Distribution of the Middle Ordovician 

Copenhagen Formation and its 

Trilobites in Nevada 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 

Distribution of the Middle Ordovician 

Copenhagen Formation and its 

Trilobites in Nevada 

By REUBEN JAMES ROSS, JR., and FREDERICK C. SHAW 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 

Descriptions of Middle Ordovician trilobites 

belonging to 21 genera contribute to 

correlations between similar strata 

in Nevada) California) and 0 klahoma 

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON 1972 
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. lVIOR TON, Secretary 

GEOLOGICAL SURVEY 

V. E. McKelvey, Director 

Library of Congress catalog-card No. 78-190301 

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

Washington, D.C. 20402 - Price 70 cents (paper cover) 

Stock Number 2401-2109 
Abstract ______________________________ -------------------------------------------------- Introduction ________________________________________________________________________ _ 

Previous investigations _____________________________________________ _ 

Acknowledgments-------------------------------------------------------· 

Geographic occurrences of the Copenhagen 

Formation and its equivalents _____________________________ _ 

Stratigraphie sections _______________________________________________________ _ 

Antelope Valley, N ev ________________________________________________ _ 

Fossils from hill 8308·----------------------------------------

Fossils from east side Martin Ridge _______________ , 

Clear Creek Canyon, Nev _________________________________________ _ 

Correlation of fossils at Clear Creek Canyon __ 

Hot Creek Canyon, N ev ____________________________________________ _ 

Rawhide Mountain, N ev ____________________________________________ , 

Belted Peak area, Nevada ________________________________________ _ 

Meiklejohn Peak, N ev _____________________ ---------------------------

Northern Inyo Mountains, Calif _____________________________ _ 

Toquima Range, Nev _________________________________________________ _ 

Independence Mountains, N ev _________________________________ _ 

Age of trilobite faunas of the Copenhagen 

Formation and its equivalents _____________________________ _ 

Member A of Merriam ( 1963) ---------------------------------

Member B of Merriam (1963) ---------------------------------· 

Member C of Merriam (1963) ---------------------------------- Caesar Canyon Limestone ________________________________________ _ 

Age of the Copenhagen Formation and its 

equivalents _______________________________________________________________ _ 

Collections and localities ___________________________________________________ _ 

CONTENTS 

Page 

1 

1 

1 

1 

3 

3 

3 

3 

5 

6 

7 

7 

8 

8 

9 

9 

9 

9 

10 

10 

10 

10 

10 

11 

12 

Descriptions of trilobites __________________________________________________ _ 

Genus T1·iarth1·us Green, 1832 .... ------------------------------ Genus Carrickia Tripp, 1965 ____________________________________ _ 

Genus Hypodicranotus Whittington, 1952 _____________ _ 

Genus Robergia Wiman, 1905·----------------------------------

Genus Remoplewrides Portlock, 1843 ______________________ _ 

Genus Robergiella Whittington, 1959 .... ------------------

Genus Isotelus Dekay, 1824·--------------------------------------

Genus Anataphrus Whittington, 1954.--------------------

Genus Nileus Dalman, 1827 _____________________________________ _ 

Illaenid genus, indeterminate __________________________________ _ 

Genus Toemquistia Reed, 1896 .. ------------------------------· Harpid genus, indeterminate ___________________________________ _ 

Genus C1·yptolithoides Whittington, 1941 ______________ _ 

Genus Lonchodomas Angelin, 1854--------------------------

Genus Ampyxina Ulrich, 1922----------------------------------

Genus Raynwndella Reed, 1935.-------------------------------

Genus Ceraurinella Cooper, 1953 .. --------------------------- Genus Ceraurus Green, 1832 ____________________________________ _ 

Cheirurinid genus, indeterminate ___________________________ _ 

Genus Sphaerocoryphe Angelin, 1854 ____________________ _ 

Genus Cybeloides Slocum, 1913.-------------------------------

Calymenid genus, indeterminate _____________________________ _ 

Genus Calyptaulax G. A. Cooper, 1930 __________________ _ 

Genus A'mphilichas Raymond, 1905 ________________________ _ 

Genus Miraspis R. and E. Richter, 1917 ________________ _ 

Genus Primaspis R. and E. Richter, 1917--------------· 

References cited _________________________________________________________________ __ 

Index·-------------------------------------------------------------------------------------

ILLUSTRATIONS 

PLATE 1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

[Plates follow index] 

Tr·iarthnts, Carrickia?, Hypodicranotus, Robergia, and Remo]Jleurides. 

Robergiella and Isotelus. 

Isotelus and Anataphrus. 

Nileus?, illaenid, Toernquistia?, harpid, and Cryptolithoides. 

Cryptolithoides. 

Lonchodomas, Arnpyxina, Raymondella, Ceraurinella, cheirurinid, Ceraurus?, and Cybeloides. 

Sphaerocoryphe, calymenid, Calyptaulax, Amphilichas, and Mi1·aspis. 

Primaspis, Thaleops, and Enc1·inuroides. 

FIGURE 1. Index map showing location of stratigraphic sections in which the Copenhagen Formation 

Page 

14 

14 

14 

15 

15 

17 

17 

18 

19 

21 

21 

22 

22 

22 

25 

25 

25 

26 

26 

27 

27 

27 

27 

27 

28 

28 

29 

29 

31 

Page 

or its equivalents have been recognized in Nevada and California___________________________________________________________________ 2 

2. Outline sketches of cranidium and pygidium of Isotelus copenhagenensis.------------------------------------------------------------ 19 

3. Line tracings of cryptolithid genera and species from North America·------------------------------------------------------------------ 23 

TABLE 

Page 

TABLE 1. Characteristics of isoteloid genera, based on type species .. ---------------------------------------------------------------------------------------- 18 

III 

DISTRIBUTION OF THE MIDDLE ORDOVICIAN COPENHAGEN 

FORMATION AND ITS TRILOBITES IN NEVADA 

By REUBEN JAMES Ross, JR., and FREDERICK C. SHAW 

ABSTRACT 

The Copenhagen Formation of central Nevada is composed 

of a basal sandstone (member A) and two calcareous siltstone 

and silty limestone members (members B and C). 

In areas north and south of Antelope Valley, member B of 

the formation is recognized, but the overlying member C is 

not recognized. To the east and southeast the supposedly older 

uppermost beds of the Antelope Valley Limestone are actually 

equivalent to the lower beds of member B. To the west in two 

thrust sequences of the Toquima Range, the Caesar Canyon 

Limestone of Kay and Crawford and an unnamed limestone 

are probably equivalent to the uppermost Copenhagen Formation. 

Species of 21 genera of trilobites are described from members B and C. Four additional taxa have not been identified 

below familial rank. The most evident change in trilobite 

assemblages takes place about 100 feet below the top of member C in the type locality around Antelope Valley; these 

highest trilobites suggest correlation with the Viola Limestone 

of Oklahoma. The trilobites from lower in member C indicate 

a Wilderness-Barneveld age. 

INTRODUCTION 

The Middle Ordovician Copenhagen Formation was 

defined by Merriam in 1963 (p. 25-27) for highly 

fossiliferous arenaceous, argillaceous, and calcareous 

strata lying above- the Antelope Valley Limestone 

and below the Eureka Quartzite in central Nevada. 

The formation is best developed on both sides of 

Antelope Valley (in the Monitor Range on the west 

and in the Antelope Range on the east, Horse Heaven 

Mountain quad.). 

The formation or its lithologic equivalents can be 

recognized over a great distance from the Independence Mountains of northern Nevada to the northern 

Inyo Mountains of southern California (fig. 1). 

It is the purpose of this report to describe the 

known trilobites of the Copenhagen Formation, to 

summarize the geographic extent of the formation, 

and to update information on the correlation of the 

formation. A few trilobites are described from units 

believed to be correlative with the Copenhagen beds. 

The main responsibility for taxonomy rests with 

Shaw and for stratigraphy with Ross; in neither 

case is the responsibility exclusive. 

PREVIOUS INVESTIGATIONS 

The name Copenhagen Formation was first used 

by Nolan, Merriam, and Williams (1956, p. 28) without definition. Kirk (1933, p. 32-33) was the first to 

recognize the stratigraphic significance of beds later 

assigned to the formation and the first to imply that 

these strata were the lateral equivalents of the Eureka Quartzite. Cooper (1956, p. 127-128, chart 1) 

recognized strata of the formation and was probably 

responsible for calling attention to its members, the 

upper two of which he believed were separated by a 

considerable hiatus. Webb (1958, p. 2339-2345) used 

the name and discussed the extent and correlation of 

the Copenhagen Formation; his correlations were 

basically lithic, with some fossil control. He questioned the existence of a hiatus within the formation. 

Ethington and Schumacher (1969, p. 440-443) 

have given a good review of the definition of the 

Copenhagen Formation, of early interpretations of 

the formation, and of the stratigraphic problems the 

unit poses. They discovered that the uppermost beds 

of the underlying Antelope Valley Limestone contained significant elements of the conodont fauna of 

members A and B of the Copenhagen. This discovery 

parallels that of Ross (1964, p. C78; 1970, p. 31) 

concerning brachiopods and trilobites and indicates 

that the major unconformity proposed by Cooper 

(1956, chart 1) beneath the basal sandstone of the 

Copenhagen Formation in its type locality does not 

exist. 

ACKNOWLEDGMENTS 

Shaw extends particular thanks to the Faculty 

Grants Committee of Mount Holyoke College, which 

supported his work with Ross in the Eureka area in 

1965 and 1967. National Science Foundation Grants 

GA1201 and GA10207 have provided welcome continuing support. Misses Mary McReynolds and Ercelia Kersane assisted ably in many technical tasks, 

including much of the typing. 

1 
2 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

1 20 o 1 1 9 o 118 o 11 r 11 6 o 11 5° 

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_I 

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1

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Test Site 

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100 Ml LES 

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FIGURE 1.-Index map showing location of stratigraphic sections in which the Copenhagen Formation 

or its equivalents have been recognized in Nevada and California. 
STRATIGRAPHIC SECTIONS 3 

C. P. Hughes and R. B. Rickards arranged for the 

loan of the lectotype and other specimens of Toernquistia nicholsoni Reed from the Sedgwick Museum, 

Cambridge University. 

GEOGRAPHIC OCCURRENCES OF THE COPENHAGEN 

FORMATION AND ITS EQUIVALENTS 

The Copenhagen Formation is best developed on 

either side of Antelope Valley. In addition it seems 

to be recognizable in somewhat modified form as far 

north as the Independence Mountains and south and 

southwest to the northern Inyo Mountains of California and to Meiklejohn Peak, Bare Mountain quadrangle, Nevada. 

Northeast of the type locality its equivalents are 

found as dolomitic or calcareous phases of the Eureka Quartzite. To the south in the Ranger Mountains, south of Frenchman Flat on the Nevada Test 

Site, a limy sandstone in the lower half of the 

Eureka Quartzite and the topmost limestone strata 

of the Antelope Valley Limestone are equivalent to 

the parts of member B of Merriam in the type area. 

Between Antelope Valley and the Test Site the lower 

part of the formation persists as calcareous shale, 

silty limestone, and calcareous sandstone. To the 

west both members B and C of Merriam are probably represented by silty limestones in the Toquima 

Range. 

On following pages stratigraphic information is 

reviewed and fossil collections are listed for each of 

the areas wherein the Copenhagen or its equivalents 

are believed to be present. 

STRATIGRAPHIC SECTIONS 

ANTELOPE VALLEY, NEVADA 

(Horse Heaven Mountain quadrangle) 

There seems to be no entirely satisfactory stratigraphic section of the Copenhagen Formation. The 

type section designated by Merriam (1963, p. 26) is 

not completely exposed, as indicated by Ethington 

and Schumacher (1969, p. 441). Fossiliferous sections on the east side of Martin Ridge are cut by a 

half dozen faults (Merriam, 1963, pl. 2; Ethington 

and Schumacher, 1969, fig. 2), and much of the section in each fault block is covered. In a partly successful effort to find a more satisfactory section, Ross 

and L. A. Wilson measured the thickness of the 

Copenhagen on the west side of the Antelope Range 

(Ross, 1970, p. 29-31 and pl. 21) but found that the 

exact contact between members B and C was obscured. However, many of the collections on which 

this paper is based were made in that section. 

Distribution of macrofossils in Ross's collections is 

shown in a previously published stratigraphic diagram (Ross, 1970, pl. 21). A much more complete 

list of brachiopods was published by Cooper (1956, 

p. 128) and quoted by Merriam (1963, p. 26-27), 

but in neither report was the precise occurrence of 

fossils referred to a measured section. The physical 

evidence for a major hiatus between members B 

and C of the formation is unimpressive; it would 

therefore be valuable to have better control on 

stratigraphic ranges of macrofossils within the Copenhagen than is now available. Ethington and Schumacher (1969) have gone to considerable pains to 

obtain the needed control for conodonts. 

Most of the fossils collected from the Copenhagen 

Formation came from a section on the southeast side 

of hill 8308, south of Water Canyon, Antelope Range, 

(SWl;t sec. 24, T. 15 N., R. 50 E., Horse Heaven 

Mountain quad., Nevada), where the total thickness 

is about 490 feet. 

The section measured at hill 8308 is fairly accura'te 

except that the top 133 feet were masked on the line 

of section ; this interval was pieced into the section 

by moving several hundred feet to the west. 

Collections made by Shaw and H. B. Whittington 

in 1965 at this same section were designated SR, 

SR ( -30), and SR-L. (Seep. 14.) 

In 1965 Shaw and Whittington also made collections from Martin Ridge, on the west side of Antelope Valley (Slj2NWt;t sec. 31, T. 16 N., R. 50 E., 

Horse Heaven Mountain quad., Nevada). These are 

designated MR-U for the upper member of the Copenhagen (member C of Merriam, 1963) or MR-L 

for the middle member (member B of Merriam, 

1963). No section was measured. 

FOSSILS FROM HILL 8308 

USGS colin. D1880 CO, Copenhagen Formation, upper 50 ft 

of formation. Also USGS colin. D1912 CO and loc. SR. 

Trilobites: 

Triarthn1s sp. 

Cryptolithoides fittsi Ulrich and Whittington 

Cryptolithoides 'reticulatus n. sp. 

A nataphrus martinensis n. sp. 

Robergia deckeri B. N. Cooper 

Remopleurides sp. 

Robergiella sp. 

Rayrnondella nevadensis n. sp. 

Ceraurinella sp. 

USGS colin. D1913 CO, Copenhagen Formation, high in member C of Merriam, about 50 ft below top of formation. 

Trilobite: 

Lonchodornas sp. 

Loc. SR ( -30), Copenhagen Formation, member C, approximately 130 ft below top. About 360 ft above base of 

member B. 

Trilobites: 

Hypodicranotus n. sp. 

A nataphrus martinensis n. sp. 
4 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

USGS colln. D1879 CO, Copenhagen Formation, member C, 

341 ft above base of member B. 

Brachiopods : 

Sowerbyella merriami Cooper 

Resupinate plectambonitid? 

Trilobite: 

I sotelus sp. 

USGS colln. D1878 CO, Copenhagen Formation, member C, 

337 ft above base of member B. 

Brachiopod: 

Sowerbyella sp. 

Trilobite: 

Isotelus copenhagenensis n. sp. 

USGS colln. D1877 CO, Copenhagen Formation, member C, 

330 ft above base of member B. 

Brachiopods: 

Plectorthis obesa Cooper 

Sowerbyella merriami Cooper 

Cristiferina sp. 

USGS colln. D1876 CO, Copenhagen Formation, member C, 

303 ft above base of member B. 

Brachiopods: 

Oxoplecia nevadensis Cooper 

Sowerbyella sp. (large) 

Cristifer·ina sp. 

Strophomena sp. 

New genus and species resembling Saukrodyctia 

Trilobites: 

Calyptaulax sp. 

Lichid, very large, fragmentary 

Ceraurinid genus, indet. 

USGS colln. D1875 CO, Copenhagen Formation, member C, 

301 ft above base of member B. 

Brachiopods: 

Sowerbyella sp. 

Strophomena? sp. 

Cristiferina sp. 

Trilobite: 

Anataph1·us martinensis, n. sp. 

Sponge: 

Receptaculites sp. 

Ostracodes, abundant 

USGS colln. D1874 CO, Copenhagen Formation, member C, 

277 ft above base of member B. 

Brachiopods: 

Strophomena sp. 

Sowerbyella sp. 

Trilobites: 

Amphilichas aff. A. minganensis (Billings) 

Anataphrus martinensis n. sp. 

Cybeloides sp. 

Calyptaulax sp. 

Sphaerocoryphe sp. 

Hypodicmnotus n. sp. 

Isotelus copenhagenensis n. sp. 

Ostracodes, abundant 

Graptolite: 

Climacogmptus cf. C. phyllophorus Gurley 

USGS colln. D1873 CO, Copenhagen Formation, low in member C, 272 ft above base of member B. Rock in place. 

Brachiopods: 

.Hesperorthis? sp. 

Sowerbyella sp. 

Leptellina? sp. (small species) 

USGS colln. D1873 CO- Continued 

Trilobites: 

Hypodicmnotus n. sp. 

Isotelus copenhagenensis n. sp. 

A uataphrus nwrtinensis n. sp. 

Calyptaula.x sp. 

USGS colln. D1872 CO, Copenhagen Formation, float at 259-

268 ft above base of member B. Almost all of this 

material probably comes from considerably higher in 

the section and is mixed stratigraphically. 

Brachiopods: 

Oxoplecia nevadensis Cooper 

Plectorthis sp. 

Cristiferina sp. 

Bilobia sp. 

Strophomena sp. 

Trilobites: 

Calyptaulax sp. 

Anataphrus martinensis n. sp. 

I sotelus copenhagenensis n. sp. 

Cryptolithoides sp. 

USGS colln. D1871 CO, Copenhagen Formation, float, 225 ft 

above base of member B. 

Brachiopods: 

Orthid, indet. 

Cristiferina cristife,.,·a Cooper 

Eoplectodonta alteTnata (Botts) 

Skenidioides? sp. 

Sowerbyella? sp. 

Binwria? sp. 

Loc. SR-L, Copenhagen Formation, member B. 

Trilobites: 

Calyptaulax cf. C. calliTachis B. N. Cooper 

Nileus? sp. 

USGS colln. D1870 CO, Copenhagen Formation, 193 ft above 

base of member B. 

Brachiopods: 

V alcourea plana Cooper 

Plectambonitid, probably SoweTbyella 

Trilobites: 

I sotelus copenhagenensis n. sp. 

Calyptaulax sp. 

USGS colln. D1869 CO, Copenhagen Formation, 151-156 ft 

above base of member B. 

Brachiopods: 

Valcourea cf. V. plana Guoper 

Valcourea transversa Cooper, large variety 

Multicostella? sp., possibly Plectorthis 

Strongly geniculate strophomenoid 

Cephalopod: 

Siphuncle, indet. 

Fossils from this collection are reminiscent of those from 

the Mountain Lake Member (of Cooper, 1956) of the 

Bromide Formation. 

USGS colln. D1868 CO, Copenhagen Formation, 119 ft above 

base of member B. 

Trilobite, unidentified 

USGS colln. 6790 CO, Copenhagen Formation, approx. 50-70 

ft above top of basal sandstone member A, from float. 

Bryozoans (identified by 0. L. Karklins, written commun., 

Oct. 8, 1969) : 

Chazydictya sp. (2 specimens) 

This form is similar to Chazydictya chazyensis Ross 

(1963, Geol. Soc. America Bull., v. 74, p. 587) described 
STRATIGRAPHIC SECTIONS 5 

USGS colln. 6790 CO, bryozoans- Continued 

from the Chazy Limestone in New York. These are the 

first specimens, if my identification is reasonably correct, that show relationships with the species in the 

standard Chazyan Series of New York and Vermont. 

Another species of Chazydictya or of a related new 

genus with somewhat different morphologic features 

occurs in the collections which R. S. Boardman obtained 

in 1965 from the lower Copenhagen member B of Merriam ( 1963) or its equivalents at the following localities: Mill Canyon (Bimuria zone, uppermost Pogonip, 

below Cryptolithoides zone); east side, Martin Ridge, 

Horse Heaven Mountain quadrangle (member B of 

Merriam, 1963); and at Meiklejohn Peak (Copenhagen? 

Formation (Ross, 1967a, pl. 11)). The specimens from 

Meiklejohn Peak seem to differ slightly from those at 

Mill Canyon and Martin Ridge. Whether these differences are due to the preservation or to morphologic 

structure is difficult to determine because the material 

is fragmentary. 

Phyllodictya cf. P. crystallaria Hinds (2 specimens) 

The same form occurs in USGS colin. D680 CO (from 

the lower part of the Eureka Quartzite in the Ranger 

Mountains (Ross, 1967, pl. 11) ) . 

Stictoporella? sp. form a (2 specimens) 

The generic assignment of this form is tentative; it 

may belong to a new genus. This species appears to 

have a relatively large, explanate zoarium. 

Stictoporellid ( ?) sp. (3 specimens) 

The specimens are very fragmentary but appear to 

differ from those assigned to Stictoporella? sp. 

Pachydictyid? sp. (1 specimen) 

This specimen is somewhat similar to a pachydictyid ( ?) 

form which occurs in USGS colin. D1499 CO from 

Belted Peak. 

Ottoseetaxis sp. (2 specimens) 

According to Helen Duncan, this as a form of Ottoseetaxis Bassler, 1952. The type species of this genus, 

0. bipartitus Bassler, 1952, occurs in the Benbolt Formation of Cooper (1956) near Knoxville, Tenn. However, the material in this collection is too fragmentary 

for making further comparisons with the type. 

Constellaria sp. (1 specimen) 

The specimen is too fragmentary for comparison with 

those in other collections. 

Anolotichia sp. (1 specimen) 

Similar forms occur in USGS colin. D1905 CO from 

Clear Creek Canyon. This appears to be a generalized 

form and may not be significant in correlation. 

Monticuliporid sp. (1 specimen) 

This is an incomplete fragment and cannot be used for 

comparison with those in other collections. 

Trepostome sp. (1 specimen) 

The material is poorly preserved and it is not diagnostic. 

This is an interesting assemblage of cryptostome hifoliates from USGS colin. 6790 CO. All of them are relatively well preserved and developed. As to the age of 

these rocks, the bifoliates indicate that the strata are of 

the same age as the McLish formation in Oklahoma or 

younger. However, the single fragment of a monticuliporid species suggests that the rocks probably are of the 

Bromide age, because the monticuliporids appear for the 

first time in the lowest Bromide shales and limestones of 

Oklahoma (R. S. Boardman, oral commun., 1965). 

460-1% 0- 72 - 2 

USGS colin. D1867 CO, Copenhagen Formation, float at 44 ft 

above base of member B. 

Trilobite: 

Anataph1·us sp. 

USGS colin. D1866 CO, Copenhagen Formation, 35-39 ft 

above base of member B. 

Brachiopods: 

V alcourea sp. 

Plectambonitid 

Trilobite: 

lsotelus? sp. 

USGS colin. D1865 CO, Copenhagen Formation, 29 ft above 

base of member B. 

Brachiopod: 

Sowerbyella? sp. 

USGS colin. D1614 CO, Copenhagen Formation, 24-30 ft 

above base of member B. 

Brachiopod: 

Strophomenoid indet. 

Trilobite: 

Illaenid? indet. 

USGS colin. D1864 CO, Copenhagen Formation, 6-17 ft above 

base of member B. 

Brachiopod: 

Valcourea sp. 

Trilobite: 

lllaenus sp. 

USGS colln. D1863 CO, Copenhagen Formation, 1 ft above 

base of member B. (Same as USGS colin. 6792 CO.) 

Bryozoans (identified by 0. L. Karklins, written commun., 

Oct. 8, 1969) 

Trepostome sp. (2 specimens) 

These specimens are not diagnostic. 

USGS colln. D1862 CO, Antelope Valley Limestone, approximately 35 ft below basal sand of Copenhagen Formation, on southeast side of hill 8308, NE%,SW% sec. 24, 

T. 15 N., R. 50 E., Antelope Range, Horse Heaven 

Mountain quad., Nevada. 

Brachiopods: 

Leptellina cf. L. occidentalis Ulrich and Cooper 

Large plectambonitid? 

Small asaphid pygidium 

FOSSILS FROM EAST SIDE MARTIN RIDGE 

Loc. MR-U, Copenhagen Formation, member C of Merriam. 

Trilobites: 

A nataphrus martinensis n. sp. 

Illaenid sp. 1 

Illaenid sp. 2 

Calyptaulax cf. C. callirachis (Cooper) 

USGS colln. D249a CO, Copenhagen Formation, float from 

member C of Merriam. 

Trilobites: 

Lonchodomas sp. 

Harpid genus indeterminate 

Amphilichas aff. A. minganensis (Billings) 

USGS colln. D286 CO, Copenhagen Formation, float from 

member C of Merriam. 

Trilobites: 

I sotelus copenhagenensis n. sp. 

Ca.lyptaula~e cf. C. callirachis (Cooper) 

Primaspis sp. 
6 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

Loc. MR-L, Copenhagen Formation, member B of Merriam 

(1963). 

Trilobite: 

Calyptaulax cf. C. calli1·achis (Cooper) 

USGS colln. D249c CO, Copenhagen Formation, float derived 

from member B of Merriam (1963). 

Trilobite: 

I sotelus copenhagenensis n. sp. 

CLEAR CREEK CANYON, NEVADA 

(T. 11 N., R. 48 E., Tonopah 2o quadrangle) 

The Copenhagen Formation in Clear Creek Canyon 

is about 70 feet thick, including the basal sandstone 

member, which is 30 feet thick. These figures do not 

agree with those of Lowell (1965, table 1), who considered that the basal 30-foot sandstone was overlain 

by about 105 feet of strata representing both members Band C of Merriam (1963). 

Fossil collections were made from the Copenhagen 

Formation on the north side of the creek and from 

the highest Antelope Valley Limestone on the south 

side. 

USGS colln. D1903 CO, Copenhagen Formation, 38 ft above 

base of member B, topmost exposure beneath Eureka 

Quartzite. 

Brachiopods: 

V alcmn·ea sp. 

Multicostella? sp. 

M acrocoelia sp. 

Bryozoans (identified by 0. L. Karklins, written commun., 

Sept. 26, 1969) : 

Homotrypid sp. (1 specimen) 

This is an incomplete fragment and cannot be compared 

with those forms in other collections. 

Amplexoporid sp. (1 specimen) 

This is also an incomplete fragment, but it appears to 

be vaguely similar to some undescribed forms which 

occur in the Bromide Formation of Oklahoma. 

Conodonts (identified by J. W. Huddle, written commun., 

April 13, 1970) : 

Belodina monit01·ensis Ethington Specimens 

and Schumacher -------------------------------------------------- 4 

Cyrtoniodus flexuosus (Branson and Mehl) ______ 2 

Dichognathus typica Branson and Mehl ____________ 5 

D1·epanodus suberectus (Branson and Mehl) ____ 3 

Ozarkodina cf. 0. tenuis Branson and Mehl ...... 2 

Phragmodus undatus Branson and Mehl ---········· 2 

Sagittodontus robustus? Rhodes -------------------------- 1 

T1·ichonodella cf. T. barbara (Stauffer) ............ 2 

USGS colln. D1904 CO, Copenhagen Formation, from float 37 

ft above base of member B. 

Brachiopod: 

Valcourea sp. 

Trilobite fragments, including problematical piece of frill 

of cryptolithid. 

Bryozoans (identified by 0. L. Karklins, written commun., 

Sept. 26, 1969) : 

Amplexoporid sp. (1 specimen) 

Probably the same species as that which occurs in collection D1903 CO. 

USGS colln. D1905 CO, Copenhagen Formation, from ledges 

in place 37 ft above base of member B. 

Brachiopods: 

Macrocoelia sp. 

Valcourea sp. 

Trilobites: 

N anillaenus sp. 

I sotelus copenhagenensis n. sp. 

Bryozoans (identified by 0. L. Karklins, written commun., 

Sept. 26, 1969) : 

Anolotichia sp. (1 specimen) 

Similar forms occur in the following collections: 

D1614 CO (reported as trepostomes from the Copenhagen Formation, 24-30 ft above the top of basal sandstone (member A of Merriam, 1963), Antelope Range); 

6790 CO, 60ft above the L:\se of member B in Antelope 

Range; in the material obtained by R. S. Boardman in 

1965 from member B on the east side of Martin Ridge, 

Horse Heaven Mountain quadrangle, Nevada, and 

D1466 CO, Saturday Mountain Formation, Idaho. 

Ostracodes (identified by Jean Berdan, written commun., 

July 12, 1968) : 

H ypochilarina? sp. 

Severella? sp. 

Cryptophyllus sp. 

Punctaparchites sp. 

Ostracodes, indet. 

This is an interesting association of ostracodes, but 

not particularly helpful as far as age determinations 

are concerned. Hyperchilarina? and Cryptophyllus both 

occur in the upper part of the Antelope Valley and 

appar~ntly range upward. Punctaparchites occur in the 

Decorah and Bromide Formations, and has also been 

reported in the Leray Formation of Pauquette Rapids, 

Canada. It could range either higher or lower. Severella 

is a Baltic genus, but the identification is queried because only one tecnomorphic specimen was found, and 

the generic characters are based on the heteromorph. 

Conodonts (identified by J. W. Huddle, written commun., 

April 13, 1970) : 

Specimens 

Acontiodus alveolaris Stauffer ---------------------------- 2 

Belodina monitorensis Ethington 

and Schumacher -----···········---·········-·············-······· 4 

Cyrtoniodus flexuosus? (Branson and Mehl) ____ 1 

Dichognathus sp ........................................................ 7 

Distacodus SP---------···-········-·······-------······-·····-··········· 1 

Drepanodus suberectus (Branson and Mehl) .... 1 

Oistodus sp ··-··-··--------------------------------------·················· 1 

Collections D1903 CO and D1905 CO contain part of the 

fauna described from the Copenhagen Formation by Ethington and Schumacher (1969). There is nothing that is 

very definitive, but a correlation with the Ashby-Porterfield 

is reasonable. 

USGS colln. D1906 CO, Copenhagen Formation, 27 ft above 

base of member B. 

Brachiopods: 

Multicostella sp. 

Valcourea sp. 

Sowerbyites sp. 

Macrocoelia sp. 

Trilobite: 

I sotelus sp. 
STRATIGRAPHIC SECTIONS 7 

USGS colin. D1907 CO, Copenhagen Formation, from float 

near base of member B. 

Trilobite: 

Calyptaulax sp. 

USGS colln. D1909 CO, Antelope Valley Limestone, 127 ft 

below basal sandstone of Copenhagen Formation. 

Brachiopods: 

An onwlo rt his cf. A. okla homensis 

Orthambonites sp. 

Conodonts (identified by J. W. Huddle, written commun., 

April 13, 1970) : 

Specimens 

Acodus sp ------------------------------------------------------------------ 2 

Acontiodus sp ---------------------------------------------------------- 1 

Drepanodns suberectus (Branson and Mehl) ____ 3 

Paltodus sp -------------------------------------------------------------- 1 

Paltodus sp -------------------------------------------------------------- 1 

Oistodus contractus Lindstrom ---------------------------- 2 

Scolopodus n. sp ------------------------------------------------------ 3 

USGS colin. D1910 CO, Antelope Valley Limestone, from float 

129 ft below basal sandstone of Copenhagen Formation. 

Brachiopods: 

Anomalorthis cf. A. oklahomensis Ulrich and Cooper 

Desmorthis cf. D. crassus Ross 

Ostracodes (identified by Jean Berdan, written commun., 

July 12, 1968): 

Eoleperditia bivia? 

Hyperchilarina? sp. 

The Eolepm·ditia in this collection is fragmentary and 

cannot be compared with those from other collections. 

Conodonts (identified by J. W. Huddle, written commun., 

April 13, 1970) : 

Specimens 

Acodus cf. A. auritus Harris and Harris __________ 3 

Acodus sp ------------------------------------------------------------------ 1 

Drepanodus suberectus (Branson and Mehl) ____ 6 

Drepanodus suba1·cuatus Furnish ------------------------ 1 

Oistodus cf. 0. lanceolatus Pander ---------------------- 2 

Oulodus sp ---------------------------------------------------------------- 1 

Scandodus n. sp ------------------------------------------------------ 3 

Scolopodus n. sp ________________________________________________________ 1 

USGS colln. D1908 CO, Antelope Valley Limestone, float 170 

ft below basal sandstone of Copenhagen Formation. 

Brachiopod: 

Anomalorthis cf. A. oklahomensis 

Trilobites: 

Illaenus sp. 

Ostracodes (identified by Jean Berdan, written commun., 

July 12, 1968) : 

Eoleperditia sp. cf. E. bivia (White) 

Small, smooth ostracodes, indet. 

The ostracodes in this collection are not well preserved 

and are difficult to work out of the matrix. The Eolepe'rditia appears to be similar to the kind that occurs 

in the upper part of the Kanosh Shale in the Ibex area, 

but I cannot be certain of this because the specimens 

are so poor. One of the smaller ostracodes seems to be 

new, but there is only one specimen, which is not 

enough to work with. 

Conodonts (identified by J. W. Huddle, written commun., 

April 13, 1970) : 

Specimens 

Eo falodus brevis Harris ---------------------------------------- 1 

Dichognathus n. sp -------------------------------------------------- 3 

USGS colin. D1908 CO, conodonts- Continued Specimens 

Distacodus symmetricus Mound -------------------------- 1 

Drepanodus subarcuatus Furnish ------------------------ 2 

Drepanodus suberectus (Branson and Mehl) ____ 4 

Oulodus sp ---------------------------------------------------------------- 2 

"Tetraprioniodus" costatus Mound ---------------------- 3 

Synprioniodina? sp ------------------------------------------------ 3 

Tdchonodella sp ------------------------------------------------------ 1 

New genus ---------------------------------------------------------------- 1 

CORRELATION OF FOSSILS AT CLEAR CREEK CANYON 

With exception of a fragment of a problematical 

cryptolithid trilobite in collection D1904 CO, every 

fossil collected from the Copenhagen Formation allies it with member B of Merriam. Ross is of the 

opinion that this fragment is harpid. It is difficult 

to understand where Lowell discovered Reuschella, 

unless specimens of Valcourea could have been mistaken for that genus. The thickness of member B 

measured by Ross is so different (by 100 ft) from 

that published by Lowell (1965, table 1) that we 

fear we have overlooked some nearby section that is 

more complete than the one in the valley of Clear 

Creek proper. It seems possible, if not likely, that 

figures for Hot Creek and Clear Creek were reversed 

in publication (Lowell, 1965, table 1). Concerning 

conodonts from the Antelope Valley Limestone in 

this section, J. W. Huddle (written commun., April 

13, 1970) commented, 

Collections D1908-D1910 CO are all Middle Ordovician in 

age and are apparently early Middle Ordovician, as they contain species characteristic of the Joins Formation. I have not 

seen some of these species in the previous collections from the 

Antelope Valley. 

HOT CREEK CANYON, NEVADA 

(T. 8 N., R. 50 E., Tonopah 2o quadrangle) 

Lowell (1965, p. 263 and table 1) indicated that 

the Copenhagen Formation was only 20-30 feet thick 

at Hot Creek; on the basis of a very limited number 

of fossils he concluded that the entire formation had 

been compressed into this thickness, which is in contrast to the far greater thickness in the northern 

Monitor Range. 

Ross (1970, p. 17-19 and pis. 20, 21) has shown 

that the Copenhagen Formation at Hot Creek is 

about 90 feet thick and that the fossils are indicative 

of the lower member (member B of Merriam, 1963). 

The upper member (member C of Merriam, 1963) is 

either absent or represented by some part of the Eureka Quartzite. The Eureka is at least three times as 

thick at Hot Creek as in the northern Monitor Range. 

Trilobites found in USGS colin. D1860 CO include: 

Carrickia sp., Remopleurides sp. 2, Anataphrus martinensis n. sp., and Ceraurus? sp. (possibly a cybelid). 
8 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

RAWHIDE MOUNTAIN, NEVADA 

(Ross, 1964, p. C64-C66, C68) 

Although not so recognized previously, the unnamed black shale and underlying 25 feet of dolomitic sandstone beneath the Eureka Quartzite should 

probably be considered as the Copenhagen Formation 

at Rawhide Mountain (Ross, 1964, p. C66). The contained fossils, particularly the ostracodes (Ross, 

1964, p. C68), seem to indicate that the lower part 

(member B of Merriam, 1963) of the formation is 

represented. 

BELTED PEAK AREA, NEVADA 

The Copenhagen ( ?) Formation near Belted Peak 

seems to be about 277 feet thick. In 1964 Ross and 

L. A. Wilson measured the thickness of an overturned section of Ordovician rocks stratigraphically 

below the Eureka Quartzite on the west side of hill 

7089, 2.85 miles southwest of Belted Peak (Ekren 

and others, 1971) (Nevada coord., central zone: E. 

659,650 ft, N. 1,017,300 ft). This section, which is 

at an altitude of approximately 7,040 feet, was revisited in 1966. 

A unit of thin-bedded fossiliferous limestone containing a high percentage of interbedded siltstone 

is poorly exposed 41-44 feet beneath the Eureka 

Quartzite; this unit in turn is underlain by interbeds 

of shale, dolomitic sandstone, quartzose sandstone 

and siltstone, and thin silty dolomite. The section 

follows: 

Eureka Quartzite. 

Copenhagen ( ?) Formation: 

Interval completely masked by quartzite rubble 

Siltstone, dark-yellowish-orange, limy; 

shows relicts of fossils _________________________________________ _ 

Shale, fissile, medium-gray; weathers yellowish 

orange to olive gray. Interbeds of calcareous 

siltstone ________________________ ----------------------- __________________ _ 

Limestone, calcarenitic silty, in thin irregular 

beds. Fossiliferous. Bryozoans abundant. 

USGS colin. D1499 CO from this intervaL _____ _ 

Slope masked by float. In lower 40ft much shale, 

silty calcarenite, and thin quartzite 

chips in float ___________________________________________________________ _ 

Float, composed of siltstone chips weathering 

grayish yellow --------------------------------------------------------

Limestone and dolomite; weather medium gray 

to light olive gray; form resistant ledge _________ _ 

Siltstone, platy, gray; weathers yellowish 

gray to yellowish orange _____________________________________ _ 

Argillite, grayish red _______________________________________________ _ 

Slope covered by float. All float in this interval 

is yellowish orange to grayish orange _______________ _ 

Float composed largely of yellowish-gray 

( 5Y 8/1) very fine quartzite and sandstone 

in thin chips derived from very thin bedded 

rock. Much grayish-red sandstone in lower half 

Feet 

21 

1 

19 

3 

96 

12 

3 

21 

1 

15 

55 

Copenhagen ( ?) Formation- Continued Feet 

Siltstone and very thinly laminated sandstone; 

weathers pale yellowish orange__________________________ 30 

Total thickness of Copenhagen ( ?) 

Formation ------------------------------------------------------ 277 

Pogonip Group: 

Antelope Valley Limestone: 

Dolomite, light-gray; thin bedded in beds 

2-3 ft thick. Some intraformational 

conglomerate -------------------------------------------------- 31 

Not recorded below this unit. 

Fossils from this entire interval are limited to 

USGS colin. D1499 CO but include a considerable 

variety. 

USGS colin. D1499 CO, Copenhagen ( ?) Formation, 41-44 ft 

below base of Eureka Quartzite. 

Brachiopods: 

Multicostella ( ?) sp. 

Falcourea sp. (large) 

Valcourea sp. (small) 

Sowerbyella sp. 

Trilobite: 

Anataphrus cf. A. spurius (Phleger) 

Conodonts (identified by J. W. Huddle, written commun., 

Mar. 3, 1965): 

Specimens 

Belodina cf. B. ornata (Branson and Mehl) ____ 1 

Cordylodus sp ---------------------------------------------------------- 1 

Dichognathus n. sp ------------------------------------------------ 7 

n. sp ------------------------------------------------------------------ 8 

Distacodus sp ---------------------------------------------------------- 1 

Drepanodus sp _____________________ ----------------------------------- 1 

sp ------------------------------------------------------------------------ 1 

sp ------------------------------------------------------------------------ 1 

Phra.gmodus undatus Branson and Mehl ------------ 4 

Prioniodina? sp -------------------------------------------------------- 1 

Trichonodella sp ------------------------------------------------------ 1 

Zygoguatlws sp -------------------------------------------------------- 1 

"This fauna is probably Middle Ordovician in age. In 

New York Phragmodus undatus and Dichognathus appear in the Rockland Formation of Raymond (1914) 

and continue into the Late Ordovician," Huddle noted. 

Bryozoans (identified by 0. L. Karklins, written commun., 

Feb. 23, 1965) : 

About 11 zoaria were thin-sectioned. Four of these 

zoaria are well enough preserved for identification, but 

they belong to undescribed taxa. In the other sectioned 

material the distinguishing features of the wall structures appear to be recrystallized. 

Pachydictyid ( ?) (2 specimens) 

This is a form of a new cryptostome bifoliate genus of 

the family Rhinidictyidae. 

Trepostome (1 specimen) 

This form, probably a new genus, is vaguely similar to 

the diplotrypids. 

Monticuliporid ( 1 specimen) 

This form shows parts of well developed cystiphragms. 

The rest of the wall structures appear to be recrystallized. 

"According to the information made available to me 

(R. S. Boardman, oral commun., 1965) in regard to the 

Simpson Group of Oklahoma, the cryptostome bifoliates, 

including pachydictyid-like forms, appear for the first 
STRATIGRAPHIC SECTIONS 9 

USGS colln. D1499 CO, bryozoans- Continued TOQUIMA RANGE, NEVADA 

time at the base of the lowest McLish shales and lime- (Wildcat Peak quadrangle) 

stones, and the monticuliporids appear for the first 

time at the lowest Bromide shales and limestones," 

Karklins stated. 

Subsequently Karklins (written commun., Sept. 26, 

1969) commented on homotrypid bryozoans from colln. 

D1861 CO, Copenhagen Formation at Hot Creek (Ross, 

1970, p. 18) and noted, "Vaguely similar forms appear 

to be present also in colln. D1499 CO, reported on Feb. 

23, 1965, as a monticuliporid species. These forms suggest that the strata are of Bromide age or younger but 

probably not older than McLish Formation in Oklahoma." 

Most of the fossils indicate equivalence with members A and B of Merriam ( 1963) of the Copenhagen 

Formation, though they are limited to the upper 45 

feet of the 277 -foot unit here assigned to the formation. 

MEIKLEJOHN PEAK, NEVADA 

(Ross, 1964, p. C25, C27, C29, C30; 1967a, pl. 11) 

In two sections at Meiklejohn Peak, Ross (1964, 

p. C25, C29) included 31 feet and 51 feet of sandy 

limestone in a transitional interval in the top of the 

Antelope Valley Limestone and below the Eureka 

Quartzite. Fossils from this interval ally it to member B of the Copenhagen Formation, which it probably represents (Ross, 1967a, pl. 11). These fossils 

(Ross, 1964, p. C27, colin. D820 CO; p. C30, colin. 

D824 CO; 1967a, pl. 11, colin. D1601 CO) include: 

Eofletcheria sp. 

Glyptorthis sp. 

V alcourea sp. 

Sowerbyites sp. 

Sowerbyella cf. S. perplexa Cooper 

Leptellina sp. 

JJf acrocoel,ia sp. 

Protozyga? sp. 

Oxoplecia monitorensis Cooper 

Laticrura cf. L. heteropleura Cooper 

Illaenus cf. I. utahensis 

This interval is correlative with at least the upper 

20 feet of the Antelope Valley Limestone and lower 

90 feet of the Eureka Quartzite in the Ranger Mountains of the Nevada Test Site (Ross, 1967a, pl. 11). 

NORTHERN INYO MOUNTAINS, CALIFORNIA 

(Independence quadrangle) 

The Barrel Spring Formation of the northern Inyo 

Mountains (Ross, R. J., 1964, p. C37, C40; 1967a, pl. 

11; Ross, D. C., 1966) is surely correlative with 

member B of the Copenhagen Formation. The detrital nature of its constituents also relates this unit to 

the Copenhagen, but the resemblance is closer to the 

beds at Rawhide Mountain and Hot Creek Canyon 

than at the type section. 

The Caesar Canyon Limestone described and 

mapped by Kay and Crawford (1964, p. 432-433, pl. 

1) in the Toquima Range is actually considerably 

more than a limestone. As noted by Kay and Crawford, the lower contact at the type locality of the 

Caesar Canyon may be a gradational one with the 

underlying Antelope Valley Limestone. But in addition to the calcarenitic and phosphatic limestone that 

yields Cryptolithoides and graptolites there is a considerable thickness of shale and siltstone enclosing a 

varied trilobite assemblage in the middle of the formation. In fact most of the trilobites listed by Kay 

and Crawford (1964, p. 433) came from these argillaceous beds. The trilobites indicate equivalence to 

member C of the Copenhagen Formation. 

Kay and Crawford (1964, p. 432) reported Bimuria 

from the lower silty limestone of their Caesar Canyon Formation, and this occurrence has been duplicated by Ross. However, it is virtually impossible to 

distinguish lithologically between strata that Kay 

and Crawford assign to the top of the Antelope Valley Limestone and the lower limestone of the Caesar 

Canyon Limestone in their August Canyon sequence. 

It seems probable that the lower and the middle 

members of the Copenhagen are represented in the 

Toquima Range by Antelope Valley or very similar 

lithology. 

In the Mill Canyon sequence (Kay and Crawford, 

1964, pl. 1) at Ikes Canyon (Ross, 1970, p. 21-23, 

pls. 20, 21) an unnamed Ordovician limestone unit 

overlies the Antelope Valley and underlies the Roberts Mountains Formation (Masket Shale of Kay 

and Crawford, 1964) ; that unit is probably equivalent to part of the Copenhagen Formation. 

INDEPENDENCE MOUNTAINS, NEVADA 

(Tuscarora quadrangle) 

In the Independence Mountains north of Taylor 

Canyon, Kerr ( 1962, pl. 1) mapped three stratigraphic sequences of lower Paleozoic rocks separated 

by thrust faults. In the Burns Creek sequence he 

described the Eureka Quartzite as composed of three 

units (Kerr, 1962, p. 445). The upper unit is 440 feet 

of vitreous quartzite. The middle unit is a less resistant impure dolomite 90 feet thick; this unit is fossiliferous. The bottom unit is 25 feet of resistant, 

bench-forming crossbedded sandstone. 

Kerr (1962, p. 445) reported the following fossils 

from the dolomite unit: Receptaculites sp., Calyptaulax strasburgensis (Ulrich and Delo), Ampyx sp., 

lv!aclu,rites sp., Sowerbyella sp., and an orthid brachiopod. 
10 MIDDLE ORDOVICIAN COPENHAGEN FORMAJ'ION AND ITS TRILOBITES 

Kerr's locality is at an approximate altitude of 

8,080 feet on the ridge west of hill 8422 in the 

SW14NE14 sec. 20, T. 40 N., R. 53 E., Tuscarora 

quadrangle. A collection made by Ross in 1967 

(USGS colin. D2173 CO) from this locality includes 

two species of ValcouTea, StTophomena, Sowe1·byella 

sp., and a coarse ribbed orthid brachiopod. Combined 

with those on Kerr's list, these fossils suggest that 

the dolomite is equivalent to member B of Merriam 

of the Copenhagen Formation. 

The Eureka Quartzite in this area is overlain by 

the Hanson Creek Formation, in which C1·yptolithoides and Anataphrus are present with ClimacogTaptus hastatus (USGS colin. D2175 CO) ; C. 

hastatus is abundant in the beds over the Eureka 

in the northern Monitor Range and in the Antelope 

Range. 

AGE OF TRILOBITE FAUNAS OF THE COPENHAGEN FORMATION AND ITS EQUIVALENTS 

MEMBER A OF MERRIAM (1963) 

In the Antelope Valley area, the lower sandstone 

member contains orthocone nautiloids. No trilobites 

from this unit are in the present collections. 

MEMBER B OF MERRIAM (1963) 

Member B of Merriam (1963) was termed the 

"yellow sandstone" by Cooper (1956, p. 128) and 

was thought to be correlative with Cooper's Arline 

Formation of the southern Appalachians. It contains 

SoweTbyites and MacTocoelia, which may also suggest correlation of this unit with beds at the top of 

the Bromide Formation, in the Mountain Lake Member of Cooper (1956), in Oklahoma. 

Few trilobites have been collected from this member of the formation, and they are of little use in 

distinguishing between members B and C. Calyptaulax cf. calliTachis (Cooper), Anataphrus maTtinensis 

n. sp., and I sotelus copenhagenensis range from one 

member into the other. AnataphTus occurs in the 

topmost Antelope Valley Limestone at the Nevada 

Test Site in USGS colin. D710 CO (Ross, 1964, p. 

C19; 1970, pl. 13, figs. 3, 5, 7, 10) and is very common in the type section of the Hanson Creek Formation. Illaenus seems to range from the lower into 

the upper member. 

If any change in trilobite assemblages takes place 

between members B and C, we have yet to find the 

evidence. On the other hand, there is a pronounced 

change within 100 feet of the top of member C. 

MEMBER C OF MERRIAM (1963) 

Member C of Merriam (1963) carries brachiopods 

thought by Cooper (1956) to be similar to those of 

his Oranda Formation of Virginia. The trilobites 

from this upper unit can be divided into two distinct 

assemblages. 

The lower assemblage ranges upward through collections D1879 CO and D1913 CO on the east side of 

Antelope Valley and through similar levels at Martin 

Ridge. 

It includes Isotelus copenhagenensis, AnataphTus 

maTtinensis, and Calyptaulax calliTachis, which range 

upward from the underlying member. A. maTtinensis 

ranges higher. Amphilichas aff. A. minganensis and 

Hypodicranotus n. sp. are two of the more distinctive 

members of this assemblage; the former suggests an 

early Middle Ordovician age while the latter is known 

from strata of Wilderness (DeMott, 1963) or Barneveld (Whittington, 1952) age in North America. It 

should be noted that HypodicTanotus occurs in southwestern Scotland (Tripp, 1965, p. 601-602) in strata 

correlated with the Porterfield-Wilderness Edinburg 

Formation of Cooper and Cooper (1946) of the 

Appalachians. 

The trilobites found in the uppermost 50 feet- in 

the upper assemblage - of the Copenhagen Formation on the east side of Antelope Valley include 

Triarthrus, Robergia, Robergiella, Remopleurides, 

C1·yptolithoides, Raymondella, and Ceraurinella. 

Cryptolithoides, accompanied by Robergia, is 

known from the lower part of the Viola Limestone 

of Oklahoma. The other genera are typical of the 

Edinburg Formation of the southern Appalachians 

(Whittington, 1959, p. 384-387), presumably an older 

unit (Cooper, 1956). 

In eastern North America, Cryptolithus, rather 

than Cryptolitho,ides, appears at about this stratigraphic level, together with calymenids. Graptolites 

of the zone of OrthogTaptus tTuncatus intermedius 

(Berry, 1960) appear in New York and Oklahoma at 

approximately this level and, as discussed below, also 

appear with these trilobites in the Caesar Canyon 

Limestone of the Toquima Range, Nev. Shaw assumes 

that cryptolithinids and graptolites of zone of 0. 

truncatus intermedius are indicative of the start of 

Barneveld time over much of North America, although Fisher (1962) showed that the Barneveld is 

entirely within that zone. 

The simultaneous arrival of older eastern genera 

-for example, TTiarthrus, Raymondella, and the 

others - at this same time in the west may well 

demonstrate facies or faunal province control over 

these latter genera. 

CAESAR CANYON LIMESTONE 

Kay (1962) and Kay and Crawford (1964) proposed the Caesar Canyon Limestone for supposed 

Copenhagen equivalents in the northern Toquima 
AGE OF THE COPENHAGEN FORMATION AND ITS EQUIVALENTS 11 

Range. No accurate sections have been measured, 

because of structural complications and cover (Marshall Kay, oral commun., 1969). Locality GK ("Gatecliff") appears to be stratigraphically lower than 

locality CC, which has yielded Cryptolithoides. Scattered collections have been made by the present writers and by Kay (Kay and Crawford, 1964, table 1). 

Most of the trilobite genera known from the uppermost part of member C of the Copenhagen Formation 

are present in the Caesar Canyon Limestone. They 

show that the Caesar Canyon correlates with the 

topmost strata of the upper member of the Copenhagen. The appearance of Cryptolithoides, a calymenid, and PTimaspis in the Caesar Canyon suggests 

that the age of this fauna is early Barneveld (Fisher, 

1962; Whittington, 1959). 

Graptolites from three collections from the Caesar 

Canyon Limestone have been examined by W. B. N. 

Berry, whose identifications follow: 

USGS colln. D1901 CO. Caesar Canyon Limestone. 

Climacograptus typicaiis 

Diplograptus? sp. 

Orthograptus truncatlls var. strigosus 

Orthograptus truncatus cf. var. intenned,ius 

Orthograptus truncatus var. pertenuis? 

Age: late Middle Ordovician (about Trenton-Eden), Orthograptus truncatus intermedius zone (zone 13). 

USGS colln. D1917 CO. Caesar Canyon Limestone. 

Clhnacograptus typicalis 

Orthograptus sp. (of the 0. truncatus type) (possibly 0. 

tncncatus intermedius) 

Age: late middle Ordovician, 0. truncatus intamedius zone 

(zone 13). 

USGS colln. D2182 CO. Caesar Canyon Limestone. 

Climacograptus sp. (of the C. typicalis type) 

01·thograptus sp. (of the 0. truncatus group; possibly 

both varieties 0. truncatus intennedius and 0. truncatus strigosus are present) 

Age: late Middle Ordovician, 0. truncatus intermedius zone 

(zone 13). 

AGE OF THE COPENHAGEN FORMATION 

AND ITS EQUIVALENTS 

Most of the brachiopods of the formation were 

described by Cooper (1956), but the relative stratigraphic positions where they were collected were 

highly generalized. The abundant bryozoans have yet 

to be described. A valuable biostratigraphic study of 

the conodonts has been published by Ethington and 

Schumacher (1969). 

On the basis of brachiopods, Cooper (1956, p. 128, 

chart 1) correlated the upper member of the Copenhagen with the Oranda Formation of Virginia (Cooper, 1956, p. 81) which he considered to be somewhat 

older than the Sherman Fall Formation of Kay, 

(1937). Cooper considered the middle member to correlate with his Arline and Effna Formations of Virginia. As a result, in Cooper's (1956, chart 1) scheme 

of Middle Ordovician stages the upper member was 

late Wilderness and the middle member was early 

Porterfield. 

Ethington and Schumacher (1969, p. 448-449) 

showed that the conodonts supply much conflicting 

evidence, but in general the evidence is not in discord 

with Cooper's correlations. They warn, however, that 

no correlations in this part of the section can be 

reliable until conodonts from most of the more easterly sections are studied. 

A number of fossils other than trilobites from the 

Copenhagen and its equivalents are identified in the 

preceding stratigraphic sections. Although many of 

the correlations are uncertain, the information from 

bryozoans, ostracodes, and conodonts suggests that 

member B of the Copenhagen can be correlated with 

parts of the Bromide Formation of Oklahoma. The 

Bromide has been assigned by Cooper (1956) to the 

Porterfield-Wilderness transition. Thus this scattered 

information seems to corroborate work by Ethington 

and Schumacher (1969) discussed above. 

Work in progress by Shaw on Simpson Group 

trilobites shows general similarities between trilobites of the middle member of the Copenhagen and 

of the Bromide. The McLish of Oklahoma is hard to 

separate from the Bromide on the basis of trilobites. 

Clearly, however, the Joins and Oil Creek Formations are not demonstrably correlatable to member B 

of the Copenhagen. 

Some of the trilobites described here are also known 

from the Edinburg Formation of Virginia, a unit of 

very long ranging age but basically believed also to 

correlate to the Bromide (Cooper, 1956). Shaw thus 

would argue that a good part of member B of the 

Copenhagen is Bromide or Edinburg age (late Porterfield to early Wilderness of Cooper, 1956). 

The uppermost few feet of the Copenhagen in 

Antelope Valley is clearly, on the basis of trilobites, 

equivalent to the uppermost part of the Caesar Canyon Limestone of Kay and Crawford (1964). Again, 

many of these trilobites also appear in Oklahoma, in 

the Viola Limestone. Similar forms also appear in 

the Oranda Formation of Cooper (1956) in the southern Appalachians and in the Shoreham Member of 

the Sherman Fall Formation of Kay (1937) of New 

York. According to Berry (1960, p. 38), the lower 

part of the Viola Limestone has graptolites of the 

zone of 0. truncatus intermedius, and some of the 

same forms are known from the "Trenton Limestone" at Trenton Falls, N. Y. Strata at this last 

occurrence are partly equivalent to the Trenton Stage 

of Cooper (1956). Ethington and Schumacher (1969, 

p. 448) noted a difference between Caesar Canyon 
12 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

conodonts and those from the Copenhagen Formation further east. However, it is unclear what part 

of the Caesar Canyon Limestone they were referring 

to, and no suggestion was given that the novel genera 

represent a later age. 

Conodonts apparently are scarce in all of member 

C (Ethington and Schumacher, 1969) but do include 

Polyplacognathus ramosa Stauffer and Sagittodontus 

'robustus Rhodes, forms known from the Trenton 

Group (Schopf, 1966) and the Galena Dolomite (Ethington, 1959), respectively. In summary, graptolites 

and trilobites from the uppermost Copenhagen and 

from the Caesar Canyon Formation appear to be 

equivalent to those in the Viola and thus Barneveld 

in age. 

Churkin (1963, p. 424) called attention to the possible correlation of trilobites from the Caesar Canyon 

Limestone with those from the Saturday Mountain 

Formation in Idaho; graptolites from beds adjacent 

to the trilobite-bearing strata were dated by Ross 

and Berry (1963, p. 62-63 and table 1) as middle 

Caradoc, probably Trenton-Eden. 

Most of the sections discussed in this paper deal 

with the Copenhagen Formation and its equivalents 

to the south and west of Antelope Valley. As noted 

by Ross (1970, p. 33-34) at Lone Mountain (west 

of Eureka, Nev.) and northward in the Roberts 

Mountains, the Eureka Quartzite is present, and the 

Copenhagen is difficult or impossible to identify 

lithologically. At Lone Mountain, Ethington and 

Schumacher (1969, fig. 3) showed that member B 

conodonts are present directly below the Eureka in 

beds considered by Ross (1970, p. 33-34 and pl. 21) 

to be basal Eureka. At the type section of the Hanson 

Creek Formation on Pete Hanson Creek in the Roberts Mountains, Cryptolithoides and Anataphrus appear in that formation above the Eureka. The two 

genera also occur in the Hanson Creek Formation in 

the Independence Mountains, east of Tuscarora. It 

seems probable that the Eureka Quartzite is older 

than at Lone Mountain and was being deposited in 

these more northerly areas at the same time as the 

Copenhagen Formation was being deposited farther 

south. The picture is far from clear in the absence 

of good fossil material. 

COLLECTIONS AND LOCALITIES 

(Collections made by Ross unless otherwise indicated) 

USGS colln. D249a CO, Copenhagen Formation, float 

from member C of Merriam (1963). West side 

of Martin Ridge, 3,200 ft south-southwest of hill 

8172, sec. 13, T. 15 N., R. 49 E., Horse Heaven 

Mountain quad., Nevada. Collected by C. W. 

lVIerriam and R. J. Ross, Jr., 1955. 

USGS colin. D249b CO, Copenhagen Formation, 

mixed float from bottom of member C and top 

of member B of Merriam. West side of Martin 

Ridge, 3,200 ft south-southwest of hill 8172, sec. 

13, T. 15 N., R. 49 E., Horse Heaven Mountain 

quad., Nevada. Collected by C. W. Merriam and 

R. J. Ross, Jr., 1955. 

USGS colin. D249c CO, Copenhagen Formation, float 

near middle of member B of Merriam. West side 

of Martin Ridge, 3,200 ft south-southwest of hill 

8172, sec. 13, T. 15 N., R. 49 E., Horse Heaven 

Mountain quad., Nevada. Collected by C. W. 

Merriam and R. J. Ross, Jr., 1955. 

USGS colln. D249d CO, Copenhagen Formation, float 

from lower part of member B of Merriam. West 

side of Martin Ridge, 3,200 ft south-southwest 

of hill 8172, sec. 13, T. 15 N., R. 49 E., Horse 

Heaven Mountain quad., Nevada. Collected by 

C. W. Merriam and R. J. Ross, Jr., 1955. 

USGS colln. 0286 CO, Copenhagen Formation, lower 

part of member C of Merriam. East flank of 

Martin Ridge, approximately 8,000 ft south of 

mouth of Copenhagen Canyon, T. 16 N., R. 50 

E., Horse Heaven Mountain quad., Nevada. 

USGS colin. D1499 CO, Copenhagen Formation, 41-

44 ft below base of Eureka Quartzite. On west 

side of hill 7089, 2.85 miles southwest of Belted 

Peak, Nevada coord., central zone: E. 695,650 

ft; N. 1,017,300 ft, Belted Peak quad., Nevada. 

USGS colin. D1614 CO, Copenhagen Formation, 24-

30 ft above base of member B. Locality same as 

for D1863 CO. 

USGS colin. D1860 CO, Copenhagen Formation, 

equivalent of member B of Merriam, 79 ft above 

base of and 22 ft below top of formation. North 

wall of Hot Creek Canyon, sec. 24, T. 8 N ., R. 49 

E., Tonopah 2° quad., Nevada. 

USGS colin. D1863 CO, Copenhagen Formation, 1 ft 

above base of member B of Merriam, 1963. 

Southeast side of hill 8308, SWl;i sec. 24, T. 15 

N., R. 50 E., Horse Heaven Mountain quad., 

Nevada. 

USGS colin. D1864 CO, Copenhagen Formation, 6-17 

ft above base of member B. Locality sa:me as for 

D1863 CO. 

USGS colin. D1865 CO, Copenhagen Formation, 29 

ft above base of member B. Locality same as for 

D1863 CO. 

USGS colin. D1866 CO, Copenhagen Formation, 35-

39 ft above base of member B. Locality same as 

for 01863 CO. 

USGS colln. D1867 CO, Copenhagen Formation, float 

at 44ft above base of member B. Locality same 

as for D1863 CO. 
COLLECTIONS AND LOCALITIES 13 

USGS colin. D1868 CO, Copenhagen Formation, 119 

ft above base of member B. Locality same as for 

D1863 CO. 

USGS colin. D1869 CO, Copenhagen Formation, 151-

156 ft above base of member B. Locality same as 

for D1863 CO. 

USGS colin. D1870 CO, Copenhagen Formation, 193 

ft above base of member B. Southeast side of 

hill8308, SW1,4 sec. 24, T. 15 N., R. 50 E., Horse 

Heaven Mountain quad., Nevada. 

USGS colin. D1871 CO, Copenhagen Formation, float, 

collected 225ft above base of member B. Much 

of this collection derived from member C. Locality same as for D1863 CO. 

USGS colin. D1872 CO, Copenhagen Formation, from 

float 258-269 ft above base of member B. All 

this collection is probably derived from considerably higher in the formation and is mixed 

stratigraphically. Locality same as for D1863 

co. 

USGS colln. D1873 CO, Copenhagen Formation, 

lower part of member C of Merriam, 272 ft 

above base of member B. Locality same as for 

D1863 CO. 

USGS colin. D187 4 CO, Copenhagen Formation, 

member C of Merriam, 277 ft above base of 

member B. Locality same as for D1863 CO. 

USGS colin. D1875 CO, Copenhagen Formation, 

member C, 301 ft above base of member B. 

Locality same as for D1863 CO. 

USGS colln. D1876 CO, Copenhagen Formation, 

member C of Merriam, 303 ft above base of 

member B. Locality same as for D1863 CO. 

USGS colln. D1877 CO, Copenhagen Formation, 

member C, 330 ft above base of member B. 

Locality same as for D1863 CO. 

USGS colln. D1878 CO, Copenhagen Formation, 

member C, 337 ft above base of member B. 

Locality same as for D1863 CO. 

USGS colln. D1879 CO, Copenhagen Formation, 

member C, 341 ft above base of member B. 

Locality same as for D1863 CO. 

USGS colln. D1880 CO, Copenhagen Formation, 

upper 30-50 ft of formation, member C of Merriam. Southwest side of hill due west of hill 

8308, approximate altitude 8,000 ft, NW1/tSE1,4 

sec. 23, T. 15 N., R. 50 E., Horse Heaven Mountain quad., Nevada. 

USGS colln. D1901 CO, Caesar Canyon Limestone of 

Kay and Crawford (1964), about 3 in. to 1 ft 

thick, above Antelope Valley Limestone lithology. On west side of mouth of north tributary 

to Mill Canyon approximately 1,800 ft eastsoutheast of hill 8725. Nevada coo rd., central 

460-1 ~6 0 - 72 - 3 

zone: E. 465,000 ft; N. 1,551,100 ft, Wildcat 

Peak quad., Nevada. 

USGS colln. D1903 CO, Copenhagen Formation, 38 

ft above base of member B ; topmost exposure 

beneath the Eureka Quartzite. North side of 

Clear Creek Canyon ( p. 6) . 

USGS colln. D1904 CO, Copenhagen Formation, from 

float 37 ft above base of member B. North side 

of Clear Creek Canyon ( p. 6) . 

USGS colln. D1905 CO, Copenhagen Formation, 37 

ft above base of member B of Merriam, north 

side of Clear Creek Canyon (p. 6). 

USGS colin. D1906 CO, Copenhagen Formation, 27 

ft above base of member B. North side of Clear 

Creek Canyon (p. 6). 

USGS colln. D1907 CO, Copenhagen Formation, float 

near base of formation. North side of Clear 

Creek Canyon (p. 6, 7). 

USGS colln. D1912 CO, Copenhagen Formation, upper 50 ft. Same locality as D1880 CO. 

USGS colln. D1913 CO, Copenhagen Formation, from 

top of yellow-weathering limy siltstone just below upper dark shale, member C of Merriam. 

South-southwest side of hill in NE1,4SE1,4 sec. 

23 and NW1,4SW1;4 sec. 24, T. 15 N., R. 50 E., 

Horse Heaven Mountain quad., Nevada. 

USGS colin. D1914 CO, Caesar Canyon Limestone of 

Kay and Crawford, about 50ft below top in shaly 

unit. East side of Caesar Canyon, approximate 

altitude 8,000 ft. Nevada coord., central zone: 

E. 470,200 ft; N. 1,548,400 ft, Wildcat Peak 

quad., Nevada. 

USGS colln. D1915 CO, Caesar Canyon Limestone of 

Kay and Crawford, approximately 35 ft below 

top in shaly unit. East side of Caesar Canyon, 

approximate altitude 8,000 ft. Nevada coord., 

central zone: E. 470,200 ft; N. 1,548,400 ft, 

Wildcat Peak quad., Nevada. 

USGS colin. D1916 CO, Saturday Mountain Formation, approximately 10 ft above quartzite and 

dolomitic quartzite ledge. About 200 yd south of 

mouth of Bruno Creek, altitude 5~940 ft, west 

side of Squaw Creek, NE1,4SE1,4 sec. 8, T. 11 

N., R. 17 E. Idaho coord., E. 375,700 ft; N. 

958,800 ft, Clayton 7lj2-min. quad., Idaho. 

USGS colin. D1917 CO, Caesar Canyon Limestone of 

Kay and Crawford, upper part. East side of 

Caesar Canyon, approximate altitude 8,240 ft. 

Approximate Nevada coord., central zone: E. 

470,000 ft; N. 1,548,600 ft, Wildcat Peak quad., 

Nevada. 

USGS colln. D2182 CO, Caesar Canyon Limestone, 

type section. Approximate altitude 8,000 ft. 

North of Mill Canyon in tributary canyon. N e-
14 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

vada coord., central zene: E. 470,300 ft; N. 

1,547,600 ft, Wildcat Peak quad., Nevada. 

USGS colin. 6790 CO, Copenhagen Formation, float, 

50-70ft above base of member B. Same locality 

as USGS colln. D1863 CO. 

CC, Caesar Canyon Limestone of Kay and Crawford, 

from phosphatic limestone. East side of Caesar 

Canyon. Essentially the same locality as USGS 

colin. D1915 CO. Collectors H. B. Whittington 

and F. C. Shaw, 1965, in company of Ross and 

others. 

GK, Caesar Canyon Limestone from tah~s slope on 

north side of Mill Canyon, near gate between 

two cliffs. This place called "Gatecliff" by Kay 

and Crawford, (1964, pl. 1). Approximate Nevada coord., central zone: E. 469,300 ft, N. 

1,548,000 ft, Tonopah 2° quad., Nevada. Collectors Marshall Kay and others (Kay and Crawford, 1964, pl. 1). 

MR, Copenhagen Formation: L, member B of Merriam; U, member C of Merriam. East side of 

Martin Ridge, S1j2SW%, sec. 31, T. 16 N., R. 50 

E., Horse Heaven Mountain quad., Nevada. Collectors H. B. Whittington and F. C. Shaw, 1965, 

in company of Ross and others. 

SR, Copenhagen Formation, 3 miles north-northeast 

of Segura Ranch. Same locality as USGS colln. 

D1880 CO. A few specimens labeled SR ( -30) 

from 30 ft stratigraphically below D1880 CO. 

SR-L from 100 ft below USGS colin. D1880 CO. 

Collectors H. B. Whittington and F. C. Shaw, 

1965, in company of Ross and others. 

DESCRIPTIONS OF TRILOBITES 

Family OLENIDAE Burmeister, 1843 

Subfamily TRIARTHRINAE Ulrich, 1930 

Genus TRIARTHRUS Green, 1832 

Porterfieldia Cooper. Whittard, 1961, Ordovician trilobites of 

the Shelve Inlier, West Shropshire: Palaeontographical 

Soc. (London), Pt. 5, p. 189. 

Triarthrus sp. 

Plate 1, figure 1 

Figured specimen.-USNM 169601. 

Occurrence.-USGS colin. D1880 CO, Copenhagen 

Formation, member C; USGS colin. D1914 CO and 

loc. GK, Caesar Canyon Limestone. 

Discussion.-Four Triarthrus-like cranidia from 

USGS collns. D1880 CO and D1914 CO and from 

locality GK are present. The largest Caesar Canyon 

specimen (pl. 1, fig. 1) appears to show a nearly 

complete cephalic border on the right side. No trace 

of an eye or of a dorsal facial suture is present. A 

furrow extends from the anterolateral corner of the 

glabella across the fixed cheek posterolaterally to the 

border furrow. T.hese characteristics suggest relationship with Triarthrus caecigenus Raymond (Cooper, B. N., 1953, p. 8-9, pl. 2, figs. 7-10; pl. 19, fig. 

4). The present material is inadequate for detailed 

description. 

Triarthrus caecigenus has been reported by B. N. 

Cooper (1953, p. 9) from strata in Alabama and 

Virginia that have been referred to the Porterfield 

Stage by G. A. Cooper (1956, chart 1). A very similar species has been described by Whittard (1960, 

p. 190-191) from the Lower Llanvirn Hope Shales 

in West Shropshire, England. 

Family KOMASPIDIDAE Kobayashi, 1935 

Genus CARRICKIA Tripp, 1965 

Carrickia. Tripp, 1965, Palaeontology, v. 8, pt. 4, p. 579-580. 

Goniophrys Whittington, 1965, Harvard Univ. Mus. Camp. 

Zoology Bull., v. 132, no. 4, p. 371. 

Carrickia? sp. 

Plate 1, figure 2 

Figured specimen.-USNM 169602. 

Occurrence.-USGS colin. D1860 CO, Copenhagen 

Formation, equivalent of member B, Hot Creek Canyon. 

Discussion.-Only a single, partial cranidium was 

obtained. This specimen possesses a very short (sag.) 

preglabellar field, a long (exsag.) palpebral lobe, and 

a short (sag.), rounded glabella. The length of the 

glabella excluding the occipital ring seems to be 

eight-tenths its width. In specimens assigned to 

Goniophrys breviceps? (Billings) by Whittington 

(1965, pl. 38, figs. 10, 12) this proportion is 73/100-

77 ;100. In Carrickia pelagia Tripp (1965, pl. 81, fig. 

17a) it is 74/100. The same proportion in Ca1·'rickia 

setoni Shaw (1968, pl. 4, fig. 29) is 75j100. In Goniophrys prima Ross (1951, pl. 18, figs. 17, 27), the 

oldest closely related species, the glabellar length to 

width ratio is 111/100. In specimen referred to Carrickia sp. (Ross, 1972, pl. 10, fig. 19) from USGS 

colin. D1994 CO, Orthidiella zone at Meiklejohn 

Peak, the same proportion is 78/100. 

It is possible that Gonioph1·ys is restricted to Early 

Ordovician strata and is distinguished by its narrow 

glabella. If so, Carrickia probably ranges from the 

Orthidiella zone into beds of Porterfield age. The 

only species of Carrickia for which a pygidium is 

known is C. pelagia Tripp (1965, pl. 81, figs. 21a, b). 

That pygidium closely resembles the pygidium of 

Goniophrys prima Ross (1951, pl. 18, figs. 19, 20, 22) 
DESCRIPTIONS OF TRILOBITES 15 

in outline, convexity, and number of axial rings; it 

differs in the failure of the axial furrows to delineate 

the terminus of the axis confluently. The pygidium 

assigned by Shaw (1968, pl. 4, figs. 27, 33) to Carrickia setoni is so small that it must represent the 

immature stage of some trilobite. In the opinion of 

Ross, this is more likely to be a hystricurus-like form 

than a komaspidid; regardless, it has little in common with the pygidium of C. pelagia. 

Family REMOPLEURIDIDAE Hawle and Corda, 1847 

Genus HYPODICRANOTUS Whittington, 1952 

Hypodicranotus n. sp. 

Plate 1, figures 3-7 

This species is represented by two hypostomes, one 

partial cranidium, one complete cephalon with partial hypostome, one pygidium, and one free cheek. 

Cranidium much like that of Hypodicranotus striatulus (Walcott) (Whittington, 1952, pl. 1), but 

glabella somewhat narrower between back ends of 

eyes. Free cheeks have short lateral spines in addition to genal spines; lateral spines extend backward 

about same distance as genal spines and are not much 

bigger than genal spines. -

Hypostome much like that of H. striatulus but has 

fewer longitudinal ridges on ventral surface of forked 

prongs (compare pl. 1, fig. 7 with Whittington, 1952, 

pl. 1, fig. 7). 

Pygidium composed of articulating half-riD;g, single axial ring with backward swept pleural spines, 

and semielliptical terminal piece. Pleural spines directed straight backward, their tips overlapping 

front seven-tenths of terminal piece. Bertillon markings pronounced on terminal piece, transverse with 

convex side forward. 

Dimensions of JJygidium.-(USNM 169603a) 

Length (sag.) : 3.4 mm 

Width (trans.) : 4.0 mm 

Width without pleural spines: 3.1 mm 

Length (sag.) axial ring: 0.7 mm 

Length (sag.) terminal piece: 2.2 mm 

Width (trans.) terminal piece: 2.7 mm 

Figured specimens.-USNM 169603a, b; 169604; 

169605. 

Occurrence.-Copenhagen Formation,, member C 

of Merriam, USGS colin. D1873 CO, 272 ft above 

base of formation, USGS colin. D187 4 CO, 277 ft 

above base of formation. SR ( -30), 30 ft below 

D1880 CO, or approximately 130 ft below top of 

formation. 

Discussion.-Although the material available is 

hardly adequate for the description of a new species, 

it clearly does not represent any species that has 

been previously described. The great difference in 

size of the lateral spines on the cephalon immediately 

distinguishes the Copenhagen species from H ypodicranotus striatulus, in which the lateral spines extend 

back about half the length of the thorax. 

The lateral spines in H. missouriensis (Bradley, 

1930, pl. 30, figs. 4, 6, 8) are stouter than in the 

species described here, but smaller than in H. striatulus. The hypostome has fewer surface ridges than 

in H. striatulus and in that respect may resemble a 

specimen described by Roy (1941, p. 155, fig. 114) 

from Baffin Land. 

The pygidium is better preserved than any previously reported for the genus. 

The stratigraphic significance of the genus has 

been noted by Whittington (1952, p. 3, 8), who considers it of Trenton age; he further comments that 

he has collected from the Viola Limestone of Oklahoma Hypodicranotus, Cryptolithoides, and Robergia, 

an association duplicated here. The free cheek described by Tripp (1965, p. 582-583, pl. 80, fig. 16) 

from the Albany Mudstone (Girvan District, Ayrshire, Scotland) possesses a short lateral spine similar to that of the Copenhagen species; it is the oldest 

known representative of the genus- that is, of Porterfield age. A hypos tome of H ypodicranotus has also 

been reported by Tripp from the Stinchar Limestones 

of the Girvan District (1967, p. 48, pl. 1, fig. 24). 

Genus ROBERGIA Wiman, 1905 

Robergia occurs over a considerable stratigraphic 

range in the Ordovician, according to Lenz and 

Chu~kin (1966, fig. 3), from basal Llanvirn to 

Ashgill. Two species are pre-Caradoc. One of these 

species is R. micropthal-mus (Linnarson) from the 

Ogygiocaris shales of Sweden (Whittington, 1950, 

p. 543-544, pl. 71, figs. 1-8) of Late Llandeilo age; 

it is the type species of the genus. The other is 

R. schlotheimi (Billings) from the Middle Table 

Head Formation of Newfoundland (Whittington, 

1965, p. 375-377, pl. 40, figs. 9-12, and pl. 41). Both 

species are characterized by exsagittally long palpebral rims, the front ends of which extend in front of 

the distal ends of lateral glabellar furrows 3p. In 

both species, glabellar furrows 2p extend laterally 

well within the arc of the palpebral rims. 

In later species the palpebral rims are shorter, and 

the glabellar furrows are excluded from the field 

bounded by the palpebral rim and a chord through 

its ends. These differences may seem trivial, but they 

have stratigraphic significance. Furthermore, Robergia yukonensis, believed by Lenz and Churkin to be 

the youngest representa;tive of the genus, seems to 

possess a shallow sagittal furrow on the glabella 

(Lenz and Churkin, 1966, p. 41, pl. 4, and pl. 5, figs. 
16 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

1, 2, 4, 5), a feature not found in any other species. 

Although this furrow has obviously been accentuated 

by crushing in some specimens, as noted by Churkin 

(in Lenz and Churkin, 1966, p. 41), nothing like it 

appears in the Nevada specimens. 

The relative age of the Nevada and Yukon species 

is of considerable interest. Lenz and Churkin placed 

their association of Robergia yukonensis, Cryptolithoides sp., and A1npyxina salmoni in the Ashgill 

on the basis of associated graptolites. There is some 

question concerning this dating, simply because the 

association of Robergia, Cryptolithoides, and Ampyxina is of Trenton age everywhere else that it 

has been found. Recently Toghill (1970, p. 10), 

working with Ingham in southern Scotland, has 

shown that the Ashgill-Caradoc boundary probably 

lies within the zone of Dicellog'raptus anceps, higher 

than previously believed. This may result in reassignment of the trilobite association to the Caradoc, but 

it does not solve the problem of its age relative to 

occurrences of the same association in Nevada and 

Oklahoma. 

Robergia deckeri B. N. Cooper 

Plate 1, figures 16-21 

Robergia deckeri B. N. Cooper, 1953, Geol. Soc. America Mem. 

55, p. 23-24, pl. 2, figs. 1-6; pl. 19, figs. 1, 2. 

Only cranidia and pygidia known. Cranidial width 

(trans. at palpebral lobes) about five-sixths cranidial length (sag.) ; length (sag.) of tongue about 

equal to length (sag.) of median area; maximum 

width of tongue four-fifths maximum width of median area. Glabellar furrow 3p opposite anterior end 

of palpebral rim, proximal end curving posteriorly 

parallel to furrow 1p; furrow 2p longer and more 

transverse than furrows 1p and 3p. Basal glabellar 

lobe is formed by occipital furrow and furrow 1p, is 

slightly trapezoidal in outline, and possesses independent convexity. Occipital ring with typical swelling 

on lateral flank and median tubercle on anterior slope. 

Pygidium distinctive, having length ( exsag. 

through longest marginal spine) only two-thirds of 

maximum width (trans. at anterior end). Overall 

outline of pygidium subrectangular. Width (trans.) 

of axis at anterior end three-elevenths of total pygidial width, axis tapering posteriorly to end at 

two-thirds total pygidial length (sag.) ; maximum 

number of axial rings counted equals four plus triangular terminal nub. Pleural field essentially flat, 

crossed by two interpleural ridges which rise from 

the first and second axial furrows respectively; anterior ridge forms proximal edge of outer pygidial 

spine, posterior ridge joins margin proximal to second pygidial spine. Second marginal spine longest on 

pygidium; inner spine short and unassociated with 

interpleural ridge. Pleural area anterior to first interpleural furrow nearly forming an equilateral triangle. Doublure wide and covered with terrace lines; 

other details not known. (See pl. 1, fig. 9.) Entire 

exoskeletal surface smooth. Two immature pygidia 

from locality D1880 CO are assigned to R. deckeri 

because of the relative abundance of this species at 

the locality. 

Figured specimens.-USNM 169607 a-c; 169608a-c. 

Occu1-rence.-USGS colin. D1880 CO, Copenhagen 

Formation, upper 100 ft of formation, member C of 

Merriam. Caesar Canyon Limestone at Caesar Canyon, loc. CC; Caesar Canyon Limestone, loc. GK. 

Discussion.-Robergia deckeri has been noted by 

Decker and Cooper from the basal Viola Limestone 

near Sulphur and near Bromide, Okla. Similar pygidia are reported (Cooper, 1953) from the upper 

part of the Edinburg Formation near Harrisonburg, 

Va. Present material consists of three pygidia from 

the Caesar Canyon Limestone at Caesar Canyon, three 

cranidia from the same locality, and two cranidia 

and two juvenile pygidia from USGS colin. D1880 

CO. Several cranidia from the Caesar Canyon at 

"Gatecliff" resemble this species but occur with pygidia evidently belonging to R. major, so they are 

assigned to that species. 

The Nevada specimens are indistinguishable from 

those figured by Cooper (1953) from the Viola. The 

nonparallel nature of the 2p glabellar furrow and the 

short, broad pygidium with prominent interpleural 

ridges are the principal distinctive features of this 

species. Were it not for differences in the course of 

the 2p furrow, cranidia of Rober·gia would be notoriously difficult to separate. An instance of this confusion is given above and in the following discussion 

of R. major. 

Robergia major Raymond, 1920 

Plate 1, figures 8-15 

Robergia major Raymond, 1925, Harvard Coli. Mus. Comp. 

Zoology Bull., v. 67, no. 1, p. 60-61, pl. 3, figs. 6-10. 

Robergia major Raymond. Cooper, B. N., 1953, Geol. Soc. 

America Mem. 55, p. 22-23, pl. 8, figs. 7-11. 

Robergia major Raymond. Whittington, 1959, Harvard Coli. 

Mus. Comp. Zoology Bull., v. 121, no. 8, p. 428-431, 

pl. 18, figs. 1-22, 25. 

Cranidial features basically as in other species of 

Robergia. Three pairs lateral glabellar furrows parallel, particularly at their proximal ends; pair 2p the 

longest. Pairs 1p and 3p almost same length; but 3p 

tends to be slightly shorter. Palpebral rims extend 

as far forward as distal ends of glabellar furrows 

3p. Free cheeks and thorax not found. 
DESCRIPTIONS OF TRILOBITES 17 

Pygidium subrectangular in outline. Maximum 

exsagittal length equal to or slightly greater than 

width. Axis composed of six rings and terminal piece. 

Axial length%-% sagittal length of pygidium. Pleural 

field narrow (trans.) , crossed by interpleural ridges 

trending nearly straight posteriorly at their distal 

ends. 

Figured specimens.-USNM 169606; AMNH 

29106-112 incl. . 

Occurrence.-Loc. GK ("Gatecliff"), Caesar Canyon Limestone of Kay and Crawford (1964). From 

talus slope on north side of Mill Canyon, Toquima 

Range. All specimens collected by Marshall Kay and 

associates. USGS colin. D1914 CO, Caesar Canyon 

Limestone of Kay and Crawford, about 50ft below 

top of shaly unit, east side of Caesar Canyon. 

Discussion.-Of the specimens described here 

three cranidia and four pygidia came from the Cae~ sar Canyon Limestone in Mill Canyon, about 20 

yards east of the "Gatecliff" (Kay and Crawford, 

1964, pl. 1). The pygidia, each with an axis composed 

of six rings plus terminal piece, indicate a close 

relationship with Robergia major Raymond as described and illustrated by Raymond (1925, p. 60-61, 

pl. 3, fig. 8). According to Whittington's (1959, p. 

429) description of R. major, only five axial rings 

may be distinguished; Cooper (1953, p. 23) on the 

other hand stated that the pygidial axis was composed of "7 or 8 segments." The pygidium of R. 

schlotheimi (Billings) (Whittington, 1965, p. 376, 

pl. 41, figs. 9, 10) has a much shorter axis but is 

similar in outline. In R. yukonensis Lenz and Churkin the pygidium possesses an axis of five rings and 

an outline that is basically semicircular. 

The present cranidia not only resemble those of 

Robergia majm· Raymond as described and illustrated by Cooper (1953, p. 23, pl. 8, figs. 8, 10, 11) 

and Whittington (1959, p. 429, pl. 18, figs. 3, 4, 5) 

but also those of Robergia schlotheimi ·(Billings) 

(Whittington, 1965, pl. 41, figs. 5, 8). In R. yukonensis, glabellar furrows tend to be parallel, as they 

are in R. major· and R. schlotheimi, but all three are 

about equal in length. 

As noted under the discussion of R. deckeri, cranidia in different species of Robergia are nearly impossible to differentiate. A single cranidium of the 

R. deckeri type occurs at "Gatecliff" associated with 

cranidia assigned to R. major. Possibly these two 

species could be considered sexual dimorphs differing 

only in the width of pygidia, but the present material 

is inadequate to solve the problem. 

R. major- occurs somewhat lower than R. decker-i 

in the Appalachian section. This may also be the case 

in Nevada, as the material from Caesar Canyon is 

from the uppermost part of the formation of the 

same name, except for one pygidium. 

Genus REMOPLEURIDES Portlock, 1843 

Remopleurides sp. 1 

Plate 1, figure 23 

A single cranidium is the basis for this description. Cranidial length (sag.) equal to width (max. 

trans. across palpebral lobes) ; tongue width twothirds width of median area. Palpebral rim length 

(exsag.) two-thirds total cranidial length (sag.). 

Occipital ring length (sag.) about one-sixth total 

cranidial length (sag.). Entire cranidial surface covered with fine granules. 

Figured specimen.-USNM 169609. 

Occwrrence.-Float from member B of Copenhagen Formation; near USGS colin. D1880 CO. 

Discussion.-Because this specimen has a relatively narrow (trans.) tongue, it probably does not 

belong to Hypodicranotus. 

Remopleurides sp. 2 

Plate 1, figures 22, 24, 25 

This description is based on a single complete 

cephalon. Greatest width (trans.) of cranidium located opposite cranidial midlength; width (trans.) 

slightly greater than length (sag.) of cranidium. 

Convexity of glabella in lateral view strong; in anterior view, moderate. Anterior tongue of glabella 

markedly convex in transverse profile, so that glabella protrudes well ahead of front ends of eyes. 

Width of glabella (trans.) between eye lobes 1.15 

times its length (sag.) exclusive of occipital ring, 

1.6 times its width at anterior tongue, and 1.5 times 

width (trans.) of occipital ring. Arc of palpebral 

rims evenly curved. Glabellar furrows 1p and 2p 

indicated by smooth lines in otherwise granular surface. Genal spines short, based toward rear of free 

cheeks. 

Figured specimen.-USNM 169610. 

OccurTence.-USGS colin. D1860 CO, Copenhagen 

Formation, 21-23 ft below base of Eureka Quartzite, 

Hot Creek Canyon, Nev. 

Discussion.-Outline of cranidium and lateral convexity are not unlike those of Remopleur-ides simulus 

Whittington, but the anterior tongue is more narrowly convex. The free cheeks have genal spines 

based like those of R. eximius Whittington and lack 

the anterior spine of R. simulus. 

Genus ROBERGIELLA Whittington, 1959 

Robergiella sp. 

Plate 2, figures 1, 2 

Only cranidia known. Length (sag.) equal to total 

width (maximum at palpebral rim). Median area 
~8 MIDDLE ORDOVICIAN -COPEN•I:IAGEN FORMATION AND ITS TRILOBITES 

broad, length- (sag.) to width (trans.) ratio three":' 

fifths. Three pairs of glabellar furrows well developed on median glabellar area. Anterior pair of 

furrows, 3p, shallowest and at anterior edge of median area; others ev~nly spaced with respect to each 

other and occipital furrow. Furrows 1p curved and 

strongly convex. Palpebral rim broad; width (trans.) 

of each rim about one-tenth total maximum cranidial 

width. Tongue at maximum width (trans.)' nearly as 

broad as median area; length (sag.) about one-third 

total cranielial length. Fossula present in axial furrow just anterior to maximum width of tongue. 

Preglabellar area and anterior area of fixed cheek 

very narrow and uniform in width. Occipital ring 

length (sag.) less than half of width (trans.) ; one 

enlarged median tubercle present on anterior slope 

of ring. Entire surface of cranidium (except furrows 

and palpebral rim) covered with small tubercles. 

Figured specimens.-USNM 169611, 169612. 

Occurrence.-USGS colin. D1880 CO, Copenhagen 

Formation, upper 100ft, member C of Merriam, east 

side of Antelope Valley. Collection CC, Caesar Canyon Limestone of Kay and Crawford, top of type 

section in Caesar Canyon, Toquima Range. 

Discussion.-Two cranidia were obtained from 

member C of the Copenhagen and three from the 

highest strata of the Caesar Canyon Limestone. This 

appears to be the first record of Robergiella in the 

Ordovician of the Great Basin. Absence of parts 

other than the cranidi urn prevents specific assignment; but on the basis of the general size and character of the glabellar furrows, these forms closely 

resemble R. sagittalis Whittington from the Edinburg Formation (of Cooper and Cooper, 1946) of 

Virginia. The Nevada material differs in having a 

granulate or tuberculate surface ornament. 

Family ASAPHIDAE Burmeister, 1843 

Genus ISOTELUS Dekay, 1824 

Isotelid fragments are known from member B and 

from the lower and middle parts of member C of the 

Copenhagen Formation at a number of localities. 

Most: of the material appears assignable to a .single 

species and is described below;as such. Generic assignme:pt, is more difficult, because this species possesses characteristics intermediate between those of 

.at least I sot(3lus and I soteloides and perhaps other 

genera as well. A qualitative comparison of these 

genera is given in table 1. 

Jaanusson (1953; 1959, in Moore, p. 0339-0350) 

and Whittington (1965) have discussed the classification. of isotelid genera at length. Nearly every 

exoskeletal detail has been utilized for systematic 

subdivision of the group. Nevertheless, as Whittington (1965) and Shaw (1968) have noted, discrimination of the genera involved is difficult at best. 

Isotelus copenhagenensis n. sp. 

Plate 2, figures 3-11; plate 3, figures 1-3; text figure 2 

Cephalon probably subtriangular in outline; length 

(sag.) estimated to be one-half width (trans.) across 

genal angles. "Glabella" low and indistinct; occupies 

posterior 0.80 length (sag.) of cranidium. Estimated 

width (trans.) of glabella at posterior margin about 

0.32 total cephalic width (trans.) across genal angles. 

Preglabellar field a broad (trans. and sag.) flat area 

without well-defined border. Glabella narrows between eye lobes, so that width is 0.50 glabellar length. 

Anterior width (trans.) of glabella exceeds 0.75 glabellar length (sag.), but width (trans.) at posterior 

cephalic border is less than 0.75 glabellar length 

(sag.). Anterior of glabella bluntly (135°-140°) 

pointed. 

Eyes positioned entirely behind transverse line 

through glabellar midpoint. 

Eye lobes erect, nearly one-half of total height of 

each free cheek in lateral view (pl. 3, fig. 2), and 

short ( exsag.) ; located three-tenths sagittal cranidial 

length from posterior cephalic margin. Width 

(trans.) of cranidium at palpebral lobes 0.80-0.85 

cranidial length (sag.). Posterior part of each fixed 

cheek slightly wider (trans.) than posterior width 

of glabella, crossed by shallow posterior border furrow. Anterior branch of facial suture diverging only 

TABLE 1.- Characteristics of isoteloid genera, based on type species 

Posterior 

cephalic 

border 

furrow 

Axis Hypos tome Cephalic 

border 

Isoteloides ....................... Fixed Narrow ........................... Rounded ...................... Well defined, cheek. flat. 

Eye 

location 

Pygidium Pygidium 

doublure border 

Mid-length __________________ ? ................................ Flat. 

I sotelus. --------------------...... None .. ---. __ .. ____ .------ _____ .. .Broad ..... _________________________ Parallel Poorly defined, Posterior _____________________ simple V _________________ A !most 

sided. flat. absent. Nevada sp ...................... Fixed Inter- .... do ................................... do ... -----·--------------------.. ·--do .................................. do ... -----·-----------·-----Do. cheek. mediate. Megalaspides ................. None ............................ Narrow ........................... Distinctive .................. Well defined, 

flat. Lannacus ........................ Like Megalaspides but approaching Isoteloides-type pygidium. 

Stegnopsis ...................... Fixed N arrow ___________________________ Distinctive __________________ W ell defined, 

cheek 

and 

occipital 

ring. 

flat. 

About mid- Similar to Do. 

length. above. ---------·---------------------------- ? ____________________ .......... Flat. 

Posterior _____________________ Similar to 

Nevada 

species. 

Do. 
DESCRW,'l'IONS OF T:RILOBITES 19 

slightly anterolaterally, so that sides ·Of cranidium 

are nearly parallel, sutures joining anteriorly at 

angle of 100°-110°. Free cheek with rounded genal 

angle; no border furrow or flattened border like area 

present except where adjacent to flat preglabellar 

field. Surface ornament of fine pits. Posterior notch 

of · hypostome occupying one-half of total sagittal 

length; anterior part of notch nearly round, posterior 

margins of notch diverging at about 20°-25°. Terrace 

lines present parallel to margin on hypostome surface. 

At Jeast eight segments present; axial width 

(trans.) about one-third total segment width. Pleural furrow well incised almost to axial furrow. 

Pygidial outline subtriangular; length (sag.) 0.70 

to 0.8 maximum anterior width (trans.). Axis raised 

FIGURE 2. - Outline sketches of cranidium and pygidium 

of I sotelus copenhagenensis based on plate 2, figures 

4, 7. 

above pleural field; width (trans.) at anterior end 

0.25 to 0.30 total pygidial width, tapering posteriorly, 

ending in blunt point; axial length (sag.) 0.75-0.80 

pygidial length (sag.). Slight segmentation on .axis 

on some immature specimens. Pleural field smooth, 

very slightly flattened along posterior margin. Doublure of uniform width, occupying distal one-fourth 

of pygidium, carrying typical asaphid ventral bulge, 

proximal edge a simple rounded "V" posterior to 

axis (pl. 2, fig. 6). 

Holotype.-USNM 169614. 

Paratypes.-USNM 169613; 169615a, b; 169616a, 

b, c, d; 169617; 169618a, b; 169619; 169620. 

Occurrence.-Copenhagen Formation, USGS colln. 

D249c CO, float, member C; D286 CO, member C; 

D1870 CO, member B; D1872 CO, float; D187 4 CO, 

member C; D1878 CO, member C; D1905 CO, member B, Clear Creek Canyon. Caesar Canyon Limestone, USGS coHn. D1914 CO, shaly unit. 

Discussion.-This species differs from others of 

I sotelus (table 1) only in the possession of a border 

furrow along the posterior of the cephalon on either 

side of the glabella, and in this single regard it resembles Isoteloides. 

Isotelus copenhagenensis differs from I. gigas Hall, 

as described by Ross (1967b, p. B3, B5; text fig. 3; 

pl. 1, figs. 1-11; pl. 2, figs. 1-4), in having less divergent anterior facial sutures, a better defined glabella and posterior cephalic border furrow, a narrower indentation of the hypostome, and a somewhat 

narrower pygidial axis. The outline of the cephalon 

and pygidi urn seems to be about the same, as are 

features of the pygidial doublure. 

I. copenhagenensis differs markedly from I. harrisi Raymond (Shaw, 1968, p. 57-58; pl. 21, figs. 

13-16; pl. 22, figs. 1-9) in having a different course 

of the anterior facial suture, poorer development of 

maculae on the hypostome, a narrower posterior indentation, a more triangular outline of the pygidium, 

and more prominently erect eyes. Eyes are farther 

apart than in Raymond's species. 

Genus ANATAPHRUS Whittington, 1954 

A nataphrus Whittington, 1954, Geol. Soc. America Mem. 62, 

p. 141. 

Homotelus Raymond. Esker, 1964, Oklahoma Geol. Notes, v. 

24, no. 9, p. 195-209. 

Isotelus Dekay. Ross, 1967, U.S. Geol. Survey Prof. Paper 

523-D, p. D12. 

Isotelus Dekay. Ross, 1970, U.S. Geol. Survey Prof. Paper 

639, p. 78. 

Whittington (1954, p. 141) erected Anataphrus 

for forms possessing no visible axial furrows, low 

eyes, and a narrow ventrally directed rim on the 

cephalic border. Here we include in Anataphrus 
20 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

Whittington several highly convex asaphids with 

narrow nonconcave borders. Some of these have very 

faint, incomplete axial furrows. 

A nataphrus seems to range from the Porterfield to 

the Barneveld Stage of Fisher (1962). The type 

species, A. borraeus Whittington, from Baffin Island, 

may be younger but is probably of Barneveld age. 

.A. bromidensis Esker from the Pooleville Member of 

Cooper (1956) in the Bromide Formation in Oklahoma is of Wilderness age, as is the new species 

A. martinensis from the Copenhagen Formation. A. 

martinensis may also be represented in the type section of the Hanson Creek Formation. Anataphrus 

vigilans Meek and Worthen and A. gigas Raymond 

from the Maquoketa Shale are probably of Maysville 

age. Probably the oldest species recorded is A. spurius (Phleger) from the Barrel Spring Formation of 

the northern Inyo Mountains, Calif.; A. spurius is 

also recorded from the lower part of the Eureka 

Quartzite and uppermost Antelope Valley Limestone 

in the Ranger Mountains (Ross, 1967a, p. D12, pl. 4, 

figs. 6-9; 1970, p. 78, pl. 13, figs. 3, 5, 7, 10). These 

last occurrences are probably of Porterfield age but 

could be somewhat older. 

Raymond (1920, 1925) proposed Homotelus to include several similar forms. H omotelus Raymond, as 

pointed out by Whittington (1950, p. 552), is based 

on a type species with relatively prominent concave 

cephalic and pygidial borders and thus does not fulfill the original concept of the genus; Raymond, himself (1920, p. 286), did not consider it "a good genus" 

for that reason. 

Esker ( 1964) retained the use of H omotelus for 

isoteloid trilobites displaying two pairs of glabellar 

furrows and differentiated species within the genus 

on the basis of furrow position. Because furrows or 

corresponding pits are very difficult to see on most 

such specimens, it seems more practical to return to 

use of characteristics of the border originally used 

by Raymond (1920, p. 286) and elaborated further 

by Whittington. We would follow Whittington (1950, 

p. 552) in restricting Homotelus to the type species, 

H. ulrichi, and reassign H. bromidensis Esker to 

Anataph1·us as suggested by Ross (1970, p. 78). 

Specimens of A. bromidensis (Esker) collected by 

Shaw in the Criner Hills, Okla., display barely distinguishable glabellar furrows - including one set 

opposite the midpoint of the eye lobe- counter to 

Esker's original description. As the trilobite cephalon 

probably bore as many as six pairs of appendages, 

and because the attachment points on some specimens are very poorly defined (Whittington, 1950, 

fig. 5), variable development of glabellar furrows in 

asaphids appears to have been common, even within 

a species. 

Whittington (1954, p. 141) objected to the use of 

Vogdesia for these relatively featureless forms because the type species, V. beat'si, from the Chazy 

Group of New York, possessed eye stalks, broad shallow axial furrows, and a concave border on the pygidium, and it supposedly lacked a border on the free 

cheek. Shaw (1968, p. 59-60) discussed V. bearsi, 

noting that a pygidium with a concave border had 

been incorrectly assigned to the species by Raymond. 

The characteristics of the eye, degree of development 

of the cranidial axial "furrows, and details of the 

border of the free cheek thus remain the only characteristics separating Vogdesia from this group of 

smooth convex asaphids. 

In Shaw's opinion, these characteristics are obviously gradational with those of such species as 

Vogdesia? obtusus (Hall) from the Chazy Group of 

New York (Shaw, 1968). Shaw believes that Nileaides perkinsi (Raymond) (Shaw, 1968, p. 59, pl. 

19, figs. 8-11) represents the ultimate in this trend 

towards a smooth exoskeleton. Thus, Shaw chose to 

restrict Vogdesia to species lacking an obvious narrow border- that is, the Chazy Group species V. 

bearsi (Raymond) and V.? obtusus (Hall) (Shaw, 

1968, p. 59-62) -and to restrict Nileoides to extremely smooth forms. 

In the opinion of Ross, Vogdesia differs from Anataphrus in having larger palpebral lobes and in 

better definition of the pygidial axis in decorticated 

specimens. 

Anataphrus martinensis n. sp. 

Plate 3, figures 4-16 

Dorsal exoskeletal outline suboval; cephalon wider 

(trans. at genal angle) than pygidium by ratio of 

about four-thirds. Cephalon broadly semicircular in 

dorsal view, extreme border coarsely and concentrically striated along ventral edge; cephalic length 

(sag.) slightly over one-third of maximum width 

(trans.). Cranidium narrow (trans.), width at palpebral lobes three-halfs cranidial length (sag.) ; 

small median tubercle present just anterior to posterior margin; "axial furrow" present as shallow 

trough circling proximal base of eye lobe. Sagittal 

cephalic profile increases in convexity anterior to eye 

lobe. Palpebral lobe minute, located opposite cranidial midlength (sag., dorsal view). Anteriorly facial 

sutures diverge, curving distally to width equal to 

width of palpebral lobe, then recurve sharply to 

join cephalic margin at sagittal line; posteriorly, 

sutures run nearly straight posterolaterally, distal 

segment arcing to posterior cephalic border so that 
DESCRIPTIONS OF TRILOBITES 21 

posterior cranidial width (trans.) is 1.6 width at 

palpebral lobes. Eye lobe stands above cephalon in 

lateral profile; visual surface extends almost completely around lobe, so that some facets are directed 

proximally; visual surface separated from rest of 

free cheek by shallow furrow which joins "axial 

furrow" on proximal side of eye lobe. Distal part of 

free cheek evenly convex, dropping steeply to margin; narrow rim constituting only border; genal 

angle broadly rounded. 

Hypostome not known. Cranidial doublure folded 

under cranidium; rear edge cut away at hypostomal 

suture, which shows that anterior width (trans.) of 

hypostome 1.6-1.7 sagittal width of doublure. Sagittal width of doublure equals width (trans.) of cranidium between elevated palpebral lobes. 

Number of thoracic segments eight; length of segment (sag.) about one-twelth width (trans.), tapering distally; articulating half-ring short (sag.), ring 

furrow broad (sag.) and shallow. Axial furrow absent on exterior surface of thorax, its theoretical 

position indicated on internal mold at about threefourths distance (trans.) from sagittal line to pleural 

tips by axial processes and sockets. 

Pygidial outline rounded subtriangular, length 

(sag.) three-fourths maximum width (trans.) ; dorsal exterior surface without trace of axis, smoothly 

convex in lateral and posterior view, lacking border 

or marginal rim. Doublure slightly concave dorsally, 

wide (sag.), extending under distal one-third of pygidium; outline of proximal margin broadly V-shaped 

in dorsal view. 

Holotype.-USNM 169623. 

Paratypes.-USNM 169621; 169622; 169624a, b. 

Occun·ence.-USGS colin. D1872 CO, Copenhagen 

Formation. Thirty feet below USGS coHn. D1880 CO, 

Copenhagen Formation.l\lR-U, upper member (member C of Merriam) Copenhagen Formation, Martin 

Ridge. USGS coHn. D1912 CO, upper 50 ft of Copenhagen Formation. 

Discussion.-Whittington (1954, p. 141-142) has 

discussed many of the species of A nataphrus present in the Middle and Upper Ordovician of North 

America. The characteristic serving to distinguish 

A. martinensis n. sp. from these species and from 

A. bromidensis (Esker) is the high eye lobe with a 

visual surface nearly encircling the lobe. Probably 

the closest species to A. martinensis n. sp. is A. 

vigilans Meek and Worthen, 1870, from the Maquoketa Shale in Illinois. A. spurius (Phleger) (Ross, 

1967a, p. D12) also possesses a smaller eye than 

A. martinensis. Additional collecting may provide 

some overlap between these two species. 

460-196 0-72-4 

Family NILEIDAE Angelin 1854 

Genus NILEUS Dalman, 1827 

Nileus? sp. 

Plate 4, figure 1 

A single partial cranidium may be assignable to 

Nileus, but in the absence of free cheeks, in particular, the assignment is questionable. In the absence of 

free cheeks and pygidium, a comparison at the species level is impossible. The cranidium is illustrated 

as a matter of record. 

Figured specimen.-USNM 169625. 

Occu1Tence.-Loc. SR-L, Copenhagen Formation. 

Family ILLAENIDAE Hawle and Corda, 1847 

Illaenid genus, indeterminate 

Two illaenid cranidia are included in collection 

MR-U. One of these is very large but badly damaged. 

The other is small and fairly well preserved but is 

lacking one palpebral lobe. A pygidium thought at 

first to belong to one of these has proved to be assignable to Anataphrus. Possibly the two cranidia belong 

to the same species and represent different growth 

stages. Poor preservation of the larger specimen prohibits complete comparison with the smaller. Therefore the two are described separately. 

Illaenid sp. 1 

Plate 4, figures 2, 3 

Cranidium decorticated, broken diagonally so that 

left, middle, and some of right posterior parts missing. Right palpebral lobe preserved. Right posterior 

fixed cheek crumpled beneath palpebral lobe. Anterior end of right axial furrow present, but none of 

left furrow preserved. Furrows seem to have been 

S-shaped and certainly were confined to posterior 

half of cranidium. Therefore, back of glabella missing, and any estimate of convexity largely conjectural. Right facial suture seems to run forward and 

downward straight for about 10 mm before curving 

evenly inward. Most of front of cranidium broken 

and frayed so that anterior configuration can be only 

crudely estimated. Circumferential sagittal length 

estimated at 60 mm. 

This specimen shows some similarities to N anillaenus. 

Figured specimen.-USNM 169626. 

Occurrence.-Collection MR-U, Copenhagen Formation, member C. 

Illaenid sp. 2 

Plate 4, figures 4, 5 

Small cranidium about 5.5 mm in sagittal circumferential length. Greatest width (trans.) estimated 

7.0 mm. Right palpebral lobe missing; width (trans.) 
22 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

in front of palpebral lobes 5.7 mm. Width of glabella 

at posterior margin 3.0 mm. Axial furrows converge 

for exsagittal distance of 1.5 mm so that glabella is 

2.0 mm wide; then axial furrows diverge and fade 

out .about 2.5 mm from posterior margin. 

As seen with glabella approximately horizontal, 

transverse convexity very slight. Sagittal convexity 

strong from back to defined front of glabella, decreasing only slightly toward front of cranidium. 

However, when glabella is approximately horizontal, 

front of cranidium slopes downward and backward 

so that anterior margin lies beneath glabella. 

Exsagittal length (diameter) of palpebral lobe 

about 1.0 mm. Facial suture runs straight forward 

and downward about 1.5 mm before curving inward 

to margin. No distinct border on cranidium, but three 

or four coarse terrace lines spaced 0.25 mm apart 

roughly parallel margin. 

Figured specimen.-USNM 169627. 

Occurrence.-Collection MR-U, Copenhagen Formation, member C. 

Discussion.-In the absence of any knowledge of 

the pygidi urn, this specimen would be extremely difficult to differentiate from many that are assigned to 

Illaemls. The glabella is narrow (trans.) for Bumastoides, and axial furrows are better developed than 

Whittington's (1954, p. 139) concept of that subgenus permits. Convexity of cranidium in lateral 

view is much like that of specimens of Illaenus auriculatus (Ross, 1967a, pl. 5, figs. 2, 4, 10) and other 

species. 

Family DIMEROPYGIDAE Hupe, 1953 

Genus TOERNQUISTIA Reed, 1896 

Toernquistia? idahoensis Churkin 

Plate 4, figures 6-9 

Toernquistia idahoensis Churkin, 1963, Jour. Paleontology, v. 

37, no. 2, p. 426-427, pl. 51, figs. 15-21. 

Figured specimens.-USNM 169628; AMNH 

29113-29115. 

Occurrence.-Caesar Canyon Limestone, loc. G K 

and USGS colin. D1914 CO. 

Discussion.-Churkin (1963, p. 427) noted that 

this species might be assigned to Chomatopyge Whittington and Evitt, rather than to Toernquistia, but 

the tapering glabellar outline and shallow furrows 

separating fixed cheeks from preglabellar field are 

typical of Toe1·nquistia. Reed (1904, p. 86-87, pl. 12, 

figs. 3-7) described from the Balclatchie beds of 

Ayrshire, Scotland, three cranidia that he assig-ned 

to Toe1·nquistia cf. T. nicholsoni. The Scottish specimens seem to have short (exsag.) palpebral lobes, 

shorter than those of T. nicholsoni from the Kiesley 

Limestone of England, of Churkin's Idaho specimens, 

or of ours from Nevada. 

Family HARPIDAE Hawle and Corda, 1847 

Harpid genus, indeterminate 

Plate 4, figure 10 

Figured specimen.-USNM 169629. 

Occurrence.-USGS colin. D249a CO, Copenhagen 

Formation, member C. 

D,iscussion.-This specimen is figured as a matter 

of record. The relatively wide (trans.) brim and 

small disordered pits present are typical of both Hibbertia Jones and Woodward and Pa1·aharpes Whittington. 

Family TRINUCLEIDAE Hawle and Corda, 1847 

Subfamily CRYPTOLITHINAE Angelin, 1854 

Genus CRYPTOLITHOIDES Whittington, 1941 

Since Whittington's original description, little 

additional material of Cryptolithoides has been discussed. Some emendations of the generic description 

are proposed here. Originally, the distinctive generic 

features were given as: Absence of reticulate ornament on cephalon, expanded anterolateral corners of 

fringe, fringe pits with rows E1 and I1 concentric 

and partly radially arranged, pits I2-I4 (I5 present 

anteriorly in some specimens) radially arranged anterior to glabella; pits of I2-I4 positions randomly 

scattered posterolaterally to glabella. Cryptolithus 

fittsi Ulrich and Whittington (in Whittington, 1941) 

was excluded because it lacked prominent anterolateral extensions of the fringe and had reticulate 

ornament on the glabella and cheeks. 

Reticulate ornament is probably a subsidiary characteristic for defining any trilobite genus, and much 

of the Nevada material possesses most of the above 

characteristics of Cryptolithoides as well as such 

ornament. The Nevada specimens (and, in fact, the 

original material of Cryptolithus fittsi) show numerous gradations between expanded anterolateral 

fringe margins and Cryptolithus-like fringe margins. 

To differentiate consistently between C1·yptolithus 

and Cryptolithoides, one is thus brought to details of 

the fringe. The adventitious pits and disordered 

arrangement of pits proximal to E1 and 11 are the 

main bases for distinguishing the two genera and 

are used here. 

In distinguishing between Cryptolithus and Cryp-

. tolithoides, primary emphasis is placed on interruptions in the radial arrangement of pits in the anterior 

part of the fringe. If obvious connections along radial 

lines are ,made in tracings of various cryptolithinids 

(fig. 3), the forms from Oklahoma and Nevada have 

far greater disorder than eastern representatives of 

Cryptolith us sensu stricto. The following forms thus 

are placed in Cryptolithoides: C. carinatus Whittington 1941; C. convexus Whittington 1941; C. fittsi 
A 

B 

FIGURE 3.- Line tracings of cryptolithinid genera and species from 

North America. Arrangement of radial pit rows emphasized to contrast the genera Cryptolithoides and Cryptolithus. A, Cryptolithoides 

sp.; lower part of Viola Limestone; west of Highway 77, about 15 

miles north of Ardmore, Okla. X 2.5. B, Cryptolitlws lorrettensis; 

Montmorency Falls, Quebec (after Whittington, 1968). X 11.3. 

C, Cryptolitlws tesselatus; Tribes Hill, N.Y. (after Whittington, 

1968). X 4.5. D, Cryptolith aides reticulatus n. sp.; upper member of 

Copenhagen Formation, USGS colln. D1880 CO. X 2.5. E, Cryptolithoides sp. Same as A. X 5.6. F, Same as D . . x 5.6. G, Same as D. 

X 6.8. H, Same as D. X 2.5. /, Same as D. X 2.5. J, Cryptolithoides 

reticulatus n. sp.; loc. 7106, X 2.5. K, Cryptolithoidcs rcticulatus 

n. sp.; USGS colln. D1880 CO, X 5.6. L, Cryptolithoides retic.ulat11s 

n. sp.; USGS colln. D1880 CO, X 2.5. J1.1, Cryptolithoides rcticulatus 

n. sp.; USGS colin. D1880 CO, X 5.6. 

~ 

ifJ 

::: 

/. 

'f., 

""' 

~ 

-3 

r'~ 

....... 

.-, 

-3 

~ 

'I'J). 

1:-..j 

~ 
24 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

Ulrich and Whittington, 1941; C. ulrichi Whittington; C. 'teticulatus n. sp. The first four of these have 

all been reported from Oklahoma. 

The first three of this group retain cephalic outlines similar to those of Cryptolithus and may well 

represent transitional forms between eastern species 

of Cryptolithus and members of Cryptolithoides with 

angulate margins and more pronounced pit disorders. 

Shaw has in progress a detailed stratigraphic study 

of Oklahoma cryptolithinids to clarify these relationships. 

Cryptolithoides as here defined is known only from 

the central and Western United States, probably 

from British Columbia (B.S. Norford, oral commun., 

1965) and from Yukon (Lenz and Churkin, 1966). 

Cryptolithus reportedly occurs with Cryptolithoides 

in the Viola Limestone of Oklahoma (Whittington, 1941) ; however, this report is based on only 

three cephala (Whittington, 1941, p. 37, pl. 6, fig. 15). 

Cryptolithus, to which Cryptolithoides obviously is 

closely related and from which it perhaps was derived, is common in rocks of Barneveld age of eastern 

North America (Whittington, 1968). The upper part 

of the Viola, member C of the Copenhagen, and Caesar Canyon Formations are probably Barneveld in 

age. 

Cryptolithoides fittsi (Ulrich and Whittington), 1941 

Plate 5, figures 18, 20, 21, 23 

Cryptolithus fittsi Ulrich and Whittington. Whittington, 1941, 

Jour. Paleontology, v. 15, no. 1, p. 36-37, pl. 5, figs. 

3, 5, 6, 10-12, 16, 20, 24. 

Two cranidia, one from member C of the Copenhagen Formation northeast of Segura Ranch (USGS 

colin. D1880 CO) and one from the Caesar Canyon 

Limestone at Caesar Canyon, probably assignable to 

this species. Cephalic outline semicircular, ratio of 

length (sag.) to width (max. trans.) about twofifths, glabellar outline expanding evenly anteriorly, 

maximum width (trans.) about five-sixths length; 

glabella slightly carinate, small median tubercle present. Occiput occupying posterior two-fifths of glabella, anterior end defined by 2p glabellar furrow ; 

1p furrow with small pit; occipital pit also present. 

Occipital ring not preserved. Cheek inflated, width 

(trans. opposite anterior end of occiput) equal to 

length (exsag.) along axial furrow. No eye ridge or 

eye lobe present. Anterior pit well developed. Surface 

of cheek and median area of glabella covered with 

reticulate raised lines. Arrangement of pits in fringe 

variable. One specimen from USGS colin. D1880 CO 

(pl. 5, fig. 21) shows only E1, I1, and I2, developed anterior to glabella with fair concentric and radial symmetry. At R5 an additional row is intercalated; this 

is maintained to about R17, where nearly complete 

disorder occurs in pit arrangement. E1 total 28 pits 

(one side). Distinctive feature of this specimen is 

presence of only three concentric rows of pits on 

anterior part of fringe. Specimen from Caesar Canyon has four well-developed concentric rows anterior 

to glabella and approximately same pit pattern as 

described above lateral to this. Whether this indicates a different species or intra-specific variation 

cannot be told from few specimens available. 

Figured specimens.-USNM 169634, 169635. 

Occurrence.-USGS colin. D1880 CO, Copenhagen 

Formation, top 100ft; loc. CC, Caesar Canyon Limestone. This species previously reported by Whittington (1941, p. 37) from the Viola Limestone of 

Oklahoma and Pete Hanson Creek, Roberts Mountains, Nev. (Hanson Creek Formation). 

Discussion.-The assignment of this species to 

Cryptolithoides has been discussed above. C. fittsi 

differs from C. reticulatus n. sp. in having a more 

semicircular cranidial outline, longer ( exsag.) cheek 

areas, and fewer rows of pits anterior to the glabella 

and in row El. Differences from Oklahoma species 

such as C. carinatus Whittington and C. convexus 

Whittington are less well defined, being chiefly the 

larger number of pits in row E1 of C. fittsi. 

Cryptolithoides reticulatus n. sp. 

Plate 4, figures 11-19; plate 5, figures 1-17, 19 

This description is based on the following specimens: 18 cranidia from USGS colin. D1880 CO and 

four from Caesar Canyon ( loc. CC) , three pygidia 

from collection 01880 CO and five from Caesar Canyon ( loc. CC) , and partial specimens from these collections and USGS collns. D1901 CO and D1914 CO. 

Cephalic outline nearly semicircular, length (sag.) 

slightly less than one-third width (max. trans. at 

anterolateral margin) ; anterolateral margin laterally expanded as in C. ul1·ichi Whittington. Glabella 

slightly carinate, expanding evenly anteriorly; median tubercle present at one-half length (sag.) ; 

maximum width (trans.) of glabella just posterior 

to anterior pits and equal to about one-fourth total 

cephalic width (trans.) at this point. Occiput not 

clearly defined; only one glabellar furrow clearly 

observed, and this accomplishes typical posterior constriction of glabella at posterior end; well-developed 

pit developed on lateral slope of this posterior bulge. 

Occipital ring very short (sag.), median part broken 

on all specimens. Cheeks more triangular in outline 

than in C. fittsi, width (trans. at widest point) 

slightly greater than length ( exsag. along axial furrow) ; surface of cheek covered with reticulate ornament but (in larger holaspids) does not show eye 

ridges or eye lobes (pl. 5, fig. 4). 
DESCRIPTIONS OF TRILOBITES 25 

Pits E1 and !1 concentrically and radially arranged; E1 pits separated by prominent radial ridges 

average about 30 (one side). Four to five concentric 

rows of pits present anterior to glabella in all specimens; radial arrangement holding laterally to about 

E7 in larger individuals, farther around fringe in 

smaller specimens. Adventitious pits irregularly 

present even in front of glabella in some specimens. 

Vestiges of radial arrangement preserved as far as 

E20 in some specimens; these rows may have as 

many as eight pits; concentric and radial arrangement totally lacking posterior to this point. Lower 

fringe shows only one row of pits exterior to girder 

and long genal spine directed posterolaterally. 

Pygidial outline subtriangular, length (sag.) 

slightly more than one-fourth of width (trans. rnax. 

anterior) . Axial width (trans. anterior) about oneseventh total pygidial width (trans. anterior) , axis 

tapering evenly posteriorly to rim of pleural field; 

nine to 11 axial rings visible; distal ends of axial 

ring furrow directed slightly posterolaterally. Average of seven pleural furrows cross pleural field, distal 

ends flexed posterolaterally. 

Holotype.-USNM 169630. 

Pa1·atypes.-USNM 169631a-m; 169632a, b; 

169633. 

Occurrence.-USGS colln. D1880 CO, Copenhagen 

Formation. USGS colin. D1901 CO, Caesar Canyon 

Limestone, Mill Canyon sequence. USGS collns. 

D1914 CO and D1915 CO, Caesar Canyon Li:mestone, August Canyon sequence. Loc. CC, CaE~sar 

Canyon Limestone, August Canyon sequence. 

Discussion.-From the shape of the anterolateral 

parts of the fringe and the general size and disarray 

of the fringe pits, this species is evidently assignable 

to Cryptolithoides. The presence of four to five eoncentric rows of pits anterior to the glabella combined 

with the reticulate ornamentation on the cheek8 of 

most specimens separate this species from C. fiUsi. 

Two cranidia from USGS colin. D1880 CO (for 

example, pl. 5, fig. 14) show four to five concentric 

rows of pits anterior to the glabella and obviously 

belong to this species. They display eye ridges at 

about the midlength of the glabella and small eye 

lobes set close to the axial furrow. Small lenticular 

alae also extend along the side of the glabella anteriorly from the occipital furrow to the eye ridge. 

Family RAPHIOPHORIDAE Angelin, 1854 

Genus LONCHODOMAS Angelin, 1854 

Lonchodomas sp. 

Plate 6, figures 1-3 

Cranidium from USGS colin. D1913 CO somewhat 

similar to that of L. halli (Billings) from eastern 

North America (see Shaw, 1968, p. 36-37, pl. 5, figs. 

17-19, 23, 24, 31) in having a short (sag.) glabella 

tapering abruptly into anterior spine, maximum glabella width at three-fifths sagittal length. Anterior 

part of fixed cheek a flat, shelflike border. 

Figured specimens.-USNM 169636, 169637. 

Occurrence.-USGS collns. D1913 CO and D249a 

CO, Copenhagen Formation, member C. 

Discussion.-The anterior part of the fixed cheek 

is like that of L. halli and L. normalis (Billings). 

(See Whittington, 1965, pl. 10, fig. 14.) The glabellar 

width to length ratio, however, appears to fall between the ratios in these two species. L. 'retrolatus 

Ross, 1967, from the Eureka Quartzite at the Nevada 

Test Site, differs from the above species in its exceptionally short (sag.), broad glabella. 

The specimen from collection D249a (pl. 6, figs. 

1, 2) is essentially similar to the one from D1913 CO 

except that it has an exceptionally thick ( dorsoventral) anterior spine. Until additional specimens can 

be found with this thick spine, this feature cannot 

be utilized as a specific characteristic. 

Genus AMPYXINA Ulrich, 1922 

Ampyxina salmoni Churkin 

Plate 6, figures 4-10 

Ampyxina salmoni Churkin, 1963, Jour. Paleontology, v. 37, 

no. 2, p. 424-425, pl. 51, figs. 1-10. 

Figu1·ed specimens.-USNM 169638; 169639a, b. 

AMNH 29116, 29117, 29120, 29121. 

Occu1·rence.-Caesar Canyon Limestone, USGS 

collns. D1914 CO and D1916 CO, loc. GK. Previously 

described from Saturday Mountain Formation of 

Idaho (Churkin, 1963). 

Discussion.-Two excellent complete specimens 

from the Caesar Canyon Limestone at locality GK 

("Gatecliff") show the five segments typical of the 

genus. The free cheeks curve posteriorly to parallel 

the axis and project posterior to the rest of the 

exoskeleton. Churkin envisaged straight (trans.) or 

anteriorly recurved pygidial pleural ribs as distinctive for this species. This characteristic appears quite 

variable so that at least one specimen (pl. 6, fig. 6) 

closely resembles A. powelli (Raymond) from the 

Edinburg Formation of Virginia. Other described 

species of Ampyxina (Whittington, 1959) differ in 

having a stronger posterior curve to the pleural 

pygidial furrows and a longer (sag.) and narrower 

(trans.) glabella and (or) an anterior glabellar spine. 

Genus RAYMONDELLA Reed, 1935 

Raymondella nevadensis n. sp. 

Plate 6, figures 11-13, 15, 17 

Only cranidia and pygidia are known. Cranidial 
26 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

outline rounded triangular; length (sag.) one-half 

maximum transverse width at posterior border. Glabella ovoid. in dorsal view, width (trans.) to length 

(sag.) ratio seven-ninths; maximum width (trans.) 

of glabella two-thirds sagittal distance anterior to 

occipital furrow; low, rounded keel developed on 

sagittal line of glabella. Small anterior spine on small 

specimen, none on large. At its posterior end, each 

side of glabella sharply indented anterior to occipital 

furrow; alae low and inconspicuous, paralleling divergent posterolateral sides of glabella for about onethird glabellar length (sag.). Fixed cheeks almost 

diamond shaped, rising steeply from axial and border furrows .. Posterior cranidial border relatively 

long (exsag.) for the genus, length (exsag.) about 

one-sixth width (trans.). Occipital ring shorter 

(sag.) than border, not well shown on available 

material. Fixed cheeks bear raised line ornament 

typical of the genus. 

Pygidium transversely semielliptical in dorsal 

view, length (sag.) 0.23-0.3 width (max., trans. at 

anterior end). Width of axis (trans. ant.) about 0.2 

total pygidial width; tapering posteriorly to rim of 

pleural field; five axial rings; distal ends of rings 

with slight posterior curve. Three straight pleural 

furrows cross flat pleural field diagonally to rim. 

Pygidial border distal to rim forms nearly vertical 

face. No ornament visible on available pygidial material. 

Holotype.-USNM 169640. 

Paratypes.-USNM 169641a, b; 169642a, b. 

Occurrence.-Caesar Canyon Limestone, USGS 

colin. D1914 CO. Copenhagen Formation, USGS 

colin. D1880 CO. 

Discussion.-R. elegans (Cooper, 1953) previously 

was the only well-known North American representative of this genus. The present species is differentiated on the basis of total lack of an anterior glabellar 

spine in large specimens and the presence of at least 

four axial rings (rather than three) in the pygidium. As most of the Nevada specimens available 

are somewhat larger than those figured by Whittington (1959) and Cooper (1953), and their specimens 

show a gradual reduction in the anterior glabellar 

spine with increasing size, additional Nevada material conceivably might show the two species to be 

synonymous. 

Raymondella Reed was based on R. maconachiei 

from the Balclatchie beds, Girvan District, Scotland. 

This genus, like Toernquistia, may indicate a link 

with southwest Scotland as well as with the Appalachians. 

Family CHEIRURIDAE Salter, 1864 

Genus CERAURINELLA Cooper, 1953 

Ceraurinella sp. 

Plate 6, figure 14 

This description is based on a single cranidium. 

Cranidiallength (sag.) equal to width (trans.) along 

a line across glabellar lobe 1p. Posterior end of 

glabella occupies 0.34 total cranidial width. Glabellar outline expands anteriorly; maximum width 

(trans.), anterior to furrow 3p, 1.18 times width 

across lobes 1p. Glabella furrows 1p, 2p, and 3p 

evenly spaced and of equal width (trans.), furrow 

3p at about 0.6 total glabellar length. Lobe 1p set 

off from remainder of glabella by slightly indented 

longitudinal furrow. Fixed cheek evenly convex; eye 

lobe opposite furrow 2p; distance from outer edge 

of palpebral lobe to axial furrow equal to 0.5 glabellar width (trans.) at this point. 

Posterior border furrow and occipital furrow well 

incised. Surface of cranidium uniformly covered with 

fine tubercles. 

Figured specimen.-USNM 169643. 

OccuJTence.-Copenhagen Formation, USGS colin. 

D1880 CO. 

Discussion.-The left genal angle of this small 

specimen cannot be further prepared without destroying one of the paratypes of Anataphrus martinensis. A genal spine seems to be present, but its 

size and shape cannot be determined. 

Genus CERAURUS Green, 1832 

Ceraurus? sp. 

Plate 6, figure 18 

Only a badly preserved internal mold of a cranidi urn is the basis for this description. Frontal lobe of 

glabella incomplete; therefore glabellar proportions 

cannot be determined. Lateral glabellar lobes of equal 

length (exsag.) and width (trans.). Lobe 1p virtually isolated by furrow 1p curving backward to 

occipital furrow. Fixed cheeks poorly preserved. 

Position of right palpebral lobe indicated by furrow 

to be opposite glabellar lobe 2p. Occipital and posterior border furrows well incised. Surface of glabella covered with coarse tubercles. 

Figured specimen.-USNM 169645. 

Occurrence.-USGS colin. D1860 CO, Copenhagen 

Formation, Hot Creek Canyon. 

Discussion.-This specimen is so poorly preserved 

that it cannot be identified with certainty as to genus. 

Coarse pustules on the glabella seem to favor Ceyaurus, but position and shape of the eye in the 

opinion of Ross suggest that this specimen may be a 

cybelid. 
DESCRIPTIONS OF TRILOBITES 27 

Chdrurinid genus, indeterminate 

Plate 6, figure 16 

A large fragment of the cranidium of a cheirurid 

trilobite shows part of the glabella, a small part of a 

fixed cheek, and the palpebral lobe. It is illustrated 

here as a matter of record. 

Figured specimen.-USNM 169644. 

Occurrence.-USGS colin. D1876 CO, Copenhagen 

Formation, member C. 

Discussion.-Shaw comments that this specirnen 

is most like Hapsiceraurus Whittington but differs 

from previously described species in the extreme 

anterolateral location of the eye lobe and peculiar 

arcuate tubercle arrangement on the anterior part 

of the glabella. The glabellar and free cheek ornament closely resembles that of Pa1·acerau1·us yuedemanni (Raymond). (See Shaw, 1968, pl. 16, :figs. 

1, 2, 5-8.) 

Genus SPHAEROCORYPHE Angelin, 1854 

Sphaerocoryphe sp. 

Plate 7, figures 1, 2 

A specimen, an anterior cranidial bulb, in spite 

being only a fragment, appears assignable to Sphae1'ocoryphe. Characteristic features are the roundness 

in dorsal and lateral views, the character of the 

pustulose ornament, and the presence of part of the 

smooth, shallow axial furrow along the left side of 

the bulb. It is illustrated as a matter of record. 

Figu1·ed specimen.-USNM 169647. 

Occut'r'ence.-USGS colin. D1874 CO, Copenhagen 

Formation. 

Discuss,ion.-Ross (1967, p. D23) has recorded 

pygidia from the Antelope Valley Limestone near 

Pyramid Peak, Calif., which may belong to this 

genus. Sphaerocm·yp'he has a long stratigraphic range 

(Middle and Upper Ordovician) and is known from 

much of northern Europe and North America. 

Family ENCRINURIDAE Angelin, 1854 

Genus CYBELOIDES Slocum, 1913 

Cybeloides Slocum. Shaw, 1968, New York State Mus. and 

Sci. Serv. Mem. 17, p. 66. 

Cybeloides sp. 

Plate 6, figure 19 

Figut·ed specimen.-USNM 169646. 

Occun·ence.-USGS colin. D1874 CO, Copenhagen 

Formation, member C. 

Discussion.-This immature specimen is similar to 

pygidia described by Shaw (1968, p. 68, pl. 9, figs. 

12, 17, 19, 20; pl. 10, fig. 7) and Cooper (1953, p. 

31-32, pl. 13, figs. 6, 8, 11, 20). The major difference 

lies in the posteriorly poorly defined pleural ribs and 

a large post-axial field occupied by shallow pits. 

C. pTima (Raymond) shows these same characteristics to a lesser degree. C. virginiensis Cooper displays 

a very small, unpitted post-axial area. 

The genus has a wide stratigraphic and geographic 

range, being known from the Middle and Upper 

Ordovician of North America and Europe. 

Family CAL YMENIDAE Burmeister, 1843 

Calymenid genus, indeterminate 

Plate 7, figures 3-8 

Figured specim,ens.-AMNH 29122-29125, USNM 

169648, 169660. 

Occurrence.-Caesar Canyon Limestone, USGS 

colin. D1914 CO and loc. GK. Saturday Mountain 

Formation, Bayhorse district, Idaho, USGS colin. 

D1916 CO. 

Discussion.-The Caesar Canyon Limestone has 

yielded five specimens originally identified by Churkin (1963) as Fle::dcalymene sp. Generic identification of calymenids rests largely on details of the 

cephalon which are not available on this material. 

In addition, the very different characteristics of the 

anterior border and the glabellar outline in the two 

cranidia suggest that the cranidia have been badly 

deformed. The pygidia are relatively well preserved 

and differ from those of most other calymenids in 

having a length (sag.) to width (trans., anterior 

end) ratio of one-half. Six axial rings and five posteriorly curving pleural ribs set off by deep pleural 

furrows are visible; faint interpleural furrows are 

visible distally on ribs. These are the first described 

calymenids from upper Middle Ordovician formations of central Nevada. 

A pygidium from the Saturday Mountain Formation of Idaho (USGS colin. D1916 CO) is somewhat 

more convex than any of the Caesar Canyon specimens and has a more robust axis. 

Dr. W. T. Dean (oral commun., Aug. 8, 1970) 

has suggested that the cranidium illustrated in figure 

6 of plate 7 might be assigned to Platycoryphe. 

Although this possibility warrants consideration, we 

lack enough well-preserved specimens to confirm it. 

Family PTERYGOMETOPIDAE Reed, 1905 

Genus CALYPTAULAX G. A. Cooper, 1930 

Calyptaulax Cooper, 1930, Am. Jour. Sci., ser. 5, v. 20, p. 

386-388. 

Calliops Delo, 1935, Jour. Paleontology, v. 9, no. 5, p. 417-418. 

Calyptaulax Cooper. Whittington, 1965, Harvard Univ. Mus. 

Camp. Zoology Bull., v. 132, no. 4, p. 430-431. 

Calyptaulax Cooper. Shaw, 1968, New York State Mus. and 

Sci. Service Mem. 17, p. 83-84. 
28 MIDDLE ORDOVICIAN COPENHAGEN FORMATION AND ITS TRILOBITES 

Calyptaulax cf. C. callirachis (B. N. Cooper) 

Plate 7, figures 9-15 

Cranidial length (sag.) to width (trans.) ratio 

0.66. Anterior end of glabella and glabellar furrows 

damaged and largely obscured. Glabellar lobe lp 

very small, completely detached from glabella; furrows and lobes 2p and 3p difficult to make out 

furrow 3p seems to start opposite anterior end of 

palpebral lobe. Palpebral lobe length ( exsag.) 0.66 

cranidiallength (sag.) ; palpebral rim wide (trans.), 

semicircular in outline; posterior end opposite occipital ring. Occipital ring length (sag.) 0.45 width 

(trans.), ring outline subtrapezoidal in dorsal view. 

Visual surface of eye curved, height in lateral view 

about half total cranidial height; facets arranged in 

vertical rows, as typical for the genus, about 125 

facets present in each eye. Lateral and posterior 

cranidial borders wide; genal angle pointed, but 

seemingly not bearing a spine. 

Pygidial outline subtriangular; length (sag.) 0.66 

width (max. trans.) at anterior end; axis width 

(trans.) about 0.25 total pygidial width at anterior 

end, axis tapering gradually posteriorly, ending at 

0.75 pygidial length (sag.) ; about eight axial rings 

present, articulating half-ring prominent and about 

same shape as axial rings. Axis semicircular in cross 

section, standing above pleural field; pleural field 

inflated, crossed by approximately seven pleural furrows. Interpleural furrows present on distal half of 

pleural field. Cranidial and pygidial surfaces pustulose. 

Figuredspecimens.-USNM 169649a-c ;169650a, b. 

Occurrence.-Copenhagen Formation, locs. MR 

and SR; USGS collns. D286 CO and D1880 CO. 

Discussion.-These specimens appear distinct in 

having very long (exsag.) palpebral lobes and eye 

lobes. They most closely resemble C. callirachis 

(Cooper, 1953, pl. 18, figs. 1-4, 8) in glabellar, cranidial, and pygidial outline. They appear to differ 

from C. cornwalli Ross (1967a, p. 29, pl. 8, figs. 

28-33) in possessing a relatively longer glabella. 

C. callirachis is known from the Edinburg and 

Athens Formations of the Appalachians (Cooper, 

1953, p. 39) and thus is probably about the same 

age as most of the Nevada material. 

Family LICHIDAE Hawle and Corda, 1847 

Genus AMPHILICHAS Raymond, 1905 

Amphilichas aff. A. minganensis (Billings) 

Plate 7, figures 16-20, 23 

Figured specimens.-USNM 169651a, b; 169652. 

Occurrence.-Copenhagen Formation, USGS 

collns. D187 4 CO, D249a CO. 

Discussion.-This species is very similar to A. 

minganensis (Billings) (Shaw, 1968, p. 89-94, pl. 3, 

figs. 2-25; pl. 4, fig. 1). The major difference between 

the two species is the narrower (trans.) median lobe 

in the Nevada species; however, variation in A. 

minganensis as shown by a cranidium with narrow 

median lobe (Shaw, 1968, pl. 3, fig. 9) may include 

the Nevada form. The Nevada cranidium closely resembles that of A. dalecarlicus Angelin (Warburg, 

1925, pl. 7, fig. 24). 

The hypostome has a markedly indented posterior 

border, the border itself bearing widely spaced terrace lines subparallel to the margin. The median 

body bears tubercles, with no trace of the prominent 

pits shown in one small specimen of A. minganensis 

(Shaw, 1968, pl. 3, fig. 8) ; the Nevada hypostome is 

very similar to a larger specimen illustrated by Shaw 

( 1968, pl. 3, fig. 12). 

The pygidium shows the proximal part of the right 

pleural field only and evidently belongs to the same 

genus, with no pleural furrow present on the third 

pleural lobe. In the absence of well-preserved pygidia 

and a graded size series of cranidia, no specific assignment of these specimens can be made. 

Family ODONTOPLEURIDAE Burmeister, 1843 

Genus MIRASPIS R. and E. Richter, 1917 

Miraspis sp. 

Plate 7, figures 21, 22 

P~·imaspis sp. (part), Churkin, 1963, Jour. Paleontology, v. 

37, no. 2, pl. 51, fig. 13 only. 

Cranidial width (trans.) to length (sag.) ratio 

four-thirds, width (trans.) of median lobe 0.25 total 

cranidial width. Length of glabellar lobe lp nearly 

half total cranidiallength, lobe 2p 0.5 length of lobe 

lp and same width. Lobes lp and 2p separated by 

diagonal furrow. Lobe 3p very small, nearly circular 

in outline, and set off from median and other glabellar lobes by deep furrows. Occipital ring longest 

sagittally, possessing median tubercle and two posteriorly directed spines. Spine length nearly equal to 

cranidial length. Anterior and lateral cranidial structures not preserved. 

Figu'red specimens.-USNM 169653a, b. 

Occu1·rence.-Upper part Caesar Canyon Limestone at Caesar Canyon, USGS colin. D1915 CO. 

Discussion.-Only two cranidia of this species 

were found. They and the one specimen illustrated 

by Churkin (1963, pl. 51, fig. 13) are the only specimens of Miraspis known from either the Nevada or 

the Idaho locality. 

Except for the well-developed occipital spines, 

these specimens closely resemble those assigned to 

Primaspis elsewhere in this paper. Judged from recent descriptions by Whittington and Bohlin (1958) 

and Bruton (1965, 1966), the occipital spines of 
REFERENCES CITED 29 

Miraspis are the only cranidial features distinctive 

from Primaspis. 

Genus PRIMASPIS R. and E. Richter, 1917 

Primaspis churkini n. sp. 

Plate 8, figures 1-10 

Primaspis sp. Churkin, 1963, Jour. Paleontology, v. 37, no. 2, 

p. 425-426, pl. 51, figs. 11, 12, 14. 

In his description of Primaspis sp., Churkin (1H63, 

p. 425, pl. 51, fig. 13) included a cranidium with 

paired spines on the occipital ring; we have reassigned this specimen to Miraspis sp. Therefore, 

except for the reference to "a pair of small spines" 

on the occipital ring, Churkin's (1963, p. 425-426) 

description is used for this new species with the following emendation: Anterior part of glabella merges 

with anterior cephalic border; border furrow seemingly absent in front of glabella. Small median tubercle on occipital ring. On pygidium as many as six 

pairs of secondary spines present outside long primary pair. 

Holotype.-USNM 169654. 

Paratypes.-USNM 169655a-e, 169656; AMNH 

29126-29128. 

Occurrence.-Saturday Mountain Formation, 

Idaho, USGS colin. D1916 CO. Caesar Canyon Limestone, Nevada, loc. GK and USGS colin. D1914 CO. 

Discussion.-Churkin's (1963, p. 425-426) description was based on specimens from the Saturday 

Mountain Formation. Ten cranidia and two pygidia 

are topotypic paratypes in USGS colin. D1916 CO. 

Two pygidia and a single free cheek from the Caesar 

Canyon Limestone at locality GK ("Gatecliff") comprise the material mentioned by Churkin (1963, p. 

426). 

This species most closely resembles P. harnagensis 

(Bancroft) (Dean, 1960-63) but carries one to two 

additional marginal spines anterior to the prirnary 

pygidial spine. The species discussed by Whittington 

(1956) and Bruton (1965, 1966) differ either in having more secondary spines posterior to the prirr.tary 

pygidial spine or in having one of the secondary 

spines partially fused with the primary spine. 

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30 MIDDLE ORDOVICIAN COPENHAG,EN FORMATION AND ITS TRILOBITES 

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pls. 1-3. 
A Page 

Abstract .............................................................. 1 

Acodus auritus .................................................. 7 

sp .................................................................. 7 

Acontiodus alveolaris ...................................... 6 

sp .................................................................. 7 

Age, Copenhagen Formation and 

equivalents .................................. 11 

trilobites ........................................................ 10 

Albany Mudstone .............................................. 15 

alternata, Eoplectodonta ................................ 4 

alveolaris, Acontiodus ...................................... 6 

Amphilichas ...................................................... :es 

dalecarlicus ................................................ 28 

minganensis .................. 4, 5, 10, 28, :es; pl. 7 

Amplexoporid .................................................... 6 

Ampyx sp .......................................................... 9 

Ampyxina ............... .......................................... :!5 

powelli ........................................................ 25 

salmoni .......................................... 16, :!5; pl. 6 

Anataphrus .................................. 10, 12, 19, 20, 21 

borraeus ...................................................... 20 

bromidensis .............................................. 20, 21 

martinensis ................ 3, 4, 7, 10, :eo, 26; pl. 3 

spurius .................................................. 8, 20, 21 

vigilans .................................................... 20, 21 

sp .................................................................. 5 

anceps, Dicellograptus .................................... 16 

Anolotichia sp .................................................. 5, 6 

A nomalorthis oklahomensis .......................... 7 

Antelope Range .................................. 1, 3, 5, 6, 10 

Antelope Valley .............................. 1, 3, 10, 11, 12 

fossils from east side of Martin Ridge 5 

fossils from hill 8308 .............................. 3 

stratigraphic section .............................. 3 

Antelope Valley Limestone .......................... 1, 

3, 5, 6, 7, 9, 10, 20 

Arline Formation .......................................... 10, 11 

Asaphid .............................................................. 5 

Asaphidae .......................................................... 18 

Athens Formation ............................................ 28 

August Canyon sequence .............................. 9 

auriculatus, Illaenus ........................................ 22 

auritus, Acodus ................................................ 7 

Ayrshire, Scotland ........................................ 15, 22 

B 

Baffin Island ...................................................... 20 

Balclatchie beds .............................................. 22, 26 

barbara, Trichonodella .................................. 6 

Barrel Spring Formation .............................. 9, 20 

bearsi, Vogdesia .............................................. 20 

Belted Peak ........................................................ 5 

Belted Peak area, stratigraphic section .... 8 

Belodina monitorensis .................................... 6 

ornata .......................................................... 8 

Benbolt Formation .......................................... 5 

Berdan, Jean, quoted ...................................... 6, 7 

Berry, W. B. N., fossil identification ........ 11 

Bilobia sp .......................................................... 4 

Bimuria .............................................................. 9 

sp ·································································· 4 

zone .............................................................. 5 

bipartitus, Ottoseetaxis .................................. 5 

bivia, Eoleperditia .................................... 7 

r, 

INDEX 

[Italic page numbers indicate major references] 

Page 

Boardman, R. S., quoted ................................ 5 

borraeus, Anataphrus .................................... 20 

Brachiopods ....................................................... 1, 11 

Antelope VaHey ........................................ 3 

hill 8308 ............................................... J 

Belted Peak area ...................................... 8 

Clear Creek Canyon ................................ 6 

Independence Mountains ...................... 9, 10 

member C .................................................. 10 

breviceps, Goniophrys .................................... 14 

brevis, Eofalodus .............................................. 7 

British Columbia .............................................. 24 

Bromide Formation ............................ 6, 10, 11, 20 

Mountain Lake Member ........................ 4 

bromidensis, Anataphrus ···························~ 20, 21 

Homotelus ................................................... 20 

Bryozoans ......... ................................................. 11 

Antelope Valley, hill 8308 ............... :.... 4 

Belted Peak area ...................................... 8 

Clear Creek Canyon .............................. 6 

Bumastoides ...................................................... 22 

Burns Creek sequence .................................... 9 

c 

caecigenus, Triarthrus .................................. 14 

Caesar Canyon Limestone ................ 9, 10, 11, 16 

age of trilobite fauna .............................. 10 

Calliops .............. ............................................... 27 

callirachis, Calypt'aulax ........ 4, 5, 6, 10, :!8; pl. 7 

Calymenid genus, indeterminate ......... :!7; pl. 7 

Calymenidae ...................................................... :!7 

Calyptaulax ........................................................ :!7 

callirachis ........................ 4, 5, 6, 10, :!8 ; pl. 7 

cornwalli .................................................... 28 

strasburgensi8 .......................................... 9 

sp . . ... ........ .......................... ........ ......... 4, 7 

carinatus, Cryptolithoides .............................. 22 

Cryptolithus .............................................. 24 

Carrickia ............................................................ 14 

pelagia .......... ............................................. 14 

setoni ........................................................ 14, 15 

sp ....................................................... 7, 14; pl. 1 

Cephalopodes, Antelope Valley, hill 8308.... 4 

Ceraurinid .......................................................... 4 

Ceraurinella ................................................... 10, :!6 

sp ·······'··············································· 3, :!6; pl. 6 

Ceraurus ............................................................ :!6 

sp ...................................................... 7, :!6; pl. 6 

Chazy Group ...................................................... 20 

Chazydictya ........................................................ 5 

chazyensis .................. ................................ 4 

sp ·································································· 4 

ch.a.zyensis, Ch.azudictya ................................ 4 

Chazy Limestone, New York ..................... . 

Cheiruridae ........................................................ :!6 

Cheirurinid genus, indeterminate ........ :!7; pl. 6 

Chomatopy.cJe .................................................... 22 

churkini, Primaspis ................................ :!9; pl. 8 

Clear Creek Canyon ........................................ 5 

correlation oJ' fossils ............................. . 

stratigraphic section ............................. . 

Climarograptus hastatus ............................... . 

ph yllophorus ............................................. . 

typicalis ..................................................... . 

sp .. ······························································· 

7 

6 

10 

4 

11 

11 

Page 

Collections and localities ................................ 1:! 

Conodonts ................................................ 1, 7, 11; 12 

Belted Peak area ...................................... 8 

Clear Creek Canyon ................................ 6 

Constellaria sp .................................................. 5 

contractus, Oistodus ........................................ 7 

convexus, Cryptolith.oides .............................. 22 

Cryptolithus .............................................. 24 

copenhagenensis, lsotelus .... 4, 5, 6, 10; pis. 2, 3 

Cordylodus sp .................................................... 8 

cornwalli, Calyptaulax .................................... 28 

Correlation, Copenhagen Formation 

and equivalents ........................ 10 

fossils at Clear Creek Canyon ............ 7 

costatus, Tetraprioniodus .............................. 7 

crassus, Desmorthis ........................................ 7 

cristifera, Cristiferina .................................... 4 

Cristiferina cristifera ................................... ·. 4 

sp .................................................................. 4 

Cryptolithid ...................................................... 6 

Cryptolithinae .................................................. :e:e 

Cryptolithoides .................. 9, 10, 11, 12, 15, 1!2, 24 

carinatus .................................................... 22 

convexus ...................................................... 22 

fittsi .................................................. 3, 24; pl. 5 

reticulatus .......................... 3, 23, 24 ; pls. 4, 5 

ulrichi .......................................................... 24 

sp ............................................ 4, 9, 16, 23; pl. 5 

zone .............................................................. 5 

Cryptolithus .................................................... 10, 24 

carinatus .................................................... 24 

convexus .................................................... 24 

fittsi .... ..................................................... 22, 24 

lorrettensis ................................................ 23 

tesselatus ................................................... . 

Cryptophyllus sp ............................................. . 

crystalluria, Phyllodictya ............................. . 

Cybeloides ......................................................... . 

prima 

virginiensis 

23 

6 

5 

27 

27 

27 

sp ...................................................... 4, :!7; pl. 6 

Cyrtoniodus flexuosus .................................... 6 

D 

dalecarlicus, Amphilich.as .............................. 28 

deckeri, Robergia ............................ 3, 16, 17; pl. 1 

Decorah Formation .......................................... 6 

Desmorthis crassus .......................................... 7 

Dicellograptus anceps .................................... 16 

Dichognathus .................................................... 7, 8 

typica .......................................................... 6 

sp .................................................................. 6 

Dimeropygidae .................................................. :!2 

Diplograptus sp ................................................ 11 

Diplotrypids ...................................................... 8 

Distacodus symmetricus .................................. 7 

sp .................................................................. 6, 8 

Drepanodus suberectus .................................. 6, 7 

sp .............. ................................................... 8 

E 

Edinburg Formation ........................ 10, 11, 16, 28 

Effna Formation .............................................. 11 

elegans, Raymondella ...................................... 26 

Encrinuridae :!7 

31 
32 

Page 

Encrinuroides sp ---------------------------------------------- pl. 8 

England ------------------------------------------------------------ 14, 22 

Eofalodus brevis ---------------------------------------------- 7 

Eojletcheria sp -------------------------------------------------- 9 

Eoleperditia bivia -------------------------------------------- 7 

Eoplectodonta alternata ·------------------------------- 4 

Eureka Quartzite ---------------------- 1, 3, 5, 7, 9, 12, 20 

Independence Mountains ------------------------ 9 

eximius, Remopleurides -------·-------------------------- 17 

F, G 

Faults --------·-------------------------.-------------------------------- 3 

jittsi, Cryptolithoides -------------·------------ 3, 24 ; pL 5 

Cryptolithus -------------------·------------------------ 22, 24 

Flexicalymene sp ---------------------------------------------- 27 

flexuosus, Cyrtoniodus ---·-------------------------------- 6 

Galena Dolomite 12 

gigas, Isotelus -------·---------------------------·-------------- 19 

Girvan District, Ayrshire, Scotland ........ 15, 26 

Glyptorthis sp -----------------·------------------·-------------

Goniophrys breviceps -----------------------------------·-· 

9 

14 

prima --------------------------------------------····--·-······ 14 

Graptolites -----------·----------·--------------------------- 9, 12, 16 

Antelope Valley, hill 8308 ---------------------- 4 

Caesar Canyon Limestone -------------------- 11 

member C -------------------·····-------------------------- 10 

Toquima Range 9 

H 

haUi, Lonchodomas ---------------------------------·-······· 25 

Hanson Creek Formation .............. 10, 12, 20, 24 

Hapsiceraurus --------------------·---------------------·------- 27 

harnagensis, Primaspis ----------------------·-------···· 29 

Harpid -------------------------------------·-------------------·------ 5 

Harpid genus, indeterminate ................ 22; pl. 4 

Harpidae --------·----------·--------------··················-------- 22 

harrisi, Isotelus ------------------------------------------------ 19 

hastatus, Climacograptus .............................. 10 

Hesperorthis sp ................................................ 4 

heteropleura, Laticrura .................................. 9 

Hibertia ------------------------------------------·------------------· 22 

Homotelus ____ --------·-----------------------------------------· 19, 20 

bromidensis ................................................ 20 

ulrich i ........... _____ .. ........................................ 20 

Homotrypid ---------------------·----------------------------------

Hope Shales ...................................................... 14 

Horse Heaven Mountain quadrangle ...... 1, 3, 6 

Hot Creek Canyon .......................................... 9 

stratigraphic section ------------------------------ 7 

Huddle, J. W., fossil identifications .......... 6, 7 

Huddle, J. W., quoted .................................. 6, 7, 8 

Hyperchilarina .................................................. 7 

sp .................................................................. 6 

Hypodicranotus .............. 3, 4, 10, 15, 15, 17; pl. 1 

missouriensis .............................................. 15 

striatulus -------------------··-------------------············ 15 

Idaho specimens ............................................ 22, 25 

idahoensis, Toernquistia .......................... 22; pl. 4 

Ikes Canyon ...................................................... 9 

Illaenid ................................................................ 5 

sp 1 ...................................................... 21; pl. 4 

sp 2 --------------------·--------------··················· 21 ; pl. 4 

Illaenid genus, indeterminate ...................... 21 

Illaenidae ............................................................ 21 

llla.enus ... _____ ---------------···············-----·-----------------· 22 

auriculatus .................................................. 22 

uta.hensis ---------------------------------------------------- 9 

sp ----------------------------·------------------------------------- 5, 7 

Independence Mountains .......................... 1, 3, 12 

stratigraphic section .............................. 9 

Indeoendence quadrangle ............................. . 

intermedius, Orthograptus truncatus ...... 10, 11 

Investig-ations, previous -------------------------------- 1 

Inyo Mountains, Calif., northern .......... 1, 3, 20 

northern, stratigraphic section ............ 9 

Isoteloid genera, characteristics .................. 18 

INDEX 

Page 

lsoteloides ........................................................ 18, 19 

lsotelus .............................................................. 18, 19 

copenhagenensis ...... 4, 5, 6, 10, 18 ; pls. 2, 3 

gigas ............................................................ 19 

harrisi .......................................................... 19 

sp -------------·---------············---·························· 4, 5, 6 

J, K 

Joins Formation 7, 11 

Kanosh Shale .................................................... 7 

Karlins, 0. L., fossil identifications .... 4, 5, 6, 8 

quoted ---·--------------------·--·---··········-···--·-····· 4, 6, 8 

Kiesley Limestone ............................................ 22 

Komaspididae ----······-----···--------------·················-·· 14 

L 

lanceolatus, Oistodus 

Lannacus ------·---------------------------···-·-··------------······ 

Laticrura heteropleura ................................. . 

Leptellina occidentalis ................................... . 

sp --- ···········---------------------------------------------------

Leray Formation ............................................. . 

Lichid ---------------------·----------------------------·---------------

Lichidae ..................................................... . 

7 

18 

9 

5 

4, 9 

6 

4 

28 

Localities and collections .............................. 12 

Lonchodomas .................................................... 25 

halli .............................................................. 25 

normalis ...................................................... 25 

retrolatus .................................................... 25 

sp .................................................. 3, 5, 25 ; pl. 6 

Lone Mountain .................................................. 12 

lorrettensis, Cryptolithus .............................. 23 

M 

Maclurites sp .................................................... 9 

maconachiei, Raymondella ---------------·------------ 26 

Macrocoelia ........................................................ 10 

sp .................................................................. 6, 9 

major, Robergia ........................................ 16; pl. 1 

Maquoketa Shale ............................................ 20, 21 

Martin Ridge .............................................. 3, 10, 21 

eastside, fossils ........................................ 5 

martinensis, A nata ph rus .............................. 3, 

4, 7, 10, 20, 26; pl. 3 

Masket Shale .................................................... 9 

McLish Formation ...................................... 5, 9, 11 

Measured section, Belted Peak area .......... 8 

Megalaspides ...................................................... 18 

Meiklejohn Peak .............................................. 5 

stratigraphic section .............................. 9 

Member A .......................................................... 1 

Belted Peak area ...................................... 9 

Member B ........................................................ 1, 3, 5 

age of trilobite fauna .............................. 10 

Belted Peak area ...................................... 9 

Clear Creek Canyon ................................ 6, 7 

fossils .......................................................... 6 

Hot Creek Canyon .................................. 7 

Independence Mountains ........................ 10 

northern Inyo Mountains, Calif .......... 9 

Rawhide Mountain .................................. 8 

Member C ............ ............................................. 3 

age of trilobite fauna ............................ 10 

Antelope Valley ........................................ 3 

Toquima Range ........................................ 9 

merriami, Sowerbyella .................................... 4 

micronthalmus, Robergia .............................. 15 

Mill Canyon ...................................................... 5 

Mill Canyon sequence ...................................... 9 

minganensis, Amphilichas ...... 4, 5, 10, 28; pl. 7 

M iraspis .............................................................. 28 

sp .................................................... 28, 29 ; pl. 7 

Monitor Range ............................................ 1, 7, 10 

monitorensis, Belodina .................................... 6 

Oxoplecia .................................................... 9 

Monticuliporid sp ............................................ 5, 8 

Mountain Lake Member, Bromide 

Formation .................................. 4, 10 

Multicostella sp .............................................. 4, 6, 8 

N Page 

N anillaenus ........................................................ 21 

sp ························------------·-----·------------·------···· 6 Nevada specimens ........................................ 18, 22 

Nevada Test Site .................................. 3, 9, 10, 25 

nevadensis, Oxoplecia .................................... 4 

Raymondella ---------·------------············ 3, 25 ; pl. 6 Newfoundland .................................................. 15 

nicholsoni, Toernquistia ................................ 3, 22 

Nileidae .............................................................. 21 

Nileoides perkinsi ............................................ 20 

Nileus .................................................................. 21 

sp ...................................................... 4, 21 ; pl. 4 

normalis, Lonchodomas .................................. 25 

0 

obesa, Plectorthis .......................................... . 4 

obtusus, Vogdesia ............................................ 20 

occidentalis, Leptellina .................................. 5 

Odon topleuridae ................................................ 28 

Ogygioca1·is ........................................................ 15 

Oil Creek Formation ...................................... 11 

Oistodus clmtractus ........................................ 7 

lanceolatus .................................................. 7 

sp ................................................................. . 6 

Oklahoma specimens ...................................... 22 

oklahomensis, Anomalorthis ........................ 7 

Olenidae .............................................................. 14 

Onychopyge sculptura .................................... pl. 1 

Oranda Formation ........................................ 10, 11 

ornata, Belodina .............................................. 8 

Orthambonites sp ............................................ '1 

Orthid .................................................................. 4 

Orthidiella zone ................................................ 14 

Orthograptus truncatus intermedius ........ 10, 11 

truncatus pertenuis ................................ 11 

strigosus ............................................ 11 

sp ·········-·····································---·---------------

Ostracodes ......................................................... . 

Antelope Valley, hill 8308 ................... . 

Clear Creek Canyon ............................... . 

Rawhide Mountain ................................. . 

Ottoseetaxis bipartitus ................................. . 

sp ---------·-······················································· 

Oulodus sp ......................................................... . 

Oxoplecia monitorensis ................................. . 

nevadensis ................................................. . 

Ozarkodina tenuis ........................................... . 

p 

Pachydictyid 

Paltodus sp ....................................................... . 

11 

11 

4 

6 

8 

5 

5 

7 

9 

4 

5, 8 

7 

Paraceraurus ruedemanni .............................. 27 

Paraharpes ........................................................ 22 

pelagia, Carrickia ............................................ 14 

perkinsi, Nileoides ---------------------------------------··· 20 

perplexa, Sowerbyella ...................................... 9 

pertenuis, Orthograptus truncatus ............ 11 

Pete Hanson Creek ...................................... 12, 24 

Phragmodus undatus ...................................... 6, 8 

Phyllodictya c1·ystaUaria ................................ 5 

phyllophorus, Climacograptus ...................... 4 

plana, Va.lcourea .............................................. 4 

Plectambonitid .................................................. 4, 5 

Plectorthis obesa .............................................. 4 

sp -------------···················--------------------·············· 

Polyplacognathus ramosa ............................. . 

Pooleville Member, Bromide Formation ... . 

Porterfieldia ..................................................... . 

powelli, A mpyxina ......................................... . 

prima, Cybeloides ........................................... . 

Goniophrys 

4 

12 

20 

14 

25 

27 

14 

Primaspis .................................................. 11, 28, 29 

churkini ................................................ 29 ; pl. 8 

harnagensis ................................................ 29 

sp ............................................................ 5, 28, 29 

Prioniodina sp ................................................. . 8 

Protozyga sp ..................................................... . 9 
Pterygometopidae 

Punctaparchites sp ......................................... . 

R 

Page 

27 

6 

ramosa, Polyplacognathus .............................. 12 

~anger Mountains .................................. 3, 5, 9, 20 

Raphiophoridae ··········---·····--··············-·········--·· 25 

Rawhide Mountain .......................................... 9 

stratigraphic section .............................. 8 

Raymondella ····----------------------------·--····--···-------- 10, 25 

e/egans ··············--------------------------------·-········ 26 

maconachiei ................................................ 26 

nevadensis ··············---------·······-------- 3, 25 ; pl. 6 

Receptaculites sp --·-··········-···················-·····---- 4, 9 

References cited ................................................ 29 

Remopleurididae ---------········-------------------······-··· 15 

Remopleurides ---·--·-·········------------·-·········-------- 10, 17 

eximi1ts ....... ······················-------------------·-····· 17 

sim.ulus ........................................................ 17 

sp -------·-······--------------···························----···--· 3, 7 

sp. 1 ---------------------------·---··-···················· 17; pl. 1 

sp. 2 ··············-·····---------···------------------------17; pl. 1 

reticulatus, Cryptolithoides .... 3, 23, 24 ; pis. 4, 5 

retrolatus, Lonchodomas ------------·-·····--------····· 25 

Reuschella ····--·-······--··-----··········-------------·········--- 7 

Rhinidictyidae ··············---····------------------·----·-···· 8 

Robergia ---------····-··············-----------·------------------ 10, 15 

deckeri --------------·-··············--··---- 3, 16, 17; pl. 1 

major .................................................... 16; pl. 1 

micropthalmus .......................................... 15 

schlotheimi .............................................. 15, 17 

yukonensis --····--------------------···· 15, 16, 17 ; pl. 1 

Robergiella ...................................................... 10, 17 

sagittalis ·····-··········--------- .......................... 18 

sp -···········-----·-····-················--·······----- 3, 17; pl. 2 

Roberts Mountains ........................................ 12, 24 

Roberts Mountains Formation .................... 9 

robustus, Sagittodontus .................................. 6, 12 

Rockland Formation ...................................... 8 

ruedemanni, Paraceraurus 27 

s 

sagittalis, Robergiella ········---·----------·············· 18 

Sagittodontus robustus .................................. 6, 12 

salmoni, Ampyxina ............................ 16, 25; pl. 6 

Saturday Mountain Formation .. 6, 12, 25, 27, 29 

Scandodus ······-··············-············-····-····-····--------- 7 

schlotheimi, Robergia -------·-----··············-········ 15, 17 

Scolopodus .......................................................... 7 

INDEX 

Page 

Scotland, southwestern ··········------------·----·····-- 10 

Ayrshire ----······-··········-------··········---·-··········· 22 

Girvan District .............................. 15, 26 

Sculptura onychopyge .................................... pl. 1 

setoni, Carrickia ............................................ 14, 15 

Severella sp ........................................................ 6 

Sherman Fall Formation .............................. 11 

Shoreham Member .................................. 11 

Shoreham Member, Sherman Fall 

Formation .................................. 11 

Simpson Group ................................................ 8, 11 

simulus, Remopleurides .................................. 17 

Skenidioides sp .................................................. 4 

Sowe1·byella men·iami .................................... 4 

perplexa ...................................................... 9 

sp .................................................... 4, 5, 8, 9, 10 

Sowerbyites ........................................................ 10 

sp .................................................................. 6, 9 

Sphaerocoryphe ................................................ 27 

sp ...................................................... 4, 27; pl. 7 

Sponges, Antelope Valley, hill 8308 .......... 4 

spurius, A nataphrus ................................ 8, 20, 21 

Stegnopsis .......................................................... 18 

Stictoporella sp ................................................ 5 

Stictoporellid .................................................... 5 

Stinchar Limestone ........................................ 15 

strasburgensis, Ca,lyptaulax .......................... 9 

striatulus, llypodicranotus ............................ 15 

strigosus, Orthogi•·aptus truncatus ............ .. 

Strophomena ................................................... . 

sp ................................................................ . 

Strophomenoid .................................................. . 

suberectus, Drepanodus ................................. . 

symmetricus, Disl'acodus ............................... . 

Synprioniodina sp ........................................... . 

T 

11 

10 

4 

4, 5 

6, 7 

7 

7 

Table Head Formation .................................. 15 

tenuis, Ozarkodina .......................................... 6 

tesselatus, Cryptolithus .................................. 23 

Tetraprioniodus costatus ................................ 7 

Thaleops sp ...................................................... pl. 8 

Toernquist~a .................................................... 22, 26 

idahoensis .............................................. 22; pl. 4 

nicholsoni .................................................. 3, 22 

Tonopah 2° quadrangle ................................ 6, 7 

Toquima Range ............................................ 3, 9, 10 

stratigraphic section .............................. 9 

transversa, Valcourea .................................... 4 

Trenton Group ................................................... 12 

33 

Page 

Trenton Limestone .......................................... 11 

Trepostome sp .................................................. 5 

Trepostomes ...................................................... 6, 8 

Triarthrinae ...................................................... 14 

Triarthrus ........................................................ 10, 14 

caecigenus .................................................. 14 

sp ...................................................... 3, 14; pl. 1 

Trichonodella barbara .................................... 6 

sp .................................................................. 7, 8 

Trilobites ............................................................ 1, 12 

age .... ......................................................... 10 

Antelope Valley, hill 8308 .................... 3 

Belted Peak area ...................................... 8 

Clear Creek Canyon ................................ 6 

descriptions ................................................ 14 

Hot Creek Canyon .................................. 6, 7 

Toquima Range ........................................ 9 

Trinucleidae ...................................................... 22 

truncatus inte1·medius, Orthograptus ...... 10, 11 

pertenuis, Orthograptus ........................ 11 

strigosus, Orthograptus .......................... 11 

Tuscarora quadrangle .................................... 9 

typica, Dichognathus ...................................... 6 

typicalis, Climacograptus .............................. 11 

U,V 

ulrichi, Cryptolithoides .................................. 24 

Homotelus .................................................. 20 

Unconformities ................................................ 1 

undatus, Phragmodus ...................................... 6, 8 

utahensis, lllaenus .......................................... 9 

Valcourea .......................................................... 7, 10 

plana . ........................................................... 4 

transversa .................................................. 4 

sp ......................................................... 5, 6, 8, 9 

vigilans, Anataphrus .................................... 20, 21 

Viola Limestone .................... 10, 11, 12, 15, 16, 24 

virginiensis, Cybeloides .................................. 27 

V ogdesia ............................................................ 20 

bearsi .......................................................... 20 

obtusus 20 

W, Y, Z 

West Shropshire, England ............................ 14 

Wildcat Peak quadrangle .............................. 9 

Yukon specimens .......................................... 16, 24 

yukonensis, Robergia .................. 15, 16, 17; pl. 1 

Zygognathus sp ................................................ 8 

PLJ~TES 1-8 

[Contact photographs of the plates in this report are available, at cost, from the U.S. Geological Survey Library, 

Federal Cent,er, Denver, Colorado 80225] 
PLATE 1 

FIGURE 1. Triarthrus sp. (p. 14) 

USGS colln. D1914 CO. Cranidium; dorsal view. Stereophotograph; X 6. USNM 169601. 

2. Carrickia? sp. (p. 14) 

USGS colin. D1860 CO. Cranidium; dorsal view, left fixigene and glabella. Stereophotograph; X 5. USNM 

169602. 

3-7. Hypodicmnotus n. sp. (p. 15) 

All figures are stereophotographs. 

3. Pygidium; dorsal view. X 10. USGS colin. D1873 CO. USNM 169603a. 

4, 6. Cephalon; left lateral and dorsal views. X 2. USGS colin. D1873 CO. USNM 169603b. 

5. Free cheek; dorsal view. X 4. Loc. SR ( -30) (30ft below USGS colin. D1880 CO). USNM 169604. 

7. Hypostome, incomplete; ventral view. X 5. USGS colin. D1874 CO. USNM 169605. 

8-15. Robergia 'major Raymond. (p. 16) 

Figures 9-15 photographed by F. C. Shaw. 

8. Pygidium; dorsal view. Stereophotograph; X 5. USGS colln. D1914 CO. USNM 169606. 

9. Pygidium; dorsal view. X 3. Loc. GK. AMNH 29106. 

10. Cranidium; dorsal view. X 3. Loc. GK. AMNH 29107. 

11. Pygidium; interior of mold of dorsal surface. X 3. Loc. GK. AMNH 29108. 

12. Pygidium; dorsal view. X 3. Loc. GK. AMNH 29109. 

13. Pygidium; interior of mold of dorsal surface. X 3. Loc. GK. AMNH 29110. 

14. Cranidium, partial; interior of mold of dorsal surface. X 3. Loc. GK. AMNH 29111. 

15. Cranidium; dorsal view. X 3. Loc. GK. AMNH 29112. 

16-21. Robergia deckeri B. N. Cooper. (p. 16) 

All figures are stereophotographs. 

16. Cranidium, partial; dorsal view. X 10. USGS colin. D1880 CO. USNM 169607a. 

17. Cranidium; dorsal view. X 3. Loc. CC (Same as USGS colin. D1915 CO.) USNM 169608a. 

18. Pygidium, damaged; dorsal view. X 6. Loc. CC (essentially same as USGS colln. D1915 CO). USNM 

169608b. 

19. Pygidium; dorsal view. X 6. Loc. CC ( essentially same as USGS colln. D1915 CO). Note doublure and 

its markings on right side. USNM 169608c. 

20. Cranidium, partial; dorsal view. X 7. USGS colin. D1880 CO. Note crease in front of glabella resembling 

that of R. yukonensis Lenz and Churkin. USNM 169607b. 

21. Pygidium, juvenile; dorsal view. X 10. USGS colin. D1880 CO. This pygidium strongly resembles that of 

Onychopyge sculptw·a Robison and Pantoja-Alor (1968, pl. 100, figs. 4, 5). USNM 169607c. 

23. Remopleurides sp. 1 (p. 17) 

Cranidium; dorsal view. Stereophotograph; X 3. Float, with USGS colln. D1880 CO. USNM 169609. 

22, 24, 25. Remopleurides sp. 2. (p. 17) 

Cephalon; dorsal, lateral, and anterior views. Stereophotographs; X 4. USGS colin. D1860 CO. USNM 169610. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE I 

TRIARTHRUS, CARRICKIA?, HYPODICRANOTUS, ROBERG/A, AND REMOPLEURIDES 
PLATE 2 

[All figures are sle r eophotographs except figures 4, 7, 11] 

FIGURES 1, 2. Robm·giella sp. (p. 17) 

1. Cranidium; dorsal view. x 6. Loc. CC (essentially same as USGS colin. D1915 CO). USNM 169611. 

2. Cranidium; dorsal view. X 7. USGS colin. D1880 CO. USNM 169612. 

3-11. Isot elus copenhagenensis, n. sp. (p. 18) 

3. Hypostome, paratype; mold of ventral surface. X 3. USGS colin. D1914 CO. USNM 169613. 

4. Cranidium, holotype; dorsal view. X 1. USGS colin. D1878 CO. USNM 169614. 

5. Pygidium, paratype; dorsal view. X 1. USGS colin. D286 CO. USNM 169615a. 

6. Pygidium, paratype; dorsal view. X 1. USGS colin. D1905 CO. USNM 169616a. 

7. Pygidium, paratype, largest specimen obtained; dorsal view. X 1. USGS colln. D1874 CO. USNM 169617. 

8. Cranidium, paratype; dorsal view. X 1. USGS colin. D1872 CO. USNM 169618a. 

9. Partial cephalon and thorax; dorsal view. X 1. USGS colin. D249c CO. USNM 169619. 

10. Pygidium; dorsal view. x 1. USGS colin. D1872 CO. USNM 169618b. 

11. Pygidium; dorsal view. X 1. USGS colin. D1905 CO. USNM 169616b. 
GEOLOGICAL SURVEY 

ROBERGIELLA AND ISOTELUS 

.. ~ ... 

~"r-, : .. ~~to • 

PROFESSIONAL PAPER 749 PLATE 2 
PLATE 3 

[All figures stereophotographs except figure 15] 

FIGURES 1-3. Isotelus copenhagenensis n. sp. (p. 18) 

1. Cranidium, para type; dorsal view of a latex cast. X 1. USGS colin. D286 CO. USNM 169615b. 

2. Free cheek, paratype; lateral view, showing height of eye. X 1. USGS colin. D1905 CO. USNM 169616c. 

3. Hypostome, para type; ventral view. X 2. USGS colin. D1905 CO. USNM 169616d. 

4-16. A nataphrus nw1·tinensis n. sp. (p. 20) 

4-6. Cephalon, paratype; dorsal, anterior, and lateral views. X 2. USGS colin. D1912 CO. USNM 169621. 

7. Pygidium, para type; dorsal view. x 1. USGS colin. D1880 CO. USNM 169622. 

8, 10, 11, 14. Holotype, enrolled individual, anteriorly deformed; dorsal, anterior, lateral, and posterior 

views. X 2. USGS colin. D1872 CO. USNM 169623. 

9, 12, 13, 15. Para type, nearly complete individual; dorsal, anterior, ventral, and lateral views. X 2. Figure 

13 shows median suture cutt ing doublure. Loc. MR-U. USNM 169624a. 

16. Pygidium, paratype; dorsal view showing doublure beneath decorticated portion of carapace. X 2. Loc. 

MR-U. USNM 169624b. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE 3 

ISOTELUS AND ANATAPHRUS 
PLATE 4 

(All figures are slereophotographs except figures 3, 6, 8, 9, 11) 

FIGURE 1. Nileus? sp. (p. 21) 

Cranidium; dorsal view. X 3. Loc. SR-L (100ft below USGS colin. D1880 CO). USNM 169625. 

2, 3. Illaenid sp. 1 (p. 21) 

Cranidium; dorso-lateral view and dorsal view. X 1. Loc. MR-U. USNM 169626. 

4, 5. Illaenid sp. 2 (p. 21) 

Cranidium; anterior and dorsal views. X 4. Loc. MR-U. USNM 169627. 

6-9. Toernquistia? idahoensis Churkin (p. 22) 

6. Cranidium; dorsal view. X 6. Loc. GK. AMNH 29113. 

7. Cranidium; dorsal view. X 5. USGS colin. D1914 CO. USNM 169628. 

8. Cranidium, partially obliterated; dorsal view. X 6. Loc. GK. AMNH 29114. 

9. Cranidium, interior of mold; ventral view. X 6. Loc. GK. AMNH 29115. 

10. Harpid genus, indeterminate (p. 22) 

Latex cast. Partly preserved cephalon, lacking glabella; dorsal view. X 2. USGS colin. D249a CO. USNM 169629. 

11-19. Cryptolithoides re ticulatus n. sp. (p. 24) 

11. Part of left side of cephal on, para type; dorsal view showing long genal spine. X 3. USGS colin. D1880 CO. 

USNM 169631a. 

12. Cephalon, paratype; dorsal view. x 2. USGS colin. D1880 CO. USNM 169631b. 

13, 15, 18. Cephalon, paratype; dorsal, anterior, and lateral views. X 2. USGS colin. D1880 CO. USNM 169631c. 

14. Partial cephalon, para type; dorsal view showing length of genal spine. X 3. USGS colin. D1880 CO. USNM 

169631d. 

16, 17, 19. Holotype, cephalon ; dorsal view showing reticulation on cheek lobes. X 2. USGS colin. D1880 CO. 

USNM 169630. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE 4 

NILEUS?, ILLAENID TOERNQUISTIA?, HARPID, AND CRYPTOLITHOIDES 
PLATE 5 

[All figures are stereophotographs] 

FIGURES 1-17, 19. C1·yptolithoides reticulatu8 n. sp. (p. 24) 

[All specimens are paratypes] 

1. Pygidium; dorsal view. X 3. USGS colln. D1880 CO. USNM 169631e. 

2. Pygidium; dorsal view. X 3. USGS colln. D1880 CO. USNM 169631f. 

3. Cephalon, partial; dorsal view showing genal spine. X 3. USGS colln. D1880 CO. USNM 169631g. 

4. Cranidium; dorsal view showing reticulate surface of cheek lobes and base of occipital spine. X 3. 

USGS colln. D1880 CO. USNM 169631h. 

5, 6, 10. Cranidium; dorsal, anterior, and lateral views. X 2. USGS colln. D1880 CO. USNM 169631i. 

7, 8, 12. Cranidium, immature; dorsal, anterior, and lateral views. X 5. USGS colln. D1880 CO. USNM 

169631j. 

9, 13. Cranidium; lateral and dorsal vi ews, latex cast. X 2. USGS colln. D1880 CO. USNM 169631k. 

11, 14. Cranidium, immature; lateral and dorsal views. X 7. USGS colln. D1880 CO. USNM 1696311. 

15. Pygidium; dorsal view. X 3. Loc. CC (essentially same as USGS colin. D1915 CO). USNM 169632a. 

16. Nearly complete carapace; dorsal view, latex cast. X 2. USGS colln. D1914 CO. USNM 169633. 

17. Cranidium, immature; dorsal view showing eyes and eye ridges. X 10. USGS colin. D1880 CO. 

USNM 169631m. 

19. Cephalic fringe; ventral view showing girder. X 2. Loc. CC (essentially same as USGS colln. 

D1915 CO). USNM 169632b. 

18, 20, 21, 23. Ct·ypto lithoides fittsi (p. 24) 

18, 20, 21. Cranidium; anterior, lateral, and dorsal views. X 2. USGS colin. D1880 CO. USNM 169634. 

23. Cranidium; dorsal view. X 2. Loc. CC (essentially same as USGS colln. D1915 CO) . USNM 169635. 

22. Cryptolithoides sp. (not described) 

Cranidium; dorsal view, latex cast. X 3. Lower part of Viola Limestone, 3.5 miles north of Baum, Okla., 

on Okla. Highway 18. F. C. Shaw collection. USNM 169661. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE 5 

CRYPTOLITHOIDES 
PLATE 6 

[All figures arc stcrcophotographs except figures 5, 6, 9, 10] 

FIGURES 1-3. Lonchodomas sp. (p. 25) 

1, 2. Cranidium; dorsal and lateral views. X 2. USGS colln. D249a CO. USNM 169636. 

3. Cranidium; interior of natural mold, with anterior spine partly preserved. X 3. USGS colln. D1913 CO. 

USNM 169637. 

4-10. Ampyxina salmoni Ch urkin (p. 25) 

4. Nearly complete specimen; dorsal view. X 3. USGS colln. D1914 CO. USNM 169638. 

5. Cranidium; dorsal view. X 3. Loc. GK. AMNH 29116. 

6. Nearly complete specimen; dorsal view. X 6. Loc. GK. AMNH 29117. 

7. Cranidium, poorly preserved; dorsal view. X 3. USGS colln. D1916 CO. USNM 169639a. 

8. Pygidium; dorsal view. X tl. USGS colln. D1916 CO. USNM 169639b. 

9. Nearly complete specimen; dorsal view. x 6. Loc. GK. AMNH 29120. 

10. Cephalon and partial thorax; dorsal view. X 3. Loc. GK. AMNH 29121. 

11-13, 15, 17. Raymondella nevadensis n. sp. (p. 25) 

11. Pygidium, para type; dorsal view. x 10. USGS colln. D1914 CO. USNM 169641a. 

12. Pygidium, para type; dorsal view. X 10. USGS colln. D1880 CO. USNM 169642a. 

13. Pygidium, para type; dorsal view. X 10. USGS colin. D1914 CO. USNM 169641b. 

15. Holotype, cranidium ; dorsal view. X 7. USGS colln. D1914 CO. USNM 169640. 

17. Cranidium, paratype; dorsal view. X 10. USGS colln. D1880 CO. USNM 169642b. 

14. Ceraurinella sp. (p. 26) 

Cranidium; dorsal view. X 4. USGS colln. D1880 CO. USNM 169643. 

16. Cheirurinid genus, indeterminate (p. 27) 

Cranidium, fragmentary; dorsal view, latex cast. x 1. USGS colin. D1876 CO. USNM 169644. 

18. Cemu rus ? sp. (p. 26) 

Cranidium, fragmentary; dorsal view, latex cast. X 4. USGS coiJn. D1860 CO. USNM 169645. 

19. Cybeloides sp. (p. 27) 

Pygidium; dorsal view. X 10. USGS colln. D1874 CO. USNM 169646. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE 6 

LONCHODOMAS, AMPYXINA, RAYMONDELLA, CERA URINELLA, 

CHEIRURINID, CERAURUS?, AND CYBELOIDES 
PLATE 7 

[All figures are stereophotographs except figur es 3-7] 

FIGURES 1, 2. Sphaerocm·yphe sp. (p. 27) 

Cranidial bulb; dorsal and left lateral views. X 7. USGS colin. D1874 CO. USNM 169647. 

3-8. Calymenid genus, indeterminate (p. 27) 

3. Pygidium; dorsal view, latex cast. X 3. Loc. GK. AMNH 29122. 

4. Pygidium; dorsal view. X 3. USGS colin. D1914 CO. USNM 169660. 

5. Pygidium, partial cast; dorsal view. X 3. Loc. GK. AMNH 29123. 

6. Cranidium, partial; dorsal view. X 3. Loc. GK. AMNH 29124. 

7. Cranidium; ventral view of mold. X 3. Loc. GK. AMNH 29125. 

8. Pygidium; dorsal view. X 3. USGS colin. D1916 CO. USNM 169648. 

9-15. Calyptaulax cf. C. calli1·achis (B. N. Cooper) (p. 28) 

9. Cephalon, mostly decorticated; dorsal view. X 4. Loc. MR. USNM 169649a. 

10, 14. Cephal on; dorsal and lateral views. X 3. Loc. MR. USNM 169649b. 

11. Hypostome; ventral view. X 10. USGS colin. D1880 CO. USNM 169650a. 

12, 13. Pygidium; dorsal and posterior views. X 3. Loc. MR. USNM 169649c. 

15. Pygidium; dorsal view. X 3. Loc. SR (same as USGS colin. D1880 CO). USNM 169650b. 

16-20, 23. Amphilichas aff. A. minganensis (Billings) (p. 28) 

16. Hypostome; ventral view. X 3. USGS colin. D1874 CO. USNM 169651a. 

17-20. Cranidium; lateral, anterolateral, dorsal, and anterior views. X 1. USGS colin. D1874 CO. USNM 

169651b. 

23. Pygidium, fragmentary; dorsal view, latex cast. X 3. USGS colin. D249a CO. USNM 169652. 

21, 22. Mimspis sp. (p. 28) 

21. Cranidium; dorsal view. X 5. USGS colin. D1915 CO. USNM 169653a. 

22. Cranidium; dorsal view. X 5. USGS colin. D1915 CO. USNM 169653b. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE 7 

SPHAEROCORYPHE, CALYMENID, CALYPTAULAX, AMPHILICHAS, AND MIRASPIS 
PLATE 8 

[All figures are stereophotogr aphs except figures 2, 4, 5] 

FIGURES 1- 10. P1·irnaspis churkini n. sp. (p. 29) 

1. Cranidium, holotype; dorsal view, latex cast. X 5. USGS colln. D1916 CO. USNM 169654. 

2. Pygidium, para type, mold of posterior spines; dorsal view. X 6. Loc. GK. AMNH 29126. 

3. Pygidium, para type, latex mold; dorsal view. X 5. USGS colln. D1916 CO. USNM 169655a. 

4. Free cheek, natural mold; dorsal view. X 6. Loc. GK. AMNH 29127. 

5. Pygidium; dorsal view. X 6. Loc. GK. AMNH 29128. 

6. Pygidium; dorsal view. X 5. USGS colln. D1916 CO. USNM 169655b. 

7. Cranidium; dorsal view. X 5. USGS colln. D1916 CO. USNM 169655c. 

8. Cranidium; dorsal view. X 3. USGS colln. D1916 CO. USNM 169655d. 

9. Cranidium; dorsal view. X 5. USGS colln. D1916 CO. USNM 169655e. 

10. Hypostome; ventral view. X 4. USGS colin. D1914 CO. USNM 169656. 

11-16, 18. Thaleops sp. (not described) 

USGS colln. D2215 CO, Copenhagen Formation, member B of Merriam, east side of Martin Ridge, Horse 

Heaven Mountain quadrangle, Nevada. 

11, 14, 15, 18. Cranidium; lateral, dorsal, anterior, and posterodorsal views. X 1. USNM 169657a. 

12, 13, 16. Cranidium, immature; dorsal, anterior, lateral views. X 2. Note pitted surface. USNM 169657b. 

17, 19, 20. Encr-inuroides sp. (not described) 

USGS colln. D2216 CO, Copenhagen Formation, member C of Merriam, east side of Martin Ridge, Horse 

Heaven Mountain quadrangle, Nevada. 

Cranidium; lateral, dorsal, and anterior views. X 3. USNM 169658. 

U. S. GOVF.RNiVIENT PRINTING OFFICE : 197 2 0- 460- 190 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 749 PLATE 8 

PRIMASPIS, THALEOPS, AND ENCRINUROIDES