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SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 152, NUMBER 4 ,
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Charles DB. and Mary Waux THalcott
Research Fund

LOWER AND MIDDLE CAMBRIAN
TRILOBITE FAUNAS FROM THE
TACONIC SEQUENCE OF
NEW YORK

(Wits 14 Pirates)

By
FRANCO RASETTI

Johns Hopkins University, Baltimore, Maryland
Honorary Research Associate, Smithsonian Institution

(Pustication 4710)

CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION PRESS
————-—- AU GUST 29; 1967 5

SMITHSONIAN MISCELLANEOUS COLLECTIONS
VOLUME 152, NUMBER 4

Charles BD. and Mary Waux Walcott
Research Fund

LOWER AND MIDDLE CAMBRIAN
TRILOBITE FAUNAS FROM THE
TACONIC SEQUENCE OF
NEW YORK

(Wire 14 Pirates)

By

FRANCO RASETTI

Johns Hopkins University, Baltimore, Maryland
Honorary Research Associate, Smithsonian Institution

(Pustication 4710)

CITY OF WASHINGTON
PUBLISHED BY THE SMITHSONIAN INSTITUTION PRESS
AUGUST 29, 1967

PORT CITY PRESS, INC.
BALTIMORE, MD., U. S. A.

CONTENTS

Page
Introduction and Acknowledgments. .....cccscccssessdsccccceuscesssecs 1
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ED CONES oe ta aks cin duce Madaieaen dba na Rakes intde 22
Systematic Descriptions:

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Pay Oe SRWAEe Wadates fas ak adbaes eeeea Teka eas eadcdu ee 26
WOES FIO ATL ASD esd ch cncdivech ta pbhObandnn ite kas bacewe 31
Pantie DIPL ANOS TEA isis cavd isthe wadiaeas venagedbadeas 35
PGE LE, cathe ss o3.co hav evabeocatadadas faiss G@ndaien 37

Se PPE RRMRITE Sad ab dnicelk ald BA@ud eas dbak ae SVEbe C3 Cee Led eas 40
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Penh tr eB ORT 5s oho | os cn gis dale hated Whee Cod Kemet 68
EY Mose ERI ranches <daen sank tenors ccdsnndeainetan 68

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eer mnaey GATES PRPC SAIUUR sia srevecesdccuscccssesieees 74

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PRN BAAN ROE, ccccesdnebhadduavvenssuebans biws 80
PEE SEE OEE, cata iis tie btn cs Vitada Cai owe bunkn dhmeenld 82
EE GHP IIE IEEE un veaeh Riek udoWwch aos tandupanhingas nene 87
ee Cee es BE TEPAIaEPPE ad Le cues tdencacinercesdcanees 87
eet RAUURRINOE Gk cdicaeeieds de ccavebcncdSresevechtanane 88
Susetiomily PARADOZRIDAGHA. (55 siadescadectvowsccedecdencnen 90
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Charles BD. and Mary Waux Walcott Research Fund

LOWER AND MIDDLE CAMBRIAN TRILOBITE
FAUNAS FROM THE TACONIC SEQUENCE
OF NEW YORK

By FRANCO RASETTI

Johns Hopkins University, Baltimore, Maryland
Honorary Research Associate, Smithsonian Institution

(Wire 14 Pirates)

INTRODUCTION AND ACKNOWLEDGMENTS

IN A PREVIOUS PAPER (Rasetti, 1966a) the writer described a new
faunule of Early Cambrian age discovered in bedded limestone of the
Taconic sequence in the East Chatham 7!4-minute quadrangle, Colum-
bia County, New York. The faunule was exceptional in the large
number of new genera and species of the trilobite family Eodiscidae,
exceeding the total formerly known for all of North America. This
finding stimulated an intensive search for fossils in Cambrian out-
crops in northern Columbia County, with highly gratifying results. A
greater variety of Early Cambrian faunules than previously known
from the Taconic sequence was discovered, and Middle Cambrian
trilobites belonging to two faunizones were collected, thereby proving
the existence of Cambrian strata of that age, contrary to the general
belief held by previous students of that area. For the first time in
the study of the Cambrian of the Taconic sequence, it was possible to
obtain several faunules in certain stratigraphic order from a single
section. Study of the Middle Cambrian faunas allowed a very precise
correlation of the strata with those of northern Europe and the
western United States.

This paper is essentially based on the results of stratigraphic studies
and fossil collecting in northern Columbia County. However, com-
parisons with strata and fossils in the more northerly parts of the
Taconic sequence, in Rensselaer and Washington Counties, are occa-
sionally made, even though those areas were by far not as thoroughly

SMITHSONIAN MISCELLANEOUS COLLECTIONS, VOL. 152, NO. 4

2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

explored by the writer. The early work of Ford, Dale, and Walcott,
and the more recent one of Lochman (1956) has given a fairly com-
plete description of the Early Cambrian fauna of this area, even
though the existence of Early Cambrian faunules not referable to
the Elliptocephala asaphoides assemblage had not been recognized
(Theokritoff, 1964; Rasetti and Theokritoff, 1967).

A paper on the stratigraphy of the Cambrian of Columbia County,
describing in detail the sections which supplied the fossils discussed
herein, will be published by Bird and Rasetti (in press).

The present work was supported by two grants (nos. 3454 and
4028) from the Penrose Fund of the American Philosophical Society,
and the writer gratefully acknowledges his indebtedness to the
Society. Thanks are also due to several persons who gave valuable
help in the course of the field work. Dr. John M. Bird, responsible
for the first finding of new Early Cambrian trilobites in Columbia
County, continued to cooperate enthusiastically in the discovery and
search of new fossiliferous localities and study of the stratigraphy,
and accompanied the writer in a number of field excursions. Dr.
Donald W. Fisher contributed his knowledge of the area and sug-
gested the examination of several potentially fossiliferous exposures,
some of which were productive. Dr. A. R. Palmer accompanied the
writer on a field excursion and collected valuable fossils. Dr. George
Theokritoff also contributed to collecting, and accompanied the writer
on an excursion in northern Washington County where he had thor-
oughly studied and mapped the rocks of the Taconic sequence. To all
these persons, and to Dr. E-An Zen, the writer is also indebted for
discussions on the stratigraphy and faunas.

OCCURRENCE OF THE FOSSILS

General statement.—The trilobites described herein, with a few
exceptions of specimens from other areas illustrated for comparison,
were collected by the writer, aided by the persons mentioned in the
acknowledgments, in a limited portion of Columbia County, New
York, chiefly either in the East Chatham 74-minute quadrangle
(Kinderhook 15-minute quadrangle) or the Hudson North 7%-
minute quadrangle (Coxsackie 15-minute quadrangle).

Almost all the material, excepting a few Lower Cambrian trilobites
of the Elliiptocephala asaphoides assemblage from shale deposits at
Judson Point, was recovered from more or less pure limestone beds or
lenses (only in exceptional cases from conglomerate boulders). The
specimens are seldom flattened or distorted, and in general preserve

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 3

the test and exhibit the aspect of the outer surface. Further details on
the manner of preservation are mentioned in the discussion of the
various localities.

Most of the fossils were collected from outcrops, usually in meas-
ured sections, hence in several cases the relative stratigraphic posi-
tion of various faunules could be established. Some of the specimens
illustrated herein, which were recovered from loose limestone blocks
in stone walls, belong to faunules that are also known from bedded
rocks.

Localities, as in the previous paper (Rasetti, 1966a) are designated
by the letters cs, followed by a locality number. A list indicating the
topographic position of each locality, determined by coordinates on
the U. S. Geological Survey maps, is given hereafter. When a collec-
tion is from a loose block in a stone wall on or near the Griswold farm
(the only area where collections from loose blocks were made), it is
labeled by the letters cs followed by the locality number (which may
be that of a nearby outcrop, if any), and the letter L or M, to indi-
cate a Lower or Middle Cambrian boulder, respectively, followed by
a boulder number.

An asterisk preceding the name in fossil lists indicates the type
locality for the species.

For brevity, author’s names are not indicated, since all the listed
species are described either in the present paper or the previous one
(Rasetti, 1966a).

When the collection is sufficiently large, an indication of the fre-
quency of species is given by the symbols (rr), very rare, (r), rare,
and (c), common. These indications are purely relative ; e.g., a spe-
cies indicated as common may be very rare in an absolute sense, only
less so than another designated as rare in the same collection.

East Chatham quadrangle: Griswold farm.—The area is located on
a hill about one mile SE. of North Chatham, Columbia County, on the
property of Mr. Grafton Griswold, and it supplied a great number of
trilobites, belonging to several Lower and Middle Cambrian faunules,
both from outcrops and loose blocks. This is the area where unusual
Cambrian fossils were first discovered in Columbia County in 1963.

A new Lower Cambrian faunule, chiefly characterized by an excep-
tionally large number of eodiscid trilobites, was already described
(Rasetti, 1966a) from one bed exposed on the Griswold farm (collec-
tion cs-4), and conjectures were advanced concerning the relationship
of the fossil bed to nearby outcrops. After that paper was written, a
trench deep enough to expose bedrock was excavated eastward from

4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

the fossil locality, revealing a sequence of black shales with several
interstratified limestone intervals, some of which did not appear on
the surface. All the strata show a uniform dip of 55° E. and unques-
tionably represent a sedimentary sequence. The trench was not
extended further in either direction, since surface exposures indicate
that only green and black shales would have been encountered west-
ward and eastward, respectively, for considerable distances. Fossil
evidence obtained by comparison with another section (Malden Bridge
road cut) indicates that the strata are not inverted; i.e., higher beds
are exposed eastward. A lens of intraformational limestone conglom-
erate in green shale is exposed 20 feet stratigraphically below the
lowest limestone listed below. The coarsely granular, light-gray matrix
holds good specimens of Salterella, but no other, more diagnostic,
fossils could be obtained.

The trilobites collected from the limestone beds exposed in the
trench are the following:

Collection cs-5 (USGS coll. 4215), 58 feet above base:
Olenellid fragments
Pagetides elegans
Pagetides rupestris
Peronopsis, sp. undet.
Prozacanthoides, sp. undet.

Collection cs-4c, 55 feet above base:

Pagetides elegans
Pagetides rupestris

Collection cs-4b, 53 feet above base:

Pagetides amplifrons
Pagetides elegans
Pagetides minutus
Prozacanthoides, sp. undet.
Collection cs-4a, 40 feet above base:
Bonnia, sp. undet.
Neopagetina taconica
Olenellid fragments
Pagetides minutus
Peronopsis, sp. undet.
Ptychopariacea, cranidium no. 1

Collection cs-4 at base (USGS coll. 4216; Acimetopus bilobatus
bed) :
* Acidiscus birdi
* Acidiscus hexacanthus
* Acimetopus bilobatus
* Analox bipunctata
* Bathydiscus dolichometopus

Ls Jel ll ¢ Jee: Ha J

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 5

* Bolboparia superba r
* Bolboparia elongata r
Bonnia, sp. no. 1 r
Bonnia, sp. no. 2 r
Bonnia, sp. no. 3 r
Bonnia, sp. no. 4 3
* Calodiscus fissifrons r

* Calodiscus occipitalis Ir
* Calodiscus reticulatus ie
Eodiscidae, pygidium no, 2 “on
Eodiscidae, pygidium no. 3 tr
Kootenia, sp. undet. rr
* Leptochilodiscus punctulatus r
* Litometopus longispinus r
Olenellus, sp. no. 1 ro
* Oodiscus binodosus Ir
* Oodiscus longifrons r
* Oodiscus subgranulatus r
Paedeumias, sp. no. 1
Paedeumias, sp. no. 2 r
* Serrodiscus griswoldi rr
* Serrodiscus latus rr
* Serrodiscus spinulosus r
* Serrodiscus subclavatus
Serrodiscus, sp. undet. rr
* Stigmadiscus gibbosus r
* Stigmadiscus stenometopus r

All the species from collection cs-4 were described by Rasetti
(1966a) except Serrodiscus griswoldi, which is described herein,
(p. 52).

Several other outcrops on the Griswold farm yielded a few fossils
of the Pagetides fauna, showing approximate equivalence to collec-
tions cs-4b and cs-5 listed above. In the wooded area just north of
the Griswold farm are several isolated outcrops, some of which pro-
duced a few, very fragmentary fossils. Only one collection is worth
listing.

Collection cs-15:

Pagetia bigranulosa
Pagetides minutus

An important exposure was found in the densely forested area W.
of the Griswold farm, S. of a pond not marked on the USGS quad-
rangle. Limestone beds, partly fine-grained, partly granular with
many small pebbles and fossil fragments, form outcrops at this locality
and produced an interesting Pagetides faunule including two repre-
sentatives of the family Eodiscidae.

6 SMITHSONIAN MISCELLANEOUS

Collection

cs-29:

Bonnia, sp. undet.
Eodiscidae, cephalon no, 3
Leptochilodiscus punctulatus
Pagetia bigranulosa
Pagetia laevis

Pagetides amplifrons
Pagetides elegans
Pagetides minutus
Peronopsis, sp. undet.

COLLECTIONS

" a}
Hoan aad sa

VOL. 152

Numerous blocks holding Lower Cambrian fossils, in all but one
case (cs-15/L3) belonging to the Pagetides fauna, were collected
from the stone walls on or north and west of the Griswold farm. In
all cases outcrops of the same age were located in the immediate
vicinity. However, in several cases the loose blocks produced more
numerous or better preserved examples of some of the trilobite spe-
cies. The species from those blocks that supplied illustrated specimens
are listed hereafter.

Collection

Collection

cs-3/L1:
Pagetides elegans
Pagetides rupestris

Corynexochacea, pygidium no, 4

cs-3/L2:
Acidiscus? sp. undet.

* Analox obtusa

Collection

Collection

Bonnia, sp. undet.
Olenellid fragments
Oodiscus, sp. undet.
Pagetia bigranulosa
Pagetides elegans
Pagetides leiopygus
Pagetides minutus
Pagetides rupestris
Protypus, sp. undet.
Prozacanthoides, sp. undet.
cs-3/L3:

Analox obtusa

Eodiscidae, pygidium no. 5
Pagetia bigranulosa
Pagetides elegans
Pagetides minutus
Pagetides rupestris

cs-15/L1:
Calodiscus, sp. undet.

Conocoryphidae, cranidium no. 1

ey

ann

rr
rr

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 7

Dorypygidae, cranidium no. 1
Olenellid fragments

Pagetides amplifrons

Pagetides elegans

Pagetides rupestris
Prozacanthoides, sp. undet.
Ptychopariacea, cranidium no, 1

Collection cs-15/L2:

Bonnia, sp. undet.
Olenellus, sp. no. 2
Paedeumias, sp. no. 5
Pagetides elegans

Collection cs-15/L3:

Analox bipunctata
Olenellus, sp. no. 1
Paedewmias, sp. no. 1
Paedeumias, sp. no. 2
Paedeumias, sp. no. 4
Paedeumias, sp. no. 6
Collection cs-15/L4:

Bolboparia, sp. no, 2 rr
Bonnia? sp. undet.

Neopagetina taconica r
Oodiscus, sp. undet. Ir
Pagetides minutus c

Collection cs-15/L5:

A mt » ym Ans

a) Ete ta.

Olenellus, sp. no, 2 r
Olenellus, sp. no. 3 r
Paedeumias, sp. no. 5 r
Pagetides elegans c
Pagetides rupestris r
Peronopsis, sp. undet, rr

Collection cs-17/L1:

Eodiscidae, pygidium no. 6 rr
* Pagetia bigranulosa c
Pagetides, sp. undet. r
Prozacanthoides, sp. undet. S
Serrodiscus spinulosus r

One outcrop on the Griswold farm yielded Middle Cambrian trilo-
bites of the Bathyuriscus-Elrathina zone.

Collection cs-6:

Elrathina, sp. undet. r

Peronopsis, sp. no. 3 r
* Pagetia clytioides

Oryctocephalus, sp. undet. rr

8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Faunules approximately of the same age were also recovered from
loose blocks in stone walls. The lists from the following boulders give
the associations observed.

Collections cs-7/M1 and cs-8/M1:
Meneviella, sp. undet.

Peronopsis, sp. undet. rz
Ptychagnostus gibbus c
Collections cs-7/M3, cs-7/M4, and cs-7/M5:
Bathyuriscus, sp. undet. tr
Ogygopsis? sp. undet. tr
* Pagetia erratica c
Peronopsis, sp. undet. r
Zacanthoides, sp. undet. rr

East Chatham quadrangle: Malden Bridge road cut.—Excellent
exposures occur in a deep road cut on Columbia County Route 32,
about one mile W. of Malden Bridge (Bird and Rasetti, in press). In
the eastern part of the cut, a few medium-gray, granular, 1-3 inches
thick limestone beds yielded a rather large Lower Cambrian faunule
(coll. cs-9a) very similar to the Acimetopus bilobatus faunule from
the Griswold farm. The strata holding this faunule are hereafter
referred to as the Leptochilodiscus beds. Fossils were first collected
here by J. M. Bird, A. R. Palmer, G. Theokritoff, and the writer in
March 1965. In addition to the fossils exposed in breaking the rock,
etching with hydrochloric acid produced rare silicified trilobites, some
belonging to species not otherwise observed. The trilobite tests are
replaced by a spongy, brittle, siliceous layer, and are often incrusted
with sand grains and other deposits that cannot be removed without
destroying the specimen. Several of the species from these beds are
known from one or very few individuals, an almost certain indication
that the faunule included more species than have been found. The
trilobites are listed below.

Collection cs-9a (Leptochilodiscus punctulatus beds) :

Acidiscus birdi ¢
Acimetopus bilobatus fr
Analox bipunctata a:
Bathydiscus dolichometopus rr
Bolboparia, sp. no. 1 rr

Bonnia, sp. undet.
Calodiscus lobatus

Calodiscus theokrito ffi rr
* Chelediscus chathamensis rr
Eodiscidae, cephalon no. 1 rr
Eodiscidae, cephalon no. 2 rr

Eodiscidae, cephalon no. 4 Ir

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 9

Eodiscidae, pygidium no. 7 rr
Leptochilodiscus punctulatus c
Olenellus, sp. no. 2 3
Oodiscus, sp. no. 1 rr
Paedeumias, sp. no. 1

Paedeumias, sp. no. 2 r
Paedeumias, sp. no. 3 Ir
Serrodiscus latus ps
Serrodiscus spinulosus c
Stigmadiscus stenometopus Ir

Farther W. in the road cut, on the N. side, 32 feet higher strati-
graphically than the Leptochilodiscus beds, another limestone interval
yielded a Neopagetina faunule, including the following trilobites.

Collection cs-9:

* Neopagetina taconica g
Pagetides minutus tr
Peronopsis, sp. no. 5 Ir
Ptychopariacea, cranidium no. 1 rr

West of this interval, the beds are so folded and faulted that their
sequence cannot be ascertained ; presumably a considerable shale inter-
val was faulted out. Dark gray, partly laminated limestone beds
exposed on both sides of the road cut, 80 feet W. of the Neopagetina
beds (the strata being almost vertical), yielded a Middle Cambrian
faunule characterized by Ptychagnostus gibbus and other trilobites of
the Bathyuriscus-Elrathina zone (coll. cs-9c, cs-9c’ on N. side, coll.
cs-9d, cs-9d* on S. side of cut). Even though all these collections
were recovered within a 2-foot interval, they are listed separately, as
the associations varied even between adjacent beds. The faunules from
this locality are listed below.

Collection cs-9c

Pagetia clytioides r
Collection cs-9c’ :
Ptychagnostus gibbus c

Collection cs-9d :

Bathyuriscus, sp. undet.
Peronopsis, sp. no. 1
Peronopsis, sp. no. 2
Ptychagnostus gibbus
Collection cs-9d *, from adjacent bed above cs-9d:
Bathyuriscus, sp. undet.
Kootenia, sp. no. 1

Meneviella, sp. undet.
Peronopsis, sp. no. 1

aoaan

anan

Io SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

East Chatham quadrangle: other localities—Trilobites of the
Lower Cambrian Pagetides fauna were collected from about a dozen
outcrops of bedded limestone in the NW. quarter of the East Chatham
quadrangle, in addition to the Griswold Farm and Malden Bridge
road cut localities previously discussed. In the same area, a few
conglomerate exposures yield pebbles with the Elliptocephala asa-
phoides fauna.

Two outcrops located on the Lopez farm, east of the Nassau-
Malden Bridge road, yielded interesting Pagetides faunules. Both
show approximately vertical beds trending north-south, and the field
evidence is inadequate to determine their stratigraphic order. How-
ever, comparison of the faunules with those collected from the meas-
ured section on the Griswold farm leaves little doubt that the collec-
tion cs-20 is from older beds than the collection cs-18. The trilobites
from these collections are listed below.

Collection cs-20, Lopez farm:

Neopagetina taconica c
Pagetides minutus c
Peronopsis, sp. undet. tr

This faunule seems to be a precise equivalent of those occurring at
localities cs-4a on the Griswold farm and cs-9 at the Malden Bridge
road cut.

Collection cs-18, Lopez farm:

Bonmia, sp. undet. r
Calodiscus lobatus rr
Olenellidae, undet. fragments r
Oodiscus, sp. undet. tr
Pagetides elegans r
Pagetides minutus c
Peronopsis, sp. undet. tr

Fossiliferous localities are much scarcer in the NE. quarter of the
East Chatham quadrangle, E. of the “Chatham thrust” (Craddock,
1957), and the two known to the writer yielded exclusively Lower
Cambrian fossils. :

Fossiliferous limestone beds are rather extensively exposed on the
W. slope of a wooded ridge about one mile SE. of Riders Mills and
one mile S. of Ashley Hill. Dale (1904, p. 24) and Craddock (1957,
p. 695) discussed the age of the limestone at this locality ; both men-
tion conglomerate beds that the writer was unable to find. Trilobites
collected from a blue-gray, bedded limestone are listed below.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI II

Collection cs-26:

Bonnia, sp. undet. 4
Calodiscus walcotti r
Kootenia, sp. no. 2 rr
* Pagetia laevis c
Pagetides elegans r
Pagetides minutus Cc
Prozacanthoides, sp. undet. r

This is a typical Pagetides faunule, unusual only in the presence of
Calodiscus walcotit.

The other Cambrian fossiliferous locality in the NE. quarter of the
East Chatham quadrangle is the classic exposure of limestone con-
glomerate at Ashley Hill, discussed by Dale (1904), Lochman (1956),
and Craddock (1957). The conglomerate is associated with massive
quartzite, a relationship not observed at the numerous conglomerate
exposures in the Troy area, at Schodack Landing, and in the NW.
quarter of the East Chatham quadrangle. In other respects, particu-
larly the lithology of the pebbles and boulders, all these conglomerates
are quite similar. Some of the boulders at Ashley Hill are the usual
coquina of Elliptocephala asaphoides fragments, and occasionally yield
well-preserved examples of the smaller trilobites, in addition to many
fossils of other phyla. Lochman (1956) listed the species from the
boulders in the Ashley Hill Conglomerate. The writer, in addition to
previously listed species, collected good examples of Rimouskia typica,
a trilobite hitherto unknown from the Taconic sequence (coll. cs-19).

Hudson North quadrangle: Stockport Station—An_ excellent
exposure of 9 feet of sandy, medium-bedded limestone under-
lain and overlain by thick-bedded sandstones occurs near the New
York Central Railroad tracks at the site of the former Stockport Sta-
tion. Fossils were discovered at this locality by J. M. Bird and D. W.
Fisher in April 1965, and are confined to one limestone bed with a
much lesser sand content than any other. Over 1,000 pounds of rock
from this bed were quarried and examined for the minute trilobite
fragments. Usually, only specimens not exceeding a millimeter in
length have been preserved without excessive breakage; occasionally
cranidia, free cheeks, and pygidia of larger sizes can be recovered.
The trilobites described and figured herein are listed below.

Collection cs-21, Stockport Station:

Athabaskiella, sp. undet. r
* Baltagnostus stockportensis
* Bathyuriscus eboracensis

Bathyuriscidella, sp. undet. rr

an

I2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

* Bolaspidella fisheri c
Corynexochacea, pygidium no. 1 rr

* Corynexochides? expansus c
Elrathia? sp. undet.
Hemirhodon, sp. undet. r
Hypagnostus parvifrons r

* Olenoides stockportensis rr
Olenoides, sp. undet. r
Leiopyge? sp. no. 1 rr
Leiopyge? sp. no. 2 rr
Peronopsis, sp. no. 4 tr
Ptychagnostus punctuosus iis
Ptychagnostus, sp. undet. r
Ptychopariacea, cranidium no. 2 Gi
Ptychopariacea, cranidium no. 3 rr
Ptychopariacea, cranidium no. 4 Ir
Ptychopariacea, pygidium no. 1 tr

This bed supplied also many different forms of immature (protaspid
and meraspid) stages, probably representing a number of additional
genera and species. These were not described or figured since there
seemed to be no point in describing ontogenetic stages not referable
to adult forms. Similar remarks apply to the faunules of the next two
localities to be discussed, Judson Point and Nutten Hook.

In addition to the trilobites, excellent shells of Pegmatreta cf.
ophirensis (Walcott) were recovered by etching samples of rock with
formic acid (Palmer, private communication). The brachiopod is
important as it establishes a relation with the faunule of locality cs-22
where the trilobites are less indicative of a precise age.

The above faunule is clearly of very late Middle Cambrian age and
has many elements in common with both the Bolaspidella zone faunas
of western Utah described by Robison (1964a) and the uppermost
zone of the Paradoxides paradoxissimus stage in Scandinavia.

Hudson North quadrangle: Judson Point—A continuously ex-
posed section of about 250 feet of strata in conformable sedimentary
sequence occurs along the New York Central Railroad tracks on the
E. shore of the Hudson River at Judson Point. Goldring (1943, fig.
11) reproduced a photograph of part of the strata, referred to the
Lower Cambrian Nassau beds of Ruedemann (1942). All the strata
dip uniformly 40° E. and seemingly about 130 feet of exposed black
shale overlie 120 feet of alternating sandstones, shales, sandy or rela-
tively pure limestones, and limestone conglomerates. However, the
fossil evidence (Bird and Rasetti, in press) unquestionably shows that
the strata are overturned, the black shale underlying the sandstone-
shale-limestone sequence. Fossils at Judson Point were first collected

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 13

by D. W. Fisher about 40 feet below the top of the shale, and indicate
the Lower Cambrian Elliptocephala asaphoides fauna. Additional
fossils in this interval were collected by H. B. Whittington, J. M. Bird,
and the writter (collections cs-24, cs-24b, respectively, 30-40 and 75
feet below the top of the shale). The same species of trilobites occur
throughout this interval and are listed below.

Collections cs-24, cs-24b, Judson Point :

Atops trilineatus
Elliptocephala asaphoides
Rimouskia typica
Serrodiscus speciosus

Elliptocephala is represented by fragments of large individuals,
recognizable by the characteristic ornamentation. Serrodiscus spe-
ciosus is particularly common in an interval of green shale (coll. cs-
24b), where excellent articulated specimens were found.

Fossils also occur in a 2-5-inch bed of sandy, partly tan-weather-
ing limestone 52 feet above the top of the black shale. The trilobites,
mostly of diminutive size, are generally comminuted and unrecogniza-
ble. However, by careful search through hundreds of pounds of rock,
small but at least in part identifiable specimens were recovered. The
following list includes only the species that were deemed well enough
represented to be worth describing and figuring.

Collection cs-23, Judson Point (Centropleura bed) :
Agnostida, pygidium no. 1
Agnostida, pygidium no. 2
Baltagnostus, sp. undet.
Bathyuriscus eboracensis
Centropleura, sp. undet.
Corynexochacea, pygidium no. 2
Corynexochacea, pygidium no. 3
Corynexochides? expansus
Grandagnostus? sp. undet.
Hypagnostus parvifrons
Ptychopariacea, cranidum no. 8
Ptychopariacea, pygidium no. 2

The faunule is unquestionably of late Middle Cambrian age, prov-
ing that the section is inverted. In addition to the trilobites, the same
Pegmatreta occurring at Stockport Station and Nutten Hook was
etched from this bed.

Hudson North quadrangle: Nutten Hook.—A sequence of shales,

14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

sandy or pure, aphanitic, thin-bedded limestones, underlain by thick-
bedded sandstone, is exposed at the N. end of the S. hill of Nutten
Hook, a rocky promontory on the E. shore of the Hudson River. Gold-
ring (1943, p. 75, figs. 16, 17) described and figured this section,
referring all the strata to the Lower Cambrian. A more detailed de-
scription is given by Bird and Rasetti (in press). A sandy limestone
bed was found to contain very small and fragmentary trilobites,
besides a well-preserved, inarticulate brachiopod. Specimens of the
latter, etched and identified by Palmer (private communication),
appear identical with the species of Pegmatreta recovered from the
Stockport Station bed. The trilobites are listed below.

Collection cs-22, Nutten Hook:

Agnostida, pygidium no, 1

* Baltagnostus angustilobus
Goniagnostus, sp. undet.
Hypagnostus parvifrons
Hypagnostus, sp. undet.
Ptychopariacea, cranidium no. 5
Ptychopariacea, cranidium no. 6
Ptychopariacea, cranidum no, 7
Ptychopariacea, pygidium no, 3
Ptychopariacea, pygidium no, 4
Ptychopariacea, pygidium no. 5

The cranidia no. 5 and no. 7 and the pygidium no. 4 are suggestive
of early Upper Cambrian forms. However, the presence of Goniag-
nostus and Hypagnostus is definitely indicative of the uppermost Mid-
dle Cambrian Bolaspidella zone like the beds at Stockport Station and
Judson Point.

INDEX OF LOCALITIES

Localities where the collections were made are here specified by
coordinates on the U. S. Geological Survey 714-minute quadrangles,
scale 1:24,000. In the absence of contrary indication, the abscissa is
measured from the west edge, the ordinate from the south edge of the
map. A minus sign in front of the value of the coordinate means that
it was measured from the opposite edge (east edge for the abscissa,
north edge for the ordinate). This practice was followed in order to
refer a location to the nearer margin of the map, thus minimizing
errors due to variation of the map size with humidity.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 15

Locality USGS Abscissa Ordinate

Symbol Quadrangle (mm.) (mm.) Description
tats ks a ie East Chatham 29 —185 Griswold farm (loose blocks)
es-4 fo cs-5 .... * os 27-28 —165 Griswold farm
See es _ 2 35 —160 Griswold farm
Ge Hewett a *. ¢ 27-35 —158 Griswold farm (loose blocks)
re ee ee x: S 28-32 —172 Griswold farm (loose blocks)
cs-9 tocs-9d ... “ ; 84-86 —148 Malden Bridge road cut
aR A 4 34 —150 N. of Griswold farm
Weer nev aveias « " = 16 —164 W.of Griswold farm
SHS Vitec t sb 115 —91 Lopez farm
popes Se “ x 269 —72 Ashley Hill
rj a i . 115 —88 Lopez farm
Ce 3 * 261 —129 Riders Mills
i zi 8 19 —176 W. of Griswold farm
OUR cap eh anne s Hudson North —77 281 Stockport Station
Be Cais ctivs . * —135 —83 Nutten Hook
r Y ¢ Geke pAo 4 —86 —246 Judson Point
cs-24, cs-24b ... be —85 —244 Judson Point

BIOSTRATIGRAPHY

LOWER CAMBRIAN

Elliptocephala fauna.—The oldest Early Cambrian fauna in the
Taconic sequence is believed to be the Elliptocephala asaphoides
assemblage. This fauna is known from Columbia and Rensselaer
Counties, where it occurs chiefly in conglomerate boulders, and from
Washington County, where it was generally recovered from lenticu-
lar, irregularly bedded limestone bodies in the Mettawee Slate and the
West Castleton Formation (Theokritoff, 1964), or exceptionally from
black shale. Even though the widespread occurrence of the fauna in
rocks of various lithologies suggests that the assemblage is rather
long-ranging in the Taconic sequence, it has not been possible to
establish the total stratigraphic range of the Elliptocephala fauna.

In the particular area studied in the present work, northern Colum-
bia County, the Elliptocephala fauna occurs in limestone conglomerate
boulders at Ashley Hill and several other localities in the East Chat-
ham quadrangle, in black or green shale in the Judson Point section,
where it ranges through at least 50 feet of beds, and south of Scho-
dack Landing. Bird and Rasetti (in press) restudied the Schodack
Landing section, showing that there are exposed in conformable suc-
cession at least 217 feet of beds, green shale prevailing in the lower
part, black shale and sandstone in the upper third, with limestone
present both as bedded rock and as conglomerate boulders in several

16 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

intervals. The Elliptocephala asaphoides fauna was found in lime-
stone 60-70 feet above the base of the exposed section. Ford (1884)
reported Serrodiscus speciosus from thin-bedded limestone about 45
feet higher in the section. In the still higher intervals, diagnostic fos-
sils were collected only from conglomerate pebbles. It is possible that
all the exposed strata fall within the range of the Elliptocephala asa-
phoides assemblage.

Lochman (1956) listed the fossils of the Elliptocephala fauna and
compared the composition of that assemblage with faunas from other
areas of North America and Europe. However, Rasetti and Theokri-
toff (1967) have shown that forms of the Pagetides fauna were
included, owing to misleading interpretation of some of the fossil lists
from Walcott’s localities. A list of the trilobites, probably not com-
plete but based exclusively on the writer’s first-hand evidence,
follows.

Elliptocephala asaphoides fauna

Atops trilineatus
Calodiscus lobatus
Calodiscus meeki
Elliptocephala asaphoides
Fordaspis nana
Hebediscus marginatus
Kootenia troyensis
Rimouskia typica
Serrodiscus speciosus

When only the genera and species of this restricted list are con-
sidered, the Elliptocephala assemblage appears closer to the European
Early Cambrian faunas and less related to the faunas of the Appala-
chian and Cordilleran provinces of North America than Lochman had
deduced from her more extensive list. Cobbold (1936) has shown that
Atops occurs in Comley, Shropshire, with Calodiscus lakei Rasetti
(1952), closely related to C. lobatus. Hebediscus is a typical Acado-
Baltic genus, known in North America from Newfoundland (Hutch-
inson, 1962) and Massachusetts. Elliptocephala and Fordaspis have
not been found outside the Taconic sequence, and Rimouskia has been
found only in association with unknown Olenellids in boulders in
Quebec. Serrodiscus speciosus, or extremely similar forms, are
known from various areas in Europe and Africa. R. and E. Richter
(1941) described Serrodiscus cf. speciosus from Andalusia, Spain,
and Silesia, Germany. Hupé (1952) described Serrodiscus coloi,
almost identical with S. speciosus, from the Anti-Atlas of Morocco.
Recent stratigraphic work has clearly established the position of the

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 17

Serrodiscus or Calodiscus beds in the Lower Cambrian sequence. In
Shropshire, according to Whittard (1952), the “Eodiscus limestone”
overlie the Callavia beds (but still includes representatives of that
Olenellid genus) and underlies the Protolenus and Strenuella lime-
stones. In Germany, according to Sdzuy (1960, 1961) the shales with
Serrodiscus underlie Protolenus shales. In Spain, the extensive work
of Lotze (1961, pp. 467-469) has established the most detailed zona-
tion of the Lower Cambrian so far obtained in Europe. Serrodiscus
cf. speciosus occurs above the strata characterized by members of the
family Dolerolenidae and just below those carrying Saukianda and
Perrector. These are immediately overlain by beds holding a number
of genera of the Protolenidae. An entirely analogous stratigraphic
position is occupied by Serrodiscus in Morocco (Hupé, 1952, p. 94),
where it occurs in the Termierella zone, in association also with
Kingaspis, Micmacca, Strenuella, and other genera.

We may thus tentatively correlate the strata holding the Ellipto-
cephala asaphoides assemblage in the Taconic sequence with the beds
carrying Serrodiscus speciosus or similar species in Europe and North
Africa, which also correlate closely with each other on the basis of
other trilobite families. There is, however, little similarity between
the Elliptocephala fauna and the faunas of Europe and North Africa
aside from the Eodiscidae and the Pagetiidae. In particular, the Pro-
tolenidae and Ellipsocephalidae, which play a dominant role in those
faunas, are totally absent from the Taconic sequence.

When some of the species listed by Lochman are excluded, there
remains only one genus of trilobites, Kootenia, common between the
Elliptocephala assemblage and the faunas of the Lower Cambrian of
the Appalachian and Cordilleran provinces, and furthermore, the only
ascertained species in the Elliptocephala fauna, Kootenia troyensis, is
quite different from any of the species known from Quebec, Vermont,
the southern Appalachians, and the western United States.

In conclusion, while the Elliptocephala asaphoides fauna has a
character of its own, substantially different from both the faunas of
“Atlantic” and “Pacific” facies, on the basis of some of the trilobites
it can be correlated much more closely with the former than the
latter.

The Elliptocephala assemblage, in addition to the trilobites and
several species of brachiopods, contains an unusually large number of
invertebrates belonging to miscellaneous, partly undetermined phyla.
These have been adequately described and illustrated by Lochman
(1956).

18 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Acimetopus fauna.—The next younger Early Cambrian fauna is
presumably the one discussed in the previous paper (Rasetti, 1966a)
and designated the Acimetopus bilobatus fauna. It is so far known in
the Taconic sequence only from two outcrops, cs-4 (Griswold farm)
and cs-9a (Malden Bridge road cut), both in the East Chatham quad-
rangle. The collection from loose block cs-15/L3 probably may be
included in the assemblage, since most of the species are common
either to collection cs-4 or cs-9a. Since the species from these three
collections were already listed in the discussion of localities, repetition
seems unnecessary. The fauna includes 24 named plus a few unnamed
species of Eodiscidae, in part belonging to new genera known exclu-
sively from the assemblage. The Olenellidae are represented by 3
species referred to Olenellus and 6 species referred to Paedeumuas, all
known exclusively from immature forms and hence not comparable
with species described from other formations and based on mature
individuals. The Agnostida and the Pagetiidae are totally absent. The
opisthoparian trilobites are represented by several, unnamed species of
Bonnia and one species of Kootenia. No ptychoparioid trilobites are
known from the assemblage.

Even though the Acimetopus bilobatus fauna seemingly has no trilo-
bite species in common with the Elliptocephala asaphoides fauna, the
representation of the various trilobite families is similar in the abun-
dance of individuals of Eodiscidae and Olenellidae, absence of Agnos-
tida and Pagetiidae, and near absence of Ptychopariacea. The chief
difference is that the families Olenellidae and Dorypygidae in the
Acimetopus fauna are mainly represented by the widespread genera
Olenellus, Paedeumias, and Bonnia, in the Elliptocephala fauna by the
endemic genera Elliptocephala and Fordaspis, respectively.

The evidence suggesting that the Acimetopus fauna is younger than
the Elliptocephala fauna is discussed by Bird and Rasetti (in press).
Both in the Griswold farm and Malden Bridge road cut sections, the
earliest faunule of the Pagetides fauna, the Neopagentina taconica
faunule, overlies about 30-35 feet stratigraphically the beds carrying
the Acimetopus fauna. Since the Elliptocephala fauna ranges through
a considerable thickness of beds, presumably several hundred feet, in
Washington and Columbia Counties (in the latter at Schodack Land-
ing and Judson Point) it appears quite unlikely that the time equiva-
lent of all the beds carrying the Elliptocephala fauna can be repre-
sented by a portion of those 30-35 feet of unfossiliferous shale. This
leads to the almost certain conclusion that the Elliptocephala asaphoi-
des fauna must be either older, or younger, than both the Acimetopus

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 19

and Pagetides faunas. The presence of the Elliptocephala fauna in
numerous conglomerate outcrops, both in the East Chatham quad-
rangle and elsewhere, which certainly occupy a lower stratigraphic
position than the Pagetides beds, definitely indicates that the Ellipto-
cephala fauna is the oldest of the three here discussed.

The Acimetopus fauna, in addition to the trilobites, contains a few
inarticulate brachiopods. Other phyla are only represented by rare
specimens of Hyolithellus.

In the previous paper (Rasetti, 1966a, p. 21) it was pointed out that
the discovery of Bolboparia canadensis, closely related to one of the
Eodiscidae in the Acimetopus bilobatus fauna, in Lower Cambrian
strata near Elgin Station, L’Islet County, Quebec (about 40 miles NE
of Levis, Quebec), seemingly indicated the presence of an equivalent
fauna outside of the Taconic sequence. This conclusion is fully con-
firmed by the finding, through a search at that locality by G. Theokri-
toff, of two species of the Acimetopus fauna known from the Colum-
bia County localities, Calodiscus theokritoffi and Leptochilodiscus
punctulatus. Unfortunately these fossils occur at the Canadian locality
in an isolated outcrop and therefore cannot be related to other Lower
Cambrian faunas known from Quebec.

Pagetides fauna.—The third and youngest Early Cambrian fauna
known from the Taconic sequence was named (Rasetti, 1966a) the
Pagetides fauna from the frequent occurrence of species of that
genus. It is widespread in northern Columbia County and is repre-
sented in Washington County by the Pagetia connexa faunule
(Rasetti and Theokritoff, 1967), known from several localities and
previously confused with the Elliptocephala asaphoides fauna. Pagetia
connexa has not been found in Columbia County, even though other
Lower Cambrian species of the genus are relatively common, but the
presence of common species in the Pagetia connexa faunule of Wash-
ington County and the Pagetides faunules of Columbia County
indicates that we are dealing with essentially contemporaneous
assemblages.

In the Pagetides fauna of Columbia County it seems appropriate to
distinguish an earliest faunule which shall be designated the Neo-
pagetina taconica faunule (coll. cs-4a, cs-9, and cs-20 in place, loose
block cs-15/L4) and includes the following species:

Neopagetina taconica faunule
Bolboparia, sp. no, 2
Bonnia, sp. undet.
Neopagetina taconica
Oodiscus, sp. undet.

20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Pagetides minutus

Peronopsis, sp. no. 5
Ptychopariacea, cranidium no, 1
Undetermined Olenellidae

The other, presumably younger collections of the Pagetides fauna
cannot be placed in stratigraphic order, and since they have many
species in common, are united into a single faunule, characterized by
Pagetides elegans and including the following species of trilobites:

Pagetides elegans faunule

Acidiscus? sp. undet.

Analox obtusa

Bolboparia, sp. no. 2

Bonnia, sp. undet.

Calodiscus lobatus
Calodiscus walcotti
Calodiscus, sp. undet.
Conocoryphidae, cranidium no, 1
Dorypygidae, cranidium no, 1
Eodiscidae, cephalon no. 3
Eodiscidae, pygidium no. 5
Eodiscidae, pygidium no. 6
Kootenia, sp. no. 2
Leptochilodiscus punctulatus
Olenellus, sp. no, 2

Olenellus, sp. no. 3

Oodiscus, sp. undet.
Paedeumias, sp. no. 5
Pagetia bigranulosa

Pagetia laevis

Pagetides amplifrons
Pagetides elegans

Pagetides leiopygus
Pagetides minutus

Pagetides rupestris
Peronopsis, sp. undet.
Protypus, sp. undet.
Prozacanthoides, sp. undet.
Ptychopariacea, cranidium no. 1
Serrodiscus spinulosus

The character of the faunule depends not only on the genera and
species present but also on the number of individuals representing
them. The Pagetiidae (Pagetia, Pagetides) are by far the most
common trilobites. Olenellid fragments are relatively abundant but
seldom identifiable ; Bonnia and Prozacanthoides are moderately fre-
quent. All the other trilobites, i.e., the few Ptychopariacea, the Eodis-

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 2I

cidae, and the Agnostida (Peronopsis), are excessively rare, many of
the genera and species being represented in the collections by a single
fragment. Of particular interest are the genera and species common
to the underlying Acimetopus fauna. These are the genera of Eodisci-
dae, Acidiscus, Analox, Bolbaparia, Calodiscus, Leptochilodiscus, and
Serrodiscus, and among the other families Bonnia, Kootenia, Olenel-
lus, and Paedeumias. The only species in common that have been
identified are Olenellus sp. no. 2, Leptochilodiscus punctulatus, and
Serrodiscus spinulosus. There is only one species, Calodiscus lobatus,
common to the Pagetides and Elliptocephala faunas ; it is represented
by a single cephalon in collection cs-18.

Outside of the Taconic sequence, faunules where Pagetides is com-
mon are known from one outcrop of bedded limestone and numerous
conglomerate boulders in Quebec (Rasetti, 1945, 1948a, 1955). In the
“Austinvillia’ bed (correctly Bicella bed), Pagetides amplifrons and
P. pustulosus are associated with Bonnia sp. and the Ptychoparioids
Bicella bicensis and Periomma punctata. In the boulders, Pagetides
amplifrons, P. elegans, P. leiopygus, P. minutus, and P. rupestris, all
species occurring in the Pagetides fauna of Columbia County, are
associated with species of Olenellidae, Bonnia, Kootenia, Prozacan-
thoides and the Ptychopariacea Bicella, Periomma, and Periommella.
The presence of several species of Pagetides and genera of Corynexo-
chacea common to this fauna from Quebec and the Pagetides fauna in
Columbia County is almost certain indication of approximately equiva-
lent age. The chief differences between the two faunas are the total
absence of the Eodiscidae from the Quebec fauna and the near absence
of Ptychopariacea from the Columbia County fauna. In this respect,
the Pagetides fauna of the Taconic sequence has less in common with
the typical, late Early Cambrian faunas of the Appalachian and Cor-
dilleran provinces and shows some relationship with the faunas of the
Acado-Baltic province of North America and Europe, where the
Eodiscidae are well represented. However, in the Pagetides fauna the
Acado-Baltic character is less pronounced than in the Elliptocephala
asaphoides and Acimetopus bilobatus faunas, where the Eodiscidae
predominate.

Species of Pagetides are also known from the Olenellus shales of
the Appalachian province, as Pagetides elegans occurs (Rasetti,
1948a) in the Parker Shale at the Kelly quarry near Swanton Junc-
tion, Vermont, and the generically, but not specifically, identifiable
Pagetides parkeri (Walcott) was described from the same formation
at the classic locality near Georgia, Vermont (Rasetti, 1952, p. 439).

22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Undescribed, poorly preserved specimens of Pagetides from the
Kinzers Shale of the Lancaster, Pennsylvania basin are preserved
in the U. S. National Museum. It is therefore plausible to assume that
the Pagetides fauna of Columbia County is approximately contem-
poraneous with the typical Olenellus fauna described by Resser and
Howell (1938), the prevalence of Olenellidae in the latter being prob-
ably determined by the shaly character of the deposits.

In New York State the Pagetides fauna has never been observed in
conglomerate boulders, in contrast to the most frequent mode of occur-
rence of the Elliptocephala fauna.

MIDDLE CAMBRIAN

Discovery of Middle Cambrian faunas in the Taconic sequence.—It
has been a widely held opinion of stratigraphers that the Taconic
sequence does not include strata of Middle Cambrian age, owing to
non-deposition or erosion during that epoch, and possibly part or all
of the Late Cambrian. Such conditions may well obtain in the northern
part of the Taconic region, in Washington County, where graptolite-
bearing, Early Ordovician shales seemingly overlie directly the black
shales of the West Castleton Formation (Theokritoff, 1964) or are
separated by a thin interval of the Hatch Hill Formation, believed of
Late Cambrian age. Lochman (1956, p. 1366) reported and figured
(pl. 5, figs, 22, 23) a fragmentary cephalon referred to Eodiscus
punctatus, a characteristic trilobite of the Middle Cambrian of the
Acado-Baltic province, collected from a loose boulder in the Cam-
bridge quadrangle, Washington County. The writer does not con-
sider the specimen complete enough to warrant positive identification,
especially in view of the discovery of Lower Cambrian Eodiscidae
with a similarly punctate surface. The other, supposedly Middle
Cambrian trilobite cited by Lochman, Mallagnostus desideratus (Wal-
cott) was shown (Rasetti and Theokritoff, 1967) to belong to the
Eodiscidae and to be a member of the Early Cambrian Pagetia con-
nexa faunule.

Unquestionable Middle Cambrian trilobites were first discovered in
the Taconic sequence of Columbia County by J. M. Bird and the
writer in the fall of 1963. The fossils, among which the most common
species was Ptychagnostus gibbus, were at that time recovered only
from loose blocks on the Griswold farm. Subsequently an outcrop
yielding trilobites approximately of the same age (collection cs-6)
was discovered in the same area. More numerous trilobites of the
Bathyuriscus-Elrathina zone were found by the writer in 1965 in the

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 23

Malden Bridge road cut. In the same year fossiliferous beds of the
latest Medial Cambrian Bolaspidella zone were discovered in the sec-
tions along the bluffs on the east shore of the Hudson River, at Stock-
port Station, Judson Point, and Nutten Hook, in the Hudson North
quadrangle.

Fauna of the Bathyuriscus-Elrathina zone—The oldest Middle
Cambrian fossils known from Columbia County, and the Taconic
sequence in general, belong to the Bathyuriscus-Elrathina zone. At
least provisionally 3 faunules may be separated, two collected from
outcrops at different localities, the third known exclusively from loose
boulders ; therefore their time order is unknown, but age differences
are probably small.

The first faunule (collections cs-9c, cs-9c’, cs-9d, cs-9d*) occurs
within a narrow stratigraphic interval in the Malden Bridge road cut
section, and is represented by the identical species in loose blocks on
the Griswold farm (collections cs-7/MI, cs-8/MI). The trilobites of
this Ptychagnostus gibbus faunule include the following species:

Ptychagnostus gibbus faunule
Bathyuriscus, sp. undet.
Kootenia, sp. no. 1
Meneviella, sp. undet.
Pagetia clytioides
Peronopsis, sp. no. 1
Peronopsis, sp. no. 2
Ptychagnostus gibbus

The second faunule occurs in an isolated outcrop on the Griswold
farm (collection cs-6) and is designated by the trilobite Pagetia
clytioides.

Pagetia clytioides faunule

Elrathina? sp. undet.
Pagetia clytioides
Peronopsis, sp. no. 3
Oryctocephalus, sp. undet.

The third faunule of the Bathyuriscus-Elrathina zone was only
recovered from loose blocks (collections cs-7/M3, cs-7/M4, and cs-
7/MS5). It is designated by the trilobite Pagetia erratica and includes
the species :

Pagetia erratica faunule
Bathyuriscus, sp. undet.
Ogygopsis, sp. undet.
Pagetia erratica

Peronopsis, sp. undet.
Zacanthoides, sp. undet.

24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

These faunules are typical of the Bathyuriscus-Elrathina zone of
the Cordilleran province. They may be compared with the faunules
occurring at several levels in the Stephen Formation of British Colum-
bia (Rasetti, 1951). All the genera occur in the Stephen Formation,
except Meneviella, which is typical of the Acado-Baltic province.
The type and only described species, Meneviella venulosa, occurs in
Britain, and good material was recently figured by Hutchinson (1962)
from Newfoundland, where the species ranges from the uppermost
Paradoxides hicksi through the Paradoxides davidis stages. The
Ptychagnostus gibbus faunule, of which Meneviella is a member,
can be more accurately correlated with zone B1, the lowest of the
Paradoxides paradoxissimus stage of Sweden, since Ptychagnostus
gibbus is the guide fossil of that zone and is confined to it. The sug-
gested equivalence of the Piychagnostus gibbus beds in Sweden and
the Taconic sequence is in agreement with Robison’s (1964b) correla-
tion of the Middle Cambrian of Sweden and Utah, according to which
the Ptychagnostus gibbus zone corresponds to the upper part of the
Bathyuriscus-Elrathina zone.

For the other two faunules, designated by the species Pagetia
clytioides and Pagetia erratica, no direct correlation with faunas of
the Acado-Baltic province is possible, since all the species either belong
to western North American genera or to the long-ranging Agnostid
genus Peronopsis. The long stratigraphic range of the genera also
prevents more accurate correlation with faunules of the Cordilleran
province than reference to the Bathyuriscus-Elrathina zone.

Fauna of the Bolaspidella gzone—The other Middle Cambrian
faunules, found only in the Hudson North, quadrangle, belong to the
Bolaspidella zone, the latest Middle Cambrian faunizone of the Cordil-
leran province.

The best represented of these faunules is the one from Stockport
Station (collection cs-21). The list of trilobite species was given with
the description of that locality. The faunule will be designated by the
trilobite Bathyuriscus eboracensis, one of the most common of the
named species. Correlation with some portion of the Bolaspidella zone
is obvious as it is supported by a number of trilobite genera and the
presence of Pegmatreta cf. ophirensis. However, as suggested by
Robison (1964b), the Bolaspidella faunizone represents a long time
span, believed equivalent to all but the lowest, Ptychagnostus gibbus
zone of the Paradoxides paradoxissimus stage plus the entire Para-
doxides forchhammeri stage. A comparison of the Bathyuriscus
eboracensis faunule with the range of genera and species in the

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 25

Bolaspidella zone of western Utah suggests as most likely an equiva-
lence to the upper part of the lower, Bathyuriscus fimbriatus subzone
(Robison, 1964a, p. 512). This conclusion would also be in agreement
with the occurrence of Ptychagnostus punctuosus, which in Sweden is
the guide fossil of the uppermost zone (B4) of the Paradoxides
paradoxissimus stage (Westergard, 1946, pp. 98-103). The only
difficulty with the suggested correlation is the apparent presence in the
Bathyuriscus eboracensis faunule of representatives of the genus
Leiopyge, which in Utah is confined to the uppermost portion of the
upper, Bolaspidella contracta subzone of the Bolaspidella zone, and in
Sweden is only known from the two upper zones, C2 and C3, of the
Paradoxides forchhammeri stage. The evidence of all the other
species, however, makes it unlikely that the Bathyuriscus eboracensis
faunule is as young as suggested by the presence of Leiopyge. It is
possible that either Leiopyge appeared in the Taconic sequence earlier
than in Scandinavia and Utah, or, perhaps more likely, the smooth
Agnostid cephala have been misidentified as Leiopyge in the absence
of pygidia, and should instead be referred to some other genus.
Species referred by Westergard to Ciceragnostus and Phalacroma
already occur in the Paradoxides paradoxissimus stage.

The second faunule of late Middle Cambrian age occurs in a sandy
limestone bed at Judson Point (coll. cs-23) and is designated the
Centropleura faunule from its most characteristic trilobite. The list
of species was given in the discussion of the locality. Three of the
species, Bathyuriscus eboracensis, Corynexochides? expansus, and
Hypagnostus parvifrons, are common to the Stockport Station
faunule. In Sweden, Centropleura occurs (Westergard, 1953) in the
Solenopleura brachymetopa zone (C2) of the Paradoxides forch-
hammeri stage. This occurrence would suggest that the bed at Judson
Point is somewhat younger than the Bathyuriscus eboracensis bed at
Stockport Station, which was tentatively correlated with zone B4 of
Sweden from the presence of Ptychagnostus punctuosus.

The faunule from Judson Point, like the preceding, contains a mix-
ture of genera of Pacific biofacies (Bathyuriscus, Baltagnostus),
Atlantic biofacies (Centropleura), and cosmopolitan Agnostids (Hy-
pagnostus). A fauna of somewhat similar composition was described
by Howell (1937) from the St. Albans Shale of northwestern Ver-
mont and designated the Centropleura vermontensis fauna. This was
the only previously known occurrence of Centropleura in the United
States. The faunule of the St. Albans Shale was recently revised by
Shaw (1966).

The third faunule of late Middle Cambrian age was collected from

26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

a sandy limestone bed at Nutten Hook (coll. cs-22). Several
ptychoparioid trilobites occur in this faunule, but as they are repre-
sented by fragmentary, meraspid cranidia and pygidia, they are not
even generically identifiable. Some of these trilobites would be sug-
gestive of an early Late Cambrian age. However, the occurrence of a
species of Pegmatreta common to the Stockport Station and Judson
Point faunules is strong indication for a late Middle Cambrian age.
Among the other trilobites, Baltagnostus angustilobus is similar to
B. stockportensis from Stockport Station. Hypagnostus parvifrons
is common to the Stockport Station and Judson Point faunules and is
a well-known late Middle Cambrian trilobite. Gomagnostus is a charac-
teristic genus of the Paradoxides forchhammeri stage in Scandinavia.
The Agnostid pygidium no. 1, an unusual form not referable to de-
scribed genera, is common to the Judson Point faunule. Therefore,
the faunule from Nutten Hook should definitely be referred to the
late Middle Cambrian. The biofacies seems again intermediate be-
tween the Acado-Baltic and Pacific provinces, since Goniagnostus
is characteristic of the former, Baltagnostus of the latter, and Hy-
pagnostus is a cosmopolitan genus.

SYSTEMATIC DESCRIPTIONS

The repositories of the fossils described herein are abbreviated as
follows: USNM (U.S. National Museum) ; GSC (Geological Survey
of Canada) ; MCZ (Museum of Comparative Zoology, Harvard Uni-
versity). NYSM (New York State Museum, Albany). All the ma-
terial collected by the writer was deposited in the U. S. National
Museum. .

The abbreviations (tr.) for transverse, (sag.) for sagittal, and
(exsag.) for exsagittal, qualify such terms as “wide,” “short,” etc.,
whenever the direction of the measurement might be misinterpreted.

All described and figured specimens show the outer surface of the
test unless otherwise indicated.

Order AGNOSTIDA
Family AGNOSTIDAE McCoy, 1849
Genus LEIOPYGE Hawle and Corda, 1847
Type species: Battus laevigatus Dalman, 1828.
LEIOPYGE)?, species no. 1
Plate 9, figures 31, 32

Available material—oOne cephalon.
Description—Cephalon ovate, somewhat narrowed anteriorly. Very

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 27

shallow furrows define the basal lobes at the side. Posterior border
well defined, lateral and anterior border very narrow, defined by a
shallow border furrow, not visible in dorsal view on account of the
steep slope of the shield near the margin. Length of cephalon 3.2 mm.,
width 2.7 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

Discussion.—The specimen very closely resembles Leiopyge calva
Robison (1964a) differing only in the slightly narrower shape. How-
ever, smooth agnostid cephala are difficult to classify in the absence of
the pygidium. Hence even the generic reference remains doubtful,
especially in view of the fact that the associated trilobites suggest that
the Stockport Station bed is older than the strata where Leiopyge
occurs in Scandinavia and the western United States. From the
cephalon alone it is difficult to distinguish Leiopyge from such species
as “Phalacroma’ marginatum and “P.” glandiforme, illustrated by
Westergard (1946), which occur in somewhat older beds. As the re-
cent work of Snajdr (1958) and Gpik (1961) has shown, these
Agnostids do not belong in Phalacroma, and even the reference to
Phalagnostus seems questionable in view of the considerations sug-
gested herein in discussing the Agnostid pygidium no. 1.

Disposition of material—Figured specimen: USNM 156549.

LEIOPYGE?, species no. 2
Plate 9, figure 33

Available material—One cephalon.

Cephalon proportionately wider and shorter than in preceding
species, of equal width and length, of more nearly subquadrate shape.
Border furrow and border very narrow, but well defined. Basal lobes
defined by very shallow furrows but distinct. Glabella elevated in
posterior portion, defined by a trace of an axial furrow for a short
distance in front of the basal lobes. Length and width of cephalon 1.4
mm.

Discussion.—The specimen falls well within the limits of variability
of Leiopyge laevigata (Dalman) as illustrated by Westergard (1946).
However, in the absence of the pygidium, the same uncertainty pre-
vails as discussed for the preceding species.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

Disposition of material—Figured specimen: USNM 156550.

28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Genus PTYCHAGNOSTUS Jaekel, 1909
Type species: Agnostus punctuosus Angelin, 1851.
PTYCHAGNOSTUS PUNCTUOSUS (Angelin)
Plate 9, figures 28-30

Agnostus punctuosus ANGELIN, 1851, p. 8, pl. 6, fig. 11.

Ptychagnostus (Ptychagnostus) punctuosus (Angelin) WeEstTERGARD, 1946, p. 78,
pl. 11, figs. 34, 35; pl. 12, figs. 1-7. Complete synonymy to date.

Ptychagnostus punctuosus (Angelin) Hutcurinson, 1962, p. 84, pl. 9, figs. 9-19.

Represented in the collection by a fragmentary cephalon and two
fragmentary pygidia. All the visible features, mainly the segmentation
of the glabella and pygidial axis, and the characteristic ornamenta-
tion of coarse granules and scrobiculate cheeks, agree with the speci-
mens illustrated by Westergard.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

Types.—Plesiotypes: USNM 156551.

PTYCHAGNOSTUS GIBBUS (Linnarsson)
Plate 10, figures 1-8

Agnostus gibbus Linnarsson, 1869, p. 81, pl. 2, figs. 52, 53.

Triplagnostus gibbus (Linnarsson) Howe tt, 1935, p. 14.

Ptychagnostus (Triplagnostus) gibbus (Linnarsson) WestercArp, 1946, p. 70,
pl. 9, figs. 17-24. Complete synonymy to date.

Represented in the collections by numerous cephala and pygidia.
The cephalon fully agrees with the types in all features, except that
the posterior border being more or less completely broken off, the
presence of long spines as in the type material cannot be ascertained.
One cephalon shows the base of a spine of unknown length.

The pygidium has the strong, highly elevated node on the second
axial ring, which may be described as a blunt spine, like the Swedish
specimens. The median postaxial furrow is generally deep, shallow
only in some of the larger specimens. Both these features according
to Westergard distinguish the species from P. praecurrens (Wester-
gard), of which Triplagnostus burgessensis Rasetti is regarded as a
synonym.

Occurrence.—Collections cs-9c’ and cs-9d, Malden Bridge, and
loose blocks (cs-7/M1 and others) on the Griswold farm; associated
with other trilobites of the Bathyuriscus-Elrathina zone.

Types.—Plesiotypes: USNM 156552-3.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 29

PTYCHAGNOSTUS, species undetermined
Plate 10, figures 27-31

Available material—A few cephala and pygidia, the latter mostly in
the meraspid stage.

Description—Glabella divided by shallow furrow into elevated
posterior lobe and low frontal lobe, the latter defined by a very shallow
axial furrow, tapering to a sharp point. Preglabellar furrow well
defined. Basal lobes of average size, defined laterally by a shallow
furrow. Border furrow and border both very narrow, but well defined.
Length of largest cephalon 3.2 mm.

Pygidial axis with first lobe wider (tr.) than other lobes, defined
by transverse furrow convex forward. Second lobe in meraspid
pygidia wider medially, since both defining furrows turn the con-
cavity toward it; in holaspid pygidium this portion of the axis is not
well preserved, but the second lobe is seen to bear a tubercle near its
posterior margin. Posterior lobe tapered to a rather sharp point.
Postaxial furrow shallow. Pygidial border considerably wider than
cephalic border, defined by well-impressed furrow. Length of largest
pygidium 2.4 mm. Surface smooth.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

Discussion.—As far as can be ascertained from the small or not well
preserved specimens, this form does not appreciably differ from
Ptychagnostus elegans (Tullberg) as illustrated by Westergard
(1946).

Disposition of material—Figured specimens: USNM 156554.

Genus GONIAGNOSTUS Howell, 1935
Type species : Agnostus nathorsti Brogger, 1878.
GONIAGNOSTUS, species undetermined
Plate 9, figures 18, 19

Available material_—Fragments of two cephala.

Description.—Glabella in posterior portion divided into strongly
elevated median lobe and lower lateral lobes, the distinction becoming
effaced toward the front and disappearing in the frontal lobe. Frontal
lobe rapidly tapered to a sharp point, not elevated above the genae,
defined by narrow, well-impressed axial and transverse furrows; the
latter shallower medially. Remainder of glabella markedly divided, at
least in the lateral portions, into three lobes of approximately equal

30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

lengths. These lobes are distinguishable not only by the furrows that
divide them, but also by the outwardly convex course of the axial
furrow around each separate lobe. The first pair of lateral furrows
after the transverse furrow which separates the frontal lobe is straight,
well impressed laterally, but not across the elevated, median part of
the glabella. The next pair of furrows has the form of a pair of deep
pits adjacent to the elevated, median lobe, connecting with the axial
furrow through a shallow, transverse furrow. The lateral parts of
the glabella posterior to this pair of furrows should probably be
interpreted as the basal cephalic lobes, which in more primitive
Agnostids are part of the occipital ring, being continuous with its
median portion and well separated from the glabella (Rasetti and
Theokritoff, 1967). However, in certain forms of Ptychagnostus and
Goniagnostus the basal lobes assume the aspect of lateral parts of the
posterior glabellar lobe (Westergard, 1946). Unfortunately in the
present form the basal lobes are incomplete in their outer portion.
The elevated, median lobe of the glabella slopes down steeply to a
narrow (long.) band that tapers at the sides, and must represent part
of the occipital ring. There is a very narrow median ridge on the
downsloping, rear portion of the glabella. The specimen showing all
these features shows but small portions of the innermost areas of the
genae, and a few scrobicules are seen to radiate from the axial furrow.
The other fragment represents part of the frontal glabellar lobe and
the anteriormost area of the genae up to the border furrow; no portion
of the border is preserved. The genae are divided by a narrow, well-
impressed median furrow reaching the border furrow, and show
several narrow, well-impressed scrobicules. The surface of the test,
aside from the scrobicules, is ornamented by an exceedingly fine gran-
ulation, observable only on coated specimens under high magnification.
Length of glabella 2.6 mm.

Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook.

Discussion—Even though the cephalon is represented only by
fragments, and the pygidium is unknown, this Agnostid may be con-
fidently referred to Goniagnostus since the glabellar lobation is es-
sentially of the type occurring in the type species (Westergard, 1946,
pl. 12, figs. 12-16), the present form being only somewhat more ex-
treme in its unusual features. The genus occurs in Sweden in zones
Cl and C2 of the Paradoxides forchhammeri stage, being more com-
mon in the former. This fact tends to confirm the suggested approxi-
mate correlation of the fossiliferous bed at Nutten Hook with the
Centropleura bed at Judson Point.

Disposition of material—Figured specimens: USNM 156555.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 31

Family PERONOPSIDAE Westergird, 1935
Genus PERONOPSIS Hawle and Corda, 1847
Type species: Battus integer Beyrich, 1845.
PERONOPSIS, species no. 1
Plate 10, figures 9-12

Available material—Several pygidia, and a cephalon tentatively
referred to the same species.

Description ——Glabella divided by deep transglabellar furrow.
Frontal lobe slightly narrower than posterior lobe, semicircular, well
defined by axial furrow. Posterior lobe more than twice longer than
anterior lobe, widest in front, narrowed toward the rearward portion
which is well rounded, with a barely indicated node in advance of the
midpoint. A pair of lateral furrows as indentations some distance be-
hind the transglabellar furrow; there seems to be also a shorter in-
dentation corresponding to the anterior end of the basal lobes. The
latter, conspicuous, subtriangular. Border furrow wide, especially
anteriorly; border narrow. Length of cephalon 3.7 mm. Surface
smooth.

None of the pygidia preserve the test. Axis wide, not quite reaching
the border furrow, with first and second lobe defined by two pairs of
lateral furrows; anterior lobe somewhat wider (tr.) than second
lobe. Second lobe with a prominent, elongate tubercle slightly ex-
tending beyond the second pair of furrows. Axis fairly pointed
posteriorly. General shape of pygidium subquadrate, on account of
the widening of the border at the position of the marginal spines and
consequent fairly straight lateral outline. Border furrow wide, border
also wide; spines short. Length of largest pygidia 3 mm.

Occurrence.—Collection cs-9d (Bathyuriscus-Elrathina zone),
Malden Bridge.

Discussion—This form might well be included in Peronopsis fallax
(Linnarsson) as illustrated by Westergard (1946) but for the fact
that it seems to possess better defined lateral furrows on the pygidial
axis. Furthermore, neither identification with a described species, nor
proposing a new one, seems proper in view of the uncertain reference
of the cephalon to the pygidia. Two types of pygidia occur at the
locality, but the two cephala could not always be distinguished with
certainty, in part owing to poor preservation. The more common
cephalon was tentatively combined with the more common pygidium.

Disposition of material—Figured specimens: USNM 156556.

32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

PERONOPSIS, species no. 2
Plate 10, figures 13-18

Available material—Numerous cephala and pygidia, all poorly
preserved.

Description.—Glabella of the same proportions as in preceding
species, with frontal lobe slightly wider than posterior lobe. One pair
of lateral furrows barely indicated on posterior lobe, which has an in-
distinct, elongated tubercle near its midpoint. Basal lobes as in pre-
ceding species. Border furrow moderately wide, border narrow.
Length of larger cephala 2.5 mm.

Pygidial axis relatively narrow, reaching maximum elevation at
second lobe, sloping down to pointed posterior end, reaching border
furrow. Lateral furrows of first pair very short and shallow, of second
pair indistinct. A low, elongated tubercle on the second lobe. Border
furrow moderately wide and fairly deep, regularly curved. Border of
moderate and fairly uniform width, barely showing a slight widening
at the position where spines are located in similar species. Length of
pygidium 2.4 mm.

Occurrence.—In the same bed as the preceding species: collection
cs-9d (Bathyuriscus-Elrathina zone), Malden Bridge.

Discussion.—This form resembles Peronopsis scutalis (Hicks) as
figured by Westergard (1946) in the lack of pygidial spines and non-
confluent pleural regions behind the axis. The same reasons mentioned
for the preceding species make a positive identification inadvisable.

Disposition of material_—Figured specimens: USNM 156557.

PERONOPSIS, species no. 3
Plate 10, figures 19-21

Available material—A few, poorly preserved cephala and pygidia.

Description.—Glabella with both lobes of equal width. Frontal lobe
somewhat wider than long. Posterior lobe parallel-sided, showing
vaguely a pair of lateral indentations somewhat in front of the
middle, and a faint tubercle about two-thirds of the distance from the
transglabellar furrow. Basal lobes lower and narrower than in the
two preceding species. Border furrow and border narrow. Length
of cephalon 0.75 mm.

Pygidia much larger, up to 3.5 mm. in length. Axis about parallel-
sided in anterior two-thirds, then tapered to a sharp point, not reaching
border furrow.

First pair of lateral furrows impressed at the sides, causing a slight

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 33

constriction of the axis; second pair barely indicated. A low tubercle
on the second axial lobe. Pleural regions confluent behind the axis.
Border furrow moderately wide and deep; border expanded laterally
but not extended into spines.

Occurrence.—Collections cs-6 (Bathyuriscus-Elrathina zone),
Griswold farm.

Discussion —This form is typical of Peronopsis, being somewhat
intermediate between the two preceding ones, although it differs from
both in the confluent pleural regions. The location of the node on the
glabella is a distinguishing characteristic. In view of the scarcity of the
material and immature condition of the available cephala, identification
with described species is not suggested.

Disposition of material_—Figured specimens: USNM 156558.

PERONOPSIS, species no. 4
Plate 9, figure 26

Available material—A small cephalon.

Description.—Frontal glabellar lobe as wide as posterior lobe, twice
wider than long, defined by shallow transglabellar furrow showing
a median forward bend. There is a suggestion of a notch on the front
of the glabella. Posterior lobe rising and slightly narrowing toward
the rear, lacking distinct node. Basal lobes low, rather wide (tr.) and
short (exsag.). Border furrow and border narrow. Length of
cephalon 0.9 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

Discussion—Among the agnostid cephala recovered at the locality,
the present one is distinctive, especially in the course of the trans-
glabellar furrow. In the absence of a pygidium even generic identifica-
tion is not certain.

Disposition of material—Figured specimen: USNM 156559.

PERONOPSIS, species no. 5
Plate 7, figures 17, 18

Available material—A fragmentary cephalon and a fragmentary
pygidium.

Description.—Posterior glabellar lobe parallel-sided in anterior two-
thirds, in the rear narrowing to a blunt point, reaching but not over-
hanging the posterior cephalic margin. Transverse furrow slightly
concave toward the front, well impressed. Axial furrow well im-

34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

pressed around frontal lobe, which is well rounded and 1.5 times wider
than long. Occipital ring in form of long (tr.) and narrow (exsag.),
subtriangular lobes, well defined by axial furrow laterally, completely
separated medially by the rearward extension of the glabella. Other
cephalic parts not preserved.

Pygidial axis well defined by axial furrow, expanding backward in
anterior half, rearward tapered to a sharp point, almost reaching the
posterior border furrow which connects with the axial furrow through
a short median depression. No other features of the axis besides the
outline are preserved. Pleural regions narrow (tr.), downsloping.
Anterior border furrow well impressed; anterior border widest at
geniculation, which is situated close to axial furrow, much reduced
distally. Border furrow and posterolateral border well defined ; border
wide, of almost uniform width, lacking spines. Length of pygidium
1.7 mm. Cephalon and pygidium lie very close to each other on the
rock surface and are likely to belong to one individual.

Occurrence.—Lower Cambrian Neopagetina faunule; collection
cs-9 at the Malden Bridge road cut.

Discussion.—Several features clearly distinguish the species from
the few known Lower Cambrian Agnostids (Rasetti and Theokritoff,
1967). The main characteristics of the cephalon are the curved
transverse furrow and the complete separation of the basal lobes.
The pygidium is distinctive in the long axis and wide border. Un-
fortunately, intensive search for Agnostids at all known Lower Cam-
brian fossil localities in the East Chatham quadrangle produced, in
addition to the specimens under discussion, less than half a dozen
cephala, all seemingly referable to Peronopsis, but more similar to
Peronopsis primigenea (Kobayashi) and an allied form described
from Washington County (Rasetti and Theokritoff, 1967).

Disposition of material —Figured specimens: USNM 156560.

Genus HYPAGNOSTUS Jaekel, 1909
Type species: Agnostus parvifrons (Linnarsson), 1869.

HYPAGNOSTUS PARVIFRONS (Linnarsson)
Plate 9, figures 23-25

Agnostus parvifrons LINNARSSON, 1869, p. 82, figs. 56, 57.

Hypagnostus parvifrons (Linnarsson) CoppoLp and Pocock, 1934, p. 343, pl. 44,
figs. 13-19,

Hypagnostus parvifrons (Linnarsson) WEsTERGARD, 1946, p. 45, pl. 4, figs. 27-31.
Complete synonymy to date.

Hypagnostus metisensis RAsEtTI, 1948b, p. 320, pl. 45, figs. 21-27.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 35

Hypagnostus parvifrons (Linnarsson) Hutcuinson, 1962, p. 73, pl. 6, figs.
6a-b, 7.
Hypagnostus parvifrons (Linnarsson) Rosison, 1964a, p. 529, pl. 81, figs. 4-23.

Represented in the collections by a few cephala, which do not differ
in any visible feature from those described and figured from the type
area.

Occurrence.—Collections cs-21, Stockport Station; cs-22, Nutten
Hook; and cs-23, Judson Point. The faunules at all three localities are
attributed to the Bolaspidella zone.

Types.—Plesiotypes: USNM 156561-3.

HYPAGNOSTUS, species undetermined
Plate 9, figure 27

Available material—aAn immature cephalon.

Description.—Posterior glabellar lobe parallel-sided, elevated pos-
teriorly, truncate in front, with a low node in posterior part, showing
a trace of lateral furrows. Frontal lobe effaced. Basal lobes low,
subtriangular. Border furrow well impressed, border moderately wide.
Length of cephalon 0.78 mm., width 0.72 mm.

Occurrence.—Collection cs-22, Nutten Hook.

Discussion—The specimen resembles Hypagnostus truncatus
(Brogger) as illustrated by Westergard (1946), but even the generic
reference is uncertain lacking an associated pygidium. From the
cephalon alone, Hypagnostus and Kormagnostus are difficult to
distinguish.

Disposition of material_—Figured specimen: USNM 156564.

Family DIPLAGNOSTIDAE Whitehouse, 1936
Genus BALTAGNOSTUS Lochman, 1944
Type species: Proagnostus? centerensis Resser, 1938.
BALTAGNOSTUS ANGUSTILOBUS, new species
Plate 9, figures 4-11

Available material_—Several small holaspid cephala and pygidia.

Description.—Glabella sloping from a strongly elevated, posterior
portion to a low anterior end. Frontal lobe small, about half the
maximum width of posterior lobe, about as wide as long, slightly
pointed in front, defined by well-impressed transverse and axial
furrows, not rising above the level of the genae. Posterior lobe
slightly tapered forward, reaching maximum elevation near posterior

36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

end, tapered backward to a rounded rear end. Occipital ring con-
sisting of fairly wide (sag.) median band, concealed in dorsal view by
glabella, and unusually large basal lobes. There is no distinct node on
the glabella. Genae of moderate convexity; there is a faint, short
median preglabellar furrow fading out well before reaching border
furrow. Border furrow well impressed; border wide. Surface finely
and rather indistinctly granulate.

Pygidium with strongly prominent axis showing but traces of
segmentation. Anterior segment tapered backward; second segment
slightly narrower; terminal segment usually as wide as second seg-
ment, in some specimens expanded posteriorly, well rounded at rear
end, almost reaching the broad border furrow. There is a node at the
posterior end of the second axial segment. Border furrow wide and
relatively shallow, slightly inflected forward medially. Border wide,
rather flat, widest medially, extended into a pair of flat, broad, short
spines. Ornamentation indistinct. Cephala and pygidia, probably im-
mature, not exceeding 1 mm. in length.

Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook.

Discussion.—This species seems to fit in Baltagnostus better than in
other described genera, even though it does not entirely conform to
the diagnosis of the genus recently given by Robison (1964a), since
the pygidial border does not have the characteristic crescentic shape,
and the glabella lacks a node on the posterior lobe. Neither, however,
appears to be a sufficiently important feature to exclude the species
from the genus. Compared with B. eurypyx Robison, the best-known
species of the genus, B. angustilobus differs in the narrow frontal
glabellar lobe, great elevation of posterior lobe, lack of median node,
proportionally shorter and somewhat narrower pygidial axis.

Types.—Holotype: USNM 156565. Paratypes: USNM 156566.

BALTAGNOSTUS STOCKPORTENSIS, new species
Plate 9, figures 12-17, 22

Available material_—Several small holaspid cephala and pygidia.

Description.—Glabella moderately elevated posteriorly. Frontal
lobe almost semicircular, about two-thirds the width of posterior lobe,
well defined by axial and transverse furrows but not rising above the
level of the genae. Posterior lobe parallel-sided, abruptly constricted
to a pointed posterior end; showing an elongated, low node on its
posterior portion. Occipital ring expanded into basal lobes somewhat
smaller than in preceding species; median portion almost entirely
visible in dorsal view. Genae of moderate convexity; median pre-

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 37

glabellar furrow shallow, fading out anteriorly. Border furrow well
impressed, border of moderate width.

Pygidial axis strongly elevated, slightly tapered backward in an-
terior portion, well rounded posteriorly, almost reaching the wide
border furrow. Segmentation of axis indistinct; median node not
very prominent, slightly posterior to midpoint. Border furrow wide
and shallow, somewhat inflected forward medially. Border increasing
in width toward the rear, widest medially, somewhat crescent-shaped,
extended into a pair of short spines. Surface of test of cephalon and
pygidium smooth. Length of largest cephalon 2 mm., of other cephala
and pygidia averaging about 1 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

Discussion.—This species is more typical of the genus than the pre-
ceding, most of the differences occurring in the cephalon. Compared
with B. eurypyx Robison, B. stockportensis differs in the narrowness
of the frontal glabellar lobe, and somewhat shorter and narrower
pygidial axis. Compared with B. angustilobus, the present species
differs chiefly in the wider frontal glabellar lobe, less elevated posterior
portion of glabella, presence of a node on posterior glabellar lobe, and
slightly more posterior location of the node on the pygidial axis.

Types.—Holotype: USNM 156567. Paratypes: USNM 156568.

Family undetermined
Genus GRANDAGNOSTUS Howell, 1935

Type species: Grandagnostus vermontensis Howell, 1935.

Opik (1961) has given the most recent discussion of the Agnostids
with effaced axial furrows. Grandagnostus differs from Phalagnostus
in the effaced basal cephalic lobes. No satisfactory family assignment
seems available for these genera once Opik correctly removed them
from the Phalacromidae.

GRANDAGNOSTUS), species undetermined
Plate 9, figures 20, 21

Available material—One cephalon.

Description—Cephalon convex, widest about the middle, well
rounded in front. All furrows totally effaced, but for a slightly differ-
entiated, subtriangular portion of the posterior border, Length 1.5
mm., width 1.36 mm.

38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Occurrence.—Collection cs-23 (Centropleura faunule), Judson
Point.

Discussion—The cephalon closely resembles species of Grand-
agnostus figured by Opik (1961). However, even the generic reference
is uncertain owing to lack of the pygidium.

Disposition of material_—Figured specimen: USNM 156569.

Genus undetermined
Agnostida, pygidium no. 1
Plate 10, figures 22-26

Available material_—About a dozen specimens.

Description.—Pygidium with well-developed articulating half-ring
and anterior border furrow, the latter setting off an anterior border
which becomes effaced before attaining the lateral margin. Lateral
and posterior border lacking. Axis unfurrowed, elevated, defined by
a deep furrow all around, occupying about half the width and from
two-thirds to three-fourths the length of the pygidium, tapering back-
ward to a narrowly rounded point. There is a bare suggestion of a
median node. Pleural regions convex marginally, downrolled. Length
of largest pygidium 1 mm.

Occurrence.—Collections cs-23 (Centropleura bed), Judson Point,
and cs-22, Nutten Hook.

Discussion.—To the writer’s knowledge, no agnostid pygidium has
been described in the literature as lacking a border. However, it
seems possible that such is the case for the pygidia of Phalagnostus
(referred by Westergard to Phalacroma), in particular Phalagnostus
scanicus (Tullberg) figured by Westergard (1946, pl. 14, figs. 16-18)
and P. nudus (Beyrich) figured by Snajdr (1958, pl. 5, figs. 1-24) and
Hutchinson (1962, pl. 11, figs. 6-8). In these Agnostids the wide rim
around the pygidium has been described as the border. This interpre-
tation, however, seems questionable because the anterior border
furrow and border are well developed, but the former crosses the
supposed lateral “border” instead of extending into the lateral border
furrow as in all other Agnostids. Therefore the writer tentatively
suggests as an alternative interpretation that these Agnostids lack
lateral and posterior border.

According to Westergard (1946) in Phalagnostus marginatus
(Brogger) the anterior border furrow does not cross the “border,”
even though in other respects the species appears very similar to P.
scanicus. In “Phalacroma” glandiforme (Angelin) the anterior border

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 39

furrow clearly merges with the lateral border furrow, leaving no doubt
that in this species we are dealing with a true border. Therefore, if
the suggested interpretation is correct, the pygidia of P. scanicus and
P. glandiforme would have substantially different structure and could
not be referred to the same genus. The writer, fully aware of the
pitfalls of interpretations based on illustrations (even as excellent
as those under discussion), refrains from drawing any definitive con-
clusions ; and to the paleontologists who have access to the relevant
material from Sweden, Bohemia, and Newfoundland suggests further
study in the light of these remarks.

The pygidia described herein unquestionably lack a border, and the
elevated, central portion has the usual structure of an axis, rather than
the peculiar subcircular shape observed in Phalagnostus. The latter
structure must be considered a “pseudolobe” resulting from fusion of
the axis and the pleural platforms, or only part of the latter according
to the suggested interpretation.

The present species cannot be considered congeneric with any
described Agnostid, but it would be improper to propose a new genus
without an associated cephalon,

Disposition of material—Figured specimens: USNM 156570-1.

Agnostida, pygidium no. 2
Plate 10, figure 35

Available material—One specimen.

Description—Pygidium of unusually low convexity, parallel-sided,
well rounded posteriorly, somewhat longer than wide. Axis unde-
fined, possibly with a very low tubercle in anterior part. Pleural plat-
forms slightly down-sloping to a broad border furrow. The border
furrow is sharply defined along the anterior pygidial margin, which
has an unusually strong backward slant, turns sharply into the lateral
border furrow which becomes progressively wider and shallower
toward the rear, and almost disappears medially where there is but a
vague distinction between the pleural platforms and the wide border.
Length of pygidium 2.4 mm.

Occurrence.—Collection cs-23 (Centropleura bed), Judson Point.

Discussion—This pygidium is unusual in the low convexity,
parallel-sided shape, and strongly slanted anterior outline of the
pleural lobes. Too little is known to suggest significant comparisons
with described genera.

Disposition of material—Figured specimen: USNM 156572.

40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Order EODISCIDA
Family EODISCIDAE Raymond, 1913

The Lower Cambrian strata in the East Chatham quadrangle
continued to supply new forms of Eodiscidae, in addition to 19 named
and 3 unnamed species described (Rasetti, 1966a) from the Aci-
metopus bilobatus bed. Some of these new Eodiscidae occur in associa-
tion with the Acimetopus fauna, others are members of the Pagetides
fauna. Four new named species and 10 unnamed ones are described
herein, the latter too poorly represented to warrant proposing new
genera and species. Including 3 species of Eodiscidae described be-
fore 1966, Calodiscus lobatus, C. walcotti, and Serrodiscus speciosus,
the Lower Cambrian strata of the East Chatham quadrangle are
known to contain at least 39 species of Eodiscidae, a number vastly
exceeding the species of the family previously known from North
America, and also greater than the number of species described from
the rest of the world.

To avoid nomenclatural confusion, no taxa were based on pygidia,
even if well preserved and clearly distinct from named species.

Cephala and pygidia of uncertain generic reference are designated by
numbers. Numbers used in the previous paper (Rasetti, 1966a) are
not used again in a different meaning, to avoid confusion in the faunal
lists. Thus the first unassigned pygidium in the present paper is no. 5,
since numbers 1-4 were previously used.

Genus ACIDISCUS Rasetti, 1966
Type species: Acidiscus birdi Rasetti, 1966.
ACIDISCUS BIRDI Rasetti
Plate 2, figure 4
Acidiscus birdi Rasett1, 1966a, p. 11, pl. 1, fig. 2; pl. 6, figs. 11-19.

An additional, large cephalon collected at the type locality shows
one feature that was overlooked in describing the species. The pos-
terior cephalic border, between the axial furrow and the genal spine,
possesses an articulating feature similar to that described in Lito-
metopus longispinus and Serrodiscus subclavatus. A narrow furrow
sets off a triangular ridge, widening distally into a slight projection
of the otherwise straight posterior margin.

Occurrence.—The type locality is cs-4, Griswold farm. Rare, frag-
mentary specimens also in collection cs-9a near Malden Bridge.

Types.—Holotype: USNM 145987. Paratypes: USNM 145988.
Plesiotype figured herein: USNM 156573.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 4I

ACIDISCUS HEXACANTHUS Rasetti
Plate 2, figures 1-3
Acidiscus hexacanthus Rasettt, 1966a, p. 13, pl. 7, figs. 1-6.

A pygidium from the type locality is illustrated in order to show the
excellently preserved ornamentation, consisting of granules enclosed
in the meshes of an irregular, reticulate pattern of raised lines.
Ornamentation in the pygidia of A. birdi and A. hexacanthus seems
to vary from an almost entirely smooth test to the kind illustrated
herein, making it difficult to classify some specimens.

Occurrence.—Collection cs-4, Griswold farm.

Types.—Holotype: USNM 145989, Paratypes: USNM 145990.
Plesiotype figures herein: USNM 156573.

Genus ANALOX Rasetti, 1966
Type species: Analox bipunctata Rasetti, 1966.
ANALOX OBTUSA, new species
Plate 2, figures 5-7

Available material—A few cephala and pygidia.

Description—Cephalon somewhat wider than long (excluding the
glabellar spine), fairly convex. Glabella divided by deep, straight
transverse furrow into a tapered, rounded anterior lobe and a larger,
fusiform posterior lobe strongly elevated posteriorly and projecting
well beyond the posterior outline of the cephalon. This glabellar ex-
tension, however, is not as pronounced as in A. bipunctata and is more
bluntly rounded distally. Occipital ring present, narrow (sag.), almost
hidden in dorsal view. Genae convex, lacking lateral border. A pair of
furrows diverge from the anterior part of the axial furrow and end
in a pair of pits some distance from the anterior cephalic margin.
Posterior border set off by deep border furrow; genal angle seemingly
not extended into spine.

Pygidium somewhat wider than long. Axis well defined by the axial
furrow, but not much elevated above the pleural lobes, moderately
tapered, composed of 4 well-defined rings plus a terminal, unseg-
mented section, ending a short distance from the pygidial margin.
Anterior border furrow on pleural regions deep and wide; lateral and
posterior border exceedingly narrow, set off by an equally narrow
furrow. Doublure forming a vertical face as in A. bipunctata, Sur-
face more or less distinctly pitted. Length of largest cephalon, includ-
ing glabellar extension, 3.2 mm., of largest pygidium 2.7 mm.

42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Occurrence.—Associated with the Pagetides fauna in collections
cs-3/L2 and cs-3/L3.

Discussion—The species can be clearly distinguished from A.
bipunctata by the proportionately wider cephalon, wider glabella,
deeper transglabellar furrow, lesser rearward extension of the glabella,
and the smaller number of segments in the pygidial axis.

Types.—Holotype: USNM 156575. Paratypes: USNM 156576.

Genus BOLBOPARIA Rasetti, 1966
Type species: Bolboparia superba Rasetti, 1966.
BOLBOPARIA CANADENSIS Rasetti
Plate 2, figures 13, 14
Bolboparia canadensis RaseEtt1, 1966a, p. 21, pl. 5, figs. 13, 14.

A single pygidium, collected by G. Theokritoff from the type locality,
almost certainly belongs to the species, on account of the close re-
semblance to the pygidium of B. elongata previously described.

Axis narrow, tapered, almost reaching the border furrow, composed
of about 14 rings plus a terminal section, the precise number uncertain
due to imperfect preservation of the posterior portion. A strong,
rapidly tapered, upright spine on the second ring as in B. elongata.
Pleural regions unfurrowed, apart from the well-impressed anterior
border furrow, rather flat medially but sloping down vertically in
the marginal portion and concealing in dorsal view the border furrow
and most of the border. Border furrow wide and well impressed;
border moderately wide, slightly decreasing in width rearward, ver-
tical, extended into about 10 pairs of short, downward-directed spines
of decreasing length. Surface of axis and pleural regions densely
covered with granules of different sizes, the larger ones presumably
representing the bases of short spines ; border with small granules only.
Length of pygidium 7.5 mm., width 8.0 mm.

Occurrence.—Limestone beds 4 mile north of Elgin Station,
L’Islet County, Quebec (Hubert’s locality 63-F24).

Types.—Holotype: GSC 19887. Plesiotype figured herein: GSC
10563.

BOLBOPARIA, species no. 1

Plate 2, figures 8-12

Available material—Two fragmentary cephala and a fairly com-
plete pygidium, plus fragments of silicified pygidia.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 43

Description—Cephalon, as far as can be observed, having the
general features of the genus, including the tapered glabella, pre-
glabellar depression, lateral border with a pair of marginal spines,
and subtriangular posterior border, the posterior border furrow
running outward and forward as in other species. Ornamentation
consisting of small granules and short spines observable only on
silicified fragments. Length of cephalon 4.5 mm.

Pygidium with tapered axis not reaching border furrow. Axis
seemingly composed of not more than 7 or 8 rings, defined by shallow
ring furrows; there was a large spine on the second ring as in other
species. Axial furrows deep; pleural regions rising above axial
furrows, rather flat in proximal portion, sloping down vertically at
the sides and concealing at least part of the lateral border in dorsal
view. Border steeply down-sloping, extended into several pairs of
small spines not visible from above; border furrow well impressed.
Ornamentation same as cephalon. Length of pygidium 2.7 mm., width
3.2 mm.

Occurrence.—Collection cs-9a (Leptochilodiscus punctulatus bed)
in the Malden Bridge road cut.

Discussion —The cephalon, compared with B. superba, appears to
have a proportionately longer, less rapidly tapered glabella, and the
genae are less bulging and more rounded in outline. The pygidium,
compared with the known pygidia of B. elongata and B. canadensis,
has the same general structure, but differs markedly in the much lesser
number of axial segments and the greater proportional width.

Disposition of material—Figured specimens: USNM 156577 (the
pygidium on same piece of rock with a plesiotype of Leptochilodiscus
punctulatus).

BOLBOPARIA, species no. 2
Plate 2, figure 15

Represented by a single example, a poorly preserved pygidium.
The pygidium is wider than long, and has a narrow, multisegmented
axis on which 9 or 10 rings are visible on the incomplete, preserved
portion. There may have been a spine on the second segment. Pleural
lobes unfurrowed, aside from the well-impressed anterior border
furrow ; other portions of border not preserved. Ornamentation con-
sisting of relatively large granules, appearing as broken spines, plus
smaller granules. Length of pygidium about 3 mm.

Occurrence.—Loose Lower Cambrian block cs-15/L4, in wooded

44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

area north of the Griswold farm, in association with a Pagetides
faunule.
Disposition of material—Figures specimen: USNM 156578.

Genus CALODISCUS Howell, 1935
Type species: Agnostus lobatus Hall, 1847.
CALODISCUS LOBATUS (Hall)
Plate 3, figures 2-6

Agnostus lobatus Hatt, 1847, p. 258, pl. 57, figs. 5a-f.

Calodiscus lobatus (Hall) Howe tt, 1935, p. 224.

Calodiscus lobatus (Hall) Raserrt, 1952, p. 441, pl. 51, figs. 1-11. Complete
synonymy to date.

Calodiscus lobatus (Hall) Locuman, 1956, p. 1378, pl. 8, figs. 1-11.

The species is one of the most common and characteristic forms
of the Elliptocephala asaphoides assemblage in the entire Taconic
sequence from northern Washington County to northern Columbia
County. In the East Chatham quadrangle the occurrence in the
conglomerate at Ashley Hill was cited by Lochman (1956). Here the
presence of the species in other faunal assemblages is reported. The
cephala from the new localities fall well within the wide limits of
variability observed within the Elliptocephala asaphoides assemblage.

Occurrence.—Several silicified cephala and pygidia were etched with
hydrochloric acid from limestone of the Leptochilodiscus bed (collec-
tion cs-9a) at the Malden Bridge road cut. A single cephalon, also
illustrated herein, was found in association with a Pagetides faunule
(coll. cs-18).

Types.—Figures plesiotypes: USNM 156579-80.

CALODISCUS THEOKRITOFFI, new species
Plate 2, figures 16-19

Available material—aA cephalon from the type locality in Quebec
and a few, fragmentary, silicified cephala from Columbia County.

Description.—Glabella deeply divided into anterior and posterior
lobes by wide transglabellar furrow. Anterior lobe about equally wide
and long, tapered, rounded in front, almost reaching the border
furrow. Posterior lobe strongly elevated posteriorly, rounded at the
top, extending rearward somewhat beyond the general outline of the
cephalon, overhanging the occipital ring which remains visible in
dorsal view only at the sides. Occipital ring strongly curving forward
laterally, narrow, lacking spine. Genae very convex, in posterolateral

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 45

part overhanging the border furrow, divided in front of the glabella
by an exceedingly short (sag.) depression. Border furrow semi-
circular, not appreciably indented backward medially, well impressed
throughout, very deep posterolaterally, connecting with deep posterior
border furrow which is slanted outward and forward from the axial
furrow. Anterior and lateral border in a horizontal plane, slightly
convex, tapering from maximum width medially to a minimum near
genal angle. Doublure wide, especially in median part, reflexed to
parallel the dorsal test. Posterior border subtriangular, wide distally
where it extends into a short spine, at higher level than lateral border.
Surface finely and rather indistinctly reticulate. Length of holotype
cephalon 4.6 mm.

Occurrence.—The type locality is Hubert’s locality 63-F24, lime-
stone beds 4 mile N. of Elgin Station, L’Islet County, Quebec. Para-
types were etched from the Leptochilodiscus beds (coll. cs-9a) at the
Malden Bridge locality.

Discussion.—This species is very similar to C. reticulatus Rasetti
which is also a member of the Acimetopus bilobatus fauna. It differs
mainly in the flatter border which is regularly curved, lacking median
inbend, and in the much lesser rearward extension of the glabella,
even though the last feature may have been exaggerated in the restora-
tion of C. reticulatus (Rasetti, 1966a, pl. 1, fig. 1).

Types.—Holotype: GSC 10564. Paratypes: USNM 156581.

CALODISCUS WALCOTTI Rasetti
Plate 1, figure 4; plate 3, figures 7-10
Calodiscus walcotti RAsEtt1, 1952, p. 443, pl. 54, fig. 17.

Available material—Previously known only from the holotype
cephalon. Several additional cephala and associated pygidia were
collected, allowing a more complete description. The new material,
even though preserved in limestone, is somewhat flattened.

Description.—Regarding the cephalon, it is only necessary to correct
the statement that the “occipital ring and posterior glabellar lobe
[are] apparently extended together into a strong spine, broken off in
the available specimen.’ Some of the new cephala preserve the pos-
terior part of the glabella, which is considerably elevated, but rounded,
sloping down vertically to the occipital furrow. The latter is im-
pressed throughout and sets off a short (sag.) occipital ring.

Pygidia certainly belonging to the species in account of the identical,
granulate ornamentation, somewhat wider than long, well rounded

46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

posteriorly. Axis narrow, tapered at moderate rate, defined by deep
axial furrows but barely rising above the general convexity of the
pygidium, composed of 6 rings plus a terminal unsegmented section,
reaching the border furrow. First ring with a strongly elevated
median node, all others lacking nodes. Pleural lobes very convex, un-
furrowed; border furrow relatively wide, setting off a flat border.
Surface with small, sparse granules. None of the specimens attain the
size of the holotype.

Occurrence.—The type locality is USNM 36b, near Greenwich,
Washington County, New York, where the associations of the species
are unknown. The writer was unable to find a limestone outcrop at
that location, possibly due to the rather vague indication “near School-
house No. 12” given by Walcott. The new material occurs in collec-
tion cs-26, Riders Mills, in association with Pagetides minutus and
other representatives of the Pagetides fauna.

Types.—Holotype: USNM 26710. Plesiotypes: USNM 156583.

CALODISCUS, species undetermined
Plate 3, figure 1

Known from a single, incomplete cephalon. The general structure
is much as in C. reticulatus, the glabella being divided by a transverse
furrow into posterior and anterior lobes. The anterior border is
strongly swollen medially, the border furrow merging with the axial
furrow. The convexity of the frontal border definitely distinguishes
this species from C. fissifrons, C. reticulatus, and C. theokritoffi, but
the condition of the specimen does not warrant a new name. Length
of cephalon 5 mm. Surface apparently smooth.

Occurrence.—Loose Lower Cambrian block cs-15/L1, in associa-
tion with a Pagetides faunule.

Disposition of material—Figured specimen: USNM 156582.

Genus CHELEDISCUS Rushton, 1966
Type species: Chelediscus acifer Rushton, 1966.
CHELEDISCUS CHATHAMENSIS, new species
Plate 3, figures 11-17

Available material—Several, more or less fragmentary cephala, and
two tentatively assigned pygidia, all in silicified condition.

Description——Glabella strongly tapered forward to a sharp point,
occupying about two-thirds of cephalic length, sloping down from a

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 47

highly elevated, rounded posterior portion to a low anterior end.
There is a broad, very shallow depression in front of the elevated
posterior part of the glabella. Glabella sloping vertically to occipital
furrow, but not concealing the occipital ring; the latter apparently
simple, of moderate length (sag.), but not well preserved in any of
the specimens. Genae strongly convex, laterally sloping vertically to
deep border furrow, divided in front by narrow, deep median furrow.
Frontal and lateral border of even width throughout, convex, down-
sloping, showing a series of faint radial impressions. Posterior border
furrow deep and wide, directed outward and forward, giving the
posterior border an elongate triangular shape. Posterior cephalic
margin with somewhat concave profile as the border is raised and
expanded backward toward the genal angle, where it extends into a
short spine. Beyond the spine the border slopes down to join the
lateral border. Length of largest cephalon 4.0 mm.

Pygidium, tentatively referred to the species on account of similarity
to the pygidium of C. acifer, also with strong relief. Axis relatively
wide, occupying most of pygidial length, strongly elevated above the
pleural regions, also convex in longitudinal profile, composed of 5
rings plus a terminal section. Ring furrows deep throughout ; at least
the anterior rings have an elevated median node. Pleural regions con-
vex and strongly downsloping, unfurrowed. Anterior and lateral
border furrow rather wide, moderately deep. Border narrow, ex-
tended downward into a vertical doublure. Length of larger pygidium
2.1 mm.

Surface of cephalon and pygidium densely covered with relatively
small granules.

Occurrence.—Collection cs-9a (Leptochilodiscus beds), Malden
Bridge.

Discussion —The first cephala were found associated with the
peculiar pygidium described herein as pygidium no. 7, and since the
granulate ornamentation appeared similar, the two parts were tenta-
tively referred to the same species. When later a few pygidia re-
sembling the pygidia of C. acifer (known from articulated, enrolled
specimens) were recovered, it became more plausible to combine these
pygidia with the cephalon of Chelediscus chathamensis. Nevertheless,
the writer does not feel entirely certain that this is the correct
assignment.

The cephalon of C. chathamensis, compared with C. acifer, has
much greater overall relief; the glabella is less tapered and does not
possess a definite transglabellar furrow. The border furrow is much

48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

deeper and the border more strongly convex. The tentatively assigned
pygidium differs from that of C. acifer mainly in the proportionately
narrower axis, deeper ring furrows, and greater width of border
furrow and border. The vertical doublure, which as shown by Rushton
(1966) in C. acifer fits inside the cephalic doublure like the lid into a
box, is present in both species.

Types: Holotype: USNM 156584. Paratypes: USNM 156585.

Genus LEPTOCHILODISCUS Rasetti, 1966
Type species : Leptochilodiscus punctulatus Rasetti, 1966.
LEPTOCHILODISCUS PUNCTULATUS Rasetti
Plate 1, figure 1; plate 3, figures 18-28

Leptochilodiscus punctulatus RASETTI, 1966a, p. 26, pl. 1, fig. 5; pl. 11, figs. 1-7.
Undetermined pygidium No. 1, Raserrt, 1966a, p. 38, pl. 11, figs. 17-21.

The species is rare at the type locality and the description of
Leptochilodiscus was based on the cephalon alone, suggesting that the
“undetermined pygidium No. 1” might belong to the species. This is
now proved correct by the close association of numerous specimens
at a new locality.

This better-preserved material shows a few features to be added
to the description. The posterior cephalic border has a sharp genicula-
tion near the distal end, where the margin is suddenly bent downward
and forward. A slender, not very long spine is an extension of the
posterior and lateral borders at the genal angle. New drawings of both
shields of the species are presented (pl. 1, fig. 1) in place of the in-
correct restoration of the cephalon previously published.

Several excellently preserved pygidia clearly show the small, down-
ward and rearward directed border spines. There are usually 8 pairs,
the posterior ones partially visible in dorsal view. The spines some-
what increase in length toward the rear, the longest ones being those
of the seventh and eighth pairs, which extend slightly beyond the
outline of the pygidium. In most of the specimens, dense pits cover
the surface of the genae and pleural regions; this ornamentation is
indistinct in some of the examples, especially those from the Pagetides
fauna.

One cephalon from Quebec, associated with Bolboparia canadensis,
is referred to the species and illustrated herein. The only difference
from the types is the slightly narrower lateral cephalic border. How-

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 49

ever, there is variation in this feature within the population from a
single bed.

Occurrence.—The types are from locality cs-4, Griswold farm. The
new material illustrated herein is from: Collection cs-9a, Malden
Bridge (discovered by A. R. Palmer) ; collection cs-29, in association
with a Pagetides faunule; and C. Hubert’s locality 63-F24, 4 mile
N. of Elgin Station, L’Islet County, Quebec (collected by G.
Theokritoff ).

Types.—Holotype: USNM 146009. Paratypes: USNM 146010-1.
Specimens described as “undetermined pygidium No. 1”: USNM
146033. Plesiotypes figured herein: USNM 156586-7; GSC 10565.

Genus OODISCUS Rasetti, 1966
Type species: Oodiscus subgranulatus Rasetti, 1966.
OODISCUS, species undetermined
Plate 5, figures 12-15

Pygidia referable to Oodiscus are exceedingly rare in association
with the Pagetides faunules. So far only four examples were re-
covered and are illustrated herein in order to present all the Eodiscidae
known from the assemblage. It is not certain that the four pygidia
belong to the same species, but this is a possibility.

The best-preserved of the pygidia is somewhat wider than long,
of low convexity, showing the subquadrate shape characteristic of the
genus. Axis tapered, showing but a trace of ring furrows, occupying
about two-thirds of the pygidial length. Pleural regions, border
furrow and border as in the type species. Surface of pleural regions
covered with scattered, rather large granules. Another pygidium
seems proportionately narrower and longer, but this may be the result
of distortion as the specimen is very poorly preserved. The third
specimen is very small and may belong to a different species as the
axis appears more sharply pointed, and the pygidial outline more
rounded ; this individual also seems to have a granulate surface. The
fourth pygidium has a slightly shorter axis and seems to lack
ornamentation.

Occurrence.—The specimens are respectively from collections cs-
3/L2, cs-15/L4, and cs-17/L1, loose Lower Cambrian blocks on the
Griswold farm ; and cs-18, Lopez farm, All were found in association
with Pagetides.

Disposition of material.—Figured specimens : USNM 156588-91.

50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

OODISCUS, species no. 1
Oodiscus, species undetermined No. 1, Rasetrtt, 1966a, p. 31, pl. 11, figs. 8-11.

This unnamed form was described on a few pygidia, possibly be-
longing to one of the species based on the cephalon. A single pygidium,
not illustrated herein as it would not supply additional information,
was collected from the Leptochilodiscus beds at the Malden Bridge
road cut (coll. cs-9a).

Genus SERRODISCUS R. and E. Richter, 1941

Type species: Eodiscus (Serrodiscus) serratus R. and E. Richter,
1941,

SERRODISCUS SPECIOSUS (Ford)
Plate 3, figure 29

Microdiscus speciosus Forn, 1873, p. 137, figs. 2a-b.

Eodiscus (Serrodiscus) speciosus (Ford) R. and E. Ricuter, 1941, p. 27, pl. 1,
figs. 15-21; pl. 4, fig. 61.

Serrodiscus speciosus (Ford) Rasettt, 1952, p. 444, pl. 52, figs. 1-11. Complete
synonymy to date.

Serrodiscus speciosus (Ford) Locuman, 1956, p. 1381, pl. 5, figs. 13-21.

The species is recorded for its stratigraphic importance as a typical
representative of the LElliptocephala asaphoides assemblage. An
articulated exoskeleton, flattened but otherwise well preserved in shale,
is figured.

Occurrence.—The figured specimen is from collection cs-24b in the
Judson Point section.

Types.—Plesiotype : USNM 156592.

SERRODISCUS SPINULOSUS Rasetti
Plate 1, figure 3; plate 4, figures 1-8
Serrodiscus spinulosus RASETTI, 1966a, p. 33, pl. 7, figs. 7-11.

This species, rare at the type locality, is one of the more common
trilobites in collection cs-9a at Malden Bridge. The new material
confirms the tentative previous assignment of the pygidium and shows
additional features.

Contrary to the previous statement, the posterior cephalic margin
at the geniculation shows the same articulating feature described
(Rasetti, 1966a) in Serrodiscus subclavatus. A short, narrow furrow
parallel to the posterior margin set off a low, narrow ridge which ex-
tends slightly beyond the straight outline of the margin.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI SI

The pygidial border has 8 pairs of blunt spines, visible in dorsal
view only as a slight waviness of the outline. The pygidial axis in
some specimens vaguely shows 6 rings, in others no trace whatever. In
most examples there is a small, horizontally directed spine on the sixth
ring. In one specimen, however (pl. 4, fig. 4), at this place there is
only a low node, even though the test is well preserved and a broken
spine would be conspicuous. The writer (Rasetti, 1966b) described
a similar variation in the pygidia of Pagetia billings.

Occurrence.—The type locality is cs-4, Griswold farm. Numerous
cephala and pygidia occur in collection cs-9a at the Malden Bridge
road cut. A fragmentary cephalon illustrated herein was recovered
from loose Lower Cambrian block cs-17/L1 on the Griswold farm in
association with a Pagetides-Pagetia faunule.

Types.—Holotype: USNM 146026. Paratypes: USNM 146027.
Plesiotypes figured herein: USNM 156593-4.

SERRODISCUS LATUS Rasetti
Plate 4, figures 9-12
Serrodiscus latus RAsETTI, 1966a, p. 34, pl. 10, figs. 12-15.

Available material—The species was based on the cephalon. Two
specimens of an associated pygidium in collection cs-9a are tentatively
referred to the species.

Description—Pygidium somewhat wider than long, with uniformly
curved lateral and posterior margin. Axis tapered, somewhat pointed
posteriorly, unfurrowed, almost reaching the border furrow. Pleural
lobes convex, unfurrowed but for the anterior border furrow which is
deeply impressed, and continues into a deep lateral and posterior
border furrow. Geniculation on anterior margin well marked, some-
what closer to axial furrow than to lateral angle. Border of uniform,
medium width, somewhat convex. Doublure apparently not extended
into spines ; however, the preservation is not adequate to ascertain this
feature. Surface smooth like the cephalon. Length of larger pygidium
2.4 mm, width 3.2 mm.

Discussion—The pygidium closely resembles the pygidium of
Litometopus longispinus, but seems to differ from example of that
species of similar size in the somewhat narrower and convex rather
than flat border. The cephala of the two species, aside from the spines
in Litometopus, are also rather similar. The present species partakes
of the features of Serrodiscus, Litometopus and Cobboldites.

Occurrence-—The type locality is cs-4, Griswold farm. The

52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 152

cephalon and pygidia illustrated herein are from collection cs-9a,
Malden Bridge.

Types.—Holotype; USNM 146024. Paratypes: USNM 146025.
Plesiotypes: USNM 156595.

SERRODISCUS GRISWOLDI, new species
Plate 4, figures 13-17

Available material—An imperfectly preserved cephalon and a
pygidium.

Description —Cephalon with strong relief. Glabella with undiffer-
entiated occipital ring slightly tapered, especially in anterior portion,
rounded in front, totally unfurrowed, defined by a deep axial furrow.
Genae rising somewhat above the axial furrow, strongly and about
uniformly convex, sloping down vertically to border furrow. Pre-
glabellar field convex, about one-eighth the glabellar length, lacking
any preglabellar depression. Border furrow deep and wide; border
rather narrow, strongly convex, showing 6 pairs of strong tubercles
giving the margin an irregular outline. Posterior cephalic border
and genal angle not preserved. Surface covered densely with small
granules, and more sparse spines of which only the broken base is
preserved. The ornamentation is identical with that observed in
species of Bolboparia. Length of cephalon 8.0 mm., width 8.6 mm.

Pygidium with strong relief, subtriangular. Axis strongly elevated,
defined by deep axial furrows, composed of 7 rings plus a short,
terminal section, occupying almost entire pygidial length. Ring fur-
rows very deep anteriorly, progressively shallower, until the last two
are only represented by short, shallow lateral impressions and are
totally effaced medially by the base of a strong spine, centered on
the seventh ring and presumably directed upward and backward,
broken off in the specimen. There are no nodes or spines on any
of the other rings. Pleural regions strongly convex, attaining vertical
slope laterally, overhanging the lateral and posterior parts of the
border furrow but not entirely concealing the lateral border in dorsal
view. Border furrow wide and unusually deep; border of medium
width, presumably narrower in posterior, not preserved portion, con-
vex, extended ventrally into relatively strong, widely spaced spines,
of which 5 pairs are preserved; from the spacing one may infer the
presence of a sixth pair. Anterior border deep and wide; geniculation
located slightly closer to axial furrow than to anterior angle of
pygidium, facet well developed. Surface of test, except in the furrows

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 53

and on the articulating half ring, which are smooth, identical with
that of cephalon. Length of pygidium 6.0 mm., width 7.0 mm.

Occurrence.—Collection cs-4 (Acimetopus bed), Griswold farm.

Discussion —Even though only one example of the cephalon and
one of the pygidium are known, reference of the two shields to one
species is suggested by the identical ornamentation, and by the num-
ber, spacing and size of the pygidial spines and the tubercles on the
cephalic border, which seem to match perfectly to allow a tight enroll-
ment of the exoskeleton. Among the other Eodiscidae from the
locality, the same type of ornamentation only occurs in Bolboparia,
and the matching of cephala and pygidia of that genus is well sub-
stantiated by association at three localities.

The species is markedly distinct from all forms of Serrodiscus
previously known. The strong convexity of the cephalon and the
narrow, tuberculate border show some similarity to S. subclavatus,
but the glabella is tapered rather than expanded in front. The
pygidium does not closely resemble that of S. subclavatus or any
other species. Its chief distinctive features are the unusually deep
axial and ring furrows, the latter being obsolete or shallow in most
of the other species of the genus, the small number of axial segments,
and the strong spine on the seventh ring. The spinose ornamentation
is not known in other species of Serrodiscus.

Types.—Holotype (cephalon) : USNM 156596, Paratype: USNM
156597.

Genus STIGMADISCUS Rasetti, 1966
Type species: Stigmadiscus stenometopus Rasetti, 1966.
STIGMADISCUS STENOMETOPUS Rasetti
Plate 1, figure 2; plate 5, figures 1-4

Stigmadiscus stenometopus RaseEttt, 1966a, p. 36, pl. 12, figs. 1-7.
Undetermined pygidium No, 4, RAsettt, 1966a, p. 46, pl. 6, figs. 20, 21.

The description of Stigmadiscus stenometopus was based exclu-
sively on the cephalon. A peculiar pygidium was described and
figured with the statement that it seemed unlikely that it could be
referred to any of the cephala in the collection. The recovery of
additional material showing further details now suggests the possi-
bility that this is the pygidium of the species,

All together, about 10 fragmentary specimens of the pygidium are
known. It would seem strange that no cephalic parts of such a large
trilobite had been recovered. On the other hand, the size and

54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

abundance would match the cephala of Stigmadiscus stenometopus.
Both cephalon and pygidium seemingly had a thinner test than the
other Eodiscidae in the collection, thus accounting for the usually
more fragmentary condition than it was observed in other genera
of the family.

The feature that is most suggestive of an Eodiscid, and could
only be observed in new material, is the presence of a series of
small, downward directed border spines, much as in Serrodiscus,
Acidiscus, Leptochilodiscus and other Eodiscid genera. If the pygid-
ium belongs to the Eodiscidae, the reference to Stigmadiscus becomes
virtually certain since all the other large cephala from the locality
already have a reliably assigned pygidium.

One pygidium preserves most of the axis and portions of the
pleural lobes. Together with the other specimens this allowed the
reconstruction of the entire pygidium. The first axial ring is nar-
rower medially than laterally, due to widening of the first ring furrow.
The rings 2-5 have their posterior margin extended medially into a
very short, horizontally directed spine accompanied by a slight median
inbend of the ring furrows. The seventh ring seemingly had a large
spine, broken off in the available specimens. The rings 8-13 lack
the short median spine, even though the inbend of the ring furrows is
still present. It is not certain whether the 13th ring is the last before
the terminal section or there are one or two more rings.

The pygidium showing the border spines is only preserved in its
anterior portion, where 5 spines are visible, one for each pleural
segment. Hence there were probably about a dozen pairs of spines
all together. The largest pygidium indicates a length of 14 mm.,
approximately agreeing with the size of the largest cephala.

Occurrence.—Described from locality cs-4, Griswold farm. A
few fragmentary cephala in collection cs-9a, Malden Bridge.

Types.—Holotype: USNM 146029. Paratypes: USNM 146030.
Specimens figured as “undetermined pygidium No. 4:’ USNM
146000. Plesiotype pygidia figured herein: USNM 156598.

Genus undetermined
Eodiscidae, cephalon no. 1
Plate 5, figure 11

Available material—An imperfectly preserved example.
Description.—Cephalon semicircular, moderately convex. Glabella
occupying slightly more than half the cephalic length, tapered, sloping

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 55

down toward the front, possibly with short lateral furrows. The
occipital ring seemingly was differentiated from the glabella, but
this part of the cephalon is incompletely preserved. Genae convex,
sloping down to a broad preglabellar depression medially. Border
furrow moderately impressed, border rather flat, of even width. The
posterior border may have been extended into a spine at the genal
angle. Surface lacking distinct ornamentation. Length of cephalon
1.9 mm., width 2.7 mm.

This cephalon differs from those of most Eodiscidae in the relatively
small glabella.

Occurrence.—Collection cs-9a (Leptochilodiscus beds) in the
Malden Bridge road cut.

Disposition of material—Figured specimen: USNM 156599.

Eodiscidae, cephalon no. 2
Plate 5, figures 5, 6

Available material—A somewhat incomplete, silicified example.

Description Cephalic outline representing about three-fourths of
an ellipse; maximum width somewhat behind the middle, slightly less
than the midlength. Glabella approximately parallel-sided in posterior
part, slightly constricted at midlength, somewhat expanded in front,
and tapering to a narrowly rounded point. In longitudinal profile the
glabella reaches maximum elevation just in front of the occipital fur-
row, where it extends into an upright spine; it is lowest at midlength,
where a broad, very shallow transglabellar depression occurs; the
frontal portion rises somewhat higher. Occipital ring short (sag.),
of uniform width, convex backward in outline, extending beyond the
outline of the genae. Genae convex all around the glabella, not
divided by a preglabellar depression; preglabellar field moderately
long. Border furrow well impressed; border relatively narrow, of
even width throughout, possibly extended into a short spine at the
genal angle. Posterior border short (tr.) on account of the narrowing
of the posterior part of the cephalon, straight. The only specimen
is incrusted with siliceous deposits that prevent observation of the
ornamentation, if any. Length of cephalon 2.9 mm.

Occurrence.—Collection cs-9a (Leptochilodiscus beds), Malden
Bridge.

Discussion.—This cephalon is unusual among the numerous Eodisci-
dae of the Acimetopus fauna in the outline narrowing toward the
genal angle, whereas almost all other cephala are widest at the

56 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

posterior end. The shape of the glabella is also distinctive, and the
convex, relatively long preglabellar field precludes reference to genera,
such as Calodiscus, which possess a preglabellar depression. Were
the species better known, it might form the basis for a new genus.
Disposition of material—Figured specimen: USNM 156600.

Eodiscidae, cephalon no. 3
Plate 5, figures 7, 8

Available material—A somewhat incomplete example.

Description—Cephalon approximately semielliptical, with some-
what flattened frontal outline. Glabella together with totally undif-
ferentiated occipital ring undefined from the genae, except posteriorly
where it extends beyond their posterior outline. On the left side of
the specimen there seems to be a portion of the axial furrow extending
for a short distance from the posterior margin, but this is believed
to be, at least to a large extent, a crack of the test caused by the
compaction of the sediment. Unfortunately on the other side this
part of the cephalon is not preserved. Genae convex both in trans-
verse and longitudinal profile. Frontal, lateral, and posterior border
furrow and border well developed. Border relatively narrow, of even
width throughout. The posterior border furrow and border curve
slightly forward distally. The border at the genal angle is not pre-
served; the portion of posterior border preserved does not show a
sharp geniculation. Surface smooth. Length of cephalon 4 mm.

Occurrence.—Collection cs-29, W. of the Griswold farm, in asso-
ciation with Pagetides elegans, P. minutus, Pagetia laevis, and Lepto-
chilodiscus punctulatus. The first three species are typical of the
Pagetides fauna, whereas Leptochilodiscus, known in that assemblage
only from this locality, is a holdover from the older Acimetopus
fauna.

Discussion —This peculiar cephalon should possibly be referred
to Weymouthia, the only genus of Eodiscidae of North America
with an undifferentiated glabella. The genus is poorly known; the
only specimen definitely referable to the species, the holotype of
Weymouthia nobilis (Ford), was lost soon after its description and
is only known from Ford’s illustration ; and furthermore, the posterior
part of the cephalon of the specimen was stated to be missing. The
general shape of the cephalon described herein agrees with Ford’s
figure, except in lacking the tubercles on the border. Owing to the
difficulty of assessing the affinities of such almost featureless cephala,

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 57

and the imperfect knowledge of Weymouthia, it is deemed preferable
to refer the present form to an undetermined genus.
Disposition of material—Figured specimen: USNM 156601.

Eodiscidae, cephalon no. 4
Plate 5, figures 9, 10

Available material—A single, poorly preserved example.

Description.—Cephalon semielliptical, of moderate convexity. Gla-
bella not greatly elevated, defined by a moderately deep dorsal furrow,
on the average tapered forward, divided by a broad, shallow trans-
verse furrow into two lobes. Anterior lobe narrow, somewhat pointed
in front; posterior lobe wider, seemingly elevated posteriorly, possibly
into a spine. Occipital ring not preserved. Cheeks moderately convex,
the convexity increasing toward the margin, divided by a very shallow,
median furrow connecting the axial and border furrows. Border
furrow and border both narrow but well defined, neither being
preserved in the posterior half of the cephalon. The border seem-
ingly possessed a pair of short spines at the approximate level of the
anterior third of the cephalon, but too little of this feature is preserved
to allow a positive statement. Test apparently smooth, but too poorly
preserved to show a fine ornamentation, if any. Length of cephalon
3.5 mm., width 4.0 mm.

Occurrence.—Collection cs-9a (Leptochilodiscus beds), Malden
Bridge.

Discussion.—The glabella has the same features as in Analox
bipunctata, but otherwise the cephalon is quite different from that
species in possessing an anterior and lateral border of even width and
a median preglabellar furrow. No satisfactory generic reference
can be suggested.

Disposition of material—Figured specimen: USNM 156602.

Eodiscidae, pygidium no. 5
Plate 4, figures 22, 23

Available material—An incomplete example.

Description—Pygidium proportionately long and narrow, tapered
toward the rear. Axis preserved only in posterior part, slightly
tapered, moderately raised above the pleural region, almost reaching
the border furrow, seemingly unfurrowed. Pleural regions unfur-
rowed, almost flat over most of their area, but sloping down steeply
in the median portion on each side. Anterior border furrow gradually
curving into the lateral border furrow, which becomes shallower

58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

toward the rear but is distinct throughout. Anterior border wide,
with well-developed facet; lateral border narrow, extended into
several pairs of blunt, very short spines not visible in dorsal view.
Posterior portion of the border again wider. A pair of strong spines,
seemingly long judging by the moderate rate of tapering near the
base, and directed horizontally backward and slightly outward, appear
as extensions of the border at the posterolateral angles of the
pygidium. Surface smooth. Length of pygidium 5.6 mm., width
4.3 mm.

Occurrence.—Loose Lower Cambrian block cs-3/L3, Griswold
farm, in association with a Pagetides faunule.

Discussion.—No generic reference can be suggested in the absence
of a cephalon. This pygidium differs from any described among the
Eodiscidae in the presence of a pair of large posterolateral spines.

Disposition of material—Figured specimen: USNM 156603.

Eodiscidae, pygidium no. 6
Plate 4, figure 21

Available material—A poorly preserved example.

Description—Pygidium fairly convex, tapered toward the rear.
Axis tapered, straight-sided, well defined by the axial furrow but
not raising greatly above the pleural regions, long but not reaching
the border furrow. Traces of numerous ring furrows visible on
coated specimen. Pleural regions very convex laterally, sloping down
to border that almost certainly was developed all around the pygidium.
Only the wide, straight anterior border and a portion of very narrow
posterolateral border are preserved. Pleural regions unfurrowed
aside from the anterior border furrow. A pair of large, closely spaced
spines, directed backward and slightly curving inward, arise from the
border. Surface too poorly preserved to detect a fine ornamentation,
if any. Length of pygidium 2.5 mm., width 2.4 mm.

Occurrence.—Loose Lower Cambrian block cs-17/L1, in associa-
tion with a Pagetides faunule.

Discussion.—This pygidium has in common with the preceding
the presence of a pair of posterior border spines, which in the present
form are more closely spaced. In all other observable features, the
pygidium recalls Leptochilodiscus punctulatus, differing from that
species in the great development of one of the pairs of marginal
spines and the narrower axis. However, no definite generic reference
can be made in the absence of the cephalon.

Disposition of material—Figured specimen: USNM 156604.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 59

Eodiscidae, pygidium no. 7
Plate 4, figures 18-20

Available material—Two specimens, of which one is well preserved,
in silicified condition.

Description—Pygidium semielliptical with very strong relief. Axis
strongly elevated, about a third the pygidial width, parallel-sided,
rounded posteriorly, not quite reaching the border furrow. Articu-
lating furrow and two ring furrows well impressed across the axis;
a third ring furrow shallower. The terminal section is extended into
a strong spine, at the base almost as wide as the axis itself, sloping
upward at a low angle, in one of the pygidia somewhat curving
downward, in the other almost straight, fully as long as the remainder
of the pygidium. Anterior pygidial border set off by deep border
furrow, and showing well-developed facet. One pleural furrow,
narrow but deep, is almost parallel to anterior border furrow and is
uniformly impressed from axial furrow to border furrow; there is
no trace of other pairs of furrows. Border furrow moderately deep
and wide; border of even width, with very narrow doublure, lacking
spines.

Pygidium covered with small granules. Length of pygidium exclu-
sive of spine, 2.4 mm., with spine 4.7 mm., width 2.8 mm.

Occurrence.—Collection cs-9a (Leptochilodiscus bed), Malden
Bridge.

Discussion—Two features characterize this pygidium, the exceed-
ingly strong, terminal axial spine and the presence of one, relatively
deep pair of pleural furrows. In the discussion of Chelediscus
chathamensis it was mentioned that reference of this pygidium to
that species cannot be excluded. It seems more likely, however, that
it belongs to an unknown cephalon. To avoid nomenclatural confu-
sion, the policy of not proposing taxa of the Eodiscidae on the basis
of pygidia is applied to this case, even though the pygidium may be
different enough from known forms to justify a separate genus.

Disposition of material_—Figured specimens: USNM 156605.

Family PAGETIIDAE Kobayashi, 1935

Genus PAGETIA Walcott, 1916

Type species: Pagetia bootes Walcott.

The Lower Cambrian strata of Columbia County yielded copious
material of two species of Pagetia which are quite different from
P. connexa (Walcott), occurring at several localities in the Taconic

60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

sequence of Washington County. No specimens of the latter were
found in Columbia County. The Middle Cambrian strata yielded
two species, closely related to forms of the western United States.

PAGETIA BIGRANULOSA, new species
Plate 7, figures 1-9

Available material—Large numbers of cranidia and pygidia.

Description—Glabella tapered, narrowly rounded in front, indis-
tinctly furrowed. Occipital furrow well impressed laterally ; posterior
part of glabella and occipital ring jointly extended into a horizontal,
rapidly tapered spine. Preglabellar field on average shorter (sag.)
than border, forming a shallow depression where the axial and border
furrows merge. Palpebral area convex, somewhat upsloping proxi-
mally but slightly down-sloping distally, about as wide as glabella.
Ocular ridges not marked; palpebral furrow deep, straight, directed
longitudinally ; palpebral lobe somewhat wider at midlength, almost
a third the glabellar length. Anterior border rather wide (sag.)
medially, somewhat tapered at the sides, slightly convex, with broad,
shallow radial markings. Posterior border furrow deep from axial
furrow to facial suture. At the inner, posterior angle of the genae
formed by the axial and border furrows is a slight, poorly defined,
subtriangular elevation set off by a very shallow, oblique furrow.
Examination of Middle Cambrian material shows that a similar fea-
ture, although more effaced, is visible at least in some specimens of
most forms of Pagetia. The writer (Rasetti, 1966b) failed to mention
this characteristic, which in the present species and the next is par-
ticularly well marked.

Pygidial axis strongly elevated, overhanging posterior border fur-
row, barely tapered, showing 3 or 4 rings defined by increasingly
shallow furrows plus a terminal section extended into a slender,
somewhat upward-directed spine. Moderately elevated nodes appear
on the first 2 or 3 rings. Pleural regions showing 3 or 4 pairs of
pleural furrows (including the anterior border furrow) and very
narrow, shallower interpleural furrows. Border furrow shallow,
border narrow.

Surface of test covered with dense, excessively fine granules visible
only on perfectly preserved material under thin coating of magnesium
oxide, plus large, but not greatly elevated granules well developed on
glabella, genae, and the ribs between the pleural furrows in the
pygidium. Length of largest cranidium, exclusive of spine, 1.9 mm.,

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 61

the average being about 1.5 mm. Pygidia averaging about 1.4 mm.
in length.

Occurrence.—Holotype from loose block cs-17/L1; also in blocks
cs-3/L2, cs-3/L3, all on the Griswold farm. Found in bedded rocks in
collections cs-15 and cs-29, north and west of the Griswold farm.
In association with Lower Cambrian Pagetides faunules.

Discussion.—The species is markedly distinct from all previously
described, chiefly in the depth and straight course of the palpebral
furrow, wider palpebral lobe, pleural and interpleural furrows on
the pygidium, and characteristic ornamentation. The palpebral lobes
are rather like in Pagetides than Pagetia, but other features, such as
the anterior border with well-developed radial impressions, and the
pygidial spine, are indicative of Pagetia. The species does not
resemble P. connexa (Walcott) from approximately contemporaneous
(Rasetti and Theokritoff, 1967) Lower Cambrian strata in Wash-
ington County. The latter species resembles the Middle Cambrian
forms in the features mentioned above.

Types.—Holotype: USNM 156606. Paratypes: USNM 156607-9.

PAGETIA LAEVIS, new species
Plate 7, figures 10-16

Available material—Numerous cranidia and a lesser number of
pygidia.

Description.—It it unnecessary to give a complete description, as
the species appears almost identical with the preceding, except in
the ornamentation. This consists only of exceedingly fine, often
indistinct granules, the large granules being absent. The pleural
furrows on the pygidium may be somewhat less deeply impressed than
in P. bigranulosa, but this character varies within a population and
does not seem of specific importance. Length of largest cranidium,
exclusive of spine, 2.0 mm.

Occurrence.—The type locality is cs-26, near Riders Mills, where
P. bigranulosa seems absent. Also in loose blocks cs-3/L2, cs-3L/3
on the Griswold farm, and in collection cs-29 from bedded rock, in
association with the preceding species.

Types.—Holotype: USNM 156610. Paratypes: USNM 156611-2.

PAGETIA ERRATICA, new species
Plate 13, figures 1-7

Available material—Numerous cranidia and pygidia.
Description.—Glabella slightly tapered, narrowly rounded in front,

62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

occupying (without spine) about two-thirds the cranidial length.
Lateral furrows faint to indistinct; occipital furrow deep laterally ;
occipital ring and glabella drawn into a long, horizontal spine. Pre-
glabellar field about twice the sagittal length of border, with shallow
medial depression. Palpebral area upsloping, slightly convex, appre-
ciably wider than the glabella when the palpebral lobe is included.
Ocular ridges curved, faintly visible. Palpebral lobe narrow and
long, relatively well defined by a palpebral furrow which fades out
both in front and back of the palpebral lobe without reaching the
facial sutures. Anterior border relatively narrow, of constant width
from midline to facial suture, set off by a shallow but distinct border
furrow, horizontal, slightly concave in profile, with usual radial mark-
ings. Posterior border deep. In some of the specimens an exceedingly
fine granulation is observable. Length of largest cranidium, exclusive
of spine, 1.7 mm.

Pygidial axis strongly elevated, showing 4 rings plus a terminal
section separated by deep ring furrows; each ring provided with a
strongly elevated node, the terminal section extended into the usual
spine, broken off in the specimens. Pleural regions with very shallow
furrows fading out distally; border furrow wide and moderately
impressed, border narrow. Surface densely covered with very fine
granules. Length of pygidium, exclusive of spine, 1.4 mm.

Occurrence.—Loose blocks cs-7/M4 (type locality), cs-7/M3, cs-
7/M5, cs-7/M7, Griswold farm, in association with trilobites of the
Bathyuriscus-Elrathina zone.

Discussion.—This species shares with P. rugosa Rasetti (1966b)
the relatively small glabella, long preglabellar field, and distinct pal-
pebral furrows. However, the anterior border is slighty concave and
better defined on the inner side by the border furrow, and the orna-
mentation is much weaker. Other species with which P. erratica
may be compared are P. fossula Resser and P. clytia Walcott (Rasetti,
1966b). Neither of them, however, has a well-developed palpebral
furrow, the border in either species is slightly convex rather than
concave and tapers in width at the sides, and the glabella is larger
in proportion to the entire cranidium. The pygidium closely re-
sembles that of P. fossula. The last species is from the Lakeview
Limestone of Idaho, referable to the Bathyuriscus-Elrathina zone.
P. erratica does not closely resemble any of the species previously
known from eastern North America.

Types.—Holotype: USNM 156613. Paratypes: USNM 156614.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 63

PAGETIA CLYTIOIDES, new species
Plate 13, figures 8-16

Available material—About two dozen specimens, mostly cranidia.

Description.—Glabella almost parallel-sided, well rounded in front.
Lateral furrows very shallow to indistinct ; occipital furrow impressed
laterally ; posterior part of glabella and occipital ring extended into
long, horizontal spine. Preglabellar field with broad, shallow depres-
sion, on average of equal sagittal length as the border. Ocular ridges
indistinct; palpebral area upsloping and slightly convex; palpebral
furrow and lobe as in preceding species. Anterior border flat, defined
by a shallow, broad border furrow, of approximately even width or
slightly narrowed laterally, with usual radial markings.

Pygidium with elevated axis showing 3 rings plus a terminal sec-
tion. Rings with moderately elevated nodes; terminal section ex-
tended into slender spine generally broken off. Pleural regions show-
ing but traces of pleural furrows. Border furrow fairly wide, border
narrow. Surface of test seemingly smooth. Length of largest cra-
nidium, exclusive of spine, 1.6 mm., length of largest pygidium
1.3 mm.

Occurrence.—Collection cs-6, Griswold farm (Bathyuriscus-El-
rathina zone). A few, small specimens in collection cs-9c are tenta-
tively referred to the species.

Discussion—This species is somewhat intermediate between P.
erratica and P. clytia Walcott (Rasetti, 1966b). It differs from P.
erratica chiefly in the less rapidly tapered, more rounded glabella,
greater proportional length of glabella relative to the cranidium and
consequently shorter preglabellar field, and less distinct pleural fur-
rows on the pygidium. All these differences appear significantly
statistically, but variability within a population is such that it might
not be easy to classify a single specimen, especially an immature one.
P. clytioides is almost identical with P. clytia in the general propor-
tions of the various parts, the chief differences being the less tapered
and more rounded glabella and especially the better developed pal-
pebral furrow.

Types.—Holotype: USNM 156615. Paratypes: USNM 156616-7.

Genus PAGETIDES Rasetti, 1945

Types species: Pagetides elegans Rasetti, 1945.
Species of Pagetides are among the most common trilobites in the
Lower Cambrian limestones of Columbia County. Specimens closely

64 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I52

matching the types of all 5 species described by the writer from the
conglomerate boulders of the lower St. Lawrence valley were ob-
tained. However, partly owing to intraspecific variability, partly to
the imperfect preservation and immature condition of much of the
material, not all the cranidia or pygidia could be unambiguously
classified. Pagetides elegans can always be clearly separated. P.
amplifrons and P. rupestris could be separated in the Quebec material,
but they are very similar and, especially in the case of isolated cranidia,
difficult to distinguish. Another pair of similar species are P. minutus
and P. leiopygus. In the original material the cranidia were virtually
indistinguishable, the two species being separated by association with
quite different pygidia, those of leiopygus almost lacking axial and
ring furrow. In the Columbia County material only a few pygidia of
leiopygus were identified, whereas copious cranidia and associated
pygidia of minutus occur at several localities.

Pygidia of all species of Pagetides possess pleural furrows when
immature.

PAGETIDES ELEGANS Rasetti
Plate 5, figures 16-24

Pagetides elegans Rasettt, 1945, p. 313, pl. 1, figs. 15-18; 1948a, p. 11, pl. 1,
figs. 1-7.

This is among the most common trilobites in the Pagetides fauna.
Specimens from the Taconic sequence match the types from Quebec
except in usually showing pronounced nodes on the axial rings. Since
species of Pagetia and Pagetides frequently show variation in this
feature, even among individuals from one stratum, specific separa-
tion is not warranted. A cranidium and pygidium from the Quebec
boulders are illustrated for comparison.

Occurrence.—Found in place in collections cs-4b, cs-5, cs-26, cs-29,
and in several loose Lower Cambrian blocks (see fossil lists).

Types.—Plesiotypes figured herein: USNM 156618-20.

PAGETIDES MINUTUS Rasetti
Plate 6, figures 1-10

Pagetides minutus Rasettt, 1945, p. 313, pl. 1, figs. 11, 12; 1948a, p. 12, pl. 1,
figs. 13, 14,

This is also one of the more common species of the genus. In the
area investigated it first appears in slightly lower beds than P. elegans,
already occurring in association with Neopagetina, and is present in

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 65

all strata carrying the Pagetides fauna. A cranidium and pygidium
from the Quebec boulders are figured for comparison.
Occurrence.—Found in place in collections cs-4a, cs-4b, cs-18, cs-
20, cs-26, and in several loose Lower Cambrian boulders (see fossil
lists).
Types.—Plesiotypes figured herein: USNM 156621-5.

PAGETIDES LEIOPYGUS Rasetti
Plate 6, figures 11-14

Pagetides leiopygus Rasetti, 1945, p. 314, pl. 1, figs. 7-10; 1948a, p. 12, pl. 1,
figs. 10-12.

A few pygidia approaching in smoothness the type material were
recovered. Since they occurred in association with far more copious
pygidia of P. minutus, no attempt was made to identify cranidia of
the species. Topotypes from Quebec are illustrated for comparison.

Occurrence.—The figured pygidia occur in collection cs-3/L2, loose
Lower Cambrian block on Griswold farm.

Types.—Plesiotypes figured herein: USNM 156626-8.

PAGETIDES RUPESTRIS Rasetti
Plate 5, figures 25-29
Pagetides rupestris Rasettt, 1948a, p. 12, pl. 1, figs. 15-21.

This species is moderately common in the Pagetides fauna in Co-
lumbia County. Usually the cranidia can be readily distinguished,
unless they are very small, in which case they may be confused with
P. minutus. Pygidia are more difficult to distinguish from the latter
species, especially when immature. Topotypes from Quebec are
figured for comparison.

Occurrence.—Found in place in collections cs-4c, cs-5, and in sev-
eral loose Lower Cambrian blocks on the Griswold farm.

Types.—Plesiotypes figured herein: USNM 156629-31.

PAGETIDES AMPLIFRONS Rasetti
Plate 6, figures 15-18

Pagetides amplifrons Rasettt, 1945, p. 314, pl. 1, figs. 1-6; 1948a, p. 12, pl. 1,
figs. 8, 9.
A few cranidia are tentatively referred to the species rather than
P. rupestris on the basis of the proportionately narrower, longer shape
and the less upright attitude of the occipital spine.

66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Occurrence.—Collections cs-4b and cs-15/L1, Griswold farm.
Types.—Plesiotypes figured herein: USNM 156632-3.

Genus NEOPAGETINA Pokrovskaya in Tchernysheva, 1960

Types species.—Pagetina rjonsnitzkii Lermontova, 1940.

The writer (Rasetti, 1966b) pointed out that only the type species
should be left in the genus, other forms described by Lermontova
(1951) and Lazarenko (1962) appearing more typical of Pagetia.
Neopagetina seems to differ from Pagetides mainly in the presence
of pleural furrows, hardly a feature of generic significance, especially
in view of the fact that pygidia of Pagetides (see P. minutus figured
herein, pl. 6) have furrows in immature stages. However, there may be
more important differences in unknown characters (e.g., the number
of thoracic segments), hence the writer refrains from proposing that
Neopagetina be considered a subjective junior synonym of Pagetides.

NEOPAGETINA TACONICA, new species
Plate 6, figures 20-28

Available material—Numerous cranidia and a lesser number of
pygidia.

Description.—Glabella, exclusive of spine, about two-thirds as long
as cranidium, sloping down anteriorly, somewhat pointed in front,
showing two pairs of broad, shallow, short furrows at the sides.
Glabella extended into a thick, upsloping spine. Occipital ring distinct
at the sides, medially merging with the rearward glabellar extension ;
occipital furrow impressed at the sides in the form of a pair of broad
pits. Cheeks convex, highest posteriorly, sloping down anteriorly,
divided by a narrow, shallow preglabellar depression. Palpebral lobes
somewhat in advance of the glabellar midpoint, widest at their mid-
point, defined by a well-impressed palpebral furrow; distance from
posterior end of palpebral lobe to posterior margin somewhat greater
than length of palpebral lobe. Facial sutures as in Pagetia and Page-
tides. Border furrow broad and shallow, medially merging with the
preglabellar depression. Anterior border slightly raised, rather flat,
slightly wider medially ; posterior border set off by deep furrow, which
turns forward and extends to posterior branch of facial suture; genal
angle fairly sharp but not extended into spine.

Pygidium 1.5 times wider than long. Axis defined by deep axial
furrow, slightly tapered, almost reaching posterior border furrow,
composed of 5 or 6 rings plus a terminal section. Nodes of decreasing

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 67

elevation occur on the first 4 rings. Pleural regions convex and down-
sloping, with 5 pairs of pleural furrows in addition to the anterior
border furrow; traces of interpleural furrows visible in some of the
specimens. Border furrow shallow, moderately wide; border very
narrow. Surface of test smooth. Length of largest cephalon 2.0 mm.,
of pygidium 1.5 mm.

Occurrence——Lower Cambrian. Collections cs-9 (type locality),
road cut near Malden Bridge ; cs-4a, Griswold farm ; and cs-20, Lopez
farm.

Discussion—Comparing with the illustrations of Neopagetina
rjonsnitzkit published by Lermontova (1951) and Pokrovskaya (in
Tchernysheva, 1960) the present species seems to differ in the better-
defined palpebral lobes, lack of ocular ridges, more transverse py-
gidium, and broader, shallower pleural furrows. The cephalon might
also be compared with Pagetides elegans, which it resembles in the
proportions of the various parts. In the latter species the preglabellar
depression is broader, the anterior border convex and more definitely
expanded medially, the genal angle more widely rounded, and the
glabellar furrows are almost indistinct.

Types.—Holotype: USNM 156634. Paratypes: USNM 156635-6.

Genus HEBEDISCUS Whitehouse, 1936
Type species: Ptychoparia attleborensis Shaler and Foerste, 1888.
HEBEDISCUS MARGINATUS, new species
Plate 6, figure 19

Available material—One cranidium.

Description —Glabella prominent, especially elevated in posterior
portion, unfurrowed, extended together with occipital ring into a
strong, upsloping spine of unknown length. There is an indication
of the occipital furrow as a pair of lateral impressions. Genae with
moderate relief. Frontal area flat, about a third as long (sag.) as
glabella. A broad, shallow depression, medially confluent with the
axial furrow, should presumably be interpreted as the border furrow
by comparison with other species of the genus. However, the border
so defined shows a narrow, shallow furrow paralleling the anterior
cranidial margin and setting off a narrow rim. Palpebral area some-
what convex and upsloping; ocular ridges visible, directed outward
from axial furrow and curving slightly backward. Palpebral lobes con-
spicuous, set off by a deep palpebral furrow, wider in posterior part,
convex transversely, about a third the length of glabella excluding

68 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

the occipital ring. Anterior branch of facial suture directed forward
and outward; posterior branch directed backward, and also somewhat
downward and outward. Posterior border furrow deep; posterior
border forming sharp posterolateral angle. Surface of test smooth.
Length of holotype cranidium with incomplete spine 2.3 mm.

Occurrence.—Collections cs-51, limestone lens in black shale about
one mile E. of Salme, Washington County, New York. In association
with Calodiscus lobatus, Elliptocephala asaphoides, Fordaspis nana,
Serrodiscus speciosus.

Discussion—The general shape of the cranidium agrees with
Hebediscus, but the present form differs from all described species
in several important features, chiefly the strong occipital spine, deep
palpebral furrow with well-differentiated palpebral lobe, and the
unusual frontal rim. The palpebral lobe is like in Neocobboldia, but
other features are more suggestive of Hebediscus.

Types——Holotype: USNM 156637.

Order OLENELLIDA
Family OLENELLIDAE Vogdes, 1893

Olenellid fragments are common in the Acimetopus and Pagetides
faunas. However, the overwhelming majority of their delicate tests
were reduced to fragments too small even for generic identification.
The few reasonably complete cephala in the collections are immature,
generally 3-6 mm. in length. No attempt at identification with de-
scribed species was made, since the latter were usually based on large
specimens, often characterized by features of the entire exoskeleton.
Nevertheless, the immature specimens show specific characteristics
that allow comparison with individuals similarly preserved from
other localities. No new taxa are proposed herein, Species of Ole-
nellus and Paedeumias are labeled by a number, the same number
being used for species described in a previous paper (Rasetti, 1966a).

Genus PAEDEUMIAS Walcott, 1910
Type species: Paedeumias transitans Walcott, 1910.
PAEDEUMIAS, species no. 1
Plate 8, figures 11-14, 18
Paedeumias, species undetermined no. 1, RAsEtTTI; 1966a, p. 40, pl. 12, figs. 23-25.

Several well-preserved cephala were collected, none exceeding 3.3

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 69

mm. in length. Some show the characteristic features better than the
original material.

Occurrence.—Collection cs-9a (Acimetopus bilobatus faunule) near
Malden Bridge. Also in loose block cs-15/L3 north of the Griswold
farm.

Disposition of material—Figured specimens: USNM 156639-40.

PAEDEUMIAS, species no. 2
Plate 8, figures 6-8
Paedeumias, species undetermined no, 2, RAsETTI, 1966a, p. 41, pl. 12, figs. 19, 20.

Unfortunately even in the new material only the glabella and
palpebral lobes are preserved. A relatively large glabella, 5 mm. in
length inclusive of the occipital ring, shows a weak ornamentation in
fingerprint pattern. The species is chiefly characterized by the narrow-
ness of the frontal glabellar lobe and the well-defined, narrow rim
around the palpebral lobes.

Occurrence.—Collection cs-9a (Acimetopus bilobatus faunule) near
Malden bridge. Also loose block cs-15/L3 north of the Griswold
farm.

Disposition of material—Figured specimens: USNM 156641-2.

PAEDEUMIAS, species no. 3
Plate 8, figure 15

Available material—A complete cephalon.

Description —Glabella approximately parallel-sided, with frontal
lobe as wide as the posterior portion. Glabellar furrows straight,
transverse, fairly deep, extended for a third the glabellar width.
Occipital ring as long (sag.) as the glabellar lobes; there may have
been a small spine at its posterior margin. Portion of the genae
comprised between glabella and palpebral lobe narrow, at its widest
not exceeding one sixth the glabellar width. Palpebral lobe moder-
ately elevated, widest medially and tapered at both ends, with a
definite rim set off by a narrow furrow; rim width about a third the
width of palpebral lobe. Preglabellar field of average length (sag.)
for the genus, with a faint median ridge. Cephalic border very nar-
row, convex, defined by a shallow furrow. Intergenal spine very
small, located at somewhat less than half the distance from axial
furrow to genal angle, appearing as the extension of a ridge originat-
ing at the posterior end of palpebral lobe. Genal spine short and
slender, appearing as extension of the lateral border. Posterior

7O SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

cranidial margin between intergenal and genal spines directed out-
ward and slightly forward. Surface smooth. Length of cephalon
2.8 mm.

Occurrence.—Collection cs-9a near Malden Bridge.

Discussion.—This form differs from species no. 1 in several fea-
tures, chiefly the narrower area between glabella and palpebral lobe,
better defined rim of palpebral lobe, narrower cephalic border, and
different position and size of the intergenal spine.

Disposition of material_—Figured specimen: USNM 156643.

PAEDEUMIAS, species no. 4
Plate 8, figure 18

Available material.—A single, fragmentary cephalon.

Description.—Glabella approximately parallel-sided, with frontal
lobe approximately as wide as the others. Glabellar furrows of first
pair meeting across the glabella; second pair interrupted medially,
transverse in direction. Furrows of third pair curving inward and
backward. Occipital furrow similar to third glabellar furrow, con-
sisting of deeper lateral portions convex forward, barely joined medi-
ally. Occipital ring not enough well preserved to determine if it
bore a spine. Area of the genae inside palpebral lobe narrow. Palpe-
bral lobe about uniformly wide, one-third of the width consisting of
rim, set off by a well-impressed furrow. Other parts not preserved.

Occurrence.—Collection cs-9a near Malden Bridge.

Discussion—This form resembles species no. 2 in the relatively
wide glabella, narrow inner portion of cheek, and strongly rimmed
palpebral lobe. It differs chiefly in the greater width of the frontal
glabellar lobe.

Disposition of material—Figured specimen: USNM 156644.

PAEDEUMIAS, species no. 5
Plate 8, figures 19-21

Available material—Several, almost complete cephala.

Description —Glabella relatively narrow, parallel-sided, with frontal
lobe as wide as the others. Glabellar lobation as in species no. 1 but
for a slight expansion of the second glabellar lobe. Inner area of
genae about half as wide as glabella. Palpebral lobes wide, with in-
definite rim, Preglabellar field of average length for the genus, with
faint median ridge. Border wirelike, very narrow. Genal spine short,
not advanced in position. Intergenal spine stronger and longer than

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 71

genal spine and very close to it, appearing as extension of ridge
originating as posterior end of palpebral lobes. Genae showing vague
coeca; no other ornamentation present. Length of largest cephalon
5 mm.

Occurrence.—Loose blocks cs-15/L2 and cs-15/L5, north of Gris-
wold farm, in association with a Pagetides faunule.

Discussion—tThe glabellar shape and lobation indicate close rela-
tionship with species nos. 1 and 3. The present form agrees with
species no. 3 in the narrow border, but the position of the intergenal
spine is like in species no. 1. The latter, however, has a much wider
border.

Disposition of material—Figured specimens: USNM 156645

PAEDEUMIAS, species no. 6
Plate 8, figures 16, 17

Available material—Two fragmentary cephala.

Description.—Glabella proportionately wide, very slightly tapered.
Glabellar furrows deep, fairly straight, crossing somewhat more than
a third of the glabellar width, directed inward and slightly backward,
the first pair joined through a shallower, rearward-inbent median
portion. Occipital ring similar to glabellar lobes, seemingly bearing
a median spine at posterior margin. Palpebral lobes seemingly rather
narrow, of even width, lacking rim, unless the latter is broken off.
Inner portion of genae at its midpoint somewhat narrower than half
the glabellar width. Other portions of cephalon not preserved.

Occurrence-—Loose block cs-15/L3, associated with Paedeumias
species nos. 1 and 4 and with Analox bipunctata, hence seemingly
with the Acimetopus faunule.

Discussion.—The glabellar lobation and width of the inner portion
of the cheeks are similar to species nos. 1 and 5, but the glabellar
lobes are proportionately wider (tr.) and shorter (sag.). The width
of the inner portion of the cheeks separates this form from Paedeu-
mias species nos. 2 and 4, and also the lack of a palpebral rim, if this
is really a feature of the present species.

Disposition of material—Figured specimens: USNM 156646,

Genus OLENELLUS Billings, 1861
Type species: Olenus thompsoni Hall, 1859.
OLENELLUS, species no. 1

Plate 8, figures 1-4
Olenellus, species undetermined, RAsetti, 1966a, p. 42, pl. 12, figs. 21, 22.

72 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Additional material allows a complete description of the cephalon.
The distance from the glabella to the anterior cephalic margin is
somewhat less than the length of the frontal glabellar lobe. There is
no preglabellar field, the very shallow border furrow merging with
the axial furrow in front of the glabella. The border is exceptionally
wide, flat, barely down-sloping near the margin. The genal angle is
extended into a short, somewhat outward-directed spine. A much
longer intergenal spine is located somewhat closer to the genal angle
than to the axial furrow, and appears as the extension of a ridge
originating at the posterior end of the palpebral lobe and crossing
the posterior border.

Resser and Howell (1938) described several species of Olenellus
with wide border, but not quite as wide as in the present form.

Occurrence.—The original material was from collection cs-4, Gris-
wold farm. The examples illustrated herein are from loose block
cs-15/L3, which seems to represent equivalent beds.

Disposition of material—Figured specimens: USNM 156647.

OLENELLUS, species no. 2
Plate 8, figures 9, 10

Available material—A few specimens, preserving only the glabella
and palpebral lobes.

Description.—This species, as far as known, is almost identical
with the preceding, hence it is sufficient to point out the differences.
The main distinguishing feature is the lack of an upright spine in the
occipital furrow. There seems to be, instead, a small spine at the
posterior margin of the occipital ring. The first glabellar furrow
has a more definite median inbend. A faint rim is visible on the
palpebral lobes on one of the specimens. The largest glabella has
a length of 3.6 mm. inclusive of occipital ring.

Occurrence.—Collection cs-9a (Leptochilodiscus bed) at the
Malden Bridge road cut, and loose block cs-15/L2, in association with
Paedeumias species no. 5 and a Pagetides faunule.

Disposition of material—Figured specimens: USNM 156648-9.

OLENELLUS, species no. 3

Plate 8, figure 5

Available material—A fragmentary cephalon.
Description.—Frontal glabellar lobe not preserved ; furrow between
frontal and second lobe impressed at the sides, directed backward

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 73

and inward. Second glabellar lobe expanded laterally, following for
a considerable distance the boundary of the palpebral lobe, separated
from the inner cheek by a furrow running outward and forward.
The second lobe hence envelopes the third lobe, from which it is
clearly separated by a furrow only at the sides. Third lobe narrowest
(tr.) of all, tapering forward. Fourth lobe wider (tr.), also some-
what tapered forward. Occipital furrow well marked at the sides,
very shallow medially. Occipital ring much like the fourth glabellar
lobe, bearing a small spine at posterior margin. Entire glabella not
greatly elevated. Palpebral lobe long, almost reaching the level of
posterior margin of occipital ring, wide, lacking distinct rim. Surface
rather indistinctly granulate and wrinkled. Presumed length of gla-
bella with occipital ring, if complete, 5.5 mm.

Occurrence.—Loose block cs-15/L5.

Discussion —tThe reference to Olenellus rather than Paedeumias is
rather arbitrary, owing to lack of the external parts of the cephalon,
and was chiefly suggested by the similarity to the 2 preceding species
of Olenellus in the glabellar lobation. In the present form the gla-
bellar furrows are shallower, the second glabellar lobe envelopes the
third lobe more distinctly, the posterior lobes definitely taper forward,
and there is no indication of a palpebral rim.

Disposition of material—Figured specimen: USNM 146650.

Order undetermined

The Agnostida, Eodiscida, and Olenellida form natural and readily
recognizable orders of trilobites, but, in the writer’s opinion, no satis-
factory classifications of the remainder of the Cambrian trilobites
have been proposed. Several of the orders and suborders that have
been suggested seem to have little phylogenetic basis and suffer from
lack of sharp discriminating characters. In many cases, therefore,
the assignment of a family or genus to one or the other of these pro-
posed orders or suborders is more or less arbitrary.

These views were expressed by the writer (Rasetti, 1948a), and
the classifications proposed since that time have not substantially
altered his conclusions. Therefore, no taxa above the superfamily
level are used. The trilobites of the Lower and Middle Cambrian
strata discussed herein, other than the forms included in the three
preceding orders, are referred to the superfamilies Corynexochacea
(corresponding to the order Corynexochida of the Treatise on In-
vertebrate Paleontology), Paradoxidacea, and Ptychopariacea (in-
cluding at least a large part of the suborder Ptychopariina of the

74 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

order Ptychopariida of the Treatise). In the Treatise the suborder
Ptychopariina was split into a large number of superfamilies, mostly
lacking either phylogenetic basis or diagnostic features.

Superfamily CORY NEXOCHACEA Angelin, 1854
Family CORYNEXOCHIDAE Angelin, 1854
Genus CORYNEXOCHIDES Rasetti, 1948

Type species: Corynexochides gregarius Rasetti, 1948.
CORYNEXOCHIDES ? EXPANSUS, new species
Plate 12, figure 1-17

Available material—Numerous protaspides, meraspid cranidia, a
few holaspid cranidia, hypostomes, and tentatively assigned pygidia.

Description—The following description applies to the holaspid
cranidium. Glabella narrow and parallel-sided in posterior half, ex-
panded to twice the width in anterior portion, rounded in front,
reaching anterior cephalic margin. Two posteriormost pairs of lateral
furrows moderately deep at the sides, connecting through a shallow
median portion; two other pairs of furrows short, appearing as shal-
low indentations of the glabellar side. Occipital furrow well im-
pressed, deeper laterally ; occipital ring extended into moderately long
spine. Palpebral area wider than the posterior portion of glabella;
palpebral lobes narrow, short, somewhat obliquely situated, at level of
glabellar midpoint. Ocular ridges faint but distinct. Fixigenae
anterior to ocular ridges present only at the sides, where a slightly
raised border is developed. Posterior area large, triangular, twice as
wide (tr.) as posterior portion of glabella, apparently extended into
short, broad spine at genal angle as in meraspid cranidia. Furrow on
posterior area deep and straight. Surface of test with low granules,
more pronounced on fixigenae. Length of largest cranidium 3.0 mm.

Hypostome referred to the species of the general corynexochoid
shape, mainly characterized by the great forward expansion of the
anterior lobe. Anterior wings, representing the fused rostrum, form-
ing on each side a straight, oblique outline. Median lobe narrow,
defined anteriorly by a very shallow, transverse furrow, posteriorly
by a pair of furrows deep at the sides, shallow medially, forming a
semicircle concave toward the front. Posterior lobe with a pair of
short lateral spines and a narrow posterolateral border. Terrace lines
evident on anterior lobe and anterior wings. Length of largest hypo-
stome 1.8 mm.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 75

Ontogeny.—The earliest known stage is the metaprotaspis, which is
relatively large for so small a trilobite. Glabella parallel-sided for
most of its length, about a tenth the width of the shield, well defined
by the axial furrow, expanding anteriorly to 3 times the posterior
width, reaching the frontal margin. Three pairs of shallow furrows,
plus the occipital furrow, impressed across the glabella. Occipital ring
prominent. There is a pair of deep pits at the anterior corners of the
glabella.

Frontal ridge tapering laterally and disappearing. Transverse con-
vexity pronounced, especially at midlength, where the test is deeply
downfolded. Posteriorly the convexity decreases, the margin being
slightly raised and provided with a faint but distinct border ending
in a blunt tooth that marks the posterolateral angle of the proto-
cranidium. The protopygidium is bent downward vertically with re-
spect to the protocranidium; its axis consists of a first ring in form
of a round knob, and a second one barely distinguishable. The pleural
regions are slightly concave, rather than convex, transversely. Length
of average protaspis in dorsal view, 0.65 mm.

Meraspid cranidia in earlier stages not larger, or even smaller,
than the corresponding portion of the protaspis, the smallest being
0.55 mm. long. Glabella with occipital ring, frontal ridges, and an-
terior pits as in protaspis. Small, anteriorly situated palpebral lobes
are increasingly conspicuous in successive stages. The faint border at
the posterolateral angles of the protocranidium gradually extends
into a short, blunt spine; however, in the absence of free cheeks one
cannot infer from this structure that the course of the facial suture
is proparian. Changes in later stages are mainly the expansion of the
glabella involving a greater portion of its length, but becoming corre-
spondingly less sudden; the deepening of the glabellar furrows at the
sides ; the development of the occipital spine ; the ocular ridge becom-
ing gradually distinct from the marginal ridge; and the greater pro-
portional length and elevation of the palpebral lobes. A cranidium
0.75 mm. long has already acquired most of the features of the
holaspis.

Small pygidia that are common in association with the other parts
are referred to the species because of their resemblance to the pro-
topygidium of the protaspis. These pygidia vary little in structure
and size, the average being 0.5 mm. long and 0.9 mm. wide, of sub-
quadrate shape. Axis prominent, composed of 2 rings plus a terminal
section, each ring preserving some of the globular appearance of
the first ring of the protopygidium. Anterior margin of pygidium

76 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 152

straight, transverse, anterior angles sharp. Pleural lobes unfurrowed,
slightly concave transversely, almost lacking longitudinal convexity.
Lateral margin straight, extended posteriorly into a short spine. Pos-
terior margin almost straight between the pair of shallow notches on
the inner side of this spine. These pygidia presumably are meraspid
transitory pygidia.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion. A few small cranidia in collection cs-23.

Discussion.—The cranidium of this species resembles to some ex-
tent Corynexochides latifrons Rasetti (1948b) differing mainly in
the more slender glabella, more anterior position of the palpebral
lobes, larger and more triangular posterior area. These differences,
plus the failure to find in association with the cranidia any pygidium
resembling Corynexochides and, instead, the probable assignment to
the species of an entirely different pygidium, make the reference to
the genus unsatisfactory. However, no better assignment to described
genera occurred to the writer. Were the holaspid pygidium definitely
known, the best course would be to propose a new genus. The pres-
ent species occurs in much younger beds than the described species
of Corynexochides.

Types.—Holotype: USNM 156651. Paratypes: USNM 156652-3.

Family DOLICHOMETOPIDAE Walcott, 1916
Genus BATHYURISCUS Meek, 1873
Type species: Bathyurus (?) heydeni Meek, 1873.
BATHYURISCUS EBORACENSIS, new species
Plate 11, figures 1-14

Available material—Entire immature cranidia, fragmentary larger
cranidia, a few free cheeks, hypostomes, and several well-preserved
pygidia.

Description—Glabella in larger cranidia narrowing forward in
posterior third, then expanding forward. Four pairs of lateral fur-
rows visible; first three pairs exceedingly shallow, transverse; pos-
terior pair deep, directed inward and strongly backward, at posterior
end turning inward but not quite joining across the glabella. Occipital
furrow well impressed ; occipital ring bearing a spine. Anterior fixi-
genae expanding forward, the anterior facial suture diverging at about
45 degrees; border not well differentated, upturned, much reduced
but not vanishing medially. Palpebral lobe narrow, strongly curved,
well defined by palpebral furrow; palpebral area elevated in posterior

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 77

part near the axial furrow, as in many related dolichometopid trilo-
bites. Posterior area not completely preserved in any of the larger
cranidia, slender as usual in the genus. Elevated parts of cranidium
finely granulate. Length of largest cranidium about 5 mm. Small,
presumably meraspid cranidia with glabella more definitely expanded
forward, palpebral lobes more obliquely directed, hence distant from
axial furrow at rear end, and posterior area broader, less extended
beyond the palpebral lobe than in the larger cranidia. Free cheek
relatively flat, with poorly defined border furrow and border, and
short, tapered genal spine. Among a few types of corynexochoid
hypostomes present in the collection, shape and frequency of occur-
rence suggest that the one figured herein be tentatively referred to
the species. Its most chracteristic feature is a shallow, median depres-
sion a short distance from the anterior margin.

Among thoracic segments present in the collection, some are tenta-
tively attributed to the species, since they seem to be too common and
too large to be referred to any other species. The pleurae end in
spines, longer than usually observed in species of the genus.

Pygidium with elevated, slightly conical axis showing generally 6
well-defined rings plus a terminal section, extended into a short post-
axial ridge reaching the border furrow. Pleural regions almost hori-
zontal, with vaguely defined border furrow and very narrow border.
Seven pairs of broad pleural furrows and as many pairs of inter-
pleural furrows, very narrow near the axial furrow and broadening
distally, are all well impressed almost to the pygidial margin. Pygidia
about 1.7 times wider than long, apparently increasing in propor-
tional length with size; length of largest pygidium 4 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion. Very fragmentary material in collection cs-23, Judson Point, is
tentatively referred to the species.

Discussion.—This species appears closest to Bathyuriscus fimbri-
atus Robison (1964a) from the lower part of the Bolaspidella zone of
Utah. As far as can be determined from the smaller and partly
fragmentary specimens available, the present species appears to differ
in the stronger divergence of the anterior facial sutures, broader basal
part of the glabella, and deeper posterior pair of glabellar furrows.
The pygidia have very similar structure and pattern of the pleural
and interpleural furrows, but those of the present species are propor-
tionately shorter and wider. Since Robison has shown that the rela-
tive length increases with the size of the pygidia, the last difference
may be partly due to the less mature examples available.

Types.—Holotype: USNM 156654. Paratypes: USNM 156655-6.

78 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

BATHYURISCUS, species undetermined
Plate 12, figures 29-31

Available material—A fragmentary cranidium and a fragmentary
pygidium, plus a complete pygidium from a different locality pre-
sumably representing the same species.

Description—Glabella expanding in anterior portion, showing two
shallow, broad pairs of lateral furrows. Occipital furrow shallow,
occipital ring expanded medially but seemingly rounded. Anterior
fixegenae only partly preserved, fairly wide even at anterior end of
palpebral lobe, expanding forward. Palpebral lobe fairly straight in
anterior portion, curved in posterior part, set off by broad palpebral
furrow; palpebral area flat. Posterior area broadly furrowed, very
slender, parallel-sided except near end where the facial suture curves
backward to cut posterior margin, very long (tr.), the portion outside
of palpebral lobe longer than inner portion. Surface seemingly smooth.
Length of cranidium 5.5 mm.

Pygidium twice broader than long, with outline regularly curved
but for a slight median notch. Axis well tapered, showing 5 rings
separated by narrow furrows, plus a terminal section, almost reach-
ing the border furrow. Pleural region with faint convexity, shallow
border furrow, and flat, fairly wide border. Five pairs of shallow,
broad pleural furrows and 4 pairs of shallow interpleural furrows,
very narrow proximally and broadening distally, all end in the shallow
border furrow. Opposite the first 3 axial rings there is on each pleura
a low, wedge-shaped ridge dividing each pleural furrow in its proximal
part. This is a frequent feature in corynexochoid trilobites (e.g., well
developed in Zacanthoides). Length of complete pygidium 2.7 mm.,
width 5.3 mm.

Occurrence.—The cranidium and portion of a pygidium are from
collection cs-9d*, Malden Bridge. The complete pygidium from loose
block cs-7/M1, Griswold farm. At both localities in association with
Ptychagnostus gibbus and other trilobites of the Bathyuriscus-El-
rathina zone.

Discussion—The material is too incomplete to allow a significant
comparison with described species. The pygidium seems almost identi-
cal with the pygidia of small examples of Bathyuriscus rotundatus
(Rominger) from the Ogygopsis shale of British Columbia. The
cranidium seemingly has longer palpebral lobes and more slender
posterior area.

Disposition of material—Figured specimens: USNM 156657-8.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 79

Genus ATHABASKIELLA Kobayashi, 1942
Type species: Bathyuriscus (Poliella) probus Walcott, 1916.
ATHABASKIELLA, species undetermined
Plate 11, figures 15, 16

Available material_—Several pygidia.

Description —Pygidial axis about equally wide and long, strongly
elevated, about half the pygidial length, rounded posteriorly, extended
into a narrow postaxial ridge. One axial ring distinct, the remainder
unsegmented or at most with a shallow furrow visible at the sides.
Pleural regions down-sloping near axis, somewhat concave; anterior
angles widely rounded. Two shallow pairs of pleural and one or two
pairs of interpleural furrows visible, all curving backward and tend-
ing to become parallel to the margin; border furrow and border
indistinct. Length of largest pygidium 1.7 mm., width 2.4 mm.

Occurrence.—Collection cs-21 (Bosaspidella zone), Stockport
Station.

Discussion.—This pygidium does not significantly differ from the
type species ; however, owing to the immature material and lack of a
cranidium, specific identification is not attempted.

Disposition of material—Figured specimens: USNM 156660.

Genus BATHYURISCIDELLA Rasetti, 1948
Type species: Bathyuriscidella socialis Rasetti, 1948.
BATHYURISCIDELLA, species undetermined
Plate 11, figures 17, 18

Available material—One pygidium.

Description.—Axis short and broad, strongly elevated, concave in
longitudinal profile, raised into a knob at posterior end, followed by
postaxial ridge, One ring furrow well impressed at the sides, a second
one very shallow. Pleural platforms down-sloping; 3 pairs of rather
shallow pleural furrows, and 2 pairs of equally shallow and narrower
interpleural furrows are visible, all ending in a shallow border furrow.
Border rather flat, wider laterally, almost disappearing medially on
account of the postaxial ridge, bearing a pair of short spines some
distance back of the anterior angles. Surface of pleural platforms
finely granulate. Length of pygidium 1.9 mm., width 3.6 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport
Station.

80 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Discussion.—This pygidium has the unmistakable structure char-
acteristic of the genus. It differs from B. socialis in the more definitely
concave profile of the axis, presence of 1 rather than 2 well-defined
ring furrows, pleural and interpleural furrows fairly parallel to each
other, and granulate rather than smooth surface of the pleural regions.

Disposition of material—Figured specimen: USNM 156659.

Genus HEMIRHODON Raymond, 1937
Type species: Hemirhodon viator Raymond, 1937.
HEMIRHODON, species undetermined

Plate 11, figure 19

Available material—A few fragmentary pygidia.

Description —FPygidial axis not greatly elevated, about two-thirds
the pygidial length, consisting of 3 rings plus a terminal section, sepa-
rated by shallow furrows. Pleural regions slightly convex proximally,
becoming concave near the margin, lacking well-defined border fur-
row and border. Four pairs of broad, shallow pleural furrows and 3
pairs of narrower interpleural furrows are visible, all ending in the
poorly defined border furrow. Length of largest pygidium 2.8 mm.,
width 4.5 mm.

Occurrence.—Collection cs-21, Stockport Station.

Discussion.—The pygidium is fully typical of the genus, but spe-
cific identification cannot be attempted with the material in hand.

Disposition of material—Figured specimen: USNM 156661.

Family ZACANTHOIDIDAE Swinnerton, 1915
Genus ZACANTHOIDES Walcott, 1888
Type species: Zacanthoides romingert Resser, 1942.
ZACANTHOIDES, species undetermined
Plate 10, figure 34

A single cranidium is fully typical of the genus. Glabella almost
parallel-sided, slightly expanded in frontal portion. Three pairs of
shallow lateral furrows; occipital furrow well impressed, occipital
ring expanded medially, presumably spinose. Palpebral area and lobe
partly preserved, of typical structure. Anterior fixigenae expanded
laterally due to the divergent course of the facial suture. Border
poorly differentiated from preglabellar field. Length of cranidium
7 mm.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 81

The proportions of the cranidum are about the same as in Z. ro-
mingert, but the glabellar furrows appear to be shallower.

Occurrence——Loose block cs-7/M3, in association with Pagetia
erratica and other trilobites of the Bathyuriscus-Elrathina zone.

Disposition of material—Figured specimen. USNM 156662.

Genus PROZACANTHOIDES Resser, 1937
Type species: Olenoides stissingensis Dwight, 1889.
PROZACANTHOIDES, species undetermined
Plate 7, figures 19-22

Available material—Several cranidia and pygidia from different
outcrops or boulders, generally immature and not well preserved. It
is not certain that this material represents one species.

Description.—Glabella expanded forward in anterior half, parallel-
sided in posterior portion. Glabellar furrows very shallow; occipital
furrow distinct, occipital ring bearing a spine. Preglabellar field short
(sag.), border elevated. Anterior fixigenae expanded laterally on
account of divergence of anterior facial sutures. Palpebral area flat ;
palpebral lobe as usual in the genus, fairly straight in anterior portion,
curved in medial part; posterior end of palpebral lobe considerably
distant from axial furrow. Posterior area not preserved in any of
the specimens.

Pygidia with strongly elevated, relatively short and wide axis show-
ing at least one ring plus a terminal section. Anterior outline of
pleural regions widely rounded. Pleural furrows wide and shallow,
curving backward; 2 pairs of interpleural furrows very shallow and
narrow. Border differentiated only by lack of furrows, extended into
3 or 4 pairs of short, backward-directed spines.

Occurrence.—The figured specimens are from collections cs-4, cs-
3/L2, and cs-26, For other occurrences see faunal lists by localities.
Prozacanthoides was only found in the Lower Cambrian Pagetides
faunules.

Discussion—The specimens are typical of Prozacanthoides but
their poor preservation and immature character preclude any attempt
at specific identification. Furthermore, most of the named species
were based on very few examples, hence one cannot evaluate the
variability within a population and the validity of these species. A
form of this genus from the Taconic sequence was described by
Walcott (1891) under the name Zacanthoides eatoni, The type lo-
cality is USNM 43a, near Salem, Washington County, New York.

82 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Also specimens collected at locality USNM 38a, near North Granville,
were referred by Walcott to the species. The holotype is a relatively
well-preserved cranidium, similar to the specimens collected in Co-
lumbia County. The associations of Prozacanthoides eatoni (Wal-
cott) indicate that the species is a member of the Pagetides fauna
(Rasetti and Theokritoff, 1967). It is possible that at least part of
the material from Columbia County is conspecific with Walcott’s type,
but neither is known well enough for a positive identification.
Disposition of material_—Figured specimens: USNM 156663-5.

Family DORYPYGIDAE Kobayashi, 1935

The family is mainly represented in the collections from the Lower
Cambrian beds of the Taconic sequence by species of Bonnia, which
in the Columbia County localities occur both with the Acimetopus and
Pagetides faunules. These trilobites are not common, and usually
only fragmentary pygidia, specifically unidentifiable and contributing
nothing to the knowledge of the genus, were recovered. This material
was not deemed worth illustrating ; however, the presence of Bonnia
in the various collections was reported in the faunal lists.

Genus KOOTENIA Walcott, 1888
Type species: Bathyuriscus (Kootenia) dawsoni Walcott, 1888.
KOOTENIA, species no. 1
Plate 12, figures 18-21

Available material—Several, poorly preserved cranidia and pygidia,
mostly lacking the test.

Description.—Glabella somewhat expanded forward, with but traces
of lateral furrows. Occipital furrow well impressed, occipital ring
apparently spinose. Only fragments of other cranidial parts preserved.

Pygidia better preserved than the cranidia. Axis slightly tapered,
showing 4 rings plus a terminal section; on exfoliated material one
more ring furrow may be visible. Four pairs of pleural furrows (in-
cluding the anterior border furrow) wide, shallow on outer surface,
fairly deep on internal impressions. Traces of the interpleural fur-
rows are visible on the proximal part of the pleural regions. Border
furrow shallow; border flat, relatively wide. Marginal spines short,
rapidly tapered, rather flat; there are 6 pairs, with spacing gradually
decreasing toward the rear. Surface of test smooth. Length of
cranidium 3 mm., of largest pygidium 4 mm.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 83

Occurrence.—Collection cs-9d*, Malden Bridge (Bathyuriscus-
Elrathina zone).

Discussion.—This form is typical of the 6-spined group of species
which are the most common in the Middle Cambrian. It closely
resembles K. elongata Rasetti (1948b) but has shorter marginal
spines, and K. ellsi (Walcott) (Rasetti, 1948b), which has short
spines but a proportionately longer and narrower pygidium. The
material is inadequate for specific identification.

Disposition of material_—Figured specimens: USNM 156666.

KOOTENIA, species no. 2
Plate 6, figure 32

Available material—One incomplete pygidium.

Description.—Pygidial axis with at least 7 segments, presumably
plus a terminal section. The few rings preserved do not show nodes.
Pleural regions of moderate convexity, showing 6 pairs of pleural
furrows (inclusive of the anterior border furrow), all about equally
and uniformly impressed from the axial furrow to the border. Traces
of interpleural furrows are visible near the axial furrow. Border
furrow and border barely differentiated. Margin extended into a
series of evenly spaced, slender, backward-directed spines of un-
known length. Owing to the fragmentary condition of the specimen,
the number of spines cannot be determined with certainty, but there
were at least 6 pairs and the most likely number is 7. Surface of
test indistinctly granulate.

Occurrence-—Lower Cambrian Pagetides faunule at locality cs-26.

Discussion—This form resembles Kootenia marcoui (Whitfield)
from the Parker Shale of Vermont, which has 7 pairs of marginal
spines. There are 3 species of Kootenia previously known from the
Taconic sequence. Kootenia troyensis Resser, recently redescribed
and illustrated by Lochman, greatly differs from all other known
species in the subtriangular pygidium, great relief of the axis, and
vertical slope of the marginal portion of the pleural regions. The
cranidium is also distinctive in the vertical slope of the genae an-
terior to the ocular ridges. Excellent material was recently collected
in Washington County by R. Metz, in association with Calodiscus
lobatus, Serrodiscus speciosus, and Elliptocephala asaphoides. A
second, unnamed species, described by the writer (Rasetti, 1966a)
as a member of the Acimetopus bilobatus faunule, shows no resem-
blance to the form discussed herein. The third species of Kootenia

84 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

described from the Lower Cambrian of the Taconic sequence is
K. fordi (Walcott). Of the two illustrated cotypes, the cranidium
(Walcott, 1891, pl. 94, fig. 3) is from USNM locality 38c. Addi-
tional material from this locality in the U. S. National Museum
shows that both the cranidia and pygidia are identical with Kootenia
troyensis and occur with an Elliptocephala asaphoides assemblage.
The cotype pygidium (Walcott, 1891, pl. 94, fig. 3a) is from USNM
locality 38a, and the same collection in the Museum includes cranidia,
hypostomes, and pygidia of the species. This form is associated
with a Pagetia connexa faunule. Hence the cotype cranidium and
pygidium belong to different species, from different localities and
of different ages. Walcott’s pygidium is hereby selected as lectotype
to avoid discarding the name troyensis as a junior synonym and
proposing a new name for the species occurring with Pagetia connexa.
Kootenia fordi, as now defined by the selection of the lectotype, is
quite different from the species described herein in the smaller
number of segments both in the axis and pleural regions.
Disposition of material—Figured specimen: USNM 156667.

Genus OLENOIDES Meek, 1877
Type species: Paradoxides nevadensis Meek, 1877
OLENOIDES STOCKPORTENSIS, new species
Plate 11, figure 23

Available material—One pygidium.

Description.—Pygidial axis not greatly elevated, tapered, composed
of 4 distinct rings plus a terminal section, extended into a very short
postaxial ridge. Pleural regions with 3 pairs of well-impressed pleural
furrows and as many interpleural furrows, all fading out at the
position of the indistinct border furrow. The first pleural furrow
slightly converges toward the following interpleural furrow distally,
pleural and interpleural furrows of the other 2 pairs are about
parallel to each other. Indefinite pygidial border extended into 4 pairs
of strong, long spines of slightly decreasing spacing toward the rear,
the distance between the spines of the fourth pair being the smallest,
less than the thickness of the spines at the base. Spines of first pair
somewhat more slender and probably shorter than others, directed
outward and backward; spines of second pair stronger and longer,
directed more definitely backward; spines of third and fourth pairs
directed straight backward. Each spine of the second to fourth pair
has a protuberance on the outer side near the base. Length of

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 85

pygidium exclusive of spines, 2.6 mm., width 4.7 mm. Surface of
test finely and rather indistinctly granulate.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion—The writer in general considers it poor taxonomic
practice to propose a species on a single specimen, especially a pygid-
ium. Here, however, the differences from all described species are
striking enough to allow identification from one individual. Main
characteristic features are the presence of only 3 pairs of pleural
and interpleural furrows, and especially the size, direction, and
peculiar structure of the marginal spines.

Types.—Holotype: USNM 156668.

OLENOIDES, species undetermined
Plate 11, figures 20-22

Available material—One holaspid and a few meraspid pygidia.

Description.—Holaspid pygidium with long, slightly tapered axis
occupying most of pygidial length, extended into a postaxial ridge
that crosses the border furrow reaching the margin. Axis composed
of 4 distinct rings plus a terminal, unsegmented section. Pleural
regions rather flat, with a broad, shallow border furrow and a flat,
fairly wide border. Four pairs of broad, shallow pleural furrows
and 3 pairs of equally shallow, narrower interpleural furrows im-
pressed. First furrow somewhat converging toward next interpleural
furrow distally, pleural and interpleural furrows of second and third
pairs almost parallel to each other, furrow of fourth pair very close
and parallel to axis, leaving no space for a fourth interpleural fur-
row. Border extended into 4 pairs of marginal spines, all directed
more or less backward; those of first pair slightly outward, those
of last two pairs slightly inward, and tapering at faster rate than
the others. Surface of test smooth.

Transitory meraspid pygidia similar to holaspid except in having
an extra segment that will become part of the thorax. Length of
holaspid pygidium, exclusive of spines, 2.7 mm., width 5.4 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion.—This form is typical of the 4-spined group of Ole-
noides. The pattern of the pleural furrows and the spacing of the
marginal spines seem somewhat intermediate between those observed
in O. curticei Walcott from the Conasauga Shale of Alabama and
O. rasettii Ivshin (1957) [pro Olenoides convexus Rasetti, 1948,

86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

non Olenoides convexus Lermontova, 1940]. Too little is known of
the present form to attempt specific identification.
Disposition of material—Figured specimens: USNM 156669.

Genus undetermined
Dorypygidae, cranidium no. 1
Plate 6, figures 29, 30

Available material—A few cranidia, possibly representing the
same species.

Description—Glabella in largest specimen expanding forward,
about 14 times wider at anterior than at posterior end. Four pairs
of glabellar furrows visible, the fourth pair fairly deep laterally
and connecting medially through a shallower portion. Occipital
furrow well impressed, occipital ring apparently extended into a
short spine. Apparently there is no frontal area; anterior fixigenae
only developed at the sides, not entirely preserved. Palpebral lobes
relatively small, somewhat more than a fourth the glabellar length;
palpebral area about half as wide as glabella. Other portions of
cranidium not preserved. Surface smooth. Length of largest cranid-
ium 2.9 mm.

A cranidium 1.5 mm. long, tentatively attributed to the same
species, differs in the much more strongly and abruptly expanded
glabella, longer palpebral lobes, and palpebral area at least as wide
as the posterior part of the glabella.

Occurrence.—Loose block cs-15/L1, Griswold farm, in association
with the Lower Cambrian Pagetides fauna.

Discussion.—The generic reference of these cranidia is uncertain
in the absence of a pygidium, since a number of corynexochoid
genera are almost indistinguishable from the cranidia, especially in
immature stages. Similar forms from Lower Cambrian strata were
referred to Dolichometopsis(?) by Rasetti (1948a) and a new genus
Bonnaria by Lochman (1956), included in the family Dorypygidae
and considered a close relative of Bonnia. The writer has observed
that the features supposed to characterize Bonnaria are found in
immature specimens of Bonnia, e.g., undescribed material of Bonnia
bicensis Resser. Since the holotype of Bonnaria salemensis (Resser)
is a cranidium only 2.2 mm. long, most of the other examples at-
tributed to the species by Lochman are still smaller, and the pygidium
is unknown, the basis for the genus seems questionable. Seemingly
many of the corynexochoid trilobites of the families Dorypygidae,

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 87

Corynexochidae, and Dolichometopidae possess a suddenly expanded
glabella in immature stages.
Disposition of material—Figured specimens: USNM 156670.

Family OGYGOPSIDAE Rasetti, 1951
Genus OGYGOPSIS Walcott, 1889
Type species: Ogygia klotzi Rominger, 1887.
OGYGOPSIS, species undetermined
Plate 10, figure 32

Available material—One pygidium.

Description—Pygidium somewhat less than twice wider than long,
approximately semicircular. Axis straight-sided, moderately tapered,
reaching the border furrow, showing 9 or 10 rings, the last few
somewhat indistinct. About eight pairs of pleural furrows, almost
straight and uniformly impressed from axial furrow to border.
Interpleural furrows very shallow, visible only in distal part of
pleurae. Border furrow very shallow, border flat, moderately wide.
Length of pygidium 2.7 mm., width 4.7 mm.

Occurrence.—Loose block cs-7/M3, in association with Pagetia
erratica and other trilobites of the Bathyuriscus-Elrathina zone.

Discussion.—This pygidium resembles Ogygopsis more than other
described genera, but the reference cannot be considered certain.
The main difference from described species is in the wider and
shorter proportions.

Disposition of material —Figured specimen: USNM 156671.

Family ORYCTOCEPHALIDAE Beecher, 1897
Genus ORYCTOCEPHALUS Walcott, 1886
Type species: Oryctocephalus primus Walcott, 1886
ORYCTOCEPHALUS, species undetermined
Plate 10, figure 33

A single, very small cranidium agrees in all respects with Orycto-
cephalus but is inadequate for specific identification. Glabella some-
what expanded in the middle. Posterior glabellar furrows a pair of
pits connected across the glabella; other two pairs represented by
unconnected pits. Occipital furrow well impressed, occipital ring
narrower (tr.) than glabella, widened medially. Palpebral area,
palpebral lobe, ocular ridges, and border as in typical forms of the
genus, Length of cranidium 1 mm.

88 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Occurrence.—Collection cs-6 (Bathyuriscus-Elrathina zone), Gris-
wold farm,
Disposition of material—Figured specimen: USNM 156672.

Family undetermined
Genus PROTYPUS Walcott, 1886
Type species: Angelina hitchcocki Whitfield, 1884
PROTYPUS, species undetermined
Plate 6, figure 31

A single, immature cranidium seems definitely referable to the
genus. The specimen differs in no observable features from Protypus
marginatus Rasetti (1948a), which is a rather variable species. All
the features of the specimen are shown by the illustration. Length
of cranidium 2.0 mm.

Occurrence.—Loose block cs-3/L2, Griswold farm (Pagetides
fauna).

Disposition of material—Figured specimen: USNM 156673.

Genus undetermined
Corynexochacea, pygidium no. 1
Plate 12, figures 22, 23

Available material—Three well-preserved examples.

Description—Pygidium subelliptical, about twice wider than long,
of moderate convexity. Axis tapered, extended into a short post-
axial ridge that reaches the posterior margin. About 4 rings plus
a terminal section, defined by very shallow furrows, are distinguish-
able. Pleural platforms with moderate convexity, sloping down to
a broad, undefined border furrow and flat border. Three pairs of
broad, well-impressed pleural furrows and as many pairs of very
shallow, narrow, interpleural furrows are impressed, the pleural
furrows cutting somewhat obliquely across each pleura. Pygidial
margin with one pair of very short, obtuse spines extending from the
first pleura and a trace of a second, more posterior pair. Surface of
test smooth. Length of largest pygidium 1.6 mm., width 3.0 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion.— This pygidium resembles to some extent the pygidia
of Olenoides, but lacks the strong marginal spines of that genus; it

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 89

also somewhat resembles the pygidia of Athabaskia, Bathyuriscus,
and related genera. More precise identification is not possible without
an associated cranidium.

Disposition of material—Figured specimens: USNM 156674.

Corynexochacea, pygidium no. 2
Plate 14, figure 14

Available material—One incomplete example.

Description—Pygidium approximately semicircular, of low con-
vexity. Axis not completely preserved, moderately tapered, seemingly
composed of 4 rings plus a terminal section separated by shallow
furrows, not reaching the posterior margin. Pleural lobes almost
flat, with vaguely defined border furrow and border. Four pairs
of pleural furrows and 3 pairs of interpleural furrows all about
equally impressed; the anterior border furrow curves backward
distally, almost paralleling the rounded anterior angle of the pygid-
ium, thus merging into the indefinite lateral border furrow. The
outline of the pygidium may have had a shallow median notch. Sur-
face of test smooth. Length of pygidium 1.7 mm., width 3.4 mm.

Occurrence.—Collection cs-23 (Centropleura bed), Judson Point.

Discussion.—This pygidium has many of the features of Hemi-
rhodon, differing mainly in the backward curve of the anterior border
furrow. If it does not belong to that genus it is likely to be at least
a close relative.

Disposition of material—Figured specimen: USNM 156675.

Corynexochacea, pygidium no. 3
Plate 14, figure 18

Available material—One incomplete example.

Description—Pygidium of low convexity, seemingly subquadrate
in shape. Axis fairly prominent, apparently consisting of 5 rings
plus a terminal section, extended into a short postaxial ridge that
probably reached the margin. There is a low node on each axial ring.
Outline of pleural lobe first directed straight outwardly from axial
furrow, sharply curving backward, and for some distance running
backward in straight line. The appearance of the broken test sug-
gests that there may have been a lateral spine, an extension of the
straight portion of the margin. The remainder of the pygidial mar-
gin is broken off, and it cannot be excluded that there may have been
more pairs of spines. Three pairs each of pleural and interpleural

go SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

furrows all about equally impressed, the anterior ones with a fairly
sharp backward bend, posteriorly becoming less curved and on the
average more backwardly directed. Surface of test smooth. Length
of pygidium approximately 2 mm., width 3.0 mm.

Occurrence.—Collection cs-23 (Centropleura bed), Judson Point.

Discussion.—This peculiar pygidium probably belongs to a doli-
chometopid trilobite, but cannot be more closely identified owing
to its imperfect preservation and lack of an associated cranidium.
The straight parallel sides are an unusual feature.

Disposition of material—Figured specimen: USNM 156676.

Corynexochacea, pygidium no. 4
Plate 7, figure 23

Available material—One well-preserved example.

Description.—Pygidium approximately twice wider than long, semi-
circular, with well-rounded anterior angles. Axis very prominent,
moderately tapered, rounded posteriorly, almost reaching posterior
margin. One axial ring well defined by a ring furrow; traces of a
second ring furrow indicated only at the sides. Pleural regions
with moderate relief, showing 3 pairs of broad, shallow pleural fur-
rows, and no trace of interpleural furrows. All the furrows die
out in the shallow, poorly defined border furrow. Border slightly
convex, also poorly defined. Anterior pygidial margin possessing a
sharp geniculation halfway between axial furrow and anterior angle.
Entire surface finely and densely granulate. Length of pygidium
3.4 mm., width 6.6 mm.

Occurrence.— Collection cs-3/L1 (Pagetides fauna), Griswold
farm.

Discussion—This pygidium resembles Corynexochus and Bon-
naspis, and may therefore represent a trilobite closely related to
these genera, which, however, occur in the late Middle Cambrian.
No definite statement about the affinities can be made in the absence
of an associated cranidium.

Disposition of material_—Figured specimen: USNM 156677.

Superfamily PARADOXIDACEA Hawle and Corda, 1847

Family CENTROPLEURIDAE Angelin, 1854
Genus CENTROPLEURA, Angelin, 1854

Type species: Centropleura loveni Angelin, 1854.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI g!I

CENTROPLEURA, species undetermined
Plate 11, figures 24-29

Available material—Fragments of two immature cranidia, genal
spines, a thoracic segment, and a pygidium.

Description—Larger cranidium preserving the anterior portion
of glabella and one palpebral lobe. All the observable features agree
with Centropleura, in particular the longitudinal course of the first
pair of glabellar furrows, which do not reach the second (trans-
glabellar) furrow.

The smaller (meraspid) cranidium preserves only the glabella
with occipital ring; seemingly it represents the youngest stage of
Centropleura so far illustrated. The glabella expands considerably
forward, and is characterized by a shallow longitudinal furrow
through the first three glabellar lobes. This furrow does not extend
onto the fourth glabellar lobe, which is shorter (sag.) than the first
three and defined by a deeper furrow anteriorly. The occipital
furrow is deep, and the occipital ring much narrower (tr.) than
the anterior part of the glabella. Fragments of genal spines show
the peculiar ornamentation illustrated by Opik (1961) in Centropleura
phoenix.

A thoracic segment, belonging to the anterior or middle portion
of the thorax, shows the characteristically short (tr.) pleurae, and
diagonal pleural furrow.

A small pygidium shows a short, sharply tapered axis including
two rings plus a terminal section. Pleural furrows curving back-
ward; pleural region with a low, transverse ridge behind the axis.
The marginal portion is not preserved enough to ascertain the pres-
ence of spines.

Occurrence.—Collection cs-23 (Centropleura faunule), Judson
Point.

Discussion—The fragmentary material presented herein, while
contributing nothing to the knowledge of the genus, is of consider-
able biostratigraphic significance, indicating the presence of late Mid-
dle Cambrian strata in the Taconic sequence, and relation of the fauna
to the Acado-Baltic province.

The reference to the genus is unquestionable, but it would be
meaningless to attempt specific identification. The fragments known
do not differ in any visible character from C. phoenix Opik from
Queensland, the best known of all species of Centropleura, but prob-
ably the same could be said for most of the described species. This
trilobite seems to have been common, since fragments of the genal

g2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

spines, recognizable by the characteristic ornamentation, frequently
occur on the bedding surfaces where fossil debris are concentrated.
Disposition of material—Figured specimens: USNM 156678.

Superfamily PTYCHOPARIACEA Matthew, 1887
Family CONOCORYPHIDAE Angelin, 1854

R. and E. Richter (1941, pp. 50-55) and Sdzuy (1961, pp. 658-660)
gave excellent discussions of the family Conocoryphidae, pointing out
that loss of the eyes in trilobites has little taxonomic significance.
As in modern organisms, it represents an adaptation to a mode of
life, which can occur in a number of unrelated groups. When the
blind Ptychopariacea become better known, each of their genera
must be referred to the family that includes closely related, oculate
forms.

Meneviella, and an unnamed form described herein, seem suffi-
ciently related to Conocoryphe to be referred to the family Conoco-
ryphidae in a restricted sense. However, as the above-cited authors
have pointed out, Atops has a different pattern of glabellar furrows
and should be excluded from the family. The writer fully agrees
with their suggestion that Atops is a very close relative of Rimouskia,
differing from the latter only in the loss of eyes and migration of
the facial suture toward the cephalic margin. Sdzuy (1961, p. 629)
suggests that Rimouskia should be excluded from the family Saoidae
(or subfamily Saoinae of the Solenopleuridae) where it was placed
by Hupé (1953) and the writer (1955). Therefore, Atops and
Rimouskia are referred herein to an undetermined family of the
Ptychopariacea.

Genus MENEVIELLA Stubblefield, 1951
Type species: Erinnys venulosa Salter, 1872
MENEVIELLA, species undetermined
Plate 14, figures 1-6

Available material—Small, mostly fragmentary cranidia, thoracic
segments, and a few pygidia.

Description.—The following description is based on cranidia 3-5
mm. in length; features of smaller, presumably meraspid cranidia
are mentioned later. Cranidium very regularly semicircular, exactly
twice wider than long, with straight posterior outline. Glabella mod-
erately tapered, occupying two-thirds of the cranidial length, narrow

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 93

in proportion to cranidium. Three pairs of lateral furrows short but
well impressed, of usual generalized ptychoparioid pattern. Occipital
furrow well impressed throughout ; occipital ring somewhat expanded
medially. Border furrow well impressed all around the cranidium.
Border convex, widest medially, but not narrowing much to the
genal angle, continued into the posterior border. The facial suture
must have been entirely marginal as it does not cut off any portion
of the border. A vague ocular ridge is directed outward and slightly
backward and disappears about the middle of the fixigenae. Surface
densely granulate, not showing the genal coeca even in cranidia 5 mm.
long.

Thoracic segments easily identifiable by the ornamentation. The
anterior ones with long, straight portion of pleurae and geniculation
very distally located. Posterior segments with geniculation situated
somewhat beyond halfway from axial furrow to pleural termination,
somewhat curving backward to a pointed end. All pleurae with broad,
deep furrow.

Pygidium more than twice wider than long, subelliptical. Axis
about two-thirds the pygidial length, not greatly elevated, posteriorly
almost merging with the pleural regions, showing 2 rigs plus a
terminal section. Pleural regions with 3 pairs of increasingly shallow
pleural furrows. Border furrow and border indistinct. Surface
densely granulate.

Cranidia about 1 mm. in length with glabella slightly expanded
rather than tapered in anterior portion, proportionately much longer
than in mature stages, reaching not far from border furrow. Glabellar
furrows indistinct; occipital furrow well impressed; occipital ring
bearing a node. Fixigenae with strong convexity, showing faint
ocular ridges. Border well defined; border furrow almost merging
with the axial furrow medially through a preglabellar depression.
The facial suture seems to have been entirely marginal. Surface
granulate.

Occurrence——Most of the illustrated specimens are from loose
blocks on the Griswold farm (coll. cs-7/M1 and cs-8/M1). Also
present in collection cs-9d* at the Malden Bridge road cut. In all
cases in association with Ptychagnostus gibbus and other trilobites
of the Bathyuriscus-Elrathina zone.

Discussion.—The reference to the genus seems unquestionable,
as only minor differences separate the species from Meneviella venu-
losa, chiefly the convex rather than flat cephalic border and the
lack of distinct genal coeca. The immature cranidia are extremely
similar to specimens of the same size figured by Hutchinson (1962).

94 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

The occurrence of Meneviella is particularly interesting in view of
the association of this typically Acado-Baltic trilobite with genera
representative of the Cordilleran province such as Bathyuriscus
and Kootenia. In Newfoundland Hutchinson (1962) found Mene-
viella venulosa in the upper part of the Paradoxides hicksi and
throughout the Paradoxides davidis zones, indicating approximately
the same age as for the present species.

Disposition of material—Figured specimens: USNM 156679-80.

Genus undetermined
Conocoryphidae, cranidium no. 1

Plate 8, figure 22

Known from one immature example. Glabella parallel-sided, well
rounded in front, with but traces of lateral furrows. Occipital fur-
row well impressed, occipital ring apparently simple. Genae with
considerable convexity; preglabellar field longer (sag.) than border
width. Border furrow deep, anterior border convex, apparently
reduced in width at the sides and possibly totally cut off by the
facial suture in posterolateral part of genae. Posterior border furrow
deep, straight. Ocular ridges lacking. Surface granulate. Length
of cranidium 1.8 mm., maximum width 2.8 mm.

The cranidium is typical of the Conocoryphidae but too immature
for generic identification. The specimen is illustrated because tri-
lobites of this type do not seem to have been reported from Lower
Cambrian strata.

Occurrence.—Loose block cs-15/L1, in association with a Lower
Cambrian Pagetides faunule.

Disposition of material—Figured specimen: USNM 156681.

Family MENOMONIIDAE Walcott, 1916
Genus BOLASPIDELLA Resser, 1937
Type species: Ptychoparia housensis Walcott, 1886.
BOLASPIDELLA FISHERI, new species
Plate 13, figures 17-30

Available material—A few holaspid cranidia and free cheeks,
and numerous meraspid cranidia. The material is well preserved
in limestone.

Description—The following description applies to the larger crani-

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 95

dia and free cheeks, believed to represent holaspid stages. Glabella
defined by deep axial furrow, slightly tapered, truncate in front.
Two pairs of short furrows impressed laterally; occipital furrow
deep and straight; occipital ring considerably expanded backward
medially, rounded, bearing a small node. Preglabellar field short
(sag.) ; border elevated, convex, tapering in width laterally. Palpe-
bral area upsloping, somewhat more than half the glabellar width.
Palpebral lobe large, almost half the glabellar length, bean-shaped,
considerably elevated above the palpebral area, connected to glabella
by a low ocular ridge. Distance from posterior end of palpebral lobe
to posterior cranidial margin somewhat less than length of palpebral
lobe. Anterior facial sutures not divergent, curving inward and
rounding off the anterior angles of the cranidium. Posterior branch
directed outward, defining a parallel-sided posterior area, downsloping
in distal portion and deeply furrowed.

Free cheek with steeply downsloping ocular platform. Border rela-
tively wide, sharply raised above the border furrow, somewhat in-
creasing in width posteriorly, extended into short, rapidly tapered
genal spine. Border extending inward, hence forming portion of
posterior border of cephalon, the facial suture showing a sharp
angle corresponding to the termination of the posterior area of the
cranidium.

Surface covered with rather small granules of different sizes. On
the border of cranidium and free cheeks the distinction between
large and small granules is sharper. Length of holotype cranidium
2.2 mm.

Ontogeny.—Immature cranidia, mostly belonging to meraspid
stages, are much more common than larger examples. Protaspides
may be present in the collection, but are difficult to identify among
the numerous ptychoparioid species. The smallest cranidia definitely
referable to the species have a length of 0.5 mm. The glabella is
narrow, well defined by axial furrows posteriorly, but fading out
into the frontal area. Occipital furrow and ring are well developed.
The entire area of the genae is convex, lacking a differentiated border.
Cranidia 0.67 mm. long already show the entire outline of the glabella,
defined by deep axial furrows and slightly tapered in posterior portion,
the remainder defined by excessively shallow axial furrows, slightly
expanding forward, sharply truncate in front, almost reaching frontal
margin of cranidium. Faint glabellar furrows are visible at this
stage; the occipital furrow is deep. The short (sag.) frontal area
is still undifferentiated by a border furrow. The palpebral lobes
are indistinct. The posterior border on the fixigenae widens distally,

96 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

and is well defined by a deep border furrow. In cranidia 0.85 mm.
long four pairs of shallow glabellar furrows are visible on coated
specimens. The glabella still slightly expands in anteriormost portion.
Faint ocular ridges and very small, inconspicuous palpebral lobes
appear. The lateral cranidial outline becomes straight rather than
rounded, especially in the portion that includes the palpebral lobe;
the latter is located in a much more anterior position than in later
stages. The frontal border becomes differentiated, but still there
is no preglabellar field. Cranidia 1.1 mm. long are intermediate
between the last described stage and the holaspid. The glabella no
longer expands forward and there is a trace of preglabellar field.
Ocular ridges and palpebral lobes become more conspicuous, the
latter being longer and slightly elevated above a shallow palpebral
furrow, but the great elevation of the palpebral area and lobe as
observed in the holaspid does not yet occur. The general side out-
line of the cranidium becomes concave outward, the facial suture
being directed definitely outward behind the palpebral lobe.

These features of the ontogeny closely parallel those observed by
Robison (1964a) in Bolaspidella housensis, in particular the late de-
velopment of large and elevated palpebral lobes that are charac-
teristic of the holaspids of the genus.

The species is named for Dr. Donald W. Fisher.

Occurrence.—Collection cs-21, Stockport Station.

Discussion.—The species differs from both B. housensis and B.
drumensis, well illustrated by Robison (1964a), in the lack of an
occipital spine. B. contracta Robison shares with the present species
the lack of an occipital spine, but has a proportionately narrow
glabella, especially in its posterior part, and smaller, more anteriorly
located palpebral lobes. The species from Utah have much longer
genal spines.

Types——Holotype: USNM 156682. Paratypes: USNM 156683.

Family undetermined
Genus RIMOUSKIA Resser, 1938
Type species: Rimouskia typica Resser, 1938.
RIMOUSKIA TYPICA Resser
Plate 9, figures 1-3

Rimouskia typica REsssEr, 1938, p. 98, pl. 3, figs. 20-22.
Rimouskia spinosa REssEr, 1938, p. 98, pl. 3, fig. 19.
Rimouskia typica Resser, RAsEtTI, 1955, p. 31, pl. 1, fig. 10; pl. 6, figs. 1-6.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 97

Two good cranidia and a librigena were recovered. Librigena
very narrow, with a slightly raised border. Anterior and posterior
branches of the facial suture almost in a straight line. The inner
margin shows a narrow, short extension corresponding to the rounded
distal portion of the posterior area of the cranidium. The librigena
extends into a short, rapidly tapered genal spine. The ornamentation
consists of granules of different sizes as that of the cranidium.

Occurrence.—The species had so far been found only in conglom-
erate boulders at Bic, Quebec, and its only known associations were
olenellid fragments. In the Taconic sequence it was collected from
boulders in the Ashley Hill Conglomerate at Ashley Hill (coll. cs-19),
in association with Elliptocephala asaphoides, Calodiscus lobatus,
Hyolithellus micans, and Helcionella subrugosa, and from shale at
Judson Point (coll. cs-24b), associated with Atops trilineatus, Ellip-
tocephala asaphoides, and Serrodiscus speciosus.

Types.—Plesiotypes figured herein: USNM 156684.

Genus ATOPS Emmons, 1844
Type species: Atops trilineatus Emmons, 1844
ATOPS TRILINEATUS Emmons
Plate 8, figure 23

Atops trilineatus Emmons, 1844, p. 20, pl. 2, fig. 3.
Atops trilineatus Emmons, LocuHMan, 1956, p. 1383, pl. 6, fig. 1. Complete
synonymy to date.

In the area investigated, Atops trilineatus was collected only from
shale at Judson Point. The species has been found at several locali-
ties in the Taconic sequence, almost invariably in shale, even though
other members of the Elliptocephala asaphoides assemblage are much
more common in limestone.

The cranidium of Rimouskia typica is virtually identical with
that of Atops trilineatus, except in the course of the facial suture and
presence of palpebral lobes. Unfortunately the other parts of the
exoskeleton of Rimouskia are unknown. The two species were col-
lected from the same shale bed at Judson Point.

Occurrence.—Same beds as author’s collection 24b, Judson Point
(collected by H. B. Whittington).

Types.—Plesiotype: MCZ 8536.

Genus ELRATHIA Walcott, 1924
Type species: Conocoryphe (Conocephalites) kingti Meek, 1870

98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

ELRATHIA?, species undetermined
Plate 14, figures 7, 8

Available material—Two cranidia, presumably immature.

Description—Glabella almost parallel-sided, moderately truncate in
front, unfurrowed. Occipital furrow well impressed, occipital ring
short (sag.), bearing a small node. Frontal area about half as long
(sag.) as glabella. Preglabellar field more than twice as wide (sag.)
as border; the latter convex, moderately elevated. Palpebral area
slightly convex, on the average horizontal, somewhat less than the
glabellar width. Palpebral lobes about a third the glabellar length,
moderately elevated, at level of glabellar midpoint; ocular ridges
transverse, not greatly elevated. Posterior area of fixigenae some-
what tapered distally, well furrowed, wider (tr.) than occipital ring
or glabella. Surface of test indistinctly granulate. Length of larger
cranidium 2.0 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion.—This cranidium resembles Elrathia in the general
proportions, but differs from described species in the narrow and
more parallel-sided glabella. This may be a feature due to the imma-
ture condition of the specimens.

Disposition of material_—Figured specimens: USNM 156685.

Genus ELRATHINA Resser, 1937
Type species: Conocephalites cordillerae Rominger, 1887.
ELRATHINA?, species undetermined
Plate 14, figure 20

Available material—A few imperfect cranidia.

Description.—Glabella slightly tapered in posterior part, becom-
ing parallel-sided, rounded in front, rising above the genae. Traces
of two pairs of glabellar furrows visible at the sides. Occipital furrow
moderately deep; occipital ring extended into a small spine. Frontal
area moderately arched transversely; preglabellar field short (sag.),
about equaling the width of the border medially. Border tapering in
width at the sides, well defined by border furrow which is deeper
laterally, very shallow medially. Palpebral area convex transversely,
almost as wide as glabella; ocular ridges slightly arched, on the
average transverse in direction; palpebral lobes incompletely pre-
served, at level of anterior third of glabella. Anterior facial sutures
definitely convergent in dorsal view. Posterior branch almost straight,

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 99

with little change of direction from anterior branch, forming large,
widely furrowed posterior area. Surface of test smooth. Length of
best-preserved cranidium 5.6 mm.

Occurrence.—Collection cs-6 (Bathyuriscus-Elrathina zone), Gris-
wold Farm.

Discussion—This form is too incompletely known for a reliable
generic identification; however, it appears to fit better in Elrathina
than in any other described genus. The anterior position of the
palpebral lobe is the only characteristic which disagrees with the
typical forms of the genus.

Disposition of material—Figured specimen: USNM 156686.

Genus MODOCIA Walcott, 1924

Type species: Arionellus (Crepicephalus) oweni Meek and Hay-
den, 1861,

MODOCIA PUNCTATA, new species
Plate 12, figures 24-28

Available material—Several cranidia, very small and presumably
immature.

Description.—Glabella strongly convex in both directions, unfur-
rowed, well rounded in front. Occipital furrow deep; occipital ring
expanded medially, lacking node or spine. Fixigenae convex and
downsloping ; preglabellar field somewhat longer(sag.) than border,
at least in the larger cranidia. Border elevated, convex, tapering
in width at the sides. Palpebral area convex transversely, mostly
downsloping, less than half the glabellar width in the larger cranidia.
Ocular ridges indistinct; palpebral lobe increasing in relative size
in the larger examples, attaining somewhat more than a fourth the
glabellar length, defined by palpebral furrow deeper in posterior
part. Anterior facial sutures not appearing divergent in dorsal view ;
posterior branch directed progressively more outward in larger
cranidia, producing blunt, deeply furrowed posterior area, which is
somewhat narrower (tr.) than occipital ring. Distance from pos-
terior end of palpebral lobe to posterior cranidial margin somewhat
greater than length of palpebral lobe. Surface of test markedly
punctate, especially in the larger cranidia. The available cranidia
vary in length from 1.0 to 2.7 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion —This form resembles Modocia metisensis (Walcott)

100 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

in the plump appearance of the glabella, differing from that species
in the longer preglabellar field, somewhat different form of the palpe-
bral lobe, and especially the pitted rather than granulate surface.
Were it not for the last feature, so far unique in the genus, one
might suspect that the differences from M. metisensis or possibly other
described species are due to the immature condition of the specimens.

Types.—Holotype: USNM 156687. Paratypes: USNM 156688.

MODOCIA, species undetermined
Plate 14, figure 26

Two cranidia associated with Modocia punctata differ from that
species in the less plump, more nearly straight-sided glabella, longer
(sag.) frontal area, wider and less convex border equaling in width
(sag.) the preglabellar field, and somewhat divergent anterior facial
sutures. This form resembles M. brevispina Robison (1964a). The
occipital ring is broken off, hence it cannot be ascertained whether
an occipital spine was present. The surface is smooth.

Occurrence.—Collection cs-21.

Disposition of material—Figured specimen: USNM 156689.

Genus undetermined
Ptychopariacea, cranidium no. 1
Plate 7, figures 24-26

Available material—A few examples, probably immature.

Description.—Glabella parallel-sided, rounded in front. Two or
3 pairs of shallow to moderately deep lateral furrows visible, of
generalized ptychoparioid pattern. Occipital furrow deeper laterally,
occipital ring rounded, bearing a node. Preglabellar field at least
in smaller specimens shorter (sag.) than border medially, in larger
specimen about equaling border. Border convex, tapered in width
laterally. Palpebral area approximately horizontal, with little con-
vexity; ocular ridges broad and low, first directed outward, curving
backward. Palpebral lobe about one fourth the glabellar length, nar-
row, obliquely directed, slightly elevated, situated in advance of
glabellar midpoint. Anterior facial sutures definitely convergent in
front of the eyes, probably marginal for a short median portion;
posterior branch extending without much change of direction to
posterior margin. Posterior area with well impressed, straight fur-
row, considerably wider (tr.) than occipital ring. Surface finely

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI IoI

granulate. Length of smaller, better preserved cranidia 2.0 mm, of
larger example 2.8 mm.

Occurrence.—Collections cs-9, Malden Bridge, cs-4a, Griswold
farm, and loose block cs-15/L1. Examples from the last collection
are poorly preserved and reference to the same species is somewhat
doubtful. In the first two collections associated with Neopagetina
and Pagetides.

Discussion—This generalized ptychoparioid resembles several
genera known from the Lower Cambrian of North America but the
parallel-sided glabella, anterior position of eyes, and narrowness of
the frontal part of the cranidium are somewhat unusual. It is pos-
sible that these features are emphasized by the immaturity of the
specimens. Eoptychoparia is probably the nearest described genus.

Disposition of material_—Figured specimens: USNM 156690-2.

Ptychopariacea, cranidium no. 2
Plate 14, figures 11-13

Available material—Several, well preserved examples, all very
small and presumably immature.

Description ——Glabella approximately parallel-sided, reaching an-
terior border, in the smaller specimens slightly hourglass-shaped, in
larger ones becoming straight-sided and very slightly tapered. All
specimens show a very shallow median notch in the truncate anterior
outline. Two pairs of very shallow glabellar furrows visible at the
sides. Occipital furrow well impressed; occipital ring extended into
a rapidly tapered spine. Anterior border narrow, convex, wirelike,
strongly arched in dorsal view. Fixigenae convex and downsloping,
broadening posteriorly, the facial sutures continuing the outline of
the anterior border without much change in direction. Palpebral
area about two-thirds the width of glabella; palpebral lobes very
narrow, inconspicuous, located in advance of glabellar midpoint.
Ocular ridges very faint, parallel and close to anterior border. Trans-
verse width of posterior area slightly exceeding width of occipital
ring. Furrow on posterior area deep, diverging outward from poster-
ior cranidial margin; posterolateral angles of cranidium narrowly
rounded. Surface of test smooth. Length of largest cranidium
1.2 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion —This cranidium does not seem referable to any de-
scribed genus. However, in view of the almost certainly immature

I02 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

features of the available specimens, it would be improper to use the
material for proposing new taxa.
Disposition of material—Figured specimens: USNM 156693.

Ptychopariacea, cranidium no. 3
Plate 14, figures 9, 10

Available material—A few, fairly well preserved, presumably
immature examples.

Description—Cranidium subtrapezoidal, fairly convex. Glabella
almost parallel-sided, slightly constricted medially in smaller indi-
viduals, becoming slightly tapered in the larger ones, bearing but
traces of lateral furrows, truncate or even slightly indented in front,
reaching border furrow. Occipital furrow deep; occipital ring ex-
tended into spine. Anterior border convex, wide (sag.) medially,
rapidly tapered laterally, with curved anterior outline but posteriorly
bounded by almost straight border furrow. Palpebral area somewhat
narrower than glabella; ocular ridges parallel and close to anterior
border furrow, very faint; palpebral lobes very narrow and but
slightly elevated, somewhat anterior to level of glabellar midpoint.
Anterior facial sutures strongly convergent ; posterior branch show-
ing little change of direction from anterior branch, only curving
inward sharply in crossing the posterior border furrow, producing
fairly sharp posterolateral angle of cranidium. Posterior border
furrow well impressed, broadening and becoming shallower outward.
Surface of test with coarse, very shallow puncta. Length of largest
cranidium 1.4 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion.—This form, as far as can be evaluated from imma-
ture material, closely resembles the preceding and should presumably
be considered congeneric. It differs from cranidium no. 2 in the
straighter, wider and laterally tapered anterior border, less com-
plete merging of border and axial furrows, and punctate surface.

Disposition of material—Figured specimens: USNM 156694.

Ptychopariacea, cranidium no. 4

Plate 14, figure 17

Available material—A single, small and presumably immature
example.
Description.—Glabella straight-sided, very slightly tapered, well

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 103

rounded in front, unfurrowed. Occipital furrow straight, well im-
pressed ; occipital ring broadened medially, rounded, lacking spine or
node. Preglabellar field short (sag.) ; border furrow well impressed ;
border convex, moderately wide, uniformly curved in anterior out-
line, not much tapered in width at the sides. Palpebral area some-
what less than half the glabellar width; ocular ridges indistinct;
palpebral lobes almost half the length of glabella, defined by very
shallow palpebral furrow, curved, not greatly elevated. Distance of
posterior end of palpebral lobe to cranidial margin less than length
of palpebral lobe. Posterior area not preserved, seemingly slender.
Surface of test smooth. Length of cranidium 1.7 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion.—This cranidium is of a fairly generalized ptychopari-
oid type. It would be futile to attempt generic identification on an
immature individual.

Disposition of material—Figured specimen: USNM 156695.

Ptychopariacea, cranidium no. 5
Plate 14, figure 24

Available material—A few, imperfect, presumably immature ex-
amples.

Description—Glabella parallel-sided, truncate in front, reaching
anterior border furrow. Two pairs of glabellar furrows impressed
at the sides ; anterior pair shallower, transverse ; posterior pair deeper,
directed slightly inward and backward, at inner end extended into a
very shallow portion curving backward. Occipital furrow deep; oc-
cipital ring subtriangular, forming a short, obtuse spine. Anterior
border convex, well defined by border furrow, not greatly curved,
tapered in width laterally. Other portions of cranidium not pre-
served. Surface granulate. Length of best-preserved cranidium
1.1 mm.

Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook.

Discussion.—As far as one can evaluate the poorly preserved,
immature material, this cranidium seems closely related to Weller-
aspis, a genus so far known from Dresbachian strata. In the discus-
sion of the faunas it was shown that associated fossils give strong
indication for a late Middle Cambrian age.

Disposition of material—Figured specimen: USNM 156696

104 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Ptychopariacea, cranidium no. 6
Plate 14, figure 15

Available material—aAn exceedingly small, immature example.

Description—Cranidium short and wide, with little convexity.
Glabella very long and narrow, parallel-sided, reaching anterior
border furrow, unfurrowed. Occipital furrow straight and deep;
occipital ring short (sag.), rounded. Fixigenae very wide, posteriorly
about 24 times as wide as glabella. Anterior border flat, fairly well
defined, very short (tr.) in proportion to posterior part of cranidium.
Palpebral lobes about as distant from glabella as glabellar width,
very anteriorly situated, at about one fifth the distance from anterior
to posterior cranidial margin. Fixigenae greatly expanded behind
palpebral lobes. Posterior angles of cranidium very sharp, possibly
indicating proparian suture. Furrow on posterior area narrow and
very close to margin. Surface of test with a few, widely spaced
granules. Length of cranidium 0.55 mm.

Occurrence.—Collections cs-22 (Bolaspidella zone), Nutten Hook.

Discussion—Even though it is difficult to estimate the features
of the adult from such an immature, presumably meraspid cranidium,
the characters of the specimen are so unusual that it is likely to
belong in an undescribed genus of uncertain affinities.

Disposition of material—Figured specimen: USNM 156697.

Ptychopariacea, cranidium no. 7
Plate 14, figures 21, 22

Available material—Two imperfect, very small examples.

Description—Glabella large, with slightly concave sides, some-
what expanded forward, rising high above the fixigenae, reaching
anterior cranidial margin. Posteriormost pair of glabellar furrows
impressed in form of short, oblique furrows at the sides; another
pair of furrows similar but very shallow. Occipital furrow deep,
strongly concave forward; occipital ring not well preserved, seem-
ingly extended into spine. Anterior cephalic border very narrow
or entirely missing. Ocular ridge very close and parallel to cranidial
margin, extending into very narrow, oblique palpebral lobe, the poor
preservation not allowing to determine the precise boundary between
the two. Surface of test finely granulate. Length of cranidium
0.7 mm.

Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook,

Discussion.—This cranidium, as far as its features can be ascer-

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 105

tained, is most suggestive of the Trempealeauian genus Theodenisia
or the Dresbachian Pemphigaspis. However, the resemblance may
be due to the juvenile features of the present material, as the writer
(Rasetti, 1954) has shown that meraspid forms of lonchocephalid
trilobites may assume a similar aspect. Relatives of the above-men-
tioned genera are known from late Middle Cambrian strata, such
as Catillicephala in the St. Albans Shale (Shaw, 1966).
Disposition of material—Figured specimens: USNM 156698.

Ptychopariacea, cranidium no. 8
Plate 14, figure 25

Available material—A very small, probably immature example.

Description.—Glabella narrow and long, parallel-sided, subtruncate
in front, lacking distinct furrows. Occipital furrow deep, occipital
ring extended into a strong, subhorizontal spine. Frontal area con-
sisting of short (sag.) preglabellar field and elevated, laterally
tapered, rather straight border. Palpebral area flat, wider than gla-
bella; ocular ridges indistinct; palpebral lobe small, not considerably
elevated, anterior to glabellar midpoint. Facial sutures slightly con-
vergent in front of eyes; posterior branch directed outward and
backward, producing large, distally rounded posterior area. Furrow
on posterior area deep and wide. Surface apparently smooth. Length
of cranidium, exclusive of occipital spine, 0.9 mm.

Occurrence.—Collection cs-23, Judson Point.

Discussion.—It is difficult to assess the affinities of this form on
account of the immature stage of the only specimen available. It
may represent a relative of Bolaspidella, even though the species of
that genus, as for example B. fisheri described herein, show very
different features in examples of the same size.

Disposition of material_—Figured specimen: USNM 156638.

Ptychopariacea, pygidium no. 1
Plate 14, figure 16

Available material_—One example.

Description —Pygidium subelliptical, with considerable relief. Axis
rapidly tapered, prominent, rounded posteriorly, reaching the border
furrow, composed of 3 definite rings plus a terminal section. Pleural
regions downsloping; 3 pairs of pleural furrows well impressed,
with even curvature, ending in poorly defined border furrow. Inter-
pleural furrows shallower, impressed only distally. Border poorly

106 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

defined, flat, narrower medially. Surface of test apparently smooth.
Length of pygidium 0.9 mm, width 1.6 mm.

Occurrence.—Collection cs-21 (Bolaspidella zone), Stockport Sta-
tion.

Discussion—This generalized ptychoparioid pygidium resembles
Modocia and a number of other genera.

Disposition of material—Figured specimen: USNM 156699.

Ptychopariacea, pygidium no. 2
Plate 14, figure 19

Available material—One example.

Description—Pygidium approximately semicircular. Axis tapered,
reaching about three fourths the length of pygidium, composed of
3 rings plus a terminal section, narrowly rounded posteriorly. Pleural
regions moderately convex; anterior outline straight, transverse for
over half the distance from axial furrow to anterior angle, rather
sharply curving backward in distal portion; remainder of pygidial
outline of almost even curvature. Anterior border furrow deep and
broad ; two other pairs of pleural furrows vaguely impressed proxim-
ally, fading out distally; one pair of interpleural furrows faintly de-
fined in proximal portion. Border furrow and border undifferentiated.
Surface of test with fine granulation, plus a few pairs of larger,
scattered granules. Length of pygidium 1.0 mm., width 2.0 mm.

Occurrence.—Collection cs-23 (Centropleura bed), Judson Point.

Discussion.—The pattern of pleural furrows and the lack of border
furrow and border give this pygidium a somewhat unusual aspect.
Lack of an associated cranidium prevents any attempt at classification.

Disposition of material—Figured specimen: USNM 156700.

Ptychopariacea, pygidium no. 3
Plate 14, figure 29

Available material_—One example.

Description.—Pygidium broadly subtriangular, with moderate over-
all relief. Axis proportionately broad and short, elevated, composed
of 2 rings plus a terminal section, well rounded posteriorly, occupy-
ing two thirds of the pygidial length. Pleural regions almost flat
and horizontal; anterior border furrow and one pair of narrow
pleural furrows impressed only proximally ; no interpleural furrows.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI 107

Posterior margin of pygidium downrolled, lacking definite border
furrow or border. Surface densely covered with small, elevated gran-
ules. Length of pygidium 1.1 mm., width 2.2 mm.

Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook.

Discussion.—This pygidium, even though the proportions are the
same as in most ptychoparioid genera, has characteristic features in
the small number of axial segments, flatness of the pleural regions,
and lack of differentiated border furrow and border. In the absence
of an associated cranidium, even generic identification cannot be
attempted.

Disposition of material—Figured specimen: USNM 156701.

Ptychopariacea, pygidium no. 4
Plate 14, figures 27, 28

Available material—A few fragmentary examples, of which two are
relatively complete.

Description—Pygidium subtriangular, with considerable relief.
Axis very prominent, slightly tapered, occupying the entire pygidial
length, composed of 4 well-defined rings plus a terminal section; in
the latter further traces of segmentation may be visible. Anterior
margin of pleural region with geniculation situated very close to axial
furrow; portion of outline distal to geniculation directed obliquely
outward and backward. Remainder of outline posterior to anterior
angles fairly straight on each side, rather sharply rounded behind
axis. Pleural regions convex and downsloping, showing 4 rather
deep pairs of pleural furrows, and in the smaller of the figured speci-
mens also distally impressed interpleural furrows. All furrows
terminate in shallow border furrow, which sets off a narrow, flat
border. Ornamentation indistinct. Length of largest pygidium 1.2
mm., width 2.2 mm.

Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook.

Discussion.—This pygidium somewhat resembles Welleraspis, but
its generalized ptychoparioid features make a definite identification
inadvisable. The pygidium might conceivably belong with the ptycho-
parioid cranidium no. 5. Even though the two illustrated specimens
show difference in the depth of the furrows, they are probably to
be considered conspecific.

Disposition of material—Figured specimens: USNM 156702.

108 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152

Ptychopariacea, pygidium no. 5
Plate 14, figure 23

Available materiak—One example.

Description —Entire pygidium short and wide, of moderate relief,
with almost straight anterior and uniformly curved posterior outline.
Axis elevated above the pleural regions, slightly tapered, showing 5
rings plus a short terminal section separated by shallow furrows,
almost reaching the posterior border. Pleural regions downsloping
only in outer portion, showing 4 pairs of pleural furrows (including
the anterior border furrow) and as many pairs of interpleural furrows,
all equally impressed, directed outward in proximal portion, curving
backward only distally, all ending in narrow, shallow border furrow.
Border narrow, wirelike, defined rather by its elevation than by a
border furrow. Surface of test smooth. Length of pygidium 0.75
mm., width 1.75 mm.

_ Occurrence.—Collection cs-22 (Bolaspidella zone), Nutten Hook.

Discussion—The depth of both pleural and interpleural furrows,
combined with the narrow, elevated border represent unusual features
among late Middle Cambrian ptychoparioid trilobites.

Disposition of material—Figured specimen: USNM 156703.

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1961. The geology and palaeontology of the headwaters of the Burke River,
Queensland. Commonwealth of Australia, Bureau Min. Res. Geol.
Geophys. Bull. 53, 249 pp., 24 pls.
RASETTI, FRANCO
1945. Fossiliferous horizons in the “Sillery formation” near Levis, Quebec.
Amer. Journ. Sci., vol. 243, pp. 305-319, pls. 1, 2.
1948a. Lower Cambrian trilobites from the conglomerates of Quebec (exclu-
sive of the Ptychopariidea). Journ. Paleontol., vol. 22, pp. 1-24,
pls. 1-6.
1948b. Middle Cambrian trilobites from the conglomerates of Quebec (exclu-
sive of the Ptychopariidea). Journ, Paleontol., vol. 22, pp. 315-339,
pls. 45-52.
1951. Middle Cambrian stratigraphy and faunas of the Canadian Rocky
Mountains. Smithsonian Misc. Coll., vol. 116, no. 5, 277 pp., 34 pls.
1952. Revision of the North American trilobites of the family Eodiscidae.
Journ. Paleontol., vol. 26, pp. 434-451, pls. 51-54.
1954. Phylogeny of the Cambrian trilobite family Catillicephalidae and the
ontogeny of Welleraspis. Journ. Paleontol., vol. 28, pp. 599-612,
pl. 62.
1955. Lower Cambrian ptychopariid trilobites from the conglomerates of
Quebec. Smithsonian Misc. Coll., vol. 128, no. 7, 35 pp., 6 pls.
1966a. New Lower Cambrian trilobite faunule from the Taconic sequence of
New York. Smithsonian Misc. Coll., vol. 148, no. 9, 52 pp., 12 pls.
1966b. Revision of the North American species of the Cambrian trilobite
genus Pagetia. Journ. Paleontol., vol. 39, pp. 502-511, pls. 59, 60.
RASETTI, FRANCO, and THEOKRITOFF, GEORGE
1967. Lower Cambrian agnostid trilobites of North America. Journ. Paleon-
tol., vol. 41, pp. 189-196, pl. 20.
REssER, C. E.
1938. Cambrian system (restricted) of the southern Appalachians. Geol.
Soc. America Special Paper 15, 140 pp., 16 pls.
Resser, C. E., and Howe tt, B. F.
1938. Lower Cambrian Olenellus zone of the Appalachians. Geol. Soc.
America Bull., vol. 49, pp. 195-248, pls. 1-13.
RICHTER, Rupotr, and RIcHTER, EMMA
1941. Die Fauna des Unter-Kambriums von Cala in Andalusien. Abh.
Senckenbergischen Naturf. Ges. (Frankfurt), Abh. 455, 90 pp.,
4 pls.
Rostson, R. A.
1964a. Late Middle Cambrian faunas from western Utah. Journ. Paleontol.,
vol. 38, pp. 510-566, pls. 79-92.
1964b. Middle-Upper Cambrian boundary in North America. Geol. Soc.
America Bull., vol. 75, pp. 987-994.

NO. 4 TRILOBITES, TACONIC SEQUENCE—RASETTI ie i

RUEDEMANN, RUDOLF
1942. Geology of the Catskill and Katerskill quadrangles. Pt. 1, Cambrian
and Ordovician geology of the Catskill quadrangle. New York
State Mus. Bull. 331, pp. 1-188.
RusHtTon, A. W. A.
1966. The Cambrian trilobites from the Purley Shales of Warwickshire.
Palaeontogr. Soc. Mon., vol. 120, publ. 511, pp. 1-55, pls. 1-6.
Spzuy, Kraus
1960. Das Kambrium von Deutschland. Rept. Intern. Geol. Congress, XXI
Session (Copenhagen), pt. 8, pp. 102-112.
1961. Das Kambrium Spaniens. Teil II: Trilobiten. Akad. Wissensch.
Liter. (Mainz), Abh. Math. Naturw. Klasse, nos. 6, 7, pp. 501-693,
pls. 1-34.
SHaw, ALAN B.
1966. Paleontology of northwestern Vermont. XI: Fossils from the Middle
Cambrian St. Albans Shale. Journ. Paleontol., vol. 40, pp. 843-858,
pls. 97-99.
Snaypr, MILAN
1958. Trilobiti Geského stfedniho kambria. Rozpravy Ustfedniho ustavu
geologického (Prague), Svazek 24, 280 pp., 46 pls. [with English
summary ].
TCHERNYSHEVA, N. E.
1960. Fundamentals of Paleontology: References to the Paleontology and
Geology of the U. S. S. R. [in Russian]. Trilobitomorpha and
Crustacea. Acad. Sci. U. S. S. R. (Moskow), 515 pp., 18 pls.
T HEOKRITOFF, GEORGE
1964. Taconic stratigraphy in northern Washington County, New York.
Geol. Soc. America Bull., vol. 75, pp. 171-190, pls. 1-3.
Watcorrt, C. D.
1891. The fauna of the Lower Cambrian or Olenellus zone. U. S. Geol.
Survey Tenth Ann. Rept., pp. 515-629, pls. 49-98.
WeEsTERGArRD, A. H.
1946. Agnostidea of the Middle Cambrian of Sweden. Sveriges Geol.
Unders., Arsbok 40, no. 1, ser. C, no. 477, 140 pp., 16 pls.
1953. Non-agnostidean trilobites of the Middle Cambrian of Sweden.
Sveriges Geol. Unders., Arsbok 46, no. 2, ser. C, no, 526, 58 pp.,
8 pls.
Wuittarp, W. F.
1952. A geology of South Shropshire. Proc. Geol. Assoc., vol. 63, pt. 2,
pp. 143-197.

PLATE 1

Page

Kiss 1. Leptochilodiscus pinctulatus Rasettt. = =. 4%.) 2) 0s) eee 48

Lateral and dorsal views of cephalon; dorsal and posterior views of
pygidium, 5.

Big-e2, Stigmadiscus stcnometopus: Rasetti . 9. =. >» 2. |. 9s) eo
Pygidium tentatively referred to the species, «4.

Fig: 3: serrodiscus spuiilosus: Rasefty i <p 00 \ ue 2 oe ie
Cephalon ; dorsal and lateral views of pygidium, 5.

Bigw 4s .Colodsscus, walcoti. Rasettt ) 2 tee ee 45

Cephalon, pygidium, 10.

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 1

LOWER CAMBRIAN EODISCIDAE

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 2

LOWER CAMBRIAN TRILOBITES

PLATE 2

Figs. 1-3. Acidiscus hexacanthus Rasetti oN ee
1, Portion of pygidium showing ornamentation, x75. 2, 3, Dorsal
and lateral views of same pygidium, 3 (coll. cs-4). USNM 156574,
plesiotype.
Fig. 4. Acidiscus birdi Rasetti .
Posterolateral portion of cephalon ecoaing pe es fide, x4 (coll.
cs-4), USNM 156573, plesiotype.
Figs. 5-7. Analox obtusa, new species ee or, AC oe
5, Cephalon, 7.5 (coll. cs-3/L2), USNM 156575, holotype. 6,
Cephalon, X10. 7, Pygidium, 10 (coll. es-3/L2). USNM 156576,
paratypes.
Figs. 8-12. Bolboparia, species no. 1 . LP a
8-10, Posterior, lateral, and dorsal views At pyg metitacn: X75. lake
Fragment of silicified pygidium showing spines and portion of border,
15. 12, Cephalon, <7.5 (coll. cs-9a). USNM 156577.
Figs. 13, 14. Bolboparia canadensis Rasetti .
Lateral and dorsal views of pygidium, 6 (coll. Sibert 63- F24, near
Elgin Station, Quebec), GSC 10563.
Fig. 15. Bolboparia, species no. 2 .
Pygidium, 7.5 (coll. cs-15/L4), USNM 156578.
Figs. 16-19. Calodiscus theokritoffi, new species. le ee
16, 17, Dorsal views of cephalon and cast of SoRieace. paar bE
Lateral view of same specimen (coll. Hubert 63-F24, near Elgin
Station, Quebec). GSC 10564, holotype. 19, Silicified cephalon,
7.5 (coll. cs-9a). USNM 156581, paratype.

Page
4]

40

41

43

44

PLATE 3

Fig. 1. Calodiscus, species undetermined .
Cephalon, «4 (coll. cs-15/L1), USNM 156582,
Figs. 2-6. Calodiscus lobatus (Hall) .

2, Cephalon, 15 (coll. cs-18), USNM 156579, deuetne’ 3, 4,
Silicified cephala, «12. 5, 6, Silicified pygidia, *12 (coll. cs-9a).

USNM 156580, plesiotypes.
Figs. 7-10. Calodiscus walcotti Rasetti, <8. ee:
7, 8, Cephala. 9, Lateral view of cephalon. 10, Pygidium (coll.
cs-26). USNM 156583, plesiotypes.
Figs. 11-17. Chelediscus chathamensis, new species > ae
11-13, Dorsal, anterior, and lateral views of ceetalon, Piro (Call.
cs-9a), USNM 156584, holotype. 14, Cephalon, «7.5. 15, Cepha-
lon, X5. 16, 17, Dorsal and lateral views of pygidium, 7.5 (coll.
cs-9a). USNM 156585, paratypes.
Figs. 18-28. Leptochilodiscus punctulatus Rasetti » ve gh ee
18, 19, Dorsal and lateral views of cephalon, 7.5. 20, 21, Dorsal
and frontal views of cephalon, X10. 22, 23, Pygidia, «7.5. 24-26,
Lateral, posterior, and dorsal views of pygidium, 7.5 (coll. cs-9a).
USNM 156586, plesiotypes. 27, Cephalon (coll. cs-29), USNM
156587, plesiotype. 28, Cephalon (coll. Hubert 63-F24, Elgin Sta-
tion, Quebec), GSC 10565, plesiotype.
Fig. 29. Serrodiscus speciosus (Ford) 3/ eo eye ee
Complete specimen in shale, 3 (coll. cs-24b), USNM 156592,
plesiotype.

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45

46

48

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 3

LOWER CAMBRIAN TRILOBITES

SMITHSONIAN MISCELLANEOUS COLLECTIONS

LOWER CAMBRIAN TRILOBITES

VOL. 152 NO. 4, PLATE 4

PLATE 4

Figs. 1-8. Serrodiscus spinulosus Rasetti :

1, Cephalon, 5. 2, Portion of same cephalon, share ing aneichlatae
ridge, X10. 3, Cephalon, &7.5. 4, Unusual pygidium lacking axial
spine, X5. 5, Pygidium with axial spine, &5. 6, 7, Dorsal and
lateral views of pygidium, <4 (coll. cs-9a). USNM 156593, plesio-
types. 8, Cephalon, 7.5 (coll. cs-17/L1), USNM_ 156594,
pleisotype.

Figs. 9-12. Serrodiscus latus Rasetti . ae te ae

9, 10, Dorsal and lateral views of ceubalea <5. Lie, Pyeidia:
7.5 (coll. cs-9a). USNM 156595, plesiotypes.

Figs. 13-17. Serrodiscus griswoldi, new species. :

13-15, Lateral, dorsal, and anterior views of cephalon, x4 (coll: cs- 4),
USNM 156596, holotype. 16, 17, Lateral and dorsal views of
pygidium (coll. cs-4), USNM 156597, paratype.

Figs. 18-20. Eodiscidae, pygidium no. 7 . i a oe

18, 19, Dorsal and lateral views of silicided py divi, x75. 20, Lat-
eral view of incomplete, silicified pygidium, 7.5 (coll. cs-9a).
USNM 156605.

Fig. 21. Eodiscidae, pygidium no. 6 .

Dorsal view of specimen, «10 (coll. cs- 17/L1), USN M 156604,

Figs. 22, 23. Eodiscidae, pygidium no, 5 . ete eae. Gege ys

Lateral and dorsal views of specimen, 5 (coll. cs-3/L3), USNM
156603.

Page

50

PLATE 5

Page
Figs. 1-4. Stigmadiscus stenometopus Rasetti . . . a
1, 2, Dorsal and lateral views of pygidium, «3. 3, 4, ‘Dorsatiterat and
lateral views of anterior part of pygidium, 3, showing border spines
(coll. cs-4). USNM 156598, plesiotypes.
Figs. 5,6. Eodiscidae, cephalonno.2. . . . . an Ae
Dorsal and lateral views of silicified specimen, x75 (coll. cs-9a),
USNM 156600.

Figs. 7,8. Eodiscidae, cephalonno.3. . 56
Lateral and dorsal views of specimen, x5 (coli cs- 29), USNM 156601.
Figs. 9,10. Eodiscidae, cephalonno.4. . . . - 0°

Dorsal and frontal views of exfoliated specimen, 5 (coll. cs-9a),
USNM 156602.

Fig. 11. Eodiscidae, cephalon no, 1 . eee
Dorsal view of specimen, 10 (coll. cs- 9a), U SN M 156599,
Figs. 12-15. Oodiscus, species undetermined. . . w) S50 ees

12, Pygidium, 10 (coll. cs-3/L2), USNM 156588. 13, Pygidium,
7.5 (coll. cs-15/L4), USNM 156589. 14, Pygidium, «15 (coll.
cs-18), USNM 156590. 15, Pygidium, «4 (coll. cs-17/L1), USNM
156591.

Figs. 16-24. Pagetides elegans Rasetti . . . 2. oe Oe ros

16, 17, Dorsal and lateral views of cranidium, «5. 18, 19, Dorsal and
lateral views of pygidium, 5 (boulder G-24, Grosses Roches,
Matane Co., Quebec). USNM _ 156618, plesiotypes. 20, Crani-
dium, 7.5. 22, Pygidium, 7.5. 21, Cranidium, 12 (coll. es-
15/L5). USNM 156619, plesiotypes. 23, Cranidium, 10 (coll.
cs-18), USNM 156620, plesiotype. 24, Pygidium, 7.5 (coll. cs-
15/L1), USNM 156619, plesiotype.

Figs. 25-29. Pagetides rupestris Rasetti. . . eee TE

25, 26, Dorsal and lateral views of Te X75, 27, Pygidium,
7.5 (boulder G-24, Grosses Roches, Matane Co., Quebec). USNM
156629, plesiotypes. 28, Pygidium, 10 (coll. ‘cs-5), USNM
156630, plesiotype. 29, Cranidium, «10 (coll. cs-3/L2), USNM
156631, plesiotype.

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 5

LOWER CAMBRIAN TRILOBITES

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 6

18

oP

OFS 7

2 _— as < ge ec Pens,

LOWER CAMBRIAN TRILOBITES

PLATE 6

Figs. 1-10. Pagetides minutus Rasetti. tS Pe
1, Cranidium, 7.5 (boulder O-1, Island of Ove Ghaties), USNM
156621, plesiotype. 2, Pygidium, 7.5 (boulder L-17, Ville Guay,
Quebec), USNM 156622, plesiotype. 3, Cranidium, 7.5. 4, Cra-
nidium, X10. 8, 9, Immature pygidia showing pleural furrows,
<10. 10, Pygidium, 10 (coll. cs-18). USNM 156623, plesio-
types. 6, Cranidium, X10. 7, Pygidium, X10 (coll. cs-3/L2).
USNM_ 156624, plesiotypes. 5, Immature pygidium, 10 (coll.
cs-20), USNM 156625, plesiotype.
Figs. 11-14. Pagetides Iciopygus Rasetti . S.A eee
11, Pygidium, 7.5 (boulder L-17, Ville Car Quebec), USNM
156626, plesiotype. 12, Cranidium, 7.5 (boulder O-20), Island of
Orleans, Quebec), USNM 156627, plesiotype. 13, Pygidium, x12.
14, Pygidium, 10 (coll. cs-3/L2). USNM 156628, plesiotypes.
Figs. 15-18. Pagetides amplifrons Rasetti. oF ib
15-17, Cranidia, x10 (coll. cs-4b), USNM 156632, leanne 18,
Cranidium, 7.5 (coll. cs-15/L1), USNM 156633, plesiotype.
Fig. 19. Hebediscus marginatus, new species ..
Cranidium, 10 (coll. cs-51), USNM 156637, Gelaty pe.
Figs. 20-28. Neopagetina taconica, new species .
20-22, Dorsal, frontal, and oblique lateral views of ‘evar 12
(coll. cs-9), USNM 156634, holotype. 23, 24, Dorsal and lateral
views of pygidium, «12. 25, Pygidium, 12 (coll. cs-9). USNM
156635, paratypes. 26, 27, Frontal and dorsal views of cranidium,
«12. 28, Cranidium, 12 (coll. cs-20). USNM 156636, paratypes.
Figs. 29, 30. Dorypygidae, cranidium no. 1 . he a ae
29, Immature specimen, 10. 30, Larger canes fio (COL
es-15/L1). USNM 156670.
Fig. 31. Protypus, species undetermined .
Cranidium, 10 (coll. cs-3/L2), USNM 155673.
Fig. 32. Kootenia, species no.2. .
Pygidium, 5 (coll. cs-26), USN M 156667.

Page

64

600

86

88

83

PLATE 7

Figs. 1-9. Pagetia bigranulosa, new species, X12 . .

1-3, Dorsal, frontal, and lateral views of cranidium (coll. cs-17/L1),
USNM 156606, holotype. 7, 8, Dorsal and lateral oblique views of
pygidium (coll. cs-17/L1), USNM 156607, paratype. 4, 5, Cranidia.
9, Pygidium (coll. cs-3/L2), USNM 156608, paratypes. 6, Cra-
nidium (coll. cs-15), USNM 156609, paratype.

Figs. 10-16. Pagetia laevis, new species, X12 . . . = a

12, Cranidium (coll. cs-26), USNM 156610, ole: 13, Cranidium.
14, Pygidium (coll. cs-26). USNM 156611, paratypes. 10, Lateral
view of pygidium. 11, 15, 16, Cranidia (coll. cs-3/L2). USNM
156612, paratypes.

Figs. 17, 18. Peronopsis, species no. 5 ; eM re

17, Incomplete cephalon, «12. 18, Teepe rahi. 12 (coll.
cs-9). USNM 156560.

Figs. 19-22. Prozacanthoides, species undetermined ee

19, Pygidium, with cranidium of Pagcetia laevis, X7.5. 20, Pygidium,
«5 (coll. cs-26), USNM 156663. 21, Cranidium, 7.5 (coll. cs-
3/L2), USNM 156664. 22, Pygidium, probably representing a dif-
ferent species from those of figs. 19, 20, &7.5 (coll. cs-4b), USNM
156665.

Fig. 23. Corynexochacea, pygidium no. 4

Dorsal view of specimen, 5 (coll. cs-3/L 1), USNM 156677.

Figs. 24-26. Ptychopariacea, cranidium no. 1 ee ee

24, Incomplete cranidium, 7.5 (coll. cs-15/L1), USNM 156690. 25,
Cranidium, 10 (coll. cs-9), USNM 156691. 26, Cranidium, «10
(coll. cs-4a), USNM 156692.

Page

60

61

33

81

90

100

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 7

LOWER CAMBRIAN TRILOBITES

VOL. 152 NO. 4, PLATE 8

SMITHSONIAN MISCELLANEOUS COLLECTIONS

we
aS

<

Bevis

shh
SO

we

~
Saye
Barter

wt

LOWER CAMBRIAN TRILOBITES

PLATE 8

Figs. 1-4. Olenellus, species no. 1, «7.5 . a oes
1, Two cephala, one preserving the external certs 2, Glabella and
pleural lobes. 3, Cephalon (lower), with cephalon of Paedeumias
species no, 1. 4, Fragmentary cephalon showing wide border and
genal and intergenal spines. (coll. cs-15/L3) USNM 156647.
Fig. 5. Olenellus, species no.3. .
Portion of cephalon, &5 (coll. cs- 15/L5), USN M 156650.
Figs. 6-8. Paedeumias, species no. 2. . wer
6, Incomplete cephalon, 7.5 (coll. cs- gan) USNM 156641, 7, Gla-
bella, *5. 8, Incomplete cephalon, «7.5 (coll. cs-15/L3). USNM
156642.
Figs. 9,10. Olenellus, speciesno.2. . 6 ee
9, Incomplete cephalon, 7.5 (coll. cs- aa): USNM 156648, 10, Two
incomplete cephala, 3 (coll. cs-15/L2), USNM 156649.
ace. bii4. fancies, species no. 1 75) 6 ek
11, 14, Cephala (coll. cs-15/L3), USNM 156639. 12, 13, Cephala
(coll. cs-9a), USNM 156640. (See also figs. 3, 18.)
Fig. 15. Paedeumias, species no, 3
Cephalon, 7.5 (coll. cs-9a), USNM 156643.
Figs. 16, 17. Pacdeumias, species no. 6 ,
Incomplete cephala, *7.5 (coll. cs-15/L3), USN M 156646.
Fig. 18. Paedeumias, species no, 4. Pie ate eee Ce fee > Ss
Incomplete cephalon (upper), with cephalon of Paedeumias species
no. 1, *7.5 (coll. cs-9a), USNM 156644.
Figs. 19-21. Paedeumias, species no. 5 ‘
19, 20, Frontal and dorsal views ae venkaliin 5 (coll. cs- 15/L 2). 21,
Cephalon, 7.5 (coll. cs-15/L5). USNM 156645.
Fig. 22. Conocoryphidae, cranidium no. 1
Immature cranidium, 10 (coll. cs-15/L1), USN M 156681.
rig. 23. Atops trilincatus Emmons ey, ar
Rubber impression of cranidium ibened in shle, “3 (coll. H. B.
Whittington, from same locality as coll. cs-24b), MCZ 8536, plesio-

type.

Page

71

72

69

72

PLATE 9

Figs. 1-3. Rimouskia typica Resser .. Uy Oe pasos « eae

1, Free cheek, 5. 2, Cranidium, 5. 3, Cranidium, x4 (coll.
cs-19). USNM 156684, plesiotypes.

Figs. 4-11. Baltagnostus angustilobus, new species.

6, 7, Dorsal and lateral views of cephalon, «18, USNM 156565, Hole:
type. 4, Cephalon, 12. 5, Cephalon, X18. 8, Pygidium, X12.
10, 11, Dorsal and lateral views of pygidium, X12. 9, Pygidium,
x18. USNM 156566, paratypes (all coll. cs-22).

Figs. 12-17, 22. Baltagnostus stockportensis, new species .

12, Cephalon, *18, USNM 156567, holotype. 13, 14, Gaphalet 18,
15-17, Pygidia, 18. 22, Cephalon, «12. USNM 156568, para-
types (all coll. cs-21).

Figs. 18, 19. Gomiagnostus, species undetermined :
18, Glabella, X10. 19, Anterior portion of cephalon, S10 fate cs- 22),
USNM 156555.,
Figs. 20, 21. Grandagnostus’, species undetermined :
Dorsal and lateral views of cephalon, 12 (coll. cs-23), USNM 156569.
Figs. 23-25. Hypagnostus parvifrons (Linnarsson) . . . ... .

23, Cephalon, 18 (coll. cs-22), USNM 156561, plesiotype. 24,
Cephalon, X12 (coll. cs-23), USNM 156562, plesiotype. 25, Cepha-
lon, X18 (coll. cs-21), USNM 156563, plesiotype.

Fig. 26. Peronopsis, species no.4. .

Cephalon, «18 (coll. cs-21), USNM 156559.

Fig. 27. Hypagnostus, species ideeeninen:

Cephalon, 18 (coll. cs-22), USNM 156564.

Figs. 28-30. Ptychagnostus punctuosus (Angelin) . ee

28, Portion of cephalon, X10. 29, Portion of Soniciinnn: ‘10. 30,
Smaller pygidium, «10 (coll. cs-21). USNM 156551, plesiotypes.

Figs. 31, 32. Leiopyge?’, species no.1. . . < che ae

Lateral and dorsal views of cephalon, «10 fenls eal). USNM

156549.
Fig. 33. Leiopyge?, species no. 2 .
Cephalon, 10 (coll. cs-21), USNM 156550,

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35

36

29

oF

34

33

35

28

26

a,

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 9

LOWER AND MIDDLE CAMBRIAN TRILOBITES

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 10

MIDDLE CAMBRIAN TRILOBITES

PLATE 10

Figs. 1-8. Ptychagnostus gibbus (Linnarsson), 7.5 .

1, Cephalon. 5, 6, Pygidia (coll. cs-7/M1). USNM 156553, ein
types. 2, 3, Cephala. 4, Pygidium. 7, 8, Dorsal and lateral views
of pygidium (coll. cs-9d.) USNM 156552, plesiotypes.

ieee: (Peranopsis SUECIES NG. 1. 9c) ao Ge yk es ee

9, Cephalon. 10-12, Pygidia lacking test (coll. cs-9d), USNM
156556.

Figs. 13-18. Peronopsis, species no. 2, 5 :

13-15, Cephala lacking test. 16, 17, Doves ana tateeat views of
pygidium lacking test. 18, Pygidium lacking test (coll. cs-9d).
USNM 156557.

Figs. 19-21. Peronopsis, species no. 3. To al es ea ee

19, Pygidium lacking test, X7.5. 20, Pygidium lacking test, «5. 21,
Small cephalon, X12 (coll. cs-6). USNM _ 156558.

Figs. 22-26. Agnostida, pygidium no, 1 . ee ose ee. at

22, Presumably holaspid pygidium, X18. 23, Presumably meraspid
pygidium, 18. 24, Holaspid pygidium, 12 (coll. cs-23). USNM
156570. 25, 26, Presumably meraspid pygidia, 18 (coll. cs-22).
USNM 156571.

Figs. 27-31. Ptychagnostus, species undetermined . PE ae Cr?

27, Cephalon, %10. 29, Meraspid pygidium, «12. 30, Small cepha-
lon, X18 (coll. cs-21). USNM 156554. 28, Cephalon, 7.5. 31,
Partly exfoliated pygidium, 10 (coll. cs-21), NYSM

Fig. 32. Ogygopsis, species undetermined . . hig!

Pygidium, 5 (coll. cs-7/M3), USNM 156671.

Fig. 33. Oryctocephalus, species undetermined . . .

Small cranidium, «18 (coll. cs-6), USNM 156672.

Fig. 34. Zacanthoides, species undetermined. ;

Cranidium, «3 (coll. es-7/M3), USNM 156662.

Fig. 35. Agnostida, pygidium no. 2 ee ee tuted

Poorly preserved specimen, 7.5 (coll. cs-23), USNM 156572.

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PLATE 11

Figs. 1-14. Bathyuriscus eboracensis, new species . : :

1, 7, Incomplete cranidia, 5. 2-4, Immature Ganiter S1OF a:
Hypostome, 10. 6, Free cheek, 5. 8, 9, Pygidia, 7.5. 11,
Portion of thoracic segment, 5 (coll. cs-21). USNM _ 156655,
paratypes. 10, Pygidium, 7.5 (coll. cs-21), USNM 156654, holo-
type. 12, Largest pygidium found, 5 (coll. cs-21), NYSM, para-
type. 13, Fragmentary cranidium, 5. 14, Fragmentary cranidium,
10 (coll. cs-23). USNM 156656, paratypes.

Figs. 15, 16. Athabaskiella, species undetermined Ce SS

15, Pygidium, 12. 16, Pygidium, X10 (coll. cs-21). USNM
156660.

Figs. 17, 18. Bathyurtscidella, species undetermined on ee Oe

Dorsal and lateral views of pygidium, 7.5 (coll. cs-21), USNM
156659.

Fig. 19. Hemirhodon, species undetermined . .

Pygidium, 7.5 (coll. cs-21), USNM 156661.

Figs. 20-22. Olenoides, species undetermined ep a: all:

20, Pygidium, 7.5. 21, 22, Meraspid pygidia, 12 fer aay.
USNM 156669.

Fig. 23. Olenoides stockportensis, new species. . :

Pygidium, 7.5 (coll. cs-21), USNM 156668, holders.

Figs. 24-29. Centropleura, species undetermined oe ae ae x

24, 25, Fragments of genal spines, 7.5. 26, Fragmentary orale oie
10. 27, Thoracic segment, *5. 28, Pygidium, «12. 29, Gla-
bella of meraspid cranidium, 12 (coll. cs-23). USNM 156678.

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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 11

MIDDLE CAMBRIAN TRILOBITES

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 12

MIDDLE CAMBRIAN TRILOBITES

PLATE 12

Figs. 1-17. Corynexochides? expansus, new species . P
1, Cranidium, 7.5 (coll. cs.-21), USNM 156651, as 2, Crani-
dium, X12. 3, 4, Hypostomes, X10. 5, Cranidium, So DROY ds
Meraspid cranidia, X24. 8-10, More advanced meraspid cranidia,
18. 11, 16, Meraspid pygidia, X24. 12, 17, Lateral and posterior
views of protaspis, X24. 13, Dorsal view of protaspis, «24. 14,
15, Dorsal and lateral views of protaspis, 24 (coll. cs-21).
USNM. 156652, paratypes.
Figs. 18-21. Kootenia, species no. 1 ,
18, 19, Exfoliated pygidia, «10. 20, Exfoliated Paeiaiuay “5. “21,
Pygidium preserving test, X5 (coll. cs- -9d*). USNM 156666.
Figs. 22, 23. Corynexochacea, pygidium no.1. . - - . + + = :
22, Pygidium, 7.5 23, Pygidium, X10 (coll. cs-21). USNM
156674.
Figs. 24-28. Modocia punctata, new species. - - - +» + + + = :
24-26, 28, Cranidia, X12 (coll. cs-21), USNM 156688, paratypes.
27, Cranidium with partly exfoliated glabella, 10 (coll. cs-21),
USNM 156687, holotype.
Figs. 29-31. Bathyuriscus, species undetermined ee ‘
29, Fragmentary pygidium, <4. 30, Fragmentary spcieiidiatn, <4
coll. cs-9d*). USNM 156657. 31, Pygidium, X7.5 (coll. cs-7/M1),
USNM 156658.

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PLATE 13

Figs. 1-7. Pagetia erratica, new species, X12 . :

1, Cranidium (coll. cs-7/M4), USNM 156613, Leleere 2, Crani-
dium (coll. cs-7/M3). 3, 4, Cranidia (coll. cs-7/M4). 5, Py-
gidium (coll. cs-7/M3). 6, Pygidium (coll. cs-7/M4). 7, Py-
gidium (coll. cs-7/M5). USNM 156614, paratypes.

Figs. 8-16. Pagetia clytioides, new species, «12 sts Nbiliy el ne

8, 9, 12, 13, Cranidia. 10, 11, Pygidia (coll. cs-6). USNM 156616,
paratypes. 14, Cranidium (coll. cs-9c), USNM 156617, paratype.
15, 16, Dorsal and frontal views of cranidium (coll. cs-6), USNM
156615, holotype.

Figs. 17-30. Bolaspidella fisheri, new species

17-19, Dorsal, lateral, and frontal views of pe eo 5¢10, USNM
156682, holotype. 20, 21, Free cheeks, X10. 22-28, Various stages
of meraspid cranidia, *18. 29, 30, More advanced meraspid crani-
dia, X12. USNM 156693, paratypes (all coll. cs-21).

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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 13

ee EL
7 : ” ’ y

MIDDLE CAMBRIAN TRILOBITES

SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 152 NO. 4, PLATE 14

1 J 0 BE

Rie TS Sgr Fen
: a <8
Se gt v4

4

MIDDLE CAMBRIAN TRILOBITES

PLATE 14

Figs. 1-6. Meneviella, species undetermined . . roar
1, Cranidium, 12. 2, Fragment of larger epanidina “75. 3;
Immature cranidium, X18. 4, Portion of segment from anterior part
of thorax, 7.5. 5, Pygidium, 7.5 (coll. cs-7/Ml1). USNM
156679. 6, Portion of segment from posterior part of thorax, 7.5
(coll. cs-9d*), USNM 156680.
Figs. 7, 8. Elrathia?, species undetermined .. PO att ee
7, Cranidium, X10. 8, Cranidium, 7.5 (coll. cs-21). USNM
156685.
Figs. 9, 10. Ptychopariacea, cranidium no, 3. rv yl. Tas
9, Cranidium, X12. 10, Cranidium, 10 (coll, cs-21). USNM
156694.
Figs. 11-13. Ptychopariacea, cranidium no.2 . .
Three cranidia, «10 (coll. cs-21), USNM 156693.
Fig. 14. Corynexochacea, pygidium no. 2 . .
Incomplete example, 10 (coll. cs-23), USNM 156675,
Fig. 15. Ptychopariacea, cranidium no. 6

Small, probably immature example, 24 (coll. cs- 22), USNM 156697.

Fig. 16. Ptychopariacea, pygidium no, 1. .
Pygidium, 10 (coll. cs-21), USNM 156699,
Fig. 17. Ptychopariacea, cranidium no. 4.
Cranidium, 10 (coll. cs-21), USNM 156695.
Fig. 18. Corynexochacea, pygidium no. 3 :
Small, probably immature example, «10 feolt:, cs- 23), USN M 156676,
Fig. 19. Ptychopariacea, pygidium no, 2 REA Le ote nl aga -cueee
Pygidium, 12 (coll. cs-23), USNM 156700.
Fig. 20. Elrathina?, species undetermined
Cranidium, «3 (coll. cs-6), USNM 156686.
Figs. 21, 22. Ptychopariacea, cranidium no.7 . .
Two cranidia, 24 (coll. cs-22), USNM 156698.
Fig. 23. Ptychopariacea, pygidium no. 5 ;
Incomplete pygidium, 12 (coll. cs-22), USNM 156703,
Fig. 24. Ptychopariacea, cranidium no, 5 é
Incomplete cranidium, 12 (coll. cs-22), USN M 156696,
Fig. 25. Ptychopariacea, cranidium no, 8
Immature cranidium, 12 (coll. cs-23), USN M 156638,
Fig. 26. Modocia, species undetermined . . ati
Cranidium, 10 (coll. es-21), USNM 156689.
Figs. 27, 28. Ptychopariacea, pygidium no. 4
Two pygidia, X12 (coll. cs-22), USNM 156702.
Fig. 29. Ptychopariacea, pygidium no. 3
Pygidium, *12 (coll, cs-22), USNM 156701.

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