An Appraisal of the 

Great Basin Middle 

Cambrian Trilobites 

Described Before 1900

By ALLISON R. PALMER

A SHORTER CONTRIBUTION TO GENERAL GEOLOGY

GEOLOGICAL SURVEY PROFESSIONAL PAPER 264-D

Of the 2ty species described prior to I(?OO, 

2/ are redescribed and 2C} refigured, and a 

new name is proposed for I species

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1954
UNITED STATES DEPARTMENT OF THE INTERIOR 

Douglas McKay, Secretary

GEOLOGICAL SURVEY 

W. E. Wrather, Director

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

Washington 25, D. C. - Price $1 (paper cover)
CONTENTS

Abstract..__________________________________

Introduction ________________________________

Original and present taxonomic names of species. 

Stratigraphic distribution of species ____________

Collection localities._________________________

Systematic descriptions.______________________

Literature cited____________________________

Index __-_-__-__---_--______________________

Page 

55 

55 

57

57

58

59

82

85

ILLUSTRATIONS

[Plates 13-17 follow page 86] 

PLATE 13. Agnostidae and Dolichometopidae

14. Dorypygidae

15. Oryctocephalidae, Dorypygidae, Zacanthoididae, and Ptychoparioidea

16. Ptychoparioidea

17. Ptychoparioidea 

FIGUBE 3. Index map showing collecting localities____________________________ . Page 56 

in

A SHORTER CONTRIBUTION TO GENERAL GEOLOGY

AN APPRAISAL OF THE GREAT BASIN MIDDLE CAMBRIAN TRILOBITES

DESCRIBED BEFORE 1900

By ALLISON R. PALMER

ABSTRACT

All 29 species of Middle Cambrian trilobites that were described from the Great Basin of Western United States prior to 

1900 are refigured and 27 redescribed. Complete information 

is presented concerning the stratigraphic occurrences of the 

species in terms of present knowledge of the Cambrian stratigraphy of the Great Basin, the original and present taxonomic 

designations of the species, and the localities from which the 

species were obtained. A new name, Modocia nevadensis, is 

proposed to replace Modocia oweni (Walcott) not Modocia oweni 

(Meek and Hay den).

INTRODUCTION

This paper has been prepared as a reference for paleontologists and stratigraphers dealing with the Middle 

Cambrian rocks and their included fossils in the Great 

Basin of Western United States.

Cambrian trilobites from the Great Basin were first 

collected by field parties of the U. S. Geographical and 

Geological Surveys West of the 100th meridian and the 

U. S. Geological Exploration of the 40th Parallel in the 

late 1860's and early 1870's. A total of 11 species of 

Middle Cambrian age were described by Meek (1870, 

1873), White (1874, 1877), and HaU and Whitfield 

(1877) from Survey collections from the House, Oquirrh, 

and Wasatch Kanges of Utah (fig. 3). The only other 

published records before 1900 of Middle Cambrian 

trilobites from the Great Basin are by Walcott (1884, 

1886) who collected and described a total of 18 species 

mostly from the Eureka and Pioche mining districts 

and the Highland Kange in Nevada.

Although many of these Great Basin species described 

in the early reports have been discussed, illustrated, or 

mentioned since 1900 and some additional material 

has been described, no comprehensive reexamination 

of the trilobites from the early collections has ever 

been presented. The original engraved illustrations 

and most of the subsequent photographic illustrations 

of the species are inadequate according to present 

paleontologic standards. Furthermore, references to

the species and changes in their generic assignments 

are scattered through many publications by both 

American and foreign paleontologists. An understanding of those species is a necessary prerequisite to 

any study of Middle Cambrian trilobites from the 

Great Basin. However, in most instances, such an 

understanding cannot be gained by reading published 

descriptions and examining published illustrations of 

the species.

All of the species reported from Middle Cambrian 

rocks of the Great Basin before 1900 are either described or discussed, or both, hi this publication. Unless otherwise stated, the specimens figured in the 

original illustrations are shown on plates 13-17 by 

stereophotographs. The history of each species name 

is given in the synonymy or discussion of the species. 

Original descriptions are quoted where there is little 

or no new descriptive information. The original and 

the present generic assignments of the species are listed 

on page 57; the stratigraphic and geographic occurrences of the type specimens of each species are listed on 

pages 57 and 58; and detailed locality information is given 

on page 58. Unless otherwise stated only the formation and locality from which the type or figured material 

came is listed.

The assignments of trilobites to particular formations 

in the Eureka district result from the study of material 

collected by the writer or Josiah Bridge since the 

formational sequence was redescribed by Wheeler and 

Lemmon (1939). The sequence was first described, 

in what is now considered to be correct stratigraphic 

order, by Hague (1883), and most of the present formational names were proposed by him or by Walcott 

(1908). Kesser believed that the Dunderberg shale, 

and Secret Canyon shale were partial equivalents. In 

accordance with this interpretation, Resser assigned! 

(1935, 1936, 1937, and in Walcott, 1924, 1925) the 

Dunderberg faunas to the Secret Canyon shale and 

the Secret Canyon faunas to the Eldorado limestone.

55
56 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

116° 115

FIGURE 3.—Map showing areas in the Great Basin trom which Middle Cambrian trilobites described before 1900 were obtained.

Wheeler and Lemmon (1939) reassigned most of the 

described trilobites from the Eureka district to the 

formations from which they were originally collected. 

However, their Geddes limestone and the Hamburg 

limestone, which they state to be sparingly fossiliferous 

and to lack diagnostic fossils, contain distinctive faunas

assignable to the Bathyuriscus-Elraihina zone (Rasetti, 

1951) and an unnamed latest Middle Cambrian zone 

respectively.

Stratigraphic assignments for the fossils from areas 

outside of the Eureka District are based principally on 

the work of Deiss (1938).
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 57

ORIGINAL AND PRESENT TAXONOMIC NAMES OF SPECIES

The taxonomic designation used in this paper for each of the 29 species described from the Middle Cambrian 

rocks of the Great Basin prior to 1900 is given below.

Original name Present name

Agnostus interstrictus White__________________________________________ Peronopsis interstrictus (White).

Agnostus richmondensis Walcott— ___________________________________ Ptychagnostus richmondensis (Walcott).

Agnostus seclusus Walcott___________________________________________ Kormagnostus seclusus (Walcott).

Asaphiscus wheeleri Meek__-__-__________ — _________________________ Asaphiscus wheeleri Meek.

Bathyuriscus howelli Walcott ________________________________________ Athabaskia howelli (Walcott).

Conocephalites subcoronatus Hall and Whitfield_______________________ Alokistocare subcoronatum (Hall and Whitfield).

Conocoryphe (Conocephalites) kingii Meek_______________________._____ Elrathia kingii (Meek).

Crepicephalus? (Loganellus) quadrans Hall and Whitfied________________ Ehmaniella quadrans (Hall and Whitfield).

Crepicephalus augusta Walcott.-_____________________________________ Kochaspis augusta (Walcott).

Crepicephalus liliana Walcott._______________________________________ Kochaspis liliana (Walcott).

Dicellocephalus expansus Walcott___________________________________ Olenoides expansus (Walcott).

Dicellocephalusf quadriceps Walcott__________________________________ Kootenia eurekensis (Resser).

Dikellocephalusf gothicus Hall and Whitfield_________________________ Kootenia quadriceps (Hall and Whitfield).

Dikellocephalus quadriceps Hall and Whitfield________________________ Kootenia quadriceps (Hall and Whitfield).

Dikellocephalus wahsatchensis Hall and Whitfield_______________________ Olenoides wahsatchensis (Hall and Whitfield).

parabola Hall and Whitfield_________________________________ Glossopleura producta (Hall and Whitfield).

jia problematica Walcott.._______________________________________ Holteria problematica (Walcott).

producta Hall and Whitfield_________________________________ Glossopleura producta (Hall and Whitfield).

nnosa Walcott___-___--__-________________________________ Zacanthoides spinosus (Walcott).

Olenoides typicalis Walcott-_________________________________________ Zacanthoides typicalis (Walcbtt).

Oryctocephalus primus Walcott_____________________________________ Oryctocephalus primus Walcott.

Paradoxides nevadensis Meek________________________________________ Olenoides nevadensis (Meek).

Ptychoparia housensis Walcott_______________________________________ Bolaspidella housensis (Walcott).

Ptychoparia laeviceps Walcott________________________________________ Asaphiscus laeviceps (Walcott).

Ptychoparia? linnarssoni Walcott___________________________________ Eldoradia linnarssoni (Walcott).

Ptychoparia occidentalis Walcott _____________________________________ Elrathia occidentalis (Walcott).

Ptychoparia oweni Walcott-_________________________________________ Modocia nevadensis Palmer, n. sp.

Ptychoparia piochensis Walcott-_____________________________________ Alokistocare piochensis (Walcott).

Ptychoparia? prospectensis Walcott ___________________________________ Eldoradia prospectensis (Walcott).

STRATIGRAPHIC DISTRIBUTION OF SPECIES

In the following table is given the stratigraphic distribution of 26 species of Middle Cambrian trilobites 

described froir the Great Basin prior to 1900.

Stratigraphic distribution of trilobites

Localit;

Wasatch Range, Utah.

Formation

Ute limestone.

Spence shale member of the Ute 

limestone.

Fauna

Alokistocare subcoronatum (Hall and Whitfield). 

Kootenia quadriceps (Hall and Whitfield).

Ehmaniella quadrans (Hall and Whitfield). 

Olenoides wahsatchensis (Hall and Whitfield).

Oquirrh Range, Utah..____ Ophir shale (?). Glossopleura producta (Hall and Whitfield).

House Range, Utah. Wheeler formation. Asaphiscus wheeleri Meek. 

Bolaspidella housensis (Walcott). 

Elrathia kingii (Meek). 

Olenoides nevadensis (Meek). 

Peronopsis interstrictus (White).

Pioche district, Nev. Chisholm shale. Alokistocare piochensis (Walcott). 

Athabaskia howelli (Walcott). 

Zacanthoides typicalis (Walcott).

Pioche shale. Kochaspis augusta (Walcott). 

Kochaspis liliana (Walcott). 

Oryctocephalus primus (Walcott).
58 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Stratigraphic distribution of trilobites—Continued

Locality

Eureka district, Nev ______

Formation

Hamburg limestone (Lower) ________

Secret Canyon shale __ _ _ __ __ _

Geddes limestone of Wheeler and 

Lemmon (1939).

Fauna

Asaphiscus laeviceps (Walcott).

Holteria problematica (Walcott). 

Kormagnostus seclusus (Walcott). 

Modocia nevadensis Palmer, n. sp.

Eldoradia linnarssoni (Walcott).

Eldoradia prospectensis (Walcott).

Elrathia occidentalis (Walcott). 

Olenoides expansus (Walcott). 

Ptychagnostus richmondensis (Walcott). 

Zacanthoides spinosus (Walcott).

COLLECTION LOCALITIES

The following list gives complete data for those 

localities referred to by number in the plate descriptions. 

Numbers in Systematic descriptions followed by (OS) 

refer to old series numbers that were assigned to 

collections under a numbering system established by 

Walcott and used by Walcott, Resser, Ulrich and others

until 1940. Numbers followed by (CO) refer to 

Cambrian and Ordovician collections numbered under 

a system established by Josiah Bridge and used since 

1940.

The present formational assignment and, wherever 

known, the name or names of the original collectors 

are presented for each locality.

U. S. Geological Survey Collections

Locality 

No.

3c (OS)

20x (OS)

30 (OS)

31 (OS)

31a (OS)

52a (OS)

55a (OS)

55b (OS)

Stratigraphic assignment, collector, year of collection, trilobites collected

Shales about 75 feet above the quartzitic sandstones of the Cambrian at 

Ophir, Oquirrh Range, Tooele County, Utah (Ophir formation?). 

Collector not known. *

Olossopleura producta (Hall and Whitfleld).

In Wasatch Range near top of gulch, about 2 miles north of Brigham City, 

Utah (Spence shale member of the Ute limestone). C. E. Resser, Asa 

A. L. Mathew, E. R. Pohl, Sept. 12, 1926.

Ehmaniella quadrans (Hall and Whitfleld).

Limestone 8 miles north of Bennetts Spring, on the west slope of the 

Highland Range, Lincoln County, Nev. (Pioche shale). C. D. Walcott, 1885.

Kochaspis liliana (Walcott). 

Kochaspis nevadensis Resser.

Shales at the Chisholm Mine, southwest slope of Ely Mountains, 3 miles 

northwest of Pioche, Lincoln County, Nev. (Chisolm shale). C. D. 

Walcott, 1885.

Alokistocare piochensis (Walcott). 

Athabaskia howelli (Walcott). 

Zacanthoides typicalis (Walcott).

Limestone and interbedded siliceous shales of the Pioche formation just 

above the quartzite on the east side of the anticline near Pioche, Lincoln 

County, Nev. (Pioche shale). C. D. Walcott, 1885. 

Kochaspis augusta (Walcott). 

Kochaspis liliana (Walcott). 

Oryctocephalus primus Walcott.

500 to 600 feet down northeast slope of Prospect Mountain, Eureka district, Eureka County, Nev. (Secret Canyon shale). C. D. Waleott, 

1880.

Eldoradia prospectensis (Walcott).

Just beneath Secret Canyon shale on east side of Prospect Mountain, 

Eureka district, Eureka County, Nev. (Geddes limestone of Wheeler 

and Lemmon). C. D. Walcott, 1880.

Elrathia occidentalis (Walcott).

Black limestone on west side of Secret Canyon, Eureka district, Eureka 

County, Nev. (Geddes limestone of Wheeler and Lemmon). C. D. 

Walcott, 1880. 

Kootenia eurekensis Resser. 

Olenoides expansus (Walcott).

Locality

No.

58 (OS)

329 (OS)

329e (OS)

806 (CO)

600 (CO)

901 (CO)

965 (CO)

Stratigraphic assignment, collector, year of collection, trilobites collected

Shaly limestones on east side of New York and Secret Canyons, Eureka 

district, Eureka County, Nev. (Hamburg limestone). C. D. Walcott, 

1880.

Asaphiscus laeviceps (Walcott).

Hotteria problematica (Walcott).

Kormagnostus seclusus (Walcott).

Modocia nevadensis Palmer, n. sp.

Eldoradia linnarssoni (Walcott). 1

Green shales in a canyon about 7 miles north of Brigham, near the village 

of "Calls Fort," Boxelder County, Utah. (Spence shale member of 

the Ute limestone). Collector not known. 

Ehmaniella quadrans (Hall and Whitfleld). 

Olenoides wahsatchensis (Hall and Whitfleld).

Shales in East Canyon above Ophir, Oquirrh Range, Tooele County, 

Utah (Ophir formation?). Collector not known. 

Olossopleura producta (Hall and Whitfleld).

Basal Hamburg limestone. Crest of Hamburg Ridge, about 15 feet south 

of propsect pit, 2,350 feet N. 10° E. of the Eureka tunnel, elevation 8,005 

feet, Eureka district, Eureka County, Nev. J. Bridge, Aug. 30, 1939. 

Kormagnostus seclusus (Walcott).

Piece of "Blue flaggy" (Geddes of Wheeler and Lemmon) float at road 

junction 1,400 feet W. of N. from pass at head of Secret Canyon (Between Secret and Windfall canyons), Eureka district, Eureka County, 

Nev. J. Shelton, July 18, 1940. 

Zacanthoides spinosus (Walcott).

Outcrop of "Blue flaggy" (Geddes of Wheeler and Lemmon) limestone 

in beds about 1 inch thick on nose of small ridge 2,250 feet S. 41° 30' W. 

from BM 8077 on pass between Windfall and New York Canyons. 

Eureka district, Eureka, Nev. J. Shelton, July 29, 1940. 

Ptychagnostus richmondensis (Walcott).

Geddes limestone (of Wheeler and Lemmon) on side of Prospect Mountain, 20 feet below large outcrop of gray limestone in middle of slope at 

west end of Windfall Canyon. Eureka district, Eureka, Nev. A. R. 

Palmer, Aug. 1951. 

Ptychagnostus richmondensis (Waleott).

This species is from a horizon different than that of the other four listed.
APPRAISAL OP GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 59

SYSTEMATIC DESCRIPTIONS

The descriptive terminology used here is the same 

as that used by the writer (Palmer, in press) in an 

earlier publication. Measurements of figured specimens are given to the nearest one-half millimeter. All 

of the illustrations on the plates are stereophotographs.

Family AGNOSTIDAE McCoy, 1849

The writer has followed the suprageneric classification of Westergard (1946) wherever possible within 

this family.

Subfamily PERONOPSINAE Westergard, 1936 

Genus KORMAGNOSTUS Resser, 1938

Kormagnostus Resser, 1938, Geol. Soc. America Special Paper 

15, p. 49.

Lochman, 1940, Jour. Paleontology, v. 14, no. 1, p. 24. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 600. 

Palmer, 1954, in press, Jour. Paleontology.

Genotype.—Kormagnostus simplex Resser, 1938 

(1938a, p. 49).

Diagnosis.—Cephalon with anterior lobe of glabella 

completely or nearly completely effaced; basal glabellar 

lobes present. Pygidium with broad, elongate, welldefined axial lobe that is bluntly rounded posteriorly 

and extends to or nearly to the marginal furrow. 

Posterolateral marginal spines usually present.

Discussion.—This genus may have been derived from 

Hypagnostus. The principal distinguishing difference 

is in the pygidium. Most pygidia of species of Hypagnostus, as illustrated by Westergard (1946, pis. 4-6) 

lack marginal pygidial spines and have a posteriorly 

pointed and sometimes longitudinally shortened axial 

lobe. These differences are important from a stratigraphic viewpoint because Hypagnostus is known only 

from rocks of Middle Cambrian age, and Kormagnostus 

is almost exclusively Late Cambrian in age. The only 

species of Hypagnostus that has marginal spines on the 

pygidium comes from the Lejopyge laevigata zone at the 

top of the Middle Cambrian in Sweden.

Kormagnostus seclusus (Walcott) 

Plate 13, figures 1-3

Agnostus seclusus Walcott, 1884, U. S. Geol. Survey Mon. 8, p. 

25, pi. 9, fig. 14

Description.—Cephalon slightly wider than long, 

somewhat expanded forward, strongly rounded at the 

anterolateral corners, gently rounded across the front, 

and moderately arched transversely and longitudinally. 

Glabella about one-half the length and one-third the 

width of the cephalon; tapered slightly forward and 

squarely truncate anteriorly. Anterior lobe of the

296334—54——2

glabella not visible on the type specimen but suggested, on a specimen recently collected, by a low, 

undefined swelling. Posterior lobe highest near the 

posterior margin; a pair of short furrows notch the 

sides of the lobe about one-third of its length from the 

anterior end, and a low median node may be present 

just posterior to a line connecting these furrows. 

Occipital furrow shallow, and occipital ring narrow. 

Basal lobes subtriangular in outline and undivided. 

Cheeks undivided and slope gently away from the 

glabella toward the anterior margin and steeply away 

toward the posterolateral margin. Border narrowest 

at the posterolateral corners of the cephalon and expands slightly forward. Surface of the cephalon 

smooth.

Pygidium slightly wider than long, nearly parallelsided, broadly rounded posteriorly, and moderately 

arched transversely and longitudinally. Axial lobe 

nearly parallel-sided, about four-fifths the length and 

slightly less than one-half the width of the pygidium, 

strongly rounded posteriorly and undivided by furrows. 

It reaches nearly to the marginal furrow. Small, 

distinct median node situated on the axial lobe about 

one-third the length of the lobe from the anterior end 

of the pygidium. Pleural platforms narrow and downsloping from the axial lobe to the border. Marginal 

furrow broad and shallow. Border moderately wide 

and bears a pair of short, sharp lateral spines about 

opposite the posterior end of the axial lobe; surface 

smooth.

Discussion.—K. seclusus (Walcott) was described 

from the cranidium only. The type specimen is associated with Modocia nevadensis Palmer, n. sp., Asaphiscus laeviceps (Walcott), and Holteria problematica 

(Walcott) in USGS collection 58 (OS) from the Eureka 

district. A nearly identical cephalon and several 

associated pygidia of K. seclusus (Walcott) occur with , 

these species in USGS collection 806 (CO) from the 

same area. The pygidia are considered to belong to 

the species and are described above.

The cephalon of this species is similar to that oi K. 

simplex Resser from the lower Upper Cambrian but 

differs principally in having the anterior margin strongly 

rounded at the anterolateral corners and gently rounded 

across the front instead of evenly rounded. The 

pygidium is distinguished by having a nearly parallelsided axial lobe.

Kobayashi (1939, p. 171) referred A. seclusus Walcott 

with doubt to Geragnostus ( Geragnostella). He was 

apparently misled by the drawing in Walcott's monograph. Examination of the type shows that A. seclusus 

Walcott lacks the distinct anterior glabellar lobe characteristic of Geragnostus and Geragnostella.
60 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Occurrence.—Rare, Middle Cambrian, basal portion 

of the Hamburg limestone.

Figured specimens.—Holotype, cephalon, USNM 

24586, length, 3 millimeters; cephalon, USNM 123353a, 

length, 2.5 millimeters; pygidium, USNM 123353b, 

length, 2.5 millimeters.

Genus PERONOPSIS Hawle and Corda, 1847

Peronopsis Hawle and Corda, 1847, Prodrom einer Monographie

der bohmischen Trilobiten, p. 115. 

Kobayashi, 1939, Tokyo Imp. Univ., Fac. Sci., Jour., sec. 2,

v. 5, pi. 5, p. 115. 

Westerg^ard, 1946, Sveriges geol. undersokning, ser. C, no.

477, Arsbok 40, no. 1, p. 36.

Mesophenicus Hawle and Corda, 1847, op. cit., p. 46. 

Diplorrhina Hawle and Corda, 1847, op. cit., p. 46.

Whitehouse, 1936, Queensland Mus. Mem., v. 11, p. 88. 

Mesagnostus Jaekel, 1909, Deutsche Geol. Gesell. Zeitschr.,

Band 61, p. 398.

Quadragnostus Howell, 1935, Jour. Paleontology, v. 9, no. 3, p. 

____219._____

Genotype.—Battus integer Beyrich, 1845 (p. 44).

Diagnosis.—Cephalon with glabella bilobed, tapered 

forward; no median longitudinal preglabellar furrow; 

basal glabellar lobes simple. Pygidium with axial lobe 

usually bluntly pointed posteriorly; length variable; 

transverse axial furrows shallow or absent; margin 

with or without a pair of posterolateral spines.

Discussion.—This genus is abundant and widespread 

in the Middle Cambrian rocks of the Great Basin. 

The bilobed glabella and the lack of a preglabellar 

median furrow on the cephalon and the posteriorly 

pointed, unfurrowed axial lobe on the pygidium distinguish it from other agnostids in the area,.

Mesophenicus, Diplorrhina, Mesagnostus, and Quadragnostus were considered to be synonyms of Peronopsis by Kobayashi (1939, p. 115). There is no reason to 

question his conclusion.

Peronopsis interstrictus (White) 

Plate 13, figure 6

Agnostus interstrictus White, 1874, U. S. Geog. and Geol. Surveys

W. 100th Mer. Rept., p. 7. 

White, 1877, U. S. Geog. and Geol. Surveys. W. 100th Mer.

Kept., v. 4, p. 38, pi. 2, figs. 5a, b. 

Walcott, 1886, U. S. Geol. Survey Bull. 30, p. 149, pi. 16,

figs. 6, 6a. 

Shinier and Shrock, 1944, Index Fossils of North America,

p. 600, pi. 251, figs. 16-17.

Description.—The full description of this species 

given by White (1877, p. 38) cannot be improved upon.

Head and pygidium of almost exactly equal size and general 

shape and otherwise closely resembling each other.

Head a trifle broader than long, regularly rounded in front; 

sides at the postero-lateral regions subparallel; postero-lateral 

angles truncated; the whole exterior margin, including the truncated portions just named, provided with a narrow, raised rim 

the elevation of which forms a linear depression, or groove, 

between it and those portions of the head which it incloses; 

space between this marginal depression and the glabella a little 

wider posteriorly than it is in front, convex throughout, and its 

surface apparently smooth. Glabella conical, widest posteriorly, 

moderately convex, sides nearly straight, well defined by the 

dorsal furrows, abruptly rounded in front; a minute tubercle 

situated on the median line near the posterior end, and a shallow 

groove or furrow extending across near the front end, defining 

a frontal lobe of moderate size.

Thorax narrower than the head and pygidium, giving the body 

the appearance of being constricted at the middle; axial lobe 

broad, consisting of two segments, both of which are tumid at 

the ends adjoining the dorsal furrows; lateral lobes very narrow; 

pleurae almost as wide as long; each pleura tumid and rounded 

at its exterior end.

Pygidium having an outline like that of the head, and is also 

provided with a similar elevated marginal rim and linear depression within it; axial lobe a little longer than the glabella, and 

consequently that lobe reaches a little nearer the posterior margin 

of the pygidium than the glabella does to the anterior margin 

of the head, moderately convex in elevation and also in each 

lateral outline; a minute tubercle is situated on the median line 

near the anterior end, corresponding in size and relative position 

with the one on the glabella before mentioned; space between 

the dorsal furrows and the margin convex, its surface apparently 

smooth; upon the outer edge of the border of the pygidium, at 

each side and a little nearer to the axial extremity than to the 

antero-lateral angles, there is a minute protuberance, suggestive 

of an incipient spine. Besides the slight differences between the 

head and pygidium, already referred to, the pygidium differs 

also in having a faint appearance of segmentation of its axis 

and in a slight folding backward of the marginal rim at the 

antero-lateral angles.

Length of body, 8mm ; width of head and also of the pygidium, 

5mm ; width of thorax, 4mm .

Discussion.—The types of this species are slightly 

crushed but not badly distorted. The relatively large 

subtriangular anterior lobe of the glabella distinguishes 

the species from all other species of Peronopsis.

Kobayashi (1939, p. 120) placed Agnostus interstrictus 

White in Armagnostus Howell, which he considered a 

subgenus of Peronopsis. Armagnostus is now stated to 

be a synonym of Homagnostus Howell (Lochman and 

Duncan, 1944, p. 139). A. interstrictus White has all 

of the characteristics of Peronopsis and is retained in 

that genus. It lacks the preglabellar median furrow 

considered to be diagnostic of Homagnostus.

Occurrence.—Moderately common, Middle Cambrian, 

Wheeler formation, House Range, Utah, associated with 

Elrathia kingii (Meek), Asaphiscus wheeleri Meek, and 

Bolaspidella sp.

Figured specimen.—Holotype, complete carapace, 

USNM 15405, length, 8 millimeters.

Subfamily AGNOSTINAE Jaekel, 1909 

Genus PTYCHAGNOSTUS Jaekel, 1909

Ptychagnostus Jaekel, 1909, Deutsche geol. Gesell. Zeitschr., 

Band 61, p. 401.
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 61

Kobayashi, 1939, Tokyo Imp. Univ., Fac. Sci., Jour., sec. 2,

v. 5, pt. 5, p. 152. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 600. 

Westergard, 1946, Sveriges geol. undersokning, ser. c, no.

477, Arsbok 40, no. 1, p. 67.

Genotype.—Agnostus punctuosus Angelin, 1851 (p. 8).

Diagnosis.—Cephalon with glabella bilobed, tapered 

forward; median longitudinal preglabellar furrow present; basal glabellar lobes simple or divided. Pygidium 

with axial lobe usually bluntly pointed posteriorly; 

anterior third separated from posterior portion and 

subequally divided by distinct transverse furrows; 

margin usually without posterolateral spines.

Ptychagnostus richmondensis (Walcott) 

Plate 13, figures 4, 5

Agnostus richmondensis Walcott, 1884, U. S. Geol. Survey

Mon. 8, p. 24, pi. 9, fig. 10. 

Agnostus bidens Walcott [not Meek], 1884, idem, p. 26, pi. 9,

figs. 13, 13a.

Diagnosis.—Cephalon with cheeks scrobiculate; basal 

glabellar lobes divided; long posterolaterally curved 

postcephalic spines present. Pygidium with axial lobe 

bluntly pointed posteriorly, reaching nearly to border; 

width about equal to that of pleural lobes; posterolateral 

marginal spines absent.

Description.—The cephalon is about as wide as long, 

slightly expanded forward, strongly rounded anteriorly 

and moderately arched transversely and longitudinally. 

The glabella is about three-fourths the length and onethird the width of the cephalon, tapered evenly forward, 

and bluntly pointed anteriorly. The anterior lobe is 

subtriangular in outline, only slightly elevated above 

the cheeks, about one-third the length of the glabella, 

and separated from the posterior lobe by a distinct 

transverse furrow. The posterior lobe rises to a high 

point near the posterior margin. A pair of short 

furrows notch the sides of the lobe about one-third of 

its length from the anterior end. A low median node is 

situated between the anterior tips of the basal lobes. 

The occipital furrow is distinct, and the occipital ring 

is narrow, with a small median node. The basal lobes 

are elongate subtriangular in outline, with a distinct 

shallow transverse furrow about one-third the length 

of each lobe from its anterior end. A median longitudinal furrow extends from the front of the glabella to 

the anterior border. The cheeks slope gently away 

from the glabella towards the anterior margin and 

steeply away towards the posterolateral margin. Furrows of varying lengths frequently alternating long and 

short extend most of the distance from the border 

across the cheeks towards the glabella. The pattern of 

the furrows varies from specimen to specimen and is often

different on the right and left cheeks of the same specimen. The border is narrow, distinct, and of even width. 

Long slender postcephalic spines extend backward from 

the posterior margin of well-preserved specimens. The 

surface of the cephalon is smooth.

The pygidium is slightly wider than long, nearly 

parallel-sided, broadly rounded posteriorly, and moderately arched transversely and longitudinally. The 

axial lobe is about four-fifths the length and two-fifths 

the width of the pygidium and divided by 2 strong 

transverse furrqws into 3 segments. The anterior 

segment is short, and the dorsal furrow along the lateral 

margins diverges forward. The second segment is 

longest on the axial line and is bounded distally by 

nearly parallel portions of the dorsal furrow. A distinct, slightly elongate median node is situated at the 

posterior margin of this segment. The posterior segment, which is nearly twice the combined length of the 

first 2 segments, tapers to a blunt point that is connected to the margin by a longitudinal furrow on many 

specimens. The pleural platforms are downsloping 

from the axis and do not bear radial furrows as do the 

corresponding portions of the cephalon. The border 

is distinct, slightly wider than that of the cephalon, and 

without margiaal spines. A pair of short, blunt, anteriorly directed spines is present on the anterior 

margin of the pygidium. The surface of the pygidium 

is smooth.

Discussion.—This species was described from the 

cranidium only. Recent collections contain many 

cranidia and associated pygidia that unmistakably 

belong to it. Walcott's original specimen could not be 

located in the U. S. National Museum collections, but 

there is no doubt from his description and figure that 

the specimens described here are conspecific with it.

Vogdes (1892, p. 389) considered this species to be a 

synonym of A. americanus Billings. Kobayashi (1939, 

p. 165) rightly questioned this assignment and suggested 

that A. richmondensis Walcott might belong to Lotagnostus Whitehouse; however, it lacks the prominent 

transverse trilobation of the axial lobe of the pygidium 

of that genus. The preglabellar median furrow on the 

cephalon and the posteriorly pointed axial lobe of the 

pygidium suggest that this species belongs to Ptychagnostus Jaekel.

Ptychagnostus richmondensis (Walcott) is nearly 

identical to P. atavus (Tullberg), originally described 

from the zone of that name in the Paradoxides proxissimus stage of the Middle Cambrian of Sweden and 

subsequently reported by Whitehouse (1936, p. 85) and 

confirmed by Westergard (1946, p. 76) from the 

Dinesus stage of the Middle Cambrian of Australia. 

The principal difference exhibited by P. richmondensis 

(Walcott) is the presence of long postcephalic spines.
62 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

These have not been reported for P. atavus (Tullberg). 

In all other respects the analysis given by Whitehouse 

for P: atavus (Tullberg) fits the Nevada specimens 

perfectly.

The specimens illustrated by Walcott as Agnostus 

Widens Meek are not even congeneric with Meek's 

species; and, in addition, the illustrated "cephalon" is 

a pygidium as suspected by Kobayashi (1939, p. 161). 

Kobayashi, however, misinterpreted the drawings of 

the Eureka specimens and erroneously assigned the 

pygidium (Walcott, 1884, fig. 13a) to Agnostus and the 

"cephalon" (Walcott, 1884, fig. 13) to Geragnostus. 

Both specimens are pygidia of P. richmondensis 

(Walcott).

The type specimens of A. bidens Meek belong to the 

genus Peronopsis.

Occurrence.—Moderately common, Middle Cambrian, 

Geddes limestone of Wheeler and Lemmon (1939) 

Eureka district, Nev.

Figured specimens.—Cephalon, USNM 123354, length 

(not including spines), 3 millimeters; pygidium, USNM 

123355, length 3 millimeters.

Superfamily COEYNEXOCHOIDEA Kobayashi, 1935

Rasetti (1948, 1951) has discussed the suprageneric 

classification within this superfamily in some detail. 

The writer has used that classification wherever 

possible.

Family DORYPIGIDAE Kobayashi, 1935 

Genus OLENOIDES Meek, 1877

Olenoides Meek, 1877, U. S. Geol. Expl. 40th Par. Rept. v. 4,

p. 25. 

Kobayashi, 1935, Tokyo Imp. Univ., Fac. Sci., Jour.,

sec. 2, v. 4, pt. 2, p. 152 [complete synonymy]. 

Neolenus Matthew, 1899, Royal Soc. Canada Proc. and Trans., 

2d ser. v. 5, sec. 4, p. 52 [see Kobayashi, 1935, idem 

for references to that date]. 

Lake, 1938, Paleontographical Soc., v. 91, p. 260.

Genotype.—Paradoxides? nevadensis Meek, 1870 

(p. 62).

Diagnosis.—Cephalon subsemicircular in outline; 

posterior margin nearly straight; genal spines originating from posterolateral corners. Cranidium sub trapezoidal in outline. Glabella parallel sided or slightly 

expanded forward, prominently elevated above cheeks, 

reaching to border, smooth or faintly furrowed, well 

defined by dorsal furrow. Occipital furrow distinct. 

Occipital ring usually bears median spine. Fixed 

cheeks narrow, less than one half width of glabella. 

Ocular ridges distinct, strongly backswept from anterolateral margin of glabella. Distinct pits are present 

in dorsal furrow at junction with ocular ridge. Palpebral lobes small, situated opposite middle third of

glabella. Posterior limbs long, wide; marginal furrow 

distinct.

Thorax consists of about seven segments. Axial 

portion of segments often with median node or spine. 

Pleural portions with distinct, posterolaterally directed 

furrow originating near inner anterior corner of lobe. 

Marginal spines sharp. Axial lobe gently to moderately tapered posteriorly.

Pygidium subsemicircular in outline. Axial lobe well 

defined by dorsal furrow, tapered posteriorly, reaching 

to or nearly to the inner margin of the border. Pleural 

lobes with distinct interpleural grooves and diagonal 

pleural furrows. Pleural furrows usually deepest. 

Margin with four or more pairs of posteriorly or posterolaterally directed, nearly horizontal spines.

Discussion.—Walcott (1925, p. 92) pointed out that 

the cranidia of Neolenus (Olenoides), Kootenia, and 

Holteria—the writer would also add Dorypyge—in the 

absence of the distinctive pygidia, could well be retained in one genus. The generic and specific characteristics in this group are almost entirely in the pygidia. 

Few cranidia show even distinctive specific characteristics. Many of the "species" of these genera described from cranidia alone have little scientific value 

unless a pygidium can be associated with them. Two 

of the three species discussed here were originated for 

cranidia. Fortunately, pygidia are associated with the 

type specimens so that useful diagnoses can be obtained.

Recent authors (Walcott, 1925; Kobayashi, 1935; 

Lake, 1938; and Rasetti, 1951) have had varying 

opinions about the relationships of Olenoides and 

Neolenus here considered synonyms.

The history of these opinions is well presented by 

Kobayashi (1935, p. 153, 154) and Lake (1938, p. 251- 

254). Most of the writers who expressed opinions, 

including Kobayashi and Lake, did not have the benefit 

of examination of the critical specimens. The following discussion is based upon a study of the genotypes 

of Olenoides and Neolenus.

Because of the fragmental nature of the only known 

specimen of Olenoides nevadensis (Meek), the genotype, 

the only parts capable of comparison with Neolenus 

serratus (Rominger), the genotype, are the thorax and 

pygidium. Meek's and Rominger's specimens are 

crushed but not otherwise distorted. Each specimen 

has seven thoracic segments. The axial lobe of the 

thorax of Rominger's specimen is not well preserved, 

but topotype specimens have a median node on each 

ring as does 0. nevadensis (Meek). The axial lobe of 

N. serratus (Rominger) has a slightly greater rate of 

posterior taper than that of 0. nevadensis ("Meek); 

and accentuating their diagonal nature, the pleural 

furrows of the thoracic segments of Rominger's specimen are narrower than those of 0. nevadensis (Meek).
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 63

The axial lobe of the pygidium of each type specimen 

is made up of four rings and a terminal segment; it 

does not reach the border. The principal differences 

between the specimens are the courses of the pleural 

furrows and interpleural grooves on the pleural platforms. On N. serratus (Rominger) the first pleural 

furrow and groove are nearly identical in their courses 

to those of the preceding thoracic segment. The second, 

third, and fourth pleural furrows make progressively 

smaller angles with the longitudinal axis of the pygidium. Each interpleural groove—the second, third, and 

fourth are discernible—curves more strongly backward 

than the one that precedes it. All segments of the 

pygidium, including that bearing the terminal portion 

of the axial lobe, bear sharp short marginal spines— 

totaling five pairs.

On the pygidium of 0. nevadensis (Meek) the grooves 

and furrows are relatively broader than those of N. 

serratus (Rominger). The first pleural furrow and 

interpleural groove are also nearly identical in their 

courses to those of the preceding thoracic segment. 

The second, third, and fourth pleural furrows also make 

progressively smaller angles with the longitudinal axis 

of the pygidium. The third furrow, however, is 

nearly parallel to the longitudinal axis, and the fourth 

is continuous with the dorsal furrow. The interpleural 

grooves are adjacent to, behind, and parallel to the 

pleural furrows. The fourth groove is not discernible. 

The angle made by the third furrow and groove of 

0. nevadensis (Meek) with the longitudinal axis of 

the pygidium is distinctly smaller than that made by 

the fourth furrow and groove of N. serratus (Rominger). 

The margin of 0. nevadensis (Meek) has been destroyed but probably bore at least four pairs of spines.

If only these two species were involved, a case might 

be made for keeping them in separate genera. Many 

other species of Neolenus and Olenoides have been described, however; and complete gradation between the 

distinctive characters of the two genotypes is present. 

The writer can see no objection to accepting the view 

of Kobayashi (1935, p. 154) that Rominger's and 

Meek's specimens represent distinct species of the 

same genus. In the writer's opinion, therefore, 

Olenoides Meek, 1877 (not Neolenus Matthew, 1899), 

although originated for a wholly inadequate specimen 

by present standards, is the correct designation for 

the genus under discussion.

Olenoides expansus (Walcott) 

Plate 14, figures 5, 7

Dicellocephalus? expansus Walcott, 1884, U. S. Geol. Survey

Mon. 8, p. 45, pi. 9, fig. 19. 

Dclichometopus? expansus (Walcott). Walcott, 1916, Smithsonian Misc. Coll., v. 64, no. 5, p. 368, pi. 53, figs. 5, 5a.

Description.—Walcott (1884, p. 45) described the 

cranidium of this species in considerable detail.

Glabella elongate subquadrangular, or subclavate, the base 

about one-fifth narrower than the front; surface convex and 

without perceptible furrows; occipital furrow distinctly defined; 

occipital ring strong, with a small spine on the center of the posterior portion; dorsal furrows well defined along the sides of the 

glabella; fixed cheeks of medium width, palpebral lobes unknown; an ocular (?) ridge crosses the anterior portion of the 

right fixed cheek, so as to indicate a moderate sized eyelbbe between it and the postero-lateral limb; frontal limb as a narrow 

rim; postero-lateral limbs rather narrow, extended and marked 

by a strong furrow within the posterior margin.

An associated pygidium, lacking the right pleural 

lobe is used for the following description. Pygidium 

subsemicircular in outline. Axial lobe elongate, well 

defined by dorsal furrow, extending nearly to posterior 

margin, consisting of four distinct segments and a partially divided terminal portion, and bluntly rounded 

posteriorly. Dorsal furrows slightly convergent posteriorly adjacent to the two anterior segments, parallel 

behind the second segment. Pleural lobes marked by 

strong pleural furrows and weak interpleural grooves. 

Four pleural furrows and three pleural grooves are 

visible. The fourth pleural furrow makes a sharp 

angle with the dorsal furrow. Anteriorly, the furrows 

make progressively larger angles with the dorsal furrow. The first two interpleural grooves and the last 

two pleural furrows ,end near the margin in distinct 

subcircular depressions. Four pairs of marginal spines 

are present. The two anterior pairs are moderately 

long and slender. The third pair is more than twice 

the length and diameter of the anterior spines. The 

fourth pair is represented by small nubs along the 

margin.

The surface of the specimen is smooth.

Discussion.—The pygidium of this species has not 

previously been described. A pygidium bearing the 

same museum and locality numbers as the type cranidium is associated with it in the U. S. National Museum 

collections. On the basis of this association, the assignments of the species, by Walcott (1916, p. 368) to 

Dolichometopus and by Kobayashi (1942, p. 152) to 

Dolichometopsis (Ptarmigania) , are incorrect and only 

serve to illustrate the difficulty of accurate systematic 

placement of cranidia of the Dorypygidae without 

knowledge of the associated pygidia. Resser (1938b, 

p. 37) assigned the species to Olenoides, but without 

giving any explanation for his decision.

The distinguishing characteristics of the species are 

the axial lobe of the pygidium, which consists of four 

segments and a partially divided terminal portion, the 

strong development of the thircl pair of marginal spines, 

and the weak development of the fourth pair.
64 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Occurrence.—Middle Cambrian, Geddes limestone of 

Wheeler and Lemmon (1939) Eureka district, Nev.

Figured specimens.—Cranidium, USNM 15450, 

length, 13 millimeters; pygidium, USNM 15450, length, 

14 millimeters.

Olenoides nevadensis (Meek) 

Plate 14, figure 9

Paradoxides? nevadensis Meek, 1870, Acad. Nat. Sci. Philadelphia

Proc., p. 62. 

Meek, 1877, U. S. Geol. Expl. 40th Par. Kept. v. 4, p. 23,

pi. 1, fig. 5. 

Olenoides nevadensis (Meek), Walcott, 1886, U. S. Geol. Survey

Bull. 30, p. 181, pi. 25, fig. 7. 

Walcott, 1913, Carnegie Inst. Washington Pub. 54, v. 3, pi.

8, fig. 7.

Shinier and Shrock, 1944, Index Fossils of North America, 

pi. 256, fig. 18.

Discussion.—The type and only known specimen is 

discussed under the genus. The distinctive characteristics of the species are the axial lobe, which consists of 

four segments and a terminal portion, and the sharp 

angle made by the third pleural furrow with the longitudinal axis of the pygidium.

Occurrence.—Middle Cambrian, Wheeler formation, 

House Range, Utah.

Figured specimen.—Holotype, incomplete carapace, 

USNM 15453, length, 69 millimeters.

Olenoides wahsatchensis (Hall and Whitfield) 

Plate 14, figures 6, 8

Dikellocephalus wahsatchensis Hall and Whitfield, 1877, U. S.

Geol. Expl. 40th Par. Rept., v. 4, p. 241, pi. 1, fig. 35. 

Dikellocephalus? gothicus Hall and Whitfield, 1877, idem, p. 242,

pi. 1, fig. 36. 

Olenoides wahsatchensis (Hall and Whitfield), Walcott, 1886,

U. S. Geol. Survey Bull. 30, p. 189, pi. 29, figs. 2, 2a. 

Resser, 1939, Smithsonian Misc. Coll., v. 97, no. 12, p. 14,

pi. 4, figs. 1, 2.

Description.—Hall and Whitfield (1877, p. 241, 242) 

described this species in considerable detail.

Glabella elongate-quadrangular, with parallel lateral margins 

and slightly-rounded front; height and width about as four to 

three; very depressed-convex, and marked by two pairs of 

transverse furrows, which do not quite meet in the center, 

dividing the glabella into three nearly equal portions. Occipital 

furrow narrow, not strongly defined; ring narrow, distinct, and 

bearing a slender spine on the center; dorsal furrows narrow and 

poorly defined.

Fixed cheeks wide and flattened; ocular ridges faintly marked, 

rising opposite the anterior furrow of the glabella, and directed 

slightly backward to the eye-lobe. Frontal limb very short and 

wide, the marginal rim regularly arcuate, narrow, and prominent, 

closely cutting the front of the glabella. Facial sutures not 

fully determined, but are distinct on the anterior margin, cutting 

the rim with a strong outward curvature, and again recurving 

to the eye, leaving the limb nearly two-thirds as wide at its 

widest point as the glabella.

Pygidium semi-ovate, or short paraboloid, with a very strong 

central axis, and spinose margin; anterior margin straightened 

for about two-thirds the width of the lateral lobes, where it 

curves abruptly backward to the lateral angles. Axial lobe 

strong, cylindrical, and prominent, forming one-third of the 

entire width exclusive of the spines, and reaching almost to the 

posterior margin of the shield; obtusely rounded at the extremity, 

and marked by six annulations exclusive of the terminal ones. 

Lateral lobes very moderately convex, and marked by four 

divided ribs on each side, each terminating in a strong and proportionally long marginal spine; central area of each rib depressed, forming a flattened groove, extending to the base of 

the marginal spine. Borders of the ribs elevated, the anterior' 

one strongest and prominent, gradually widening from its origin 

to the margin of the shield; posterior border narrow and rounded, 

separated from the next succeeding rib by a sharply-depressed, 

narrow groove. This peculiar form of rib gives to the shield an 

appearance similar to the groining of a Gothic arch. Margin 

of the shield surrounded by twelve long, rather strong spines, 

four of which, on each side, are about equal in size and strength, 

while the four occupying the posterior border are shorter and 

unequal, those in the middle being the shortest.

Discussion.—Walcott (1886, p. 189) pointed out that 

Dikellocephalusf gothicus Hall and Whitfield is the 

pygidium of 0. wahsatchensis (Hall and Whitfield). There 

are several features of the original descriptions of this 

and the cranidium that are not accurate. The glabellar 

furrows are depressions, owing primarily to crushing. 

Well-preserved specimens probably would exhibit only 

shallow furrows if any at all. There are 5 rather than 

6 axial segments exclusive of the terminal one on the 

pygidium. The original authors apparently considered 

the articulating ring of the first segment as a separate 

segment.

The pygidium is similar to 0. serratus (Rominger), 

differing in having one more axial segment and one more 

pair of marginal spines. The four long lateral pairs 

of spines and two short posterior pairs distinguish this 

species from others with six pairs of spines.

Occurrence.—Middle Cambrian, Spence shale member of Ute limestone Wasatch Range, Utah.

Figured specimens.—Holotype cranidium, USNM 

15447, length, 15 millimeters; pygidium, USNM 

15447, length (not including spines), 15 millimeters.

Genus EOOTENIA Walcott, 1889

Kootenia Walcott, 1888, Am. Jour. Sci. 3d ser., v. 36, no. 213,

p. 446.

Walcott, 1925, Smithsonian Misc. Coll., v. 75, no. 3, p. 92. 

Kobayashi, 1935, Tokyo Imp. Univ., Fac. Sci., Jour., sec.

2, v. 4, pt. 2, p. 156. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 613.

Genotype.—Bathyuriscus (Kootenia) dawsoni Walcott, 

1889 (p. 446).

Diagnosis.—Like Olenoides but with only pleural 

furrows visible on the pleural platforms of the pygidium.
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 65

Kootenia quadriceps (Hall and Whit field) 

Plate 14, figures 1-3

Dikellowphalus quadriceps Hall and Whitfield, 1877, U. S.

Geol. Expl. 40th Par. Rept.,'v. 4, p. 240, pi. 1, figs. 37-40. 

Olenoides quadriceps (Hall and Whitfield), Walcott, 1886, U. S.

(jeol. Survey Bull. 30, p. 187, pi. 29, figs. 1, la-c. 

Olenoides quadriceps (Hall and Whitfield), Walcott, 1890, U. S.

Geol. Survey 10th Ann. Kept. pt. 1, p. 646, pi. 94, figs.

4-., 4a-b.

Description.—Hall and Whitfield (1877, p. 240) 

described this species in considerable detail.

Glabella and fixed cheeks united, quadrangular in form, with 

a regularly and symmetrically arcuate front margin. Glabella 

elongate quadrangular, a little expanded and rounded in front, 

three-fourths as wide across the middle as the length above the 

occipital furrow, very gibbous or somewhat inflated; marked by 

three pairs of transverse furrows, which extend about threefourths of the distance to the center, not in the least oblique, and 

so faint as to be detected only on the closest examination, or by 

the reflection of light along the surface; occipital furrow very 

distinct; ring strong and robust, supporting a strong, thickened 

spine of undetermined length on the posterior margin. The base 

of the spine is broad, and the spine directed backward and 

upward,

Fixed cheeks of moderate size, strongly convex, a little more 

than one-third as wide at the eye as the width of the glabella, 

and rapidly declining to the antero-lateral angles. Eye-lobes 

small, situated rather behind the middle of the length of the 

head; ocular ridges distinct, strongly directed forward in their 

passage from the eye to the glabella. Frontal limb very short, 

not extending beyond the frontal margin of the glabella, and 

strongly curving backward to the point of intersection with the 

facial sutures.

Facial sutures commencing at the anterior margin on a line 

with the inner angle of the eye-lobe, and running directly back 

to the eye in a straight line; behind the eye, the direction is 

outward, but its exact course has not been ascertained. Lateral 

limb nob observed.

A pygidium associated with the glabella is paraboloid in form, 

and surrounded on the margins by twelve short, rather strong 

spines, the four on the posterior margin being shorter than the 

others. Axis narrow, highly convex, two-thirds as long as the 

shield, £i,nd marked by four rings, exclusive of the terminal ones. 

Lateral lobes broad, convex, and marked by four low, rounded 

ribs, the anterior one much narrower than the others; each of 

the four ribs terminating in one of the lateral spines.

Discussion.—As pointed out by the original authors, 

this species is similar to Dikellocephalus? gothicus Hall 

and T^hitfield (—Olenoides wahsatchensis (Hall and 

Whitfield.)) The principal distinguishing feature is 

the shallow nature of the interpleural grooves on the 

pygidium. D. quadriceps Hall and Whitfield was 

placed in Kootenia by Resser (1937, p. 16) without 

comment.

The specimen from the Eureka district, Nev., figured as Dikellocephalus? quadriceps Hall and Whitfield 

by Walcott (1884, pi. 9, fig. 24) is a small fragmentary 

cranidium that may not belong to the species. Resser 

(1937, p. 15) placed it in a new species Kootenia eurekensis Resser, but until a pygidium is found there is no 

assurance that it even belongs in Kootenia. His diagnosis, "Compared with K. quadriceps this species is 

much shorter.", is totally inadequate. The significance 

of slight differences in proportion in such small samples 

is open to serious question. K. eurekensis Resser 

definitely differs from K. quadriceps (Hall and 

Whitfield) by lacking an occipital spine; but, in terms 

of present knowledge of trilobites of this family, more 

information than that is needed to erect a new species. 

Taxonomically speaking, Walcott's specimen is specifically and generically unidentifiable. For this reason 

the name Kootenia eurekensis Resser, 1937, should be 

restricted to the holotype numbered 15449 in the 

collections of the U. S. National Museum.

Occurrence.—Middle Cambrian, Ute limestone, Bear 

River Range, Utah.

Figured specimens.—Co types: Cranidium, USNM 

15448a, length, 6.5 millimeters; pygidium, USNM 

15448b, length (not including spines) 8.5 millimeters; 

pygidium, USNM 15448c, length (not including spines) 

10 millimeters.

Genus HOLTERIA Walcott, 1924

Holteria Walcott, 1924, Smithsonian Misc. Coll., v. 75, no. 2,

p. 57.

Walcott, 1925, idem, no. 3, p. 91. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 611.

Genotype.—Ogygia? problematica Walcott, 1884 (p. 63, 

pi. 10, figs. 2, 2a, b, 4).

Diagnosis.—Cranidium like Olenoides Meek. It differs from typical forms of that genus by having the 

anterior end of the glabella overhanging the anterior 

margin, a shallow occipital furrow, but no occipital 

spine.

Pygidium with axial lobe moderately well defined, 

narrow, three-fourths or more the length of pygidium, 

consisting of four segments and a rounded terminal 

portion. Pleural lobes consisting of four segments; 

distinct pleural furrows and interpleural grooves present; pleural furrows parallel and adjacent to groove 

marking posterior margin of each pleural segment. 

First and second pleural segments rapidly expanding 

distally, second segment largest, and extended into 

moderately long, straight, posterolaterally directed 

marginal spines; second pair of marginal spines originates posterior to end of axial lobe. Third pleural segment narrower than second segment; pleural furrow 

and interpleural groove nearly parallel to dorsal 

furrow. Fourth pleural segment, when discernable, 

less than one-third width of third segment, poorly 

defined, approximately parallel to dorsal furrow. 

Third and fourth segments not extended into marginal
66 SHOKTBK CONTRIBUTIONS TO GBNEKAL GEOLOGY

spines. Posterior margin of pygidium between spines , 

of second pleural segment, curved gently forward.

Discussion,—The cranidium of this genus resembles 

that of Olenoides inflatus (Walcott) (1908, p. 30). It 

differs .principally by lacking a strong occipital spine. 

The pygidium is unlike that of any other known trilobite. Walcott (1925, p. 92) stated that this was an 

Upper Cambrian genus. The associated trilobite fauna 

does not support his conclusion. Modocia nevadensis 

Palmer, n. sp., and Asaphiscus laeviceps (Resser) are 

congeneric or conspecific with trilobites from the Middle 

Cambrian Secret Canyon shale. Only Kormagnostus 

sedusus (Walcott) has Upper Cambrian affinities.

Holteria problematica (Walcott) 

Plate 15, figures 3, 4, 6

Ogygiaf problematica Walcott, 1884, U. S. Geol. Survey Mon.

8, p. 63, pi. 10, figs. 2, 2a, b, 4. 

Holteria problematica (Walcott). Walcott, 1924, Smithsonian

Misc. Coll., v. 75, no. 2, p. 57, pi. 13, fig. 7. 

Walcott 1925, idem, v. 3, p. 93, text fig. 13; pi. 15, figs.

17-21.

Shimer and Shrock, 1944, Index Fossils of North America, 

pi. 259, figs. 20, 21.

Diagnosis.—As this is the only described species of 

the genus, its characters are those of the genus.

Discussion.—The two pairs of broad marginal spines 

and the character of the segmentation on the pleural 

lobes of the pygidium distinguish this species from all 

other known trilobites.

Occurrence.—Middle Cambrian, lower part of the 

Hamburg limestone, Eureka district, Nev.

Figured specimens.—Cotypes: Immature cranidium, 

USNM 24606, length, 3 millimeters; adult cranidium, 

USNM 24606, length, 23 millimeters; pygidium, USNM 

24606, length, 19 millimeters.

Family DOLICHOMETOPIDAE Walcott, 1916 

Genus ATHABASKIA Raymond, 1928

Athabaskia Raymorid, 1928, Am. Jour. Sci. 5th ser., v. 15, no.

88, p. 311. 

Kobayashi, 1942, Tokyo Imp. Univ., Fac. Sci. Jour., sec.

2, v. 6, pt. 10, p. 156. 

Lochman, 1952, Smithsonian Misc. Coll., v. 119, no. 1,

p. 128.

Genotype.—Athabaskia ostheimeri Raymond, 1928 (p. 

311).

Diagnosis.—Cephalon subsemicircular in outline; 

posterior margin straight; distinct genal spines extend 

backward from posterolateral corners. Cranidium with 

glabella extending to or nearly to anterior margin, 

straight sided behind next to last glabellar furrow, 

distinctly expanded anterior to this furrow; anterolateral corners strongly rounded; anterior margin broadly 

rounded. Three pairs of straight glabellar furrows visible; posterior pair extended backward at a sharp angle

with dorsal furrow; middle pair approximately perpendicular to dorsal furrow; anterior pair extended forward 

from dorsal furrow. Occipital furrow distinct, deepest 

at sides. Occipital ring flat, unspined. Width of fixed 

cheeks about one-third width of glabella. Palpebral 

lobes long, distinct; anterior ends nearly touching dorsal 

furrow in front of first distinct glabellar furrow. Posterior limbs longer than occipital ring, narrow.

Thorax of 7 or 8 segments. Axial lobe narrower than 

pleural lobes. Pleural lobes of each segment subequally 

divided by broad pleural furrow and extended distally 

into a short pointed spine.

Pygidium subsemicircular in outline, nearly as large 

as cephalon. Axial lobe prominent, furrowed, about 

as wide as pleural platforms, not extended onto concave 

border. Pleural lobes with pleural furrows and interpleural grooves about equally spaced, usually extended 

onto border.

Discussion.—The cranidium of this genus is similar 

to that of Bathyuriscus and for this reason Kobayashi 

(1942, p. 156) considered it only a subgenus of Bathyuriscus. Resser (1935, p. 20) placed the genus in 

synonymy with Clavaspidella. The writer agrees with 

Rasetti (1951, p. 156) and Lochman (1952, p. 128) who 

have considered Athabaskia to be distinct from both 

Bathyuriscus and Clavaspidella. The relationships of 

the genus to Clavaspidella are discussed and analysed 

by Lochman (1952, p. 128).

Athabaskia howelli (Walcott) 

Plate 13, figure 8

Bathyuriscus howelli Walcott, 1886, U. S. Geol. Survey Bull. 30,

p. 216, pi. 30, figs. 2, 2a. 

Pack, 1906, Jour. Geology, v. 14, no. 4, p. 296, pi. 2, figs.

2, 2a. 

Walcott, 1916, Smithsonian Misc. Coll., v. 64, no. 5, p. 343,

pi. 47, figs. 1, Ib.

Clavaspidella howelli (Walcott). Shimer and Shrock, 1944, Index 

Fossils of North America, p. 609, pi. 259, fig. 3.

Description.—Walcott (1886, p. 216) described this 

species in considerable detail.

General form ovate. Entire form of head unknown, but from 

the parts preserved it appears to have been semicircular. Glabella clavate, expanding in front of the second pair of glabellar 

furrows; posteriorly the sides are subparallel to the occipital 

segment; the posterior pair of glabellar furrows are directed 

obliquely backward nearly to the occipital furrow; the second 

pair are less obliquely inclined backward, and the third pair 

penetrate directly in, one-third the distance on each side. 

Occipital furrow well defined; occipital ring rounded and rather 

strong. Eyes large, lunate, the extremities close to the glabella. 

Fixed cheeks very narrow; postero-lateral limbs narrow elongate; 

frontal limb narrow, slightly convex, and expanding but little 

in front of the glabella. The facial sutures cut the anterior 

margin and trend obliquely in to the anterior end of the eyes; 

encircling the large palpebral lobes, they extend outward from 

the posterior ends of the eyes and cut the posterior margin of
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 67

the head well out towards the genal angle. Free cheeks unknown.

Thorax with eight segments. Axial lobe convex, tapering very 

gradually from the anterior segments to the pygidium; each 

segment is well defined and arches slightly forward; pleural lobes 

moderately convex; the segments curve gently backward from 

the genal angle and terminate in short falcate points; pleural 

groove rather broad and deep, and continued nearly to the 

extremity of the segment.

Pygidium subelliptical in outline; axis prominent, elongate, 

subconical, divided by four transverse furrows into four rings 

and a terminal segment; the pleural lobes are less convex, and, 

towards the margin, flattened out so as to form a broad, slightly 

convex border across which the four anchylosed segments, with 

their pleural grooves well defined, extend nearly to the margin.

Surface not preserved so as to show any surface striae.

Dimensions: Length of entire body, 23 mm; head, 9 mm; 

thorax, 8 mm; pygidium, 6 mm.

Discussion.—This species is characterized by having 

the anterior ends of the palpebral lobes reaching nearly 

to the dorsal furrow and the border of the pygidium 

about as wide as the greatest width of the pleural 

platform.

Occurrence.—Middle Cambrian, Chisholm shale, 

Pioche, Nev.

Figured specimen.—Holotype, USNM 15457, length, 

23 millimeters.

Genus GLOSSOPLEURA Poulsen, 1927

Glossopleura Poulsen, 1927, Meddelelser om Gronland, Bind 70,

p. 268. 

Kobayashi, 1935, Tokyo Imp. Univ., Fac. Sci., Jour., sec.

2, v. 4, pt. 2, p. 132.

Kobayashi, 1942, idem, v. 6, pt. 10, p. 159. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 611.

Sonoraspis Stoyanow, 1952, Smithsonian Misc. Coll., v. 119, no. 

1, p. 50.

Genotype.—Dolichometopus boccar Walcott, 1916 (p. 

363, pi. 52, figs. 1, la-f).

Diagnosis.—Cephalon subsemicircular in outline; 

posterior margin straight; distinct genal spines extend 

backward from posterolateral corners. Cranidium with 

glabella moderately well to poorly defined by dorsal 

furrow, extended to anterior margin, slightly expanded 

forward or of nearly constant width. Glabellar furrows 

shallow or absent; when visible, four pairs usually 

present. Occipital furrow shallow. Occipital ring flat, 

unspined. Border absent. Brini, when present, narrow, only at sides of glabella. Fixed cheeks about onehalf width of glabella; palpebral lobes long, poorly 

defined; anterior ends nearly touching dorsal furrow, 

posterior eads about opposite occipital furrow. Posterior limbs narrow, about as long as occipital ring; 

marginal furrow shallow.

Free cheek with evenly rounded margin and promi296334—54——3

nent genal spine. Border differentiated from ocular 

platform, variable in width.

Thorax of 7 or 8 segments. Axial lobe prominent, 

width equal to or less than that of pleural lobes. 

Pleural lobes of each segment subequally divided by 

pleural furrow. Segments terminate distally in short, 

sharp spines.

Pygidium subsemicircular in outline about as large 

as cephalon. Axial lobe prominent, tapered slightly 

posteriorly, reaching to or onto broad, flat or concave 

border. Furrows on axial and pleural lobes shallow or 

absent.

Discussion.—This genus is characterized by the 

shallow nature of all furrows on the cephalon and 

pygidium, the poorly developed frontal area, long 

palpebral lobes on the- cranidium, and the broad flat 

or concave border on the pygidium.

Sonoraspis (Stoyanow, 1952, p. 50) is based on 

poorly preserved material that differs from Glossopleura 

by having 8 instead of 7 thoracic segments. The writer 

does not consider this sufficient justification for generic 

distinction, especially with the inadequate knowledge 

available concerning variation of this feature within 

a population. Sonoraspis is considered here to be a 

synonym of Glossopleura.

Glossopleura producta (Hall and Whitfield) 

Plate 13, figures 7, 9-13

Ogygia producta Hall and Whitfield, 1877, U. S. Geol. Expl. 40th

Par. Rept. v. 4, p. 244, pi. 2, figs. 31-34. 

Ogygia parabola Hall and Whitfield, 1877, idem, p. 245, pi. 2,

fig. 35. 

Bathyuriscus productus (Hall and Whitfield). Walcott [part],

1886, U. S. Geol. Survey Bull. 30, p. 217, pi. 30, figs.

le, If, and li. 

Dolichometopus productus (Hall and Whitfield). Walcott [part],

1916, Smithsonian Misc. Coll., v. 64, no. 5, pi. 53, figs.

2, 2a-e.

Description.—Glabella elongate, slightly expanded 

forward, reaching to anterior margin, bearing slight 

median longitudinal keel, well defined by dorsal furrow. 

Glabellar furrows indistinct. Occipital furrow broad, 

moderately deep. Occipital ring broad. Character of 

brim in front of palpebral lobes not known. Fixed 

cheeks about one-half of glabella on line through midpoints of palpebral lobes. Palpebral lobes about twothirds length of glabella, narrow, curved, slightly 

depressed below level of cheek, anterior ends adjacent to 

dorsal furrow, posterior ends opposite occipital furrow 

about one-third width of glabella from dorsal furrow. 

Posterior limbs about equal in length to occipital ring, 

narrow. Marginal furrow broad, shallow.

Free cheek elongate subtriangular in outline, margin 

gently curved. Border narrow, separated from broad
68 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

ocular platform by shallow marginal furrow. Faint 

suggestion of a genal spine. Eyes large, situated 

towards anterior end of cheek.

Thorax subquadrate in outline, consisting of seven 

segments. Axis tapered slightly backward, well defined by dorsal furrow, somewhat less than one-third 

width of thorax. Pleural lobes of each segment flattened and pointed distally. Pleural furrows broad, 

shallow, situated slightly anterior to middle of segment.

Pygidium subsemicircular in outline. Axis elongate, 

well defined by dorsal furrow, reaching to or onto concave border, anterior width slightly more than onefourth that of pygidium. Axial segments 6 or 7 poorly 

defined. Pleural platforms faintly furrowed. Border 

concave, of nearly constant width, slightly less than 

one-third width of pleural lobe at anterior margin.

Discussion.—It is unfortunate that some of the oldest 

name-bearing trilobite specimens are represented by 

such poor material as is G. producta (Hall and Whitfield). 

The type cranidium is laterally compressed, lacks the 

anterolateral margins and posterior limbs, and shows 

only broken portions of the fixed cheeks. The pygidium 

is longitudinally compressed but is otherwise in relatively good condition. Laterally compressed pygidia 

in the same collection have an entirely different appearance as pointed out by Walcott (1886, p. 218). Ogygia 

parabola Hall and Whitfield, from the same beds as 

0. producta Hall and Whitfield, is a laterally compressed 

pygidium of that species. Because of the distorted 

nature of the compressed shale specimens, specific 

comparisons have little value.

It is not the purpose of this paper to review the 

numerous species assigned to Glossopleura in the past 

two decades. Resser was certainly correct in assigning 

Ogygia producta Hall and Whitfield to the genus. In 

fact, the differences between G. producta Hall and Whitfield and the genotype G. boccar (Walcott), also represented by poor material, are so slight as to raise the 

question of their recognition as different species. For 

the purposes of accurate paleontology and until the 

species is described from better material, the use of the 

name Glossopleura producta (Hall and Whitfield) should 

be confined to the type specimens.

Occurrence.—Middle Cambrian, Ophir shale?,. 

Oquirrh Range, Utah.

Figured specimens.—Cotypes: Incomplete carapace, 

USNM 15456c, length, 33 millimeters; cranidium, 

USNM 15456a, length, 17 millimeters; pygidium, 

USNM 15456e, length, 13 millimeters; free cheek, 

USNM 15456b, width, 12 millimeters. Other specimens: Incomplete carapace, USNM 123356, length, 25 

millimeters; holotype of 0. parabola, USNM 15456d, 

length, 24 millimeters.

Family ORYCTOCEPHAIIDAE Beecher, 1897 

Genus ORYCTOCEPHALUS Walcott, 1886

Oryctocephalus Walcott, 1886, TJ. S. Geol. Survey Bull. 30, p.

210. 

Reed, 1910, India Geol. Survey Mem., ser. 15, v. 17, mem.

1. p. 10. 

Kobayashi, 1935, Tokyo Imp. Univ., Fac. Sci., Jour., sec.

2. vol. 4, pt. 2, p. 146.

Shinier and Shrock, 1944, Index Fossils of North America, 

p. 615.

Genotype.—Oryctocephalus primus Walcott, 1886 (p. 

210, pi. 29, figs. 3, 3a).

Diagnosis.—Cranidium with glabella prominent, 

nearly parallel sided, extended to border. Glabellar 

furrows marked by three pairs of pits often connected 

by shallow furrows across top of glabella but not connected to dorsal furrow. Occipital furrow distinct, 

.with deep pits near dorsal furrow. Brim not present 

in front of glabella. Border flat, short. Width of 

fixed cheek one-half or more width of glabella. Palpebral lobe moderately large, opposite middle third of 

glabella, connected to dorsal furrow by distinctly to 

poorly defined ocular ridge. Facial suture straight forward in front of palpebral lobe, divergent behind.

Free cheek narrow, margin evenly rounded. Border 

well defined by marginal furrow, extended posteriorly 

into genal spine.

Thora,x of 6 or 7 segments. Axial lobe prominent, 

width greater than one-half width of pleural lobes. 

Pleural lobe of each segment with deep diagonal pleural 

furrow; distal spines of variable length.

Pygidium subsemicircular in outline, consisting of 5 

segments and a small terminal portion. All segments 

visible on axial and pleural lobes; pleural furrows deeper 

than interpleural grooves. Each segment extended 

distally into a marginal spine.

Discussion.—The cranidium of this genus is characterized by the elongate glabella with three pairs of pits 

representing the glabellar furrows. The pygidium, 

which has the principal diagnostic generic features, 

differs from the pygidia of other members of the family 

by having pleural furrows, interpleural grooves visible, 

and marginal spines.

Oryctocephalus primus Walcott 

Plate 15, figures 1, 2

Oryctocephalus primus Walcott, 1886, TJ. S. Geol. Survey Bull.

30, p. 210, pi. 29, figs. 3, 3a.

Walcott, 1890, U. S. Geol. Survey 10th Ann. Kept., pt. 1, 

p. 653, pi. 95, figs. 4, 4a.

Diagnosis.—Pygidium with long, slender marginal 

spines.

Description.—Walcott (1886, p. 210) described this 

species in considerable detail as follows:

Entire head as restored by the union of the free cheeks to the
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 69

central portions of the head, transverse subsemicircular. Glabella 

elongate, quadrilateral, sides parallel, front broadly rounded and, 

in some specimens, showing a slight indentation midway; surface 

marked by four transverse furrows that terminate in little pits 

within the margin of the glabella; a shallow depression unites the 

pits on each side within the margin, and there is on some glabellas 

a very shallow depression running obliquely backward from each 

pit to the axial furrow; the transverse furrows uniting the pits 

are strong and arch a little backward at the center; anteriorly 

a shallow pit occurs a little back of the antero-lateral angles of 

the glabella that opens out into the axial furrows; the occipital 

furrow is represented by the posterior pair of pits and connecting 

furrow, and the strong occipital segment is united to the glabella 

at each end within the axial furrows; axial furrows strongly 

defined.

Fixed cheeks nearly as broad as the glabella; they narrow 

slightly in front and broaden out posteriorly into the short 

postero-lateral limbs; frontal limb practically obsolete; a narrow 

raised margin borders the front of the head; palpebral lobe 

narrow and with a deep groove between it and the fixed cheek; 

a narrow ocular ridge crosses the fixed cheek from the palpebral 

lobe to the axial groove.opposite the small anterior depressions 

on the side of the glabella. Free cheeks elongate, convex, bordered by a narrow rounded rim that extends backward as a 

short spine; visual surface of eye broken away.

Thorax unknown.

Associated pygidium with a strong axial lobe and divided into 

five rings and into a terminal elongate ring by five transverse 

furrows; pleural lobes strongly grooved by four anchylosed 

pleural segments that terminate in strong, elongate points; a 

fifth segment terminates in a point on each side of the posterior 

end of the axial lobe.

Discussion.—This is the only species occurring with 

Kochaspis lUiana Walcott arid K. augusta Walcott at 

their type locality.

Occurrence.—Middle Cambrian, Pioche formation, 

Pioche, Nev.

Figured specimens.—Cotypes: Cranidium, USNM 

15427, length, 5 millimeters; pygidium, USNM 15427, 

length (not including spines) 5 millimeters.

Family ZACANTHOIDIDAE Swinnerton, 1915 

Genus ZACANTHOIDES Walcott, 1888

Embolimus Rominger, 1887 [not Embolemus Westwood, 1833—

Hymenoptera], Acad. Nat. Sci. Philadelphia Proc., p. 15.

Zacanthoides Walcott, 1888, Am. Jour. Sci. 3d ser., v. 36, no. 213,

p. 165. 

Kobayashi, 1935, Tokyo Imp. Univ., Fac. Sci., Jour., sec.

2, vol. 4, pt. 2, p. 123 [synonymy].

Shinier and Shrock, 1944, Index Fossils of North America, 

p. 619.

Genotype.—Embolimus spinosa Rominger, 1887 (p. 

15, pi. l,fig. 3).

Diagnosis.—Cephalon subsemicircular in outline; 

posterior margin straight; long genal spines extend outward and backward from lateral margins; short intergenal spines may be present at distal ends of posterior 

limbs on cranidium.

Cranidium with glabella moderately well defined by 

dorsal furrow, parallel sided, slightly expanded forward

or slightly tapered forward, not reaching to anterior 

margin. Glabellar furrows variable in depth, 3 or 4 

pairs usually visible. Occipital furrow distinct, straight. 

Occipital ring flat, with or without occipital spine. 

Frontal area short, broad, with depressed brim and 

raised border. Fixed cheeks about one-half width of 

glabella, semicircular hi outline. Palpebral lobes 

narrow, well defined by palpebral furrow, long, curved; 

anterior ends adjacent to dorsal furrow opposite third 

pair of glabellar furrows anterior to occipital furrow; 

posterior ends opposite occipital furrow, about one-third 

width of glabella from dorsal furrow. Posterior limbs 

narrow, about as long as occipital ring, often with 

distinct, posteriorly directed spines at distal extremities. 

Facial sutures widely divergent anterior and posterior 

to palpebral lobe.

Free cheek with evenly rounded margin and distinct, 

narrow border. Long, slender genal spine directed 

outward and backward from lateral margin.

Thorax of 8 or 9 segments. Axial lobe as wide or 

wider than pleural lobes exclusive of spines. Pleural 

portion of each segment with two laterally converging 

marginal furrows that leave a triangular raised median 

portion near the dorsal furrow. Each segment extended 

distally into a long slender spine.

Pygidium smaller than cephalon with prominent 

furrowed axial lobe occupying one-third or more width 

of pygidium, extended nearly to posterior margin. 

Anterolateral corners of pygidium strongly rounded. 

Posterior margin with three or more pairs of posteriorly 

directed spines of varying lengths.

Discussion.—Although this genus has been mentioned 

by many authors who have in some instances added 

new species, it has never been fully defined or described. 

Nevertheless, there has been general agreement concerning its characteristics. The anterior flaring of the 

facial sutures and the long, slender, curved palpebral 

lobes on the cranidium, and the broad thoracic and 

pygidial axes, and spined posterior margin of the 

pygidium are distinctive of the genus. Individual 

cranidia resemble those of Albertella Walcott, Fieldaspis 

Rasetti and Stephenaspis Rasetti, but complete specimens can be recognized by the multispinose margin of 

the pygidium.

There is some confusion about the type of this genus. 

Most workers have cited Ogygiaf spinosa Walcott as 

genotype, but Embolimus spinosa Rominger from the 

Stephen formation of British Columbia is the species 

that should be cited. Walcott (1888, p. 165) proposed 

Zacanthoides to replace Embolimus Rominger (1887, 

p. 15), which was occupied by Embolemus Westwood, 

1833. The only species of Embolimus Rominger that 

was retained in Zacanthoides was E. spinosa Rominger,
70 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

1877. This species automatically became the genotype 

of Zacanthoides.

Walcott, however, considered E. spinosa Rominger 

a junior synonym of O.f spinosa Walcott, 1884, thus 

making O.f spinosa, Walcott the name of the genotype 

species. Resser, 1935, considered Rominger's and 

Walcott's species to be different and proposed Z. 

romingeri Resser to replace the specific name spinosa, 

which was occupied by that of Walcott's species. The 

genotype of Zacanthoides therefore is Embolimus 

spinosa Rominger (=Z. romingeri Resser) the species 

originally described by Rominger for Embolimus, 

(name replaced by Zacanthoides by Walcott).

Zacanthoides spinosus (Walcott) 

Plate 15, figures 5, 7

Ogygia? spinosa Walcott, 1884, U. S. Geol. Survey Mon. 8, p.

63, pi. 9, fig. 22. 

Olenoides spinosus (Walcott), Walcott [part], 1886, U. S. Geol.

Survey Bull. 30, p. 184, pi. 25, fig. 6.

Description.—The cranidium of this species was described in detail by Walcott (1884, p. 63).

Glabella elongate, not quite twice as long as wide; sides 

parallel nearly to the front, which is slightly expanded and 

broadly rounded anteriorly; moderately convex and subangular 

along the median line; marked by three pairs of oblique furrows 

that extend one-third the distance across; occipital ring strong, 

not very convex, and with a rather strong central spine projecting 

backward and upward; occipital furrow shallow, well defined; 

fixed cheeks narrow; palpebral lobes large, rising slightly from 

the dorsal furrows to the depressed furrow just within and 

parallel to their margins; frontal limb convex, of medium width 

and length, and bordered by a flattened rim. The presence of 

the strong occipital spine is one of the most distinct characters 

of this species.

Pygidium subquadrate in outline, somewhat wider 

than long. Axis well defined, elevated above pleural 

lobes, parallel sided, bluntly terminated, reaching to 

border, bearing three distinct axial segments. Pleural 

lobes flat, three pairs of pleural segments distinguishable. Interpleural grooves broad, shallow. Pleural 

furrows narrow. Margin with four pairs of short flat 

spines of nearly equal size and length and a fifth inner 

pair about half the size of the others.

Discussion.—The cranidium of Z. spinosus (Walcott) 

is similar in nearly all of its observable characters to 

Z. typicalis (Walcott), differing only in the glabella, 

which is slightly expanded and more bluntly terminated 

anteriorly. The pygidium, from about the same horizon as the described cranidium, is unique in the character of the marginal spines which are unlike those of any 

other species of Zacanthoides.

Occurrence.—Middle Cambrian, Geddes limestone of 

Wheeler and Lemmon (1939) Eureka district, Nev.

Figured specimens.—Holotype cranidium, USNM 

15451, length (not including spines), 20 millimeters;

pygidium, USNM 123352, length (not including spines), 

8 millimeters.

Zacanthoides typicalis (Walcott) 

Plate 15, figure 9

Olenoides typicalis Walcott, 1886, U. S. Geol. Survey Bull. 30,

p. 183, pi. 25, figs. 2, 2a. 

Zacanthoides typicalis (Walcott), Pack, 1906, Jour. Geol., v. 14,

no. 4, p. 299, pi. 3, figs. 2-2f. 

Walcott, 1913, Carnegie Inst. Washington Pub. 54, pi. 24,

fig. 2.

Shinier and Shrock, 1944, Index Fossils of North America, 

p. 619, pi. 257, figs. 20-22.

Description.—This species was described in considerable detail by Walcott (1886, p. 183).

Form ovate. Head large, semicircular in outline. Glabella 

elongate, not quite twice so long as wide; sides subparallel; front 

broadly rounded; general surface moderately convex and marked 

by four pairs of glabellar furrows that extend about one-third 

the distance across, the anterior being scarcely discernable in 

most specimens; occipital furrow well defined; occipital ring 

strong, not very convex, and with a rather strong central spine 

projecting backwards over the thorax.

Fixed cheeks broad inside the rim of the eye, contracted at 

the front of the eye and expanding to unite with the frontal limb, 

which is of medium width, concave, and bordered by a narrow, 

rim-like margin; postero-lateral limbs narrow, elongate, with a 

central longitudinal ridge and a rather long spine extending 

backward just within the extremity of the limb. Free cheeks 

large, bordered exteriorly by a rather thick rim that is produced 

into a strong genal spine. Eyes narrow, elongate, reaching from 

opposite the third pair of glabellar furrows back nearly to the 

posterior margin, conforming in direction to the eye of Paradoxides rugulosus.

Thorax with nine segments; axial lobe convex, broad, and 

tapering very gradually towards the pygidium; a furrow crosses 

obliquely from each posterior side of the segment and almost 

unites before the base of a short spine that originates at the 

center of each segment and extends upward and backward. 

The spine on the eighth segment is prolonged and extends back 

quite a distance beyond the extremity of the terminal spines of 

the pygidium. An individual 15mm long shows the spine with a 

length of 10mm . The body of the pleural lobes is narrow, and 

each pleura is extended in a long spine; pleural groove short and 

nearly as broad as in the genus Olenellus.

Pygidium subquadrangular; median lobe obconical, convex, 

divided into three segments and a terminal portion; lateral lobes 

formed of three segments directed backward, terminating in 

sharp points and gradually decreasing in size backward.

Discussion.—Z. typicalis (Walcott) is characterized 

by a cranidial border slightly narrower than the 

brim, by the anterior branch of the facial suture which 

nearly touches the dorsal furrow immediately in front 

of the palpebral lobe, by the relatively broad axial lobe 

of the thorax and pygidium, and by having three pairs 

of marginal spines decreasing in length posteriorly on 

the pygidium.

The hypostome described for this species probably 

belongs to Alokistocare piochensis (Walcott), an associated ptychopariid trilobite. It la'cks the strong
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 71

"anterior wings" cited by Rasetti (1952, p. 890) for 

corynexochid trilobites.

Occurrence.—Middle Cambrian, Chisholm shale, Pioche, Nev.

Figured specimen.—Holotype, nearly complete carapace, USNM 15454, length, 33 millimeters.

Superfamily PTYCHOPARIOIDEA Richter

Rasetti (1951, p. 198) gives an excellent discussion of 

the problems facing a paleontologist dealing with trilobites of this superfamily. The genera discussed here 

are arranged alphabetically.

Genus ALOKISTOCARE Lorenz, 1906

Alokistocare Lorenz, 1906, Deutsche Geol. Gesell. Zeitschr., 

Band 58, p. 62.

Walcott, 1916, Smithsonian Misc. Coll., v. 64 no. 5, p. 182.

Resser, 1935, idem, v. 93, no. 5, p. 4.

Rasetti, 1951, idem, v. 116, no. 5, p. 202. 

Amecephalus Walcott, 1924, idem, v. 75, no. 2, p. 53.

Walcott, 1925, idem, no, 3, p. 65.

Genotype.—Conocephalites subcoronatus Hall and 

Whitfield, 1877 (p. 237, pi. 2, fig. 1).

Diagnosis.—Micropygous ptychoparioidea. Frontal 

area long. Brim and border present but poorly differentiated. Median swelling extends from brim onto 

border. Width of fixed cheeks greater than one-half 

width of glabella. Thorax of 17 to 23 segments.

Description.—Cephalon subsemicircular in outline; 

posterior margin straight; distinct genal spines extend 

posteriorly from posterolateral corners.

Cranidium subquadrate in outline, gently to moderately rounded anteriorly. Glabella well defined by 

dorsal furrow, tapered forward, bluntly rounded or 

truncate anteriorly; 3 or 4 pairs of shallow glabellar 

furrows usually visible. Occipital furrow deep at 

sides of glabella, shallow across midline. Occipital 

ring flat. Frontal area long, broad; border flat or 

gently arched upward or downward; axial length variable. A low, poorly defined median swelling extends 

from brim onto border. Fixed cheeks, gently to 

moderately arched; width usually more than half that 

of glabella; ocular ridges extend from palpebral lobes 

to dorsal furrow just behind anterior end of glabella. 

Posterior limbs as long or longer than occipital ring.

Facial sutures divergent forward from palpebral lobes 

until nearly across border, then turned abruptly inward to cut anterior margin about midway between 

anterolateral corner of cranidium and longitudinal 

axis. Posterior suture cuts margin well within genal 

angle.

Free cheek with evenly curved lateral margin. 

Border concave, narrower than ocular platform.

Thorax of 17 to 23 segments in known articulated 

specimens. Axial lobe narrower than pleural lobes,

well defined by dorsal furrows. Pleural lobes of each 

segment with distinct pleural furrows and rounded or 

pointed distal extremities.

Pygidium with prominent axial lobe reaching nearly 

to posterior margin; pleural lobes triangular in outline, 

about as wide as axial lobe at anterior margin. Border 

concave, poorly defined, narrows posteriorly. Furrows 

on axial and pleural lobes shallow.

Surface of carapace smooth, granular or pitted.

Discussion.—Lorenz (1906, p. 62) proposed this genus 

with C. subcoronatus as type without giving a diagnosis. 

The first diagnosis was by Walcott (1916, p. 182). 

Resser (1935, p. 4) redefined the genus to exclude some 

of the species placed in it by Walcott. He also concluded that Amecephalus Walcott (1924, p. 53) was a 

synonym of Alokistocare. Rasetti (1951, p. 202) discussed Alokistocare and considered Amecephalus as a 

recognizable genus. The writer considers the evidence 

given below to be sufficient for placing Amecephalus 

Walcott, 1924, in the synonymy with Alokistocare 

Lorenz, 1906.

The genotype of Alokistocare is represented only by 

cranidia preserved in dark limestone. The genotype 

of Amecephalus is represented by flattened complete 

and disarticulated specimens in a soft, brown shale. 

Four species of Alokistocare were described by Resser 

(1938) from complete trilobite shields in the Spence 

shale of Idaho. Comparison of the cranidia with those 

assigned to A. subcoronatum (Hall and Whitfield) 

indicates that the generic determination for the specimens described by Resser is probably correct. Furthermore, the specimens from Idaho and A< subcoronatum 

(Hall and Whitfield) from northern Utah come from 

about the same stratigraphic horizon. Rasetti (1951, 

p. 202) states "If forms known from complete shields 

and described by Resser as Alokistocare belong to the 

genus, they appear to differ from Amecephalus piochensis in possessing somewhat narrower fixed cheeks 

and in the different form of the thoracic pleura, which 

extend into falcate terminations in Amecephalus 

piochensis, while they remain almost straight in the 

forms assigned to Alokistocare." He considers these 

differences of generic importance.

The writer has examined the complete shields mentioned by Rasetti and assigned to four species of 

Alokistocare by Resser. Two of the species, A. idahoense Resser and A. spencense Resser, have falcate 

thoracic terminations similar to those of Amecephalus 

piochensis (Walcott). The other two species, A. 

laticeps Resser and A. septum Resser, have rounded 

thoracic terminations with one exception—a specimen 

of A. septum Resser with the large long, genal spines 

and granular surface characteristic of that species 

but with falcate thoracic terminations. It seems un-
72 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

likely, then, that the character of the thoracic terminations is of generic importance in the AlokistocareAmecephalus group of trilobites.

The width of the fixed cheeks, including the palpebral lobes, divided by the width of the glabella on the 

same transverse line gives figures of: 1.19, 1.15 and 1.15 

for 3 limestone specimens selected at random from a 

collection of Alokistocare subcoronatum (Hall and Whitfield); 1.00, 1.13 and 1.15 for 3 slightly crushed shale 

specimens selected at random from a collection of 

Alokistocare idahoense Resser; and 1.00, 1.19 and 1.18 

for 3 flattened shale specimens selected at random from 

a collection of Amecephalus piochensis (Walcott). 

These ratios suggest that differences in the relative 

width of the fixed cheeks of these trilobites, like the 

differences in thoracic terminations, are not valid criteria for generic differentiation.

Alokistocare piochensis (Walcott) 

Plate 16, figures 1, 2, 5

Ptychoparia piochensis Walcott, 1886, U. S. Geol. Survey Bull.

30, p. 201, pi. 26, fig. 2b; pi. 28, figs. 1, la-e. 

Pack, 1906, Jour. Geol. v. 14, no. 4, p. 297, pi. 2, fig. 4a. 

Amecephalus piochensis (Walcott), 1924, Smithsonian Misc.

Coll., v. 75, no. 2, p. 53, pi. 9, fig. 1. 

Walcott, 1925, idem, no. 3, p. 66, pi. 15, figs. 8-10. 

Alokistocare packi Resser, 1935, idem, v. 93, no. 5, p. 9.

Description.—Walcott (1886, p. 201) gives a detailed 

description of this species as follows:

General form ovate, moderately convex, usually much depressed by being flattened in^the shaly matrix.

Head transverse, semicircular; frontal margin comparatively 

narrow in young individuals, becoming broader and more flattened with the increase in size of the animal; postero-lateral 

angles prolonged into slender spines. Glabella of medium size, 

truncatoconical, and marked with three pairs of short glabellar 

furrows that increase in size and also in obliquity to the central 

axis on the larger heads; occipital groove shallow and rounded 

downward from the base of the glabella and upward to the moderately strong occipital ring; a small point or node occurs at the 

center of the latter. Fixed cheeks of medium width; they 

merge in front into the broad frontal limb and posteriorly into 

the elongate, narrow, postero-lateral limbs; palpebral lobes small; 

ocular ridges well defined and terminating nearly at the front of 

the glabella; frontal limb comparatively narrow in the young 

and broader in the older and larger specimens.

Thorax with 19 segments in two specimens 30mm and 40mm 

long, respectively; another specimen, 18mm long, shows 17 segments; the segments are nearly transverse, except at the geniculation on the pleural lobes, where the falcate extremities bend 

slightly backward; axial lobe moderately convex; pleural lobes 

flattened half-way out and then curved downward to their 

margin; pleural groove of medium width and continued well out 

towards the extremity of the segment.

Pygidium small, semicircular; axial lobe with 3 or 4 segments; 

lateral lobes small and marked by furrows indicating about 3 

united segments.

Discussion.—A. piochensis (Walcott) is characterized by having the midlength of the border of the

cranidium less than the midlength of the brim, 17 to 

19 thoracic segments, and a small pygidium.

Resser (1935, p. 9) placed two specimens figured by 

Walcott (1886, pi. 28, figs. Ic, Id) as Ptychoparia 

piochensis in a new species, Alokistocare packi with the 

following comment: "In the narrowness of the cranidium this species is like A. pomona." This is hardly 

an adequate specific diagnosis. The specimens, both 

small, are associated with Alokistocare piochensis 

(Walcott). Walcott's interpretation of them as small 

individuals of that species is more probably correct.

Occurrence.—Middle Cambrian, Chisholm shale, 

Pioche, Nev.

Figured specimens.—Holotype cranidium, USNM 

15434, length, 25 millimeters; nearly complete carapace, 

USNM 15434, length, 28 millimeters; small, nearly 

complete carapace, USNM 15434, length, 17 millimeters.

Alokistocare subcoronatum (Hall and Whitfleld) 

Plate 15, figure 8

Concephalites subcoronatus Hall and Whitfield, 1877, U. S.

Geol. Expl. 40th Par. Rept., v. 4, p. 237, pi. 2, fig. 1. 

Ftychoparia subcoronata (Hall and Whitfield), Walcott, 1886,

U. S. Geol. Survey Bull. 30, p. 205, pi. 28, fig. 4. 

Walcott, 1890, U. S. Geol. Survey 10th Ann. Rept., pt. 1,

p. 652, pi. 96, fig. 6. 

Alokistocare subcoronatum (Hall and Whitfield), Walcott, 1916,

Smithsonian Misc. Coll., v. 64, no. 5, p. 187, pi. 25, fig. 2.

Description.—This species was described in considerable detail by Hall and Whitfield (1877, p. 237).

Glabella short, conical, with straight lateral margins, regularly 

converging from the base upward to the rather squarely truncated summit; height above the occipital furrow scarcely exceeding the breadth of the base, and the width at the summit equal 

to about two-thirds of the height; marked by three pairs of very 

oblique, subequally distant, and moderately distinct transverse 

furrows. Occipital furrow narrow and well marked; ring distinct, widest and somewhat pointed on the center of the posterior 

margin.

Fixed cheeks wide, separated from the glabella by distinct 

dorsal furrows, prominent and rounded between the glabella and 

eye-lobe, almost equaling the convexity of the glabella; ocular 

ridges slender and curved. Frontal limb wide and concave, 

destitute of a thickened marginal rim, as long as the glabella, 

and obscurely trilobed from an extension of the dorsal furrows, 

forming a convex, boss-like area in front of the glabella, which 

is divided transversely by a double depressed line, or narrow 

fillet, midway of the limb and parallel with the anterior margin 

of the head. Eye-lobes about half as long as the glabella, 

obliquely situated, and separated from the fixed cheek by a 

deeply-depressed ocular sinus.

Facial suture cutting the anterior border on a line with the 

front angle of the eye, which it reaches by a broad, convex 

curvature, giving rounded lateral margins to the frontal limb; 

posterior to the eye, it is directed outward; the actual course 

not determined. Posterior lateral limbs not seen. Surface of 

the crust in front of the glabella strongly striated.

Discussion.—Although there is no "thickened marginal rim" on the cranidium as -noted by Hall and
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 73

Whitfield, there is a concave border nearly twice the 

length of the brim. It is defined by a shallow marginal 

furrow that parallels the eye lines and the front of the 

glabella and crosses the low faint median boss. The 

character of the marginal furrow, relative proportions 

of the brim to border, low median boss, distinct occipital 

furrow, and relatively small size are characteristic of 

the species.

Occurrence.—Middle Cambrian, Ute limestone, Bear 

River Range, Utah.

Figured specimen.—Holotype cranidium, USNM 

15442, length, 5 millimeters.

Genus ASAPHISCUS Meek, 1873

Asaphiscus Meek, 1873, U. S. Geol. Survey Terr. 6th Ann. Rept., 

p. 485.

Walcott, 1886, U. S. Geol. Survey Bull. 30, p. 219.

Resser, 1935, Smithsonian Misc. Coll., v. 93, no. 5, p. 12. 

Eteraspis Resser, 1935, idem, p. 28.

Genotype.—Asaphiscus wheeleri Meek, 1873 (p. 485).

Diagnosis.—Cephalon subsemicircular in outline, 

posterior margin nearly straight, genal angles rounded.

Cranidium with glabella tapered forward, strongly 

rounded anteriorly, poorly defined by shallow dorsal 

furrow. Glabellar furrows not visible. Occipital furrow shallow. Occipital ring gently rounded. Frontal 

area with deep, curved marginal furrow. Border gently 

arched upward, width constant. Fixed cheeks downsloping from glabella; palpebral lobes not defined by 

palpebral furrow, situated opposite middle third of 

glabella. Length of posterior limbs about equal to 

width of glabella at occipital furrow; marginal furrow 

broad, shallow. Facial sutures divergent anterior and 

posterior to palpebral lobes. Anterior course extended 

onto border and then turned abruptly inward to cut 

anterior margin intermediate between anterolateral corners of cranidium and longitudinal axis. Posterior 

course extended backward and outward in even curve 

to cut margin within genal angle.

Free cheek with evenly rounded lateral margin. 

Marginal furrow moderately deep, parallels margin. 

Genal angle rounded.

Thorax consists of nine segments. Axial lobe prominent, narrower than pleural lobes. Pleural lobes of 

each segment subequally divided by deep pleural furrows near axial lobe, flattened and rounded distally.

Pygidium about as large as cephalon, subsemicircular 

in outline, width less than twice length. Axial lobe 

prominent, tapered posteriorly, extended to or onto 

border. Border of nearly constant width, narrower 

than widest portion of pleural platform. Axial and 

pleural furrows shallow.

Discussion.—The deep marginal furrow, shallow 

dorsal furrow, and rounded genal angles of the cephalon 

of this genus are its most distinctive characteristics.

Walcott (1916, p. 383) expanded the genus to include 

13 species from Middle and Upper Cambrian rocks of 

North America and Asia. Resser (1935, p. 12) restricted it to A. wheeleri Meek and A. iddingsi Walcott, 

and all other species assigned to the genus up to that 

time were placed elsewhere. Resser and Endo (1937, 

p. 180-183) described 6 new Asiatic species of Asaphiscus similar to A. iddingsi Walcott. The Asiatic trilobites differ from the genotype by their well defined 

glabellas, relatively longer palpebral lobes, and genal 

spines. The writer does not consider them to belong 

to the genus.

Resser (1935, p. 28) proposed the genus Eteraspis 

with Ptychoparia laeviceps Walcott as genotype. Although the free cheeks of P. laeviceps Walcott are not 

known, the writer considers the species congeneric with 

Asaphicus wheeleri Meek. (See discussion of A. laeviceps (Walcott).) Eteraspis Resser, 1935, becomes 

therefore a synonym of Asaphiscus Meek, 1873.

Asaphiscus laeviceps (Walcott) 

Plate 16, figures 4, 6

Ptychoparia laeviceps Walcott, 1884, U. S. Geol. Survey Mon 8,

p. 54, pi. 10, fig. 17. 

Eteraspis laeviceps (Walcott), Resser, 1935, Smithsonian Misc.

Coll., v. 93, no. 5, p. 28. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 611, pi. 255, fig. 20.

Description.—Walcott (1884, p. 54) presented a detailed description of the cranidium of this species.

General form of head within the-facial sutures subtrapezoidal, 

Glabella conical, strongly convex, with very faintly defined 

dorsal furrows separating it from the rapidly sloping fixed chseks; 

two pairs of furrows are just discernible by slight impressions on 

the surface; occipital ring strong, rounded, separated from the 

glabella by a shallow furrow; fixed cheeks of medium width, sloping rapidly down from the glabella and from the small eyelobe, 

situated a little back of the center, to the front and back; frontal 

limb short, convex, and depressed to the broadly rounded, strong, 

marginal rim; postero-lateral limbs rather strong and running 

out beyond the line of the lateral extension of the frontal limb.

Pygidium subsemicircular in outline; width slightly 

less than twice length. Axial lobe elongate, distinctly 

elevated above pleural platforms, tapering posteriorly, 

merging with border. Border faintly defined by marginal furrow, maintaining nearly constant width. Axis 

and pleural lobes marked by several extremely faint 

furrows.

Discussion.—Ptychoparia laeviceps Walcott was madethe type of Eteraspis by Resser (1935, p. 28). He diet 

not compare the genus to any already described. Examination of the specimens of P. laeviceps Walcott and 

Asaphiscus wheeleri Meek suggests that they represent 

two species of a single genus. The cranidia are nearly 

identical. The pygidium of P. laeviceps Walcott differs 

from that of A. wheeleri Meek by having the axial lobe
74 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

extended onto and merged with the border and the 

border convex instead of concave. The writer does not 

feel that the differences between the species are of 

generic importance and considers Eteraspis Resser a 

synonym of Asaphiscus Meek.

A. laeviceps (Walcott) is younger than A. wheeleri 

Meek and occurs at or near the top of the Middle 

Cambrian.

Occurrence.—Middle Cambrian, Hamburg limestone 

(lower part), Eureka, Nev.

Figured specimens.—Holotype cranidium, USNM 

24614, length, 7.5 millimeters; pygidium, USNM 24614, 

length 5 millimeters.

Asaphiscus wheeled Meek 

Plate 16, figure 7

Asaphiscus wheeleri Meek, 1873, U. S. Geol. Survey Terr. 6th

Ann. Kept., p. 485. 

White, 1877, U. S. Geog. Surveys W. 100th Mer., v. 4,

p. 43, pi. 2, figs. la-f. 

Walcott, 1886, U. S. Geol. Survey Bull. 30, p. 220, pi. 25,

fig. 9; pi. 31, figs. 3, 3a. 

Walcott, 1916, Smithsonian Misc. Coll., v. 64, no. 5, p. 390,

pi. 58, figs. la-g. 

Shimer and Shrock, 1944, Index Fossils of North America, p.

607, pi. 258, fig. 9.

Description.—White (1877, p. 43) presented a detailed description of this species.

Body oblong-ovate in outline; surface smooth. Head depressed convex; front margin regularly rounded; posterolateral angles abruptly rounded, without cheek spines; 

exterior margin bent shortly upward all around, producing a 

raised border of considerable width, and also a rather deep 

linear depression, or groove, parallel with that border and 

between it and the remainder of the cheeks. Glabella conical, 

much wider behind than in front, depressed; space between its 

anterior end and the marginal groove about equal to the width 

of the raised marginal rim in front of it; outline well defined 

by the narrow dorsal furrows; sides nearly straight; anterior 

end abruptly and posterior end broadly rounded, without lateral 

furrows, or at least they are hardly discernible; occipital furrow 

shallow, broad, but somewhat distinct and uniform, extending 

entirely across the glabella, and continuous with furrows similar 

to itself that extend to the posterolateral angles of the head; 

the latter furrows lie parallel with and near to the posterior 

margin of the head, giving that margin also a raised border, 

somewhat like the one upon the exterior margin. Eyes comparatively small, crescentic, situated nearly opposite the midlength of the glabella, and nearly equidistant from it and the 

posterior margin.

Thorax having nine segments; its length not quite so great as 

that of the head; axis broadest anteriorly, more strongly convex, 

and about one-third narrower than the lateral lobes are; segments extending straight across the lobe; lateral lobes depressed, 

their greatest convexity along the middle; pleurae bluntly 

pointed at their outer ends, the points not being directed very 

strongly backward; their inner ends so joined to the axial segments that they have the appearance of lapping a little upon 

them just inside the dorsal furrow; grooved, the groove being 

deepest about mid-length, where the outer and inner portions

of its front border meet at a distinct but very obtuse angle; 

grooves extending from the dorsal furrow nearly to the extremity 

of the pleurae, where they disappear.

Pygidium somewhat semicircular in outline, distinct trilobate; 

segmentation indistinct, so much so in some of the specimens that 

the surface appears nearly as plain as that of an Asaphus, 

but the segmentation is usually more distinctly shown upon 

surfaces from which the crust has been removed; axis prominent, 

especially at its distal end, where it terminates abruptly at the 

inner edge of the broad marginal border; segments of axial 

lobe eight or ten; lateral lobes much depressed, a little wider 

than the axial lobe at the anterior end, and narrowing to an 

incurved point at the end of the axis; the whole exterior margin 

having a broad, flat border of nearly uniform width throughout; 

the under surface of this border marked by fine, somewhat 

irregular, longitudinal striae, such as are usually seen upon 

corresponding parts of Asaphus.

The largest specimen in the collection is about seven 

centimeters long.

Discussion.—This species is characterized by the subequal axial lengths of the brim and border on the 

cranidium and by the axial lobe of the pygidium, which 

reaches to, but not onto, the border.

The types of this species are all fragmentary. The 

specimen pictured here, although slightly crushed, is 

the best specimen in the U. S. National Museum, collections and is from topotype material. It exhibits all of 

the distinctive characters of the species. A. laeviceps 

(Walcott) (pi. 16, fig. 4) from the Eureka district, Nev. 

shows the natural convexity of cranidia of this genus.

Occurrence.—Middle Cambrian, Wheeler formation, 

House Range, Utah.

Figured specimen. — Complete carapace, USNM 

15460, length, 28 millimeters.

Genus BOLASPIDELLA Resser, 1937

Bolaspidella Resser, 1937, Smithsonian Misc. Coll., v. 95, no.

22, p. 3.

Shaw, 1952, Jour. Paleontology v. 26, no. 3, p. 477. 

Palmer, 1954, [in press] Jour. Paleontology. 

Hysteropleura Raymond, 1937, Geol. Soc. America Bull., v. 48,

no. 8, p. 1094. 

Deltophthalamus Resser, 1938a, Geol. Soc. America Special Paper

15, p. 74. 

Deissella Howell and Duncan, 1939, Wagner Free Inst. Sci. Bull.,

v. 14, no. 1, p. 7. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 609.

Howellaspis Lochman and Denson, 1944, in Lochman and Duncan, 1944, Geol. Soc. America Special Paper 54, p. 125.

Genotype.—Ptychoparia housensis Walcott, 1886 (p. 

201, pi. 25, fig. 5).

Diagnosis.—Small micropygous trilobites. Cranidium with prominent subquadrate glabella; glabellar 

furrows represented by pits on sides of glabella. Occipital furrow deep. Occipital ring with or without spine. 

Frontal area concave. Brim and border distinct; border usually upturned. Width of fixed cheeks greater 

than one-half width of glabella; palpebral lobes small,
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900

opposite or anterior to middle third of glabella. Ocular 

ridges usually present. Facial sutures directed straight 

forward in front of palpebral lobes; widely divergent 

behind.

Free cheek transversely elongate with evenly rounded 

margin, short genal spine.

Thorax consists of 15 segments. Axial lobe narrower 

than pleural lobes. Distal extremities of each segment 

sharply rounded.

Pygidium with prominent conical axial lobe reaching 

nearly to posterior margin. Axial and pleural lobes 

with 2 or 3 shallow furrows.

Discussion.—This genus is common in rocks of 

late Middle Cambrian and earliest Late Cambrian age. 

It has been found in the Cordilleran and Appalachian 

regions and central Texas. The prominent subquadrate 

glabella, concave frontal area, and wide fixed cheeks are 

particularly characteristic of the cranidium. A complete 

specimen collected by the writer from the Wheeler formation at the Elrathia kingii type locality, and the 

genotype of Deltophthalamus Resser, provided information about the free cheeks, thorax and pygidium. Disassociated free cheeks and a pygidium have been described from central Texas (Palmer, 1954, in press).

Hysteropleura, Deissella and Howellaspis were considered synonyms of Bolaspidella by Shaw (1952, p. 

477). Deltophthalamus has been considered a synonym 

of Bolaspidella by the writer (Palmer, 1954, in press).

Bolaspidella housensis (Walcott)

Plate 16, figure 3

Ptychoparia housensis Walcott, 1886, U. S. Geol. Survey Bull. 

30, p. 201, pi. 25, fig 5.

Description.—The cranidium and only known part 

of this species was described by Walcott (1886, p. 201).

Head small, transversely quadrilateral exclusive of the free 

cheeks; moderately convex. Glabella rather small, of almost 

uniform width from the posterior margin to the rounded front; 

furrows shown only by a posterior pair; occipital ring strong 

and bearing a short small spine that extends obliquely upward 

and backward; occipital furrow of moderate depth and continued out as a strong groove on the lateral limbs; dorsal furrows 

broad and well defined. Fixed cheeks wider than the glabella; 

palpebral lobes small; ocular ridges strongly defined; frontal limb 

concave, of medium width, and rising to a strong frontal rim; 

postero-lateral limbs short. Surface finely granulose.

Discussion.—P. housensis (Walcott) differs from all 

other species of Bolaspidella by possessing an occipital 

spine.

Occurrence.—Middle Cambrian, Wheeler formation, 

House Range, Utah.

Figured specimen.—Holotype cranidium, USNM 

24614, length 4 millimeters.

Genus EHMANIELLA Resser, 1937

Ehmaniella Resser, 1937, Smithsonian Misc. Coll., v. 95, no. 22, 

p. 10.

Genotype.—Crepicephalus (Loganellus) guadrans Hall 

and Whitfield, 1877 (p. 238, pi. 2, figs. 11-13).

Diagnosis.—Cranidium with anterior margin gently 

and evenly rounded, glabella prominent, tapered forward, bluntly rounded anteriorly; dorsal furrow deep 

at sides, shallow across front. Four pairs of glabellar 

furrows visible on well-preserved specimens. Occipital 

furrow deep at sides, shallow on midline. Occipital 

ring with or without spine. Frontal area with distinct 

brim and border separated by shallow marginal furrow 

or by sudden change in slope; border maintains constant width; axial length of frontal area less than half 

that of glabella. Width of fixed cheeks about one-half 

that of glabella. Prominent ocular ridges present. 

These touch dorsal furrow opposite anterior pair of 

glabellar furrows. Palpebral lobes poorly defined by 

shallow palpebral furrow, depressed below general level 

of cheeks, opposite middle third of glabella. Length of 

posterior limbs about equal to width of glabella at 

occipital furrow. Anterior and posterior courses of 

facial sutures divergent from palpebral lobes; anterior 

course intramarginal on border nearly to axial line.

Free cheek with margin evenly rounded. Border 

narrower than ocular platform, well defined by shallow 

marginal furrow, extended into short, pointed genal 

spine.

Thorax of 13 segments. Axial lobe prominent, 

narrower than pleural lobes. Distal ends of pleural 

lobes of each segment rounded or extended into short 

sharp spines.

Pygidium with axial length one-half or more width. 

Axial lobe tapered posteriorly, not extended to posterior 

margin, composed of 3 to 5 segments. Pleural lobes 

with 2 or more pairs of pleural furrows and interpleural 

grooves of about equal strength; each pair of furrows 

directed more posteriorly than preceding pair. Border 

not present, but distal margins of downsloping pleural 

lobes flexed outward.

Surface of carapace smooth.

Discussion.—The choice of genotype for this genus 

was unfortunate. The types of E. guadrans (Hall and 

Whitfield) are flattened and the diagnostic generic 

characteristics are distorted or poorly preserved. 

Specimens from USGS locality 20x (OS), limestones in 

the Spence shale from near the type area, are undisdistorted and show the generic characteristics. The 

character of the thorax was taken from specimens 

described by Rasetti (1951, p. 218, 219) from the 

Stephen formation in British Columbia.

The genus differs from Ehmania Resser only in 

characters of tha cranidium. The ocular ridges ar8
76 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

more prominent; the axial length of the border is less 

than that of the brim, and the border is not tapered 

distally. The cranidium differs from those of other 

similar genera by having an anteriorly tapered glabella, 

a shallow or indistinct marginal furrow, anteriorly 

divergent facial sutures, and the palpebral lobes opposite 

the middle third of the glabella. The greater relative 

leogth, more distinctly furrowed pleura! lobes and l.ack 

of a well-defined border distinguish the pygidium. from 

those of similar genera.

Ehmaniella quadrans (Hall and Whit field) 

Plate 17, figures 1-5

Crepicephalus? (Loganellus) quadrans Hall and Whitfield, 1877,

U. S. Geol. Expl. 40th Par. Rept. v. 4, p. 238, pi. 2,

figs. 11-13. 

Ptychoparia quadrans (Hall and Whitfield), Walcott, 1886, U. S.

Geol. Survey Bull. 30, p. 199, pi. 29, figs. 4, 4a, b. 

Ehmaniella quadrans (Hall and Whitfield), Resser, 1939, Smithsonian Misc. Coll., v. 97, no. 12, p. 19, pi. 6, figs. 28-32.

Description.—This species was described in detail 

by Hall and Whitfield (1877, p. 238).

Form of entire body unknown. Glabella and fixed cheeks 

together broadly quadrangular, about four-fifths as high as wide 

and quite uniform in many individuals, very depressed-convex 

or quite flattened, as occurring on the surface of the shale in 

which they are imbedded; glabella distinctly conical, moderately 

tapering above the occipital furrow, and broadly rounded in 

front; marked by three pairs of distinct transverse furrows, which 

are directed obliquely backward from their outer ends; the 

posterior pair almost or quite meeting in the middle, the others 

shorter and situated at almost equal distances from each other. 

Occipital furrow well marked, proportionally wide and shallow; 

occipital ring narrow, not well defined.

Fixed cheeks very broad, nearly two-thirds as wide as the 

glabella, depressed-convex; frontal limb short, the broader and 

inner part of nearly the same width; sides of the limb in front, 

wide, and slightly rounded at the antero-lateral angles; posterior 

limb wide at its junction with the glabella, and rapidly narrowing 

outward, being about once and a half as long as its greatest 

width; ocular ridges slender, but very distinct, rising from the 

anterior angle of the eye and uniting with the glabella near the 

anterior furrow, forming a slightly curved line parallel with the 

marginal furrow of the head.

Facial sutures directed inward from the anterior margin of the 

head to the eye-lobe, behind which they are directed outward and 

backward to the posterior margin of the head, at an angle of 

about forty degrees to the occipital line.

A form of movable cheek found associated in considerable 

numbers with the glabellas, and corresponding in size and character, is narrowly triangular, the posterior extremity terminating 

in a short, blunt spine, slightly curved; inner angle strongly 

notched for the reception of the eye-lobe, and the outer margin 

bordered by a thickened, rounded rim, which gradually increases 

In width to the base of the spine. The facial suture corresponds 

to the margin of the fixed cheek above described, and, on the 

under side, the anterior border is prolonged in the form of an 

acute process, to extend along the anterior border of the frontal 

limb.

The pygidium associated with the above specimens is minute, 

transversely subelliptical in form, most strongly rounded on the

front border, with a wide axis terminating obtusely a little within 

the posterior margin. The axis is marked by five rings, exclusive 

of the terminal ones. Lateral lobes convex, marked by three or 

four divided ribs, exclusive of the anterior single one. 

. Surface of the head and cheeks marked by fine anastomosing 

lines, radiating from the eye and front of the glabella.

Discussion.—This species is similar to Ehmania 

weedi Resser, the genotype of Ehmania. The cranidium 

has a shorter border that is not tapered distally and 

more prominent ocular ridges. The pygidium has 

each successive pair of pleural furrows and interpleural grooves more strongly curved posteriorly. 

On the pygidium of Ehmania, the furrows and grooves 

maintain a nearly constant angle with the axial line.

Occurrence.—Middle Cambrian, Spence shale member 

of the Ute limestone, Wasatch Range, Utah.

Figured specimens.—Holotype cranidium, USNM 

15432, length, 5.5 millimeters; pygidium, USNM 

15432, length, 3.5 millimeters; crandium, USNM 

12335la, length, 6 millimeters; pygidium USNM 

123351b, length, 4 millimeters; free cheek, USNM 

15432, width 3.5 millimeters.

Genus ELDORADIA Resser, 1935

Eldoradia Resser, 1935, Smithsonian Misc. Coll., v. 93, no. 5, 

p. 26.

Genotype.—Ptychoparia? linnarssoni Walcott, 1884 

(p. 47, pi. 9, figs. 18, 18a).

Diagnosis.—Cranidium subquadrate in outline; glabella prominent, relatively small, tapered forward, 

truncate anteriorly. Glabellar furrows shallow or absent. Occipital furrow shallow. Frontal area nearly as 

long as glabella; border not distinctly differentiated 

from brim; brim with large median boss extending from 

front of glabella to border. Fixed cheeks as wide or 

wider than glabella. Palpebral lobes small, opposite 

anterior third of glabella; palpebral furrow absent. 

Facial sutures straight forward in front of palpebral 

lobes, widely divergent behind.

Free cheek, thorax, and pygidium unknown.

Discussion.—This genus is distinguished from Alokistocare by the confinement of the preglabellar median 

boss to the brim and the continuatioa of the shallow 

marginal furrow around the front of the boss instead 

of over it.

The writer has seen specimens of Eldoradia from 

an undetermined formation in the House Range in 

Utah and from the Abrigo limestone in the Tombstone 

and Bisbee mining districts in southeastern Arizona, in 

addition to those from the Eureka mining district in 

Nevada.

Eldoradia dunbari Lochman (1938, p. 465) from the 

March Point formation, Newfoundland, lacks a preglabellar median boss and has a short frontal area, distinct glabellar furrows, and the palpebral lobes are
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 77

situated opposite the middle third of the glabella. 

The writer does not consider it as a representative of 

Eldoradia.

Eldoradia linnarssoni (Walcott) 

Plate 16, figures 9, 10

Ptychopariaf linnarssoni Walcott, 1884, U. S. Geol. Survey Mon.

8, p. 47, pi. 9, figs. 18, 18a. 

Alokistocare linnarssoni (Walcott), Walcott, 1916, Smithsonian

Misc. Coll., v. 64, no. 5, p. 185, pi. 25, figs. 7, 7a. 

Eldoradia linnarssoni (Walcott), Resder, 1935, idem, v. 93, no.

5, p. 27. 

Eldoradia lata Resser, 1935, idem, p. 27.

Description.—Walcott (1889, p. 47) presented a detailed description of the cranidium of this species.

The glabella and fixed cheeks are the only portions of this 

interesting species that have been identified. The glabella is 

small in proportion to the area occupied by the cheeks and 

frontal limb; it is conical in form, truncate in front, moderately 

convex, and marked by three pairs of very short, slightly impressed glabellar furrows; the latter only observed on very perfect 

specimens; occipital ring narrow, as also the shallow occipital 

furrow; fixed cheeks broad, elevated, and projecting forward on 

to the frontal limb considerably in advance of the front of the 

glabella, the included space between their anterior portions being 

occupied by an elongate oval boss that is separated from the 

glabella by a rather broad, shallow furrow; the boss or tubercle 

extends to the rounded thick frontal rim, from which it is defined 

by a scarcely perceptible depression; dorsal furrows broad, well 

defined, and running out in front much broader between the 

tubercle and the fixed cheeks; palpebral lobes rather prominent 

and situated opposite the anterior end of the glabella; posterolateral limbs long, triangular, and marked by a strong furrow 

within their posterior margin. Facial suture directed forward 

in front of the eyelobes, curving outward a trifle and then a little 

inward on the frontal limb, around the front of which it does 

not appear to extend; back of the eyelobe it extends obliquely 

outward and backward, bending a little more abruptly backward 

towards the lateral extension of the limb, terminating at or just 

within the genal angle at a distance from the dorsal furrow equal 

in one example to the length, and in another to two-thirds of 

the length of the head.

Discussion.—E. linnarssoni (Walcott) is characterized by having a short border and the width of the 

cranidium between the palpebral lobes slightly greater 

than the length. Resser (1935, p. 27) proposed the 

name Eldoradia lata for one of the specimens of E. 

linnarssoni (Walcott) illustrated by Walcott (1884, 

1916). The type of E. lata Resser is a weathered 

cranidium lacking the border. The loss has accentuated the apparent width of the fixed cheeks, which are 

relatively no wider than those of E. linnarssoni (Walcott). The diagnostic specific characteristic of "wider 

fixed cheeks" seems to be an optical illusion. E. lata 

(Resser) is here considered a synonym of E. linnarssoni 

(Walcott).

Occurrence.—Middle Cambrian, Secret Canyon shale, 

Eureka, Nev.

Figured specimens.—Holotype cranidium, USNM 

24611, length, 8.5 millimeters; cranidium, USNM 

90669, length, 8.5 millimeters.

JEldoradia prospectensis (Walcott) 

Plate 16, figure 8

Ptychopariaf prospectensis Walcott, 1884, U. S. Geol. Survey

Mon. 8, p. 46, pi. 9, fig. 20. 

Alokistocare prospectense (Walcott), Walcott, 1916, Smithsonian

Misc. coll., v. 64, no. 5, p. 186, pi. 25, fig. 8.

Description.—This species was described in detail 

by Walcott (1884, p. 46).

The general outline of the head is moderately convex, semicircular, the width being about twice the length.

The glabella is subconical, truncate in front and marked by 

three pairs of short, slightly impressed glabellar furrows; occipital 

ring distinctly defined by a narrow, lightly impressed occipital 

furrow; fixed cheeks broad, of equal elevation with the glabella, 

and extending beyond it anteriorly, the space between them on 

the broad frontal limb being taken by a small swelling or boss 

that, but for the slight transverse dorsal furrow between it and 

the glabella, might be mistaken for a continuation of the latter; 

the eyelobes are comparatively large for a species of this character 

and occupy a prominent position on the outer margin of the 

cheeks, a distinct ocular ridge crossing the latter from the anterior 

margin of the eyes to the dorsal furrow on a line with the front 

of the glabella; the lateral limbs are narrow, rather short, and 

slope rapidly downward back of the eyelobes; frontal limb broad 

at the center, narrowing in front of the fixed cheeks and bordered 

anteriorly by a not very distinctly defined rounded margin. 

The facial suture curves a little inward in front of the eye and 

appears to terminate on the front line somewhat in advance of 

a line passing through the center of the tubercle in front of the 

glabella; behind the eye it extends obliquely outward and backward to the posterior margin of the head, outlining an elongate 

triangular postero-lateral limb.

Discussion.—A short border and a cranidium that is 

wider between the palpebral lobes than it is long characterize E. prospectensis. The species is smaller and 

relatively broader than E. linnarssoni (Walcott). 

Specimens intermediate in size between the types of the 

two species, however, are also intermediate in the 

"diagnostic" characters. It is possible that the two 

merely represent large and small members of the same 

species. It is also possible that this is an evolutionary 

difference having a certain amount of stratigraphic 

importance. The necessary detailed stratigraphic information that would support one or the other of these 

views is lacking. The writer prefers, therefore, to 

recognize E. prospectensis (Walcott) and E. linnarssoni 

(Walcott) as separate species in the absence of welldocumented information to the contrary.

Occurrence.—Middle Cambrian, Secret Canyon shale 

(?), Eureka, Nev.

Figured specimen.—Holotype cranidium, USNM 

15441, length, 4.5 millimeters.
78 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Genus ELBATHIA Walcott, 1924

Elrathia Walcott, 1924, Smithsonian Misc. Coll., v. 75, no. 2, 

p. 56.

Walcott, 1925, idem, no. 3, p. 86. 

Resser, 1935, idem, v. 93, no. 5, p. 27.

Howell, 1937, Geol. Soc. America Bull., v. 48, no. 8, p. 1184. 

Shimer and Shrock, 1944, Index Fossils of North America, 

p. 611.

Genotype.—Conocoryphe (Conocephalites) kingii Meek, 

1870 (p. 63).

Diagnosis.—Carapace elongate subovate in outline, 

widest at posterior margin of cephalon.

Cephalon subsemicircular in outline, genal angles 

extended into genal spines.

Cranidium with anterior margin gently and evenly 

rounded. Glabella well defined by shallow dorsal 

furrow, straight sided, tapered forward, strongly and 

evenly rounded anteriorly. Glabellar furrows shallow 

or absent. Occipital furrow deepest at sides, shallow 

on midline. Occipital ring flat or gently arched, unspined. Frontal area with distinct brim and border; 

border flat or gently arched upward; marginal furrow 

shallow. Width of fixed cheeks one-half or more width 

of glabella. Paipebral lobes opposite middle third of 

glabella, well defined by shallow palpebral furrow. 

Ocular ridges indistinct. Length of posterior limbs 

about equal to width of glabella at occipital furrow. 

Marginal furrow broad, shallow. Facial sutures divergent anterior and posterior to paipebral lobs; anterior 

course turns inward after reaching border and cuts 

margin about midway between anterolateral corners of 

cranidium and axial line; posterior course cuts margin 

before reaching genal spine.

Free cheek with evenly curved lateral margin. 

Border well defined by shallow marginal furrow; extended into short genal spine.

Thorax of 13 segments. Axial lobe prominent; width 

less than half that of pleural lobes. Pleural lobe of 

each segment subequally divided by deep pleural furrow; distal extremity extended into short, sharp point.

Pygidium subsemicircular in outline, smaller than 

cephalon; axial length less than one-half width. Axial 

lobe prominent, not reaching posterior margin; width 

about one-half that of pleural lobes. Narrow border 

present, poorly defined by shallow marginal furrow. 

Furrows on axial and pleural lobes shallow.

Surface of carapace smooth.

Discussion.—The cranidium of this genus can be 

distinguished from cranidia of similar genera by the 

unfurrowed, straight-sided glabella with the strongly 

and evenly rounded anterior end and by the lack of 

distinct ocular ridges. It may reach a length of 15 

millimeters or more. The pygidium is distinguished 

by its subsemicircular outline, narrow a,xial lobe, shallow axial and pleural furrows, and by the presence of a 

distinct border.

Elrathia kingii (Meek) 

Plate 17, figure 13

Conocoryphe (Conocephalites) kingii Meek, 1870, Acad. Nat. Sci.

Philadelphia Proc., p. 63. 

Conocoryphe (Ptychoparia) kingii (Meek). Meek, 1877, U. S.

Geol. Expl. 40th Par. Kept., v. 4, p. 20, pi. 1, fig. 4. 

White, 1877, U. S. Geog. and Geol. Surveys W. 100th Mer.,

v. 4, pt. 1, p. 40, pi. 2, figs. 2a-c. 

Ptychoparia kingii (Meek). Walcott, 1886, U. S. Geol. Survey

Bull. 30, p. 193, pi. 27, figs. 4, 4a. 

Walcott, 1913, Carnegie Inst. Washington Pub. 54, v. 3, pi.

12, fig. 6. 

Elrathia kingii (Meek). Walcott, 1924, Smithsonian Misc. Coll.,

v. 75, no. 2, p. 56, pi. 11, fig. 4. 

Walcott, 1925, idem, no. 3, p. 87, pi. 15, figs. 1-4. 

Shimer and Shrock, 1944, Index Fossils of North America, 

p. 611, pi. 255, figs. 5, 6.

Description.—Meek (1870, p. 63) described this species in considerable detail.

Entire form ovate and much depressed, with breadth equaling about two-thirds the whole length. Cephalic shield semicircular, or a little wider than long, with the anterior and 

antero-lateral borders regularly rounded in outline and provided with a narrow, slightly defined marginal rim; posterior 

margin nearly straight, with the lateral angles terminating in 

abruptly pointed extremities, so short as scarcely to project as 

far backward as the posterior margin of the second thoracic 

segment. Glabella depressed nearly even with the cheeks, about 

two-thirds as long as the entire head, and between one-third and 

one-fourth the breadth of the same behind, but narrowing forward to its subtruncated anterior end, and separated from the 

cheeks on each side and in front by a shallow furrow; occipital 

furrow moderately well defined, and continued as rather deep 

broad furrows along the posterior margin of the cheeks out 

nearly to the points where the facial sutures cut the margin; lateral furrows not clearly defined in the specimens, but apparently 

consisting of four pairs. Facial sutures directed at first, for a 

short distance, forward from the inner anterior end of each eye, 

then curving gracefully outward as they extend forward, until 

near the anterior margin of the head, where they are a little wider 

apart than the distance between the eyes, but again curving 

rather abruptly inward, so as to reach the anterior margin nearly 

on a line with each eye; posteriorly these sutures extend at first 

outward, nearly at right angles to the longitudinal axis, from the 

posterior end of each eye, and then curve gracefully backward 

so as to intersect the posterior margin between one-fourth and 

one-third the distance from the lateral angles, inward toward 

the glabella. Eyes rather depressed, slightly arched outward, 

and separated from each other by a space somewhat less than 

half the entire breadth of the head, and placed less than their 

own length in advance of the posterior margin, and about once 

and a half their length behind the front margin of the head; 

visual surfaces narrow, and not showing any lenses under a good 

magnifier.

Thorax with its length bearing the proportions to that of the 

head, of 79 to 52, and to its own breadth, of 79 to 107, being 

very slightly wider near the middle than in front, and narrowing 

posteriorly, with gently convex lateral margins, from behind the 

middle to the pygidium. Axial lobe depressed, narrow, or only
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 79

about two-thirds the breadth of each lateral lobe at its anterior 

end, and narrowing regularly with straight sides posteriorly; 

segments thirteen, nearly or quite straight, and each with a small 

node or prominence at each end. (In some specimens these 

nodes seem to be wanting, while in others they do not exist on 

all of the segments.) Lateral lobes depressed or nearly flat; 

pleurae almost transverse or marching slightly backward to near 

the extremities, which are abruptly pointed; each with a welldefined furrow, which commences small near the anterior inner 

end and widens and deepens for about half way out, and then 

narrows and becomes more shallow, so as to die out before 

reaching the lateral extremities.

Pygidium subsemicircular, being rounded posteriorly, with a 

narrow, slightly flattened border, and somewhat rounded anterior lateral extremities; length bearing to that of the thorax 

the proportions of 30 to 79, and to that of the head 30 to 52, 

with a breadth of not quite two-thirds of that of the head; 

axial lobe equaling more than two-thirds the length, narrow, 

depressed, and showing more or less distinctly about five segments; lateral lobes much depressed, nearly twice as wide at the 

anterior end as the middle one, each with about three segments, 

which curve a little backward and become obsolete before passing 

upon the narrow, smooth border; segments each provided with a 

comparatively large longitudinal furrow, corresponding to those 

on the pleurae.

Entire surface apparently smooth, excepting fine radiating 

striae on the anterior and lateral portions of the cephalic shield 

that are scarcely visible without the aid of a magnifier.

Whole length, 1.60 inch; breadth of thorax, 1.07 inch; breadth 

of cephalic shield (somewhat flattened by pressure), about 1.12 

inch; length of thorax .79 inch; length of pygidium .30 inch; 

breadth of pygidium .60 inch.

Discussion.—E. kingii (Meek) is represented by 

hundreds of slightly flattened nearly complete specimens. It is characterized by the relatively narrow 

border on the cranidium and pygidium, short genal 

spines on the free cheek, narrow axiaJ lobe on the thorax, 

and short distal thoracic spines.

Occurrence.—Middle Cambrian, Wheeler formation, 

House Range, Utah.

Figured specimen.—Nearly complete carapace, 

USNM 15439d, length, 16 millimeters.

Elrathia? occidentalis (Walcott)

Ptychoparia occidentalis Walcott, 1884, U. S. Geol. Survey 

Mon. 8, p. 51, pi. 10, fig. 5.

Description.—The cranidium of this species was 

described in detail by Walcott (1884, p. 51).

Head within the facial sutures, exclusive of the postero-lateral 

limbs, quadrangular in form; glabella subconical, the sides 

slightly converging towards the rounded front; surface uniformly convex and marked by three pairs of moderately oblique 

glabellar furrows, the two posterior pairs of which are more 

strongly impressed and reach two-thirds the distance to the 

median line, the anterior pair are short and faintly defined; 

occipital furrow distinct; occipital ring rounded and rather 

under the medium size; dorsal furrows well impressed on the 

sides and in front of the glabella; fixed cheeks of medium width, 

not very convex, and sloping away gradually in front and behind; 

ocular ridges well marked; frontal limb extended a little beyond 

the fixed cheeks, slightly convex, and bordered by a flattened

rim that is two-thirds as wide as the width between it and the 

glabella; eye-lobes of medium size; postero-lateral limbs narrow, 

extended, with a strongly marked continuation of the occipital 

furrow just within their posterior margin. The facial suture 

cuts very obliquely across the frontal rim of the head and 

abruptly recurving inward at its interior margin passes slightly 

inward in a direct Hne to the eye-lobe, back of which it is directed outward with a backward curve on the outer third of the 

lateral limb, to the posterior margin of the head, which it cuts 

at a distance from the dorsal furrow equal to the width of the 

base of the glabella.

Discussion.—Resser (1937, p. 10) assigned Ptychoparia 

occidentalis Walcott to Elrathia without a word of comment. Because only the cranidium of this species is 

known, it is practically impossible to give either an 

adequate specific diagnosis or a certain generic identification. The name should probably be restricted to 

the type specimen. The distinct glabellar furrows 

noted by Walcott are probably due in great part to 

the crushed nature of the type specimen.

The glabella has a more strongly rounded anterior 

end, and the cranidium has a relatively wider border 

than that of E. kingii (Meek).

Occurrence.—Middle Cambrian, Geddes limestone of 

Wheeler and Lemmon (1939), Eureka, Nev.

Figured specimen.—Holotype cranidium, USNM 

24612, length, 16 millimeters.

Genus KOCHASPIS Resser, 1935

Kochaspis Resser, 1935, Smithsonian Misc. Coll., v. 93, no. 5,

p. 36. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 611.

Rasetti, 1951, Smithsonian Misc. Coll., v. 116, no. 5, p. 225. 

Paleocrepicephalus Kobayashi, 1935, Tokyo Imp. Univ., Fac. 

Sci., Jour., sec. 2, v. 4, pt. 2, p. 277.

Genotype.—Crepicephalus liliana Walcott, 1886 (p. 

207, pi. 28, figs. 3, 3a, b).

Diagnosis.—Cranidium subquadrate in outline, gently 

to moderately rounded anteriorly. Glabella well defined by dorsal furrow, straight sided or with sides 

slightly bowed outward, tapered forward, bluntly 

rounded anteriorly. Three pairs of deep glabellar furrows present. Occipital furrow deep. Occipital ring 

gently to moderately arched upward. Frontal area 

with distinct brim and border; border gently arched 

upward; marginal furrow shallow on midline, broad, 

deep distally. Width of fixed cheeks more than onehalf width of glabella; prominent ocular ridges present. 

Palpebral lobes situated opposite middle third of glabella, poorly defined by shallow palpebral furrow. 

Length of posterior limbs about equal to width of 

glabella at occipital furrow; marginal furrow deep. 

Anterior course of facial suture nearly straight forward 

from palpebral lobe; posterior course divergent from 

longitudinal cranidial axis.
80 SHOETEE CONTEIBUTIONS TO GENEEAL GEOLOGY

Free cheek and thorax unknown.

Pygidium, excluding spines, subquadrate in outline. 

Axial lobe prominent, distinctly furrowed, variable in 

length; width slightly more than one-half width of 

pleural lobes. Pleural segments coalesced distally to 

form a pair of posteriorly directed marginal spines.

Outer surface of carapace covered with scattered 

large granules; inner surface smooth.

Discussion.—The cranidium of this genus differs from 

that of Kochiella, Poulsen, which it most nearly resembles, by having narrower fixed cheeks and the border 

arched upward instead of downward in longitudinal 

profile.

Pygidia resemble those of Fieldaspis Rasetti but can 

be distinguished by their relatively wider axial lobe, 

deeper pleural furrows and interpleural grooves, and 

lack of a flat or concave border.

Kochaspis augusta (Walcott) 

Plate 17, figure 6

Crepicephalus augusta Walcott [part], 1886, U. S. Geol. Survey

Bull. 30, p. 208, pi. 28, fig. 2a. 

Walcott, 1890, U. S. Geol. Survey 10th Ann. Rept., pt. 1,

p. 653, pi. 96, fig. 9a. 

Walcott, 1916, Smithsonian Misc. Coll., v. 64, no. 5, p. 204,

pi. 29, fig. 6b.

Description.—The holotype of this species is a pygidium described by Walcott (1886, p. 208). "Pygidium 

with a short strong axis crossed by three furrows; 

pleural lobes flattened and marked by the extension 

of the axial furrows; posteriorly the lobes extend into 

points, leaving an arched posterior border between the 

two points of pygidium."

Discussion.—The cranidium originally assigned to 

this species comes from a different locality than the 

pygidium. Their association as parts of the same 

trilobite is not at all certain. The pygidium occurs 

with the types of Kochaspis liliana (Walcott), from 

which it differs by having one less axial segment and 

short, slightly convergent marginal spines.

The cranidium, recently made the type of K. nevadensis by Resser (1935, p. 37), is relatively narrower 

than that of K. liliana (Walcott). The difference is 

not great, and a statistical study of a sufficiently large 

sample of K. liliana (Walcott) might possibly show that 

it is not significant. Such a determination is not 

possible with the material at hand.

Occurrence.—Middle Cambrian, Pioche formation, 

Highland Range, Nev.

Figured specimens.—Holotype pygidium, USNM 

15430, length, 9 millimeters; holotype of K. nevadensis 

Resser, USNM 61643, length, 12.5 millimeters.

Kochaspis liliana (Walcott) 

Plate 17, figures 7, 8, 10, 11

Crepicephalus liliana Walcott, 1886, TJ. S. Geol. Survey Bull.

30, p. 207, pi. 28, figs. 3, 3a, b. 

Walcott, 1890, U. S. Geol. Survey 10th Ann. Rept., pt. 1,

p. 653, pi. 96, figs. 7, 7a-c. 

Walcott, 1916, Smithsonian Misc. Coll., v. 64, no. 5, p. 209,

pi. 29, figs. 5, 5a-c. 

Shinier and Shrock, 1944, Index Fossils of North America,

p. 611, pi. 257, fig. 16.

Kochaspis highlandensis Resser, 1935, Smithsonian Misc. Coll., 

v. 93, no. 5, p. 37.

Description.—Walcott (1886, p. 207) presented a 

detailed description of this species.

Head semicircular in outline and terminating in round, sharp, 

postero-lateral spines of moderate length. Glabella truneatoconical, tapering moderately to the front, height and width at 

the occipital furrow about equal; marked by three pairs of furrows; the two posterior extend obliquely inward and backward 

and the anterior pairs are nearly transverse in direction; the 

anterior pair is often very faintly indicated, and on the glabellas 

of young individuals, 2mm or 3mm in length, the furrows show 

only as faint depressions on the smooth surface; occipital furrows 

broad and well defined; occipital segment strong and moderately 

elevated; dorsal furrows distinct.

Fixed cheeks broad as the glabella opposite the eyes; posteriorly they broaden out in the short postero-lateral limbs, and 

anteriorly merge into the frontal limb, which is of moderate 

width, slightly convex and bordered anteriorly by a flattened 

margin about as broad as the distance from the front of the 

glabella to the slight but distinct depressions between the frontal 

limb and the margin; postero-lateral limbs grooved near the 

posterior margin by a distinct furrow. Eyes lunate, about onethird as long as the length of the glabella; a strong ocular ridge 

extends from the anterior end of the narrow palpebral lobe with 

a slightly forward direction, touching the dorsal furrow nearly, 

but not quite, opposite the antero-lateral angle of the glabella. 

Facial sutures cut the anterior margin on a line with the sides 

of the glabella, and extend obliquely inward and outward across 

the margin and then curve inward and extend to the eye; curving 

around the palpebral lobe, they extend obliquely outward with 

a slightly sigmoidal course to the posterior margin. The associated free cheek is irregularly triangular; marginal border strong 

and produced behind into a medium-sized, sharp spine; central 

area slightly convex, and marked by striae that radiate from the 

base of the eye towards the margin; anteriorly the border narrows 

to a slender point.

Thorax unknown.

Pygidium subquadrilateral in outline, with strong, slightlydiverging spines extending back from the postero-lateral angles; 

sides nearly straight, slightly converging posteriorly to the base 

of the spines; posterior margin a little concave between the spines; 

axial lobe prominent, convex, and reaching five-sixths of the 

distance between the front and back margins; the sides converging very little towards the obtusely-rounded posterior end; 

divided by fine transverse furrows into five segments and an 

obtuse terminal point; the pleural lobes are grooved by the extension of the grooves crossing the axis; the terminal spines 

appear to arise from the extension of the anterior segment of 

the pygidium. There is considerable variation in the strength 

and direction of the postero-lateral spines, but I find this to be 

true of the corresponding spines on Crepicephalus lowensis.
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 81

Surface of head and pygidium with papillae of different size 

scattered over it, sometimes so thickly as to give a granulose 

appearance to it.

Discussion.—K. liliana (Walcott) is characterized 

by having the width of the cranidium between the 

palpebral lobes greater than the axial length, the axial 

length of the border equal to or greater than the axial 

length of the brim, and four axial segments and a pair 

of long slender divergent marginal spines on the pygidium.

The cranidium illustrated by Walcott (1886, pi. 28, 

fig. 3b) from the Pioche formation north of Bennet 

Springs, Highland Range, Nev., was made the type of 

Kochaspis highlandensis Resser. It has the outer surface poorly preserved but agrees in all observable 

characteristics with K. liliana (Walcott) and is considered here as a synonym of that species. The pygidium mentioned by Resser is a small specimen with 

three pairs of short marginal spines. It certainly does 

not belong to Kochaspis and may represeat a species of 

Zacanthoides.

Occurrence.—Middle Cambrian, Pioche shale, Highland Range, Nev.

Figured specimens.—Cotypes: Cranidium, USNM 

15428, length, 15 millimeters; pygidium, USNM 15428, 

length (not including spines), 8.5 millimeters; cranidium, 

called K. highlandensis by Resser, USNM 61640, length, 

11.5 millimeters; free cheek, USNM 61641, width, 6 

millimeters.

Genus MODOCIA Walcott, 1924

Modocia Walcott, 1924, Smithsonian Misc. Coll., v. 75, no. 2,

p. 59.

Walcott, 1925, idem, no. 3, p. 105. 

Shimer and Shrock, 1944, Index Fossils of North America,

p. 629.

Palmer, 1954, in press, Jour. Paleontology. 

Metisia Resser, 1937, Smithsonian Misc. Coll., v. 95, no. 22, p. 19.

Genotype.—Arionettus (Crepicephalus) oweni Meek 

and Hayden, 1861 (p. 436).

Discussion.—The writer has recently (Palmer, 1954, 

in press) described this genus in detail and considered 

Metisia Resser (1937, p. 19) to be a synonym.

Modocia differs from Ehmania Resser, with which it 

has been confused, by having deep dorsal and marginal 

furrows on the cranidium and fewer segments and a 

downsloping margin on the pygidium.

Modocia nevadensis Palmer, n. sp. 

Plate 17, figures 12, 14, 15

Ptychoparia oweni Walcott [not Meek and Hayden], 1884, U. S. 

Geol. Survey Mon. 8, p. 55, pi. 10, figs. 3, 3a.

Description.—Cranidium subtrapezoidal in outline; 

width at palpebral lobes about equal to length; anterior

margin gently rounded. Glabella elongate, tapering, 

rounded anteriorly, well defined by narrow dorsal furrow. Three pairs of broad, shallow glabellar furrows 

present. Occipital furrow straight, deep; depth at sides 

slightly greater than that on median line. Occipital 

ring moderately convex, of nearly constant width. 

Frontal area narrow, subequally divided into moderately to strongly arched border and gently arched brim. 

Marginal furrow distinct, deep; occasional suggestions 

of pair of depressions about opposite posterolateral 

corners of glabella. Fixed cheeks narrow, slightly convex, gently downsloping. Palpebral lobes distinct, 

moderate sized, connected to anterior end of glabella 

by very faint ocular ridges. Posterior limbs sharply 

pointed; length somewhat less than width of glabella 

at occipital furrow. Marginal furrow deep, distinct. 

Anterior course of facial suture straight forward or 

slightly divergent from axial line; posterior course divergent behind eye, gently curving to posterior margin.

Free cheek elongate sub triangular in outline; platform 

about twice as wide as arched, slightly downsloping 

border. Genal spine short, sharply pointed; small 

"spur" on inner margin.

Pygidium transverse in outline; width about twice 

length. Axial lobe short, bluntly terminated, tapered 

slightly, and extended to margin, bears 2 or 3 distinct 

segments. Pleural lobes marked by 5 or 6 pleural and 

interpleural furrows diminishing in strength posteriorly. 

First segment of pygidium often continued laterally 

into short spines. Posterior margin with faint median 

identation. Border poorly developed. Surface of carapace faintly and minutely granular.

Discussion.—Walcott (1884, p. 55) considered this 

species to be identical to Arionellus (Crepicephalus) 

oweni Meek and Hayden from the Deadwood formation 

in the Black Hills of South Dakota and placed it in 

the genus Ptychoparia. He discussed but never described it, and Resser (1935, p. 25), without a word of 

comment, placed it in Ehmania. The Eureka specimens have deep dorsal and marginal furrows on the 

cranidium and a poorly developed pygidial border, both 

considered characteristics of Modocia that differentiate 

it from Ehmania. The cranidium of this species differs 

from that of Arionellus (Crepicephalus) oweni Meek and 

Hayden by being relatively narrower and more strongly 

arched and by having the axial length of the border 

about equal to that of the brim. The pygidium is 

identical in all observable characteristics to the pygidium of that species. The writer considers Arionettus 

(Crepicephalus) oweni Meek and Hayden, 1861, genotype of Modocia, and Ptychoparia oweni Walcott, 1884, 

to be congeneric, but not conspecific, and proposes the 

name Modocia nevadensis Palmer, n. sp., for the specimens illustrated by Walcott.
82 SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY

Occurrence.—Middle Cambrian, Hamburg limestone 

(lower part), Eureka Mining district, Nev.

Figured specimens.—Holotype cranidium, USNM 

24610, length, 9 millimeters; pygidium, USNM 24610, 

length, 5 millimeters.

LITERATURE CITED

Angelin, N. P., 1851, Paleontologia Suecica. Fasc. I—Holmiae. 

Beyrich, E., 1845, Tiber einige bohmische Trilobiten. Berlin. 

Deiss, C. F., 1938, Cambrian formations and sections in part of

Cordilleran trough: Geol. Soc. America Bull., v. 50, p. 951-

1026. 

Hall, James, and Whitfield, R. P., 1877, Paleontology: U. S.

Geol. Expl. 40th Par. Rept., v. 4, p. 199-231. 

Hague, Arnold, 1883, Geology of the Eureka district, Nev.:

U. S. Geol. Survey, 3d Ann. Rept., p. 237-290. 

Hawle, Ignaz, and Corda, A. J. C., 1847, Prodrom einer Monographic der bohmischen Trilobiten. Prag. 

Howell, B. F., 1935, Cambrian and Ordovician Trilobites from

Herault, southern France: Jour. Paleontology, v. 9, no. 3,

p. 222-238.

———— 1937, Cambrian Centropleura vermontensis Fauna of

northwestern Vermont: Geol. Soc. America Bull., v. 48,

no. 8, p. 1147-1210. 

Howell, B. F., and Duncan, Donald, 1939, Middle-Upper

Cambrian transition faunas of North America: Wagner

Free Inst. Sci. Bull., v. 14, no. 1, p. 1-11. 

Jaekel, O., 1909, Tiber die Agnostiden: Deutsche geol. Gesell.

Zeitschr., Band 61, p. 380-401. 

Kobayashi, Teiichi, 1935, The Cambro-Ordovician formations

and faunas of south Chosen. Paleontology. Part 3: Tokyo

Imp. Univ., Fac. Sci., Jour., sec. 2, v. 4, pt. 2, p. 49-344.

———— 1939, On the Agnostids (pt. 1): Tokyo Imp. Univ., 

Fac. Sci., Jour., sec. 2, v. 5, pt. 5, p. 69-198.

1942, On the Dolichometopinae, Tokyo Imp. Univ.,

Fac. Sci., Jour., sec. 2, v. 6, pt. 10, p. 143-205. 

Lake, Philip, 1938, A Monograph of the British Cambrian

trilobites, pt. II: Paleontographical Soc., v. 91, p. 249-272. 

Lochman, Christina, 1938, Middle and Upper Cambrian faunas

from western Newfoundland: Jour. Paleontology, -v. 12,

no. 5, p. 461-477. 

———— 1940, Fauna of the basal Bonneterre dolomite (Upper

Cambrian) of southeastern Missouri: Jour. Paleontology,

v. 14, no. 1, p. 1-53.

1952, in Cooper, G. A., and others, Cambrian stratigraphy

and paleontology near Caborca, northwestern Sonora,

Mexico: Smithsonian Misc. Coll., v. 119, no. 1, p. 60-161. 

Lochman, Christina, and Duncan, Donald, 1944, Early Upper

Cambrian faunas of central Montana: Geol. Soc. America

Special Paper 54, 179 p. 

Lorenz, Th., 1906, Beitrage zur Geologic und Palaeontology von

Ostasien unter besonderer Berucksichtung der Provinz

Schantung in China 2: Palaeontologischer Teil: Deutsche

geol. Gesell. Zeitschr., Band 58, p. 53-108. 

Matthew, G. F., 1899, Studies on Cambrian Faunas, No. 3:

Royal Soc. Canada Proc. and Trans., 2d ser., v. 5, sec. 4,

p. 39-66.

Meek, F. B., 1870, Descriptions of fossils collected by the U. S.

Geological Survey * * *: Acad. Nat. Sci. Philadelphia

Proc. for 1870, p. 56-64. 

———— 1873, Preliminary paleontological report, consisting of

lists and descriptions of fossils, with remarks on the ages of

the rocks in which they were found * * *: U. S. Geol.

Survey Terr. 6th ABU. Rept., p. 429-518.

1877, Paleontology: U. S. Geol. Expl. 40th Par. Rept.,

v. 4, p. 1-197. 

Meek, F. B., and Hayden, F. V., 1861, Descriptions of new Lower

Silurian (Primordial), Jurassic, Cretaceous and Tertiary

fossils collected in Nebraska Terr. * * *: Acad. Nat.

Sci. Philadelphia Proc. for 1861, p. 415-447. 

Pack, F. J., 1906, Cambrian fossils from the Pioche mountains,

Nevada: Jour. Geology, v. 14, no. 4, p. 290-302. 

Palmer, A. R., 1954, in press, The faunas of the Riley formation

in central Texas: Jour. Paleontology. 

Poulsen, Christian, 1927, The Cambrian, Ozarkian and Canadian

faunas of northwest Greenland: Meddelelser om Gronland,

Bind, 70, p. 239-243. 

Rasetti, Franco, 1944, Upper Cambrian trilobites from the Levis

conglomerate: Jour. Paleontology, v. 18, no. 3, p. 229-258.

———— 1948, Middle Cambrian trilobites from the conglomerates 

of Quebec: Jour. Paleontology, v. 22, no. 3, p. 315-339.

———— 1951, Middle Cambrian stratigraphy and faunas of the 

Canadian Rocky Mountains: Smithsonian Misc. Coll. 

v. 116, no. 5, p. 1-270.

1952, Ventral cephalic sutures in Cambrian trilobites:

Am. Jour. Sci., 5th ser., v. 250, p. 885-898. 

Raymond, P. E., 1928, Two new Cambrian trilobites: Am. 

Jour. Sci. 5th ser., v. 15, no. 88, p. 309-313.

——— 1937, Upper Cambrian and lower Ordovician Trilobita

and Ostracoda from Vermont: Geol. Soc. America Bull.,

v. 48, no. 8, p. 1079-1146. 

Reed, F. R. C., 1910, The Cambrian Fossils of Spiti: India

Geol. Survey Mem., ser. 15, v. 17, mem. 1, 70 p. 

Resser, C. E., 1935, Nomenclature of some Cambrian trilobites:

Smithsonian Misc. Coll., v. 93, no. 5, p. 1-46.

———— 1936, Second contribution to nomenclature of Cambrian 

trilobites: Smithsonian Misc. Coll., v. 95, no. 4, p. 1-29.

———— 1937, Third contribution to nomenclature of Cambrian 

trilobites: Smithsonian Misc. Coll., v. 95, no. 22, p. 1-29.

———— 1938a, Cambrian System (restricted) of the southern 

Appalachians: Geol. Soc. America Special Paper 15, p. 1-140

———— 1938b, Fourth contribution to nomenclature of Cambrian 

fossils: Smithsonian Misc. Coll., v. 97, no. 10, p. 1-43. 

1939, The Spence shale and its fauna: Smithsonian

Misc. Coll., v. 97, no. 12, p. 1-29. 

Resser, C. E., and Endo, Riuji, 1937, The Sihian and Cambrian

formations and fossils of southern Manchoukuo: Manchurian

Sci. Mus. Bull. 1, p. 1-474. 

Rominger, C. L., 1887, Description of primordial fossils from

Mt. Stephens, NW. Territory of Canada: Acad. Nat.

Sci. Philadelphia Proc. for 1887, p. 12-19. 

Shaw, A. B., 1952, Paleontology of northwestern Vermont.

II, Fauna of the Upper Cambrian Rockledge conglomerate

near St. Albans: Jour. Paleontology, v. 26, no. 3, p. 458-483.
APPRAISAL OF GREAT BASIN MIDDLE CAMBRIAN TRILOBITES DESCRIBED BEFORE 1900 83

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

America: 837 p., The Technology Press, Massachusetts Institute of Technology.

Stoyanow, Alexander, 1952, in Cooper, G. A., and others, Cambrian Stratigraphy and Paleontology near Caborca, Northwestern Sonora, Mexico: Smithsonian Misc. Coll., v. 119, 

no. 1, p. 49-59.

Vogdes, A. W., 1892, On the North American species of the 

genus Agnostus: Am. Geologist, v. 9, p. 377-396.

Walcott, C. D., 1884, Paleontology of the Eureka District: U. S. 

Geol. Survey Mon. 8, p. 1-64.

———— 1886, Second contribution to the Studies on the Cambrian Fauna of North America: U. S. Geol. Survey Bull. 

30, 368 p.

———— 1888, Cambrian fossils from Mount Stephens, Northwest 

Territory of Canada: Am. Jour. Sci. 3d. ser., v. 36, no. 213, 

p. 163-166.

——— 1889, Description of new genera and species of fossils 

from the Middle Cambrian: U. S. Natl. Mus. Proc., v. 11, 

p. 441-446.

———— 1890, The fauna of the Lower Cambrian or Olenellus zone: 

U. S. Geol. Survey 10th Ann. Rept., pt. 1, p. 515-629.

———— 1908, Cambrian sections of the Cordilleran area. Smithsonian Misc. Coll., v. 53, no. 5, p. 184.

Walcott, C. D., 1913, The Cambrian faunas of China: Carnegie 

Inst. Washington Pub. 54, v. 3, p. 1-276.

———— 1916, Cambrian trilobites: Smithsonian Misc. Coll. v. 

64, no. 5, p. 303-456.

———— 1924, Cambrian and Ozarkian trilobites: Smithsonian 

Misc. Coll. v. 75, no. 2, p. 53-60.

1925, Cambrian and Ozarkian trilobites: Smithsonian

Misc. Coll. v. 75, no. 3, p. 61-146. 

Westergard, A. H., 1946, Agnostidea of the Middle Cambrian

of Sweden: Sveriges geol. undersokning, ser. C, no. 477.

Arsbok 40, no. 1, p. 1-140. 

Wheeler, H. E. and Lemmon, D. M., 1939, Cambrian formations

of the Eureka and Pioche districts, Nevada: Nevada Univ.

Bull., v. 33, no. 3, Geol. and Min. ser. 31, p. 1-60. 

White, C. A., 1874, Preliminary report upon invertebrate fossils:

U. S. Geog. and Geol. Surveys W. 100th Mer. Rept., p.

5-27. 

——— 1877, Report upon the invertebrate fossils collected in

portions of Nevada, Utah, * * *: U. S. Geog. and Geol.

Surveys W. 100th Mer. Rept., v. 4, pt. 1, p. 3-219. 

Whitehouse, F. W., 1936, The Cambrian faunas of northeastern

Australia, parts 1 and 2: Queensland Mus. Mem., v. 11, pt.

1, p. 59-112.

INDEX

[Italic numbers indicate description]

Abrigo limestone, Arizona, trilobites in.-...-_ 76 

Abstract___________--------_.-.. 55

Agnostidae, family_________________ 59-62

Agnostinae, subfamily._,_________________ 60-62

Agnostus americanus............................ 61

bidens.. — ——— ——— —————————— 61,62

interstrictus__._._____________ 57,60 

richmondensis............................... 57, 61

seclusus..—................................. 57,59

Albertella.........................—-.-..-... 69

Alokistocare..................................... 71,76

idahoense...........................__...... 71

laticeps... —...---—........................ 71

packi....................................... 72

piochensis.--..—— 57, 58, 70, 7S: pi. 16, figs. 1, 2, 5 

pomona....................—.—........... 72

prospectense................................. 77

septum..................................... 71

spencense................................... 71

subcoronatum........... 57, 71, 72, 72; pi. 15, fig. 8

Amecephalus................................... 71

piochensis.. ................................ 71

americanus, Agnostus..-........--.............. 61

Arionellus (Crepicephalus) oweni. — ............. 81

Armagnostus................................... 60

Asaphiscus......................________ 73

iddingsi.-................................... 73

laeviceps...... 57, 58, 59, 66, 73, 74; pi. 16, figs. 4, 6

seclusus.......................-———-—_.— 59

wheeleri.....——... —— . 57, 60, 73, 74; pi. 16, fig. 7

ataous, Ptychagnostus...... ___.._.__________ 61,62

Athabaskia.......................... ____________ 66

howetti... ————........... 57, 58, 66; pi. 13, fig. 8

ostheimeri................................... 66

augusta, Crepicephalus.......................... 57,80

Kochaspis..... 57, 58, 69, 80; pi. 17, figs. 7, 8,10,11

Australia, Dinesus stage.--. — .--_-,.-__._. 61

B

Bathyuriscus.................................... 66

howetti.........-..-..................—.— 57,66

(Kootenia) dawsoni......................... 64

prodii ctus................................... 67

Bathyuriscus-Elrathina zone__..._____._-. 56

Battus integer................................... 60

bidens, Agnostus..............._________ 61,62

boccar, Dolichometopus.......................... 67

Glossopleura............................... 68

Bolaspidella.... — ——— —————————— 60,74,75

housensis..........——........ 57, 75; pi. 16, fig. 3

British Columbia, Stephen formation__ _ _ 69,75

O

Chisholm shale, Pioche district, trilobites in__ 57,58 

Clavaspidetta—.————————.—————_ 66

Collecting localities—_. _———————_ 58, fig. 3 

Conocephalites subcoronatus.. ________.. 57, 71, 72 

(Conoeephalites) kingii, Conocoryphe......___ 57,78

Conoeoryphe (Conocephalites) kingii-............ 57,78

kingii————————————————————. 57

(Ptychoparia) kingii.._____.______ 78 

Corynexochoidea, superfamily.. — _..____ 62-66

Page 

Crepicephalus augusta........................... 57,80

liliana..—.............................. 57,79,80

(Loganellus) quadrans.................... 57, 75, 76

(Crepicephalus) oweni, A rionellus............... 81

D

dawsoni, Bathyuriscus (Kootenia')...............

Deadwood formation, South Dakota, trilobites 

in-.... —.........—.—..—.....

Deissella........................................

DeUophthalamus................................

DieeUocephalus expansus........................

quadriceps..................................

Dikellocephalus gothicus...................... 57,

quadriceps.................._...___....__...

wahsatchensis...............................

Dinesus state, Australia_.______-_-____..

Diplorrhina.....................................

Distribution of species, stratigraphic_.... _____

Dolichometopidae, family___________________

81

74,75 

74,75 

57,63

57

64,65 

57,65 

57,64

61

60 

57-58

productus.. ............ ..... ....... ... ......

Dorypigidae, family... __ _ ___ ____ __ _ ...

Dory pyge. .............. ... . ... ...... ............

dunbari, Eldoradia. ............ . .... .............

Dunderberg shale, Eureka district, trilobites in_.

63 

67

62-66 

62 

76 

55

E

Ehmania.--. ................ ....... . ........... 75,81

weedi. ...... ..... ..... ................. . ..... 76

Ehmaniella ......... . ... ....... .... ...... ... . .... 75

quadrans........... 57, 58, 75, 76, 76; pi. 17, figs. 1-5

Eldoradia....................................... 76

dunbari. ... .--...-........ ... . ... . .......... 76

lata....... .................................. 77

linnarssoni-— .......... 57, 58, 77; pi. 16, figs. 9, 10

prospectensis .... ...... ....... 57,58,77; pi. 16, fig. 8

Eldorado limestone _ ... . ___ - ___ __ __ . 55

Elrathia........ ................................. 78

kingii.............. 57, 60, 75, 78, 78, 79; pi. 17, fig. 13

occidentalis— ......... ..... . 57,58,79; pi. 17, fig. 15

Embolimus spinosa ...... ...... .. ..... .... .... ... 69

Eteraspis...... .... . ... . ..... . ............... . ... 73

laeciceps ..—. ..... ... ... .... .... ...... ... .... 73

Eureka district. -_---._-..- __ . __ 55, 56, 65, 74, 76 

trilobites in____________-_. __________________ 58

eurekensis, Kootenia.. ......... ... 57,58,65; pi. 14, fig. 4

expanus, Dicellocephalus. ...... ........... ... .... 57,63

Dolichometopus......... .......... ... . ....... 63

Olenoides— .............. 57,58,63; pi. 14, figs. 5,7

F 

Fieldaspis.— ................................... 69,80

O

Geddes limestone, Eureka District, trilobites in. 56, 58 

Oeragnostetta. ... .... ...... ___________ .. 59

Oeragnostus ......... ..... _____ _____ __ 59, 62

Glossopleura ..... ... ... .... ............. ... ... .. 67

boccar ............ .... . ..... ......... ... .... . 67

producta. .... ..... . .... 57, 58, 67; pi. 13, figs. 7, 9-13

kellocephalus .... .. ................ 57,64,65

H

Hamburg limestone, Eureka District, trilobites 

in————————————————

Highland Range, Nev., trilobites in____......... 58,81

highlandensis, Kochaspis.....———.——.__. 80,81

Holteria—.—— — — . —————.-----... 62,65

problematica. ________ 57,58, 59, 66; pi. 15, figs. 3,4,6

Homagnostus.................................... 60

House Range, Utah, trilobites in.____.__. 57 

housensis, Bolaspidella..._____ 57, 75; pi. 16, fig. 3

Ptychoparia...—————————— 57,74,75,75

Howellaspis...........--... —.........—........ 74, 75

hou-elli, Athabaskia.——.——.—- 57, 58, 66; pi. 13, fig. 8

Bathyuriscus................................ 57,66

Hysteropleura...-.-......-...................... 74, 75

I 

idahoense, Alokistocare....................... —— 71

iddingsi, Asaphiscus—...------------------ —— .. 73

inflatus, Olenoides... __-_-___-_ —— -__._ ——.. 66 

integer, Battus.—.............—......—.___ 60

interstrictus, Agnostus.......................---- 57, 60

Peronopsis———----. — —— — 57,60, pi. 13, fig. 6

Introduction______ —.-.__ — ___.---.--___--- 55-56

K 

kingii, Conocoryphe.............................. 67

Concoryphe (Conocephalites).—.————— 57,78

Elrathia—————- 57, 60,75, 78,78, 79; pi. 17, fig. 3

Ptychoparia.————— —..————————— 78

Kochaspis——— — —————————— 79

augusta—.....- 57, 58,69, 80, pi. 17, figs. 7, 8,10,11

highlandentis—————————————— 80, 81

.-_._--_-__.-_____. 57,58,69,80,80

..... ————— —— 58, 80, pi. 17, fig. 9

KochieUa—-.———————————— —— —— 80

Kootenia..————————————————— 62,64

eurekensis..—————.—— 57,58,65; pi. 14, fig.4 

quadriceps--------—.---- 57,65; pi. 14, figs. 1-3

(Kootenia) dawsoni, Bathyuriscus............... 64

Kormagnostus.-- ——....-..-.—...—-....——.. 59

seclusus.. —— .. ——— - 57,58,59,66; pi. 13, figs. 1-3 

simplex..-.-----.-.- ...—. — — -_._- —— _ 59

s, Asaphiscus— — -...—-----.... —— ---- 57, 

58, 59, 66, 74; pi. 16, figs. 4, 6

Eteraspis.. —...........————————. 73

Ptychoparia——............—..—........ 57, 73

lota, Eldoradia................ _ ————— — —— 77

laticeps, Alokistocare......... — ——— -.--—— 71

liliana, Crepicephalus...-----———...... 67,79,80

Kochaspis....... —............... 57,58,69,80,80

linnarssoni, Eldoradia.—-.. 57,58,77; pi. 16, figs. 9,10

Ptychoparia—..—- __————.......— 57,76,77

Literature cited—.——————————,— 82-83

(Loganellus) quadrans, Crepicephalus..-...... 57,75,76

Lotagnostus....-. ———————————— ————— 61

M

March Point formation, Newfoundland, trilobites in...........—............... 76

Mesagnostus.. ..._. —— ——— - — ———————— 60

85
86 INDEX

Mesophenicus___......

Metisia.. .................

Modocia..-............-..

nevadensis........ 57,1

Page

———_——— — 60 

................... 81

.-—...—.—.— at

9,66.8J; pi. 17, flgs. 12,14

N

Neolenus........ .........._________ 62

(Olenoides)-....— .—„ — — ..____.. 62

senotus________.____________ 62,63

nevadensis, Kochaspis.............. 58,80; pi. 17, fig. 9

Olenoides............. 57,62,63, 64, 64; pi. 14, fig. 9

Modocia.................................... 57,

58,59, 66, 8t; pi. 17, flgs. 12,14 

Paradoxides—....-..____________ 57,64

O 

occidentals, Elrathia.............. 57,79; pi. 17, fig. 15

Ptychoparia................................. 57,79

Ogygiaparabola.............................. 57,67,88

problematica......—...-_________ 57,65-66

producta.................................... 57,67

tpinosa.. — . ______._________ 57,69,70 

Olenoides................................. 62,62,64,65

expansus................. 57, 58,65; pi. 14, flgs. 5,7

inflatus... _______._____.____. 66 

nevadensis............. 57,62,63, 64, 64,pi. 14, fig. 9

quadriceps.................................. 65

serratus..................................... 64

spinosus.................................... 70

typicalis.................................... 57,70

Olenoides wahsatchensis..................... 57,

58, 64, 64,65; pi. 14, flgs. 6, 8

Ophir shale, Oquirrh Range, trilobltes in. ___ 57,58 

Oryctocephalidae, family____. ____. _ 68-69 

Or yctocephalus— ..........__......____... 68

primus................... 57,58,68; pi. 15, flgs. 1,2

ostheimeri, Athabaskia........................... 66

oveni, ArioneUits (Crepicephalus)............... 81

packi, Alokistocare.............................. 72

Paleocrepicephalus.........—................... 79

parabola, Ogygia............................. 57,67,68

Paradoxides nevadensis.......................... 57, 64

proxissimus stage, Sweden_________ 61 

Peronopsinae, subfamily..___________ 59-60 

Peronopsis..-.................................. 60,62

interstrictus.................... 57,60; pi. 13, fig. 6

Piocheshale Pioche district, trilobites In...... 57,58,81

piochensis, Alokistocare.. 57,58,70,72; pi. 16, flgs. 1,2, 5

Amecephalus............................... 57,71

Ptychoparia................................. 72

Page 

pomona, Alokistocare............................ 72

primus, Orytocephalus.....— 57, 58,68; pi. 15, flgs. 1,2

problematica, Holteria_____._______..— 57,

58, 59, 66; pi. 15, flgs. 3,4, 6

Ogygia................................... 57,65-66

producta, Glossopleura.... 57,58,67; pi. 13, flgs. 7, 9-13

Ogygia...................................... 57,67

productus, Bathyuriscus......................... 67

Dolichometopus-..........—..-...-.... — ... 67

prospectense, Alokistocare..--.______-.-. 77 

prospectensis, Eldoradia-— —— 57, 58, 77; pi. 16, fig. 8

Ptychoparia................................ 57, 77

proxissimus stage, Paradoxides, Sweden.....-._. 61

atavus...................................... 61, 62

richmondensis—........ 57, 58, 61; pi. 13, flgs. 4, 5

Ptychoparia.........—.—...... —....... .___ 81

housensis..................-...---.-. 57, 74, 75, 75

kingii_______________-...——.. 78 

laeviceps.................................... 57, 73

linnarsgoni—........................ ..— 57, 76, 77

occidentalis...—........................... 57, 79

oweni....................................... 57

piochensis..........____.....---. ——.. 57, 72

prospectensis............................... 57, 77

quadrans.................................... 76

subcoronata.........—...—................. 72

(Ptychoparia) kingii, Conocoryphe............... 78

Ptychoparioidea, superfamily_.__.__...... 71-82

Q

Quadragnostus.................................. 60

quadrans, Crepicephalus (Loganettus)........ 57, 75, 76

Ehmaniella.......... 57, 58, 76, 76; pi. 17, flgs. 1-5

Ptychoparia................................. 76

quadriceps, Dicellocephalus...................... 57

Dikettocephalus............................. 57, 65

Kootenia.—................ 57, 65; pi. 14, flgs. 1-3

Olenoides................................... 65

Quirrh Range, Utah, trilobites in.............. 57, 58

R

richmondensis, 

Ptychagnostus

................... 57,61

57, 58, 61; pi. 13, flgs. 4, 5

sedusus, Agnostus.............................. 57, 59

Asaphiscus.................._____._. 59

Kormagnostus........ 57, 58, 59, 66; pi. 13, flgs. 1-3

Secret Canyon shale, Eureka District, trilobites

in-...—_———- — -..-—- 55, 58, 66

Page 

septum, Alokistocare............................ 71

serratus, Neolenus.............................. 62, 63

Olenoides................................... 64

simplex, Kormagnostus..............—.......— 59

Sonoraspis............................——.-.. 67

Species, localities collected from...—.———— 58 

original and present taxonomic names of—.. 57 

stratigraphic distribution of...—..——..-. 57-58 

Spence shale member, Ute limestone Wasatcb.

Range, trilobites in.....—.. 57, 58, 71, 75

spencense, Alokistocare-......................... 71

spinosa, Embolimus............................. 69

Ogygia—---—.——----....--------- 57, 69, 70

spinosus, Olenoides...-..... ———————— ——— 70

Zacanthoides-........... 57, 58, 70; pi. 15, flgs. 5, 7

Stephen formation, British Columbia_____ 69, 75 

Stephenaspis.................................... 69

Stereophotographs___._.._—.._ 55, pis. 13-17 

Stratigraphic distribution of species.._.___ 57-58 

subcornata, Ptychoparia................—....... 72

subcoronatum, Alokistocare.. 57, 71, 78, 72; pi. 15, fig. 8 

subcoronatus, Concephalites. .......-..—..... 57,71,72

Sweden, Paradoxides proxissimus stage. -—.. — 61 

Systematic descriptions..------ —————..—- 59-82

T

Taxonomic names of species, original and present-_______-____-_____- 57 

Texas, central..____- — ———-— — „ ——-— 75 

typicalis, Olenoides.............................. 57, 70

Zacanthoides............ 57, 58, 70, 70; pi. 15, fig. 9

U

Ute limestone, Wasatcb. Range, trilobites in. _ 57

W

Wasatch Range, Utah, trilobites in......__.. 57-58

wahsatchensis, Dikettocephalus-................. 57, 64

Olenoides........ 57, 58, 64, 64, 65; pi. 14, flgs. 6,8

uceedi, Ehmania..........................—...— 76

Wheeler formation House Range, trilobites in— 57, 75 

wheeleri, Asaphiscus......... 57, 60, 73, 74; pi. 16, fig. 7

Zacanthoides........... . _____________ 69, 81

spinosus...-—..—-—. 57, 58, 70; pi. 15, flgs. 5, 7 

typicalis...———.———. 57, 58, 70, 70; pi. 15, fig. 9

Zacanthoididae, family—.—.... ——........... 69-71

O
PLATES 13-17
PLATE 13

FIGURES 1-3. Kormagnostus seclusus (Walcott) (p. 59), X4.

Lower part of Hamburg limestone, Eureka district, Nev.

1. Holotype cephalon, USNM 24586, from USGS coll. 58 (OS).

2. Cephalon, USNM 123353a, from USGS coll. 806 (CO).

3. Pygidium associated with cephalon in figure 2, USNM 123353b, from USGS coll. 806 (CO).

4, 5. Ptychagnostus richmondensis (Waleott) (p. 61), X4.

Geddes limestone (of Wheeler and Lemmon), Eureka district, Nev.

4. Cephalon, USNM 123354, from USGS coll. 965 (CO).

5. Pygidium, USNM 123355, from USGS coll. 901 (CO).

6. Peronopsis interstrictus (White) (p. 60), X4.

Holotype, USNM 15405, Wheeler formation, Antelope Springs, House Range, Utah.

7, 9-13. Glossopleura produda (Hall and Whitfield) (p. 67). 

Ophir shale (?), Oquirrh Range, Utah.

7, 10, 11, 13. Cotypes, Xl.5, USNM 15456 a-c, e from USGS coll. 329e (@S). 

9. Pygidium, X1, holotype of Ogygia parabola Hall and Whitfield, here considered a synonym of G. producta (Hall

and Whitfield), USNM 15456d, from USGS coll. 329e (OS). 

12. Nearly complete specimen Xl.5, USNM 123356, from USGS coll. 3c (OS).

8. Athabaskia howelli (Walcott) (p. 66), X2.

Holotype, USNM 15457, from USGS coll. 31 (OS). Chisholm shale, Pioche district, Nev.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 264 PLATE 13

AGNOSTIDAE AND DOLICHOMETOPIDAE
GEOLOGICAL SURVEY PROFESSIONAL PAPER 264 PLATE 14 

t

DORYPYGIDAE
PLATE 14

FIGTJEES 1-3. Kootenia quadriceps (Hall and Whitfield) (p. 65).

Ute limestone, Blacksmith Fork, Bear River Range, ¥tah.

1. Cotype cranidium, X3, USNM 15448a.

2. 3. Cotype pygidia, X2, USNM 15448b, c.

4. Kootenia? eurekensis Resser (p. 65), X4.

Holotype, specimen figured by Walcott (1884, pi. 9, fig. 24) as Dicellocephalus quadriceps, USNM 15449, USGS 

coll. 55b (OS). Geddes limestone (?) of Wheeler and Lemon, Eureka district, Nev.

5. 7. Olenoides expansus (Walcott) (p. 63), X1.5.

Geddes limestone (of Wheeler and Lemmon), Eureka district, Nev. 

5. Holotype cranidium, USNM 15450, from USGS coll. 55b (OS). 

7. Associated pygidium, USNM 15450, from USGS coll. 55b (OS).

6. 8. Olenoides wahsatchensis (Hall and Whitfield) (p. 64), XI.5.

Spence shale member of the Ute limestone, Wasatch Range, Utah.

6. Pygidium of Dikellocephalus? gothicus Hall and Whitfield considered by Walcott, 1886, and subsequent authors

as a part of 0. wahsatchensis, USNM 15447, from USGS coll. 329 (OS). 

8. Holotype cranidium, USNM 15447, from USGS coll. 329 (OS).

9. Olenoides nevadensis Meek (p. 64), XI.

Holotype, the only specimen of this genus ever collected from the Elrathia kingii beds, USNM 15453. Wheeler 

formation, Antelope Springs, House Range, Utah.
PLATE 15

FIGURES 1, 2. Oryctocephalus primus (Walcott) (p. 68), X3. 

Pioche shale, Pioche district, Nev.

1. Cotype cranidium, USNM 15427, from USGS coll. 31a (OS).

2. Cotype pygidium, USNM 15427, from USGS coll. 31a (OS).

3, 4, 6. Holteria problematica (Walcott) p. 66).

Lower part of Hamburg limestone, Eureka district, Nev.

3. Cotype adult cranidium, XI, USNM 24606, from USGS coll. 58 (OS).

4. Cotype immature cranidium, X4, USNM 24606, from USGS coll. 58 (OS). 

6. Rubber cast of cotype pygidium, XI, USNM 24606, from USGS coll. 58 (OS).

5, 7. Zacanthoides spinosus (Walcott) (p. 70), XI.5.

Geddes limestone of Wheeler and Lemmon, Eureka district, Nev.

5. Pygidium, USNM 123352, from USGS coll. 900 (CO).

7. Holotype cranidium, USNM 15451, from USGS coll. 55b (OS).

8. Alokistocare subcoronatum (Hall and Whitfield) (p. 72), X4.

Holotype cranidium, USNM 15442. From the Ute limestone, Blacksmith Fork, Bear River Range, Utah.

9. Zacanthoides typicalis (Walcott) (p. 70), X2.

Holotype, USNM 15454, from USGS coll. 31 (OS). Chisholm shale, Pioche district, Nev.
GEOLOGICAL STJBVEY PKOFESSIONAL PAPEK 264 PLATE 15

/ I "VJ w^v^l <$( ..c f'f^ '•^"-n 

«•- jj-: -;:,} «

,' - ' "* '. ^-L. .

ORYCTOCEPHALIDAE. DORYPYG1DAE, ZACANTHOI Dl DAE, AND PTYCHOPARIOIDEA
GEOLOGICAL SURVEY PROFESSIONAL PAPER 264 PLATE 16

\

PTYCHOPARIOIDEA
PLATE 16

FIGURES 1, 2, 5. Alokistocare piochensis (Walcott) (p. 72). 

Chisholm shale, Pioche district, Nev.

1. Immature specimen, X2, showing variation in width of cheeks with growth, USNM 15434, from USGS coll. 

31 (OS).

2. Complete specimen, X1.5, USNM, from 15434, USGS coll. 31 (OS). 

5. Holotype cranidium, XI, USNM 15434, from USGS coll. 31 (OS).

3. Bolaspidella housensis (Walcott) (p. 75), X4.

Holotype cranidium, USNM 15443. From Wheeler .formation, Antelope Springs, House Range, Utah.

4, 6. Asaphiscus laeviceps (Walcott) (p. 73), X3.

Lower part of Hamburg limestone, Eureka district, Nev.

4. Holotype cranidium, USNM 24614, from USGS coll. 58 (OS).

6. Associated pygidium, USNM 24614, from USGS coll. 58 (OS).

7. Asaphiscus wheeleri Meek (p. 74), X2.

Nearly perfect specimen from topotype material, USNM 15460 Wheeler formation, Antelope Springs, House 

Range, Utah.

8. Eldoradia prospectensis (Walcott) (p. 77), X4.

Holotype cranidium, USNM 15441, from USGS coll. 52a (OS). Secret Canyon shale?, Eureka, district, Nev.

9, 10. Eldoradia linnarssoni (Walcott) (p. 77), X2. 

Secret Canyon shale, Eureka district, Nev.

9. Holotype cranidium, USNM 24611, from USGS coll. 58 (OS).

10. Holotype of Eldoradia lata Resser, here considered a synonym of E. linnarssoni, USNM 90669, from USGS 

coll. 58(OS).
PLATE 17

FIGURES 1-5. Ehmaniella quadrans (Hall and Whitfield) (p. 76), X3.

Figures 1, 2, and 3 are all from one piece of indurated shale.

Figures 4 and 5 show the natural convexity of the specimens. Spence shale, member of the Ute formation, Wasatch 

Range, Utah.

1. Holotype cranidium, USNM 15432, from USGS coll. 329 (OS).

2. Rubber cast of pygidium, USNM 15432, from USGS coll. 329 (OS).

3. Free cheek, USNM 15432, from USGS coll. 329 (OS).

4. Cranidium, USNM 123351a, from USGS coll. 20X (OS).

5. Pygidium, USNM 123351b, from USGS coll. 20X (OS).

6. Kochaspis augusta (Walcott) (p. 80), X2.

Holotype pygidium, USNM 15430, from USGS coll. 31a (OS). Pioehe shale, Pioche district, Nev.

7, 8, 10, 11. Kochaspis liliana (Walcott) (p. 80). 

Pioche shale, Pioche district, Nev.

7. Rubber cast of cotype pygidium X1.5, USNM 15428, from USGS coll. 31a (OS). 

11. Cotype cranidium X1.5, USNM 15428, from USGS coll. 31a (OS).

8. Free cheek, X2, USNM 61641, from USGS coll. 30 (OS).

10. Holotype cranidium, Xl.5, of Kochaspis highlandensis Resser here considered a synonym of K. liliana, USNM 

61640, from USGS coll. 30 (OS).

9. Kochaspis nevadensis Resser (p. 80), Xl.5.

Holotype cranidium, illustrated by Walcott (1886, pi. 28, fig. 2) as that of K. augusta, USNM 61643, from USGS 

coll. 30 (OS). Pioche shale, Pioche district, Nev.

12, 14. Modocia nevadensis Palmer, n. sp. (p. 81), X2.

Lower part of Hamburg limestone, Eureka district, Nev.

12. Holotype cranidium, figured by Walcott (1884, pi. 10, fig. 3) as Ptychoparia oweni, USNM 24610, from USGS

coll. 58 (OS). 

14. Pygidium figured by Walcott (1884, pi. 10, fig. 3a), USNM 24610, from USGS coll. 58 (OS).

13. Elrathia kingii (Meek) (p. 78), X3.

Nearly perfect cotype specimen, USNM 15439d. Wheeler formation, Antelope Springs, House Range, Utah.

15. Elrathia occidentalis (Walcott) (p. 79), Xl.5.

Holotype cranidium, USNM 24612, from USGS coll. 55a (OS). Geddes limestone of Wheeler and Lemmon, 

Eureka district, Nev.
GEOLOGICAL SURVEY PROFESSIONAL PAPER 264 PLATE 17

PTYCHOPAKIOIDEA