 6, 11, 15, 16, 19, 

39, 41, 510, 54, 55; pl. 4 

Productus ------------------------ 39 

Chaetetes wyomingensis -------------- 15 

chesterensis, Chonetes ---------------- 2 

Chonetacea ----------·--------------·--- 32 

Chonetes ----------------------------- 33 

chestcrensis ---------------------- 2 

choteauensis ---------------------- 33 

granulifer ------------------------ 33 

laevis ----------------------------32, 33 

pseudoliratus --------------------- 33 

sericius __ ------------------------ 33 

suttoni ---------------------------34, 35 

Page 

Chonetidae -------------------------- D5, 32 

Chonetidina -------------------------- 32 

Chonetids ---------------------------- 16 

choteauensis, Chonetes ---------------- 33 

Cleiothyridina ----------------------5, 16, 55 

atrypoides --------------------55, 56, 57 

saginata ____ 6, 11, 12, 15, 17, 55; pl. 7 

elegans ________________ 2, 6, 12, 57; pl. 7 

hirsuta --------------------------- 2, 57 

darwinensis ________ 3, 12, 15, 17, 56, 

57, 58; pl. 7 

orbicularis ________________________ 57, 58 

sublamellosa ______ 6, 11, 56, 57, 58; pl. 7 

sp ________ 3, 6, 13, 14, 56, 57, 58, 61, 62 

cochisensis, Spiriferina spinosa -------- 77 

Coledium ----------------------------- 5, 54 

explanatum ---------------------- 55 fragum ____________ 6, 11, 15, 16, 54; pl. 7 

obesum -------------------------- 55 

rhomboidale ---------------------- 55 

coloradoensis, Antiquatonia ____ 6, 13, 14, 15, 

16, 20, 47; pl. 5 

Dictyoclostus ---------------------- 47 

Productus ------------------------ 47 

injlatus ---------------------- 47 

Composita ________ 3, 4, 5, 11, 15, 17, 58, 59, 62 

blackwelderi ----------------2, 75, 76, 77 

elongata ______ 6, 13. 14, 15, 17, 64; pl. 10 

farrelli ---------------------------58, 59 

laevis ________ 6, 11, 15, 17, 58, 59; pl. 8 

ovata __________ 6, 13, 14, 15, 17, 20, 60, 

63, 64; pl. 10 

ozarkana ------------------------- 59 

poposiensis ____ 2, 3, 6, 12, 13, 15, 16, 17 

19, 60, 61, 63, 77; pls 8, 9 

Subzone ____ 16, 17, 18, 19, 21, 54, 62, 

72, 77, 78 

sigma ______ 2, 6, 12, 13, 14, 15, 17, 19, 

59, 64; pls. 8, 9 

subquadrata ______ 6, 11, 12, 15, 17, 19, 58, 

59, 63; pls. 8, 9 

subtilita ______ 6, 14, 15, 17, 62, 64; pl. 10 

ovata ----------------------3, 61, 62 

subtilita --------------------3, 61, 62 

trinuclea ---------------------- 3, 61 

sulcata ______ 3, 6, 12, 15, 17, 19, 59, 62; 

pl. 8 

trinuclea ------------------2, 59, 61, 62 sp ____________________ 3, 6, 11, 12, 13, 14 

Composition of the fauna ------------ 4 

conjluens, Dictyoclostus --------------- 39 

Inflatia -------------------------- 37 

costata, Eumetria --------------------18, 78 

Cranaena -----------------------------58, 78 

Cranaenidae ------------------------ 5, 78 

croneisi, Linoproductus ______________ 2, 49, 50 

Ovatia ____ 2, 3, 6, 12, 15, 49, 51, 52; pl. 6 

curvilateralis, Anthracospirifer ____ 15, 19, 66, 

68, 75 

A nthracospirifer 

curvilateralis __ 6, 11, 17, 65; pl. 11 

brutus, Anthracospirifer ____ 6, 11, 15, 17, 

66; pl. 11 

curvilateralis, 

Spirifcr 

Anthracospirifer ______ 6, 11, 17, 

65; pl. 11 

65 

D83 
D84 

Page 

D 

Darwin Sandstone Member D5 

darwinensis, Cleiothyridina 

hirsuta ____ 3, 12, 15, 17, 56; pl. 7 

Davidsoniacea ------------------------ 24 

decipiens, Mesolobus mesolobus -------- 33 

delira, Pulsia ______ 6, 14, 15, 16, 26, 27; pl. 2 

depressa, Schizophoria ____ 2, 4, 6, 11, 12, 13, 

14, 15, 16, 22, 23; pl. 1 

Derbyia --------------------5, 25, 27, 30, 31 

robusta ____ 6, 13, 14, 15, 16, 27, 81; pl. 2 

(Derbyia) sp, Orthotetes -------------- 30 

diabolica, Carlinia -------------------- 42 

Diaphragmus ------------------ 5, 16, 39, 42 

cestriensis _______ 6, 11, 15, 16, 19, 39, 41, 

5JO, 54, 55; pl. 4 

elegans -------------------------- 39 

fasciculatus ----------------------39, 41 

motesanae ------------------------ 39 

nivosus ____ 6, 11, 12, 15, 16, 19, 40; pl. 4 

phillpsi ------------------------ 2, 42, 45 

(Productus) elegans -------------- 39 

Dictyoclostidae ------------------------ 5, 46 

Dictyoclostus coloradoensis ---------- 47 

conjluens ------------------------ 39 in flatus _________________________ _47, 48 

portlockianus ------------------3, 36, 37 

Dielasmatacea ------------------------ 78 

Discinacea 21 

Discinidae ---------------------------- 5, 21 

drummondi, Pleurosiphonella ---------- 15 

duncanae, Duncanopora -------------- 15 

Dztncanopora duncanae ---------------- 15 

duodenaria, Ovatia --------------------50, 51 

E 

eastoni, Linoproductus ______ 6, 13, 14, 15, 20, 

51, 53; pl. 6 

Echinoconchidae ---------------------- 5, 43 Echinoconchus ______________ 5, 16, 43, 44, 45 

alternatus ------------------------43, 44 

vittatus -------------------------- 44 sp A ____________ 6, 13, 14, 15, 43; pl. 3 

elegans, Carlinia ---------------------- 17 Cleiothyridina __________ 2, 6, 12, 57; pl. 7 

Diaphragmus -------------------- 39 

(Productus) ------------------ 39 

Productus ------------------------39, 40 

elongata, Composita ______ 6, 13, 14, 15, 17, 

64; pl. 10 

Elythidae ---------------------------- 5, 65 

Enteletacea -------------------------- 22 

Enteletidae --------------------------- 5, 22 

Eolissochonetes --------------------5, 32, 33 

keyesi ----------------------------32, 33 

pseudoliratus ____ 4, 6, 12, 13, 14, 15, 16, 

20, 83, 34, 35; pl. 1 

Eolissochonetes suttoni ________ 6, 16, 34; pl. 1 

Eumetria ----------------------------- 5, 77 

costata --------------------------18, 78 

sulcata ______ 2, 3, 6, 12, 13, 14, 15, 18, 

77; pl. 13 

vereneuiliana ------------------2, 77, 78 

sp -------------------------------- 6, 11 

exoletus, Anthracospirifer 

shawi ______ 2, 3, 6, 12, 13, 14, 15, 

17, 71, 72, 74; pl. 12 

explanatum, Coledium ---------------- 55 

F 

farrelli, Composita --------------------58, 59 

fasciculatus, Diaphragmus ------------39, 41 

Productus -------------------- 30, 40, 41 

Faunal relationships analysis --------- 15 

Faunal succession interpretation ------ 18 

INDEX 

Page 

Flexaria ---------------------- D5, 16, 44, 45 

sp ------------ 2, 6, 12, 15, 44, 45; pl. 3 

Fossil localities ---------------------- 4 

fragum, Coledium ____ 6, 11, 15, 16, 54; pl. 7 

G 

genevievensis, Pustula ___________ 2, 42, 44, 45 

Geographic and stratigraphic distribution 

of the brachiopods ------ 5 

Girtyella ---------------------------5, 58, 78 

indianensis ______ 2, 6, 12, 18, 78; pl. 13 

globosa, Horridonia ------------------ 35 

Pustula -------------------------- 35 $coloconcha ______ 6, 14, 15, 20, 35; pl. 3 

gonionota, Reticulariina -------------- 77 

Spiriferina ---------------------- 3, 'J7 

granulifer, Chonetes ------------------ 33 

gregeri, Rhipidomella __________ 2, 72, 73, 78 

H 

hamatilis, Neokoninckophyllum --------13, 15 

hermosana, Antiquatonia ------------- 47 

hirsuta, Cleiothyridina ---------------- 2, 57 

darwinensis, Cleiothyridina __ 3, 12, 15, 17, 

56; pl. 7 

Horridonia globosa ------------------- 35 

Horseshoe Shale Member -------------- 11 

Inarticulata 20 

Inarticulates 16 

inconstans, Neokoninckophyllum ------ 13 

increbescens, Anthracospirifer ____ 65, 66, 74 

Spirifer --------------------------65, 66 

indianensis, Girtyella __ 2, 6, 12, 18, 78; pl. 13 

Scoloconclz a __________ ---------- __ _ 36 

lnjlatia ____________________ 5, 16, 36, 39, 48 

bilobata -------------------------- 37 

conjluens ------------------------ 37 

inflata ----------------------------37, 39 

lovei ________ 3, 6, 11, 12, 13, 15, 16, 19, 

36; pl. 3 

obsoleta -------------------------- 37 

spinolinearis ---------------------- 37 inflata, lnjlatia ________________________ 37, 39 

injlatus, Dictyoclostus ----------------47, 48 

Product1ts ------------------------ 47 

coloradoensis, Productus ---------- 47 

Interpretation of faunal succession ___ 18 

J 

Juresania __________________________ 5, 16, 45 

nebrascensis ---------------------- 45 

ovalis ---------------------------- 46 

symmetrica ---------------------- 46 sp ________________ 6, 13, 14, 15, 45; pl. 3 

K 

kas],askiensis, Orthotetes 2, 29 

bra.nsonorum, Orthotetes __ 2, 3, 6, 11, 12, 

15, 16, 29, 30, 31, pis. 1, 2 

keyesi, Eolissochonetes ----------------32, 33 

L 

laevis, Chonetes ----------------------32, 33 

Composita ____ 6, 11, 15, 17, 58, 59; pl. 8 

lata, Spiriferellina -------------------- 77 

leidyi Anthracospirifer ---------------- 72 

lincolnensis, Anthracospirifer 

welleri ______ 6, 12, 13, 15, 17, 

73; pl. 13 

Lingula ____________________________ 5, 16, 20 

Page 

carbonaria _____ D4, 6, 12, 14, 16, 20; pl. 1 

Lingulida ---------------------------- 20 

Lingulidae ------------------------5, 20, 21 

Lingulodiscina sp -------------------- 3, 21 

Linoproductid ------------------------ 6, 11 

Linoproductidae ---------------------- 5, 49 

Linoproductus ______________ 5, 16, 51, 52, 53 

croneisi ----------------------2, 49, 50 

eastoni ____ 6, 13, 14, 15, 20, 51, 53; pl. 6 

nodosus ---------------------------5!, 52 

planiventralis ____ 6, 13, 14, 15, 20, 52; 

pl. 5 

prattenianus --------------------3, 50, 51 

Lonsdaleia (Actinocyathus) stelcki ____ 15 

lovei, lnjlatia __________ 3, 6, 11, 12, 13, 15, 16, 

19, 36; pl. 3 

M 

Marginifcra muricatina ______________ 3, 42, 43 

sp ------------------------------- 3 

Ma.rginiferidae --------------------5, 16, 36 

Martinia ----------------------------2, 59, 60 

matheri, Anthracospirifer ------------ 68 

Meekella ------------------------------ 26 

amsdenensis ---------------------- 2, 24 

striaticostata ---------------------- 25 

Meekellidae ----------------------5, 16, 24 Mesolobus __________________ 5, 14, 16, 33, 35 

mesolobus ------------------------33, 35 

mesolobus decipiens -------------- 33 sp __________________ 6, 14, 15, 35; pl. 1 

mesolobus, Mesolobus ------------------33, 35 

decipiens, Mesolobus -------------- 33 

Mississippian and Pennsylvanian 

boundary relations 4 

Moffat Trail Limestone Member 5 

mosquensis, Pulsia -------------------- 26 

motesanae, Diaphragmus -------------- 39 

Multithecopora amsdenensis ---------- 15 

muralis, Ovatia __ 3, 6, 11, 12, 15. 50; 52; pl. 6 

muricatina, Marginifera ____________ 3, 42, 43 

N 

nebrascensis, Juresania -------------- 45 

Neochonetes -------------- ----------. 33 Neokoninckophyllum hamatilis ________ 13, 15 

hamatilis Zone ------------------ 16 

inconstans ------------------------ 13 

Neospirifer --------------------------- 5, 15 

praenuntius ______ 6, 11, 15, 17, 75; pl. 13 

nevadensis, Caninia ------------------ 15 nivalis, Rugoclostus __________ 37, 39, 43, 44 

nivosus, Diaphragmus ______ 6, 11, 12, 15, 16, 

19, 40; pl. 4 

nodosus, Linoproductus ---------------51, 52 

norwoodana, Reticulariina ------------ 77 

norwoodanus, Spirifer ---------------- 77 

0 

obesum, Coledium -------------------- 55 

obsoleta, lnflatia -------------------- 37 

occidentalis, Spirifer ---------------- 67 

Spirifer opimus ----------------- 67 

occiduus, Anthracospirifer __ 6, 12, 13, 14, 15, 

17, 20, 67, 73, 74; pl. 11 

form A, Anthracospirifer ____ 68; pl. 11 

form B, Anthracospirifer ______ 69; pl. 11 

Spirifer -------------------------- 67 

oldahomae, Schizophoria -------------- 23 

opimus, Anthracospirifer --------------68, 72 

Spirifer ------------------3, 12, 71, 72 

occidentalis, Spirifer -------------- 67 

orbicularis, Cleiothyridina ------------57, 58 

Orbiculoidea ----------------------3, 16, 21 
Page 

wyomingensis _______ D2, 6, 12, 14, 15, 16, 

21, 22; pl. 1 

sp A ________ 3, 6, 12, 15, 16, 21, 22; pl. 1 

sp B ------------6, 13, 15, 16, 21; pl. 1 

Orthids ------------------------------ 16 

Orthida ------------------------------ 22 

Orthidina ---------------------------- 22 

Orthis carbonaria -------------------- 23 

pecosi ---------------------------- 23 

robusta --------------------------- 31 Orthotetes ______________ 5, 16, 29, 30, 31, 32 

kaskaskiensis --------------------- 2, 29 

bransonorum ------2, 3, 6, 11, 12, 15, 

16, 29, 30, 31; pls. 1, 2 

robusta --------------------------- 32 

(Derbyia) sp ---------------------- 30 

(Orthotetes) sp ------------------29, 30 

sp A __________ 6, 13, 14, 15, 16, 30; pl. 2 

sp ________ 3, 6, 11, 15, 16, 29, 31; pl. 2 

(Orthotetes), Orthotetes sp ------------29, 30 

Orthotetidae ----------------------5, 16, 29 

Orthotetina ---------------------- 5, 24, 28 

amsdenensis ------2, 6, 12, 15, 16, 19, 24, 

27, 28; pl. 2 

Orthotetoids ____________ 6, 11, 12, 13, 14, 16 

osagensis, Wellerella ------------------53, 54 

ottumwa, Pugnoides -------------- 2, 53, 54 

ovalis, Juresania ---------------------- 46 

ovata, Composita ______ 6, 13, 14, 15, 17, 20, 

60, 63, 64; pl. 10 

Composita subtilita ------------3, 61, 62 

Ovatia ----------------------------15, 16, 49 

croneisi __ 2, 3, 6, 12, 15, 49, 51, 52; pl. 6 

duodenaria -----------------------50, 51 

muralis ______ 3, 6, 11, 12, 15, 50, 52; pl. 6 

Overtoniidae -------------------------- 5, 35 

ozarkana, Composita ------------------ 59 

p 

pecosi, Orthis ------------------------ 23 

Rhipidomella --------------------- 23 

pellaensis, Anthracospirifer ---------- 72 

Spirifer ----------------------2, 70, 71 

pernodosa, Antiquatonia ______ 47, 48, 49, 52 

phillipsi, Carlinia -------------------- 43 

Diaphragmus --------------------2, 42, 45 

planiventralis, Linoproducttts ____ 6, 13, 14, 15, 

20, 52; pl. 5 

Pleurosiphonella drummondi ---------- 15 

Joposiensis, Composita ----2, 3, 6, 12, 13, 15, 

16, 17, 19, 60, 61, 63, 77; pis. 8, 9 

Composita Subzone ____ 16, 17, 18, 19, 21, 

54, 62, 72, 77, 78 

Schuchertella ------2, 6, 12, 13, 15, 16, 19, 

28; pls. 1, 2 

Streptorhynchus ----------------- 2, 28 

portlockianus, Dictyoclostus ________ 3, 36, 37 

praenuntius, Neospirifer ____ 6, 11, 15, 17, 75; 

pl. 13 

prattenianus, Linoproductus --------3, 50, 51 

Productacea -------------------------- 35 

Productidae ------------------------5, 16, 39 

Productidina -------------------------- 35 Productoids ________________________ 6, 12, 16 

Productus cestriensis ---------------- 39 

coloradoensis -------------------- 47 

elegans ---------------------------39, 40 

fasciculatus --------------------39, 40, 41 

in/latus -------------------------- 47 

coloradoensis ----------------- 47 

semistriatus ---------------------- 38 

(Productus) elegans, Diaphragmus ____ 39 

pseudoliratus, Chonetes ---------------- 33 

Eolissochonetes _____ _4, 6, 12, 13, 14, 15, 

16, 20, 33, 34, 35; pl. 1 

Rugosochonetes ------------------- 52 

Pugnoides ---------------------------- 5, 53 

ottumwa ------------------------2, 53, 54 

INDEX 

Page 

quinqtteplecis _________ D2, 3, 4, 12, 13, 15, 

16, 53, 79; pl. 7 

Pulsia ------------------------------1, 5, 25 

delira __________ 6, 14, 15, 16, 26, 27; pl. 2 

mosquensis ----------------------- 26 

sp A __ 6, 11, 13, 15, 16, 26, 27, 28; pl. 2 

sp -------------------------------- 25 

(Pulsia), Schellwienella ----------------25, 26 

Pustula genevievensis __________ 2, 42, 44, 45 

globosa --------------------------- 35 

Q 

quinqueplecis, Pugnoides ____ 2, 3, 4, 6, 12, 13, 

15, 16, 53, 79; pl. 7 

R 

Ranchester Limestone Membw 13 

rawlinsensis, Anthracospirifer __ 6, 13, 15, 17, 

69; pl. 11 

resupinoides, Schizophoria ------------ 23 

Retichonetes -------------------------- 33 

Reticularia setigera ------------------ 65 

setigerus ------------------------- 65 

Reticulariacea ------------------------ 65 

Reticulariina ------------------------- 75 

browni ______ 2, 3, 6, 12, 13, 15, 18, 19, 

75; pl. 13 

gonionota ------------------------ 77 

norwoodana ---------------------- 77 

spinosa --------------------------75, 77 

sp -------------------------------- 6, 11 

Retziacea ---------------------------- 77 

Retziidae ----------------------------- 5, 77 

Retziidina ---------------------------- 77 

Retziids and Terebratuloids ------------ 18 

Rhipidomella -------------------------- 5, 23 carbonaria ______ 6, 13, 15, 16, 23; pl. 1 

gregeri --------------------2, 72, 73, 78 

pecosi --------------------------- 23 

Rhipidomellidae ---------------------- 5, 23 

rhomboidale, Coledium ---------------- 55 

Rhynchonellacea ---------------------- 53 

Rhynchonellida ----------------------- 53 

Rhychonelloids ------------------------ 16 

robusta, Derbia ______ 6, 13, 14, 15, 16, 27, 31; 

pl. 2 

Orthis ---------------------------- 31 

Orthotetes ------------------------ 32 

rockymontanus, Anthracospirifer ------ 68 

Rugoclostus --------------------5, 16, 37, 38 nivalis __________________ 37, 39, 43, 44 

semistriatus ---------------------- 39 

williamsi --------------6, 13, 15, 38; pl. 3 

Rugosochonetes ----------------------- 33 

pseudoliratus 52 

s 

saginata, Cleiothyridina 

atrypoides ______ 6, 11, 12, 15, 17, 

55; pl. 7 

salemensis, Spiriferina ---------------- 77 

Schellwienella ------------------------ 26 

(Pulsia) --------------------------25, 26 

Schizophoria --------------------5, 16, 22, 23 altirostris __ ---- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 23 

depressa ______ 2, 4, 6, 11, 12, 13, 14, 15, 

16, 22, 23; pl. 1 

oklahomae ------------------------ 23 

resupinoides ---------------------- 23 

schucherti ----------------------- 23 

swallovi -------------------------- 2, 22 

texana ___ _4, 6, 12, 14, 15, 16, 22; pl. 1 

Schuchertella ----------------------5, 26, 28 

poposiensis ______ 2, 6, 12, 13, 15, 16, 19, 

28; pls. 1, 2 

Schuchertellidae ---------------------- 5, 28 

D85 

Page 

schucherti, Schizophoria ------------- D23 

Scoloconcha -------------------------5, 16, 35 

globosa __________ 6, 14, 15, 20, 35; pl. 3 

indianensis ---------------------- 36 

Selenella ------------------------------ 5, 78 

walteri ---------------2, 6, 53, 54, 78 

Seminula subquadrata ---------------- 59 

subtilita ------------------------- 64 

semistriatus, Productus ---------------- 38 

Rugoclostus ---------------------- 39 

sericius, Chonetes -------------------- 33 

setiger, Torynifer ______ 6, 12, 18, 65; pl. 13 

setigera, Reticularia ------------------ 65 

Spirifera ------------------------- 65 

Torynifer ------------------------ 65 

setigerus, Reticularia ------------------ 65 

Spirifer ------------------------- 65 

shawi, Anthracospirifer ----17, 19, 72, 73 

Anthracospirijer shawi ____ 2, 6, 12, 15, 

17, 70, 71; pl. 12 

welleri Zone ________ 16, 17, 19, 20 

exoletus, Anthracospirifer __ 2, 3, 6, 12, 13, 

14, 15, 17, 71, 72, 74; pl. 12 

shawi, Anthracospirifer ----2, 6, 12, 15, 

17, 70, 71; pl. 12 

shoshonensis, Anthracospirifer --------65, 70 

Spirifer --------------------2, 65, 68, 75 

sigma, Composita ______ 2, 6, 12, 13, 14, 15, 

17, 19, 59, 64; pis. 8, 9 

spinolinearis, lnfiatia ---------------- 37 

spinosa, Reticulariina -----------------75, 77 

campestris, Spiriferina ----------- 3, 77 

cochisensis, Spiriferina ---------- 71 

spinosus, Spirifer -------------------- 77 

Spirifer adonis ----------------------- 70 

boonensis ------------------------ 67 

curvilateralis ---------------------- 65 

increbescens ----------------------65, 66 

norwoodanus --------------------- 77 

occidentalis ----------------------- 67 

occiduus -------------------------- D67 opimus __________________ 3, 12, 71, 72 

occidentalis ------------------ 67 

pellaensis --------------------2, 70, 71 

setigerus ------------------------- 65 

shoshonensis ----------------2, 65, 68, 75 

spinosus ------------------------- 77 

welleri ----------------2, 3, 12, 72, 73 

sp ------------------------------- 3, 71 

Spirifera setigera --------------------- 65 

Spiriferacea -------------------------- 65 

Spiriferellina lata -------------------- 77 Spiriferida ____________ ;..______________ 55 

Spiriferidae ----------------------5, 17, 65 

Spiriferidina ------------------------- 65 

Spiriferids --------------------------- 17 

Spiriferina --------------------------- 77 

browni ------------------------2, 75, 77 

gonionota ------------------------ 3, 77 

salemensis ------------------------ 77 

spinosa campestris ---------------- 3, 77 

cochisensis ------------------- 77 

subspinosa ----------------------- 77 

Spiriferinacea ------------------------ 75 

Spiriferinidae ------------------------ 5, 18 

stelcki, Lonsdaleia ( Actinocyathus) ____ 15 

Stenoscismatacea --------------------- 54 

Stenoscismatidae 

Stratigraphic and geologic distribution 

of the brachipods --------

Streptorhynchus __ --------------------

poposiensis ----------------------

striaticostata, Meekella ----------------

Strophomenida -----------------------

Strophomenidina 

5, 54 

5 

28 

2, 28 

25 

24 

24 

subcttneata, Tetracamera -------------- 2 

sublamellosa, Caninia ------------- 17 

Cleiothyridina ____ 6, 11, 56, 57, 58; pl. 7 

subquadrata, Athyris ----------------- 59 
D86 

Page 

Composita _____ D6, 11, 12, 15, 17, 19, 58, 

59, 63; pls. 8, 9 

Seminula 59 

subspinosa, Spiriferina --------------- 77 

subtilita, Composita ______ 6, 14, 15, 17, 62, 

64; pl. 10 

Composita subtilita ____________ 3, 61, 62 

ovata, Composita ______________ 3, 61, 62 

subtilita, Composita ____________ 3, 61, 62 

trinuclea, Composita -------------- 3, 61 

Seminula ------------------------ 64 

Terebratula ---------------------- 64 

sulcata, Composita ____ 3, 6, 12, 15, 17, 19, 59, 

62; pl. 8 

Eumetria ______ 2, 3, 6, 12, 13, 14, 15, 18, 

rr; pl. 13 

suttoni, Chonetes --------------------34, 35 

Eolissochonetes ________ 6, 16, 94; pl. 1 

swallovi, Schizophoria ---------------- 2, 22 

symmetrica, Juresania ---------------- 46 

INDEX 

Tercbratula subtilita 

Terebratulida 

Terebratulidina 

T 

Page 

D64 

78 

78 

Tetracamera sttbcuneata -------------- 2 

tcxana, Schizophoria _______ _4, 6, 12, 14, 15, 

16, 22; pl. 1 

Torynifer --------------------------5, 57, 65 setiger ____________ 6, 12, 18, 65; pl. 13 

setigera -------------------------- 65 trinuclea, Composita ____________ 2, 59, 61, 62 

Composita subtilita --------------- 3, 61 

v 

verneuiliana, Eumetria ______________ 2, 77, 78 

vittatus, Echinoconchus -------------- 44 

w 

walteri, Selenella __________ 2, 6, 53, 54, 78 

washakiensis, Brachythyrina ____ 6, 11, 12, 15, 

17, 74; pl. 13 

Page 

Wellerella osagensis ----------------- D53, 54 

sp. A ---------------------------- 54 

sp. B ---------------------------- 54 

sp ------------------------------- 54 welleri, Anthracospirifer ______ 17, 19, 73, 74 

Anthracospirifer welleri ______ 2, 3, 6, 12, 

15, 17, 60, 71, 72, 74; pl. 12 

lincolnensis, 

Anthracospirifer __ 6, 12, 13, 15, 

17, 79; pl. 13 

welleri, Anthracospirifer __ 2, 3, 6, 12, 15, 

17, GO, 71, 72, 74; pl. 12 

Spirifer ----------------2, 3, 12, 72, 73 

welleri-shawi, Anthracospirifer 

Zone ______________ 16, 17, 19, 20 

williamsi, Rugoclostus ____ 6, 13, 15, 98; pl. 3 

wyomingensis, Chaetetes -------------- 15 

Orbiculoidea ______ 2, 6, 12, 14, 15, 16, 

21, 22; pl. 1 

z 

Zonal distribution of the brachiopods 14 
PLATES 1-13 

Contact photographs of the plates in this report are available at cost, from the U.S. 

Geological Survey Library, Federal Center, Denver, Colorado 80225. 
FIGURES 

PLATE 1 

[Figures natural size unless otherwise indicated on plate] 

1-3, 6. Lingula cf. L. carbonaria Shumard (p. D20). 

1. Enlarged view of specimens, USNM 163703A, from Horseshoe Shale Member, collection 46. 

2, 3. Exterior view and enlarged view of specimen, USNM 163704, from Ranchester Limestone 

Member, collection 139. 

6. Exterior view of another specimen, USNM 163703B, collection 46. 

4, 5, 10. Orbiculoidea sp. A (p. D21). 

4, 5. Exterior and side views of pedicle valve with nearly marginal apex, UW IT-185, from Horseshoe Shale Member, collection 21. 

10. Pedicle valve with apex slightly farther from margin, UW IT-184, collection 21. 

7, 8. Orbiculoidea sp. B. (p. D21). 

Enlarged pedicle and side views of spedmen, USNM 163706, from Ranchester Limestone Member, 

collection 3. 

9, 11-16. Orbiculoidea wy01ningensis BI'anson and Greger (p. D21). 

From Horseshoe Shale Member. 

9. Pedicle valve of paralectotype, UM 2641, collection 36a. 

11-13. Enlarged brachial and pedicle views and brachial view of nearly complete specimen, 

USNM 163705, collection 38. 

14-16. Enlarged brachial and pedicle views and brachial view of lectotype, UM 2641, collection 

36a. 

17-19. Sc,hizophoria depressa Easton (p. D22). 

Enlarged pedicle, brachial, and side views of specimen, USNM 163707, from Horseshoe Shale 

Member, collection 45. 

20-25. Rhipidonwlla carbonaria (Swallow) (p. D23). 

From Ranchester Limestone Member, collection 86. 

20, 24. Views of pedicle valve interior, USNM 163718. 

21, 23. Views of pedide valve exterior, USNM 163717. 

22, 25. Side views of specimen, U SNM 16·3716. 

26-30, 40, 41. Schizophoria aff. S. texana Girty (p. D22). 

From Ranchester Limestone Member. 

26-30. Side, brachial, anterior, posterior, and pedicle views of well-preserved specimen, USNM 

163713, collection 68. 

40, 41. Enlarged views of apical region of brachial valve, USNM 167315, and of pedicle valve, 

USNM 167314, collection 67. 

31-34. Mesolobus sp. (p. D35). 

31, 32. Enlarged exterior and anterior views of pedicle valve, USNM 163746, from Ranchester 

Limestone Member, collection 15. 

33, 34. Enlarged exterior and anterior views of another pedicle valve, USNM 163747, collection 15. 

35-39. Eolissochonetes? suttoni (C. Branson) (p. D34). 

Enlarged pedicle view and posterior, side, pedicle, and brachial views of holotype and only known 

example, UM 6832, from Horseshoe Shale Member, collection 36d. 

42-50, 52. Eolissochonetes pseudoliratus (Easton) (p. D33). 

From Hors·e1shoe Shale Member, collection 157. 

42, 43. Enlarged pedicle and brachial views of fairly complete specimen, USNM 163742. 

44. Enlarged view of interior of brachial valve, USNM 163744. 

45, 46. Enlarged pedicle and brachial views of a narrower specimen, USNM 163741. 

47. Enlarged view of brachial valve interior, USNM 163475. 

48. Enlarged view of interarea of another specimen, USNM 163740. 

49, 50. Enlarged brachial and pedicle views of another shell, USNM 16.3739. 

52. Enlarged view of interior of pedicle valve USNM 163743. 

51, 53. Schuchertella cf. S. poposiensis (C. Branson) (p. D28). 

51. Enlarged interior view of brachial valve showing details of ca!'dinal process, USNM 163727, 

from Horseshoe Shale Member, collection 69. 

53. Enlarged view showing interior of pedicle valve, USNM 163709, collection 69. 

54. Orthotetes ka,skaskiensis bransonorum n. subsp. (p. D29). 

Exterior of incomplete but well-preserved pedicle valve, USNM 163729, from Horseshoe Shale 

Member, collection 27. 
GEOLOGICAL SU RVEY PROFESSIONAL PAPER 848-D PLATE I 

11 

4 

7 10 

12 

X2 

8 13 16 

1~ 

25 29 

17 21 23 27 

!1 I . , , .; J. ,· . ' ' 

X2 

24 28 

22 26 30 

38 

35 

39 

32 X2 

34 36 37 

48 X2 

42 45 

43 46 

49 

44 47 50 52 

LINGULA, ORBICULOIDEA , SCHIZOPHORIA, RHIPIDOMELLA, MESOLOBUS, 

EOLISSOCHONETES, SCHUCHERTELLA, AND ORTHOTETES 
PLATE 2 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-3, 7. Orthotetina amsdenensis (Branson and Greger) (p. D24). 

1-3. Brachial, side, and pedicle views of lectotype, UM 2643, from Horseshoe Shale Member, collection 36b. Umbonal region of pedicle valve ground down slightly. 

7. Brachial view of paralectotype, UM 2643, collection 36b. 

4-6. Pulsia sp. A (p. D27). 

Pedicle, side, and brachial views of eroded specimen, USNM 163719, from Moffat Trail Limestone 

Member, collection 72. 

8-10,12-17. Schuchertella poposiensis (C. Branson) (p. D28). 

From Horseshoe Shale Member. 

8, 9, 15. Enlarged brachial and side vie·ws of brachial view of hypotype, USNM 163740, collection E. 

10, 16, 17. Enlarged brachial view, brachial view, and enlarged posterior view of another 

hypotype, USNM 163739, collection E. 

12-14. Enlarged pedicle, posterior, and brachial views of C. Branson's largest paratype, UM 

6833, collection 36d. 

11, 18. Orthotetes sp. (p. D31). 

A unique specimen, USNM 163730, from Moffat Trail Limestone Member, collection 93. 

19-21. Orthotetes sp. A (p. D30). 

From Horseshoe Shale Member. 

19. View of brachial valve, USNM 163732, collection 54. 

20. View of pedicle valve, USNM 163731, collection 54. 

21. Enlarged oblique view showing interarea of fairly complete specimen, USNM 163733, collection 53. 

22-26, 32. Pulsict de lira n. sp. (p. D26). 

From Ranchester Limestone Member, collection 52. 

22. Pedicle valve preserved in fine sandstone, a paratype, USNM 163722. 

23, 32. Posterior and ventral views of another pedicle valve, the holotype, USNM 163721. 

24-26. Side, dors~l, and posterior views of brachial valve, a paratype, USNM 163724. 

27-29. Orthotetes kaskaskiensis bransonorum n. subsp. (p. D29). 

From Horseshoe Shale Member. 

27, 28. Posterior (showing interarea) and brachial views of holotype, UM 2642a, collection 36a. 

29. Enlarged view of interarea of pedicle valve and apical part of brachial valve, USNM 

163728, coi!ection 27. 

30, 31,33-35. Derbyia cf. D. ro·busta (Hall) (p. D31). 

From Horseshoe Shale Member. 

30. View of pedicle valve, USNM 163737, collection 2. 

31. View of ped.icle valve, USNM 163734, collection 3. 

33. Partly oblique enlarged view of posterior part of brachial valve showing cardinal process, 

USNM 163736, collection 3. 

34, 35. Dorsal and side views of brachial valve, USNM 163735, collection 3. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-D PLATE 2 

7 8 9 

14 

15 

16 

32 33 34 

ORTHOTETINA, PULSIA, SCHUCHERTELLA, ORTHOTETES, AND DERBY/A 
FIGURES 

PLATE 3 

[Figures natural size unless otherwise indicated on plate] 

1-9. lnfiatia lovei n. sp. (p. D36). 

From Horseshoe Shale Member, collection 47. 

1. Interior of pedicle valve, paratype, USNM 163750, showing adductor muscle-scar platform. 

2-4. Enlarged side and po·s.terior views and dorsal view of brachial valve, paratype, USNM 

163751. 

5. Two brachial valve interiors on slab, paratypes, USNM 163752a, b. 

6-9. Both sides, posterior, and ventral views of pedicle valve, holotype, USNM 163749. 

10-16, 18. Rugoclostus williamsi n. sp. (p. D38). 

From Ranchester Limestone Member. 

10-12. Posterior, side, and ventral views of pedicle valve, holotype, USNM 163754, collection 100. 

13, 14. Side and ventral views of p·edicle valve, paratyp·e, USNM 163755, collection 100. 

15, 16, 18. Anterior, ventral, and side views of external mold of brachial valve, paratype 

USNM 163757, collection 100. In figure 15, tiny black dots mark bases of exte•rnal spines. 

17. Rugoclostus cf. R. williamsi n. sp.(p. D39). 

19, 23, 24, 31, 32. 

20-22. 

25-27. 

Latex cast of small pedicle valve, USNM 167719, from Ranchester Limestone Member, collection 

83. 

Echinoconc.hus sp. A (p. D43). 

From Horseshoe Shale Member. 

19. Latex cast showing interior of brachial valve, USNM 163789, collection 1. 

23, 24, 31, 32. Pedicle, side, brachial, and oppo·site side views of nearly complete specimen, 

USNM 163788, collection 5. 

Scolonconcha globosa (Mather) (p. D35). 

Ventral view and enlarged ventral and side views of pedicle valve, USNM 163790, from Ranchester Limes-tone Member, collection 13. 

JuTesa.nia sp. (p. D45). 

25. Latex cast o·f brachial valve interior, USNM 163771, from Ranchester Limestone Member, 

collection 142. 

26, 27. Ventral and side views of pedicle valve, USNM 163772, from Horseshoe Shale Member, collection 54. 

28-30. FlexaTia sp. (p. D44). 

Posterior, ventral, and side views of pedicle valve, UM 2646, from Horseshoe Shale Member, 

collection 36a. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848- D PLATE 3 

8 

4 5 

9 

3 X2 

12 13 14 

15 16 

17 

22 

25 

28 

23 31 

29 

27 

INFLATIA, RUGOCLOSTUS, ECHINOCONCHUS,SCOLOCONCHA, JURESANIA, AND FLEXARIA 
PLATE 4 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-4, 15- 20, 22. Diaphragmus cestriensis (Worthen) (p. D39). 

From Moffat Trail Limestone Member. 

1-4. Posterior, ventral, anterior, and side views of pedicle valve, USNM 163764, collection 

121. 

15-18. Enlarged side view and posterior, ventral, and side views of pedicle valve, USNM 

163766, collection 122. 

19. Enlarged view of latex cast showing brachial valve interior, USNM 163765, coiiection 121. 

20, 22. Top views of partly decorticated visceral disc of brachial valve showing diaphragm, 

USNM 163710, coiiection 122. 

5-14. Diaphmgmus nivosus n. sp. (p. D40). 

5, 6, 12-14. Posterior, anterior, side, and ventral views and view of diaphragm area of holotype, 

USNM 163758, from Heath Formation, USGS collection 13425-PC, Big Snowy Mountains, 

Mont. 

7. Latex cast of exterior of brachial valve, USNM 163759, paratype from type locality. 

8-10. Posterior, ventral, and side vi ews of fairly complete pedicle valve, USNM 163768, from 

Horseshoe Shale Member, collection 41. 

11. View of brachial valve, showing diaphragm, USNM Hi3769, coilection 41. 

21, 23-37. Carlinia amsdeniana Gordon (p. D42). 

F r om Horseshoe Shale Member. 

21, 23. Enlarged view of brachial valve interior preserved in fine sandstone and view of exterior of same valve, UW A11094, collection 31. 

24, 25. Enlarged views of latex casts of pedicle valve interior and brachial valve interior 

from same internal mold, USNM 163762, paratype, collection 27. 

26-29. Side, posterior, anterior, and ventral views of pedicle valve, UW A11119, collection 28. 

30, 31, 34- 37. Side, posterior, enlarged posterior, pedicle, brachial, and enlarged side views of 

holotype, UM 2645, collection 36a. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848- D PLATE 4 

8 

12 

2 

6 

13 

3 17 

4 

7 

11 14 18 

Xl~ 

19 

20 

X 1~ 22 

21 

24 

28 29 

26 

25 30 31 33 

34 35 36 

DIAPHRAGMUS AND CARLIN/A 
PLATE 5 

[Figures natural size unless otherwise indicated on p.late] 

FIGURES 1-9. Antiquatonia cf. A. coloradoensis (Girty) (p. D47). 

1-3. Posterior, ventral, and side vi·ews of a worn pedicle valve, USNM 163783, from Ranchester Limestone Member, collection 6. 

4. Latex caSit showing interior of pedicle valve with adductor muscle-scar platform, USNM 163785, 

fNm Horseshoe Shale Member, collection 53. 

5. Latex cast crudely showing part of brachial valve interior, USNM 163784, from Ranchester Limestone Member, collection 6. 

6-9. Posterior, side, pedicle, and anterior views of shell having pathologic median fold on anterior slope, 

USNM 163782, from Ranchester Limestone Member, collection 13. 

10-19. Antiquatonia blackwelderi n. sp. (p. D46). 

From Ranchester Limestone Member. 

10. Latex cast showing interior of pedicle valve and its musculature, paratype, USNM 163777, collection 83. 

11. Latex cast showing interior of pedicle valve of another paratype, USNM 163780, collection 131. 

12-14. Posterior and both sides of ho,lotype, USNM 163774, coUection 133. 

15. Latex cast showing part of brachial valve interior, paratype, USNM 163779, collection 131. 

16. Latex cast showing exterior of brachial valve, paratype, USNM 163775, collection 133. 

17. Large crushed pedicle valve, paratype, USNM 163776, coUection 139. 

18, 19. Latex casts showing interior and exterior of the s'ame brachial valve, paratype, USNM 163778, 

collection 130. 

20-25. Linop1·oductus planiventmlis Hoare (p. D52). 

From Horseshoe Shale Member, collection 3. 

20, 25. Pos,terior view and enlarged posterior view of pedicle valve, USNM 167716. 

21, 22. Ventral and side views of pedicle valve, USNM 167715. 

23, 24. Interior views of partly decorticated brachial valve showing cardinal process, USNM 167718. 
GEOLOGICAL SURVEY 

1 

10 

22 

3 

4 7 

23 

24 

ANTIQUATONIA AND LINOPRODUCTUS 

PROFESSIONAL PAPER 848-D PLATE 5 

15 

16 
PLATE 6 

[Figures natu1·al size unless otherwise indicated on plate] 

FIGURES 1- 6. Ovatia croneisi (C. Branson) (p. D49). 

From Horseshoe Shale Member. 

1-3. Posterior, ventral, and side views of a nearly complete pedicle valve, UW A1281, hypotype collection 31. 

4-6. Enlarged posterior, pedicle and brachial views of holotype, UM 6831, an immature s.pecimen, collection 36d. 

7-17. Ovatia muralis n. sp. (p. D50). 

7-10. Enlarged posterior, pedicle, and side views and pedicle view of immature pedicle valve, USNM 

163792, from Moffat Tra.il Limestone Member, collection 93. 

11-14. Posterior, pedicle, and side views and enlarged pedicle view of specimen USNM 163795, from 

Hors.eshoe Shale Member, collection 45. 

15-17. Posterior, pedicle, and side views of holotype, USNM 163791, pedicle valve, having anteroventral 

part restored, from Moffat Trail Limestone Member, collection 93. 

18-31. Linoproductus eastoni n. sp. (p. D51). 

18, 28. Pedicle and side views of paratype, USNM 163801, from Horseshoe Shale Member, collection 53. 

19-21. Interior, anterior, and side views of well-preserved brachial valve with parts of pedicle valve 

adhering, holotype, USNM 163796, from uppermost Cameron Creek Member of the Tyler Formation or 

lowermost Alaska Bench Limestone, USGS collection 16177-PC, Big Snowy Mountains, Mont. 

22, 23, 27. Anterior, side, and interior, partly decorticated, views of similar brachial valve, USNM 

163800, from Horseshoe Shale Member, collection 54. 

24-26. Pedicle, side, and posterior views of pedicle valve, paratype, USNM 163797, from type locality. 

29-31. Pedicle, anterior, and side views of incomplete specimen exposing visceral disk of brachial valve 

and possessing weak median fold in pedicle valve, paratype, USNM 163798, from type localty. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848- D PLATE 6 

X2 

1'····-

.!1._ ......... .,_ ... -";:-' 

OV AT/A AND LJNOPRODUCTUS 
PLATE 7 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-5, 32-36. Coledium fragum n. sp. (p. D54). 

From Moffat Trail Limestone Member, collection 93. 

1-4. Enlarged brachial, anterior, side, and pedicle views of holotype, USNM 167730. 

5. Enlarged brachial view of paratype, USNM 167731. 

32-36. Enlarged brachial, anterior, side, pedicle, and posrterior views of an immature 

paratype, USNM 167732. 

6-30. Pugnoides quinqueplecis (Easton) (p. D53). 

From Horseshoe Shale Member, unless otherwise noted. 

6-9. Enlarged anterior, brachial, side, and pedicle views of specimen having five 

costae on fold, USNM 167725, coUection 38. 

10, 11. Enlarged anterior and brachial views of another specimen, having three 

costae on fold, USNM 167726, collection 38. 

12-16. Enlarged brachial, anterior, side, posterior, and pedicle views of specimen 

having four costae on fold, USNM 167721, collection B. 

17, 18. Enlarged views of interior of pedicle valve articulated with perforated hinge 

plate of brachial valve, USNM 167723, collection 69. 

19-23. Enlarged anterior, brachial, side, pedicle, and posterior vie.ws of another 

spe·cimen having five costae on fold, USNM 167722, coUection D. 

24. Enlarged view of interior of brachial valve to which adhere several silicified 

pellets, USNM 167724, from collection 69. 

25-30. Enlarged brachial, anterior, s:ide, posterior, and pedicle views and brachial 

view of sort subtriangular variant, USNM 167720 from Ranches.ter Limestone 

Member, collection 82. 

31, 38- 40, 42-45, 58, 59. Cleiothyridina hirsuta darwinensis n. subsp. (p. D56). 

From Horseshoe Shale Member. 

31, 42-45. Brachial view and enlarged brachial, posterior, side, and pedicle views of 

holotype, USNM 168391, from coUection 137. 

38-40. Enlarged pedicle, side, and brachial views of paratype, UM 6623, from collection 36e 

58, 59. Enlarged anterior and brachial views of weathered specimen, USNM 168393, 

from collection 27. 

37. Cleiothyriclina aff. C. sublamellosa (Hall) (p. D58). 

Enlarged ventral view of pedicle valve, USNM 168453, from Moffat Trail Limestone 

Member, collection 93. 

41,50- 53. Cleiothyridina aff. C. elegans Girty (p. D57). 

Brachial view and enlarged side, pedicle brachial and anterior views of specimen figured 

by Branson and Greger ( 1918, pl. 19, fig. 14) as C. hi1·suta (Hall), UM 2654, from 

Horseshoe Shale Memb:er, collection 36a. 

46-49. Cleiothyridina hirsuta darwincnsis n. subsp.? (p. D56). 

Enlarged side, pedicle, brachial, and anterior views of specimen replaced by chert, USNM 

168452, from Horseshoe Shale Member, collection A. 

54-57. Cleiothyridina atrypoides saginata n. subsp. (p. D55). 

Enlarged brachial, anterior, pedicle, and side views of holotype, USNM 168390, from 

Horseshoe Shale Member, collection 41. 
GEOLOGICAL SU RVEY PRO FESSIONAL PAPER 848- D PLATE 7 

6 

2 10 

7 9 

13 

12 

19 23 20 

4 22 

24 

X2 

5 25 28 29 

X2 X2 _; ~ 

35 

X2 

34 ~ X2 

31 36 41 

39 

42 44 46 48 50 52 

53 

43 47 

45 51 

55 58 

COLEDIUM, PUGNOIDES, AND CLEIOTHYRIDINA 
PLATE 8 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-5,43. Cornposita aff. C. laevis Weller (p. D58) . 

From Horsesho'e Shale Member. 

1-5. Brachial view and enlarged brachial, anterior, pedicle, and side vi·ews of small 

specimen, USNM 168396, from Horseshoe Shale Member, colle-ction 118. 

43. Enlarged ventral view of pedicle valve, USNM 168397, from Horseshoe Shale Member, collection 117. 

6-20. Cornposita poposiensis n. sp. (p. D61). 

From Horseshoe Shale Member. 

6-15. Brachial view and enlarged brachial, anterior, pedicle, and side views of two paratypes, USNM 168408, 168407, collection 38. 

16--20. Brachial view and enlarged brachial, anterior, pedicle, and side views of broad 

depressed variant, paratype, USNM 168404, collection A. 

21-25,36-39. Cornposita sigma n. sp. (p. D59). 

From Hors·eshoe Sale Member. 

21-25. Brachial view and enlarged brachial, anterior, pedicle, and side views of paratype, USNM 168412, collection 47. 

36-39. Enlarged posterior view and pedicle, side, and brachial views of internal mold, 

USNM 168454, collection B. 

26--30. Compos ita sigma n. sp? (p. D60). 

Dorsal view and enlarged dorsal, anterior, ventral and side views of specimen, UM 2652, 

described by Branson and Greger (1918) as Martinia n. sp., from Horseshoe Shale 

Member, co.Jiection 36a. 

31-35,49. Composita st~bquadrata (Hall) (p. D59). 

31-35. Brachial view and enlarged brachial, anterior, pedicle, and side views of immature 

specimen, USNM 168431, from Horse,shoe Shale Member, collection 41. 

49. Enlarged ventral view of pedicle valve, USNM 168430, collection 41. 

40- 42, 44- 48, 50-54. Cornposita sulcata WeHer (p. D62). 

From Horseshoe Shale Member. 

40-42. Pedicle, side, and enlarged posterior views of internal mold, USNM 168455, collection 36e. 

44-48. Brachial view and enlarged pedicle, anterior, side, and brachial views of specimen, USNM 168424, collection A. 

50-54. Enlarged brachial, side, pedicle, and anterior vi•ews and brachial view of another 

specimen, USNM 168423, collection A. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-D PLATE 8 

6 26 31 

11 16 21 

2 Xll.,i 

2 7 

12 

17 22 

27 

3 

4 9 14 19 24 29 34 X 2 

5 10 15 20 25 30 

36 37 39 40 41 42 

43 44 

45 

46 

47 48 

Xll.,i 

53 54 

COMPOSITA 
PLATE 9 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-15, 31-36. Composita poposiensis n. sp. (p. D61). 

From Horseshoe Shale Member. 

1- 5. Brachial view and enlarged brachial, anterior, pedicle, and side views of paratype, USNM 

168403, collection A. 

6- 15. Brachial view and enlarged brachial, anterior, pedicle, and side views of two variant paratypes, USNM 168409, and 168406, collection 38. 

31-36. Brachial view and enlarged bra.chial, posterior, side, anterior, and pedicle views of the 

holotype, USNM 1684·00, collection B. 

16-20. Cmnposita trinuclea (Hall) (p. D62). 

Brachial view and enlarged brachial, anterior, pediele·, and side views of well-preserved specimen, 

USNM 168422, from "Pella Beds," 4% miles south of Pella, Iowa. Included for comparison. 

21-30. Composita sigma n. sp. (p. D59). 

From Horseshoe Shale Member. 

21-25. Brachial view and enlarged brachial, anterior, pedicle, and side views of paratype, YPM 

5154b, collection 44. 

26-30. Brachial view and enlarged brachial, anterior, pedicle, and side views of holotype, USNM 

168411, collection 47. 

37-41. Composita subquadra.ta (Hall) (p. D59). 

37-39. Enlarged brachial, side, and pedicle views of specimen, USNM 168429, from Horseshoe 

Shale Member, collection 41. 

40, 41. Enlarged view and enlarged partial view of poorly preserved pedicle valve interior articulate with hinge plate of brachial valve, USNM 168432, collection 41. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-D PLATE 9 

21 26 

1~ 

2 7 17 22 

3 8 1~ 

4 14 

19 24 

5 10 15 30 

25 

1~ 

31 33 35 

32 

X3 1~ 

41 

37 
PLATE 10 

[Figures natural size unless otherwbe indicated on plate] 

FIGURES 1-15,26-32. Composita ovata Mather (p. D63). 

1- 10. Brachial view an enlarged brachial, anterior, pedicle, and side views of two specimens, 

USNM 168438, 168439, from Horseshoe Shale Member, coUection 3. 

11-15. Brachial view and enlarged brachial, anterior, pedicle, anrd side views of morderately large 

shell, USNM 168434, from Ran chester Limestone Member, collection 14. 

26. Enlarged view of interior of silicified pedicle valve, USNM 168436, collection 14. 

27. Enlarged view of another silicified incomplete shell showing articulation of perdicle and brachial valves, USNM 168437, collection 14. 

28-32. Enlarged brachial view, brachial view, and enlarged pedicle, side, and anterior views of 

immature shell, USNM 168435, coUection 14. 

16-25. Composita elongata Dunbar and Condra (p. D64). 

Brachial view and enlarged brachial, anterior, pedicle, and side views of two specimens, USNM 

168441, 168440, from Hors·eshoe Shale Member, collection 3. 

33-37. Compo•sita subtilita (Hall) (p. D64). 

Brachial view and enlarged anterior, brachial, side, and pedicle views of specimen, USNM 168433, 

collection 136. 
GEOLOGICAL SURVEY 

6 

2 7 

3 

8 

4 9 

33 34 

11 

12 

13 

14 

35 

COMPOSITA 

PROFESSIONAL PAPER 848- D PLATE 10 

16 

17 

18 23 X~ 

19 24 

37 
PLATE 11 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-5. A nth1·acospirijer curvilatemlis CU1"'vilateralis (Easton) (p. D65). 

Brachial, posterior, side, anterior, and pedicle views of topotype, USNM 167735, from Heath Formation, 

Big Snowy Mountains, Mont., USGS collection 16184-PC. 

6-12. Anthracospirije1· curvilateTalis bndus n. subsp. (p. D66). 

6, 12. Ventral and side views of pedicle valve, paratype, USNM 167741, from Horseshoe Shaie Member, 

collection 117. 

7-10. Brachial, side, pedicle, and anterior views of holotype, USNM 167736, from Moffat Trail Limestone Member, collection 79. 

11. Dorsal view of brachial valve, paratype, USNM 167742, collection 117. 

13-18. A nthracospirifer rawlinsensis n. sp. (p. D69). 

From Horsesho,e Shale Member. 

13-15. Ventral, side, and posterior views of large pedicle valve, holotype, USNM 167747, collection 3. 

16. Enlarged dorsal view of part of brachial valve, paratype, USNM 167748, collection 3. 

17, 18. Pedicle and anterior views of slender incomplete specimen, USNM 167753, collection 4. 

19, 20. Anthracospirifer aff. A. occidtms (Sadlick), form A (p. D68). 

Posterior and ventral views of pedicle valve, USNM 167745, from Horseshoe Shale Member, collection 153. 

21-23. Anthracospirifer aff. A. occiduus (Sadlick), form B (p. D69). 

Posterior, ventral, and side views of pedicle valve, USNM 167746, from Ranchester Limestone Member, 

collection 146. 

24-32. A nthracospirije1· occiduus (Sad lick) (p. D67). 

24. Dorsal vie·w of brachial valve, paralectotype, USNM 118717C, from Wells Formation, Websrter 

Range, Idaho, USGS collection 32-PC. 

25. Ve'l'ltral view of pedicle valve, another paralectotype, USNM 118717B, from same collection. 

26-30. Brachial, pedicle, posterior, anterior, and side views of lectotype, USNM 118717 A, same collection. 

31, 32. Latex casts of exterior and interior of brachial and pedicle valve belonging apparently to same 

specimen, hypotype, USNM 167744, from Ranchester Limestone Member, collection 131. 
GEOLOGICAL SURVEY 

2 

1 

11 12 

21 

22 

8 

13 

23 

27 

ANTHRACOSPIRIFER 

PROFESSIONAL PAPER 848-D PLATE II 

..... - .... / ' ' 

9 

14 

' ' ' ' :-.. 

15 
PLATE 12 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-24. Anthracospirije1· welle1-i welleri (Branson and Greger) (p. D72). 

From Horseshoe Shale Member. 

1, 8-12. Enlarged brachial view, brachial, anterior, side, posterior, and pedicle views of 

paralectortype, UM 3532, collection 36b. 

2-7. Brachial, anterior, side, posterior, and pedicle views and enlarged brachial view of 

lectotype, UM 3532, oollection 36b. 

13, 20-24. Enlarged posterior, brachial, anterior, side, posterior, and pedicle views of 

internal mold, hypotype, UW IT-201, illustrated by Burk (1954) as Spirifer opimus 

Hall, collection 22. 

14-19. Brachial, anterior, side, posterior, and pedicle views and enlarged brachial view 

of moderately tran sverse specimen, paralectotype, UM 3532, collection 36b. 

25, 29-33, 37- 42. Anthracospirije1· shawi shawi n. subsp. (p. D70). 

From Horse·shoe Shale Member. 

25. Poorly pres·erved pedicle valve, USNM 167758, collection 137. 

29-33, 37. Brachial, anterior, side, posterior, and pedicle views and enlarged brachial 

view of holotype, UM 2651B, figured by Branson and Greger (1918) as Spirije1· pellaensis Weller, collection 36b. 

38-42. Brachial, anterior, side, pos•terior, and pedicle views of well-preserved paratype, 

USNM 167757, collection F. 

26-28, 34-36, 43-47. Anth?'acospirifm· shawi cxolctus, n. subsp. (p. D71). 

From Horseshoe Shale Member. 

26-28, 43. Enlarged brachial, side, and anterior views and anterior view showing microornament, paratype, UW IT-205, figured by Burk (1954) as Spirifer opimus (Hail), collection 35. Cardinal extremites restored. 

34. Posterior view of silicified specimen, p·aratype, USNM 167755, from collection 38. 

35. Pedicle view of ho.Jotype, UM 2651A, figured by Branson and Greger (1918) as Spirifer pellaensi:; Weller, coiiection 36b. 

36. Posterior view of paratype, UM 3533, also figured by Branson and Greger (1918) as 

Spi1·ijer pe/laensis Weller, collection 36a. 

44-47. Anterior, side, pedicle, and brachial views of silicified specimen lacking parts of 

beak and cardinal extremities, restored, para type, USNM 167754, collection 38. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 848-D PLATE 12 

2 3 4 5 6 

7 

8 

9 

10 

11 12 

13 

14 15 

16 17 18 

26 20 

21 

25 

23 

27 29 

31 

33 32 

28 34 36 37 

38 

39 40 41 42 

ANTHRACOSPIRIFER 
PLATE 13 

[Figures natural size unless otherwise indicated on plate] 

FIGURES 1-7. Anthracospi1·ije1· welleri lincolnensis n. subsp. (p. D7 3). 

1-5. Side, pedicle, posterio·r, brachial, and anterior views of holotype, USNM 167759, from Ranchester Limestone Member, coUection 82. 

6, 7. Ventral and side views of pedicle valve, paratype, USNM 174031, collection 82. 

8-13. ETachythyrina washakiensis n. sp. (p. D74). 

From Horseshoe Shale Member, collection 41. 

8, 9. Side and ventral views of pedicle valve, holotype, USNM 167760. Umbonal area restored. 

10. Incomplete brachial valve, USNM pm·atype 167763. 

11, 12. Posterior and ventral views of pedicle valve, paratype, USNM 167761. 

13. Ventral view of another pedicle valve, paratype, USNM 16772. 

14. Neospirifer praenuntius Easton (p. D75). 

Fragment of umbonal area O·f pedicle valve, showing fasciculation of costae, USNM 166764, from 

Moffat Trail Limestone Member, collection 120. 

15-18, 21, 22. Girtyella cf. G. indianensis ( Girty) (p. D78). 

From Horseshoe Shale Member. 

15-18. Enlarged po·sterior, brachial, pedicle, and side views of partly distorted specimen, UM 

10890, collection 36d. 

21, 22. Enlarged side and dorsal views of brachial valve, UW A11118, collection 28. 

19, 20, 25-29. E umetria sulcata Burk (p. D77). 

From Horsesho·e Shale Member. 

19. Fragment of interior of beak area showing pedicle opening and articulation of both valves, 

USNM 168458, collection 69. 

20. Anterior view of mode1'ately large individual, USNM 168457, collection 38. 

25-29. Enlarged anterior view, brachial view, and enlarged brachial, side, and pedicle views of 

holotype, UW IT-231, collection 35. 

23, 24,30-46. Retic,ulariina browni (Branson and Greger) (p. D75). 

From Horseshoe Shale Member. 

23. Enlarged dorsal view of brachial valve, showing details of sp·ine arrangement, hypotype, 

USNM 168445, collection 69. 

24. Enlarged ventral view of pedicle valve, showing similar detals, hypotype, USNM 168444, collection 69. 

30, 38-41. Pedicle view and enlarged pedicle, posterior, brachial, and anterior views of hypotype, USNM 168442, collection 27. 

31-35, 42. Brachial, posterior, side, anterior, and pedicle views and enlarged pedicle view, showing minute spines and punctae, lectotype, UM 2656, bearing attached Cornulitella figured by 

Branson and Greger as Ortonia cf. 0. blatchleyi Beede, collection 36b. 

36, 37, 43- 45. Posterior, brachial, side, anterior, anrl. pedicle views of paralectotype, UM 2650, 

collection 36c. 

46. Enlargement of anterior part of pedicle valve, showing arrangement of fine spines that protrude through thin limonitic coating, hypotype USNM 168443, collection 27. 

47, 48. Torynifer setiger (Hall)? (p. D65). 

Dorsal view and enlarged dorsal view of latex cast of brachial valve, USNM 168456, from Horseshoe Shale Member, collection 45. 
GEOLOGICA L SURVEY PROFESSIONAL PAPER 848-D PLATE 13 

3 5 

1 2 4 6 

l li 

15 

16 17 18 

8 10 

19 .... ~ .• 

20 

l!i 

24 26 27 28 

30 31 32 33 34 35 36 

37 

46 48 

ANTHRACOSPIRIFER, BRACHYTHYRINA, NEOSPIRIFER, GIRTYELLA, 

EUMETRIA,RETICULARIINA, AND TORYNIFER