Systematics, Environment, and Biogeography 

of Some Late Cambrian and 

Early Ordovician Trilobites From 

Eastern New York State 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 

Systematics, Environment, and Biogeography 

of Some Late Cambrian and 

Early Ordovician Trilobites From 

Eastern New York State 

By MICHAEL E. TAYLOR and ROBERT B. HALLEY 

GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 

The environmental setting and regional significance of 

two trilobite assemblages from shelf deposits of the 

fVhitehall Formation in the southern Champlain Valley 

UNITED STATES GOVERNl\1ENT PRINTING OFFICE, WASHINGTON 197 4 
UNITED STATES DEPARTMENT OF THE INTERIOR 

ROGERS C. B. MORTON, Secretary 

GEOLOGICAL SURVEY 

V. E. McKelvey, Director 

Library of Congress catalog-card No. 73-60031 S 

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

Washington, D.C. 20402 - Price $1.35 (paper covers) 

Stock Number 2401-02459 
Abstract 

Introduction 

Objectives -----------------------------------

Geologic setting -----------------------------

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

Fossil collections -----------------------------

Acknowledgments -- _-------------------------

Biostratigraphy ---------------------------------

Composition of Whitehall fauna --------------

Trilobites --- _ ---------------------------

Gastropods ______ - -- __ -------------------

Other fossils ----------------------------

Age and correlations -------------------------

Problems and methods -------------------

Saukia Zone -----------------------------

Missisquoia Zone ------------------------

Symphysurina B Zone ( ?) ----------------

Cambrian-Ordovician boundary ---------------

Summary ----------------------------------- Environmental setting ______________________ ----- Petrology __________________________________ _ 

Inferred environments -----------------------

Biofacies distribution ----------------------------

~odels -------------------------------------- ~ethods of analysis ------------------------- Assemblages similar to Whitehall fauna ______ _ 

Assemblages dissimilar to Whitehall fauna ____ _ 

CONTENTS 

Page 

1 

1 

1 

1 

2 

2 

2 

4 

4 

4 

4 

4 

4 

4 

6 

6 

8 

8 

9 

9 

9 

10 

12 

12 

13 

13 

16 

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

Introductory statement ----------------------

Class Trilobita Walch, 1771 ------------------

Family Catillicephalidae Raymond, 1938 ---

Genus Acheilops Ulrich, 1931 ---------

Genus Stenoc.hilina Ulrich, 1931 -------

Family Heterocaryonidae Hupe, 1953 _____ _ 

Genus Bowmania Walcott, 1925 -------

Family Mis,sisquoiidae Hupe, 1953 ---------

Genus Missisquoia Shaw, 1951 --------

Family Plethopeltidae Raymond, 1925 ____ _ 

Genus Plethometopus Ulrich, 1931 

Genus Plethopeltis Raymond, 1913 ----

Family Ptychaspididae Raymond, 1924 ----

Subfamily Ptychaspidinae Longacre, 

1970 ----------------------------- Genus Euptychaspis Ulrich, 1931 -----

Subfamily Saukiinae Ulrich and Resser, 1933 

Genus Calvinella Walcott, 1914 --------

Genus Prosaukia Ulrich and Resser, 

1933 ------------------------------

Family Solenopleuridae Angelin, 1854 ------

Genus Hystricurus Raymond, 1913 -----

Description of fossil localities -------------------- References cited _________________________ -- __ ----

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

ILLUSTRATIONS 

[Plates foHow index] 

PLATE 1. Plethopeltis, Acheilops, Stenochilina, and Plethometopus. 

2. "Calvinella," Euptychaspis, BoH)mania, and "Prosaukia." 

3. Missisquoia and Hystricurus. 

4. Photomicrographs of petrographic thin sections. 

FIGURE 1. 

2. 

3-5. 

6. 

Geologic map showing fossil localities discussed in text ------------------------------------------

Columnar section showing typical repetition o.f components in limestones of the lower Whitehall Formation ----------------------------------------------------------------------------------------- Photograph showing3. Sharp vertical contact between crossbedded grainstone and finer grained clotted thrombolitic 

fabric ------------------------------------------------------------------------------ 4. Domal stromatolites in the lower part of the Whitehall Formation -------------------------· 

5. Domal thrombolite in the lower Whit·ehall Formation ---------------------------------------

Map showing the general location of principal areas of North America from which Saukia. Zone faunas 

have been reported --------------------------------------------------------------------------

III 

Page 

18 

18 

19 

19 

19 

20 

21 

21 

22 

22 

23 

23 

25 

26 

26 

26 

27 

27 

28 

31 

31 

32 

33 

37 

Page 

3 

10 

10 

11 

11 

14 
IV CONTENTS 

TABLES 

Page 

TABLE 1. The occurrence of identified taxa in samples studied and the inferred biostratigraphic zonal assignment__ 5 

2. Comparison of the biostratigraphic ranges of trilobite species and genera from the Whitehall Formation 

with occurrences in the central Great Basin, central Texas, and south-central Oklahoma _________ 7 

3. Known occurrences of trilobite sp,ecies recognized from the Saukia Zone at Whitehall, N.Y ------------ 16 

4. Known North American occurrences of trilobite genera recognized from the Saukia Zone at Whitehall, 

N.Y --------------------------------------------------------------------------------------- 17 
SYSTEMATICS, ENVIRONMENT, AND BIOGEOGRAPHY OF' 

SOME LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES 

FROM EASTERN NEW YORK STATE 

By MICHAEL E. TAYLOR and RoBERT B. HALLEY 1 

ABSTRACT 

The Whitehall Formation in Washington County, eastern 

New York Sta:te, has yielded two assemblages of trilobites, 

gastropods, and other fossHs, which are assigned to the 

Saukiella serotina Subzone of the Saukia Zone (Late Cambrian, Trempealeauan Stage) and to the M issisquoia Zone 

(Early Ordovician, Canadian Series). These occurrences 

suppor,t D. W. Fisher's interpretation that the CambrianOrdovician boundary, as currently recognized in North 

America, is within the Whitehall Formation. 

The lower part of the Whitehall contains domal s1tromatolites, thrombolites, and lime grainstones interpreted to have 

formed in supvatidal, intertidal, and shallow-subtidal marine 

environments. The vagile epibenthic fauna probably occupied 

warm-water, nearshore, shallow-subtidal habitats characterized by sustained moderate to high turbulence. Some 

limestone beds contain length-slow chalcedony which is 

thought to be an indicator of general hypersalinity or widely 

fluctuating salinity conditions in the environment of deposition. 

Comparison of the Trempealeauan taxa from the Whitehall with other occurrences in North America suggests that 

the fauna is part of a shelf biofacies commonly occurring 

in are,as of shallow-water carbonate deposition. The shelfcarbonate biofacies contrasts markedly with Trempealeauan 

trilobite ass,emblages that occupied sites of basinal sedimentllltion. 

The Whitehall faunas s,tudied contain 12 species of trilobites, 2 of which are indeterminate; at least 10 species of 

gastropods; Matthevia sp.; 2 species of Ribeiria, including 

Ribeiria cf. R. nuculiti/ormis Cleland, 1900; and 1 hyolithoid. Formal descriptions of trilobite's are given. Seven 

trilohi<te species are assigned to previously named taxa, two 

are placed in open nomenclature, and "Prosaukia" spinula 

Taylor is new. 

1 Department of Earth and Space Sciences, State University of New York, Stony Brook, NY 11790. 

INTRODUCTION 

OBJECTIVES 

Late Cambrian and Early Ordovician fossils from 

the Whitehall area of Washington County, eastern 

New York State, were studied to : ( 1) provide a 

more refined biostratigraphic classification of the 

Whitehall Formation than has been previously possible, (2) document the environmental setting of the 

Whitehall faunas, and (3) determine the biofacies 

relationship of the Whitehall Late Cambrian faunas 

relative to other known areas in North America. 

Study of the sedimentary environments of the 

Whitehall Formation was begun by Halley as part 

of a graduate research project at Brown University 

(Halley, 1971a). During the course of his fieldwork, 

Halley collected fossils and made preliminary identifications of the trilobites. The fossils were later sent 

to Taylor in February 1971 for examination and 

proved similar to some currently being studied from 

the Great Basin (Taylor, 1971). In this report Taylor has taken responsibility for taxonomic, biostratigraphic, and biogeographic aspects and Halley, for 

stratigraphic occurrence, description, and environmental analysis of rocks of the Whitehall Formation. 

GEOLOGIC SETTING 

The Whitehall area of eastern New York State is 

in the southern Champlain Valley in a narrow belt 

of Cambrian-Ordovician miogeosynclinal carbonate 

1 
2 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

and terrigenous clastic rocks which crop out between 

Precambrian rocks of the Adirondack Mountains to 

the west and the Cambrian-Ordovician Taconic sequence on the east (Theokritoff, 1964; Fisher, 1969). 

General geologic setting of the area is shown on the 

Adirondack Sheet of the Geologic Map of New York 

(lsachsen and Fisher, 1971), and the regional tectonic significance of the Whitehall area has been 

recently discussed by Rodgers (1970). The general 

location of the area studied and the geographic and 

geologic setting are shown in figure 1. 

PREVIOUS WORK 

The stratigraphy of the Whitehall area was described by Rodgers (1937). He named the Whitehall 

Formation for an easterly dipping sequence of interbedded sandstone, dolostone, and limestone cropping 

out on Skene Mountain at the east edge of the village 

of Whitehall, Washington County, N.Y. (fig. 1). 

The base of the formation is exposed on the west 

side of Skene Mountain about 120 feet below the 

crest (D. W. Fisher, written commun., 1972), and 

the top is exposed east of Skene Mountain (Rodgers, 

1937) in the shallow valley occupied by Norton Road 

(Washington County Route 9A). 

Wheeler (1942) formally recognized two members 

of the Whitehall Formation, a lower Hoyt Member 

and an upper Skene Member. Fisher (1956, 1968, 

1969) summarized the stratigraphy and rock-nomenclatural history of the Whitehall area and is currently engaged in detailed stratigraphic studies of Cambrian and Ordovician rocks in the region (D. W. 

Fisher, written commun., 1971). 

Cambrian fossils from the Whitehall area were 

described by Walcott (1912b) from possibly what 

are now termed the Potsdam and Ticonderoga Formations. The described fossils are older than those 

reported here. Wheeler (1941, 1942) was apparently 

the first to report Trempealeauan fossils from the 

Whitehall area, but his discoveries were never 

documented. 

FOSSIL COLLECTIONS 

Fossil collections used in this study came from 

three general sources. Robert B. Halley collected 

several fossil samples from the Whitehall Formation 

at Crossman quarry (H-1) and Warner Hill (H-2, 

H-3), north of the village of Whitehall, N.Y., during 1970. The senior author spent several days during fall 1971 examining Whitehall Formation outcrops in the vicinity of Whitehall and collected two 

samples (7098-CO, 7099-CO) from the upper part 

of the type section at Skene Mountain (fig. 1). 

Search of U.S. Geological Survey fossil collections 

in Washington, D.C., yielded several samples from 

the Whitehall area that proved relevant to this 

study. They include one sample collected by C. D. 

Walcott ( 418e), probably early in the 1900's, and 

several collections made by E. 0. Ulrich, Josiah 

Bridge, and Rudolph Ruedemann in 1931 (470b, 

470b1J 473f). The general geographic and geologic 

setting of the samples is shown in figure 1. Detailed 

locality information is given on page 32. 

Trilobites illustrated in this report are in the collections of the Department of Paleobiology, U.S. 

Museum of Natural History (USNM), Washington, 

D.C. Silicon rubber positive replicas of the illustrated specimens and representative nonillustrated 

material have been deposited in the New York State 

Museum, Albany, N.Y. All other nonillustrated material is in the trilobite collections of the U.S. Geological Survey, Washington, D.C. 

ACKNOWLEDGMENTS 

The authors especially wish to thank Donald W. 

Fisher for making available unpublished data on 

the Cambrian-Ordovician rocks and fossils of the 

Whitehall area and for his generosity in allowing 

us to publish a geologic index map prepared from 

his unpublished field data. Ellis L. Yochelson is 

thanked for providing gastropod identifications and 

John Pojeta, Jr., for identifying Ribeiria nuculitiformis Cleland. John H. Shergold originally pointed 

out the general similarity between Missisquoia and 

Parakoldinioidia. Taylor wishes to thank A. J. 

Rowell for several stimulating discussions on Late 

Cambrian biogeography. 

Halley thanks Conrad D. Gebelein, Donald W. 

Fisher, and A. R. Palmer for guidance in the field 

and Leo F. Laporte who supervised thesis research 

which led, in part, to the present report. The New 

York Geological Survey provided field funds to Halley during 1970. 

Persons to whom we are grateful for reading 

various versions of the manuscript and offering useful suggestions include: A. K. Armstrong, D. W. 

Fisher, J. F. Mello, A. R. Palmer, R. A. Robison, 

R. J. Ross, Jr., J. H. Shergold, J. H. Stitt, and E. L. 

Yochelson. 
43°32'30" 

EXPLANATION 

>- AUTOCHTHONOUS SEQUENCE 

!{ D BEDROCK COVERED 

6 Unconformity 

= rs : . A FORT CASSIN FORMATION 

:~ Disconformity 

~ 8-----i FORT ANN FORMATION 

kf£n1 CUTTING FORMATION 

Disconformity 

~ Upper part} WHITEHALL il EEill ~~:;~::~OG:OF::T~::N 

~ 1::::::\:1 POTSDAM SANDSTONE 

s:: Nonconformity 

~~{ l;:;::J METAMORPHICROCKS 

d 

INTRODUCTION 

ALLOCHTHONOUS SEQUENCE 

0 

[8] + . TACONIC SEQUENCE 

D TACONIC MELANGE 

Inferred fault 

Normal fault ~ Hachures on 

TTTT relatively downdropped side 

Thrust or reverse fault - Sawteeth 

on upper plate. Dashed where 

approximately located 

Contact - Dashed where 

approximately located 

~ Quarry 

,/ 6 Strike and dip of beds 

470b 

1 MILE VT 

X Foss~'llocality 

0 L/2 1 KILOMETER Whitehall 1~'~'~'~1-LI ______ ~I area 

CONTOUR INTERVAL 100 FEET ~ 

FIGURE !.-Geologic map showing fossil localities discussed in text. Detailed locality description are given on pages 

32 and 33. Geology is generalized from unpublished geologic maps made available through the courtesy of D. 

W. Fisher, New York State Museum and Science Service, Albany, N.Y. Base from Whitehall and Thorn Hill, New 

York-Vermont 772-minute quadrangles. 

3 
4 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

BIOSTRATIGRAPHY 

COMPOSITION OF WHITEHALL FAUNA 

The fauna here reported from the Whitehall Formation consists of 12 species of trilobites, two of 

which are indeterminate, at least 10 species of gastropods, fragmentary material referred to the problematical mollusk Matthevia, one indeterminate hyolithoid, and several bivalved fossils assigned to 

Ribeiria sp. and Ribeiria cf. R. nuculitiformis Cleland. Formal systematic descriptions are given for 

the trilobites. All taxa recognized are listed in table 

1 except those from locality 418e, which is discussed 

below. 

TRILOBITES 

Fossil sample H-3 from the Whitehall Formation 

on the north end of Warner Hill contains the most 

diverse trilobite assemblage of those samples studied. 

The sample contains Acheilops masonensis Winston 

and Nicholls, "Calvinella" prethoparia Longacre, 

Euptychaspis typicalis Ulrich, Plethopeltis sp. indet., and "Prosaukia" spinula Taylor, n. sp. Sample 

H-1 from Crossman quarry is similar in taxonomic 

composition but lacks Plethopeltis and Acheilops 

masonensis and includes Bowmania cf. B. pennsylvanica Rasetti. Sample 473f, probably collected near 

Crossman quarry, contains Euptychaspis typicalis, 

Plethometopus obtusus Rasetti, Plethometopus sp. 

A, and cf. "Prosaukia" spinula. Locality 470b, from 

the low hill between Skene Mountain and Crossman 

quarry, contains Acheilops masonensis, Euptychaspis sp. indet., and "Prosaukia" spinula. 

Inspection of table 1 shows that samples H-3, 

H-1, 4 73f, and 4 70b are similar in taxonomic composition but are not identical. The geographic 

proximity and taxonomic overlap suggests that differences between localities may reflect only sampling 

differences at approximately the same biostratigraphic horizon. Alternatively, the differences in 

taxonomic composition could reflect differences in 

species range in the local stratigraphic sequence or 

local environment~l factors. The latter alternatives 

cannot be ruled out at p;·esent. 

Sample 418e, from northeast of Whitehall (exact 

locality unknown), contains Stenochilina sp. A, in 

association with the gastropods ?Schizopea sp. and 

Dirachopea sp. Stenochilina was not found in any 

other Whitehall samples, so its occurrence relative to 

other samples cannot be inferred at present. 

Sample 470bl from the hill between Skene Mountain and Crossman quarry and samples 7098-CO 

and 7099-CO from Skene Mountain contain Missisquoia typicalis Shaw. The·se samples all contain 

abundant and abraded trilobite debris, but M. typicalis is the only trilobite taxon recognized. 

Sample H-2 from the southwest side of Warner 

Hill contains Hystricurus millardensis Hintze and 

three specimens questionably assigned to M issisquoia typicalis Shaw. Hystricurus was not recognized in any other Whitehall samples studied. 

GASTROPODS 

Gastropods were not studied in detail. However, 

identifications kindly provided by E. L. Yochelson 

(written commun., Dec. 1971 and Oct. 1972) and 

data on associations are given in table 1. 

OTHER FOSSILS 

Hyolithoids occur rarely in sample H-3, and fragmentary material attributed to M atthevia occurs in 

sample 4 70b. Several bivalved fossils attributed to 

Ribeiria sp. occur in sample 4 70b, and John Poj eta, 

Jr. (oral commun., 1972), identified Ribeiria cf. R. 

nuculitiformis Cleland from sample 7098-CO. These 

fossils were not studied in detail. 

AGE AND CORRELATIONS 

PROBLEMS AND METHODS 

Biostratigraphic studies in the Upper Cambrian 

and Lower Ordovician of Washington County, N.Y., 

are complicated by discontinuous outcrops resulting 

from faulting and by vegetation and soil cover. As 

a result, it is commonly necessary to study fossils 

from isolated exposures or single horizons which are 

difficult to relate to one another. This general problem has been compounded in rocks of latest Cambrian age (Trempealeauan Stage) by the general 

lack of a practicable biostratigraphic scale for subdividing the sequence. Trilobite zonal schemes for 

the type area of the Late Cambrian Trempealeauan 

Stage in the Upper Mississippi .Valley (Howell and 

others, 1944; Raasch, 1951; also see Nelson, 1953) 

have not been successfully applied to other regions 

because oflack of systematic treatment of much of 

the fauna and perhaps because of biofacies 

differences. 

In recent years, research in highly fossiliferous 

sections of latest Cambrian (Trempealeauan Stage) 

and earliest Ordovician carbonate rocks outside the 
BIOSTRAT1GRAPHY 5 

TABLE 1.-The occurrence of identified taxa in samples studied and the inferred biostratigraphic zonal assignment 

[The stratigraphic sequence of samples is inferred from an interpretation of tr:lobite species associations compared with occurrences in other areas (s_ee text). Explana.tion _of s~mbols: ::<, established occurrence, identification definite; cf., established occurrence, identification tentative; ?, esta- blished occurrence, IdentificatiOn questwnable. Mollusks were identified by Ellis L. Yochelson (written commun., December 1971, October 1972] 

Series ---------------------------- Upper Cambrian Lower Ordovician 

Formation ---------------------- Whitehall 

Part ------------ ___ ---- _____ ----- Lower part Upper part 

Zone -----------------------------

Subzone -------------------------

Fossil locality --------------------

Trilobites: 

Acheilops masonensis Winston 

and Nicholls. 

Bowmania cf. B. pennsylvanica 

Rasetti. 

"Calvinella" prethoparia Longacre 

Euptychaspis typicalis Ulrich ----

Euptychaspis sp. indet ----------- Hystricurus millardensis Hintze __ 

Missisquoia typicalis Shaw ------- Plethometopus obtusus Rasetti __ _ 

Plethometopus sp. A ------------- Plethopeltis sp. indet ------------ "Prosaukia" spinula Taylor, n. sp _ 

Stenochil,ina sp. A1 --------------

Gastropods: 

Dirachopea sp ------------------- High-spired gen. and spp. indet __ Low-spired gen. and sp. indet __ _ 

?Lytospira sp ------------------- ?Matherella sp ------------------ "Murchisonia" sp ---------------- Pleurotomariacean gen. indet -----

Schizopea sp. A ----------------- Schizopea sp. B -----------------

?Sinuopea sp -------------------- Other mollusks: 

Hyolithoid ---------------------- Matthevia sp ------------------- Ribeiria cf. R. nuculitiformis 

Cleland. 

Ribeiria sp. indet ----------------

10ccurs in sample 418e, see text. 

Saukiella 

pyrene Saukiella 

iunia 

Not recognized 

Upper Mississippi Valley region has focused on the 

problem of developing a regionally practicable biostratigraphic scheme for correlation. This research, 

largely a result of the efforts of Prof. W. Charles 

Bell and his students, has resulted in a fourfold 

biostratigraphic subdivision of the Trempealeauan 

( =Saukia Zone) based on local ranges and associations of trilobite species in the Wilberns Formation 

of central Texas (Bell and Ellinwood, 1962; Winston 

and Nicholls, 1967). Longacre (1970) refined and 

provided additional information on the Texas fossil 

sequence, and Stitt (1971) established a similar 

zonal scheme for the limestones of the Fort Sill and 

Signal Mountain Formations of south-central Oklahoma. Independent concurrent work by Taylor 

527-763 0 - 7-± - 2 

Saukia M issisquoia 

X 

X 

Saukiella 

serotina 

X 

X 

..Q 

0 

t-

.... 

X 

Corbinia 

apopsis 

Not reco!Plized ... ..Q 

0 

t-

"'<11 

Not established 

0 

0 

I 

"' "' 0 

tI 

0 

0 

I 

00 

0 "' tX X X 

X 

·------- X 

-------- X X X ? 

X 

X 

X 

X X cf. X 

X 

X 

X 

X 

X 

X 

X X 

? X 

X 

X 

X 

X 

? 

X 

X 

X 

X 

X 

X 

( 1971) showed that a similar fourfold subdivision 

of the Saukia Zone can be recognized in the eastcentral Great Basin, and Derby and others (1972) 

have recognized some of the subzones in southern 

Alberta, Canada. 

The Whitehall faunas show a strong biogeographic 

similarity to faunas from Oklahoma, Texas, and the 

Great Basin (discussed under "Biofacies Distribution)." As a consequence, it is possible to infer a 

subzonal assignment for the Whitehall samples by 

comparing taxonomic associations with relative 

ranges of the same taxa in known sequences. The 

relative ranges of Whitehall species that also occur 

in the Great Basin, central Texas, and south-central 

Oklahoma, are given in table 2 as are the ranges of 
6 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

genera common to .. the three regions. 

SAUKIA ZONE 

Relative ranges of species within the Saukia Zone 

as recognized in the Great Basin, central Texas, and 

south-central Oklahoma, provide a basis for inferring the age of the Whitehall trilobites. Inspection of 

table 2 shows that relative ranges of most taxa 

overlap in the Saukiella serotina Subzone of the 

Saukia Zone. The comparison is strongest with sample H-3 from Warner Hill. Samples H-3 and H-1 

could be assigned to the Saukiella junia Subzone, but 

this alternative seems less likely because of the occurrence of ucalvinella" prethoparia, a species apparently restricted to the Saukiella serotina Subzone. 

Inspection of the relative ranges of genera (table 

2) shows that most are too long ranging to be of 

value in subdividing the Saukia Zone. ucalvinella" 

may be an exception, as its known occurrence is restricted to the Saukiella serotina Subzone in these 

areas. However, this apparent restriction is probably a reflection of the occurrence of a group of forms 

similar to "C." prethoparia in the three areas. Calvinella s. l. is a very broadly circumscribed genus 

which needs comprehensive reevaluation before emphasis can be placed on the occurrence of the genus 

alone. (See further discussion under "Systematic 

Descriptions.") 

Sample 418e contains Stenochilina, a genus of 

catillicephalid trilobite that occurs in association 

with Saukia Zone faunas reported from the Conococheague Limestone of Maryland (Rasetti, 1959, p. 

383) and the Eminence Dolomite of southeastern 

Missouri (Ulrich, 1930, p. 215). These occurrences 

establish the Trempealeauan age of the sample, but 

data are insufficient to assign it to a subzone. 

Saukia Zone trilobites have been described and illustrated by Walcott (1879, 1912b) from the Hoyt 

Limestone near Saratoga Springs, N.Y. Some additional Late Cambrian fossils from the Saratoga 

Springs area were illustrated by Rasetti (1946) and 

by Fisher and Hanson (1951). Our Late Cambrian 

collections from the Whitehall Formation were compared with the material in the U.S. National Museum collections studied by Walcott ( 1912b). The 

examination showed that available collections from 

the two areas contain no trilobite species in common. 

The mollusks reported by Walcott (1912b) from the 

Hoyt include species of Triblidium, JU atherella, 

M atthevia, and Pelagiella. Of these molluscan taxa, 

only M atthevia and one specimen questionably assigned to M atherella were recognized in the Whitehall samples studied. 

The Hoyt fauna from Saratoga County, N.Y., contains trilobite forms that do not occur in the described faunas from Oklahoma, Texas, or the Great 

Basin. As a result, it is not now possible to assign 

the Hoyt fauna to any of the subzones of the Saukia 

Zone. Therefore, although faunas from the Hoyt 

Limestone and lower Whitehall Formation can be 

assigned to the Trempealeauan Stage, it is not yet 

possible to document on paleontological evidence 

which parts of these two formations are 

synchronous. 

Lochman (1946) described and illustrated Prosaukia briarcliffensis and Plethometopus knopfi 

from the Briarcliff Dolomite near Pine Plains in 

Dutchess County, N.Y. The fauna can be assigned to 

the Saukia Zone, but further refinement in classification cannot be made at present. 

Dwight (1886a, b; 1887) reported a rich collection of trilobites from outcrops near Poughkeepsie, 

Dutchess County, N.Y., which he (1887, p. 208) 

correlated with the Hoyt fauna at Saratoga Springs 

(then called "Potsdam limestone"). Apparently the 

Poughkeepsie fauna has been neither described nor 

illustrated so that further comparison cannot be 

made at present. 

Bird and Rasetti (1968) listed several occurrences 

of probable Trempealeauan fossils from the Taconic 

sequence of Columbia County, eastern New York 

State. Examination of the material showed that the 

collections contain no genera or species in common 

with the Whitehall fauna. The Taconic localities contain genera typical of the Hungaia magnifica fauna 

(Bird and Rasetti, 1968, p. 45), but the full significance of the occurrences must await formal description of the fossils. 

MISSISQUOIA ZONE 

Sample 470b11 from the low hill between Skene 

Mountain and Crossman quarry, samples 7098-CO 

and 7099-CO from the upper part of the Whitehall 

Formation on Skene Mountain, and questionably 

sample H-2 from Warner Hill, contain Missisquoia 

typicalis Shaw in association with abundant gastropods. (See table 1.) Missisquoia typicalis was originally described from the Highgate Formation of 

northwestern Vermont (Shaw, 1951, 1955, 1958). 

Subsequently, the species was reported from the 
BIOSTRATIGRAPHY 7 

TABLE 2.-Comparison of the biostratigraphic ranges of trilobite species and genera from the Whitehall Formation with 

occurrences in the central Great Basin, central Texas, and south-central Oklahoma 

[No attempt has been made to depict differences between regioJU> in local range within Cambrian subzones or Early Ordovician zones] 

Explan'ation of symbols: E9 Great Basin (Hintze, 1952; Taylor 1971. * Centra.! Texas (Winston and Nicholls, 1967; Longacre, 1970). C South-central Oklahoma (Stitt, 1971). 

Epoch ---------------------------

Zone ______ --- _ -------------------

Subzone -------------------------

Species: 

Acheilops masonensis Winston and Nicholls 

Bowmania pennsylvanica Rasetti ------------------

"Calvinella" prethoparia Longacre ----------------

Euptychaspis typicalis Ulrich --------------------

Hystricurus millardensis Hintze -------------------

Missisquoia typicalis Shaw ------------------------

Plethometopus obtusus Rasetti --------------------

Plethometopus sp. A -----------------------------

"Prosaukia" spinula Taylor, n. sp ----------------

Stenochilina sp. A ------------------------------

Gener~ 

Acheilops Ulrich _______________________________ _ 

Bowmania Walcott ------------------------------

"Calvinella" Walcott 

Euptychaspis Ulrich -----------------------------

Hystricurus Raymond 

Missisquoia Shaw -------------------------------

Plethometopus Ulrich 

Plethopeltis Raymond _________________ --______ ---

"Prosaukia" Ulrich and Resser -------------------

Stenochilina Ulrich 

1 Also reported in pre-Saukiclla pyrene beds. 

Wilberns Formation of central Texas (Winston and 

Nicholls, 1967). Winston and Nicholls (p. 72) 

showed that part of the Wilberns Formation contains an assemblage of trilobites consisting of species 

of Homagnostus, Hystricurus, Symphysurina, Highgatella, Missisquoia, and Parabolinella. The association, named the Missisquoia Zone, occurs stratigraphically between faunas characteristic of the 

Late Cambrian Early Ordovician 

SymphySaukia Missi8quoia surina B 

Saukiella Saukiella Saukiella Corbinia pyrene junia serotina apopsi8 Not established 

E9 

* * 0 0 

E9 

0 0 * 0 0 

* E9 E9 

* 0 0 

E9 

* 0 

E9 

* 0 

* * 0 0 

E9 E9 E9 

0 0 * * 

? E9 E9 

0 0 * 0 0 

E9 

* 0 

EB E9 (f) 

* * 0 0 * 

(f) (f) 

* * 0 

E9 

0 * 

? E9 EB 

* * * 0 * 0 0 

* E9 E9 0 

E9 1* 

0 

subjacent Corbinia apopsis Subzone of the Saukia 

Zone and a superjacent zone consisting of an association of species of Clelandia, Hystricurus, Jujuyaspis, 

Homagnostus, and Symphysurina. Winston and 

Nicholls (1967) considered the latter association 

most similar to the Symphysurina B Zone of Ross 

(1951) and Hintze (1952). 

N orford ( 1969) reviewed the known distribution 
8 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

of some Early Ordovician trilobites in North America and concluded that the Missisquoia and Symphysurina Zones of Winston and Nicholls (1967) together probably represent Zone A of Ross (1951). 

Evidence for this interpretation is the reported occurrence of Hystricurus cf. H. sp. D of Ross in both 

the Missisquoia and Symphysurina zones of Winston 

and Nicholls. H ystricurus sp. D of Ross is otherwise known from Zone A of Ross (1951, p. 29) near 

the base of the Garden City Formation in southeastern Idaho. This evidence is considered tenuous, 

and we prefer to recognize the Missisquoia Zone as 

originally defined by Winston and Nicholls (1967). 

Stitt (1971) studied the biostratigraphy of Late 

Cambrian and Early Ordovician trilobites in the 

western Arbuckle Mountains of south-central Oklahoma. He reported a trilobite association that includes species of Hystricurus, Symphysurina, Missisquoia (including M. typicalis), Apoplanias, 

Homagnostus, and Plethopeltis, which he assigned 

to the Missisquoia Zone. The Mi.~sisquoia Zone assemblage occurs in the Signal Mountain Limestone· 

where it is underlain by assemblages assigned to the 

Corbinia apopsis Subzone. Beds immediately above 

the M issisquoia Zone are only sparsely fossiliferous, 

so that the top of the zone is poorly defined in 

Oklahoma. 

The Missisquoia Zone also occurs in the uppermost 

part of the Notch Peak Limestone in the southern 

House Range of west-central Utah (Taylor, unpub. 

data, 1971) . The Notch Peak contains an association of species of Highgatella, Hystricurus, JJ!issisquoia (including M. typicalis), and Symphysurina, 

which overlies Corbinia apopsis Subzone assemblages. The Notch Peak Limestone is conformably 

overlain by the House Limestone, in the lower part 

of which Hintze (1952) originally established the 

presence of the Symphysurina B Zone in western 

Utah. 

Derby, Lane, and Norford (1972) reported a 

Missisquoia Zone fauna from the Survey Peak Formation in the southern Rocky Mountains of Alberta. 

The listed fauna contains species of Apoplanias, 

Missisquoia (tentatively referred to M. typicalis), 

Highgatella, and a large number of nontrilobite taxa. 

Derby, Lane, and Norford (1972) redefined the 

Missisquoia Zone to coincide with the biostratigraphic interval between the first occurrence of 

Apoplanias and the first occurrence of Symphysurina 

in the Survey Peak Formation. The regional practicability of this redefinition remains to be proved 

because: ( 1) species of Symphysurina seem to occur 

earlier in central Texas and south-central Oklahoma 

in association with Missisquoia typicalis, and (2) 

Lochman and Wilson (1967, p. 893) reported that 

an undescribed species of Apoplanias may be present in association with Saukia Zone assemblages in 

central Montana. 

In summary, the known biostratigraphic occurrences of M issisquoia typicalis are restricted to the 

Missisquoia Zone as originally defined in North 

America. The upper Whitehall occurrences are tentatively assigned to the zone on this basis. 

SYMPHYSURINA B ZONE(?) 

Sample H-2 from the upper part of the Whitehall 

Formation at Warner Hill contains H ystricurus 

millardensis Hintze, Missisquoia typicalis Shaw ( ?) , 

and several poorly preserved gastropods. Hystricurus millardensis was originally reported from the 

Symphysurina B Zone in the southern House Range 

area of west-central Utah (Hintze, 1952). Subsequently, the species was recognized in the Symphysurina Zone of central Texas (Winston and Nicholls, 

1967) and south-central Oklahoma (Stitt, 1971). 

This apparent restriction of H. millardensis to the 

Symphysurina B Zone provides limited evidence for 

inferred presence of the zone in the upper part of the 

Whitehall Formation. Alternatively, the absence of 

Symphysurina and presence of Missisquoia typicalis ( ?) in sample H-2 is suggestive of the Missisquoia Zone. Sample H-2 is tentatively assigned to 

the Missisquoia Zone for this reason, although further collecting at Warner Hill is necessary to verify 

the zonal assignment. 

CAMBRIAN -ORDOVICIAN BOUNDARY 

The base of the Ordovician System in North 

America has been traditionally recognized by the 

lowest occurrence of Symphysurina (Ross, 1951; 

Hintze, 1952; Bell and others, 1956; Palmer, 1971a; 

Lochman, 1971), even though the position of the 

boundary probably differs from that in the classic 

areas of Europe (Whittington and Williams, 1964; 

Whittington, 1966). The M1:ssisquoia Zone contains 

the earliest known occurrence of Symphysurina in 

North America (Winston and Nicholls, 1967; Stitt, 

1971; Taylor, 1971), although not at the base (Derby and others, 1972), and is therefore tentatively 

accepted here as the earliest trilobite assemblage 

zone of the Ordovician System in North America. As 

so recognized, the Cambrian-Ordovician boundary 

falls within the Whitehall Formation in Washington 
ENVIRONMENTAL SETTING 9 

County, N.Y. (Fisher, 1968, 1969), rather than at 

the base (Rodgers, 1937; Fisher, 1962) or top 

(Wheeler, 1942; Flower, 1964) of the formation, as 

had previously been thought. Available biostratigraphic data are not sufficiently refined at present 

to determine how closely the boundary between lower 

and upper parts of the formation approximates the 

systemic boundary. 

SUMMARY 

The age of fossil samples from the Whitehall Formation in eastern New York is inferred from the 

known range of species in biostratigraphic sequences in other areas. On this basis, samples can 

be grouped into two taxonomic assemblages. The 

older assemblage from the lower part of the Whitehall is assigned to the Saulciella serotina Subzone of 

the Late Cambrian Saulcia Zone, and the younger assemblage from the upper part of the Whitehall is 

assigned to the earliest Ordovician Missisquoia Zone. 

The Corbinia apopsis Subzone, which normally occurs between the Saulciella serotina Subzone and 

Missisquoia Zone, has not yet been recognized in 

New York State. Biostratigraphic classification of 

the Whitehall fossil samples is shown in table 1. 

ENVIRONMENTAL SETTING 

Fossils described in this paper were collected from 

limestones within the Whitehall Formation or from 

loose blocks presumed to be derived from the Whitehall. The fossils mostly occur as poorly sorted bioclastic debris in beds composed of ooid-skeletal lime 

grainstone. All fossils studied represent vagile epibenthos that were presumably highly susceptible to 

post-mortem transport and mixing that could potentially obscure original natural spatial relationships 

between organisms and environments. The fragmented condition of most trilobite exuviae is usually 

evidence that some mechanical degradation occurred 

before burial. However, the very poor sorting and 

common association of a wide variety of grain 

shapes with presumably different hydrodynamic 

properties suggests that distances of post-mortem 

transport were probably short, perhaps on the order 

of tens of feet rather than thousands of feet or miles. 

This conclusion is consistent with the findings of 

Ginsberg (1956), who showed that the bulk of skeletal carbonate grains in the Florida reef tract coarser 

than one-eight of a millimeter accumulate in the subenvironment in which the grains originate. The fact 

that taxonomic associations similar to those in the 

Whitehall can be recognized in widely scattered 

parts of North America (see "Biofacies Distribution") adds credence to the interpretation that fossils were not transported great distances before 

burial. (Also see Mudge and Yochelson, 1962, p. 

108.) Such recurrent associations of vagile epibenthic taxa may be considered parautochthonous faunules. However, the inferred correlation between a 

particular faunule and a particular environment 

should be accepted only cautiously because of the 

possibility that bioclastic debris accumulated near, 

but not necessarily in, the precise microenvironment 

occupied by the living organisms. 

In spite of the tenebrous influence of biostratinomic factors, the fossil-enclosing rocks are thought 

to contain the best independent evidence currently 

available for deducing the physical environment occupied by the fossils. Comparisons can be made between observed depositional features of the Whitehall and those of recent and other ancient carbonate 

sediments and rocks to provide a basis for inferences concerning some aspects of the environment in 

which the Whitehall organisms lived. Thus, here we 

review those aspects of the limestones, based on 

Halley's (1971a) detailed study, which might have 

particular relevance to the environmental setting of 

the Whitehall fauna, rather than present a detailed petrographic description of the Whitehall 

Formation. 

PETROLOGY 

The bulk of the limestones examined from the 

Whitehall consist of grainstones and boundstones (in 

the carbonate rock classification of Dunham, 1962). 

These are the predominant lithologies of the exposures at Crossman quarry (fig. 2), the upper 

slopes of Warner Hill, Skene Mountain, and Tub 

Mountain. (See fig. 1.) Constituent particles of the 

grainstones in order of decreasing abundance are 

ooids, lithoclasts, pelletoidal grains, quartz grains, 

and trilobite and gastropod fragments. (See pl. 4.) 

Chert, length-slow chalcedony, pyrite, dolomite, and 

chlorite are minor (less than 1 percent) diagenetic 

minerals present. The Whitehall grainstones occur 

as individual beds or as fill betw2en boundstone 

structures (fig. 3). Beds composed entirely of grainstone are 2-24 inches thick, uniform in thickness for 

the length of outcrop (as much as 100 yards), and 

often have either low-angle crossbedding or planar 

bedding. 

Boundstones of the Whitehall Formation are 

thought to be cryptalgal structures (Aitken, 1967; 

Halley, 1971b) formed by the sediment-binding and 
10 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

... (\ . {\ 

·r.·:· 'Q.' 'l(, • • •• 

• •• Q. .·,..., •• 

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• ;, .. .. • • 0 ~ 0 

• • 0 

0 0 • • •• 

• • • 0 • 0 •• 0 

•• 0 • • 0 • 

• . . r'\ • 

EXPLANATION 

LIMESTONE COMPONENTS 

I "n" I SKELETAL GRAINS 

~OOIDS 

D PELLETS AND LITHOCLASTS 

~ QUARTZ SAND GRAINS 

~ CHERT AND CHALCEDONY 

STROMATOLITES 

I6P3I THROMBOLITES 

. o:Q. o~Q· 

~ ·. · r"\ · · . · __._Fossil locality H-1 

• 

0 .6. . • • .' 

0 

. • t 2

0 

FEET 

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.. 

0 

FIGURE 2.-Columnar section showing typical repetition of 

components in limestones of the lower Whitehall Formation, exposed on the east •side of Crossman quarry 8-20 

feet above the quarry floor. Photomicrographs of thin 

sections showing .the various lithic types are given on 

plate 4, figures 1- 6. 

(or) carbonate-precipitating activities of nonskeletal algae. Domal stromatolites are cryptalgal structures characterized by convex-upward laminations. 

Layers within the Whitehall domal stromatolites 

have a clastic texture, and the laminated fabric is 

produced by variations in grain size (pl. 4, fig. 6). 

Relief of Whitehall stromatolites ranges from 0 to 

18 inches, as evidenced by tracing single laminations 

around the structures (fig. 4). 

Two distinctly different types of nonlaminated 

cryptalgal structures (thrombolites of Aitken, 1967) 

occur in the Whitehall. The most common type forms 

both beds and individual mound structures with as 

much as 12 inches of surface relief (fig. 5). Fabric 

observed in outcrop appears clotted whereas in thin 

section the texture is clastic with clots formed by 

variations in grain packing. Clots that appear light 

gray in outcrop are grain supported; darker clots 

are spar rich and are not grain supported (pl. 4, 

fig. 5). The second type of nonlaminated cryptalgal 

structure consists of lime mudstone mounds without 

clastic textures. These structures are less common 

and also have clotted fabric. However, the light-gray 

clots in mudstone mounds are internally grain-filled 

fenestrae as much as 1 inch long in the largest dimension. Some fenestrae have spar-filled geopetal 

surfaces (pl. 4, fig. 4). The matrix of nonlaminated 

mounds is finely crystalline to aphanocrystalline, 

dark gray to black, the finer grained patches being 

darker in color value. Individual grains are rarely 

recognized in lime mudstone mounds outside of the 

grain-filled fenestrae. 

The Whitehall grainstones and three types of 

boundstones recur vertically in beds a few inches to 

several feet thick (fig. 2). This phenomenon was 

interpreted (Halley, 197la) to have been produced 

by oscillations of the strandline. 

INFERRED ENVIRONMENTS 

The depositional environments of the Whitehall 

Formation may be inferred from comparisons with 

recent and ancient carbonate deposits. Domal highrelief stromatolites have been reported forming today in the intertidal zone of Hamelin Pool, a 

hypersaline lagoon in Shark Bay, Western Australia 

(Logan, 1961; Logan and others, 1964; Davies, 

1970). Surface relief of the Shark Bay algal stromatolites has been correlated with water turbulance. 

High-relief forms are typical in the low intertidal 

zone of exposed headlands, whereas low-relief forms 

FIGURE 3.- Sharp vertical contact between lo•w-angle crossbedded grainstone to the left, and finer grained clotted 

thrombolil!ic fabric to the right. Lower Whitehall Formation, Crossman quarr y. Lens 0ap is 3 inches (7.5 em) in 

diameter. 
ENVIRONMENTAL SETTING 11 

FIGURE 4.-Domal stromatolites in the lower part of the 

Whitehall Formation, Crossman quarry. Relief on these 

particular forms decreases upward so that the upper 

few inches are nearly fl·at laminated. Lens cap is 3 inches 

(7.5 em) in diameter. 

and flat-laminated sediments (incipient cryptalgalaminates) occur in high-intertidal and supratidal 

sites and on tidal flats along protected shorelines 

(Logan, 1961, p. 529; Hoffman and others, 1969; 

Davies, 1970, p. 181). Low-relief stromatolites and 

flat-laminated sediments also characterize the high 

intertidal zone of south Florida (Ginsburg and others, 1954; Gebelein and Hoffman, 1969); Andros 

Island, Bahamas (Shinn and others, 1969, p. 1211-

1216) ; and the Abu Dhabi along the Persian Gulf 

(Kendall and Skipwith, 1968). These features, when 

recognized in ancient rocks, can be used to infer 

near-sea-level or tidal-flat deposition. Many modern 

studies have successfully applied these modern analogues to the interpretation of ancient carbonate environments (for example, Roehl, 1967; Laporte, 

1967). By analogy with recent patterns of occurrence, stromatolites and cryptalgalaminates in the 

lower part of the Whitehall Formation are inferred 

to have formed under conditions of tidal-flat 

deposition. 

Recent carbonate fabrics analogous to thrombolites have not been reported. However, Aitken (1967, 

p. 1176) inferred from studies in Cambrian and 

Ordovician rocks of Alberta that thrombolites may 

have formed in low intertidal and shallow subtidal 

sites, possibly under hypersaline conditions. 

Low-angle and planar crossbedded carbonate 

sands are characteristically found in low intertidal 

and shallow subtidal sites in the Bahamas (Imbrie 

and Buchanan, 1965). In the Whitehall, the association of pellet and ooid grainstone around the bases 

of stromatolites suggests deposition in a relatively 

high-energy, low intertidal environment. Occasionally, crossbed sets of grainstone, which overlie 

stromatolites, dip in opposite directions, and the 

resulting "herringbone" fabric is thought to be 

typical of shallow subtidal and low intertidal sites 

of deposition (Klein, 1972, p. 400). 

Oolite and other mud-free grainstones indicate 

sustained moderate to high turbulence in warm and 

probably clear water. Ooid formation requires frequent agitation of the sand-sized grains, and other 

spar-rich grain-supported rocks suggest that mud 

was winnowed from the sediment by frequent agitation. Evidence was not found for diagenetic alteration (neomorphism) of micrite to pseudospar in the 

thin sections and acetate peels made of Whitehall 

limestones (Halley, 1971a). 

Hypersalinity or highly fluctuating salinity in the 

Whitehall depositional environment may be suggested by the abundance of high-relief domal 

stromatolites and by the presence of length-slow 

chalcedony. Recent high-relief domal stromatolites 

are uniquely associated with hypersaline environments in Shark Bay, Western Australia (Logan, 

1961, p. 518; Hoffman and others, 1969; also compare Logan and others, 1970, fig. 7B; Logan and 

Cebulski, 1970, fig. 6). 

Folk and Pittman (1971) recently presented 

strong evidence that length-slow chalcedony forms 

FIGURE 5.-Domal thrombolite in the lower Whitehall Formation, Crossman quarry. A 6-inch-long (15 em) pen 

placed in the lower right corner of photograph is at the 

contact between a thrombolite (left) and planar-bedded 

grains.tone (right). Dark material is chert. 
12 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

predominantly in association with evaporitic deposits. The relatively low solubility and persistence 

of length-slow chalcedony in carbonate deposits that 

lack more obvious evidence for evaporites suggest 

that occurrence of the mineral may be used as an 

indicator of evaporitic conditions. Length-slow chalcedony occurs in the Whitehall Formation as void fill 

within some fenestrae of nonelastic thrombolites (pl. 

4, fig. 3) and as cements in some grainstones. However, the time of emplacement of the Whitehall chalcedony is unknown so that it is not now possible to 

differentiate between an early diagenetic origin in 

contact with primary hypersaline marine waters, or 

late diagenetic origin from hypersaline waters 

flushed through the Whitehall beds from other 

evaporitic horizons. 

It may be noteworthy however, that almost half 

the examples of length-slow chalcedony cited by 

Folk and Pittman (1971, p. 1052-1053) are from 

Cambrian and Ordovician carbonate rocks, many of 

which are stromatolitic. Thus, the association of 

domal stromatolites and length-slow chalcedony in 

the Whitehall Formation may be tentatively accepted 

as evidence of hypersaline conditions. Absence of 

remains of infaunal organisms and echinoderms 

from the Whitehall rocks is consistent with hypersaline conditions in the depositional environment. 

The geographic setting of the Whitehall cryptalgal 

limestones was probably the inner, landward (eratonal) side of the carbonate shelf. (See "Biofacies 

Distribution.") Shoreline deposits of the Whitehall 

are associated with well-rounded quartz sand grains. 

The quartz grains are diagenetically etched, and 

parts of the grain edges have been replaced by calcite. Diagenetic alteration of grain surfaces precludes an interpretation of the transport mode of 

these grains (Margolis, 1968, p. 255). However, the 

presence of quartz sand in the Whitehall indicates 

that these deposits were not isolated from a clastic 

source, here probably the exposed craton. The quartz 

sand suggests that Whitehall shorelines were probably near the exposed cratonal margin rather than on 

carbonate islands which may have existed near the 

outer edge of the shelf. Field evidence for the width 

of the Whitehall carbonate shelf is inconclusive because the seaward edge is obscured by the allochthonous Taconic sequence a few miles east of the 

study area (Theokritoff, 1964; fig. 1, this report). 

The frequency with which evidence of shorelines 

is found in the Whitehall sections indicates that the 

contained faunas probably lived relatively near 

shore. No fossils were found uniquely associated 

with intertidal lithologies, and it is thus presumed 

that the animals lived in nearby shallow subtidal 

habitats. 

In summary, the Whitehall fossils represent a 

vagile epibenthic fauna that probably lived in a 

nearshore subtidal habitat characterized by warm 

and clear marine waters. The habitat probably experienced sustained moderate to high turbulence and 

may have had a high range of salinity or generally 

hypersaline conditions. The geographic site of deposition was probably on the landward edge of a 

carbonate shelf of unknown width. 

BIOFACIES DISTRIBUTION 

MODELS 

Two major facies models have been proposed to 

explain the distribution of North American Cambrian trilobite faunas. The first was presented by 

Lochman and Wilson (1958) who recognized three 

biofacies "realms" which were thought to be concentrically arranged around the North American 

craton and tectonically controlled. Lochman (1970, 

1971) recently reviewed and updated the earlier 

model for part of the North American area. In the 

latter studies, Lochman recognized two major biofacies: (1) A "cratonic" biofacies, consisting of 

"Pacific province" assemblages occurring in cratonal 

and miogeosynclinal sites, and (2) an "extracratonic" biofacies, consisting of "Atlantic province" 

assemblages which occur in outer miogeosynclinal 

and eugeosynclinal areas. The Whitehall Saukia 

Zone fauna is near the outer limits of the cratonic 

biofacies as interpreted by Lochman (1970, fig. 7) 

for New York State. 

Palmer (1960, 1965, 1968, 1969, 1971a, b, 1972a, 

1973) has developed a second model of Cambrian 

trilobite- and sediment-distribution patterns that is 

based on the recognition of three more or less coincident biofacies and lithofacies belts concentrically 

arranged around the North American craton. The 

model differs from that of Lochman and Wilson by 

placing greater emphasis on sedimentary depositional patterns and contained fossils, rather than on geotectonic criteria. Palmer's lithofacies belts have been 

termed: (1) an "inner detrital belt," characterized 

by terrigenous clastic rocks dominated by quartzose 

and feldspathic sandstone, glauconitic sandstone, 

and varying amounts of shale and carbonate rocks, 

(2) a "carbonate belt" characterized by generally 

high-mechanical-energy coarse-textured bioclastic 

sparry limestones, oolitic and pisolitic limestones, 
BIOFACIES DISTRIBUTION 13 

high-relief stromatolites, massive accumulations of 

light-colored lime mudstone and dolomite, and (3) 

an "outer detrital belt" characterized by darkcolored shales, siltstones, and intercalated thinly 

bedded limestones which are commonly pyritic and 

carbonaceous. Each lithofacies belt has been postulated to contain a particular trilobite fauna characterized by differences in relative abundance and particular associations of genera and species (Palmer, 

1968, 1969). The model reflects a broad shallowwater depositional shelf with inner-shelf terrigenous 

clastic environments grading seaward to outer-shelf 

carbonate shoals and tidal flats, which in turn grade 

oceanward to basinal (below maximum effective 

wave base) sedimentary environments. 

Palmer's model seems to have greater heuristic 

value than the earlier model (Lochman and Wilson, 

1958; Lochman, 1970, 1971) for several reasons: 

(1) The model separates rocks and contained faunas 

from the a priori genetic implications of the geotectonic categories "cratonal shelf," "miogeosyncline," 

and "eugeosyncline." The sedimentary model implies a more or less continuous transition of environments from shoreline to continental shelf margin, 

rather than a sharp division into cratonal and miogeosynclinal sedimentary environments. Sloss 

(1960) has stressed the similarity of early Paleozoic sedimentary sequences in cratonal and miogeosynclinal sites in the Western United States, and 

data presented by Lochman (1971, figs. 21-24) show 

that Trempealeauan sedimentary facies patterns are 

not closely correlated with geosynclinal areas, (2) 

the model can be applied to critical analyses of the 

relative influence of eustatic and epeirogenetic 

factors in the regional control of lithofacies distribution, and (3) the model is more reflective of inferred Cambrian paleogeography and thus is more easily compared with recent geographic conditions. 

Therefore, it may provide a regional framework for 

studies of paleoecology, adaptive radiation in space 

and time, and more detailed analyses of the significance of biogeographic distribution patterns. 

METHODS OF ANALYSIS 

An historically meaningful biogeographic (biofacies) analysis ideally should be based on critically 

studied taxa to insure that concepts of all operational taxonomic units are consistently applied 

throughout the area to be analyzed. The present state 

of knowledge of North American Saukia Zone trilobite faunas falls short of this ideal. Taxonomic data 

527-763 0 - 74 - 3 

are unevenly developed. Some areas have been subjected to intensive collecting and systematic study 

(for example, central Texas and Oklahoma), whereas some other areas have a variety of problems, such 

as relatively incomplete systematic study (for example, Upper Mississippi Valley) and early systematic work that needs reevaluation (for example, 

New Jersey and, in part, Vermont) ; in some areas, 

faunas are known only from lists (for example, 

Taconic sequence of New York and western Newfoundland). These factors limit the reliance that can 

be placed on numerical analyses of biogeographic 

distribution patterns. However, it seems useful to 

examine distribution patterns, even though possible 

interpretation is limited at present. 

Simpson's (1960, p. 301) index of faunal resemblance ( IFR) is used here to determine the degree 

of apparent biofacies similarity between the Saukia 

Zone trilobite fauna at Whitehall and at other North 

American sites (fig. 6). IFR is calculated from the 

equation IFR=C/NX100, where C equals the number of taxa in common between two samples and N 

equals the number of taxa in the smaller of two samples. IFR values were calculated for both species and 

genera that occur at Whitehall. Results are shown 

in tables 3 and 4. 

Simpson (1960) has discussed the advantages and 

disadvantages of his index in paleontological studies 

and Mello and Buzas (1968), and Cheetham and 

Hazel (1969) have compared the index with other 

numerical indexes. In general, IFR minimizes effects of differences in sample size (Simpson, 1960, 

p. 301) and tends to emphasize similarity (Cheetham and Hazel, 1969, p. 1135). IFR can become 

strongly biased when large discrepancies exist in 

sample size. When the number of taxa in the smaller 

sample (N) approaches the number in common (C) 

between two samples, excessively high IFR values 

result. However, calculated values provide an objective and explicit basis for discussion of regional 

faunal similarities if limitations are recognized and 

differences in IFR are cautiously interpreted. 

ASSEMBLAGES SIMILAR TO WHITEHALL FAUNA 

Analysis of species-level faunal resemblance with 

the Whitehall Saukia Zone fauna shows a range in 

IFR values from 25 to 63 for the east-central Great 

Basin (Notch Peak and Whipple Cave Formations), 

Llano region of central Texas (Wilberns Formation), Arbuckle Mountains of Oklahoma (Signal 

Mountain Formation), and the central Appalachian 
14 L·ATE GAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

Ciao 

----l 

I 

I 

\ 

\ 

I 

I 

.r---. 

'•2 

0 200 400 600 800 1000 MILES 

0 200 400 600 800 1000 KILOMETERS 

0 

(\J 0 

-r-·----~----·- i I 

I I 

I ! 

I ! I 

EXPLANATION 

.A Basinal facies (outer detrital belt) 

e Outer-shelf facies (carbonate belt) 

X Inner- shelf facies (inner detrital belt) 
BIOFACIES DISTRIBUTION 15 

region ( Conococheague Limestone) . Faunal resemblance at the generic level shows an increase in degree of similarity ranging from 63 to 87 for the 

same areas; high resemblance is also shown with the 

fauna of the Mount Wilson area of Alberta (Mistaya and Survey Peak formations), the Eminence 

region (Eminence Dolomite) of Missouri, the Upper 

Mississippi Valley (Trempealeauan Stage), and perhaps northwestern New Jersey (Kittatinny Limestone). 

Lithologic analysis of containing rocks provides 

evidence for the existence of a shallow-water carbonate bank in some of those areas showing high IFR 

values with the Whitehall Saukia Zone fauna. 

Studies of Upper Cambrian rocks in the Mount Wilson area of Alberta (Aitken and N orford, 1967; 

Aitken, 1967) and in central Texas (Ahr, 1971) 

show that in those areas the Saukia Zone interval 

is characterized by coarse-textured skeletal grainstones, oolitic and pisolitic grainstones, flat-pebble 

conglomerates, and both laminar and nonlaminar 

algal boundstones. The characteristics of these diverse rock suites are consistent with those here described for the Whitehall Formation and are thought 

to reflect origin in shallow subtidal to tidal-flat 

environments. (See, for example, Laporte, 1971.) 

Detailed petrographic studies have not been made ' 

in the other areas. However, field studies of strata 

containing the Saukia Zone fauna in th9 east-central 

Great Basin (Taylor, 1969, 1971) report an abundance of flat-pebble conglomerate, skeletal and oolitic 

grainstones, and laminar and nonlaminar limestone 

mounds that may prove similar to those described by 

Aitken (1967) from Alb9rta and Ahr (1971) from 

central Texas. Stitt (1971) reported similar rock 

types in the Signal Mountain Limestone of southcentral Oklahoma, and the Conococheague Limestone 

has been characterized (Wilson, 1952; Sando, 1957) 

FIGURE 6.-Map showing the general location of principal 

areas of North America from which Saukia Zone faunas 

have been reported. See text for discussion. Sources of 

data: (1) East-central Alaska (Palmer, 1968); (2) Mount 

Wilson, Alberta (Derby and others, 1972); (3) McCone 

County, Mont. (Lachman, 1964a); (4) southwestern Montana (Grant, 1965); (5) central Nevada and (6) eastern 

Nevada-western Utah (Taylor, 1971); (7) Marathon basin, 

Texas (Wilson, 1954, 1956); (8) Oaxaca, Mexico (Robison 

and Pantoja-Alor, 1968); (9) Llano uplift, Texas (Longacre, 1970); (10) Arbuckle Mountains, Okla. (Stitt, 1971); 

(11) Eminence region Missouri (Ulrich, 1930); (12) 

Upper Mississippi Valley (Nelson, 1951; Raasch, 1951) ; 

as commonly containing oolites, flat-pebble conglomerates and "cryptozoan" beds. Detailed data on the 

fauna and lithologic characteristics of the Kittatinny Limestone of New Jersey are few so that 

further study is needed to clarify the faunal and 

environmental relationships with other Upper Cambrian sites. 

The widespread distribution, high degree of faunal similarity, and association with grossly similar 

sedimentary environments suggests that the Whitehall Saukia Zone fauna is part of a near-sea-level 

shelf carbonate biofacies that seems to be oriented 

concentrically around the North American Late 

Cambrian cratonal region. 

The Saukia Zone fauna from the Upper Mississippi Valley area shows a high degree of generic-level 

similarity (IFR = 87) with the carbonate shelf biofacies typified by the Whitehall fauna, even though 

terrigenous clastic deposition dominates that area 

(Nelson, 1956; Lochman, 1971). Such a high degree 

of faunal similarity is inconsistent with the Palmer 

model of distinct inner detrital belt and carbonate 

belt biofacies. The discrepancy cannot be critically 

evaluated at present because taxonomic information 

on the Upper Mississippi Valley Trempealeauan 

fauna is available only for the relatively large trilobites of the families Dikelocephalinae and Saukiinae, 

whereas the presence of most other taxa are only 

known from faunal lists (Nelson, 1951; Raasch, 

1951). On the other hand, the low IFR value between Whitehall (carbonate shelf facies) and northeastern and southwestern Montana (Lochman, 

1964a; Grant, 1965) (detrital shelf facies) suggests 

that some faunal differences may be present between 

these two areas. Further taxonomic work is needed 

to elucidate biofacies differences and similarities between outer and inner shelf sites during Trempealeauan time. 

(13) central Appalachian Mountains, Conococheague Formation, and (14) central Appalachian Mountains, Frederick and Grove Formations (Rasetti, 1959); (15) northwestern New Jersey (Howell, 1945) and observations, this 

report; (16) Taconic sequence, eastern New York State 

(Bird and Rasetti, 1968); (17) Saratoga Springs, N.Y. 

(Walcott, 1912b), and observations, this report; (18) 

Whitehall, N.Y., this report; (19) St. Albans area, Vermont (Raymond, 1924, 1937; Clark and Shaw, 1968), and 

some taxonomic reassignments, this report; (20) Levis 

area, Quebec (Rasetti, 1944, 1945, 1963); (21) Broom 

Point, western Newfoundland (Kindle and Whittington, 

1959). 
16 LATE CAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

TABLE 3.-Known occurrences of trilobite species rec.ognized from the Saukia Zone at Whitehall, N.Y. 

[Simpson's (1960) index of 

and other 

faunal resemblance (IFR) is a rough measure of the degree of apparent biogeographic similarity between Whitehall areas where the species are known. Data-source numbers in parentheses are explained in 6. lished occurrence; -, not known to occur; fig. Explanation of symbols: x. estab-

?, questionable identification; *, insufficient data for computation. See text for discussion of each area] 

C"' ~ '<!' 

.a ,.3 ell Area ...... = = ell t 0 .., "' ,..Q ::a s:: ~ 0 lll < ~ ::a ~ = s:: s:: ~ ~ "" ri 0 $ 

~ Ql 0 gj "" "' Ql 

.., !it Ql § s:: -E ~ ~ 0 ~ 

"' 0 (.) 0 

r.:1 ::a ::a rJJ 

Acheilops masonensis Winston and Nicholls __ 

Bowmania cf. B. pennsylvanica Rasetti ------

"Calvinella" prethoparia Longacre ---------- Euptychaspis typical is Ulrich -------------- - Plethometopus obtusus Rasetti ------------- Plethometopus sp. A ---------------------- "Prosaukia" spinula Taylor, n. sp ---------- Stenochilina sp. A ------------------------

Index of faunal resemblance (IFR) 0 * 0 --------

ASSEMBLAGES DISSIMILAR TO WHITEHALL FAUN A 

Faunas from many areas analyzed have low IFR 

values with the Whitehall fauna at the species level. 

Causes of the low degree of similarity are probably 

multiple and perhaps in large part influenced by the 

varying quality and quantity of taxonomic information and field collecting in the different areas. For 

this reason, comparisons of generic occurrences 

should be evaluated cautiously. 

Low IFR values, ranging from 0 to 37, were calculated for generic occurrences between the Whitehall fauna and the Eagle area of Alaska ; McCone 

County, Mont. ; southwestern Montana; central N evada; the Marathon region, Texas; Oaxaca, Mexico; 

the Frederick and Grove Formations of Maryland; 

Saratoga Springs, N.Y.; the Taconic sequence of 

eastern New York; the St. Albans area of Vermont; 

Levis, Quebec; and western Newfoundland (table 

4). Several Saukia Zone occurrences which have low 

IFR values with the Whitehall fauna are similar to 

one another and are characterized by the so-called 

Hungaia magnifica fauna (Rasetti, 1944, 1945, 

1963), which is thought to characterize North 

American "outer detrital belt" (basinal) sites 

(Palmer, 1969, 1972b). Such areas include the Eagle 

* 

; ;;-

;: e CD ~ ~ 'tl 

..c:l = ~ ~ ..!<: ell .a = "" ::a ~ lll .... lllO 0 

~ = ::: c:i' =-- =· ... :s ~ ~ ~ 

= ].- ]~ ~ 0 

"" ~ =s !it ..... Ql 

cG ·c = s:: Ql 

gj t- ~ t' 5:3 5~ t' z ~ :;a ~ s:: g z ::ae~~ ::a~ ~ 0 ;- ~ gj 0'> 0 :; Ql ri E ., s Ql 

~ ~ >< m· Ql e = ~ > s::"" s:: > "" "" 'tl Ql lll o:!O o:lO "' Ql 10 s:: $ E-t 00 "' s:: ·s. :c;~ .... "" !it > (.) 

"' ] =· -5c.? Ql Ql 

~ Ql gj ~ i "' ·~ :( (.) Ql z (.) ri !it "' 0 E-t s:: 0 

~& al'tl = s:: 'tl 'tl (.) 

~ 'i ~§ s:: Ql ·c Ql ~ 

"' "' ·~ "" a ..,· ~ ~ "' i 0 Po~ "" ~ A al ,..Q s:: ::;: "" Po~ $ 0' rJJ z i ::;: :a p...c:l ~ lll ·c; z s:: Ql Ql 

~ <(.) < .... ~ al s:: 0 (.) 0 ~ 

c;~ (.) "' c; "" s:: -:3 ri ~ 

~ s:: -(.) !it bel ,..Q al 

"" (.) Ql "" "'o -:3 ·a .s < s .b $ "' "' 0 ~ .!3 Ql .b§ .b~ 0 "' ., s:: 8 "" >< s:: ~ A "" (.) "" Ql "> ~ al "' "' s A ~0 ~~ 0 al "' ,.3 0 ~ "" ::;: 0 ~ < r.:1 ~ o-- o-- z E-t rJJ rJJ j:'Q 

X X X 

X X X ? 

? X 

X X X X X 

X X - X X X 

25 

0 to 0 0 63 50 13 * 37 13? 13 * 0 0 13 * 37? 

area of Alaska ; central Nevada (in part) ; the Marathon region of Texas; the Frederick and Grove Formations of Maryland; the Taconic sequence of eastern New York; the St. Albans area, Vermont; Levis, 

Quebec; and western Newfoundland. The occurrence of the Hungaia fauna seems to be related to 

basinal sedimentary environments or shelf-edge carbonates that may occur as subsequent or penecontemporaneous allochthonous debris flows into basinal environments (Kindle and Whittington, 1958, p. 

340; also see Bird and Dewey, 1970, fig. 7a). 

The low IFR value between the Trempealeauan 

fauna at Saratoga Springs and Whitehall is an enigma that cannot be satisfactorily explained at present. 

The Hoyt trilobite fauna is dissimilar to all other described faunas except for the occurrence of the 

ubiquitous Plethometopus, Plethopeltis, and "Prosaukia" (a species not closely related to the Whitehall form). The differences between the Hoyt and 

Whitehall faunas may be a result of difference in 

age, but if this is true one might expect to find the 

Hoyt fauna in the carbonate facies of Saukia subzones in the relatively well known sections in Oklahoma, Texas, and the Great Basin. However, the 

fauna has not been discovered in these areas in spite 

of a considerable amount of collecting. This suggests 
BIOFACIES DISTRIBUTION 17 

TABLE 4.-Known North American occurrences of trilobite genera recognized from the Saukia Zone at Whitehall, N. Y. 

[Simpson's (1960) index of faunal resemblance (,IFR) is a rough measure of the degree of apparent biogeographic similarity between White- hall and other areas of occurrence. Data-source numbers given in parentheses are explained in fig. 6. Explanation of symbols: X established occurrence; -, not known to occur; ?, questionable identification; *, insufficient data for computation. See text for discussion of' each area] 

Area 

Acheilops Ulrich -------------------------- Bowmania Walcott ------------------------ "Calvinella" Walcott ---------------------- Euptychaspis Ulrich ----------------------- Plethometopus Ulrich --------------------- Plethopeltis Raymond --------------------- "Prosaukia" Ulrich and Res,ser -------------

Stenochilina Ulrich -------------------------

X 

X 

X 

X X 

X 

X 

X 

X 

X 

X 

X 

X X X X ? 

X X X ? ? 

X X X X ? 

X X X X X 

X XX X X X X 

X X X X X 

X X X X X 

-X X ? 

... 

1: 

·c; 

~ 

s 

0 

0 

'"' j:Q 

X X X X 

X ? X 

X X 

13 37 25 

Index of faunal resemblance (IFR) --------- 0 50 13 0 0 87 0 0 87 87 75 75 63 to to 0 37 to 13 25 

that the Hoyt fauna probably reflects environmental 

conditions different from those reflected by the 

Whitehall fauna. 

Halley (1971a) noted that although the Hoyt and 

parts of the Whitehall Formations contain similar 

depositional textures, the Hoyt differs in possessing 

a high content of carbonaceous residue and dolomite and lacks chert and length-slow chalcedony. 

Also, the Hoyt fauna contains representative elements of a greater number of phyla than does the 

Whitehall. Walcott (1912b) reported gastropods, 

trilobites, and inarticulate brachiopods from the 

Hoyt, and Halley (1971a) found echinoderm and 

dasycladacean algal fragments. (See pl. 4, figs. 7, 

8.) Inarticulate brachiopods, dasycladacean algae, 

and echinoderm plates were searched for but not 

identified from the Whitehall limestones. The absence of echinoderms from the Whitehall samples 

and the absence of length-slow chalcedony from the 

Hoyt suggest that the Hoyt fauna may have lived in 

a more normal saline environment than the Whitehall fauna. Although no quantitative estimate of the 

salinity fluctuations of the two areas can presently 

be made, it is reasonable to infer that either the 

magnitude or the periodicity of salinity fluctuations 

25? 87? 37? 

was less in the Hoyt depositional environment than 

in that of the Whitehall Formation. Such environmental differences could account for faunal dissimilarity between the two areas. However, further 

study in the Saratoga Springs area is needed to 

clarify the causes of faunal dissimilarity between 

the Hoyt, Whitehall, and other carbonate belt sites 

in North America. 

The McCone County area of Montana (Lochman, 

1964a) has only one genus reported in common with 

the Whitehall area. The site is characterized by 

intercalated terrigenous shale and limestone-pebble 

conglomerate (Lochman and Wilson, 1967), suggesting, together with the faunal evidence, that the 

area was part of an inner shelf facies. 

Grant (1965, p. 88) reported Trempealeauan fossils from part of the Snowy Range Formation in 

southeastern Montana and adjacent Wyoming, 

which he assigned to the Illaenurus Zori"e. The zone 

contains no species or genera in common with the 

Whitehall assemblages. However, the Illaenurus 

Zone is probably early Trempealeauan in age 

(Grant, 1965; Longacre, 1970) so that differences 

between it and Whitehall could be due to temporal 

rather than environmental factors. 
18 LATE CAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

Faunas described from Oaxaca, Mexico, differ 

markedly from both the Hungaia magnifica biofacies 

and the inner shelf biofacies which also shows low 

IFR values. The Oaxaca fauna may be classified as 

basinal facies, but it is most similar to described 

faunas from Argentina and the Tremadocian facies 

of eastern Canada, Great Britain, and Scandinavia 

(Robison and Pantoja-Alor, 1968, p. 772) rather 

than the North American basinal H ungaia magnifica 

biofacies. 

The methods used here for measuring faunal resemblance do not allow quantitative conclusions 

concerning the homogeneity or heterogeneity of the 

Saukia Zone biofacies belts. Estimates of homogeneity or heterogeneity rely on subjective evaluation of 

faunal lists, published formal taxonomic studies, and 

museum collections. 

On the basis of the published and newly described 

faunal evidence, however, (Taylor, and other 1971, 

unpub. data), the Upper Cambrian carbonate-shelf 

facies seems to have a relatively homogeneous trilobite fauna. In contrast, North American basinal 

facies sites seem to be occupied by at least two 

faunas, the Hungaia magnifica biofacies and the 

Tremadocian faunas described from Mexico (Robison and Pantoja-Alor, 1968), and perhaps a third 

-the Hedinaspis fauna-in Alaska (Palmer, 1968) 

and the central Great Basin (Taylor, 1971, and 

other unpub. data). 

Rowell and McBride (1972a, c), Rowell, McBride, 

and Palmer (1973) recently made a quantitative 

study of Trempealeauan trilobite distribution in 

North America using multivariate-analysis techniques applied to nearly all the available trilobite 

data. Some results of their study were the recognition of a "North American faunal province" that 

is divisible into two "subprovinces," a restricted 

shelf subprovince (inner-shelf detrital and outershelf carbonate facies of this report) and a shelf 

margin-open ocean subprovince (basinal facies of 

this report) . The analysis by Rowell, McBride, and 

Palmer (1973) supports earlier suggestions (Rowell 

and McBride, 1972b) that faunas of the marginal 

shelf-open ocean (Tremadocian of Mexico and 

H edinaspis basinal biofacies of this report) are 

geographically heterogeneous and have affinities 

with either Asia or Europe. 

Many terminological differences exist between the 

report by Rowell, McBride, and Palmer ( 1973) 

and this one. However, an important conclusion to 

be made at this time is the general agreement that 

for the North American Trempealeauan, the greatest faunal change occurs between the outer-shelf 

carbonate biofacies and the offshelf basinal biofacies. 

Further understanding of possible causes of observed patterns of trilobite distribution will probably result from greatly needed detailed sedimentological studies of the rocks enclosing the various 

faunas and from taxonomic studies of trilobites 

from those areas for which available data are insufficient or obsolete. 

SYSTEMATIC PALEONTOLOGY 

INTRODUCTORY STATEMENT 

Trilobite morphological terminology used in the 

systematic descriptions follows the "Treatise on 

Invertebrate Paleontology, Part 0" (Harrington 

and others, 1959) except that nomenclature for 

glabellar furrows and lobes follows Henningsmoen 

(1957, p. 13) : lateral glabellar furrows are numbered forward from the posterior end, beginning 

with SO (occipital furrow) and proceeding S1, S2, 

S3, and S4 ; lateral glabellar lobes are also numbered 

forward from the posterior end beginning with LO 

(occipital lobe), and proceeding L1, L2, L3, and L4. 

Henningsmoen's system is preferred here over the 

Treatise system because it usually results in an 

economy of words without loss of precision in telegraphic descriptions, and it lacks the ambiguity of 

the 1p, 2p, and so forth, system advocated in the 

Treatise by providing separate notation for lobes 

and furrows. 

Economy of words in systematic descriptions is 

also made possible by the use of several other terms 

in Henningsmoen's system (1957, p. 12-14). These 

terms, together with the Treatise equivalent in parentheses, are as follows : Preocular suture (anterior 

section of facial suture), postocular suture (posterior section of facial suture) , anterior fixigena (anterior area of fixigena), interocular fixigena (palpebral area of fixigena), posterior fixigena (posterior 

area of fixigena), and ocular incisure (no Treatise 

term). 

The terms "corner angle," "inner spine angle," 

and "outer spine angle" (Henningsmoen, 1957) are 

simple and useful for describing angles in the genal 

corner region of librigenae. The term "eye socle" is 

used, following Shaw and Ormiston (1964), in preference to "eye platform." 

Gill (1949, p. 572) proposed that the term "prosopon" be used in place of "ornament" in the description of surface appearance of fossil specimens to 

deemphasize the nonfunctional connotation of the 

term ornament. (Also see Wright, 1950; Gill, 1951.) 
SYSTEMATIC PALEONTOLOGY 19 

The surface appearance of trilobites is highly variable. Some forms have surface sculpture consisting 

of anastomosing ridges, bertillion pattern, and other 

features of uncertain functional significance, whereas others have various kinds of perforate tubercles 

or surface pits that probably were functionally 

related to sensory setae in the living animal. An 

added difficulty arises in description of the surface 

appearance of molds and casts. For example, features visible on internal molds of exoskeletal parts 

are a negative replica of the inner, or visceral, surface of the exoskeleton. "Ornament" seems particularly incongruous in the description of such features. 

Therefore, Gill's usage of prosopon has been adopted 

here as a descriptive term for the surface appearance of fossils. In trilobite descriptions, this usage 

is applicable to inner and outer actual surfaces, internal and external molds, and internal and external 

casts of exoskeleton parts. 

Class TRILOBITA Walch, 1771 

Family CA TILLICEPHALIDAE Raymond, 1938 

Genus ACHEILOPS Ulrich, 1931 

Ackeilops Ulrich in Bridge, 1931, p. 218; Kobayashi, 1942, 

p. 17 4; Rasetti, 1954, p. 611; Winston and Nicholls, 

1967, p. 77. 

Type species.-Acheilops dilatus Ulrich in Bridge, 

1931, by original designation. 

Diagnosis.-Catillicephalid trilobites with palpebral lobes that range in length from approximately 

0.3 to 0.4 of cranidial length (exsagittal (exsag.)) 

and center posterior to the cranidial midpoint opposite Sl. Posterior fixigenae are subparallel sided. 

Frontal area and anterior fixigenae are absent. 

Discussion.-Winston and Nicholls (1967, p. 77) 

discussed the characteristics of Acheilops and gave 

reasons for its inclusion in the Catillicephalidae. 

Their classification is followed here. 

There are apparently three nominal species of 

Acheilops: Acheilops dilatus, the type species from 

near Eminence, Mo. ; Acheilops masonensis Winston 

and Nicholls, 1967, from the Wilberns Formation 

of central Texas; and Acheilops norwalkensis Ulrich and Resser, 1930, from Monroe County, Wis. 

Acheilops norwalkensis was illustrated (Ulrich and 

Resser, 1930, pl. 21, fig. 8) but apparently never 

described. However, the name is available under the 

rules of the International Code on Zoological Nomenclature (1964), Article 12, by indication. The slab 

illustrated by Ulrich and Resser contains two cranidia attributable to Acheilops. Both have axial 

glabellar furrows, which diverge in the region of the 

interocular fixigena and have faint but complete 

palpebral furrows and lunate palpebral lobes which 

are centered posterior to the glabellar midpoint and 

opposite the S1 furrows. 

The type collection of A. dilatus could not be 

located in the USNM collections, nor could any other 

specimens be located among material from the type 

locality (102j, old series). This constitutes a dilemma as A. dilatus is the type species of the genus. The 

problem is compounded by the fact that the original 

material was collected from residual cherts near 

Eminence, Mo. Thus, topotype material cannot be 

objectively recollected. Fortunately, the concept of 

Acheilops seems sufficiently well characterized on 

the basis of Ulrich's original description and Winston and Nicholls' description of A. masonensis; 

designation of a neotype does not seem necessary at 

present. 

Acheilops norwalkensis is similar to A. dilatus as 

illustrated and described by Ulrich ( 1930, p. 219, 

pl. 19, figs. 21, 22). Two differences can be noted in 

comparison with Ulrich's description of A. dilatus. 

He described the palpebral regions of A. dilatus as 

being ''apparently always without furrows (s) .'' 

However, as pointed out by Winston and Nicholls 

(1967, p. 77), the furrows are shown in Ulrich's 

illustrations (1930, pl. 19, figs. 20-22) of the types. 

In Ulrich's (1930, p. 219) original discussion of 

A. dilatus, he referred to a form, not mentioned by 

name, from Monroe County, Wis., which differs 

from A. dilatus in having a "greater longitudinal 

convexity of the anterior half of the glabella." This 

probably refers to A. norwalkensis and seems to be 

the only morphological difference between it and A. 

dilatus that can be detected from the information 

and material currently available. 

Acheilops masonensis Winston and Nicholls 

Plate 1, figures 4, 5 

Acheilops masonensis Winston and Nicholls 1967, p. 77, pl. 

11, figs. 23-25; Longacre, 1970, p. 15, pl. 6, fig. 19; 

Stitt, 1971, p. 15, pl. 7, fig. 5. 

Material available.-One cranidium and one librigena from locality 470b and one cranidium from 

locality H-3. 

Description of Whitehall material.-Cranidium 

subtrapezoidal in outline, strongly convex sagittally. 

Glabella expanded anteriorly, basal width 0.8 length. 

Axial glabellar furrows deeply impressed. Two pairs 

lateral glabellar furrows. S1 shallow, geniculate. S2 

shallow, nearly transverse, not connected across 
20 LATE CAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

midline. Occipital ring simple, slightly convex, posterior edge rounded, medial region not preserved. 

Occipital furrow deep. Frontal area not differentiated from glabella. Anterior border and border furrow absent. Anterior fixigena. absent. Interocular 

fixigena lunate, poorly differentiated from palpebral 

lobes. Postocular fixigena subparallel sided, length 

(transverse (tr.)) 0.8 occipital lobe length (tr.). 

Palpebral lobes large, nearly flat, lunate, length 

(exsag.) 0.3 cranidial length, centered opposite Sl. 

Palpebral furrow faintly developed on posterior onethird of palpebral region. Preocular facial sutures 

strongly divergent, coursing coincident with anterior parts of axial glabellar furrows. Postocular facial 

sutures transverse, nearly straight. 

Librigena length approximately four times width, 

nearly vertical in life position. Genal field not differentiated from border. Eye socle with attached holochroal visual surface. Genal spine short, bluntly 

pointed. 

Prosopon consists of closely spaced coarse granules on the .external surface except in furrows and 

branching ridges on the anterior lobe of the glabella 

and librigena. 

Discussion.-A cheilops mason en sis has been reported from the Saukiella serotina and Corbinia 

apopsis Subzones in the Wilberns Formation of central Texas (Winston and Nicholls, 1967; Longacre, 

1970). In the original description, Winston and 

Nicholls (1967) noted that some specimens attributed to A. masonensis have shallow lateral glabellar furrows, whereas others possess rather deeply 

impressed furrows. The Whitehall specimens are 

most similar to the shallow-furrowed Texas forms 

(see Longacre, 1970, pl. 6, fig. 19) except tha.t they 

are more coarsely granular and the palpebral furrows are present only on the posterior part of the 

palpebral region. 

Stitt (1971) reported A. masonensis from the 

Saukiella junia and Saukiella serotina Subzones in 

the Signal Mountain Formation of south-central 

Oklahoma. The New York form differs from the 

specimen illustrated by Stitt (1971, pl. 7, fig. 5) in 

having shallower lateral glabellar furrows. Stitt 

noted that some forms hig4 in the range of A. masonensis in Oklahoma possess coarser granules than 

earlier forms. This phenomenon is similar to that 

shown by the New York specimen. 

The New York material differs from A. norwalkensis (on USNM 72700) from Monroe County, 

Wis., in having an incomplete rather than complete 

palpebral furrow, relatively shorter (exsag.) palpebral lobe ( exsag. length/cranidial length 0.3 rather 

than 0.4), and axial glabellar furrows that are subparallel rather than divergent in the interocular fixigenal region. 

Occurrence.-Saukiella serotina Subzone, localities H-3 and 470b, Washi~gton County, N.Y. 

Genus STENOCHILINA Ulrich, 1931 

Stenochilina Ulrich in Bridge, 1931, p. 215. Rasetti, 1954, 

p. 606; Rasetti, in Harrington and others, 1959, p. 

0285. 

Type species.-Stenochilina spinifera Ulrich in 

Bridge, 1931, by original designation. 

Diagnosis.-Glabella subparallel sided, rounded to 

bluntly rounded anteriorly; frontal area narrow, 

lacking anterior border; palpebral lobes anterior to 

glabellar midpoint, centered opposite L2 lobe, below 

level of interocular fixigena; occipital spine present 

or absent; prosopon coarsely granular. 

Discussion.-Rasetti's (1954, 1959) diagnosis of 

Stenochilina is slightly modified to accommodate features observed in Stenochilina sp. A from New York. 

The principal change is to include forms that lack 

an occipital spine. 

Rasetti (1954, p. 606) restricted Stenochilina to 

S. spinifera, the type species from the Trempealeauan near Eminence, Mo. Stenochilina spinifera has 

also been reported from the Conococheague Formation in Washington County, Md. (Rasetti, 1959, p. 

383). 

Stenochilina is most similar to Triarthropsis from 

which it differs in the presence of larger, welldefined, anteriorly located palpebral lobes and coarse 

granular prosopon. 

Stenocbilina sp. A 

Plate ·1, figures 6-10 

Material available.-Eight cranidia from locality 

418e (old series). 

Description.-Cranidium subtrapezoidal in outline, moderately convex. Glabella subparallel sided, 

nearly straight sided, basal width about 0.9 length, 

anteriorly truncate. Axial glabellar furrow deep; 

preglabellar furrow deep, slightly depressed at midline. Two pairs lateral glabellar furrows, deeply impressed. S1 bifurcate, posterior segment geniculate, 

faintly connected to SO in large specimens; anterior 

segment connected across midline. S2 deeply impressed, connected across midline. S3 · absent. S4 

present or absent; if present, short, oblique backwards, straight. Occipital ring composite, lacks 

medial spine or node. Occipital furrow deeply impressed. Frontal area sagittally convex, length about 
SYSTEMATIC PALEONTOLOGY 21 

0.1 cranidiallength, anterior border absent. Anterior fixigena slope anterolaterally about 45° from 

horizontal. Interocular fixigena width 0.3 adjacent 

glabellar width. Posterior fixigena subparallel sided, 

bent posteriorly, about 0.8 occipital lobe width (tr.). 

Eye ridge absent. Palpebral lobe length (exsag.) 

approximately 0.5 glabellar length, lunate, flat, below level of interocular fixigena, centered anterior 

to glabellar midpoint opposite L2. Preocular facial 

sutures divergent then converging evenly to sagittal 

line forming rounded anterolateral corners of anterior fixigena. Postocular facial sutures strongly 

divergent, slightly convex, forming nearly transverse character-state. 

Librigena, thorax, and pygidium unknown. 

Prosopon consists of evenly spaced coarse perforate ( ?) granules and closely spaced fine granules 

in furrows and interspersed between coarse 

granules. 

Discussion.-Stenochilina sp. A differs from the 

holotype of S. spinifera in the absence of an occipital 

spine, in having a relatively shorter frontal area 

(length/cranidiallength 0.10 rather than 0.07 in the 

holotype), a more straight-sided glabella, and in 

the presence of diminutive S4 furrows on some 

individuals. 

Material from the Conococheague Limestone of 

Maryland was assigned to S. spinifera by Rasetti 

(1959, p. 383, pl. 52, figs. 15, 16). The specimens are 

similar to the New York material in having nearly straight-sided glabellae and diminutive S4 furrows (shown in Rasetti's fig. 15). The only significant difference between the New York and Maryland 

forms seems to be the presence of an occipital spine 

in the latter. 

The New York material is placed in open nomenclature because of uncertainty as to the precise location of the original collecting site and because the 

available specimens are few and rather poorly 

preserved. 

Occurrence.-Saukia Zone, locality 418e, Washington County, N.Y. 

Family HETEROCARYONIDAE Hupe, 1953, emended Clark and Shaw, 1968 

Genus BOWMANIA Walcott. 1925 

Bowmania Walcott, 1925, p. 73; Rasetti, in Harrington and 

others, 1959, p. 0517. 

Type species.-Arethusina americana Walcott, 

1884, by original designation. 

Diagnosis.-The concept of Bowmania described 

by Rasetti (in Harrington and others, 1959) is followed here. 

527-763 0- 74- 4 

Bowmania d. B. pennsylvanica Rasetti 

Plate 2, figures 12-14 

Bowmania pennsylvanica Rasetti, 1959, p. 395, pl. 55, figs. 

1-5, text fig. 1; Longacre, 1970, p. 56, pl. 6, figs. 4, 

5; Stitt, 1971, p. 21, pL 7, fig. 10. 

Material available.-One cranidium from locality 

H-1. 

Description of Whitehall material.-Cranidium 

subrectangular in outline, strongly convex sagittally. 

Glabella parallel sided, strongly convex sagittally 

and transversely, basal width 0.85 length, length 0.7 

cranidial length (excluding occipital ring). Axial 

glabellar furrows deep, anterior glabellar furrow 

less deep, convex anteriorly. Two pairs lateral glabellar furrows. S1 deep, straight, short, oblique 

backwards. S2 deep, pitlike. Occipital ring simple, 

straight. Occipital furrow deep, straight, bent forward laterally. Frontal area convex, strongly downsloping, length (sagittal (sag.)) 0.3 cranidial 

length. Anterior border convex, length (sag.) 0.4 

preglabellar field length, well defined by deep anterior border furrow. Anterior fixigena downsloping to 

near vertical anterolaterally. Interocular fixigena 

upsloping from axial glabellar furrow. Posterior 

fixigena not preserved. Eye ridge well developed, 

curved slightly backward toward palpebral lobe, 

abutts glabella anterior to S2. Palpebral lobes poorly preserved, slightly raised, centered opposite 

S2 ( ?) . Preocular facial sutures strongly divergent, 

directed downward anterolaterally to near vertical. 

Postocular facial sutures not preserved. 

Prosopon consists of scattered coarse perforate 

granules on the raised parts of the glabella, fixigenae, anterior border, and occipital lobe; closely 

spaced fine granules on the raised parts of the glabella, fixigenae, anterior border, and occipital lobe; 

and closely spaced fine pits on the anterior fixigenae 

and preglabellar field. 

Discussion.-Rasetti ( 1959) originally described 

Bowmania pennsylvanica from cranidia collected at 

the type locality ("cca") in the Conococheague Limestone, Franklin County, Pa. He also tentatively assigned some forms to the taxon from near Frederick, 

Md. Rasetti designated a holotype and two paratype 

cranidia for B. pennsylvanica. Examination of the 

types shows that the preglabellar-field prosopon of 

the paratypes differs from that of the holotype. The 

holotype cranidium (Rasetti, 1959, pl. 55, figs. 1-3) 

is 4.6 mm long (sag.) and has evenly spaced scattered coarse granules and interspersed closely spaced 

fine granules on the preglabellar field. Paratype 
22 LATE CAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

cranidia (Rasetti, 1959, pl. 55, figs. 4, 5) are 3.9 

and 2.9 mm long (sag.). Prosopon of the preglabellar fields of the two paratypes is similar to that of 

the holotype except for the presence of abundant 

pits interspersed among the fine granules. The 

cranidium from the Whitehall Formation is 3.5 mm 

long (sag.) and intermediate in size between the 

two paratypes, and prosopon is similar to both paratypes. Therefore, the Whitehall cranidium is here 

considered conspecific with the paratypes. However, 

whether these forms are conspecific with the bolotype cannot be proved without additional data. The 

fact that the nonpitted holotype is larger than the 

pitted forms suggests that late ontogenetic morphological changes may be a factor in explaining the 

differences. However, the available sample is too 

small to rule out the alternative possibility that two 

species are present in the type collection. The Whitehall cranidium is only tentatively assigned to Bowmania pennsylvanica for this reason. 

Bowmania pennsylvanica was reported by Longacre (1970) from the Sa.ukiella serotina Subzone in 

the Wilberns Formation of central Texas. The Texas 

forms differ in possessing glabellae that are slightly 

expanded anteriorly. However, presence or absence 

of pits on the anterior part of the cranidium was not 

mentioned by Longacre. 

Stitt (1971) reported B. pennsylvanica from the 

lower part of the Signal Mountain Formation in 

south-central Oklahoma. The taxon ranges through 

the Saukia Zone in that area (Stitt, 1971, p. 22). 

Stitt also noted that some specimens have "pits scattered around the granules" but the feature was not 

discussed in detail. 

Occurrence.-Saukiella serotina Subzone at locality H-1, lower Whitehall Formation, Washington 

County, N.Y. 

Family MISSISQUOIIDAE Hupe, 1953 

Genus MISSISQUOIA Shaw, 1951 

Missisquoia Shaw, 1951, p. 108; Winston and Nicholls, 1967, 

p. 88. 

Type species.-Missisquoia typicalis Shaw, 1951, 

by original designation. 

Diagnosis.-The diagnosis provided by Winston 

and Nicholls (1967) is followed here. 

Discussion-Missisquoia is a widespread genus in 

North America. The taxon is known from the Missisquoia Zone of Vermont (Shaw, 1951), New York 

(this report), Oklahoma (Stitt, 1971), Texas (Winston and Nicholls, 1967), Utah and Nevada (Taylor, 

1971), Wyoming (U.S. Geol. Survey, unpub. data, 

1953), and Alberta (Derby and others, 1972). 

Genera closely similar to M issisquoia are unknown 

in North America. However, Parakoldinioidia Resser and Endo (Endo and Resser, 1937, p. 329, pl. 71, 

figs. 17-23), based on P. typicalis Resser and Endo 

from the Upper Cambrian of Manchuria, has some 

similarities. Both forms possess a more or less parallel sided to slightly expanding glabella with short 

lateral glabellar furrows and a distinct anterior 

glabellar notch. The similarity seems to be greatest 

between Missisquoia depressa Stitt (1971, pl. 8, fig. 

5, 6) and Parakoldinioidia typica,lis (see Kobayashi, 

1956, pl. 2, fig. 10-13). Both have bifid S1 lateral 

glabellar furrows. Also, the small size of the exoskeleton and position of the palpebral lobes is similar 

in both species. The principal differences between the 

two forms are the strongly convergent preocular 

facial suture across the anterior border in Parakoldinioidia and the parallel preocular sutures in 

Missisquoia. Whether the similarities represent close 

relationship or homeomorphy is unknown at present. 

Missisquoia typicalis Shaw 

Plate 3, figures 1-9 

Missisquoia typicalis Shaw, 1951, p. 108, 109, pl. 23, figs. 

1-10; Winston and Nicholls, 1967, p. 88, 89, pl. 13, 

figs. 2?, 5, 6, 10, 12, 15, 181; Stitt, 1971, p·. 26, pl. 8, 

figs. 1-4. 

Material available.-Thirty cranidia, four librigenae, and 52 pygidia from locality 4 70bl ; 45 cranidia, six librigenae, and 47 pygidia from locality 

7098-CO; 59 cranidia, 25 librigenae, and 123 pygidia 

from locality 7099-CO; and, two cranidia and one 

pygidium all questionably assigned from locality 

H-2. 

Description of Whitehall material.-Exoskeleton 

oval in outline, moderately convex, probably about 

one-half em long. Cranidium subquadrate, moderately convex. Glabella variable, slightly tapered to 

slightly expanded anteriorly, basal width 0. 7 to 0.8 

length (sag.), anterior lobe with medial notch. Axial 

glabellar furrows well defined, anteriorly confluent 

with anterior border furrow. Lateral glabellar furrows pitlike on sides of glabella. S1 convex, deeply 

impressed, connected to axial glabellar furrow. S2 

transverse, straight, deeply impressed, connected to 

axial glabellar furrow. S3 transverse, straight, 

faintly impressed, not connected to axial glabellar 

furrow. S4 faint or absent, straight, connected to 

axial glabellar furrow. Occipital ring simple, rounded posteriorly. Occipital furrow deep, straight. 

Medial region of occipital ring with node or short 
SYSTEMATIC PALEONTOLOGY 23 

spine in small individuals, node may or may not be 

present in large individuals. Preglabellar field absent. Anterior border horizontal, flat, length (sag.) 

about 0.1 cranidial length. Anterior margin evenly 

rounded. Anterior fixigena evenly downsloping anterolaterally. lnterocular fixigena (including palpebral lobe) convex, raised about one-half glabellar 

height, width (tr.) about 0.5 adjacent glabellar 

width. Posterior fixigena subtriangular, downsloping laterally, about equal in width (tr.) to occipital 

ring. Posterior border furrow not connected to occipital furrow. Eye ridge faintly developed to absent, 

abuts axial glabellar furrow opposite S3 where 

observable. Palpebral lobe rounded, subhorizontal, 

not differentiated from interocular fixigena by palpebral furrow, length (exsag.) 0.3 to 0.4 glabellar 

length (sag.), centered opposite S2. Preocular facial 

sutures parallel, straight, downsloping anteriorly at 

about 30° angle from horizontal. Postocular facial 

sutures divergent, convex. 

Librigena narrow, evenly rounded laterally. Genal 

field convex, downsloping laterally to deep border 

furrow, genal field continuous with genal spine posterolaterally through genal corner. Ocular incisure 

with raised eye socle and holochroal visual surface 

often attached. Eye socle about 0.5 height of visual 

surface. Lateral border horizontal, flat, differentiated from genal field by abrupt change in slope. 

Genal spine broken on all observed specimens. 

Thorax unknown. 

Pygidium variable, strongly convex to moderately 

convex, subtriangular in outline, length about 0.8 

width. Axis straight sided, tapered posteriorly, nine 

axial rings plus terminal piece. Axial rings become 

faintly defined posteriorly. Pleural regions flat, 

strongly downsloping to near vertical at margin, 

five pairs deeply impressed interpleural furrows, six 

pairs les.s deeply impressed pleural furrows. Pleurae 

terminate distally into apparent blunt spines. 

Prosopon consists of fine closely spaced granules 

on the glabella, fixigena, genal field, and pygidium 

and occasional scattered larger granules. The borders of the cranidium and librigena have longitudinal terrace lines. 

Discussion.-Samples from the Whitehall Formation are morphologically variable in degree of taper 

of glabella, convexity of pygidium, and relative 

abundance of large scattered granules on dorsal 

surfaces. 

The type material from the Highgate Formation 

near Highgate Falls, Vt. (Shaw, 1951, 1955, 1958), 

has similar variability, although some diastrophic 

distortion seems to have modified the Vermont material. Comparison of New York specimens with 

undistorted topotypic collections from the Highgate 

suggests that the forms are conspecific. 

Winston and Nicholls (1967) assigned material 

from the Wilberns Formation of central Texas to M. 

typicalis. The Texas material is similar to the New 

York specimens except for the attributed librigena 

(Winston and Nicholls, 1967, pl. 13, fig. 2). The 

Texas librigena is equidimensional, with a short 

( tr.) posterior margin, and slender in curved genal 

spine. Such shape contrasts markedly with librigenae here attributed to M. typicalis from New 

York. The New York form is rather long and slender 

and lacks a posterior border furrow. The otherwise 

strong similarity between cranidia and pygidia from 

Texas and New York suggest that the librigena 

illustrated by Winston and Nicholls may have been 

attributed in error and should be reevaluated. 

Stitt (1971) attributed material from the upper 

part of the Signal Mountain Limestone of southcentral Oklahoma toM. typicalis. The specimens illustrated by Stitt seem to fall within the range of 

variation of the New York material. 

Missisquoia typicalis occurs in the upper part of 

the Notch Peak Limestone of west-central Utah 

(Taylor, 1971). The Utah collections contain a 

greater proportion of individuals with slightly expanded glabella than do the New York collections. 

However, taxonomic significance of this difference 

is presently unknown as both collections are highly 

variable in this feature. 

Occurrence.-Missisquoia Zone localities 470ht, 

7098-CO, 7099-CO, and H-2 ( ?) from the upper 

Whitehall Formation, Washington County, N.Y. 

Family PLETHOPEL TIDAE Raymond, 1925 

Genus PLETHOMETOPUS Ulrich, 1931 

Plethometopus Ulrich in Bridge, 1931, p. 221 

Type species.-Bathyurus armatus Billings, 1860, 

by original designation. 

Discussion.-Morphological characteristics of the 

genus have been summarized in Harrington and others (1959, p. 0410). Plethometopus is distinguished 

from other members of the Plethopeltidae by the 

presence of at least four of the following five features: a triangular-shaped occipital region, occipital 

furrow, effaced preglabellar furrow, faint to absent 

posterior axial glabellar furrows, and posterior border furrows. 
24 LATE GAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

Pletbometopus obtusus Rasetti 

Plate 1, figures 11-14 

Plethometopus obtusus Rasetti, 1945, p. 472, pl. 62, figs. 1, 

2; Rasetti, 19·59, p. 383 pl. 53, figs. 11-14; Longacre, 

1970, p. 19, pl. 6, figs.. 14, 15; S.tittt, 1971, p. 35; pl. 

6, fig. 16. 

Unassigned pygidium no. 7, Rasetti, 1945, p. 477, pl. 62, 

figs. 29 30. 

Plethometopus modestus Ulrich. Winston and Nicholls, 1967, 

p. 87, pl. 10, fig. 11. 

Material available.-Eight fragmentary cranidia 

from locality 473f. 

Diagnosis.-A species of Plethometopus with palpebral lobes centered anterior to the cranidial midline; axial glabellar furrows only present opposite 

and posterior to the palpebral areas; slightly divergent preocular facial sutures ; subtriangularshaped occipital lobe that lacks an occipital spine; 

and a deeply impressed, posteriorly concave occipital 

furrow. 

Description of Whitehall material.-Cranidium 

subrectangular in outline, width (tr. between palpebral lobes) approximately 0.8 length (sag.), sagittally convex. Glabella undifferentiated except occipital region. Axial glabellar furrows consist of 

shallow depressions extending from posterior border 

to a position opposite palpebral lobes. Axial furrows 

absent anteriorly. Lateral glabellar furrows absent. 

Occipital ring simple, subtriangular in outline, well 

defined by occipital furrow. Occipital furrow deep, 

slightly concave posteriorly. Frontal area evenly 

downsloping at about 45° angle from horizontal, 

continuous with glabellar region. Anterior border 

absent. Posterior fixigena short (tr.), width (tr.) 

about 0.3 basal glabellar width, triangular shaped, 

deep border furrow present. Anterior fixigena undifferentiated. Palpebral lobes consist of narrow 

(tr.) raised ridges, length (exsag.) 0.2 cranidial 

length (excluding occipital lobe), centered slightly 

anterior to cranidial midpoint. Preocular facial 

sutures slightly divergent, downsloping. Postocular 

facial sutures strongly divergent, convex. 

Exoskeletal surfaces and internal molds are 

smooth. Librigena, thorax, and pygidium are unknown in Whitehall collections. 

Discussion.-Plethometopus obtusus was originally described by Rasetti (1945) from Boulder 57 at 

Levis, Quebec. Later, Rasetti (1959) recorded the 

species from the Conococheague Limestone of Washington County, Md., and attributed pygidia from 

Levis that had previously (Rasetti, 1945) been illustrated but unassigned. 

Lochman (1946, p. 551, pl. 1, figs. 7-9) described 

and illustrated Plethometopus knopfi from weathered 

dolomite 1~ miles south of Pine Plains, Dutchess 

County, N.Y. The holotype illustrated by Lochman 

(fig. 9) is similar to material from Whitehall except 

that the cranidium is more quadrate in outline. The 

ratio of cranidial width (measured transversely between distal margins of palpebral lobes) to cranidial 

length is approximately 1.0 in P. knopfi and 0.8 in 

Whitehall material attributed to P. obtusus. 

Longacre (1970) established the presence of P. 

obtusus in the Wilberns Formation of central Texas 

where she assigned occurrences of the species to the 

Saukiella serotina and Corbinia apopsis Subzones. 

The Wilberns material previously assigned to Plethometopus modestus Ulrich by Winston and 

Nicholls (1967) was reassigned to P. obtusus by 

Longacre (1970). 

Stitt (1971) collected P. obtusus from the Signal 

Mountain Formation of south-central Oklahoma 

where he assigned its occurrences to the Saukiella 

serotina and Corbinia apopsis Subzones. 

Search of the USNM collections yielded a single 

cranidium from New Jersey which can be tentatively assigned to P. obtusus. The locality is listed as 

number 11c, which Walcott (1912a, p. 178) described 

as follows: "Upper Cambrian: Hardyston quartzite 

***,O'Donnell and McManniman's quarry, Newton, 

Sussex County, N.J." Later, Walcott (1914, p. 389) 

emended the stratigraphic designation to "Kittatinny limestone." The specimen occurs as an internal 

mold in fine-grained dolomitic sandstone. The cranidium is well enough preserved to show the divergent 

preocular facial sutures, subtriangular-shaped occipital lobe, and incomplete axial glabellar furrows 

which are characteristic of the species. 

Occurrence.-Saukiella serotina Subzone, locality 

473f, Washington County, N.Y. 

Pletbometopus sp. A 

Plate 1, figures 15-17 

Material available.-One cranidium from locality 

473f. 

Description.-Cranidium subtrapezoidal in outline, strongly convex sagittally, length 0.9 width. 

Glabella undifferentiated. Axial glabellar furrows 

faint, only present on posterior one-fourth of cranidium. Occipital ring undifferentiated. Frontal area 

downsloping at about 60° angle from the horizontal. 

Anterior fixigena undifferentiated. Posterior fixigenae triangular, width (tr.) 0.3 basal glabellar 

width. Posterior border furrow shallow, pitlike. 
SYSTEMATIC. PALEONTOLOGY 25 

Palpebral lobes consist of raised ridges, length (exsag.) 0.2 cranidial length, centered anterior to cranidial midline ( 0.4 cranidial length). Preocular 

facial sutures strongly convergent, forming bluntly 

pointed anterior cranidial margin. Postocular facial 

sutures strongly divergent, convex. 

Exoskeletal and internal mold surfaces smooth 

except for bertillion prosopon on the posteriormost 

part of the occipital region. 

Discussion.-The single cranidium is similar to 

forms assigned to both Stenopilus and Plethometopus. The former usually have strongly convergent 

preocular facial sutures, narrow palpebral lobes, 

absence of dorsal furrows, and coalescence of the 

occipital region with the basal glabellar lobe. In 

contrast, species assigned to Plethometopus usually 

have slightly divergent to subparallel preocular 

facial sutures, narrow palpebral lobes, axial glabellar furrows in varying degrees of completeness, and 

usually a differentiated occipital region. An exception is Plethometopus convergens (Raymond) which 

possesses slightly convergent preocular facial sutures. However, Plethometopus sp. A differs from 

P. convergens in having more strongly convergent 

preocular facial sutures and palpebral lobes which 

are centered anterior, rather than posterior, to the 

cranidial midline. (See also Rasetti, 1959, pl. 53, figs. 

15, 16; Longacre, 1970, p. 19.) 

Morphologically, the cranidium of Plethometopus 

sp. A is intermediate between Plethometopus and 

Stenopilus. However, the subtle differences point up 

the arbitrary and highly subjective distinction between these genera when only their cranidia are 

considered. This situation should serve as a cautioning influence in applying too much emphasis on biostratigraphic correlations when only fragmentary 

smooth trilobites are available. 

Occurrence.-Plethometopus sp. A by association 

is assigned to the Saukiella serotina Subzone, at 

locality 473f, Washington County, N.Y. 

Genus PLETHOPEL TIS Raymond, 1913 

Plethopeltis Raymond, 1913, p. 64; Field, 1915, p. 37; Ulrich 

in Bridge, 1931 p. 219; Bridge and Cloud, 1947, p. 556; 

Longacre, 1970, p. 19. 

Type species.-Agraulos saratogensis Walcott, 

1890, by original designation. 

Discussion.-Plethopeltis was originally based on 

material from the Hoyt quarry (Walcott's locality 

76), 4 miles west of Saratoga Springs, N.Y. Longacre (1970, p. 19-21) recently discussed the complex 

nomenclatural history of the genus and the type collection upon which it was based. She provided a 

diagnosis and concluded that Plethopeltis can be distinguished from other genera of the Plethopeltidae 

by the presence of complete axial and preglabellar 

furrows and lack of an anterior border furrow. 

These features distinguish Plethopeltis from the 

similar genus Plethometopus Ulrich. 

Pletbopeltis sp. indet. 

Plate 1, figures 1-3 

Discussion.-Locality H-3 from the Whitehall 

Formation contains five poorly preserved cranidia 

which conform to the concept of Plethopeltis. The 

forms have well-defined axial furrows, shallow preglabellar furrows, and lack lateral glabellar furrows. 

Axial furrows are straight to slightly concave laterally. Occipital lobes are triangular in outline and 

well defined by a simple, slightly convex occipital 

furrow. Four of the internal cranidial molds retain 

sufficient exoskeletal material to show that prosopon 

consists of evenly spaced granules on three cranidia 

and a smooth surface on the fourth specimen. Surfaces of well-preserved internal molds are finely pitted. No pygidium is known from the sample. 

Granular prosopon has been reported on several 

forms assigned to Plethopeltis. They include: Plethopeltis granulosa Resser, 1942, from New York; 

Plethopeltis arbucklensis Stitt, 1971, from southcentral Oklahoma; and, Plethopeltis sp. of Longacre ( 1970) from central Texas. Plethopeltis granulosa was based on part of Walcott's hypodigm of 

Agraulos saratogensis from locality 76 at the Hoyt 

quarry, 4 miles west of Saratoga Springs, N.Y. It 

differs from the Whitehall material in having lateral 

glabellar furrows, more deeply impressed axial and 

anterior glabellar furrows, and more closely spaced 

granules. 

Plethopeltis arbucklensis Stitt differs from the 

Whitehall specimens in having laterally convex axial 

glabellar furrows and a more strongly tapered 

glabella. 

Plethopeltis sp. of Longacre ( 1970) from the Saukiella pyrene Subzone of central Texas seems similar 

to the Whitehall specimens. An apparent difference 

is the presence of axial glabellar furrows which are 

slightly convex laterally in the Texas material. The 

apparent similarity between New York and Texas 

specimens may be a result of the few features available for comparison. Because of this possibility and 

the fact that Plethopeltis seems to range throughout 

the Trempealeauan Stage, caution should probably 

be exercised in making biostratigraphic inferences. 
26 LATE GAM.BR.IAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

from material assigned to Plethopeltis unless all 

morphologic parts are present and taxa can be more 

precisely characterized than can be done on cranidial 

features alone. 

Occurrence.-Saukiella serotina Subzone, locality 

H-3, lower Whitehall Formation, Washington 

County, N.Y. 

Family PTYCHASPIDIDAE Raymond, 1924 

Subfamily PTYCHASPIDINAE Longacre, 1970 

Genus EUPTYCHASPIS Ulrich, 1931 

Euptychapsis Ulrich in Bridge, 1931, p. 217; Winston and 

Nicholls, 1967 p. 78; Longacre, 1970, p. 40. 

Type species.-Euptychaspis typicalis Ulrich in 

Bridge, 1931, by original designation. 

Discussion.-The generic concept given by Longacre ( 1970) is followed here. Information on the 

previously undescribed pygidium of E. typicalis is 

added under the description of new material below. 

Euptychaspis typicalis Ulrich 

Pla.te 2, figures 4-11 

Euptychaspis typicalis Ulrich in Bridge, 1931, p. 218, pl. 

19, figs. 5-7; Dake and Bridge, 1932, p. 740, pl. 12, fig. 

3; Rasetti, 1959, p. 393, pl. 52, figs. 11-13; Winston 

and Nicholls, 1967, p. 78, pl. 9, fig. 17; Longacre, 1970, 

p. 42, pl. 4, fig. 9; Stitt, 1971, p. 42, pl. 6, fig. 19. 

Material available.-Nine cranidia, nine librigenae, and three pygidia from locality H-1; 15 

cranidia and two librigena from locality H-3; and 

one cranidium tentatively assigned from locality 

473f. 

Description of Whitehall material.-Cephalon 

semicircular in outline, strongly convex. Glabella 

subparallel sided to expanded forward, basal width 

0.85 length. Axial glabellar furrows deep, broad; 

anterior furrow shallow. Lateral glabellar furrows 

well developed, deep. S1 and S2 continuous across 

glabella forming straplike L1 and L2. S3 faintly impressed rarely on internal molds. Occipital ring 

drawnout into broad blunt spine. Occipital spine triangular in cros·s section, inclined at approximately 

45o to horizontal. Frontal area downsloping, nearly 

vertical, length (sag.) 0.1 glabellar length. Preglabellar field absent. Anterior border wirelike or 

absent. Anterior fixigenae not differentiated, continuously curved laterally from frontal area. Interocular fixigenae upsloping, width (tr.) 0.7 adjacent 

glabellar width. Posterior fixigenae approximately 

equal to occipital ring width (tr.) Eye ridge moderately developed on dorsum, strongly developed on 

internal molds, abutts axial glabellar furrow at L3. 

Palpebral lobes poorly preserved, apparently raised 

above level of fixigenae, length ( exsag.) 0.3 glabellar 

length, centered opposite L2. Palpebral furrow deep, 

arcuate, concave abaxially. Preocular facial sutures 

convergent, convex. Postocular facial sutures weakly divergent, slightly convex. 

Librigenae long, narrow, steeply downturned laterally. Genal field downsloping continuously to lateral 

margin, anteriorly confluent with frontal area, posteriorly confluent with genal spine. Ocular incisure 

with raised eye socle and attached ( ?) visual surface. 

Posterior border deeply impressed adaxially from 

genal spine. Lateral border furrow faintly impressed. Genal spine long, length about twice cranidial length, triangular in cross section, distally 

curved slightly downward below level of cranidium. 

Thorax unknown. 

Pygidium subelliptical in outline, length 0. 7 width. 

Axis tapered posteriorly, length about 0.6 pygidial 

length (sag.), two axial rings plus terminal piece. 

Pleural regions diminutive, separated from wide 

border by ridge. Border downsloping, lower than 

pleural regions. 

Prosopon consists of reticulate pattern of ridges 

on the cranidial dorsum and heavy anastomosing 

terrace lines on the frontal area and lateral parts of 

the librigenae. Internal molds finely pitted. Pygidial 

surfaces poorly preserved, border region with scattered pits which may be fortuitous. 

Discussion.-Longacre (1970, p. 42) noted that 

cranidia assigned to E. typicalis from central Texas 

possess a narrow (sag.) anterior border. A narrow 

anterior border is present on some, but not all, specimens from New York and one of Ulrich's syntypes 

(USNM 83493) from Missouri. This feature, in 

association with relatively wide fixigenae and an 

anterior glabellar lobe that does not reach the anterior margin, distinguishes E. typicalis from other 

nominal species assigned to the genus. 

The pygidium, described here for the first time, 

has a border markedly depressed below the level of 

the axis and pleural regions. This construction probably facilitated enrollment by providing a notch for 

abutment between the ventral doublure-rostral region of the cephalon and the pygidial dorsum. 

Euptychaspis typicalis is known from the Saukia 

Zone of southern Missouri (Ulrich, 1930) and Maryland (Rasetti, 1959) ; the Saukiella junia Subzone of 

central Texas (Winston and Nicholls, 1967; Longacre, 1970) ; and the Saukiella junia and Saukiella 

serotina Subzones of Oklahoma (Stitt, 1971) and 

east-central Nevada (Taylor, 1971). 

Occurrence.-Saukiella serotina Subzone, localities H-1, H-3, and tentatively 473f, lower Whitehall 

Formation, Washington County, N.Y. 
SYSTEMATIC PALEONTOLOGY 27 

Subfamily SAUKIINAE Ulrich and Resser, 1933 

Discussion.-Ulrich and Resser (1930, 1933) published two monographs on the Upper Mississippi 

Valley representatives of the Dikelocephalidae, 

which included subfamilies Dikelocephalinae and 

Osceolinae (1930) and Saukiinae (1933). General 

impracticability of Ulrich and Resser's treatment of 

the dikelocephalid genera and species led Raasch 

(1951) to a restudy of the fossil groups and establishment of many species synonomies. Raasch (1951, 

p. 139) pointed out that among several difficulties 

with the Ulrich and Resser systematics is that the 

authors based some taxa on misattributed exoskeletal parts which originated from different localities 

and in some cases different stratigraphic horizons. 

Unfortunately, Raasch's study did not include nom.-

enclatural stabilization of the type collections or 

revised diagnoses of the dikelocephalid genera. 

The taxonomic procedure followed by Ulrich and 

Resser created a critical problem in that many type 

species were based on numerous specimens in "cotype series." This results in difficulty in comparing 

new material with type collections because attributed specimens in the type collections are suspect 

at best and biologically meaningless at the worst. 

Because of the taxonomic procedures used by ffirich 

and Resser (1930, 1933), objectively based concepts 

of the dikelocephalid genera cannot be established 

at present without a comprehensive reevaluation of 

their type species. Pending such a reevaluation I 

have chosen to apply the saukiinid generic names 

reservedly, in recognition of the possibility that they 

may not represent natural groupings of species and 

that the type collections may contain nonconspecific 

attributions of exoskeletal parts. The genera that 

are affected in this study are Calvinella Walcott and 

Prosaukia Ulrich and Resser. 

Genus CALVINELLA Walcott, 1914 

Calvinella Walcott, 1914, p. 388; Ulrich and Resser, 1933, 

p. 215; Lochman, in Harrington and others, 1959, p. 

0323; Longacre, 1970, p. 45. 

Type species.-Dikelocephalus spiniger Hall, 1863, 

by original designation. 

Discussion.-Longacre (1970) has most recently 

summarized the morphological features of species 

assigned to Calvinella. She characterized the pygidium as transversely elliptical. However, Ulrich and 

Resser ( 1933, pl. 38, 39) included several forms with 

subcircular pygidia. 

Features normally used to distinguish Calvinella 

from other genera of the Saukiinae include unequally divided pygidial pleural fields, presence of an occipital spine, and granular prosopon on the cranidium. These differences are all of doubtful taxonomic 

significance because species have been included in 

Tellerina that have unequally divided pleural regions; Prosaukia includes species with occipital 

spines, and Calvinella includes forms with bertillion, 

granular, or mixtures of both kinds of prosopon on 

cranidia. Problems relating to the artificiality of 

Calvinella and other saukiinids is discussed under 

the heading "Subfamily Saukiinae." 

"Calvinella" prethoparia Longacre 

Plate 2, figures 1-3 

Calvinella prethoparia Longacre, 1970, p. 45, pl. 6, figs. 7-

12. 

Mat erial available.-Three cranidia and one librigena from locality H-1; five cranidia, and one librigena questionably assigned from locality H-3. 

Description of Whitehall material.-Cranidium 

subtrapezoidal in outline, moderately convex. Glabella subparallel sided to slightly tapered forward, 

length (excluding occipital ring) approximately 0.9 

basal glabellar width, anteriorly truncate. Axial 

glabellar furrows wide, deeply impressed. Anterior 

glabellar furrow less deeply impressed than axial 

furrows. Four pairs lateral glabellar furrows. 81 

deeply impressed laterally, faintly geniculate, becoming shallower adaxially, connected to axial furrow, connected across midline. S2 straight, oblique 

backwards, deeply impressed laterally, becoming 

faintly connected across midline, connected to axial 

furrow. S3 shallow, straight, transverse, not connected to axial furrow. S4 shallow, straight, oblique 

forward, connected to axial furrow. Occipital ring 

simple, concave forward, with occipital spine (length 

not observed). Occipital furrow concave forward, 

deeply impressed laterally, moderately impressed 

adaxially. Preglabellar field concave, consisting of a 

broadening of the anterior glabellar furrow. Anterior border width (sag.) approximately 0.2 cranidial length, convex. Anterior border furrow deep, 

well differentiated abaxially, becoming shallower 

adaxially and inosculating with anterior glabellar 

furrow. Anterior fixigena gently downsloping anterolaterally. Interocular fixigena width (tr.) 0.5 

adjacent glabellar width, raised above level of axial 

glabellar furrow, below level of glabellar crest, subhorizontal. Postocular fixigena triangular in outline, width (tr.) approximately 0.8 occipital lobe 

width. Posterior border furrow deep, straight, offset posteriorly from occipital furrow. Eye ridge 
28 LATE CAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

absent. Palpebral lobe lunate, flat, below level of 

interocular fixigena, length (exsag.) 0.5 glabellar 

length, centered anterior to .glabellar midpoint opposite anterior part of L2. Anterior end palpebral 

lobes opposite S4, posterior end opposite Sl. Preocular facial sutures subparallel to anterior border, 

converging diagonally across anterior border to midline. Postocular facial sutures divergent, straight. 

Librigena narrow, margin evenly rounded. Genal 

field gently convex, well differentiated from raised 

lateral and posterior borders by deep marginal furrows. Lateral border furrow and posterior border 

furrow confluent at corner angle, lateral furrow continuous, faintly impressed onto genal spine. Genal 

spine approximately two-thirds librigenal length 

( exsag.) Inner spine angle approximately 90°. 

Thorax and pygidi urn unknown. 

Prosopon consists of anastomosing ridges on the 

cranidium except in furrows which are smooth. 

Large cranidia (approx 8 mm long) have ridges 

grading to granules with irregularly shaped bases on 

the adaxial part of the glabella and occipital ring. 

Smaller cranidia (approx 4 mm long) lack granules, 

and the anastomosing ridges cover the entire dorsal 

surface. The only librigena attributed with certainty 

has faint anastomosing ridges on the genal field and 

lateral border. Weak development of ridges on the 

librigena may result from poor preservation. 

Discussion.-"Calvinella" prethoparia Longacre 

was originally described from the Saukiella serotina 

Subzone of the Wilberns Formation of central Texas. 

Cranidia from the Whitehall Formation attributed 

to the species differ from the Texas material in 

possessing granular prosopon which is more adaxially restricted and absent from the anterior border. 

This difference is not considered of taxonomic 

significance. 

The holotype of C. prethoparia (see Longacre, 

1970, pl. 6, fig. 7) is an internal mold having S2 furrows that connect across the midline. The depth of 

impression of S2 is greater on the holotype than on 

the New York material. This character-state may 

be related to instar size because smaller cranidia 

tend to have more weakly developed S2 furrows than 

do larger cranidia. The holotype is more than twice 

as long as the largest cranidium illustrated here. 

"Calvinella" prethoparia differs considerably from 

material attributed to Calvinella spiniger (Hall), 

the type species of Calvinella. (See Ulrich and Resser, 1933, pl. 37, 38.) Major differences in cranidial 

structure in "C." prethoparia include: parallel rather than divergent preocular facial sutures; wide, 

flat, interocular fixigenae rather than narrow, 

abaxially upsloping fixigenae; triangular posterior 

fixigenae, rather than subparallel sided; and relatively short ( exsag.) palpebral lobes that are centered anterior to the glabellar midpoint opposite L2, 

rather than long palpebral lobes that center behind 

the glabellar midpoint opposite Sl. This combination 

of differences is sufficient to establish a new genus 

of Saukiinae based on Calvinella prethoparia Longacre. However, such action is held in abeyance pending a comprehensive reevaluation of the existing 

saukiinid genera. 

Occurrence.-Saukiella serotina Subzone at localities H-1 and H-3, lower Whitehall Formation, 

Washington County, N.Y. 

Genus PROSAUKIA Ulrich and Resser, 1933 

Prosaukia Ulrich and Res,ser, 1933, p. 137; Lochman, in 

Harrington and others, 1959, p. 0324; Longacre, 1970, 

p. 47. 

Type species.-Dikelocephalus misa Hall, 1863, by 

original designation. 

Discussion.-The original diagnosis of Prosaukia 

given by Ulrich and Resser ( 1933) provided few 

features that are not also characteristic of the other 

genera of the Saukiinae. Lochman (in Harrington 

and others, 1959) gave an improved diagnosis, 

which was later slightly modified by Longacre 

( 1970). In summary, Prosaukia has been distinguished by the presence of an anteriorly tapering 

glabella, convex preglabellar field, an anterior border 

furrow that shallows transversely across the midline, 

and librigenae with lateral and posterior border furrows that are not confluent and extend subparallel 

distally along the genal spine. Forms have been included in the genus which have prosopon described 

or illustrated as smooth, granular, or consisting of 

anastomosing ridges. 

Species have been assigned to Prosaukia that show 

exceptions to the characteristics normally used to 

differentiate the genus. For example, Prosaukia 

curvicostata Ulrich and Resser, 1933, possesses a 

parallel-sided, anteriorly rounded glabella and an 

anterior border furrow that is evenly impressed 

across the midline. In addition, most species assigned to Prosaukia have librigenae with nonconfuent border furrows. At least one exception is 

Prosaukia delecostata Ulrich and Resser ( 1933, pl. 

26, fig. 15) in which the furrows are confluent. General problems related to the artificiality of the saukiinid genera are discussed under the heading "Subfamily Saukiinae." 
SYSTEMATIC PALEONTOLOGY 29 

"Prosaukia" spinula Taylor, n. sp. 

Plate 2, figures 15-20 

Types.-Holotype cranidium, USNM 186598; 

para type cranidia, USNM 186599 and 186600; paratype librigena, USNM 186602; para type pygidium, 

USNM 186603, all from locality H-1. Paratype pygidium, USNM 186601 from locality H-3. All type 

specimens are from the lower Whitehall Formation, 

Washington County, N.Y. 

Material available.-Ten cranidia, 15 librigenae, 

and three pygidia from locality H-1; 10 cranidia, 

six librigenae, and six pygidia from locality H-3; 

13 cranidia, seven librigenae, and three pygidia from 

locality 470b; and three librigenae and one pygidium 

questionably assigned from locality 473f. 

Diagnosis.-A species of saukiinid trilobite with 

a pygidium having a single short posteriorly directed 

median marginal spine, an axis greater than onehalf of the pygidial length and a glabella with bertillion pattern prosopon. 

Description.-Cranidium subrectangular in outline, moderately convex. Glabella trapezoidal in outline, anteriorly truncate, length approximately equal 

to basal width; sides straight, slightly tapered anteriorly from L1; L1 bowed outward slightly. Axial 

furrows well defined, deeply impressed. Anterior 

glabellar furrow shallower at midline than at anterolateral corners of glabella. Two pairs lateral 

glabellar furrows. 81 concave, deeply impressed 

laterally, becomes faintly impressed adaxially, faintly connected across midline on small holaspids, not 

connected on large holaspids, may connect on internal molds of large holaspids. 82 straight, faintly 

impressed laterally, not connected across midline. 

Occipital ring simple, straight, with medial node. 

Occipital furrow curved forward slightly at midline. 

Frontal area length (sag.) 0.2 cranidiallength, subhorizontal. Anterior border slightly raised, poorly 

differentiated by shallow anterior border furrow. 

Preglabellar field convex, length (sag.) about 0.5 

anterior border length (sag.). Anterior fixigena 

evenly downsloping. Interocular fixigena gently upsloping laterally, width (tr.) 0.3 adjacent glabellar 

width. Posterior fixigena relatively short (tr.), subparallel sided. Eye ridge absent. Palpebral lobes 

lunate, length ( exsag.) 0. 7 glabellar length, flat, subhorizontal, below level of interocular fixigena, centered posterior to glabellar midpoint opposite Sl. 

Preocular facial sutures weakly divergent to anterior 

border furrow, becoming strongly convergent and 

coursing diagonally across anterior border to midline. Postocular facial sutures divergent, sinuous. 

Librigena moderately convex, evenly rounded laterally. Genal field convex, well differentiated from 

lateral border by deep furrow. Lateral border raised, 

convex, continuous with long ( ?) genal spine. Lateral 

and posterior border furrows deeply impressed, connected at corner angle, lateral furrow continuous 

distally onto genal spine. Inner spine angle about 

135°. 

Thorax unknown. 

Pygidium subcircular in outline, length about 0.9 

width, strongly convex transversely. Axis tapered, 

straight sided, length about 0.7 pygidiallength, four 

axial rings plus terminal piece, posteriormost ring 

poorly differentiated. Pleural fields strongly downsloping laterally, subequally divided by five furrows 

and ridges, furrows strongly backturned. Pleural 

fields change slope distally to form poorly differentiated gently downsloping border. Posterior margin 

of pygidium drawn out posteriorly into broadly 

pointed spine, length about 0.1 pygidial length, upturned slightly distally. Ventral doublure wide, 

reaching posterior end of axis (not observed anterolaterally). 

Cranidial prosopon consists of bertillion pattern 

on the occipital ring and posterior part of glabella 

decreasing in degree of definition anteriorly, and 

faint bertillion pattern on the anterior fixigena. 

Other areas of cranidi urn smooth. Internal molds 

smooth. 

Librigena with complex anastomosing ridges on 

genal field, lateral border, posterior border, and 

genal spine. Anastomosing ridges faint on internal 

molds. 

Pygidium with anastomosing ridges on axis, 

pleural regions, and border oriented more or less 

parallel to margins. Internal molds of pygidium 

smooth. 

Discussion.-" Prosaukia" spinula n. sp. is placed 

in "Prosaukia" because of the presence of a convex 

preglabellar field, a slightly forward-tapering glabella, and an anterior border furrow that shallows 

across the midline. The attributed librigenae are 

similar to forms usually assigned to Calvinella in 

possessing lateral and posterior border furrows that 

merge at the corner angle and continue on to the 

genal spine as an extension of the lateral furrow. 

Librigena assigned to "Prosaukia" usually have lateral and posterior border furrows that do not become 

confluent at the corner angle. 

Rasetti (1946, p. 541, pl. 1, figs. 17-19) reviewed 

Saukia eboracensis Resser, 1942, on the basis of 
30 LATE CAM.BRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

additional material collected from the type locality 

in the Hoyt Limestone, one mile northwest of Saratoga Springs, N.Y. He reassigned the species to 

Prosaukia on the basis of attributed cranidia which 

have convex preglabellar fields. The attributed cranidia are similar to those here assigned to u Prosaukia" spinula. Differences include adaxially disconnected, rather than connected, S2 furrows and 

weaker development of cranidial prosopon in "P." 

spinula. The greatest differences between the two 

species are shown by the attributed pygidia. The 

holotype pygidium of Prosaukia. eboracensis is wider than long, possesses five axial rings rather than 

four, and lacks the strongly backturned pleural furrows and posterior marginal spine characteristic of 

uP." spinula. 

Lochman (1946, p. 549, pl. 1, figs. 1-6) described 

and illustrated Prosaukia briarcliffensis from weathered dolomite outcropping 1~ miles south of Pine 

Plains, Dutchess County, N.Y. The specimens, although fragmentary, are similar to material assigned to "P." spinula in possessing librigenae with 

anastomotic ridges on the genal field. The cranidium 

of P. briarcliffensis has S1 furrows that do not connect across the midline. However, the furrows are 

relatively deeply impressed laterally, as in "P." 

spinula, so that the faint connection of S1 furrows 

in "P." spinula may not be a significant difference. 

The pygidium attributed to P. briarcliffensis is similar to "P." spinula in having a circular outline, backturned pleural furrows, similar axial taper, and 

number of axial rings. Unfortunately the posterior 

part of the border region and margin is broken so 

that only the ventral doublure is preserved. The 

specimen is oriented in the matrix in such a way 

that presence or absence of a posterior spine cannot 

be determined. Allowing for uncertainties of preservation, the greatest apparent difference between 

"P." spinula and P. briarcliffensis is in the presence 

of bertillion prosopon on the glabella of the former 

and coarse granular prosopon on the glabella of the 

latter. 

Cranidia assigned to "P." spinula are remarkably 

similar to the type cranidia of Saukiella set·otina 

Longacre (1970, pl. 6, figs. 1-3). However, she did 

not illustrate a librigena or pygidium, so that critical 

comparison is not presently possible. Longacre 

(1970, p. 53) placed Saukiella norwalkensis of Winston and Nicholls (1967, pl. 11, figs. 6-8, 12) in 

synonomy with S. serotina. The librigena illustrated 

by Winston and Nicholls (fig. 7) is of the "typical 

Saukiella form" with a slightly advanced genal spine 

and deep confluent border furrows that do not extend 

onto the genal spine. The cranidia illustrated by Winston and Nicholls (figs. 6, 8) differ from those 

illustrated by Longacre in having more forwardtapering glabellae and relatively wider preglabellar 

fields. These observations lead to the question whether the librigena placed in synonomy with S. serotina 

is indeed correctly attributed. Because of this uncertainty, the relationship between "P." spinula and S. 

serotina cannot be satisfactorily resolved at present. 

The pygidia and librigenae here attributed to 

"Prosaukia" spinula are most similar to Calvinella 

americana Kobayashi, 1935 [ = Calvinella walcotti 

Ulrich and Resser, 1933; not Calvin ella walcotti 

(Mansuy, 1915)] from the Upper Cambrian of Wisconsin. (See Ulrich and Resser, 1933, pl. 40, figs. 

1-14.) The pygidium attributed to C. americana is 

subcircular in outline with the posteriormost part of 

the margin upturned as in "P." spinula. In all available specimens of C. americana, the area occupied 

by the pygidial spine is broken away, and it cannot 

be definitely stated that it was originally present. 

However, fossil preservation is such in the C. americana sample, that specimens split out of the matrix 

along partings parallel to the bedding. As the pygidial spine would have been upcurved it would tend 

to be in a higher plane than the main part of the 

pygidium, thus potentially becoming easily broken 

when the rock was split. In all specimens observed 

(for example, Ulrich and Resser, 1933, pl. 40, figs. 

11-14, 20) the region of the base of the pygidial 

spine appears roughened as if part was broken 

away. Because of these facts, I conclude that the 

pygidium of C. americana probably possessed a terminal spine. 

The pygidium assigned to "P." spinula differs 

from C. americana in possessing more sharply backturned plJural furrows and an axial length to 

pygidial length ratio of less than 0.5. 

Librigenae attributed to C. americana by Ulrich 

and Resser ( 1933) are similar to forms here attributed to "P." spinula. Both have marginal furrows that become confluent at the corner angle and 

in which the lateral furrow continues undeflected on 

to the genal spine. The "cotype" librigena illustrated 

by Ulrich and Resser on their plate 40, figure 9, has 

prosopon preserved on the genal field which consists of anastomosing ridges, although this feature 

is not shown in their illustration. Such prosopon is 

virtually identical with that on the genal fields of 

librigenae here attributed to "P." spinula. 
SYSTEMATIC PALEONTOLOGY 31 

In contrast to the librigena and pygidium, cranidia attributed to "P." spinula and C. americana 

are distinctly different. "Cotype" cranidia of C. 

americana all show a lack of a preglabellar field, 

presence of an evenly impressed anterior border 

furrow, and an occipital spine. Ulrich and Resser 

( 1933, p. 236) described C. americana as "usually 

quite smooth, only rarely showing evidence of minute tuberculation." Examination of the type material shows that the specimens have been worn so 

much, probably since Ulrich and Resers' study, that 

original prosopon cannot be verified with certainty. 

The cranidium illustrated by Ulrich and Resser on 

their plate 40, figure 1, seems to show a granular 

prosopon. In contrast, cranidia assigned to "P." 

spinula have convex preglabellar fields, adaxially 

shallowing anterior border furrows, and absence of 

occipital spines. 

An argument could be made for assigning "P." 

spinula to Calvinella on the basis of morphological 

similarity to C. americana. However, I have chosen 

to place more taxonomic weight on features of the 

cranidium, the structure of which is most consistent 

with the tentative operational concept of Prosaukia. 

Occurrence.-Saukiella serotina Subzone at localities H-1, H-3, 470b, and questionably 473f, from 

Washington County, N.Y. 

Family SOLENOPLEURIDAE Angelin, 1854 

Genus HYSTRICURUS Raymond, 1913 

Hystricurus Raymond, 1913, p. 60; Ross, 1951, p. 39; Hintze, 

1953, p. 164; Sando, 1957. p. 136. 

Type species.-Bathyurus conicus Billings, 1859, 

by original designation. 

Discussion.-The generic concept of Hystricurus 

given by Ross (1951) is followed here. 

Hystricurus millardensis Hintze 

Plate 3, figures 10-16 

Hystricurus millardensis Hintze, 1953, p. 168, pl. 6, figs. 17-

21; Winston and Nicholls, 1967, p. 76, pl. 12, figs. 14, 

18; Stitt, 1971, p. 46, pl. 8, figs. 17, 18. 

Material available.-Fourteen cranidia, two incomplete librigena, and one pygidium from locality 

H-2. 

Description of Whitehall material.-Cranidium 

subrectangular in outline, strongly convex. Glabella 

conical, tapered forward, anterior end bluntly 

rounded, length 0.6 cranidiallength, length 0.9 basal 

glabellar width. Axial glabellar furrows deeply impressed laterally, less deeply impressed anteriorly, 

fossulae present at anterolateral corners of glabella. 

Lateral glabellar furrows expressed as oval-shaped 

regions without prosopon in position of S1 and S2. 

Occipital ring simple, straight, well defined by deep 

occipital furrow. Medial region of occipital ring 

lacking node or spine. Frontal area length 0.2 cranidial length (sag.). Preglabellar field sagittally 

convex, downsloping. Anterior border convex, evenly rounded in lateral profile, length (sag.) about 0.5 

preglabellar field length (sag.). Anterior margin 

evenly rounded in dorsal view. Anterior fixigena 

strongly downsloping anterolaterally. Interocular 

fixigena convex, below level of glabellar surface at 

midline, width 0.45 adjacent glabellar width. Posterior fixigena subtriangular, width (tr.) 0.75 width 

(tr.) occipital ring. Eye ridge weakly developed. 

Palpebral lobe lunate, subhorizontal, raised above 

level of interocular librigena, length (exsag.) 0.45 

glabellar length, centered opposite L2. Facial sutures 

opisthoparian. Preocular sutures divergent, straight, 

directed downward anterolaterally. Postocular suture strongly divergent, nearly straight. 

Librigena known from fragments, ellipsoidal in 

outline, strongly convex. Genal field evenly convex, 

strongly downsloping. Eye socle raised above level 

of genal field. Lateral border strongly convex, 

strongly differentiated by deep lateral furrow. Genal 

spine not observed. 

Thorax unknown. 

Pygidium subelliptical in outline, strongly convex, 

length (sag.) 0.5 width. Axis convex, strongly tapering posteriorly to border. Four axial rings and 

terminal piece, fourth ring weakly differentiated. 

Pleural regions strongly downsloping, three pairs 

moderately deep interpleural furrows, two pairs 

moderately shallow pleural furrows. Border defined 

by change in slope from pleural regions, not crossed 

by pleural furrows. 

Cranidial prosopon consists of large closely spaced 

perforate granules, except in furrows and on the 

border. Fine closely spaced granules are interspersed 

between large granules and occupy furrows. The 

anterior border has well-developed terrace lines on 

the distal side and a few scattered granules on the 

proximal side. 

The single librigena has large closely spaced perforate granules on the genal field and fine closely 

spaced granules in the border furrow. The border 

possesses a few granules on the proximal side and 

terrace lines on the distal side. Genal caeca are faintly visible radiating from the base of the eye socle 

into the border furrow. Caeca are under, rather 

than between, large perforate granules. 
32 LATE CAMBRIAN AND EARLY ORDOVICIAN TRILOBITES, EASTERN NEW YORK STATE 

The pygidium has large perforate granules more 

widely spaced than on the cranidia and librigena. 

Interspaces contain fine closely spaced granules. 

Axial rings possess an additional pair of relatively 

large granules symmetrical about the sagittal plane. 

Terrace lines are present on the border. 

Internal molds of cranidia have scattered fine pits. 

Discussion.-Hystricurus milla1·densis was originally described from the lower part of Symphysurina 

B Zone in the House Limestone of the Southern 

House Range, west-central Utah (Hintze, 1952). 

The Whitehall specimens differ from the House 

material in possessing granular prosopon on 

librigenae. 

Winston and Nicholls (1967) attributed material 

to H. millardensis from the Symphysurina Zone of 

the Wilberns Formation, central Texas. The only 

observed difference between Whitehall and Wilberns 

specimens is the apparent absence of granule-free 

glabellar furrow areas in the Texas material. 

Stitt ( 1971) attributed specimens from the Symphysurina Zone at the base of the McKenzie Hill 

Limestone of south-central Oklahoma to H. millardensis. The Oklahoma material differs from Whitehall 

specimens in lacking granule-free glabellar furrow 

areas and in possessing granules rather than pits on 

surfaces of internal molds (Stitt, 1971, p. 46). 

These differences are not considered taxonomically 

significant. 

Flower (1969, p. 33, pl. 7, fig. 4) described and 

illustrated a cranidium from the Fort Ann Limestone, east of Smith Basin, N.Y., which he assigned 

to Hystricurus cf. conicus (Billings). The cranidium 

differs from material known from the Whitehall 

Formation in having a less tapered glabella, less 

deeply impressed fossulae, and coarse-textured 

granular prosopon. 

Occurrence.-Missisquoia Zone, locality H-2, upper Whitehall Formation, Washington County, N.Y. 

DESCRIPTION OF FOSSIL LOCALITIES 

All fossil localities studied are described below 

with reference to the southwest quarter of the 

Whitehall 71;2-minute quadrangle, New York-Vermont, 1950 edition, Washington County, N.Y. Coordinates are given following a system often used 

by Franco Rasetti, where the abscissa(x) and ordinate (y) are given in millimeters from the origin 

at the lower left, southwest corner of the map. Color 

designations are based on the "Rock-Color Chart" 

of the National Research Council (Goddard, 1948). 

H-1.-Lower Whitehall Formation. Sample composed of light- to medium-gray (N 5-7) ooidskeletal grainstone collected at the east end of 

Crossman quarry (inactive), near the road entrance to the quarry, in place 11 feet above quarry 

floor. Crossman quarry is on the north side of 

Washington County Route 10 (Sciota Road) and 

the south side of a low hill immediately south of 

Finch Marsh. Map coordinates, x = 396, y = 323. 

Collected by R. B. Halley, July 7, 1970. Filed in the 

U.S. Geological Survey collections in Washington, 

D.C., under number 7602-CO. 

H-2. Upper Whitehall Formation. Sample composed 

of medium-gray (N 5) lime mudstone collected in 

place from the southwest corner of Warner Hill, 

at about 400 feet elevation, north of Finch Marsh. 

Map coordinates, x = 398, y = 378. Collected by R. 

B. Halley, June 16, 1970. Filed in the U.S. Geological Survey collections in Washington, D.C., 

under number 7603-CO. 

H-3.-Lower Whitehall Formation. Sample composed of light- to medium-gray (N 5-7) ooidskeletal grainstone collected in place from the 

northwest side of Warner Hill, about 800 feet 

southeast from cluster of buildings immediately 

east of School House Marsh, between 200 and 

300 feet elevation. Map coordinates, x = 404, 

y=413. Collected by R. B. Halley, June 16, 1970. 

Filed in the U.S. Geological Survey collections in 

Washington, D.C., under number 7604-CO. 

418e (old series) .-Sample composed of light- to 

medium-gray skeletal packstone collected "two 

miles north-northeast of Whitehall, New York," 

by C. D. Walcott, date unknown. Locality data are 

insufficient for determining the precise collecting 

locality. The sample may have come from either 

the Crossman quarry area along Washington 

County Route 10, or Warner Hill. (See fig. 1 for 

general location.) 

U.S. Geological Survey files contain a copy 

of the Whitehall, New York-Vermont, 15-minute 

quadrangle, 1902 edition, used by Josiah Bridge 

to record the location of fossil collections 470b, 

470bl and 473f. These localities were replotted on 

the southwest quarter of the Whitehall 71/2-

minute quadrangle, 1950 edition, and coordinates 

were determined which are given below. 

470b (old series) .-Sample composed of mediumgray (N 5-6) ooid-sk:!letal grainstone and packstone. "Hall farm, one mile northeast of Whitehall, N.Y. All material except 'crytozoans' from 
REFERENCES CITED 33 

one boulder." Replotted map coordinates, x = 381, 

y=295. Collected by E. 0. Ulrich, Rudolph Ruedemann, and Josiah Bridge, July 8, 1931. 

470bl (old series) .-Sample composed of mediumgray (N 5-6) ooid-skeletal grainstone. Location 

same as 470b except: "100 feet above 470b." Replotted map coordinates, x = 386, y = 292. 

473f (old series) .-Sample composed of medium 

gray (N 4-6) ooid grainstone and boundstone 

from Finch farm, at bend in road one-eighth of a 

mile east of E. A. Martin house. One loose block. 

Replotted map coordinates, x=389, y=321. Apparently collected a few feet west of the entrance 

to Crossman quarry. Collected by E. 0. Ulrich, 

Rudolph Ruedemann, and Josiah Bridge, July 8, 

1931. 

7098-CO.-Upper Whitehall Formation. Sample 

composed of light- to medium-gray (N 6-7) ooidlithoclast grainstone collected near top of Skene 

Mountain at junction of foot trail and a line bearing S. 10° E. for about 100 yards from a red communications tower located at the high point on 

the mountain. Collected in place from limestone 

beds forming blocky outcrops on dip slope overlying sandy and cherty dolomite beds. Map coordinates, x=348, y=260. Collected by M. E. 

Taylor and J. E. Taylor, September 23, 1971. 

7099-CO.-Same locality and rock type as 7098-CO 

except different bed, one foot lower in section. 

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Cambro-Ordovician trilobites from the Marathon uplift, west Texas: Jour. Paleontology, v. 30, no. 6, p. 

1341-1349. 

Winston, D., and Nicholls, H. 1967, Late Cambrian and 

Early Ordovician faunas from the Wilberns Formation 

of central Texas: Jour. Paleontology, v. 41, no. 1, p. 

66-96. 

Wright, C. W. 1950, Comment on proposal rto substitute 

Prosopon for ornament: Jour. Paleontology, v. 24, no. 

4, p. 497. 
INDEX 

[Italic paee numbers indicate major references and descriptions] 

Paee: 

A 

Acheilops -------------------------- 7, 17, 19 

dilatus ---------------------------- 19 

masonensis ------------ 4, 5, 7, 16, 19; pl. 1 

norwalkensis ---------------------- 19, 20 

Acknowledgments -------------------- I 

Age and correlations ------------------ 4 

Agraulos saratogensis ---------------- 25 

americana, Arethusina --------------- 21 

Calvinella ------------------------ 30, 31 

Analysis methods -------------------- 18 

Apoplanias --------------------------- 8 

apopsis, Corbinia --------------------- 6, 7 

arbucklensis, Plethopeltis -------------- 25 

Arethusina americana ----------------- 21 

armatus, Bathyurus ------------------ 23 

Assemblages dissimilar to Whitehall 

fauna -------------------- 16 

Asemblages similar to Whitehall 

fauna 18 

B 

Bathyurus conicus ------------------- 31 

Bibliography -------------------------- 33 

Biofacies distribution ----------------- 11 

Biostratigraphie studies --------------- 4 

Biostratigraphy ----------------------- 4 

Bowmania ------------------------- 7,17, U 

pennsylvanica -------- 4, 5, 7, 16, S1; pl. 2 

Briarcliff Do~omite ------------------- 6 

briarcliffensis, Prosaukia --------------- 6, 3•0 

0 

Calvinella -------------------- 6, 7, 17, ~7. 29 

americana ----------------------- 30,31 

prethoparia -------------- 4, 5, 6, !7; pl. 2 

spiniger -------------------------- 28 

walcotti -------------------------- 30 

Cambrian-Ordovician boundary ------- 8 

Catillicephalidae ---------------------- 18 

Clelandia ----------------------------- 7 

Composition of Whitehall fauna ----- 4 

conicus, Bathyurus -------------------- 31 

Hystricurus ---------------------- 32 

Conococheague Limestone of 

Maryland -------------- 6, 15, 21 

convergens, Plethometopus ------------ 25 

Corbinia apopsis ---------------------- 6, 7 

Subzone ------------------- 7,8,9,20,24 

Correlations and age ----------------- 4 

Crossman quarry --------------- 2, 4, 6, 9, 33 

curvicostata, Prosaukia --------------- 28 

D 

delecostata, Prosaukia ---------------- 28 

depressa, Missisquoia ----------------- 22 

Description of fossil localities --------- 8~ 

Dikelocephalidae ---------------------- 27 

Dikelocephalus misa ------------------ 28 

spiniger --------------------------

dilatus, Acheilops ---------------------

27 

19 

Dirachopea sp 

Distribution of biofacies 

E 

eboracensis, Prosaukia --------------- 30 

Saukia --------------------------- 29 

Eminence Do:omite of Missouri ------ 6, 15 

Environmental setting ___ ------------- 9 

Environments, inferred ___ ----------- 10 

Euptychaspis ----------------------- 7, 17, S6 

typicalis ----------------- 4, 5, 7, 26; pl. 2 

sp ------------------------------- 4, 5 

F 

Fort Sill Formation 6 

Fossil collections --------------------- I 

Fossil localities, description ----------- IS 

Fossils, other, from Whitehall fauna__ 4 

G 

Garden City Formation -------------- 8 

Gastropods --------------------------- 4 

Geologic setting ---------------------- 1 

granulosa, Plethopeltis ---------------- 25 

H 

Hedinaspis fauna ---------------------

Heterocaryonidae ______ ----------------

Highgate Formation ------------------

Highgatella ___ ----------------------- H omagnostus 

House Limestone ---------------------

Hoyt Limestone ---------------------

Hoyt Member of Whitehall Formation __ 

18 

21 

6, 23 

7, 8 

7, 8 

8, 32 

6, 30 

2 

Hungaia magnifica fauna ---------- 6, 16, 18 

Hyolithoids -------------------------- 4, 5 

Hystricurus ----------------------- 4, 7, 8, 81 

conic?ts --------------------------- 32 

millardensis ----------- 4, 5, 7, 8, 81; pl. 3 

sp. D ---------------------------- 8 

I 

lllaenttrus Zone ---------------------- 17 

Index of faunal resemblance 13 

J 

.Jujuyaspis ---------------------------- 7 

juma, Saukiella --------------------- 5, 7, 26 

K 

Kittatinny Limestone ----------------- 15 

knopfi, Plethometopus ---------------- 6, 24 

L 

Lytospira sp 6 

M 

magnifica, Hungaia 6, 16, 18 

masonensis, Acheilops ___ 4, 5, 7, 16,19; pl. 1 

Matherella 

sp ------------------------------- 5 

Matthevia --------------------------- 4, 6 

sp ------------------------------- 5 

Methods and problems --------------- 4 

Methods of analysis ----------------- 18 

millardensis, Hystricurus __ 4, 5, 7, 8, 81; pl. 3 

misa, Dikelocephalus ___ -------------- 28 

Missisquoia --------------------- 2, 5, 7, 8, 22 

depressa -------------------------- li!2 

typicalis ------------ 4, 5, 6, 7, 8, 22; pl. 3 

Zone -------------------------- 6, 22, 32 

Missisquoiid!ae ------------------------ 22 

Models ------------------------------- 11 

modestus, Plethometopus ------------- 24 

Morphological terminology ------------ 18 

Murchisonia sp ---------------------- 6 

N 

norwalkensis, Acheilops ------------- 19, 20 

Saukiella ------------------------- 30 

Notch Peak Limestone ------------- 8, 13, 23 

nuculiti!ormis, Ribeiria -------------- 2, 4, 5 

0 

Objectives ___ ------------------------

obtusus, Plethometopus ------ 4, 5, 7, ~4; pl. 1 

Osceolinae --------------------------- 27 Other fossils from Whitehall fauna ___ 4 

p 

Parabolinella 

Parakoldinioidia 

typical is _________ ------- ________ _ 

Pelagiella _______________ --------------

7 

2,22 

22 

6 

pennsylvanica, Bowmania _ 4, 5, 7, 16, 21; pl. 2 

Petrology ----------------------------- 9 

Plethometopus -------------- 7, 16, 17, 28,25 

convergens ------------------------ 25 

knopfi --------------------------- 6, 24 

modestus ------------------------- 24 

obtusus ----------------- 4, 5, 7, 24; pl. 1 

sp. A ------------------- 4, 5, 7, 24; pl. 1 

Plethopeltidae ------------------------ 23,25 

Plethope/tis ---------------- 4, 7, 8, 16, 17,25 

arbucklensis ---------------------- 25 

granulosa ------------------------ 25 

sp ------------------------ 4, 5, 25; pl. 1 

Pleurotomariacean gen. indet --------- 5 

Potsdam Formation ------------------- 2 

Potsdam limestone -------------------- 6 

prethoparia, Calvinella ---- 4, 5, 6, 7, 27; pl. 2 

Previous work ----------------------- I 

Problems and methods --------------- 4 

Prosaukia ------------------- 7, 16, 17, 27,28 

briarcliffensis --------------------- 6, 30 

curvicostata ---------------------- 2S. 

delecostata ------------------------ 28 

eboracensis ----------------------- 30 

spinula ------------------ 4, 5, 7, 29; pl. 2 

Ptychaspididae ----------------------- 26 

Ptychaspidinae ----------------------- 26 

pyrene, Saukiella -------------------- 5, 7 

37 
38 

Paae: 

R 

Ribeiria nuculitifarmis --------------- 2, 4, 5 

sp ------------------------------- 4, 5 

s 

saratogensis, Agraulos ---------------- 25 

Saukia ------------------------------ 5, 7 

ebaracensis ---------------------- 29 

Zone ------------------- 5, 6, 9, 13, 21, 26 

Saukiella junia --------------------- 5, 7, 26 

Subzone ----------------------- 6, 20, 26 

norwalkensis --------------------- 30 

pyrene --------------------------- 5, 7 

Subzone ---------------------- 25 

serotina ------------------------ 5, 7, 30 

Subzone __ 6, 9, 20, 22, 24, 25, 26, 28, 31 

Saukiinae ---------------------------- !7, 28 

Schizopea sp. A --------------------- 5 

sp B ---------------------------- 15 

sp ------------------------------- 4 

serotina, SaukieUa ------------------ 5, 7, 30 

Signal Mountain Formation ---------- 5,13 

U.S. GOVERNMENT PRINTING OFFICE: 1974 0-527-763 

INDEX 

Signal Mountain Limestone 

Sinuopea sp --------------------------

Skene Member of Whitehall Formation 

Paae. 

8, 23 

5 

2 

Skene Mountain ------------------- 3, 4, 6, 9 

Solenopleuridae ---------------------- 31 

spinifera, Stenochilina ---------------- 20, 21 

spiniger, CalvineUa ------------------ 28 

Dikelocephalus -------------------- 27 

spinula, Prosaukia ----------- 4, 5, 7, !9; pl. 2 

Stenochilina ------------------- 4, 6, 7, 17,10 

spinifera ------------------------ 20, 21 

sp. A --------------------4, 5, 7, tO; pl. 1 

Stenopilus ---------------------------- 25 

Stratigraphy of the Whitehall area --- 2 

Summary ----------------------------- I 

Survey Peak Formation --------------- 8 

Symphysurina ------------------------ 7, 8 

B -------------------------------- 7 

Zone --------------------------- 7, 8, II 

Systematic paleontology -------------- 18 

T 

Tellerina 27 

Paae 

Ticonderoga Formation ---------------- 2 

Trempealeauan fossils ---------------- 2, 16 

Trempealeauan Stage ---------------- 15, 25 

Triaf'thropsis ------------------------- 20 

Triblidium -- ------------------------- 6. 

Trilobita ----------------------------- 18 

Tri!obites ---------------------------- -' 

Tub Mountain ----------------------- 9 

typicalis, Euptychaspis ------- 4, 5, 7, 26; pl. 2 

Missisqucna --------- 4, 5, 6, 7, 8, u; pl. 3 

Parakoldinioidia ------------------ 22 

w 

Whitehall tauna, assemblages similar to 18 

Whitehall fauna, composition -------- -' 

Whitehall Formation -------- 1, 6, 8, 9, 22, 32 

Wilberns Formation of Texas ---- 5, 7, 13,22 

walcotti, CalvineUa ------------------- 30 

Warner Hill ------------------- 2, 6, 8, 9, 32 

Whipple Cave Formation -------------- 13 

Whitehall fauna, assemblages 

dissimilar ---------------- 11 
PLATES 1-4 

Contact photographs of the plates in this report are available, at cost, from U.S. 

Geological Survey Library, Federal Center, Denver, Colorado 80225. 
PLATE 1 

FIGURES 1-3. Plethopeltis sp. indet. (p. 25). 

1. Internal mold of cranidium, USNM 186578, X 2.8, loc. H-3. 

2, 3. C!anidium, USNM 186579, X 6.5, loc. H-3, latex external 

cast and peripheral part of same cranidium. 

4, 5. Acheilops masonensis Winston and Nicholls (p. 19). 

4. Librigena, USNM 186580, X 8.7, loc. 470b. 

5. Granidium, USNM 186581, X 6.2, loc. H-3. 

6-10. Stenochilina sp. A (p. 20). 

6, 7, 9. Cranidium, USNM 186582, X 6.3, loc. 418e, lateral, anterior, and dorsal views. 

8. Granidium, USNM 186583, X 6.7, loc. 418e. 

10. Cranidium, USNM 186584, X 5.5, loc. 418e. 

11-14. Plethometopus obtusus Rasetti (p. 24). 

11-13. Granidium, USNM 186585, X 4.5, loc. 473f, lateral, anterior, and dorsal views. 

14. Cranidium USNM 186586, X 5.2, loc. 473f. 

15-17. Plethometopus sp. A (p. 24). 

Cranidium, USNM 186587, X 6.3, dorsal, anterior, and lateral 

views, loc. 473f. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 PLATE 1 

2 

11 

13 14 

16 17 

PLETHOPELTIS, ACHE/LOPS, STENOCHILINA, AND PLETHOMETOPUS 
PLATE 2 

FIGURES 1-3. "Calvinella" prethoparia Longacre (p. 27). 

1. Librigena, USNM 186588, X 6.0, loc. H-1. 

2. Small cranidium, USNM 186589, X 7.7, loc. H-1. 

3. Large cranidium, USNM 186590, X 4.3, loc. H-3, specimen 

silicified on right side. 

4-11. Euptyckaspis typicalis Ulrich (p. 26). 

Figures 4-7, 10 from loc. H-3; figures 8, 9, 11 from loc. H-1. 

4. Cranidium, USNM 186591, X 5.8. 

5. Cranidium, USNM 186592, X 6.9. 

6, 7. Cranidium, USNM 186593, X 6.9, dorsal and anterior views. 

8, 9. Librigena, USNM 186594, X 6.1, lateral and dorsal views. 

10. Cranidium, USNM 186595, X 6.7. 

11. Pygidium, USNM 186596, X 7.4. 

12-14. Bowmania cf. B. pennsylvanica Rasetti (p. 21). 

Cranidium, USNM 186597, X 8.2, dorsal, anterior and lateral 

views, loc. H-1. 

15-20. "Prosaukia" spinula Taylor, n. sp. (p. 29). 

Figure 18 from loc. H-3; figures 15-17, 19,20 from loc. H-1. 

15. Holotype cranidium, USNM, 186598, X 6.2. 

16. Small paratype cranidium, USNM 186599, X 6.9. 

17. Paratype cranidium, USNM 186600, X 9.2. 

18. Latex cast of paratype pygidium, USNM 186601, X 4.2. 

19. Paratype librigena, USNM 186602, X 6.3. 

20. Paratype pygidium, USNM 186603, X 6.5. 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 PLATE 2 

15 18 20 

"CAL V/NELLA ," EUPTYCHASPIS, BOWMAN/A, AND "PROSA UK/A" 
PLATE 3 

FIGURES 1-9. Missisquoia typicalis Shaw (p. 22). 

Figures 1, 3 from loc. 7098.-CO; figures 2, 4, 8 from loc. 7099-

CO; figures 5-7, 9 from loc. 470bl. 

1. Cranidium, USNM 186604, X 12.0. 

2. Granidium, USNM 186605, X 12.0. 

3. Cranidium, USNM 186606, X 12.0. 

4. Cranidium, USNM 186607, X 13.0. 

5. Libtigena, USNM 186608, X 14.0. 

6. Librigena, USNM 186609, X 9.3. 

7. Cranidium, USNM 186610, X 12.5. 

8. Pygidium, USNM 186611, X 11.3. 

9. Cranidium, USNM 186612, X 11.1. 

10-16. Hystricurus millardensis Hintze (p. 31). 

Figu"es 10-16 from loc. H-2. 

10. Pygidium, USNM 186613, X 7.0. 

11-13. Cranidium, USNM 1866>14, X 4.2, anterior, lateral, and 

dorsal views. 

14. Librigena USNM 186615, X 5.8. 

15, 16. Cranidium, USNM 186616, X 4.5, anterior and dorsal 

views. 
GEOLOGICAL SURVEY 

1 

4 

8 

11 

13 

2 

5 6 

10 

14 

MISSISQUOIA AND HYSTR!CUR US 

PROFESSIONAL PAPER 834 PLATE 3 

3 

7 

9 

12 

15 

16 
PLATE 4 

[Bar is 0.5 mm long, except ilg. 3 in which bar is 0.13 mm long. All photomicrographs taken in 

plane-polarized light unless indicated otherwise] 

FIGURES 1-6. Lower Whitehall Formation, Crossman quarry. 

1. Oolitic grainstone composed of ooids, oolitically coated pellets, and skeletal fragments. 

2. Pelletal and lithoclastic grainstone containing minor amounts 

of quartz sand. 

3. Length-slow chalcedony from along the fenestral wall of a 

thrombolite, crossed polarizers. 

4. Thrombolite fenestra partly filled with internal pelleted sediment. 

5. Border between light and dark clots of thrombolite having a 

clastic internal texture. Spar-rich area (left) does not appear 

grain supported, and is dark gray in hand specimen. Area of 

closely packed pellets (right) appears light gray in hand 

specimen. 

6. Stromatolite laminations produced by variations in grain size. 

7. Echinoderm fragments characterized by serrate edges, single-crystal extinction, and syntaxial cement, Hoyt Limestone, Lester 

Park, Saratoga County, N.Y. 

8. Oblique section through fragment of dasycladacean alga, USNM 

186617, Hoyt Limestone, Lester Park, Saratoga County, N.Y. 

Dasyclads from ·the Hoyt were identified by John L. Wray 

(written commun. to Halley, 1970). 
GEOLOGICAL SURVEY PROFESSIONAL PAPER 834 PLATE 4 

PHOTOMICROGRAPHS OF PETROGRAPHIC THIN SECTIONS