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^B»-

O 8Vi 5 X
A884

00518

OF THE

FOSSIL OSTREIDiE OF NORTH AMERICA;

AN'r>

A COMPARISON OF THE FOSSIL WITH THE LIVING FORMS.

»Y

CHARLES A. ^VHITE, M. D.,

V TH ApPKNWCKa iiY PiioF. ANGELO HEILPBIN anp Mb. JOHN A. HYDEE.

3 INX 18

273

:'ijfer

CONTENTS.

Page.

Letter cf transmittal 279

Introduction 281

Carboniforons 288

J urossiu 289

Cretaceons 290

Larnmic Group 307

Appendix I.— North American Tertiary Ostroic'ie, by Prof. Augelo Ileilprin ... 309

Eocene 309

Oligocouo . ... 311

Miocene 312

Pliocene 314

Post-Pliocene 315

Appendix II. — A sketch of the life-history of the oyster, by John A. Ryder.. . 317

Explanation of plates 334

976

<.l

ILLUSTRATIONS.

Platr XXX IV. — Cnrl><)ii!roroiii» nnd Jurossio Xij

XXXV.— Jiirasaio 337

X.\XVI. — Crctiiceous ;j;)c)

XXXVII. — Crotni;coii.s 341

XXX » III.— Crotnceous ;j.|3

XXXIX.— Crctacodim 34;,

XL. — C'rctiiccous 347

XLI. — C'rotiicooiis 349

XLII. — (,'ii'tucc'oiiH 351

XLIII.— Cretacoous 353

XL.IV.— (;r«tacooii8 3-,5

XLV.— I'rotnccouH 357

XliVI. — CrutacL'oiis 359

XLVII. — Crntaccons 301

XLVIII.— Crotaccoiig 3(53

XLIX. — Cretaceous 305

L.— Cretaceous 3C,7

LI.— Crotnceous 3(59

LII.— Cretaceous 371

LIII. — Cretaceous , 373

LIV.— Cretacoous 37,'-,

LV.— Cretaceous 377

LVI.— Cri'taceous 379

LVII.— Cretaceous 381

LVIII. — Laraniio 3^3

LIX. — Larauiio 380

LX. — Laramie 387

LXI. —Laraniio 389

LXIL— Eoceno 391

LXIII. — Eoceno 393

LXIV.— Eoccuo 395

LXV. — Miocene 397

LXVI.— Miocene 399

LXVII. — Miocene 40I

LXVIII.— Miocene 403

LXIX. — Miocene 405

LXX. — Miocene 407

LXXI. — Pliocene 409

ijXXII.— Post-PIioceno 411

LXXIII.— Living Ostroidm 413

LXXIV.— Livinj; Ostreidas 4ir) •

LXXV.— Living O.streidio 417

LXXVI.— Living Ostreidii? 419

LXXVIL— Living Ostreida) 42I

LXX VIII. — Living Ostreidoj 423

LXXIX. - Living Ostreidaj 405

LXXX. — Living Ostreidaj 437

LXXXL— Living Ostreidaj 429

LXXXII.— Living OstroidiB 431

9tt

z:ri__frr^

LETTER OF TIlANSMm^AL.

Wahiiinoton, June 15, 1883.
Sill: I liL'iewitli transmit to you the inunuseript of a IJeview of the
Fossil Ostrci(la) of North AincriciJ, whiuli, iit your reqiU'st, I hiivo pre-
I)arc(l for your Aumiul Report for 1S,S;{. Tin' work is iicccssarily, to a
hirgc extent, a compilation of material that has already been published,
hut I have attempted to group that material in such a manner as to
convey to the f-eiu-ral reader an outline of the geological histoiy of the
oyster family, and tho connection of the extinct with the living forms
of oysters.

Two important parts of this work have been prepared by Jlr. John A.
Eyder and Prof. Angelo Ileilprin, respectively. Mr. Kyder has prepared
a concise life-history of the common living oyster of tho Atlantic coast,
which he has illustrated by original drawings of his own, and from nm-
terial which ho has prepared in connection with tho United States Fish
Commission.

Professor Ileilpriu has kindly furnished all that portion of the text,
which relates to tho Tertiary and post- Pliocene oysters, which material
is, in great part, tho result of his special studies of tho Tertiary mol-
lusca of tho United States.

All this work is, in accordance with your request, addressed to the
general reader, rather than to the special student ; but in doing this wo
have striven to avoid all scientiflc inaccuracy of statement. Like my
contribution to your report for last year, this is a general review of tho
subject of which it treats, and not a revision or rectiflcation of the forms
which are enumerated and illustrated. Such a rectification is needed,
but it must necessarily bo deferred until another time.

Tho drawings, with tho exception of tho few that have previously
been published, are from the pen of Dr. J. C. McConnell, who also
drew tho numerous illustrations for my contribution to your report for
last year.

Besides tho aid received from Jlessrs. Kyder and Ileilprin, whose work
appears under their respective names, I am also indebted to Mr. W. n.
Dall, of tho Coast Survey, and Lieut. Francis Winslow, United States
Navy, for much information concerning the variation and distribution
of tho living oysters of our coasts.

«70

-■'-m'

280

m;tti:h ok tkankmittai,.

A c(.iiMi.I<.|al.lo iiiiiiiIhm' of 11,,' illiisfiatioiis which arconipiin.v this
mciiK.ir havo been diawii fvoiu N|.c('im..im lu'ldiiKinjr t„ th., United Siafi's
National iMiis.'iiin, by pcrrnissioii of th<> Dim-tor. Ilo Jias also imt-
niitt.'d tlifiiHu of f!...;tn.t.vp(.,s of a portion of those illiistialions whi.-h
were iilrca.ly ongravcd and in jiosst'ssion of tlio aniithsonian Institii-
tiun.

l{i'spc(!tfnll,v Hnbniitted.

4 t

Hon. .1. W. I'o\vi;r.L,
IHmtor of the United Statea Oeoloyical ttiiriwj/.

('. A. WHITE.

A mm\ OF TIIK roSSIL OSTRFIDyE OF NORTH AMRIMOA;
AND A COMI'AKISON OF TliK FOSSIL WITH TIIK LIVIN(!

FORMS.

Hy v. a. WiitTi:.

INTUODIJCTION.

IJcciuise of the firoiit value of Mie coinnioii o.vster ns a fiivorito nrticlo
of food, iM'iIiaits 110 siihjfct connected with fossil coiicliolofry will bo
fouiul to possfss more iiiti-icst to the general reader than that of the Os-
treidu', or oyster family. With this siipposilion in view I propose to
present on the following,' jta^'es a },'t'"t'nil review of that family as it is
rejjresented anion;,' the eolleetioim of fossil remains that have been inado
from North Ameriean Htrata. In addition to a ffeneral statement of the

subjeet, with illustrations of the fossil forma, I shall {five, lor eomparisoii,
n^nires of the lending varieties of the oysters that are now found living
uiiofi oiir Atlantie eoast. 1 had intended to illustra.e the living oysters
of the Paeilie eoast also, but I found it impraetieable to obtain good
siieeiniens of tliem.

While much is known concerning the geological history of the oyster
family within the area that now constitutes the North Ameriean conti-
nent, that history is and will doubtless always remain incomplete. This
incompleteness is due mainly to the fact that among the fossil fori-"- it
is the sliolls aloiio tl 't are availuble for study and to the fnrthe ' ■:■
that these remains a ) usually few and very olten too imiterfect >o ex-
hibit all the characteristics which perfect shells possess. Uesides this,
theextrenie variation in the form and other characteristics of the shell
of the fossil, as well as the living Ostreidrc, renders their separation into
species, and even into genera, a matter of much uncertainly. In the
case of most other bivalve shells there is a ciertain precision of symme-
try that is constant in every individual, from the earliest to the latest
stage of its growth ; but among the Ostreidre, and especially in tho
typical genus (htrca, asymmetry of the shell is the invariable rule. To
what primary cause this a symmetry among the Ostreidic is due, it is
with the present limitation of oiir knowledge, impossible to say ; but it
is certainly a characteristic of the whole family, including all it.* genera
-ind its fossil as well as living forms.
The oyster family belongs to that division of the bivalve mollusca

881

282

FOSSIL OSTREID^ OP NORTH AMERICA.

known as the Monomyaria, or tboso whose shells are closed and held
together by only one adductor muscle, (a)

Other bivalves, such as the common clam, for example, are known as
the Dimyaria, and their two shells are closed and held together by two
adductor muscles. As a rule, the shells of the Dimyaria are symme-
trical, and the individuals of tho various species are constant and regular
in their resi)ec;tive shapes and in their ornamentation. It is also to an
almost equal degree the rule that the shells of the Monomyaria are
asymmetrical, and many of them also exhibit wide indiv'dual variation.
There are, however, uoted exceptions to both these rides; such, for ex-
ample, as those which are presented by the unsym metrical genera Chama
and Miillcria (b) among the Dimyaria, and by the symmetrical Pinna
and some species i)t redcn among the Monomyaria.

Among the sliells that are familiarly known, those which are most
nearly related to tlie Ostreidiu belcug to the genera Anomia, Pcctcn,
Spondyhis, AvicuUi, and Pinna. The most unsymmetrical of these be-
long to the genera Anomia aiiJ Spondylus, but the Ostreidai exceed all
other molluscan shells in asymmetry and extravagant variation.

Different authors have, from time to time, proposed separate generic

namesforcertainmoreorlessdistinctgroupsofformsamongtheOstrcida;,
the greater part of which I regard as not even of subgeneric value. Some
autliors,on the other hand, reject all generic distinctions of the family
Ostreidaj as it is presented in this memoir, and refer all the species to
one and the same genus, the genus Ostrea of Linnaeus. While it is no
doubt true that among the fossil Ostreida;, intermediate forms may be
selected, which will closely unite all the groups of forms for which sepa-
rate generic names have been proposed, it is rega tied as expedient, if
not actually necessary, to recognize among them at least two genera
besides the genus Ostrea proper, and also one subgenus of the latter.
These two genera and the subgenus referred to are recognizable only
among the fossil forms, and only the genus Ostrea proper is recog-
nized among the Ostreidae now living in North American waters. Fur-
thermore, although a considerable number of species of Ostrea have

a In Mr. Ryder's article, on following pages, this muscle is described, and is also illus-
trated in the fignrcs on Plato LXXIII. Its place of attacbment to tbo sli^ll is a con-
spicuous feature of tbo inner surface of each valve, as may bo seen by referring to those
figures on tbo accompanying plates wbich represent the inner surface of the shells.

6The genus MUlleria is a strangely modified group of the Uuionidio, or fresh-water
clams. It is the shells of this genus, together with those of the related genus Aethena
(the former living in South American, and the latter in African rivers), that have been
called fresh-water oysters. In their habits of growth and in their forms the shells of
these two genera are suprisingly like those of true oysters, but they plainly do not
belong to the Of,treidio. MUlleria is said to possess no trace of the anterior adductor
muscle in the adult and fixed state, in which respect it still further siuiulates the
true oysters. Hut both of the adductor muscles arc present iu the young state and
the shells are then also cqnivalve and symmetrical, like those of ordinary Uniones.
Like them, the shell of MUlleria is also free in the young state.

irnmt.l

INTRODUCTORY REMARKkS.

283

been proposed among the living Ostreidte of North America by different
anthors, it is now a serious question whether tliere is really more than
one species of oyster now living in the Atlantic waters of North America
Those of the west coast of North America are not so well known, but
at present three or four species are recognized there by the different
anthors who have studied them.

The shells of the Ostreidre are inequivalve; that is, the two valves
which, like those of all other true bivalve mollusks, are right and left
respectively, arc unequal in shape. The molhisk in a very early stage
of Its existence becomes attached to a foreign object, and the left valve
also becomes attached to that object, leaving the right valve free. Some-
times the left valve becomes attached to the foreign object by the
greater part of its exterior surface ; but sometimes only by the point of
the beak. When the surftico of attachment is large, the shell to a great
extent conforms to the surface upon which it is attached; and such
shells are necessarily irregular in shape. When the surface of attach-
ment is sr ill, the shell is more regular in shape, but in no case are the
valves wholly regular.

The three genora that are recognized in this memoir, and which have
already been relcrred to, are Exoqyra, Gryphwa, and Ostrca, and the
subgenus of the latter is Aleclryonia. (a) Exogyra costata, Say, may be
taken as the typo of this genus, amlE.forniculata, White, asaii interme-
diate form between Exogyra and Oryphwa. The former is represented ou
Plates LVI ard LVII, and the latter on Plate LII. The shells of
Exogyra are usually more regular in shape than those of any other
genus of the Ostreida;, but, as already stated, they are never wholly
regular, and they are often much distorted. The left or under valve is
always much the deeper, and the right or upper valve is usually flat.
The beak of the lo , - ^-aive is always turned strongly to the rear, lb) and
It 18 usually more or less spiral. The inconspicuous beak of the upper
valve also partakes of this deflected or spiral character. The shells of
Exogyra are also, as a rule, more massive than those of any other of
the OstreidiB. This is especially true of the lower valve,' which in
E. costata and E. ponderosa sometimes reaches an inch and a half in
thickness of solid shell substance. The genus Exogyra was a widely
differentiated one in the Cretaceous period, within tlie region that now
constitutes North America. It was not only represented by a consider-
able number of species, but those species embraced a wide variation of
form, as may be seen by reference to the figures that represent them on
the accompanying plates.
The genus Gryphwa is not so well represented in North American strata

rtThe specicB which Conrad proposptl to group nnder tho generic name of Grvpht-
oUrea I regard as not l.eing even subgenorically distinct from Oitrea proper. See re-
marks nndor the head of Oatrea vomer on a following page.

iThat is, to the left hand as one looks down upon the cavity of the valve, the hinee
border being away from tho person.

1 *,

284

FOSSIL OSTREID^ OF NORTH AMERICA

as Exogyra, and not more than two or three M-ell-»leflncd species are
known there. Of these, Gryphaa pUcheri, Mortc u, which is illustrated on
Plato XLIX, may be taken as the type. The beak of the lower valve of
Oryphaa is usually strongly curved upward nearly in the plane of tho
median line, and as a rule not much deflected either to the right or left.
The upper valve is like that of Exogyra, flat, or even slightly concave,
and its beak inconspicuous and not deflected or 'oilcd. •

The American species of Gryphaa are very variable, and it is often
diflicult to say in what particulars many of the specimens differ from
Ontrea proi)er.

The common living oyster of the Atlantic coast, Ostrea virginica, fig-
ures of different varieties of which are given on Dates LXXIII to
LXXXII, niiiy be taken as typical of tho genus Ostrea proper, altliough
several of the fossil species are equally typical of that genus, as may bo
seen by reference, for example, to Platos XXXVI and LX. All the
living Ostreidre of North America belong to the genus Ostrea proper;
all other genera and subgenera of tho family having become extinct.

The earliest known species of the family, which are of Carboniferous
age, belong also to the typical genus. Exogyra and Grypheca were ap-
parently introduced in the Jurassic period, ya) flourished during the Cre-
taceous period, when the great oyster tau.iiy culminated ; and both those
genera became extinct with the close of the Cretaceous period. But
unlike those more differentiated forms just mentioned, Ostrea proper be-
gan its existence before the close of Paleozoic time and h ~.s also out-
lived both of its kindred but more differentiated genera. The subgenus
Alectryonia was introduced with Grypheca and Exogyra, but it survived
them only one geological epoch, when it .also became extinct.

The remains of the earliest known oysters, as has already been stated,
were found in Carboniferous rocks. Professor de Koniuck described
Ostrea nobilissima from the Lower Carboniferous of Belgium, .and de
Verneuil described 0. materctila from the Permian of Russia. Prof. A.
Winchell described 0. patercula from the Lower Carboniferous of Iowa,
but no other trace of the family has been discovered in any other rocks
of the Carboniferous ago in North America. It is quite clear, however,
that the oyster existed through the whole of that a^,e, but it is also quite
clear that it was never so abundant in that age as it became in the next,
and as it remains to the present day.

Fossil oysters are not unknown in the Triassic rocks of Europe, but
none have yet been found in North American strata of that age. In the
Jurassic strata of this continent tho family is only feebly represented,
at least as compared with those of the Cretaceous period. Only one
species of Gryphwa and three epecies Oi" Ostrea liave been published

a Exogyra is known in Kiirnpcnn Jurassic strata, but in Xortli America no sporiosof
that genus is known in any strata earlier tliau tliose of tlio Crefaccons period. Tliero-
foro in our studies of tbo Nortli American rocks we regard Exogyra as distinctively
characteristic of tho Cretaceous period.

WIIITI]

INTRODUCTORY REMARKS.

285

from tho Jurassic rocks, oiio of the latter belouging to the subgenus
Alcctrijonia.

It was in the Cretaceous period, as already mentioned, that the oyster
family reached its culmination. At that time not only was there a great
abundance of individuals, the remains of which are found in almost all
the fossiliforons strata of that period, but there were liviug then a greater
number of specific and generic forms than had ever existed before, and
greater than have existed since. That is, the Ostreidse not only became
generally prevalent and abundant in the marine waters of this part of
the earth at tliat time, but the whole family then reached a greater de-
gree of vai iition as regards speciQc and generic form and feature than
it has ever possessed at any other period.

Two facts in tliis connection seem to be not a little remarkable. First
the oyster family, which was an inconspicuous one among the mollusca
up to the beginning of the Cretaceous period, then assumed, with ap-
parent suddenness, a conspicuous position as regards general distribu-
tion, numbers of individuals, and wide diffeientiation of species and
genera. Second, at the close of the Cretaceous period this differentia-
tion was suddenly contracted to even narrower limits than it possessed
at the beginning of the r,eriod, although the family still remained a
conspicuous one as regards wide distribution, and numbers of individuals.
The abundance of oyster-life now existing in North American waters
is apparent, when one considers the fact that with the present state of
the art of preserving fresh foods, and the facilities for rapid transporta-
tion, the oyster has become a common article of food all over our country
inland, as well as upon our coasts. It seems certain, however, that the
aggregate of oyster life during the Cretaceous period was much greater
than it is now. If there had at that time been human beings in ex-
istence to whom molluscan food would have been acceptable, the flesh
of Exogyra and Gryphwa would, no doubt, have been as palatable as
that of the true oyster. Of tho latter, however, there has been no de-
ficiency since at least the middle of Mesozoic time ; and their flesh was
without doubt, in every way identical with that of living oysters.

Althougn the Ostreida;, as a family, culminated in the Cretaceous
period, different species of the genus Ostrca proper were abundant in
Tertiary time ; that is, in the period immediately following the Creta-
ceous. Certain of these species also reached a larger size than that of
any which are known to have existed before or since, although some
overgrown examples of Ostrea virginka that have been found upon tao
'3oast of Maine are reported to be nearly a foot and a half long.

Tho so called fresh-water oysters of certain South American and
African rivers have already been referred to, and \\, has been shown
that they are not true oysters. In tho oyster trade also the terms "salt-
water oysters " and " fresh- water oysters " are used. The so-called fresh-
water oysters of the dealers are true oysters, but they do not come from
waters that are entirely, but only comparativelv fresh. True oysters

286 FOSSIL OSTREID^ OP NORTH AMERICA.

cannot live in waters that are not more or less saline. It is a fact, well
known to the trade, tbat great destruction of tbe oyster beds is liable
to occur at and near tbe mouths of rivers dnring times of high and long-
continued freshets in the rivers, by which an unusual quantity of fresh
water is passed over them. Lieut. Francis Winslow, U. S. k, of the
United States Fish Commission, has furnished me the following figures
indicating the range of specific gravity from distilled water to that of
the oi)en sea, and also the minimum of that iu which oysters will live.

Specillc gravity of opon-sca orator 1. 027

Speeiflc gravity of the fruHlicst waters in which oysters live 1. 010

SpeeKic gravity of distillcil water 1.000

In giving the minimum specific gravity of waters in which oysters will
live, Lieutenant Winslow does not mean to say that oysters immediately
die when i)laced in fresher waters, but he cites authorities to show that
the density of water cannot fall below 1.010 for any pro tracted period
without destroying the oysters that may have previously lived in it.

It should be remarked that the specific gravity, as above given, is not
liecessarily an absolute indication of the proportionate itmount of com-
mon salt iu the water indicated, but it is approximately so. There are
other substances held iu solution in all sea and baj waters which, no
doubt, have much infiuencc upon the molluscan life they contain ; but
common salt is so largely iu excess of these, that it is usual to consider
that substance alone in such connection.

The common living oysters of our coasts are not unfrequently found
in oi)en sea waters, but iheir chosen habitat is in the waters of bays
and estuaries, which are of less than marine saltness. From the facts
here stated we see that there is a very considerable range of saltness of
the water iu which oysters will thrive.

In the case of the fossil Ostreidte we cannot of course determine the
amount of salt the water contained iu which they lived, but there are
certain circumstances attending thefossilization of those ancient oysters
that tell us with evident approximation the degree of saltness which
characterized those waters. Such a judgment of the character of those
ancient and departed conditions is based upon our knowledge of the
habits of living mollusks in general, and those of the oyster in particular.

For example, those oysters which are found living in open sea waters
are there associated, not with such mollusks as are its associates in
bays and estuaries, but with such as live only in the opensea. If, then,
we find, as we often do, fossil oysters imbedded in strata, mingled there
with the remains of other mollusks which are closely related to such
living forms as are found only in the open sea, we necessarily infer that
the oysters in question had an opensea habitat. Again, if we find, as
we oiteu do, fossil oyster shelle associated in the same strata with re-
mains of molhi!>ks, whose nearest living relatives are found only iu
brackish waters, we necessarily infer that those ancient oysters, like
their kindred which now exist, were capable of living in brackish as

WnlTK.)

INTRODUCTORY REMARKS.

287

well ns in marine waters. These conclusions are all the more reliable
because the other living moUusks referred to are, as a rule, more re-
Btricted than oysters are, to certain degrees of ."fvltness of the waters in
which tiioy live.

Reasoning from such facts as these, it is inferred that the fossil gen-
era Exorjijra and Gnjplicca were denizens of the open-sea; tiiat is, of the
numerous species of these genera that have been discovered in the rocks
of various parts of the world, none, so far as I am aware, have been
found associated with such otlier fossil forms as indicate a brackish- water
habitat, but all their associates indicate that they were denizens of
marine watcr8.(a) The typical forms of Ostrea, on the contrary, while
they occur abundantly in strata of diflerent periods, mingled with ra.srino
associates, have been found also abundantly associated with other mol-
luscan remains that we are compelled to regard as indicating a brackish-
water habitat. Therefore we infer that the various species of the genus
Ostrea proper have always been capable of living in both marine and
brackish waters.

The geology of North America furnishes a most remarkable example
of an abundance of brackish-watar oysters during one of its geological
periods. In that period, now known as the Laramie, and which imme-
diately succeeded that in which the uppermost of the marine Cretaceous
deposits were made, there existed the most remarkable inland sea Miat
the earth has ever known. Its most southern limit, as at present known,
is in Mexico, and its most northern in British America. Its fossil mol-
luscan fauna shows that, like the existing Caspian, the waters of that
sea were not of marine saltuess, but brackish and fresh, or nearly so, in
different parts and at different times respectively. Its present known
molluscan fauna was illustrated in the report of the director for last
year. Among its molluscan remains there is an abundance of oyster
shells, which are found at isolated localities throughout that great for-
mation. The presence of these shells, occurring as they do in many of
the layers, shows that the waters in which they were deposited contained
at least enough salt to make them brackish. The absence everywhere
of true marine forms shows Ihat the Jjaramie sea was nowhere and at
no time of full marine saltuess. In the deposits of all that great intra-
continental sea no shells of either Exogyra or Gryphwa, nor any of the
subgenus Alectryonia have been discovered.

All the remains of the oj'ster fttmily which that great formation has
yet furnished belong to the genus 0.itrea proper. These facts are un-
derstood to indicate that the first named generic forms, as already in-
timated, were not c-.pable of existing in any waters that were not of full
marine saltuess, while Ostrea proper throve abundantly in brackish

o It is possible that these genera nlso entered the estuaries that existed while 'hey
flourished, anil that a knowledge of the fact has escaped ns because estuary deposits
of former geological ages are so rarely discovered. It is true, neverthuless, that the
OstrcidoB of those genera flourished abundantly in association with moUusks and
other animal forms that are characteristic of the open sea.

288

FOSSIL OSTREIDJE OP NORTH AMERICA.

as well as mnrino waters. In closing these remarks it is proper to call
attention to tlio modern aspect of tlio oysters of the great Laramie sea,
as illustrated on Plates LVIII to LXI.

In the following treatment of the subject of this memoir I shall follow
essentially the same plan that was adopted for the Review of the Non-
Marino Fossil MolUisca in the Report of th Director for last year. A
rcctilication of all the errors that have been made by different authors
in their former publication of the species herein enumerated, is not at-
tempted, bnt a part at least of the most obvious errors will be discussed
or mentioned. Under the head of each geological period in which any
of the Ostreidaj are known to have existed, and under the sub-head-
ings respectively of the three recognized genera, all the species that
have been proposed by different authors will be given in alphabetical
order. The synonymy, at least in part, of each proposed species will
be given in connection with its entry.

CARBONIFEROUS.

It has already been shown to be a well-recognized fact that the oyster
began its existence early in the Ca.bouiferous age, and thfit the species
had at that early period the distinguishing cl- aracteristics of true Oatrea.
It is somewhat remarkable, however, that while the fossil species of the
later periods are, as a rule, represented by great numbers of discov( red
individuals, a sulBcieut number of examples of the three published
species of Carboniferous oysters have not been discovered to give a
satisfactory idea of all their respective specilic characteristics. It is
practically certain that throughout the Carboniferous age the oyster
held a precarious existence, and that it was nowhere and at no timo
abundant until Mesozoic time.

Onr knowledge of the existence of the oyster in North America dur-
ing the Carboniferous age is based upon very slender evidence ; only
one species having yet been recognized, and only one example of that
species having ever been discovered.

Genus Ostrea Linnteus.

Oatrea paterculn Winchell.

(Plato XXXIV, Figs. 1,2.)

The specimen upon which the description of this species was based
was obtained from the Kiuderhook Group of the Lower Carboniferous
strata at Burlington, Iowa. The description, without illustration, was
published by Professor Winchell in the Proceedings of the Academy
of Natural Sciences of Philadelphia for 18C5, page 124. The figures of
the shell, which are given on Plate XXXIV, are copies of Professor
Winchell's unpublished drawings.

WIIITI.)

JURASSIC OSTREIDiE.

289

JURASSIC.

It has already been stated that no examples of tlio Ostreidie have
been found in any of the Trinssic strata of North America. This dcfl-
cieuey makes a great hiatus in the geological history of the family,
between the Lower Carboniferous and Jurassic periods. It is probable,
or even practically certain, that members of the oyster family existed
in North America during the Triassic period, but no direct evidence of
it has yet been obtained. One reason at least for the absence of such
evidence is the great paucity of organic remains of all kinds in the
Triassic strata of this continent.

The slight extent to which the Ostreida) .".-e represented in the
Jurassic strata of North America, as compared with .ho Cretaceo'.s
strata which overlie them, is perhaps largely duo to a similar cause.
That is, the molluscan fauna of the Jurassic period is only feebly repre-
sented in North American strata, compared with lihe faunaj of other
periods, and of the same period in other parts of the world. Still, con-
sidering the geological history of the oyster famuy as a whole, as it is
now known, the lack of an abundance of its remains in the American
Jurassic strata is probably due largely to the fact that the family had
not yet reached its full development.

Four species only of the Ostreidce have been found in North American
Jurassic strata, but the genus Qrypliaa appears among them, besides
typical Ostrea and the subgenus Alectryonia.

Genus Ostbea Linnaeus.

Ostrea engelmanni Meek.

(Plate XXXIV, Figs. 3, 4.)

This species was originally published by Mr. Meek in the Proceedings
of the Academy of Natural Sciences of Philadelphia for 1860, page 311.
It was afterwards republished with woodcut illustrations in Paleontol-
ogy of the Upper Missouri, pages 72-74. This is a well-marked species
of typical Ostrea; but it is rare, only a few examples of it, mostly imper-
fect, having ever been discovered. These were found in what is nr -'
the eastern portion of Wyoming Territory, but which was a portion of
Nebraska Territory at the time the species was first discovered.

Ostrea strigilecula White.

(Plate XXXV, Figs. 9, 10, 11.)

At almost all localities in Wyoming, Colorado, Utah, and Idaho where
the Jurassic rocks are found to be fossiliferous, the shells of a small oys-
ter are to be found. They are usually imperfect, both by fracture and
also by corrosion or wave-attrition. The oest examples I have seen are
3 INT 19

^i',

290

FOSSIL OSTREID^ OF NORTH AMEIIICA.

described and figured in Reports of United States Explorations and
Surveys West of tlio lOOtli Meridian, Vol. IV, p. 103, Plate XIII, Figs.
3, a, b, c, d.

This Hliell is sometimes found associated with Oryphaa calceola, var.
ncbrascensh; and some of the more capacious examples so far approach
that species iu form as to suggest the possibility that 0. atrigilecula
may really be a variety of the Oryphaa, with which it is sometimes
found associated.

Ostrea (Alectryonia) proeumbtna White.

(PlatoXXXV, Figs. 6,7,8.)

Only a few examples of this species are known, and these are all im-
perfect. The best of them are here figured for the first time. They
were discovered in Northwestern Colorado, and described in Powell's
Report on the Geology of the Uinta Mountains, page 93.

Genus Gryph^a. Lamarck.
Onjphaa calceola Quenstedt, var. nebrascensia Meek & Hayden.
(Plato XXXV, Figs. 1, 2, 3, 4, 5.)

This American representative of the European Qrypliaa calceola is not
abundant in our Jurassic strata, but it has been found at a considerable
number of localities in the great Rocky Mountain region. As already
remarked iu connection with Ostrea atrigilecula, the typical forms of tliia
species, although they have all the characteristics of Gryphwa, are found
associated with intermediate and transitional forms that can, with pro-
priety, hardly be separated from the Oatrea. The species in question is
f'.ily described by Meek & Hayden in Paleontology of the Upper Mis-
souri, pages 7-t-7C. Five woodcut figures of it are given there, which
are reproduced on Plate XXXV.

The geographical distribution of this form is considerable, examples
of it having been found at distant localities in Wyoming and Idaho.
The first discovered American specimens, as the name implies, were
found in what was then a part of the great Territory of Nebraska; but
it is not likely to be found within the limits of the present state of Ne-
braska. Although specific limitation among the Ostreida is often so
difiicult to determine, I think it would not be unreasonable to regard
this form as fully distinct from the Euj^opean one of Quenstedt.

CRETACEOUS.

The difficulty of discriminating and defining species, even among the
living Ostreidae, has already been referred to, and this difficulty is ftir
greater iu the case of the fossil forms. This fact will be obvious to any
one who scans the following annotated list, and the accompanying illus-

WlllTI.J

CRETACEOUS.

291

trations of Cretaceous Ostroidre. While a considerable number of tlie
names which are given in the following list are shown to be synonyms,
or to represent spurious species, it is probable that some of those which
are given as representing true and distinct species, ought really to pass
into the list of synonyms. Much work needs to be done by a compe-
tent student, upon the North American fossil Ostreidaj, especially upon
those of the Cretaceous period. The utility of treating the fossil Os-
treida) upon the basis of definite specific diagnoses is becoming more
and more questionable; and I am convinced that a more general treat-
ment of the subject will, in the future, be the more rational.

Genus Ostbea. Linnieus.
Oatrea americana Deshayes.

See Exogyra costata Say, on a following page, with which it is svnonv-
mous. ''J

Oatrcc anomiwformia Eoemer.

Professor Eoemer described this form as a species of Oatrea, in Kreide-
bildungen von Texas, page 75, Plate IX, Figs. 7, a, b, c, d, e. The in-
terior of Professor Pvcemer's shell is not known; but in external charac-
ter it is so closely like certain known forms of Anomia that 1 believe it
to belong to that genus. It is, therefore, not considered in this memoir.

Oatrea anomioidea Meek.

(PlatoXXXIX, Fig8. 4, 5.)

Mr. Meek described this form without illustrations in the annual re-
port of the United States Geological Survey of the Territories for 1872.
It was afterward illustrated by myself in that series of reports for 1878'
Plate XI, Figs. 4 and 4 a. Those figures, as well as those which illus-
trate the species on Plate XXXIX, are drawn from Mr. Meek's type
specimens.

Oatrea appreaaa Gabb.

(Plato XXXIX, Fig. 9.)

The form published by Mr. Gabb under this name is probably identi-
cal with his 0. idriaensia. This view is suggested, both by the close
similarity of the two forms and the fact that both are reported to come
from one and the same formation, the Tejou Group of California. The
difference between them is certainly no greater than it is between cer-
tain of the varieties of the living Ostrea virginica, as may be seen by
referring to the figures on Plates LXVII to LXXXII. Some geologist*
and paleontologists, notably Professor Heilprin, contend, and with much
apparent reason, that the Tejon Group ought to be referred to the Ter-
tiary period and not to the Cretaceous. For the present, however I
leave this species with the Cretaceous fauna, where Mr. Gabb placed' it

292

F0881I. OhTKEIDili OF NOUTII AMKUICA.

lu tliu rulooiitolotty of CiililoriiiH, Vol. II, pajjo UOS. Tlie illuMtratioii
wliicli is ffiveii on Tliito XXXIX \h copied from Imh fiyuro on Phite 34,
rif,'. t, of till! volnni i'(|nott'(l.

Ontrvn hdla ' lonrad.

(Pliilo XXXIX, Fljf. 0.)

This Nniall sitt'ciivs was publJHliod by Conrad in tlic report of tlio
United States and Mexitran Itoiindary Survey, Vol. I, p. ir»(i, Plato X,
Fiys. ■», rt, h. It is probably too closely like tlit form which was named
(Mrm clqiantula by Dr. Niswberiy to be regarded an a distinct species.
See remarks under the head of that name on a followinf,' paye.

Oitrea hiHarinjoMa Shnmard.

In his Monograph ie du (lenre Ostren, page GO, Professor Coquand
gives the name of "O. heUariKjnmi Shnmard.'' I am not ac(iuainted with
the publication of any oyster by that imme. It is probably a misprint
or a suppositition for O, hdlipUcata Shumard.

Oatrea helUitlicata Slnunanl.

(Plato LXXVIII, Figs. 1, y, 3.)

Dr. Shumard described this handsome species without figures in the
Transactions of the Saint Louis Academy of Science, Vol. I, page fiOS.
I afterward ])id)lished a description of it with figures in the Aninud
Report pf the United States Geological Survey of the Territories for
1877, p. 270, Plate IV, Figs. 3, a, h; and Plato 8, Figs. 2, a, h. This
species appears to be quite constant in its form and general ejiaracters.
All the known examples are from Texas.

Oatrca blackU \Vhite.

(Plato XLV, Fig. 1, and Pluto XLVI, Fig. 2.)

This form is of a similar typo with 0. helUplkata, and it is possibly
only a variety of that species. Both foims aro from the Cretaceous
strata of Texas, but I am not awarr that they have ever been found
associated together. 0. hlackii is a !arger and less vontricoao shell and
has coarser plications than 0. hfUipUcata. The former was originally
described and figured in iuc rroceediugs of tho United States National
Museum, Vol. II, page 29b, P.'ate 4, Figs. 1, 2. It was also similarly
published in the Annual Iteport of the United States Geological Survey
of the Territories for 1878, page II, Plate XIV, Figs. 1, a, h: and Plate
XVII, Fig. 4.

Ostrea harrandei Coquaud.

(Plate XLIV, Figs. 1, 2; Plato XLV, Fig. 2; Plato XLVI, Fig. 1.)

This remarkably fiuo species was published in Franco by Professor
Coquand iu his Monographic du Genre Ostrea, page 47, Plate XII, Figs.

Willie. I

CUKTACEOIJS.

I- ». lie states ( Iiiit liJH type NpiTiiiieim were olttuiiit-d from Xow JerHoy,
but so fur as I am awaic no otlicr cxamiilos of tlio siiccics have uvrr
bwii (liscovcml. Tlic, illiistiatioiis of this spfcii's in tliis memoir aro
copies of I'rofesMor Cociiiand'rt ligiiros in the work elted.

Vol.
brief

Ontna breiccri Oabb,

The iijfure j-ive.i under this name in raloontology of California, V(
I, I'late -M, I'lii. 1!»1, is that of an imperfect lower valve, and the bri
si.eeillc description on pa|,'o I'Ot of that volume is not more satisfac-
tory. The figure apparently rei.resents an oyster closely related to O.
coittcilleHMiii, and also to O. wijiminijmmH >^Ieek.

Ostrea bryani (iabb.

This form is brielly described without illustration in the Proceodinyn
of the I'hiladelphiii Academy of Natural Sciences for l.S7(i, page 321.
It is reported us conung I'rom the Cretaceous of Nou- .Jersey.

OHtim carinata (Lamarck) lioemcr.

(I'lutc XLIII, Figs. 1, 2, a, 4.)

This species was originally described from the European Cretaceous,
but Professor Itoemer discovered it among his Texas collections and
published it in K'cidebildungiMi von Texas, i)agc 75, I'late IX, Fig. 5.
Professor Co(pia ad regards the Texas form as O.pectinata Lamarck;
but although it seems to vary somewhat from O. carinata, I am dis-
posed to agree with Professor Hoemer in his determinati».ii. Fig. 1
on Plato X is a coi»y of Professor Koemer's ligure, and Figs. 1>, 3, 4 nr,
drawn from a specimen sent from Texas by Mr. George Stolly, of Austiu.

Ostrea coalvillenais Meek.

(Pluto XXXVI, Figg. 1, 2, 3, 4.)

In the reports of the United States (Jeological Survey of the 40th
Parallel, Vol. IV, page 140, Plate XV, Figs. 10, a, b, c, Mr. Meek sug-
gested this name for an oyster which was obtained from the marine
Cretaceous strata at Coalville, Utah. In aspect and details it is closely
like 0. mjomimicmk, which, however, comts Irom the Laramie Grouj).
(See remarks under Ostrea wyominyensis on a following iiage.)

Ostrea confragosa Conrad.

Conrad described this species from the Cretaceous strata of Missis-
sippi in the Journal of the Academy of Natural Sciences of Philadel-
phia, Vol. Ill (n. s.), page 3L'9. On Plate 34, Fig. 4, of that volume ho
gave one small figure, which does not possess sullicieut character to
give any satisfactory idei. of the species.

294

F088IL OSTREID^ OP NOKTII AMKUI"A,

Oitrea congeata Conrnil.

(Plato XXXIX, FiKH. 11, la, IX)

Perhaps no fossil species of oyster is more common and more widely
diMtrihiited in flie Cretuceous striitu of western North Aincrioii thiin O.
cont/rHta. It is a small shell; and ahnost nlways the lower valve is
broadly attached to some foreign body, notably npon the lurgo shells of
Inoceramm.

OHtrea convera Say.

(Hee anjphaa ve»icularis, on a following page, with which it is re-
garded as identical.)

Oiitrca cortex Conrad.

(Plato XXXVII, FlgD. 3,4.)
The form to which Conrad gave this name was found by the United
States and Mexican Ho 'ndary Commission at " Dry Creek, Mexico."
It is briefly described on page 157 and figured on Plato IX of Vol.
I of the report of that commission. Copies of part of those figures
uro given on Plate XXXVII, but they are unsatisfactory, both upon
zoological and geological grounds. They will serve, however, to add
to the fullness of illustration of the fossil Ostreidio.

Oatrca crenulata Tuomey.

Not the 0. crenulata of Lamarck. (See Oatrca tuomeyi Coquand, a
Cretaceous species ; not 0. tuomeyi Conrad, a Tertiary species.)
Oatrca crenulimargo Eoemcr.

(Plato XLIII, Figs. 8, 9.)

Professor Roemer published this form in Kreidebildungen von Texas
page 70, Plato IX, Figs. 0, a, b. The O. quadriplicaia, afterward pub'
lished by Shumard, is almost certainly identical with this species.
Largo collections of specimens show intermediate forms connecting
those which were described by Professor Roomer and Dr. Shumard, re-
spectively. (See 0. quadriplicata on a following page.)

Oatrea crenulimarginata Gabb.

(Plato XL, Fig. 2.)

This sjtecies is reported from the Cretaceous rocks of Tennessee, and
published in the Journal of the Academy of Natural Sciences of Phila-
delphia, Vol. IV (n. 8.), Plate 68, Figs. 40, 41. Little is known con-
corning its identity.

Oatrea cretacea Morton, Owen.

(See O.franUini on a following page.)

Dr. Morton, in his Synopsis of the Organic Remains of the Creta-
ceous Group, page 52, Plate XIX, Fig. 3, published a species under the

WIIITll

CRETACKOirS.

295

Uiiino of Ontrea crctacm, HiippoHiiiK it to Imvo comt! fiwtii rictaccoim
Bfrittii in Aliiltiirna. It linx hIiico Ih'cii imcprtiiirK'tl that liio Htratu from
vliicli liiH Mp<Tlin«'im wcio olitaiiH'il anu.C TtTti.iiy aiidnot (iivtan-oim
nKc This Npt'cifH Iiuh tlicioloro Itct'ii iiirliKlfd in the list of tin- T<'r(iar.v
OMtrcichu hy I'rofi'Msor llrilprin on a HnliNcqiionf paj{(>. In tlni Hcconil
Kcportof fli.'CJ|.()Ioj;i('al Mnrvi'.v of AikanHas, "IiIi'm VII and VIII, I>r.
Ovycn (ijtnml an oyMlcr from ('ictarcons rocl.M of tiiat Hiato wliirli liu
rcffiTi'd (o the OMtrea octtm-a of Morton. Withont knowin« that they
••uino fn.m dillV-icnt loinnitlonN, Pioft-wMor Coqiiand regarded tli*>m as
loproHcntinK two distinct HpccifH. Thcicfon', in his MonoKiaphiti dii
(icnio Ostiva, paj,'»* M, I'lat.- XXIII, FiKs.rt-10, ho miMitiou.-d and ()»,'•
nicd Dr. Ovvon's form, and named it Ontrea J'ranlMni.

(htrm ilenthuli/cra Conrad.

This is another form (ho publication of whieli Ih very unsatisfactory.
It was described in the .lonrnal of the Academy of Natural Hciences
of Philadelphia, Volumo HI (n. s.), i.aj,'e .iSI. On Plate .'J4 of that vol
nme, Fi>;H. I and 8 are fjiven as illuMtiations of the species, but they are
not of Huch a character as to givo much aid in simcific idcntitlcation.
Mr. Conrad's examples came from the Oretuceous strata of Mississippi.

0$(rea diluviana Linmcus.

(Pinto XL, Vig. I ; rittlo XLI, l'ij{g. 1, a.)

Some interesting specimens of this form were sent to the Smithsonian
Institution some years ago from the Cretaceous rocks of Bell County,
Texas. They seem to bo specifically ideutiijal with the long-known O.
diluriana of LinnaMis. At least they are so nearly like that Kuropeau
species that I do not feel warranted in placing the Toxan form under a
separate name. This shell has tlio toothed margin, and to some extent,
also, the characteristic marginal outline of Aleotryonia, and it ought per-
ha|)s to be ranged under that subgenus.

Ostrea elegantula Newberry.

(Plato XXXVI, FIgg. 5, 6, 7.^

Prof. J. S. Newberry, in his Geological Heport which accompanies
that of Captain Macomb's Exploring Expedition, pago 33, proposed tho
name Ostrea elegantula for a small Cretaceous species which ho found
abundantly in tho valley of Canadian River, but ho gave neither do
scription or figures of it. Professor Newberry has kindly furnished
for this article authentic specimens from his original collection, figures
of which are given on Plate XXXVI. This form is probably identical
with Ostrea bella Conrad, but as I am not quite certain of this, I give
both names a place in this list. Professor Nevberry's reference to his
form was written before the publication of Conrad's description, but his
report was not published until long afterward, in 1876.

29G FOSSIL OSTKKID.E OF XORTII AMERICA.

Ostrea exof/yrclla Cuibb.
'Ml. Gahb piihlisliwl (his form witliont figures in the rrocecdiiin-s of
, tlie Aciidi-niy of Natiinil Si-iciicos of riiilailelpliiii for 1S7U, i»ii-(.r3L>J,
lie reported it from the Crotaccons strata of Georgia, but so far as I
am aware it has not since been recognized.

Ostrea /(thd fit Jlorton.

(See Ontrea hirva Lamarck, on a following page, with which Jlorton's
form is regarded as identical )

Ostrva fro nkliiii Voqimml.

(I'lat.'XXXIX, Fiss. 1, 3, a)
Dr. 1>. D. Owen figured but did not describe this form on Plates YII
and VllI of the Second Keport of Hie (ieological Survey of Arkansas,
and referred it to the (htrca cretacca of Jlorton. (See "remarks under
the head of O. eretacva on a preceding page.)

" Chtrca (jnhhnnna Jfeek I'v- Ilayden."

This name appears in IMeek's Check List of Xorth American Creta-
ceous Fossils, but it is believed that no descrii)tion or illustration of it
has ever been jiublisheiL

Osirea inornata JFeek.

A description and figure of this small form are given by Mr. Jleek
in Vol. IX of the United States Geological Survey of the Territories,
page IL riato X, Fig. 4. The latter is an unsatisfactory representation
of a s])ecies, ami the description fails to convey a dear idea of it.

Ostrea idriaemis Gabb.

(IMatr XXXIV, Fijjs. 7, 8.)

Mr. (".abb described both this form ami 0. apprcssa from the Tejou
Group of California. Under the head of the latter nauu^ on a previous
page I have suggested that 'joth forms probably belong to one and the
same species. 0. idriaoisls is figured by :\Ir. Gabb on I'lates ;?3 and 34
of Vol. II, Paleontology of California, and it is described on page 203 of
the same volume.

Ostrea (Alectryonia) larni Lamanik.

(I'lal.'XLlI.Fi;;.. •.',:!, .1,5, (1,7,8,!).)

This variable siu'cies has i)robably a wider geographical distribution
than any other Cretaceous (Mrea; and it has been km)wn under more
than a dozen si)eeitic names. It is known in various parts of Europe, in
Southern India, and in dillercit parts of the United Stu.'es, esi)ecially
in Xi w .lersey and Alabama.

-Morton in his synopsis jiroposed for three American varieties of this
sliell the three specific names/«/c«^«, nastita, and mcscntcrka.

•«'■»

""""1 CRETACEOUS. 297

Ont>r<t hitcnilis Nilssoii.

Certain authors liavo royurded the Ontmt romcr of JFortoii as idi-nt ical
with tho Kur()i»oaii om (lc'seril)e(l iiiuUt tlu' iiaiiio 0. hitcrttlis by Nii.-soii.
I repinl Mioiii as distinct. (See lenuu ks under the head of Ostmt ronur
on a folio viufi; {)a;;e.)

Ostira UtthiGiihh.

rnder tli s name .^fr. Gabb described a form without iUustialioii, in
tlie I'l-oeeednys of the Academy of Natural Sciences of Philadelphia
for 1S7G, par^e 3l»l. It is reported from the Cretaceous of Georgia.

Ostna litgubris Conrad.

(Pint." 1,1, vu^. :!.)

All the known examples of this si)ecies are so small as to sugfjest that
they may be the young of a larger species; but it seems to bo very con-
stant iu size and in other general characteristics. It is common in cer-
tain of tho Ci'etaceous rocks of Colorado and New Mexico. It was orig-
inally published in the report of tho United States and New ]Mexica'u
Boundary Survey, Vol. I, page 15G, Plato X, Figs. 5 a, h.

Ostrcn lyoni Shumard.
Dr. Shumard published this form from tho Cretaceous strata of Texas,

without illustration, in the Proceedings of tho Boston Society of Nat-
ural nistory, Vol. VIII, i)ago 200. Similar mention has been nuido of
other species which have boon published without illustration. It is dilll-
cult at best to correctly illustrate a species of tho Ostreidio even by tho
use of numerous and well preserved examples; and in tho i)resent state
of i)ublication of the fossil forms it is almost impossible to identify any
species, even a well-marked cue, by a written description only.

Ostrca maUci/ormis Gabb.

(Plato L, Vig. !*.)

Mr. Gabb obtained this species from the Orotaceou.s rocks of Cali-
fornia, and published it with one ligure in Vol. II of tho Paleontology
of that State, page 204, Plato 31, Fig. 272.

It is characterized by wing-like expansions of tho cardiiuil portion,
and seems to bo a well-nuirked species.

Ostrcn mescntericd ]Morton.

(See remarks under the head of Ostrea larva on a preceding page.)
Osfrca mortoni Gabb.

Mr. Gabb described this form as coming from Cretaceous strata, but
Professor Ileilprin regards it as a Tertiary species. (See his remarks
under the same head on a following page.)

^^mmmm

■n

298 FOSSIL OSTREIDiE OF NORTH AMERICA.

Ostrea multiliraia Courad.

(PlatoXXXVIII, Figs. 1,2.)

N"o very perfect cxaiiiplos of tliLs species have been obtained, but it
18 ai)i)arently a well-marked one. Conrad's. types were collected near
the boundary between Mexico and Texas, and publislied in tlie report
of the United States and Mexican Boundary Survey, Vol. I lac- 157
VMeXU,Fig.-<,a,b,c,d. '^ '

Ostrea nas%ita Morton.

This form is regarded as only a variety of Ostrea larva Lamarck. (See
remarks under the latter head on a preceding page.)

Ostrra owenana Shumard.

Dr. Shumard published this form without illustration in the Proceed-
ings of the Boston Society of Natural History, Vol. VIII, page 200. It
was obtained by him from the Cretaceous strata of Texas, Not being
illustrated it seems impracticable to identify it from the description
alone.

Ostrea panda "iilot^on.

Dr. Morton described this form as coming from Cretaceous strata:
but Professor Heilprin regards it as of Tertiary age. (See his remarks
under the same head on a following page.)

Ostrea pandaformis Gixhh.

This species was described by Mr. Gabb in the Proceedings of the
Academy of Natural Sciences of Philadelphia for 1861, page 328. It is
reported to come from the Cretaceous of Mississippi, but not having
been illustrated it seems impracticable to ideutify it.

Ostrea patina Meek & Hayden.

(Plato XLVII, Figs. 4, 5, 6.)

This is a very common yet variable species in the Cretaceous strata
of the Upper Missouri River region. Mr. Meek referred it with some
doubt to the genus Qryplima. It is described and figured in Vol. IX of
the United States Geological Survey of the Territories, page 16, Plates
X and XI.

Ostrea pecuUaris Conrad.

Conrad described this species in the Journal of the Academy of Nat-
ural Sciences of Philadelphia, Vol. Ill (n. s.), p. 329. On Plate 34 of
that volume he gave a single figure of a small shell, but it is too indefl-
nite to be of use in the identification of the species. It is reported to
oome from the Cretaceous rocks of Mississippi.

„,

wiim]

CRETACEOUS.

29S

•I '

Ostrea pellucida Meek & Hay den.

(Plato L, Figs. C, 7.)
This is not the Ostrea pellucida of Defranee 1821, but it is a small
species fioni the Cretaceous of the Upper Missouri liiver region, wliicli
was published in Vol. IX of the United States Geological Survey of the
Torntones, page 15, Plato XXVIII, Figs. 4, a, b. It is probably the
lorin that Dr. Morton supposed to bo identical with his 0. falcata ( =
0. liirm), but it is quite distinct, as was shown by Mr. Meek. It is also
evidently the same form that was described by Meek & Haydea under
tlie name of 0. tramlucida in the Proceedings of the Academy of Nat-
ural Sciences of Pliiladeli)hia for 1857, page 147. Both that form ami
the one they called O. pellucida are reported from the same formation
and same locality, and they are probably identical. A clear specific
characterization has not been given of either of the forms ; but in any
case the name 0. pellucida cannot hold, because it was used long a"o by
Defranee for a different species. The latter name is probably an Inad-
vertent suppositition on the part of the authors for the previously used
name 0. translucida,

Ostrea planovata Shnmard.

Dr. Shumard described this form in the Proceedings of the Boston
Society of Natural History, Vol. VIII, page 201. In the same paper
both 0. lyom and 0. owenana were published among other Cretaceous
lossils from Texas. As no illustrations of either of these species have
been published, and as the type specimens are not accessible, it seems
impracticable to identify them among any collections subsequently

Ostrea plumosa Morton.

(Plate XXXVII, Figs. 5,6.)

Dr. Morton obtained this species from the Cretaceous strata of New
Jersey, and published it in his Synopsis of the Cretaceous Formation
of the United States, page 51, Pate III, Fig. 9. It seems to be a very
variable form, and the figures here given, although they correctly repre-
sent the specimens used, are not very satisfactory.

Ostrea prudentia White.

(Plato XL, Figs. 5, 6.)
The only specimens of 0. prudentia that have yet been discovered
were obtained from the Cretaceous strata of Southern Utah It was
originally published in the reports of the United States Explorations
and Surveys West of the 100th Meridian, Vol. IV, page 171, Plate XIV
Figs. 2, a, b, c, d. '

Ostrea quadriplicata Shumard.

(PlatoXLIII, FiRs. 5,6, 7.)
Under the entry of Ostrea crenulimargo on a previous page it has
already been stated that the form bearing that name is believed to be

I!)

300

FOSSIL OSTRKIDvE OF NORTH AMERICA.

identical with tliis. I'lofessor Eooiiicr iiiid Dr. Slniiniiid olitaiiicd their
res])ective si)eeii:ieii,s lioiii the Cretaceous strata of Texas. Dr. Sliii-
iiiard described 0. qiiadripliaitn in the Transactions of the Saint Loni.s
Aeadeiny of Science, Vol. I, i)afje WIS, without illustrations. 1 after-
ward obtained copies of his uiii)id)]ished drawiufis, ami publislied them
together with others in the Annual IteiKnt of the United States Geolog-
ical Survey of the Territories for 1877, Plate VIII, Figs. ;3, a, h. Copies
of those figures are given on Plate XLllI.

Ontrm wbmla Conrad.

(I'liiro XL, Figs. H, .1.)
Conrad jiublished this form in the Keport of the United States and
^Mexican Boundary Survey, Vol. I, page 150, Plato IX, Pigs. 3, a, h.
His type specimens came from the Cretaceous strata near Laredo,
Texas.

Ostmi (Alcctnjoni(t) sannionis White.

(Plato XLV, Fi-s. :i, 1,5, (I, 7.)
Up to the present time this species has been found only at Coalville,
Utah, where a considerable number of specimens were obtained. It is
a well marked and apparently constant form. It was first published in
Powell's Geology of the Uinta Mountains, and afterward illustrated in
the Annual Keport of the United States Geological Survey of the
Territories for 1877, Plate II, Figs. 2, a, h, c, d, e.

Osfrea soleniscus Meek.

(Plate XLIL Fig. 1.)
This remarkable species is found in the Cretaceous rocks of Southern
Wyoming and the adjacent parts of Utah and Colorado. The typical
examples are very long and slender, sometimes reaching a length of
eighteen inches with a width of only two and a half or three inches.
Associated with these long, slender forms, I have foun I some that are
.scarcely more elongate than ordinary oysters. In , iew of the great
elongation of one variety of the living Ostrca virginica, such, for example,
as is illustrated on Plato LXXXI, I am much disposed to regard these
short fossil forms as belonging to the same siiecies as the slender ones
with which they are associated. Mr. Jleek described 0. soleniscm in
the Annual Report of the United States Geological Survey of the Terri-
tories for 1871*, page 487. I gave two tigures of it in the same series of
reports for 1878, ou Plate XI of that volume.

Osfrea suhalata Meek.

(Plate XXXIX, Fijr. 10.)
The type specimen describe<l by Meek under the name of Ostrca
(Gn/phwontrcK f) stihahita in Volume IX of the United States Geological
Survey of the Territories, jiage la, and figured on Plate 28, Fig. 5, was
obtained from the Cretaceous strata of the Ui)per Missouri River region.
It has not since been su'tisfactorilv identified.

CEETACEOUS.

301

Ostrea subovata Shmimnl.

I3r. Sliiunard biietly described this form iu the report of Marcj's Ex-
ploration of the Ited River of Louisiana, page 193. Ho gave one tiguro
of it on Plate 5 of that volume, but it is too indistinct to bo of any serv-
ice iu the identification of the si)ecies. I suspect, however, that Shii-
niard's form is identical with tlie one I have mentioued ou a previous
page under the name >f 0. diluviana Liu.

Ostrea subspatulata Forbes.

(Pinto XXXVII, Fig8. 1,2.)

The type specimens of this species were obtained by Sir Charles Lyell
in \ew Jersey, and published by Forbes, with two wood-cuts, in the
(Juarterly Journal of the Geological Society of Loudou, Vol. I, page
01. It has since been somewhat unsatisfactorily identified in the Cre-
taceous rocks of the Gulf States, but it has not been anywhere recog-
nized as an abuudaut form.

Ostrea teoticostata Gabb.

(PlatoL.rigs. 4, 5.)

Mr. Gabb reported this form as conung from the Cretaceous strata
of Tennessee and New Jersey. It is published in the Journal of the
Academy of Natural Sciences of Philadelphia, Vol. IV (n. s.), page
403. Two small, unsatisfactory figures of it are given on Plate 08 of
that volume.

Ostrea torosa Morton.

Dr. Morton published a form under this name iu his Synopsis of the
Cretaceous Formation of the United St.ites, page 52, Plato X, Fig. 1.
It is evidently, as Gabb has pointed out, only a distorted example of
Exogyra costata Say. (See remarks under that head on a following page.)

Ostrea translucida Meek & Ilayden.

See renuirks on a previous page under the head of Ostrea iicUucida.
If, as is supposed, this form is ideutical with that which the same au-
thors described under the name of 0. pellmida^ the latter name must give
place to 0. translucida, because it was preoccupied by Defrauce in 1S21.

Ostrea tnomeyi Coquand.

Professor Tuomoy obtained this species from the Cretaceous strata of
Alabama. It has never been figured, but it was described by him under
the name of Ostrea cremilata in the Proceedings of the Academy of Nat-
ural Sciences of Philadelphia for 1851, page 171. This name having
beeu preoccupied by Lanuirek in ISOl, Professor Coquand, iu his Mou-
cgraphie du Genre Ostrea, page 08, gave Professor Tuomey's species
the name of 0. tnomeyi.

Courad seems to have intended to give the name Ostrea tuomcyi to a

i '<

802

FOSSIL OSTREID^ OF NORTH AMERICA.

Tertiary species, but be never properly published it. (See Professor
Heilprm's remarks under the same head on a following page.)

Ostrea uni/ormi^ Meek.

(PlatoXLVIII, Figs. 6, 7.)

lu the report of Macomb's Exploration, page 124, Plate I, Figs. 2 a
h, c, Mr. Meek published a form from New Mexico, which appears to
be a well-marked species; but so far only the type specimen is known.
Ostrea vellicata Conrad.

This species is not satisfactorily known. Conrad described and figured
It in the Report of the United States and Mexican Boundary Survey
Vol. I page 150, Plate XI, Figs. 2, ,, j. j^ joes not perhaps differ
speciQcally from 0. cortex, by the same author, which is figured on the
sauie plate.

Ostrea vomer Morton.

(Plato XLVIII, Figs. 8, 9, 10.)

Dr. Morton published this form in his Synopsis of the Cretaceous
Formation of the United States, page 54, Plate IX, Fig. 5, under the
above name. Mr. Gabb and others have regarded it as identical with
the Ostrea lateralis of Nilsson; but it appears to me to as well deserve a
separate name as many other American forms which resemble European
species. Conrad made it the type of his proposed genus Gryphwostrca.
1 do not, however, regard the characters upon which thatpropcsed genus
was based as even subgenerically distinct from those of true Ostrea.

Genus Guyph^ea Lamarck.
Gnjphaa mucronata Gabb.

This name was proposed by Mr. Gabb in Paleontology of California.
Vol. II, page 274, for the variety of G. pitcheri to which Conrad had pre-
viously given the name G. navia.

Grijphwa mutabilis Morton.

(See Gryphcca vesiciilaris Lamarck.)
Grgphaa navia Conrad.

As above stated, Gabb gave the name 0. mucronata to this form.
Professor Eoemer figured it on Plate IX of Kreidebildungen von Texas
as G. pitchen, and he was doubtless right, as G. pitcheri is a very variable
species, and G. navia is regarded as only a variety.

Gnjphaa pitclieri Morton.

(Plato XLIX, Figs. 1,2,3,4,5,6.)

This is perhaps one of the most widely distributed and most variable
species among the Ostreid* of North America. It was originally dis-

WIIITB.]

CRETACEOUS.

303

covered in the Cretaceous strata of New Jersey, and published by Dr.
Mortou in his Synopsis of the Cretaceous Formation of the United
States. It I js since been recognized in widely separated localities in
the United States and Mexico. Some of the varieties lose the promi-
nence of the beak of the lower valve, and approach an ordinary oyster
in ai)pcarauce. A variety of this species, somewhat common in Texas,
is narrower than the typical form and has a more produced beak to the
lower valve. Conrad gave this form the name of G. navia, as already
mentioned. Figures of it are given on Plate XLIX.

Oryphaa thirsw Gabb.

Mr. Gabb described this as a Cretaceous species, but according to
Professor Heilprin it is found in true Tertiary strata. He regards it
as not generically distinct from the Ostrea, and it will be found on a
following page among the Eocene species under the name of Ostrea
thirsw.

Oryphaa vesicularia Lamarck.

(Plate XLVIII, Figs. 1,2,3,4,5.)
The species which is arranged under this name is a somewhat varia-
ble one. Dr. Mortou published certain specimens of it under the name
of Ostrea mutabilis, and Say published others as Ostrea convexa. These
American forms are now generally regarded as specifically identical with
the long-known European species Qryyhwa vesicularis of Lamarck. It
is found in the Cretaceous rocks of the Atlantic and Gulf States.

Qrtjphwa vomer Morton.

Dr. Morton described this species as a Oryphaa, but I regard it as
not generically distinct from true Ostrea. (See remarks under O^^trca
vomer on a preceding page.)

Genus Exogyba Say.

Exogyra arietina Eoemer.

(Plate LVI, Figs. 3, 4, 5.)
This species is quite a common one in the Cretaceous rocks of Texas
and theadjacent parts of Mexico. It is generally known under the above
name, which was published in Kreidebildungen von Texas, page OS,
Plato VIII, Figs. 10, a, b, c, d, e, but it possibly ought to be called
Exogyra laxa Say. In 182G Mr. Say described a shell under the name of
Delphinula laxa which, from its resemblance to certain si)ecimens of E
arietina, and my lack of knowledge of any other species to which it may
belong, I believe to have been a specimen of the larger valve of this
Exogyra. If I am correct in this supposition, Say's specimen was that of
a fossd nistead of a recent shell, and an Exogyra instead of a Delphinula.
Say 8 very brief and unsatisfactory description of D. laxa may be found

e^-^ss'^-tS^^^^sai^^^^^wrsi*-

^mm>^^^

304

FOSSIL OSTREIDiE OF NOUTII AMERICA.

ou page 150 of Biiine.v'H edition of Say's wiitiuga and Mrs. Say's excel-
lent ligures of it on I'hitc 7 of that volume.

Conrad puhlislied this species under the uanic o{ Exogyra caprina in
the Journal of the ^Vcadeuiy of Natural Sciences of Philadelphia, Vol.
II (n. N.), page 2T^, I'late XXIV, Figs. 3, 4. Koenier's name must
remain, however, because it was previously published, unless tlio name
Exogrjra Utxa Say shall be used.

Exogyra uquila Goldfuss.

(ridtoLIII, Figs. 1, a.)

The 8i)eeimena which are here recognized as belonging to the Exogyra
aqitila of (Joldfuss were sent to tlie Smithsonian Institution some years
ago by Mr. D. A. Walker, from Hell County, Texas. [Jpon comparing
them with the figures given by Goldfuss in his Petrefacta C.ermaniro,
page ;{(J, Plate 87, 1'ig. .{, no features appear to me upon which a specific
difference can be based. I am not aware tliat this species has before
been recognized in Ameri(!an strata, but various authors have reported
it from different i)arts of Europe and from both Northern and Southern
Africa.

Exogyra columbcUa Meek.

(Plato LV, Figs. 5, (i.)

This small species of Exogyra has hitherto been found only in Southern
Utah and the adjacent parts of New ^Mexico, where it is sometimes found
assocmted with E. lariiiscula Koemer, which species it resembles in size.
Itwas published by myself in the reports of United States Explorations
and Surveys west of the 100th Meridian, Vol. IV, page 174, Plate XVII,
Figs. 3, a, h, e,(l. I there regarded it as a small variety of E. cantata,
and gave it the variety name of fltminis. In the same year Mr. Meek
published this form under the name of E. columbella, in the Report of
Macomb's Exploration, page 124, Plate I, Figs. 3, «, 6, c, d.

Exogyra costatc Ssiy.

(Pl.ito LVI, Figs. 1, 2; Plate LVII, Figs. 1, 2.)

This is one of the most common and characteristic as it is one of the
largest species of Exogyra that are found in the Cretaceous rocks of the
United States. It is especially characteristic of certain strata in the
Atlantic and Gulf States, and also in Mexico. It is usually quite con-
stant in its form and in the costate character of its surface, but in the
latter respect it is sometimes variable. Indeed, some authors regard
Exogyra pondcrosa Eoemer as only a variety of E. costata, dilfering only
in the obsolescence of its costre. This feature is so constantly present
in the one form and absent in the other that I prefer to regard them as
representing distinct species.

W^^

WIIITI.)

CRETACEOUS.

I .

Exogym Jimbriafa CouraiL

Thi8 proposed species is really nnwortliy of notice, because its original
description was based upon only a single npjier valve, which is i)robably
that of a small example of Exogyra ponderosa. Conrad i)nblished it in
the Report of the United States and Mexican Moiindary Survey, Vol. I,
page 154, Plate VII, Figs. L', a, b. Adding still further to uniieces.sary
synonymy, the name is, by typographiiial error, given as E.foluwca on
Plite 7, Vol. I of the United States and Mexican Houndary Survey.
Furthermore, Coquaiid, in his Mcmographie du (lenre Ostrea, i)age 00,
jiroposed to change Conrad's supposititious name to 0. Habjiiiibriata.

Exof/yra /orHiciiIafa White.

v-liiti^ ur, riKH. 1,2.)

Tlie gnidation of the genus Gryphwa, which has before been referred to, is
exeinpiilied by this species, wliich might with equal proimety be referred
to cither genus. The jHincipal distinguishing cliaracteiistic of Exoyyra
I have taken to be the lateral deflection aiul greater or less curvature
01 the beak of the lower valve. The full develoinnent of this feature is
shown in sucli forms as E. costala and E. Iwi-iimcula, and the minimum,
in the species heading this i)aragraph. So far as I am aware Exogyra
forniculata has been found only in Texas and the adjacent parts of
Mexico. It has often been coniounded with the variety of Grypluea
pitcher i to which Conra<l gave the name G. navia. It was originally pub-
lished as a distinct 8i)ecies in the Troceedings of the National Museum
Vol. II, i)age293, Plate IV, Figs. 3, 4 ; and subsequently in the Annual
Report of the United States Geological Survey of the Territories, i)age
13, Plate 14, Figs. 2, a, i.

Exogyra fragosa Conrad.

This form is i)erhaps only a variety of E. ponderosa, but it was pub-
lished as a distinct species by Conrad in the Report of the United States
and Mexican Boundary Survoy, Vol. I, Plate VIII, Figs. 2, a, h. It
was obtained from Cretaceous strata of Texas.

Exogyra interrupta Conrad.

Mr. Conrad published a form under this name from the Cretoceous
strata of Mississippi in the Journal of the Academy of Natural Sciences
of Philadelphia, Vol. Ill (n. s.), page 330, Plate34, Fig. 15. The tigure
is very unsatisfactory, and aiii)arently leprcsents a young and small
example of the lower valve of a si)ecies like E. wincheili.

Exogyra Imviuscula Roemer.

(Plato LII, Figs. 3, 4, .'■..)

Professor Roemer published this species from the Cretaceous strata of
Texas in his Kreidobildung von Texas, page 70, Plate IX, Figs. 3, a, b,
3 INT 20

30(!

ro.-SIl, OSTlfKIPA; OK NOIiTir AMKKIOA.

c. 11 liiiH also lu'cii foiiiiil ill \c\v Mexico, and in (lie State of Nnovo
Leon, .Mexico. It is a well marked and not very variable Npecien.

EdiiflUni M((ll(in>iiiiiiiii d'Oiliii^ny.

Conrad, in tlie Kepoit ot' tlie United States and Mexican Ilomidiiry
Survey, relcncd certain spcciincns to tliis species tliat are Npecilleally
identical willi tlie loriii tliat Prolessor I^eiiicr dcsciiltcd under tlie nanio
of i:.ni;ij/ni tvjatiii. (See icniaiks under tliat liead in a loilowiiij; para-
Kiapli.) I( is a soiiiewliat coiniiion lonii in the Cretaceous of Texas and
tlie adjacent jiarts of .Mexico.

L\riifii/r(t pJivdIa raniarck.

It isdoiihlfnl wlietlier tliis species exists in North American rocks.
Certain antliors liavo placed siieciinens nnder this name wliieh I helievo
to belon;; to the 11. icvauii of Ktemer. (See remarks nnder that head in
a followiii;,' paia;;rapli.)

Exofiyra ponderoaa Rcumor.

(I'latL- I,, I'iKs. \,->, :i.)

This massive form is eommon in certain Ceretaceoua strata of the
States which border the Cnlf of .Mexico; rxtendinj;- westward into the
Uepnblic of Mexico. It was tirst pnblislied by KVemer in Kreidebildniifr
V)ii Texas, pajre 71, IMate IX, Fifjs. 2, a, h. A.s before remarked, it has
by some authors been re^jardcd as not specitically ditl'erent Irom E. cos-
tatii Say. Tlie two forms are certainly closely similar, but their surface
characters are njjparently constant in their did'erence, even when they
are found associated in the same stratum. The lower valve of this
species is very massive in old examples, sometimes reaching: nearly two
inches in thickness of .solid shell substance.

Exogyra parasitica Gabb.

(Pl.itoI.V, Fif,'s. ;!,4.)

Mr. Gabb jiublished this form in Paleontology of California, Vol, I,
l)a^'e 2()5, Plates 2(! and M. It is interesting^ because of the very slifjht
rei)resentatioii that E.vo()\jra has in the Cretaceous strata of the Pucilic
coast.

Exogj/ra tcxana IJa'-iner.

(IM.iio 1,1, 1'igH. i,'.',;i,.i,,'-).)

Professor Hcenier published this specie."? in Kreidebildung von Texas,
pajre ()!», Plate X, Figs. \,a, b, c, d, c. It is not unfrequcntl.v found in cer-
tain Cretaceous strata in Texas and the adjacent parts of Mexico. It
has been by various authors referred to £. ylicata Luiuurck, aud E.
Matherouiana d'Orbigny.

*"'T«1 CRKTACEOUS, 307

I'jcogyra icalkeri White.

(I'lutr LIV, TiK^. I, 'J.)

This JH a hunt', iioimiuchnimI form, which coiiioh from tht( Crctaeooua
Ktratii of Texas. It was ])uiilisli*Ml in ilin Annual lU'port of liio Unitotl
Htatos (ii'ohj;,Mcal Hurvcy of tht< Tcrritorit-s for 1877, i)aj,'o li7S, I'hito I,
FiKs. 1, a, h.

I'hogi/ra winchclU Wliite.

(IMiiti! I,V, I'ijrs. n,7; riato I,VI, ri),'H. 1,-J.)

Th(^ form whiiiii is most nearly related to this speeit^s is tlic hi hatio-
toitlrii of Sowerliy, hut it is more elou^j.ite than that shell, an*l the front
Hithi is more abruptly elevated. It is probable that this Anieriean form
mit;ht be with jiiopriety ree,o^iii/ed as a variety of the ICuropean L\
haliotoiilni, but I prefer at present to refjard it as distinet. I have
re(;oi;ni/ed iho last-named speeies anions souu! Cretaceous fossils from
Hrazil, and they seem to bo sulUeienlly distinet from E. winchvlli. It is
only in the Cretaceous strata of the (lulf States that IJ. winclirlli is yet
known. It was iiublished in the l'ro(!eedings of the United States
National Museum, Vol. II, jjajje li'Jt, i'lates II and III; and also in the
Annual IJeport of the United States CJeoloj,'ical Survey of the Territories
for 1878, page VJ, Plate XIII, Fijjs. J, a, b,c,d. '

LARAMIE GROUP.

The preat brackish water formation of Western North America, which
is known as the Laramie Group, has already been referred to. In this
great formation no true marine fossil remains have been found, but
oy.ster .shells are not unfrequontly found in its strata, and in some places
they ar(>, abundant. Among these no less than live species have been
proposed by difl'crent authors, but later collections show such gradations
of form that I have not been able to recognize more than two species
among them, and it is pro'jable that there is reiilly only one species in
the whole formation.

These oyster remains of the Laramie Group not only belong to the
typical genus Oxtrca, but the most abundant of the two recognized
species is very closely \i\n'. the living Oxlrca vinjinica. This species is
quite constant in its lyjiical form, even at points more than a thousand
miles distant from, each other, and the extent of its geographical ilistri-
bution seems to have been quite e(pial to that of the living O. vinjinioa.

Ostrea glabra Jleek & Ilayden.

(Plates LVIII, MX, LX, LXI.)

This widely distributed sp cies was first published under the above
name iu the Proceedings of the Academy of Natural Sciences of Phil-

308

K0881L OSTRKIDiK OK NORTH AMKRICA.

iHli'lpliia, for 1857, pnKO 13(1. The typo Hiu'cinicnH were obtained from
Mm Upper MisHoiirl Kivcr n-Kioii j iiiid the BinootliiiCHM wliifli HU|;{;c'Htcil
tlu'ir Np«'cill«! iiaiiic was not natural, but duo to attrition or corro8ion.
FiKiin-M of out' of Ihcso t.vpo NpocinicnN nro tiwvw on plato LVIII. lu
Jlic Animal Itcportof llio UniH-d HtatoH (!coloj;lcal Hurvry of the Terri-
tories, lor \H-,2, \>i\m> TtOH, Mr. Meeli deMcrihed a form I'rom Hoiitiiern
W.vominy; niidcr the name of Onlnn iri/ominiimiH, ll;,MireH of wliicli are
jjiven on I'lates liX and LXI. In tin- .samewerieHof reports, the volume
for IST.'t, pii^e 177, he deserii)ed anotlier form from tlie same loeality
under Ihe name of (K (iiriinliliH. Fij;. o, ou Plate MX, Is drawn fnmi
his type speelmon.

In I'dwell's Keporf on the (ieoIo;,'y of the rnlta Mountains, pa^e lili,
I ile.Mrilied another form from Honthern U'yomin;,' under Ihe mime of
(). hiHiriiriK. Fi^'ures of tlie type speelmen are jjiveii m Plate lAX,
Now, all iheM- formM, as before mentioned, I regard as belonniiiK toono
an<l the same species.

Ostrca utihtrigonalis Evans & Slnimard.

(I'lat.i LXr, I'iKH. •«, t,, a, 7.)

This small form occurs In the Laramie strata of tbo Ui)per Missouri
Hi ver region. It is not imjMobalile that this also is a variety of 0. (jluhra,
but the somewhat numennis specimens that have hitherto been discov-
ered are very uniform in size and shape, the size beinj? consideraldy
snmller than tJie averuRO of 0. (jiahni. It was oriffinally published with-
out llf,'iires; but it was identilled by Meek and illustrated by him in
Vol. IX of the United States (leologlcal Survey of the Territories, Plate
40, Kljfs. 1, a, b, c, d.

tan

A IM' K N I) I X I .

NORTH AMKRICAN TERTIARY OSTRKlDil.

By Pro-'. Anoki.o IIioilprin.

fliMiim Ohtrka LiiiniuuH.

KOCKNK.

Ontrea alabamcmh Iami.

(I'luf« I,X1V, I'lgH. 8, 3, 4.)

Orijliiiiilly i)iil)li8lK-(l from Alubaniii in Leu's Coiiti ibutious to Geoloffv
I)a««9I, Pluto III, l-'i((. 71.

8VN.— (>. lingiin-ciitiin l,m. Il>., puno 98,
O. pincnnii t.cii. II)., |m){« 1)8,
*f>. Ktmllunnta Lcii. II),, pajfo <N),

Ogtren viiroJincnHiH Conriul.

From aouth Carolina. PiihliHliod in Conrad's FoN,si! Shells of tlio
Tertiary Formation, lirst edition, page 27, Plate 14, Fig, 1.

Oatrea comprenHiroHtra Say.

(Plato I.XV, FI^H. 1,8.)

PnbliNlied Irom Maryland, in the Journal of tlio Pliiladelphia Academy
of ^'atural H(;ieiices, IV', jiago \'M.

HYS.~(). b<lhraihi„ Cmua.l; I'nx' liiinN .,f ihc N.ilional IiiHlit ,(,., |)„B<a78.

It ai)i)ears to me very doubtful whether the chaiacter of the beaks
pointed out by Say (.Journal of the Academy of Natural Sci.^nees, IV
l)ago i;j;!) to distinguish this species from the 0. hcUonwina Lamarck, is
a constant one or not, and I have therefore some hesitation in rcco"ii'i/.
ing it as a distinct si)ecies. The beaks of O. cowprc.ssirnstni ccrtainrv do
appear nuuv compicssed than they arc shown to be in the miijorily of
tigures representing liu'Huropeano.vster; but at least sonu- of the speci-
mens in the collection of the I'hiladelphJa Academy of Natural Sciences
of 0. hdloracina (var. nliilln,,) from the LoiKb.n Clay of Hognoi, have
the beak undistinguislmbic from those of the American sj)ecies.

The want of specimens with which to make the proper comparisons
and the dillieulties that attach to the dclinition of the spccilic charac-

• This Inst form !b very (listiiict from tho 0, aella-formis of Conrad,VLka»i^otic«l ou
a following l)agc.

309

;u()

rOSSIL OSTREID^ OF NORTH AMERICA.

tcrs ol tin' Ostrt'idic prevent me from c.\i)ressing a definite opinion sic: to
tlic iclationsliip oC the two speeies. Tlie fijinres of 0. Iivllorachia na
iihvM li.v Searles Wood in Ids AhniojiTiipii «l' tlie lOoeene Mollnscii (Tide-
ontolofiical Soriety's Keiuirts for 18(11, Plate VIII, Fi{;s. ;?, a, b, r),
aeeonl almost i)erfectl,v with the Ameiiciin oyster. The oyster found
by Lyell in the "drove " about 17 nules nortli of Cliarleston, S. C, and
which api)eared to him '•undistinjiuishable from (). bclloravina " (Jour-
nal of the (ieoloyieal Soeiety of London, l,j)at;e 4;);>) is i)robably the 0.
carol inoinis Conrad, a form very closely allietl to 0. c»mj»r.s').//-()sO'((.

Ontrot cretacvit Morton.

This sjiecie-s, de.scribed by IMorton in the Synopsis of the Orjranie lUv
mains of the Cretaeeons (Ironp, pa^e 52, Plate XIX, Fifj. ,'{, is fonnd in
Sonth Carolina and Alabama (?). It is {jiven as lOoceneon the anthority
of (iabb (Proceedii-^'s of the Phdadelphia Academy of Sciences for 1801,
l)ase;{2S; " IMolhi.sca of the Cretaceou.s Formation," page loi!) and is
not inclmled in Conrad's Check List.

Ostrea divurifuta Lea.

(Plato I.XIV, Fig. 1.)

This was published by Lea amonjihis collections from Alabama in his

Contribution to Geology, jjage !»1, Plate III, Fig. 70.

SVN.— O. fiubiUula\ Laimiiik.

Tn the Proceedings of the National Institute (1841-'C, ])age l!).'i), as well
as siibsecinently (American Journal of Conchology, 1, jiage 15), Conrad
nniiesi;,itingly refers this sjiecies to his O. ncllwformis — a view which
appears to me to be decidedly erroneous. Although the two species
<'losely resemble each other in the young stage, they may, nevertheless,
on close ins])ection, be readily distinguished from each other. The dis-
tinguishing characters between O. diroricata and O. /(ilcifoniiis Conrad
(American Journal of Conchology, i, jiage 140) are not so easily made
oi't. and I must confess my inability thus far to discover what they are.
The 0. (liraricata certainly agrees very closely with the ligures and de-
scrii)tion of Lamarck's O. .//((/><■//(//«, to which species it is in fact uidiesi-
tatiiigly referre<l by Nyst (t'otju. et Poly]). Foss., ])age ;!'_'.'!) and (iicbel
(Kci'.ertorinm to (ioldliiss' Petrefacta (iermaniu', KS(1(>, p. 41). The last
is a very variable and one of the most widely dispersed of fossil oysters,
its range extending from Alabama (l)eshayes; and iTOrbigny, Prodrome
de Paleontologie, 11, page .'!!)4) to (hitch, in India, and Cairo, in I'lgypt
(I)esiiayes, Aniiii. sans Verlebr. liassin de Paris, 11, jyage 121.)

OatftM crrrsit ^Meiiville sj).

(I'lalr LXIV, Fi-s. 5, ti, 7, 8.>

A fossil of the French Eocene (l)eshayes, Anim. sans VertM)r. I>as-
sin de Paris, II, i)i'ge !)lt, Plate 84, Figs. 5-8), identified in the I'joceuo
of Maryland and ^!ississii)i)i.

Sy.\. — Griiphostrca vrrraa Coiirail. Siiiillisotiian Chock List.

IIEII.IMIIN I

TKRTIARY.

311

#><

Ostri'd /iilvi/dniiis Coiinid. '

AiiRMicaii .lomiiiil ol' Coiicliolopy, I, pago, 110. From Mississippi.

^''YS.—O. iliriiriciihit I. Oil. Sii|irii.

(htrcd murtoiiii ('r.ihh.

I'loiii Aiiihiiiiia and Soiitli Carolina, rrocot'din^is of flic Academy
of Natuial Scicnci's of IMiiladcIpiiia i'or 1801, jjajio 3-!).

.Syx.- I). iHiinlii (iiiir.s) Mcirlon. Symipsis Or;;;iiiic Ufiiiiiins, piiiji' ."il.

O.strra stihv/onuis Conrad.

(Plilo I.XII, Fi^M. I,--'; ri:it(> I,Xll[,l"in. I.)

I'roiii tlio Eoi'ono of Alabama, South Carolina, and Virfjinia. Piib-
lislicd by Conrad in bis I'^ossil Slu'lls of the Tcrliary Formation, Hist
edition, pa;.o '21.

Syn. — (>. nii/inno Conrad; siiiiu' wdiU sini] piifjc.

O.strcu tliirnw Gabb.

(riatc I.XIII, Tins. .1, .s, i;.)
Tlii.s form was ]>tdilisli('d by Gabb as a ('retaceous si)i'(',';s in tlio Pro-
cecdinfjs of the I'liila(k'lpliia Academy of Sciences for 1801, i)aj;«! MO;
but it is now known fliat the strata I'rom which it comesareof Foccneafjro.
G;ibb referred it to the <;enus (Iii/i'Ikvi:, but, althoufih it api)roaclies 0.
rcxivularis in Ibrm, I am disposed to place it under true Ostrcn.

Onlrrii tridonalis Conrad.

I'roceedins's of the I'hiladelpiiia Academy of Natural Si-iences, VIT,
pajio L'iV,). From ^Mississippi.

f Ostrcd tuomnji Conrad.

This nanu' is jjiven by ('onrad, Xo. 0!).') of the Smith.sonian Check
List, as citminj;' I'roin .Mississippi. I have seen no specinu'ns of this
species, nor have 1 been able to discover where it i.s descrihed.

Ostvca (]rnrglnnn Com ad.

Ot.KiOCI'.NK.

Ostrca <]rnrgiann Coniad.

Conrad imblishcd this speciis in the Journal of the I'iiiladelpliia
.Vcadeiny of Natural Sciences, \'ll, ]>. l.")0. Il is ic|>orl('d as coiium^;
from Georgia, .South Carolina, Mississippi, and Lower California (?1.
There is a larjic oyster in I he ('(illc<-t ion of I he .\cademy from Lower Cal-

There is a larjic oyster in the c(illc<-i

ilbrnia, marked ().<]t'or(iiuiiii ; it cerlainly L;reatly resembles that species,
but its characters are to soni(M'.\teiit obliterated, which prcviMits abso-
'■"' :i ■■•:': ■.:-,_ [ slioidd liot lic surprised if, on comparison with

lute idcntilicalioi

ute idcntilicaliou. 1 shoidd not be surprised if, on comparison wi
l<!uroi)ean spccinu'Us, the <>. (lairiiiaiKi will be found to be only a varie
if 0. frtinsissiinit I inarcl: (Miocene of a vciy laifje portion of I'Inropt

variety
pe)

312

FOSSIL OSTKEID^ OF NORTH AMERICA.

The reseniblnDce of the figures of that species is very great; and if
the American oyster does not assume quite the ponderous proportions
of its European cousin, the circumstance may be due to local causes,
such as crowding. Conrad states that this species reaches a length of
22 inches.

Ostrea vicksburgensis Conrad :

(Plato LXIII, Figs. 2, 3 )
This species is from the well-known locality of Vicksburg, Miss. It
was published in the Journal of the Philadelphia Aciulemy of Natural
Sciences, Vol. I (u. s.), page 126.

MIOCENE.
Ostrea attcoodi Gabb.

(Plato LXVIII. Figs. 4, 5.)
This species is said to be either Miocene or Pliocene. It was pub-
li.shed in the Paleontology of Calil'ornia, II, pages 33, 34 ; Plato X Figs.
58, 58n; and Plate XI, Fig. 58b.

Ostrea borealis Lamarck.

This fossil form is id»>ntifii'd with a recent species.* It is published
in Laman-k's Aniiiiaux sans Vertebres, second edition VII, page L'20.

There are in the Academy's collections lour specimens of an oyster
niiirked "St. Charles, .Maryland, Cope" which answer perfectly to
IjaiiiarcU's sjiecies. It is probably Miocene.

Ostrea cvii.lracta Conrad.

(Plato LXIX, Figs. 1, •_>.)
This species is rejiortcd by Conrad as coming from Oyster Point,
Mexico, and as probably Pliocene. It is published in the Keport of the
United States and Mexican Boundary Survey, I, page IGO, having been
previously piiblislied in the Proceedings of the Philadelphia Academy
of Natural Sciences, V',!, page 2«9.

Ostrea dispdrilis Conrad.

(Pliitf LXVI, Fig.s. 1, 2.)

From Vir;;inia and South Carolina. Conrad's publication of the
species is in liis Fo.ssils of the Medial Tertiary rorniation, i)ago i^JJ,
Plate lid.

Syn. — 0. rai-eii,liit»a Tiuiiiicy & Holmes, in I'liocoiU' Fiissil.s, page 21.

The dift'erences wliich were pointed out by Tuomey & Holmes as
separating 0. roveneliana in.m 0. disparilis cannot be said to exist.

* See Plate LXXX lor receut specimens.

•4

imLPuni.]

TERTIARY.

Oatrea panzana Conrad.

Conrad publisLed this form as coming from California in the Pacific
Eailroad Reports, VII, p. 193. He regarded it as possibly the mature
shell of 0. subjecta. I hare seen no specimens of this species; nor is
ii determinable from Conrad's figures. Gabb was unable to recognize
it among the collections of the California Survey.

Oatrea percrasm Conrad.

(Plate LXVII, Fig. 3.)
This Miocene form has hitherto been recognized only in New Jersey.
Conrad published it in his Fossils of the Medial Tertiary Formation,
page 50, Plate 25, Fig. 1.

Oslrea sculpturata Conrad.

(Plato LXX, Fig. 2.)
From Virginia. Published in Fossils of the Medial Tertiary Forma-
tion, page 50, Plate XXV, Fig. 3.

Syn.— 0. rir(iitiiana vnr. Conrad (non Gmeliii): Fossils of the Tertiary Forma-
tions, lirst edition, p. 28.

Ostrca subfukata Conrad.

(Plate LXVIII, Figs. 1, 2, :i.)
From Virgiiiiii. Publisiied by Conrad in his Fossils of the Medial
Tertiary F rniation, page 50, Plate XXV, Fig. 2.

Ostrea suhjccta Conrad.

Reported as coming Irom California, and published in the Pacific
Railroad Reports, VI 1, i)age 193. I have seen no specimens of this
species, nor is it determinable from Conrad's figure. Gabb was un.
able to recognize the form among any of the collections of the California
Survey.

Oaiera fayhirinDa Gabb.

(I'liilo LXVII, Fig. 1, 2.)
From California. Published in Paleontology of California, II, p. 34,
Plate 12, Figs. ()0, C0((.

Ostrc'i titan Conrad.

Coiinwl i)ublisiied this large oy,ster in the Proceedings of the Pliila-
delphia Academy of Natural Sciences, VI, i)age 199; the Journal of
the .same (n. s.), IV. i)age 300, ami the Pacific Railroad l{ei)orts, VI,
page 72.

Tills is to my knowledge tiie most ponderous o,\ster found in tlu>
United States. In (•ertain of its forms it so closely resembles the 0.
f/ingensis of Sehlotheim as to be but barely separable from tiie common
European species. Like it, it also affects the long, the curved, and the
8e()oi)e(l forms, the spare between the va!ves in the last case being very

314

FOSSIL OSTRF.IDiE OK NOinil AMF.RiCA.

ciipacions. All tiiicesnf radiarc idications, if it oviT iiossesscd any siuiii
ornaiiit'iitatioii, liavo (lisappcarcd in tiu' spcciiiifiis lict'oie inc. The
loiifi fonus may Ik; ivadily (listinjjiiislicd Crom tiic O. crdssixulnia I,a-
niarck by tlio comparative siiortiicss of tlic nmbonal rcyioii.

Osirea rchfinua ('oiirad.

^I'hilii 1,.\X, Ti-. 1.)

Tiiis species was colii-ctcd in Ai'izona by the United States and Mexi
<Mn J>oiindary (Jomniission, aTid ])ublislied in Vol. I, Part II, pa^e Hit).
It is stated to be probably Miocene.

(htrcd virghiica Gmelin ( = 0. vmi'minnn I.amarck).

Syx. — 0. mauricennin Gabb ; .iDiinial of I ho riiiladelphiii Acadi iiiy of Natural
.Soicnccs, IV (n. h.), \>'d'^c liTli.

The O. maiiricensis does not appear to dill'er materially, if it differs at
all, from the lon,sj fcrins of 0. virginicn. This species has been found
fossil in New Jersey, JIaryland, Virjjinia, North Carolina, and South
Carolina.

A fossil form of the I'aluns of Touraiiie. and in the vicinity of Bor-
deaux, is rccofinized as identical with the common living oyh er of our
Atlantic coast — 0. virgimca {"Sldm. 8oc. Gcol. dc France, II).

PLIOCENE.

Ostrca atwoodi Gabb.

This species has already been noticed under the head of Miocene.
Gabb was undecided wiiether to refer it to .Miocene or IMioceuo age.

Chtrea botirr/eoisil licmond.

(Plate I,XXI, I'if^. 1.)
rul)lished in the l'r<iceedin^s of the Calilbrnia Acadeaiy of Sciences,
ISti.i, paj;e 1.5, and by Gabb in Paleont()I(),iiy of Calilornia, II, page 33.
It is lei'erred to the Pliocene strata of California.

Ontrcd ln'cniKunii Conrad.

This is also a ri'imted Calilornia species. It was ])ul)lished in the Pro-
ceedings of the Philadelphia A("adeniy of Sciences t'oi' ISo,"), ])age '_'(i7;
and in the Pacilic Railroad Iteixirts, \', page .'{L'ti.

Tins s|)e(!ies was originally described as ]>robably .Miocene (as prob
ably from the .same deposit which contained (>. vcxiii'rtina),i\U{\ is given
as sncli in MeeU's Miocene I .st ; but in the appended "Notes and Vj\-
lilanations"' (page I'd) it is .'^tated that "(.'onrad now thinks his Oxlvrit
li ccr 111(1 II iii ])robably a Cri'taceous s])ecics." Carrizo (Jreeli, Colorado
Desert, when; it was found, is Plioceiu', according to Gabb; and the
O.harmaiini is accordingly given as a Pliocene species in Paleontology
of California, 1 1, j). 107.

IIKII.l'lllN.I

TEUTIARY.— POST-TKRTIARY.

315

Oistrea vcspertina Conriul.

(I'latuLXXI, I'iss. y, ;i, 1.)

This form was published in the Jounial of tlic PliiliKU'lpliiii Acailciny
of Natural Scicnucs, II (ii. s.), page 300; United States and Mexican
Boundary Survey, I, page 100; and the Pacific llailroad Keports, V,
l)age M.-,.

It is closely related to both O. suhftikata and 0. scalptufnta, and Ih
])ossil)ly only a variety of one or the other of these species. It va,s
originally described as Miocene, but the locality where it was obtained
by Conrad, Oarrizo Greek, Colorado IJesert, is considered Pliocene by
Gabb.

POST-PLIOCENE.

Ostna conckaphila Carpenter.

Tliis name is given as that of a California shell in the Catalogue of
Mazatlan Shells in the British Museum (1857), page IGl ; but not
figured.

Theie are nine specimens of an oyster in the coUectioM of the Phila-
delphia Academy, marked " 0. conchaphila, Cpr.," from the post-Plio-
cene of San Diego and False Bay; but whose determination the same
may be I am unable to state. The 0. concliaphila, as far as I know, is
not stated to be fossil bj' any i)aleoutologist. Some of the above speci-
mens are undistinguishable from lecent speciuh'us marked O. lurida
Ci)i'., also in the Academy collection, wlijcli is stated to be fossil by
Newberry and Gabb. It therefore ai)pt'ars to me that the specimens
marked 0. concliaphila are more likely to be 0. lurida, although their
characters do not exactly agree with Cari)enter's description of the
lattei- s);ecies.

Ontreafiindata (Say?) F. S. IJolmes.

Post-Pliocene Fossils of South Carolina, ]). 11. I have seeji no speci-
mens of this si)ecies.

Out ten (jallust Valent iennes.

Figured without description, Voyage de la \'(muis ; Atlas de Zocilogie,
Plate 21. California. A lecent .species.

SYN'. — <). cfmiHiiifit (.ialMi; riilfiiiitiildgy (iT Ciilirurnia, II, jiago '\'i. Ct'rros
ImIuikI.s.

As stated by Gabb, Paleontology of California, II, |)age 100, O. cer-
roscnsis is in all probability iilenlical with 0. gallus, which, as figured,
is about twice the .size of the California tbssil. A fossil from the late
Tertiary of Peru, received from Professor Paimondi, which is consid-
ered by Gabb as the e(iuivaleiit of his (). crrroaensis, is about the size
of the living 8i)ecies, and undittinguishable from it.

mmm

316

FOSSIL OSTREID^ OF NORTH AMERICA.

Ostrea lurida Carpenter.

(Plate LXXII, Figs. 2, 3.)
This living species is mentioned as fossil in tbo Pliocene of California
in Mollusks of Western North America (Smithsonian Miscellaneous
Collections, 252), page 305. It is not figured in that work.

Syn.— O. ediilh Cooper (uou Lin.) fide Curiieiiter, loc. ci<., page 85, — Gabli,
Paleontology of Ciiliforuia, II, i)ago 106.

From Benicia. Fossil at San Pablo, according to Dr. Newberry (teste
Carpenter, loc. cit., page 300).

Ostrea veatchii Gabb.

(Plate LXXII, Kig. 1.)
This is another California species published by Gabb in Paleontology
of California, II, pages 34, 60.

.J.

...

APPENDIX II.

A SKETCH OF THE LIFE-HISTORY OF THE OYSTER.
By John A. Eydeb.

TIic oyster always preseuts a definite right and left side; a dorsal or
upper, and a ventral or lower part of tbe body, and an anterior or head
end to which the hinder extremity is opposed. Thus it will be seen
that it resembles greatly many eomnion animals, not only in the respects
already noted, but also in that the right and left halves of the soft ])art8
are, with the excei)tion of the alimentary canal, repetitions of each other,
so that, as in man and the higher animals, there is a|)parent in the oys-
ter that likeness of oi)i)osite sides of the body which has been termed
bilateral symmetry. While this symmetry of the soft parts is so evi-
dent, it is less palpable when we compare together the two valves or
shells which inclose and protect tlie animal. In the natural beds the
left valve is usually undermost or inclined to be so, but in the (srowded
banks the shells, as growth proceeds, tend to assume a vertical i)osition.
The left valve is also more concave or hollowed out internally than the
right one, which is often very nearly flat. In the European oyster
tOntrea editlis) both valves are much flatter than in the American and
Portuguese (O.virginka and 0. angulata); in the former the muscular
impressions are also very nearly pyriform aud colorless, while in the
two latter they are usually more nearly kidney-shaped and deep purple
in color. The average size of the American and Portuguese is al o much
greater than that of the common European species, and both the former
grow much more rapidly than the latter.

Fig. 1, Plate LXXIII, represents an American oyjter which has had the
right valve and the most of the mantle of the right side removed, in order
to show the soft parts in position as they lie on the left one. The head end
of the animal lies close against the hinge h, or the point where the two
valves are firmly joined to each other by a dark-brown, crescent-shaped,
elastic body, I, known as the ligament. This ligament, while it serves
to attach, also tends, because of its elastic properties, to separate the
valves from each other at their broader, free extremities. In life, this
separation of the valves at their wider free borders admits of the ready
passage of water inwards to the gills <ji, and of food to the mouth jm, while
it also allows the water which has passed through the gills to escape by
way of the wide cloacal space cl, carrying with it in its current the faeces
from the vent or anus v. The tendency to separate the valves, inherent
in the ligament, is balanced by the adductor muscle M, which upon the

317

?1«

rOSSIl, OSTRKID^, OH" NORTH AMIRICA.

Hlijjlitcst iiitiiiintioii of external diiiiffcr forcibly contracts, closing Uih
free edges of the valves tiglitly. Tiic d;!:k purple scars near tlie centers
of hotli valves, and vulgarly supimsed to inilicate the position of the
lieart, are simply the areas covered by tlie attaclinient of tliis adductor
muscle, wliitili is comimsed of a vast number (rf extremely fine uinscular
fibers, wliicli collectively jiass straight across llio space between the
inside of the valves, being firmly fixed at either end to the latter.

The nuiscle M when closely examined is found to be composed of
bundles of fibers composed of still more slender fibrils, which art! the
contractile elements of this strnc^turo in the oyster. Th se fibrils are
analogous to somewhat similar minute elements in our own muscles, to
which niKscular contractions arc primarily due when evoked by some
stimulus, such as that communicated by a very fino nerve fiber ending
on the surface of the innscular elements. Two kinds of fibers are also
found in the adductor; the first of wliich is the whitish, glistening variety
found in the hinder crescentshai)ed i)art of the muscle, and the second
a i)aler, less lustrous, and grayish kind found in the darker and more
anterior portion, as has been indicated in Fig. 1, by a dilierent shading
of the two ninsc(dar areas.

Another small muscle is found on either side of the body of the soft
parts, an inch or a little more in front of the great a<!ductor. Its i»osi
tion and sizearo indicated in Fig. 1, at p', where it passes out through the
mantle a little way behind and above thei)ali)S2), to be inserted into or
attached to the inside of the valves a little distance behind the hinge h.
This small muscle does not i)ass across the space between the valves
like the great adductor, but its inner end is soon lost in the lower an-
terior part of the body mass ; it is in fact a paired structure, the one on
the right side of the body being a rei)etition of that on the left. In the
American oyster its insertion on the inside of the valves is sometimes
marked by a small puri)lish scar about one eighth of an inch in diameter.
This muscle has been identified with the |)edal muscle of other moUusks
by Dr. W. H, Dall, who was, I believe, the first to call attention to its
existence.

As the oyster grows the insertions of both the great adductor and the
pedal muscles enlarge and are extended jirogressivcly backwards on the
inside of both valves and away from the hinge, as may be learned ujwn
examining the muscular insertions on the valves of an oyster recently
ojjened. There are no other i)oiiit8 of attachment between the soft
l)arts and the valves, excei)t the opposite extremities of the great ad-
ductor and the small pedal muscles of either side. The soft parts are
therefore in life adherent to the shell at four points.

The foregoing i)ariigra|>hs fairly describe the mechanism of the shell
and the manner of its relation to the soft i)arts, and also partially indi-
cate the reciprocal i)hysiological relationshij) subsisting between both.

The structure of the shell is laminar, or, in other words, it is composed
of very numerous and thin parallel layers of calcic carbonate ^chalk),

iiruKU.)

MKK-lIIiyrOKV 01' THE oySTKR.

8I>

(U'posikMl in succession one nixin tiie top of the oilier by tlie niantlo in
an orpiuii: liorny niutrix Known as concliiolino. Wiien tiie snrfaee of
these layers is < xainined nniler (he niicroscope tlie eaieic carbonate la
found to l)earriin;r(Ml in miiinle jiolynonal liloelisor laisnis. The horny
matrix of (lie siiell, as well as tlie caleareons matter, is deposited l»y
the mantle, and is jjrimarily derived from the food and earthy matters
swallowed by the animal.

The layers of ealean ons matter, deposited as they are internally, as
growth proceeds, project in succession i)ast each other at. the free ed;,'e8
of the valves and i-xtcrnal surfaces of the shell, so that the sncc'cssivo
deposits may b(!<listinj;uished. Itis also evident that deposition occurs
to some extent iteriodically, which {iives rise to theroujih imbricated
ai)pearauee of the ed^'es of the layers which terminate on the outside
of the shell. IMoreover, the rate of deposition vaiiea at diH'erent points
around the margin of the shell, so that f;rowlh of the shell may take
l>lace more rapidly at one part of the margin of the valves than at
another.

Cavities tilled with fluid are frequently found in the ci'lcareous valves
of the oyster. They are usually shallow, .aid of no very great extent,
and aiise in consetjuence of the numner in wlii(!h the calcareous nuitter
is dejiosited by the mantle, the new layers not being laid down in im-
mediate contact with the preceding ones, where the cavities are formed.
Such cavities are al.so sometimes formed in consequence of the encroach-
ment of mud between the valves, as shown at x,x,xm Fig. 1. In such
caso-s the animal has sunken too deejily into the ooze, wliicli then found
its way into the shell while the aninnd had its valves parted when feed-
ing. The nuid wliicli in such instances has insinuated itself between the
mantle and shell is immediately covered by thin deposits of calcareous
nmtter secreted by the border of the nuintle. Inclosed in this way by
calcareous deposits the included mud is rendereil harudess to the soft
and delicate structures of the inhabitant.

In Fig. 1, the back or dor.sal side of the aninud, it nmy be observed,
extends anterioi ly from n to y; the ventral or lower side n'aehea from e
to y. The right and left sides of the animal are covered, in life, bv an
organ called the mantle, mt. (In the figure the mantle of the right side
has been entirely removed, excejjt a small triangular patch vit', which is
closely adherent to the front part of the body mass.) This organ is
thin; it is in fact a Hat membrane, which is not attached to the shell
anywhere excei)t around the jioints where the ends of the adductor
muscle M and the pedal muscle p' are allixed to the internal surfaces of
the valves of either side. This organ, as may be seen from the figure,
incloses, like the covers or lids of a book, the other solt i)arts, viz, thegills,
body, and palps, which are in truth susi)ended between the two great right
and left leaves of the nnintle. The margins of the nianllelobes of either
side are joined together tor only a short distance at the head end of the
auimal, or from n to z, forming a sort of hood over the mouth and great

I'OSSIL OSTRKIDit OF NOHTH AMKRICA.

fleshy lips or palpH p, iiml closed iibove tlie latlcr. roHteriorly, at y,
wlit'icthc (,'ills terniinate, tlio tiiaiitlo leaves of opposite mdcH arejoiiied
together by a narrow transverse nieinbraiie, wlii(!li extends downwards
and lorwards Corniiiij,' the floor of the cloaca cl and the space between
the ventral process of the body nniss/ and the gills. This narrow mem-
brane IS perlbrafed by t'onr parallel rows of jtores, bp, which lead down
into the divided internal cavities ot the gills.

I he IVee margins of the mantle are fringed by two rows of short, pur-
pli.-li, extensible, and highly seiisiiive tentacles, which are supplied with

nerves from the great ner\iiusgaugli(iry(f/,out he lowcriiideoftheadductor
M. The tentacles are i)rotrudc(l sli;;|itly beycuid the edges of the valves
when the animal is feeding, iuit they are (piickly willidrawu upon any
intinialion of danger by ihe contraction of the slender, brandling, mus-
cidar buiulles which radiate (Uitward in all directi(Uis through the man-
tle leaves of either side from around both of the insertions of the great

adductor .lA The radiating muscles of tl antle cross the marginal

ninN<nlar (Hicrs of the mantle border at rigiit angles. They may col-
lectively be called the pallial muscles.

The oyster is classed by naturalists amongst what are called lamelli
b'anchiate mollusks, or those which tend to have the gills w branchiic
developed as great flat parallel jdates, or lamella-, whence the name.
In the oyster there are four gills, alongside of each other, which extend
from behind the pali»a jj to the in.int y. They are not really simple Hat
plates, however, as we learn upon examining them clo.sely. They are
really much more coinide.x organs than nnght at Hrst be supposed.
Each gill is in fact composed of two rows of conjoined fleshy i»arallel
filaments fused together at their edges and lower ends and joined above
to the pertbrated fleshy membrane already alluded to. They are there-
fore in reality long and narrow hollow satiks. Their cavities are, how-
ever, subdivided by fleshy, transverse partitions at narrow intervals.
The appeaiance of the gills, with their internal cavities, when cut across,
is shown at ()', in Fig. ;i, which reiiresents a cross-section through the
mantle, gills, and body of an oyster, enlaiged about two diameters.

If we inspect the outer surfaces of the gills we will find that flno
parallel ridges or ribs, with intervening furrows, exteinl vertically up
and down, which give rise to a striated ai)pearance on the surface of
the branchiaj to the naked eye. Under the microscope these ridges in
turn are found to be nnideup of still liner parallel ridges or ribs. A still
more searching examimition reveals the fact that there are rows of very
fine pores between these ribs, which open from the outside into the cav-
ity in the gill. On this account we are finally forced to regard the gills
as sieve-like structures, a conception of them which is further justified
by the fact that the gills have i.;i exceedingly delicate internal skeleton
ai)parently composed of a horny substauce, the meshes of which are
square or in the form of oblong squares, and around which the soft parts
of the gills are built, and by which they are sujiported. It will be gath-

MTiiiiri ]

LIPE-niBTORV OP THE 0V8TKR.

321

orcd from flio prt'ci'diiiir nccoimt that tlioso orpins are quite dittV-ront
la Htriictiirc from those of llshoH, in which we (Irxl two rowH of liraiiehial
]>roccHHes, arraiiKtMl liiui tlie teefli of u comb, Niipiiorted at the outer
marfiin of about live bony aniiie.s, with j,'il! elefts or slits between tlio
latter, wiii(!li open onhvards Ironi tlie fore part of the sidesof tlie tliroat.
In the o.vster tlie f,nlls liave no eorniection witli tlio throat, and Iiavo,
moreover, as aheady staled, tlie form of elongated saeks, with porous
walls, with a row of large i)ores opening above info the cloaea cI,uh
Bhown in Tig. 1. Tlie lateral pores between the ribs on the gills, and
oi)ening into the cavity of the latter, and these cavities in turn opening
by way of the rows of large ]n>ivs,hp, into the cloaea cl, iiermit tho
water necessary for respiration to readily i)ass through the gills, as indi-
cated l)y the course of th»! arrows in Fig. 1.

The way in which the water is forced through them is, however,
quite dilferent from that observed in fishes, in which the water is
])nmi»ed through the gills by tlie action of the mouth and gill covers.
In tho oyster, on the other hand, fresh supplies of water are swept
through the pores and internal cavities of the gills in an entirely dilfer-
ent way, viz, by means of very numerous minute and slender processes
with which these organs are covered. These proceiises, or cilia, as they
are properly called, vibrato or swing to and fro many times per second,
and more forcibly in one direction than in another, so that they set
up a current of water in tho direction of their most forcible vibration.
This, in brief, is tho means by which tho water ia swept through tho
gills of tho oyster in a continuous stream, ministering to respiration or
oxygenation of tho blood of tho animal in its passage through tho
branchial organs.

Tho blood of tho oyster is normally colorless, and much more watery
than in higher animals with red blood, in which tho blood-cells or cor-
puscles are also discoidal or oval and flattened, while in the oyster they
are nearly globular, as usually seen floating in tho serum. They meas-
ure about one three-thousandth of an inch in diameter, but vary some-
what in size. They are in reality very small lumps of protoplasmic
matter, provided with a nucleus embedded in their substance in an
eccentric position. They undergo great changes of form when taken
from tho animal alive, and may live for four hours under the micro-
scope, during which time they may be observed to slowly thrust out;
finger like portions of their substance in various directions, and even
move about slowly by means of a progre-ssivo flowing motion of their
own glairy substance, much like those remarkably simple animals found
in i)onds and ditches, and known to naturalists under the name of a»»-
ahw. In their movements, as watched under the microscope, two or
more blood-cells of the oyster may even actually flow together and be-
come conflueiit. Their function is in all probability of very much the
same nature as that of the analogous corpuscles found in the vessels of
higher animals, viz, to minister to respiration and the processes of
3 INT 21

822

FOSSIL OHTHKin^. 01' NOUTII AMK.nirA.

vitiil wiiHfo luid r»i)air. It is likely lliat tln-.v mo lonncd iiidirpctly
from tlio imtiitivo inattoiH wliicli liitvclMcn ii1».s<;i1k'(I IVom tlio looil
tliroii^'li tli«( walls of tlio iiitostiiio and Mtoniacli ; in fact, tiiin Hcctii)n8
often mIiow an almnilanco of similar corpuscniar bodies in tlio tissues
immediately adjoiniii},' the intestinal walls, tiie preseiieiMif wliieli in
Kiieli situations would seem to lio most ieadil,\ explained by the view
hero su;;;,'ested. Wliatover may bo tlio modo of tlieir ori^'in, tlieir
struct mo and ani(eboid climaeteristies would indieato that as they are
earned through the body of tlio animal by the blood current they take
an allimimrtant jiart in tho processes of prowtli and renewal of struet-
uro and tho oximlsiou of woni-ont or elletc materials, both liquid and
paseous.

The vas(!ular system of tlio oyster Ih not very easy to deseribo briotty
in an intelli;;iblo manner; in fact, it is not yet clearly understood in all
of its details even by jirofessed anatomists. The writer has, however,
traced tho princijial vessels and their connections with tho heart, body,
and Kills by a variety of methods, tho results of which will bo given
h'ro in outline.

The heart of tlio oyster ia a much simpler organ than that found in
man or the hifjher animals. It consists of three principal divisi(ms or
chambers, viz, a ventricle, partially divided in the middle line of tho
body by a i)artition or septum, and two smaller inferior chambers, ono
on either side, with darker walls than the ventricle. The - 'alions of
these iiarts to each other are shown in Fiji's. 1 and 2, at re ■ u. The

three chambers of the heart are lodjfed in a cresceiitshap* 'y juMt

in front of the adductor M and between the latter and llie oody-inass
in front, as may be seen in Ki^'s. I and 2. This cavity isclosed on either
siile by a thin membrane, which is rei)resented at c, in Fig. 1, detached
at its anterior border from tho body-mass and thrown imck over the ad-
ductor muscle. It contracts much more slowly than the heart of
higher animals, and even much more slowly than that of snails or gas-
trojiod mollusks. The normal number of beats of the heart of the oys-
ter in life i)robably does not much exceed twenty per minute, if its
pulsations are even so rapid as this. When fully distended the ven-
trido nearly tills the crescent-shaped s])ace in which it lies, but falls far
short of filling it when contracted. These two ojiposite conditions of
dilitatiou and contraction of the heart are rejiresented in Figs. 1 and 2.

The walls of the ventricle are very much thicker than those of the
auricles, and aro mainly comjiosed of muscular fibers, which interlace
with each other in various directions, and wliicih contract and elongate
simultaneously, so as to increase and diminish the capacity of the cav-
ity of the heart alternately, thus constituting a veritable living pump-
ing ai)paratus. This apparatus is rendered still more effective by rea-
son of the two valves which are interposed between the ventricle ve
and auricles au, the presence of which prevents the blood from flow-
ing back into the auricles from the ventricle when the latter contracts.

■rKKii 1

LIFK-lirHTOUY OF THE OVHTKR,

32 :i

TliOHO valvoH ivf tlii> lower cud of tlio vt-ntrido o|mmi upwiinlH, ho tliut
wo may roiilldciilly inC-r that llio lilnoil of tlio oyster tlowM eoiiHtaiitly
ill oii.'.linMlioii, or from tli<^ auricles tlir.Mi«li liie veiitrielo and from

♦'; ' tliroiiKh (ho Kreat posferior and anterior arteries a and «', to ho

dislriliuted to the o|t|io,site ends of IIk* Imdy.

Tlie liind.'rmost arl.'ry a carries frcsii l.lood mainly t(. tiic -reat miis-
cle ,1/, while the anterior one «' carries hloiKl to tliu hody mass anto-
Horly. After entering' the hodyniass at a' lllie anterior artery imme-
diately diviilcs and mci-N i. (h.rsal branch n' forward, ami a' ventral
brancii a" downward and forward; lliese two vessels are shown cut
iicros.M in the Ncelion represenled in Fi;,'.,). The tw«, main anterior ar-
terial iwiKs j,'ive otr many small hraiiclies at intenals which fravcrso
the soft Niilistance of tho body, but in some portions there seem to ]w
iio true vessels, but rather irie-fiilar vascular spaces whicdi in all proba-
bility communicate with the vessels Just described. The tissue in which
wo liiid more or less evidenco of tho existeiHH! of irregular blood-
Hpaces, is that indicated by tlio letter e in Fi- 3, and is tho lissuo which
envelopes all of tho internal oifjans, extending; even into tho mail-
tlo and gills. This common sni>portiiig or (ionneotivo tissue forms
tho walls of all tho great arteries and veins throughout most of
their c-xtent, especially when^ these traverse the soft body. mass, |.alps,
and gilK, A few of the vessels Iiavo proper membranous walls,
such a. I ho branchio-cardiac vessels br, Fig. I, which bring the blood
back to the heart from the gills, mantle, and roniil organs.

At the lower side of the body a larg(( vein, tho voim cava, vc, Fig. ;t,
receives tho blood from tho u|»per and anterior part of tho body to eon.
• vey it to thegills l(» bo oxygenated before it is returned to tiio heart
again. How tho blood sent from the heart to tho hinder part of tho body
is carried to tho gills and back to tho heart, tho writer has not been
able to mako out clearly. Tlioro is also a system of vascular channels
which traverse the adductor.

Tho arteries of tho palps are snpcrlicial, and arc shown in Fig. 1, but
in the dcci)cr, fleshy portions of tho palps, deflnito vascular channcLs
arc replaced by irregular vascular spaces. Injections and sections also
show that there are dcllnito vascular channels in tho maiitio and gills,
and in the former, cspe(;ially when tho oyster is very emaciated, thesd
KOiiK^times have very thick walls.

To sum up what wo have stated regarding tho courso of tho blood,
wo find that it passes from tho gills to the heart, thcnco to the various
parts of the bo.ly, and then .lircctly to the gillsagain. Itwill bo noticed
that this is an arrangement very different from that found to obtain in
fishes, where tho heart receives the blood from all parts of tho body,
sonds it through tho gill.s, and then on directly to tho various parts of
tho body. Tho difference between tho circulation of the oyster and that
of a warmblooded, air-breathing animal with a four-chambered heart is
still greater, from the fact that in such forms tho lieart receives the

324

FOSSIL OSTREIDjE OF NORTH AMF.niCA.

blood from all parts of the body, sends it to tbe lungs, receives it again
from tbe latter, to finj.lly again send it off to tbe different parts of tbe
body.

The food of tbe oyster is very various in cbanictor, as we find tbe
remains of small crustaceans, molliisks, larval worms, crustacean larvte,
rbizopods, diatoms, &c., besides inorganic eartby and siliceous mate-
rials, in tbe stomach. It is i)rol)abIy omnivorous, as U. Certes has hap-
pily expressed it ; the only condition which seems to he requisite In any
or^Miiic body to fit it for I'ood for this animal is that it shall be small
enou-j;li to bo passed tbrou^'b tin wide but vertically nincli constricted
montii and throat. The great bulk of the food of tbe oyster, however,
probably consists of minute marine larvic, infiisorians, and <liatonis, and
of these tbe latter, which are plants of microscopic size, are found in the
greatest profusion. The diatoms have very delicately and beautifully
sculptured siliceous cases, which encase tbe endochrome or living matter
which becomes the food of the oyster. The empty siliceous tests of
diatoms are often found in great numbers, mixed among tbe earthy
matters and debrin found in the intestine and stomach of the animal;
in fact mineral and indigestible remains of many thousands of individ-
ual i)lants may sometimes be found in a couple of grains of the fiecal
matters. The soft organic matter contained in tiie stony cases of these
microscopic plants is rapidly dissolved by the digestive jiJces poured
out by the liver, leaving behind the indigestible tests or c.s'^cs which
are carried out througk the intestine along with tbe ficcal inatters.

Tbe most of the food of the oj'ster consists of minute, living, moving
beings ; this is tbe case even with the diatoms, which are n.ii'ute vege-
table organisms endowed with the power of movement. The same sys-
tem of minute filaments which clothes tbe gills and ministers to respira-
tion by sweeping the water through the latter in a constant current, is
also the i)rincipal agent concerned in carrying the food of the oyster,
which floats in the surrounding water, towards its mouth, as is indicated
by tiie arrows below the palps in Fig. 1. When it has once reached the
palps, the inner surfaces of which next to the mouth are i)rovide(l with
narrow ribs or ridges, which are thickly covered with cilia, it is swept
down, or rather backwards, into the tiiroat, from the point m, which
marks the position of tbe mouth. The throat itself, however, as well
as the entire alimentary canal, is clothed with vilirating cilia, which are
tiie active agents in sweeping the refuse of the ibod and other ingestne
through tbe aliaicntary tract to expel it rit the vent r.

hi i'ig. 2, I'late LXXIV, the course of the alimentary canal i is indi-
cated, together with its relations to the liver /, in longitudinal median
section of the fore part of the body. Tins sketch was taken from an actual
dissection of a hardened specinK'ii ; l!io iigl:r lobe of the outermost iialp
and the soft parts of the right side iiavc I een removed in order to clearly
display the course and arrangement of tiie alimentary canal . The paral-
lel folds or ridges are sliowri on the outer surface of the inner p.dp or lip

BTUEU.J

LIFE-HISTORY OF THE OYSTER.

825

p ; it will be noticed that the ridges are wanting just a little below the
level of tlio mouth. The mouth m opens by way of a short gullet or
CBSorhngns into a very irregular cavity, which is the stomach. The in-
testine is continued Iroui the posterior portion of the cavity of the
stomach as a wide, somewhat irregular tube i' compressed laterally. In
the lower part of this portion of the gut, and extending to its (Irst bend,
a singular opalescent, hyaline caitilaginons rod, the crystalline style, is
lodged. Posteriorly, at the first bend of the intestine, a bluntly rounded
flnger-liko ventral process of the body-mass bm envelops the latter.
Beyond the first bend, the intestine i, as soon as it bends forwards again
towards the head, becomes more nearly cylindrical, and is continued
forwards over the gullet, bending down to the left side, and i)asses up-
wards, aft«r making an open bend upon itself, obliquely backwards to
end at the vent v.

The cavity of the intestine, along its narrow portion, is not really
cylindrical, as may bo seen iu Fig. 3, rei)resenting a cross-section of au
oyster, viewed from the anterior side, and taken from a specimen in a
plane corresponding very nearly to the lino o in Fig. 2. In this section
the intestine is cut across twice, as shown at i' above and at i below
the stomach. These sections show that the intestine proper has a pecu-
liar crescent-shaped cavity, when cut straight across, which arises from
the fact that one side of the wall of the intestine has been pushed in-
wards towards the other. This peculiarity characterizes the shape of
the cavity of the intestine from its first bend to its termination at the
vent.

The only glandular ai)pendage of the alimentary tract of the oyster
is the massive liver. It communicates T\'itli the stomach by means of
a number of wide ducts with somewhat Iblded or plicated walls. The
great ducts subdivide, and their ultimate ramifications terminate in a
multitude of minute oval follicles, which are the effective agents iu
secreting the biliary and peculiar digestive juices. A thick stratum of
these foilicles surrounds the stomach except at its back or dorsal side.
The extent or distribution of the liver I iu the body-mass, and the way in
which it is imbedded in the connective tissue c around the stomach st,
may be inferred from Fig. 3.

The function of the so-called liver of the oyster is evidently digestive
and probably combines the action of a gastric, j)ancreatic, and biliary
secretion. There are absolutely no triturating organs in the oyster for
the comminution of the food ; it is simply macerated in the glandular
s.cretioa of the liver and swep;, along through the intestines by the
combined vibratory action of innumerable fiu() filaments with which
the walls oftho stomach, hepaticducts, and intestine are clothed. There
is no peristaltic action of the intestine and there are no annular muscles
in its walls. The nutritive matters of t!ic food are acted upon in two
ways : first, a peculiar organic flTuicnt or solvent derived from the liver
reduces it to a condition in which it may be absorbed ; secondly, iu order

p?p

326

FOSSIL OSTREIDiE OF NORTH AMERICA.

tbat absorption may bo favored it is propelled tlirough the intestinal
canal, wliitjli is peculiarly constructed so as to present as large an amount
of absorbent surface as possible.

Tlie expulsion of efleto matters in the oyster, beside fajcal matters, is
accoiiiplislied by tlie r,:spiratoi'y system or gills and the organ of 15o-
janus. The llrst is concerned simply with the eliininati. n of tiie gase-
ous products which are a result of the vital actions of the animal, the
latter apparently with eiVete matters more or less nearly similar to the
urinary excretions of higher animals. To what extent the liver may be
excretory in function it is not possible to state.

The organ of Eqjanus, a structure which appears to represent the
kidneys of the higher animals, is an inconspicuous organ in the oyster
as compared with its develoj)ment in some other lamellibranchintes,
such as the fresh-water mussels. M. Dock, of Leyden, and the writer
have been the first to definitely locate and describe this organ in the
oysters of Europe and America. It consists of a crescent-shaped mass
of tissue, indicated by the area hj in Fig. 1, lying on either side, Just
below the insertions of the adductor muscle .1/. In structure it is spongy
and canalicuhited aud very possibly glandular. It lies close against
the mantle on either side, and, in fact, extends somewhat into i(s sub-
stance. M. Uoek has traced the connection of this organ in the Euro-
pean oyster with the pericardiac cavity and the oi)enings of the genera-
tive organs s, on either side of the ventral process of the body-mass/,
shown in Fig. 1. The connnon openings of the general ivo organs and
the organ of Bqjaiuis will, therefore, probably have to be regarded as
urogenital outlets.

The sexes are confined to distinct individuals in the American and
Portuguese oysters, but the connnon oyster of Europe is clearly herma-
phroditic, that is, the two sexes are more or less evidently combined in
the same individual. The mature ova of the American and Portuguese
species are of about the same size and measure about one five-hun-
dredth of au inch in diameter, while those of the common European
species are about one two-hundred-and-flftieth of an inch in diameter.
In the latter we may find the male and feniale elements developed side
by side in the same ovarian follicles, but it also ai)pears that there is a
preponderance eitherof eggs or of spermatozoa developed in many indi-
viduals, so that some are even i)ractically unisexual.

The reproductive organs are actively developed for only a compara-
tively short time, extending over a period of i)rol)ably two or three
months. In the region of the Chesa])eake the most iiiniortant spawn-
ing period s'cms to extend over the months of June and July, but con-
siderable rii)e spawn may be found oven nuich earlier and Inter than
this. Individual oysters may bo occasionally found at almost any
season of the -ear with spawn more or less far advanced or quite ma-
ture. It is not uncommon to find the reproducMve organs far advanced
in respect of functional development in the early spring months of

BTDEa]

LU'E-IIISTOEY OF THE OYSTER.

327

March and Ajjiil. Upou examining large uunibers of individuals at the
same period, it will be found that while in many specimens reproduc-
tive activity has quite ceased, in others it is still in active progress.
This variation is doubtless due to variations in the amount of food and
to favorable temperature conditions, but it is in the highest degree
probable, jidgiitg from the appearance of the spit, that comparatively
few embryos ever develop so as to come to anything, except during
the siunmer months.

Thcsuperlicial extent of the reproductive organs isquite considerable,
as may be inferred from an inspection of Fig. 4, which represents the
soft parts of an oyster viewed from the left side, to display the ramili-
cations of the generative ducts of the left half of the body, and the
ontk't below the muscle at or. The generative tissue Qtn, in this figure,
is distributed over the surface of the body-mass as a thick, creamy
white, superficial layer which covers the greater portion orf the latter.
It really consists of a multitude of little sacs or follicles embedded in
the connective tissue, which open and pour their contents into the su-
perficial brandling ducts shown in Fig. 2. The mature i)roducts are
l)oured out of the large oviduct ov, which empty into tlie water space
above the gills, tlie current from which passes out of the shell by way
of the cloaca d (Fig. 1), which carries the generative products outward
into the open water in the ease of the American and rortugueso species.
In these two species the impregnation appears to occur outside of the
parent in the open water, where the eggs and milt encounter each other
from individuals of different sexes, but in the common European species
the unanimous testimony of observers is to the efl'ect that the young
are retained within the parent shell, adhering in masses to the mantle
and gills, where they undergo a kind of incubation, prior to being set
free to shift for themselves. This is a remarkable difference of hiil)it,
and one whi(!h would alone serve very well to discriminate the two forms
from each other. The embryos of the hernmphroditic species are about
twice as large in diameter as those of our native and the Tortngueso
speciies, owing to the fact tliat there is about the same diliereuce in the
size of tlie mature ova of the two types.

It is remarkable that we should find the reproductive organs of the
oyster mu(!li more developed in some individuals than in others ; infact wo
may find them apparently wantingaltogether in some specimens after the
spawning season is over, or, on tlie other hand, forming, in the height of
the season, a layer over the outside of the body-mass more than a fourth
of an ineli in thickness in some i)hices. In an undeveloped condition
the generative ducts and follicles form an open network which traverses
the connective tissue. The relations of the generative tissues to the
other organs is very well shown in Fig. 3, where ge indicates this layer
moderately developed, as seen in a cross-section. Judging from the
many observations made by the writer, it is evident that these organs
diminish greatly in bulk, or disappear entirely after the spawning season

328

FOSSIL, OSTREID^ OF NORTH AMERICA.

is ovei , tt probably again develop to great proportions by tlio time the
next spawning season arrives. The organs also vary with the size of
the individual, and a large female American oyster may contain more
than 1()(),0()(),000 ova ; a small one, 3,000,000 to 4,000,000, or less. They
begin si)awning at one year old.

At a temperature of 75° to 80° Fahr. the period of incubatiou of the
American oyster is only five to six hours, when the young commence to
lead an independent active existence, which is in the most striking con-
trast with the permanent sedentary habit of the sitat and adult condi-
tions. In the European oyster the young are retained in the folds of
the mantleaud about the gills of tlic parent for apparentlya much longer
time, the length of which does not, however, yet seem to have been
determined.

The young, when first hatched, are ovoidal In form, not much, if any,
larger in bulk than the egg, and they have a slight depression on the
back or dorsal side, which marks the position of the shell gland or first
rudiment of the mantle organ properly so-called. Here, as development
advances, the shell is formed as a very thin saddle-shaped structure,
the right and left lobes of which grow in size with the development of
the embryo. Soon these two halves of the larval shell become very con-
vex and cover the soft parts of the young oyster on eitlier side almost
enlirc'ly ; the mantle m and velum v alone projecting somewhat past their
margins, as shown in Fig. 1 in the accompanying Plate LXXV, which
rei»resents a young American oyste- in the larval or fry stage enlarged '250
times. The velum v consists of a cushion-shaped anterior projection of
the soft parts, which bears two circles of long, very minute, thread-like
appendages or cilia, which are incessantly vibrating, and which con-
stitute the locomotive organs of the fry. The rapid movement of these
filaments propels the young oyster through the water, and probably
also carries minute particles of food to the mouth, situated immediately
below the velum. The intestine and stomach are developed by this
time, and there are also delicate muscles formed which retract the velum
mn\ draw the valves together.

A portion of the nervous system is developed in the center of the
velum, which answers to the supracesophageal ganglion sg, Fig. 1, Plato
LXXIII (of tiie adult), which consists of a pair of knots of nervous
matter, which lie above and at either side of the mouth, and which are
connected on either side of the body by a commissure or nervous thread,
with the larger hindmost ganglion i)g below the adductor muscle. The
mantle border is innervated from this hindmost nervous mass, and radi-
ating threads pass out from it on either side in all directions to the edge
of the mantle and tentacles. The nervous system of the fry or larva; is
much simpler than that of the adult, yet they are apparently sensitive
to external stinudi, such as raps or blows struck on the table on which
the microscope rests under which one is observing them.

The duration of the locomotive stage of development of the larvte

■tr

■^f"

• i I

RTUIIt.J

LIFE-HISTORY OF THE OYSTEE.

329

Las not yet been certainly determined for any one of the luiee species
of which the development has been studied. In the case of the Ameri-
can species, however, it has been found by the writer that under favor-
able circumstances attachment of the fry probably takes place within
twenty-four hours after fertilization. This appears to be effected by the
border of the mantle of the fry, where it is deflected over the edge of
the undermost valve, as represented at m, in Fig. 1 of Plate LXXV.
The attachment is a close one to whatever surface the fry may fix itself
and at most, if there is a byssus developed, it is extremely short. The
young, however, after attachment, continue to grow as larvse, and have
a very symmetrical shell, as shown, enlarged 90 times, in Fig. 3, in the
plate. When the valves of the fry have acquired umbos the develop-
ment of the spat shell begins, as shown in Fig. 4, in the plate. The
spat shell is, however, different in its microscopical characters from that
of the fry, since we find that in the spat shell, or in that formed after
permanent fixation has been accomplished, the calcareous matter begins
to be deposited in a tesselated or prismatic manner. The transition is
a very abrupt one. The larval shell is homogeneous, but the calcareous
material of which it is composed is laminar in arrangement. As soon
as they are formed the beaks of the larval valves are invariably inclined
upwards in the spat, as may be seen in Figs. 5, 0, and 7, viewed from
abo\e, and in Fig. 9, as seen from the side, in the plate. It is also a
fact that the beaks of the larval shells are invariably directed horizon-
tally in one way, as may be seen from the same series of figures.

For a considerable time the whole under surliice of the lower valve of
the spat remains flat and is cemented to the surface upon which it is
fixed by its under side. It is only after it has grown to the size of from
one-half to two inches across that its margin begins to bend upwards and
become free. The cementing material seems to be the organic matrix
of the shell which forms a perceptible layer on the outside of the valves,
and which constitutes tlie epidermis or periostracum of the adult.

The history of the fixation of the common European oyster does not
seem to have been very well worked out. but it is probably not very dif-
ferent from that of our own species. The young of the former, however,
as taken from the beard, or mantle and gills of the parent, vary consid-
erably in size, as may be inferred from an inspection of Fig. 2, in the
plate, which represents four specimens enlarged 90 times, drawn to the
same scale, in different positions, and taken from a preparation in the
possession of tlie writer.

In order to show the rate of the growth of the spat or affixed stage of
the oyster the following figures may be useful : That represented in Fig. 5,
Plate LXXVI, is supposed to be not over twenty days old; that in Fig.
is known not to be over forty-four days old; that in Fig. 7, not over
forty-eight ; Fig. S, seventy-nine; and Fig. 9, eighty-two days old. Fig.
10 represents an oyster of one summer's growth, collected from a wreck
at Cape May, N, J., by my friend, Mr. John Ford. The preceding figures

330

FOSSIL OSTREIDiE OP NORTH AMERICA.

except the last one, are taken from spat which had fixed itself to and
grown on tiles placed in the water in the vicinity of Saint Jerome's
Creek, Maryland, during the summer of 1880. These tiles were placed
in position at determinate dates so that the age of this spat was ap-
proximately known. Tlie figures are of the natural size.

Some of the same lot of spat here figured was placed under favorable
conditions, and, in the space of twenty-two months from the date of the
fixation of the fry, had grown to a length of 3iJ inches, though the shell
was still c( iiparatively thin. From this fiict it is fair to infer that in
about twice that time, or in about four years from the egg, tlie oysttr
is approxinmtely adult and marketable. In their best condition they
are probably usually older than this, however.

The notion that the oyster is not edible during the so-called unsea-
sonable months is not well founded ; they may in fact be eaten at any
season of the year, if fresh, wituoutharm. In fiavor, delicacy, and fatness
the oyster is not as good in summer as in the colder months, but beyond
this there is no great inferiority. The so-called fat of the oyster is not
the spawn or engorged reproductive organs, but the connective tissue,
indicated by c,in Fig.3, Plate LXXIV. This connective tissue acquires a
peculiar creamy whiteness during the winter months, together witii a very
considerable augmentation in volume, so that the mantle, especially that
portion covering the body, becomes very much thicker. In summer, on
the other hand, in consequence of the large amount of material whidi is
used np in tlio development of generative products, this same tissue
diminishes greatly in volume, and at the same time loses its creamy-
white appearance and becomes transparent or translucent. At the
same time, the minute structure of this same tissue acquires a some-
what ditlerent character from that observed in the fat condition, becom-
ing looser or more areolar in appearance as seen in thin sections.

The waters in which oysters normally thrive are those where the bot-
tom is pretty firmly fixed and not liable to sudden change. The crea-
ture belongs to what is called the littoral or shore fauna, and I doubt
•whether many extensive beds exist in waters more than 18 to 20 fath-
oms in depth. The range of the American oyster, according to Verrill,
is from "Florida and the northern shores of the dulf of Mexico to
Massachusetts Bay ; local further north oil" Damariscotta, Me., and in
the northern part of the Gulf of Saint Lawrence, at Prince Edward
Island, in Northumberland Straits, and Bay of Glialpur. Xot found
along the eastern shores of Maine, nor in the Bay of Fundy." In the
Chesapeake, wliere all the conditions are favorable, the oyster is found
more or less abundantly in the most of its tributaries, many of which
are estuarine. The '< coves " or inlets in the Chesapeake are largely of
the same character and are aliected on account of their gieat width, in-
considerable length, and free connection with the bay^ by the tide to
their very heads. In the great rivers, like the Potomac, which flow into
the bay the oyster beds are also extensive and important industiially.

BTDER.]

LIFE-niSTORY OP THE OYSTER.

331

The sandy beaches of onr coast are unfavorable in many places for
the growth of oysters, although many important beds exist ou our
Atlantic coasts in favorable localities.

The water in which oysters exist may be almost entirely fresh, and it
is doubtless a fact that in some cases, the water i)assiug over the beds
in certain situations at ebb tide, as in rivers, may be absolutely fresh, a
fact noted by Semper in regard to the oysters of the Cnuiidaran Uiver,
at Basilan, south of Mindanao, in the East Indies. Tlic hydrometer, in
some places where tliere are extensive beds in the Chesapeake, stands
at 1.007, and ranges on up to about 1.020 at the mouth of the bay, but in
places still higher up the bay than that where our lowest hydiometrio
observation was made, the specific gravity of the water must bo even
very much less, so that in such places where fresh water is received
from considerable streams from the land, and where oysters are known
to exist, the water must often bo almost or altogether fresh for hours
together. The precise degree of saltness of the water most favorable
to the growth of the oyster has not been determined, but to judge from
the circumstance that most of the oysters which go to supply our nuir-
kets come from the great bays, rivers, and estnarine tributaries of the
coast it is fair to infer that such waters, which almost always have a
less specific gravity than those of the open sea, are the natural home of
this mollusk.

American as well as the European oysters sometimes acquire a pe-
culiar greenish color in certain parts of the body, especially the gills
and ventricle of the heart. These are always tne first to be allected.
A very careful investigation made by the writer has resulted in show-
ing that it is the minute blood-cells which become tinged with a greeu
coloring nuitter, and that they then tend to lodge in the heart and gills
in great numbers, thus giving rise to the green appearance. The col-
oring matter, whatever it may be, is harmless, as it has never been
shown that it is a poisonous compound of copper, as has been errone-
ously sui)posed. It is very pos.sil)ly derived from some vegetable color-
ing principle taken with the food, or it may possibly be an abnormal
product of the digestive i»rocess. It is ecpially certain that this green
coloration is not due to the presence of a vegetable i)arasite.

lieceut experiments have tended to show that it is not improbable that
both the American and Portuguese oysters may be reared in very much
the same way as fish are bred from their ova. Tlie exi)eriments of JI.
Bouchon-Draiulely, in France, and of Colonel McDonald and the writer,
in this country, show that such a method is probably feasible. The
writer has shown that the eggs may bo very expeditiously extracted
from the oyster somewhat after the method employed in taking the ova
from fishes, lie has also devised a method of distinguishing the sexes
apart, so simjde that the distinction maybe made witliout even the
use of a pocket lens. The eggs and milt after the removal from tho
parent animals, may be poi;red together, iu order that fertilization may

332

FOSSIL OSTBElDiE OP NOKTH AMERICA.

take place. After a few hours have elapsed, these embryos may bo
poured into suitable inclosurcs, into which the sea-water may enter and
escape without carrying oflF the embryos themselves. In such inclosures
in wliich tiles coated with lime have been placed, it has already been
demonstrated that the embryos or fry will attach themselves to the tiles
and become transformed into young spat. As many as four thousand
have been found adherent to one tile, as a result of such experiments.

During the present season the writer has successfully reared the spat
of the American oyster in a pond constructed on the premises of Messrs.
Pierce and Shepard, near Stockton, Worcester County, Md. This pond
was dug out of a salt marsh; its depth was three feet and a half. It
was connected by a trench with Chincoteague Bay, adjoining. Into the
trench a wooden diaphragm was tightly fitted and filled with sharp
sand to filter the water passing into the inclosure, and to prevent the
escape of the artificially-fertilized embryos of our native species, which
were introduced into the pond at intervals during the month of July.
In forty-six days after the commencement of this experiment we found
spat measuring three-fourths of an inch in diameter attached to the old
shells which had been put into the pond to serve as collectors. This
experiment proves that artificial oyster culture is feasible in the United
States, and that marsh lands may become valuable where the adjacent
waters are of the proper density.

The shells of the oyster are very irregular in form, in fact, scarcely
any two individuals are to bi^ found which are precisely alike. The
typical form of the shell of the American oyster is very well shown on
Plates LXXVII and LXXVIII, and is in fact the form most desirable in
the estimation of the grower and dealer. Other varietal forms are,
however, met with which diverge pretty widely from this one, as may be
inferred from the type represented iu Plate LXXIX, where the lower
valve is short and very deep. This second form is not a very usual one,
but aptly illustrates one of the extremes of variation of the species.
Another type now regarded as a variety of the common American oyster
is represented on Plate LXXX, and was formerly supposed to be a dis-
tinct species under the name of Ostrea borealis; the name having refer-
ence to its more northern habitat. Its most characteristic conchological
features are the deeply fluted valves; usually the lower one is the
most deeply fluted, while the upper one is nearly smooth, but sometimes
specimens are met with which have both valves very distinctly and
quite deeply fluted. Of this form Verrill remarks, " Even the same
specimen will often have the form of borealis in one stage of its growth,
and then will suddenly change to the Virginiana style, and perhaps,
later still, will return to the form of borealis. Or these difi'erent forms
may be assumed in reverse order." Lastly, a type of oyster is met
with in deep water or in crowded banks which has the valves abnormally
elongated as represented on Plates LXXXI and LXXXII, and knowii
as the raccoon or cat's-tonguo oyster. This elongation of the valves

riviiKfi.l

J.IFE-H18T0RY OF THE OYSTER.

333

ia duo to crowding, and also to the sedimentation or silting of sand
or earth between such individuals as grow closely together on the bot-
tom. In the struggle for existence the animal is impelled to grow up-
wards from those causes in order to reach its food and the water nec-
essary for respiration. Consequently the shelly deposit is laid down by
the mantle mainly at the free ends of the upwardly directed valves, so that
the latter grow only in lengtli and not in width, thus giving rise to the
extremely elongated typo often met with. Such a form sometimes pre-
vails over a whole bed, and the valves are often relatively very thin in
consequence of the rapid growth which has been made in only one
direction. In this form the animal or soft parts are also much elongated
antero-posterioriy,so as to bo quite ditli'rontin shape as comj)ared with
the soft parts of an individual, such as that of which the shells are rep-
resented on Plates LXXVII and LXXVIII.

834

F0881L OSTHElDiE OF NORTU AMERICA.

EXPLANATION OF PLATES.

PLATE XXXIV.

OsTKi'.A i-ATi;i!Ct'i.A Wiiiclii'll. (riigo288.)

1"I0. 1.— Interior view of tlio lower valve of the type H))eeinien; natural bIz«.
a,— Lateral view of the sanio speiinieii. After Wiuchell.

OSTHKA ENOELMANNI Mcelc. (PaKe289.)

n.— Exterior view of a lower valvo; natural »lzo.
4. — Interior view of another example.

f. If. ■iKiiuimiM, Fiiivrv

Ayvrii. iipi'mif i«sn im xxxtv

(',Utli().\in:i!()i s A\i> ji-iiASsie

aae

FOSSIL OSTREID^ OF NORTH AMERICA.

V /

Fig. 1

9,
10,
11.

PLATIO XXXV.

GuYPii^A CAI.CEOLA v;u. NF.i.iuscKxs/s Mcck & Ilajdeu. (Pago 290.)

.— r,.\tciior view of a loucr valvo ; naliiial size.
'■—I ateriil viow of anotlior lower valve.
I.— Iiitorior view of tlie same exaniiile.
.—Upper vi.'W of a small example.
'.—Interior view of an npper valve. Aftei »,reek.

OsTHEA (Alkcthyonia) ntccu.MiiKNs White. (Pi,goS90.)
.—Interior view of a lower valve ; natnral size.
.—Lateral view of tlio saiiio »peeimeii.
.—Interior view of an ni)per valvo.

OSTKEA .STKIGILECULA Wllito. (Pagc989.>

—Exterior view of a lower valve ; natural size.
—Lateral view of the same specimen.
—Interior view of an upper valve.

V i

I. «.

^'illl.O(,ICAL eiilVICV

'^rr%?^.

'^■VM-AL KProui 1SS3 1... xi;,,.

iUJ

JL'RasSIC.

3 INT 22

888

FOSSIL OSTREID^ OF NORTH AMERICA.

W '

Fig.

PLATE XXXVI.

OSTHEA COALVILLKNSIS Mcek. (PllgO 293.)

—Exterior view of an upper viilve ; natural size.
— Interior view of tbo eanie example.
—Exterior view of a lower valve.
—Interior view of the same example. After Jleek.

Osti{|;a ELt;oAN'TULA Newherry. (Pago 295.)

-Exterior view of an npper valve; natural size.
—Interior view of (he same si)ecimen.
—Exterior view of a lower valve.

'i»<!.ise»es»uii*»aow4a**BwA!K .jfc.»ii(

) »

340

KOSSIL OSrUKID/li OK NORTH AMKHICA.

^ I /

PLATE XXXVII.
OsxnEA sunspATULAiA Forbes. (Page 301.)
Fia. l.-Lateml v .ow of a separate valve ; natural size.
2.-I.,terior view of the same example. After Forbes.

OsTiiEA coiiTKx Conrad. (Page 294.)
:t.-Extcrior view of a separate valve; natural size.
4.-Siniilar view of another speciiu 3.1. After Conrad.

OsTliEA PLUMOSA Morton. (Pago 299.)

5.-lIp,,er view of a specimen somewhat distorted by pi^ssuro ; natural aize
C.~E,tenor view of the upper valve of another example.

I-

BIB

UtOWMOMfc*.

t. K. ciKcll.Di.ll Al. hi I1M;»

A\M .\r. IIRI'dllT \>iK.\ IM. XWMl

t liiriAcKor

-^m

■I

342

vomL (mnv.wjE oi- noimh amkkica.

I'I'ATi; .\.\X\III.
OsTiiKA Ml i.TiMitAT.A Conrad. (I'.itii'y'JH.)
*'lae.l,'.'.-Exfcrior views n,-,w, lor-nr, ox,u, ; natural Mzo.

I • iiKOI.riiili Al. kl'KVUV

ANNi II. nFi'i'iir IKHM 11 xxxvill

I i!i;i.\(i;<i("<.

344

l-OSSIL ().STI{i:il).E OF NOinil AMKKK'A.

•!•

I'lGS, I,

10.

11.
1.!,

I'l.ATi: XXXIX.
OsTnnA ki;anki.i.vi CViMiinil. (I'a;;,, 2;iil.
■■i. :!.-Vi,.w8 of threo ,liflWe„t oxa.nplus; natural .size.
asritUA A.vo.MioiDics Meek. (I'ago'J!)!.)
I— L.-worvalvo; ,..<(,., i„r viow; natural si/o
^— Similar view of an npper valve.

OstI!i:a |)kli.a Conrail. (PaseaOv;.)
.-Uiiner view ; natural size. After Conr.nl.

OsTiiEA iDnroExsis Gabb. (I'agcaot;.)
—Upper view ; natural sizts
—Interior view of an under valve. After Gabb.

OsrmcA Al'PiiK8.SA Gabb. (Page 291.)
-Upper view; iiatuial size. After Gabb.

O.STHKA SU1!AI..VIA Meek. (I>age;!00.)
-Uiiper view ; natural siz.>. After Meek.

O.STliiCA co.VGKSTA Coiira.l. (I'age2!>4.)

After Owen.

"■'■'''irllr'-^-^'"-'^^ "•''^•"■•' '"'' '-^" -^"'« «'■•■>• or a large

13. -Interior views of upper valves. After Meek.

'' ' ''■i^''ljgafcL„jtMMii>ij!^j^

U. X. liEW.OCilLAI, KCIIV

VNM'Ar. IlKmiM lt.K3 I'f,. NXXIX

•■H'':iA(i:iiis

1 I

34G

FOSSIL OSTREID^ OP NOB' AMERICA.

PI.ATK XL.

OsTliHA DII.UVIAXA LimiiUMS. (PHgo29,->.)

1-iO. l.-Lateral vi..„- ; „,.t„r,al Hi.o. V„r „H,r,. vi.ws sec no..t ,.l,.t„.
OSTIIKA C1:HXUMMAI!GIXATA Gabb. (Paso204.)
a.-lMtcrior vi.Mv „r „,„ ,„„.cr valv,. ; n,.,v„al size. Aft,.,- Gal.b.

OsTiiiCA KonusTA Conrad. (Pago ;!00.)
;!, l.-OppoHite vicwH of Conrad's typo speci.nen. After Conrad.

OSTRKA IMtUDlSXTIA White. (Pagi, 099.)

5, C-Opposito views of one of (ho type specimens; „..l„r,a sizr.

■ ti»

WBO

■ vb

CKl'.lAl l:(H,B,

— ^^^^

a48

Fossii, osri;i;ii).r. oi' \ iimii amtkica.

I'l-ATK Xl.I.

OSTREA DII.rVlANA LilimcilS. (Vixirv U'Xi.)

Fios. 1,2.- -Kxterinr mid intfiior vicwaof tliiMipper viilvc; iiiitiiralHizc. Foralatoral
view (if tlio same pxamplo sec Plate Xly.

OsTEKA i.uouiims Cdiirail. (I'ago2t)7.)
3.— Exterior view of an under valve ; natural size.

'f i

» ,

r. «. >il{lll,(ii.lr.\l, hTH^H

AVM Al. I!l Tdlir !«►:! I'l.. M 1

( iiK! A( iXirs.

IMAGE EVALUATION
TEST TARGET (MT-S)

1.0

1.1

11.25

1^12^8 |2.5

u, lis "^
£ in i2.0

1.8

U. 1 1.6

Photographic

Sciences

Lurporation

23 WfS? MAIN STREET

WEBSTER, N.Y. 14580

(716) 872-4503

>..

■^

'^fc

■I

'■

.1. •

?i!

mmss.

iUO

FOSSIL OSTKEID* OP KOBTB AMERICA.

PLATE XLII.

OsTnEA flOLENiscus Mook. (Pago 300 )

OSTIIEA (AI.ECTUVONIA) LAIIVA LaM.arck. (Pago 296 )

V. S. ' EOl.OUlCAI. HI'IIVRY

CliKIACKol's.

■;t

I' 4

352

FOSSIL OSTUEIUiE OF NOUTII AMEKICA.

PLATE XLIIL
OsTRKA CAHINATA Lamnrck. (PageaOS.)
PlO. L— A largo example; natural size. After Rmmer

a. 3, 4.-Throo different view, of a smaller example ; aUo from TexM.

OsTREA guABRiPLiCATA Sliumard. (Page 299.)
5.-Exterior view of a lower valve having „„„H„„„y p„„.i„,„t ,„^^, „„j„^^,

6,7.— Copies of Slnimar<l'.s original flgtires.

OsTREA CRBNULIMAROO Roeuior. (Page 294.)
8, 9. -Copies of Roomer's original figures ; natural size.

-iE-

I". «. fiEniiiiii,

AV\I 11. I:KI'Ii||I |.«S'|

CHliiACliOL'S.

3 INT 23

354

K<i«<sl|. •»riil l|),t; ••!• XoKTH vMKincA.

I' VI K M.IV

Oi<TI!I:A I1.\I;1!.\N1i|:| I'ui|1|.ii;iI. \'.f^<-i.>'J.)

Klo 1.— Kxtciuii vii'W 1)1' ihu liiwi r Milvi.'i |]iiiiii:il ni/.i'.
M.VI.

.1#

I'. ». (,K.iiMi<ii< II, m iivrv

AINI'AI. HKI'CIHI IHKI I'l.. \ll\

rACKdl'S.

^ »

356

rOSSIL OSTBKIDiE OF NOBTH AUEBICA.

PLATE XLV.

08TRKA ULACKH White. (PageiOi.)

PlO. 1.— Upper view ; natural size. Kor aimtber view see next plato.

08THKA lUItllANDKI CoquaiKl. (PaiTea92.)

'<!•— Interior viovv of (ho lower valve. Kor other views see Platoa XLIT and
XLVI.

OSTRKA (ALECTRYOXIA) SAX.VIONIS White. (Pago 300.)

3,4,5. — Exterior view of throo ditloront valves; natural size.
6,7. — IntiM ,ir views of a right and left valve.

•M

I". K. MMlincii \l. hi l!\ l-V

ANM AI, IMI'iMd 1^>.'! IM.. XI.V

CKiriAlKOl'S.

u i

858

P0S8IL OSTRKID* OK NORTH AMERICA.

PLATE XLVI.

08TBKA BARHANDEI C'oqUJind. (Pll|Te s!92.)

FlO. I —Exterior viow of the iipiicr valve. I'l.r dIIut vicwh mo I'hih-.i XLIV anil
XLV.

OSTREA IILACIUI WllitO. (Pllgoa'J-J.)

a.— Exterior viow of the under viilve. Tor Iho opposite viow »e« I'lutn XLV.

V, B. USOLUUIIAI. itLKVKr

ANXLAI. IIEI'OIIT 1883 I'L. XlVl

CUIiTACEOL'S.

\ I

aeo

roHHii. osimwM of noutu amkuica.

i 1

PLATE XI.VII.

OsTiir.A riri.i.iPi.u'ATA Slniinnnl. (PiiRoaQB.)

Fin. 1.— Kxfrridi view of tliu nndnr side ; imdiriil hIzp.
a.— Lateral view of the snnio examplo.
3. — Extorinr view i)f tlio upper valve,

OsTliKA I'ATINA Meek & Haydnn. (Pngo 298.)

'(.--I'xtorior view of an upper valve; natural HJze.

•1. — Similar vii'w of a lower valve.

t).— Interior view of the Niinic exami/lc After Meok.

U. H. i.F.'il.iii'K tl. Kl ll\ KV

1-5' . *

AVM-.vr. iiri'niiT ifH:i ii yi \ u

Clii:TACi:i)rs.

K^ijs^tesiiJKsweii^ttiw*^****

wmm

3(;-_>

I'OSMI. OSIKIMIM, or NOIMII AMl.KlrA

l'iii>. 1-,".. -Dill,

I'l.Aii; xi.viii

(.ItVI'll 1 A V1,.M> I I.Al;,^ I ,,,|.,,|^ ,l\.-,.;ii:!.i

II"' virus. ,|-„.|,,„:,lr v:,Urs: „mI „,„ ; .si /,■.

Osini'A 1

MI.HIMIS .M..,.U. J I',

li.T, -r

«c. \ i,\Vs , if 111,. 1,1

I'l- i.llVf 111' M cl^'s t

Vji,' S|M',iiii,.ii : li:lIiM:il

OsTur.A Vi>\ii:i! .M,.ri.,ii. ,1

i.l':\;,',' :ilH.

•*-10.--nillrivnt

vi,'\\>.; naliiriil si/t"

mwsSimiismsm

ifg^m'-y Ti'u^'isiii

'■I I'l o..lt \1 ^1 |;\ I \

VNM \1 IMIVilil ISS:! IM . \1,\ Ml

cKKTAriiiirs.

T -jg- i'i ;,!

"'■» iiiailiutiiiilinil

^tiT^rrr Tiiiggl

I ,

864

FOSSIL OSTKKID^ OF NORTU A^rKRICA.

I'l.ATK XLIX.
tiiivrii,i;A iTiciiKHi Jforton. (Pnge30!>.)
F,G8. 1, 2.-TW.. vK.ws ..f au oxa,u,,le ......vpi,.,,, t„nn, natural size.

3.-I,,tenor v.e«- of ,l,c Unu-r valve ola y.r- largo exa.nple

« J 4

I )

^ '

•r^

.1,

866

r<>.SS||. (ISTKKUMC Of NOKTH AMKK.fA.

ri.AiK 1..

I'.XiMiMiA IMNDI-.IIOSA l;,.clll.-|-. (l':lg.' ;iOl).)

Kios. 1. 'J. -r|,,„.,inul iii:ar,\i,.«.„|;,.M.SMUi|.l.M.|;,lH,ut lialf (nil ii<hllt size. .Ut«
h'Mi'iiin'.

Omi:i;a ti:( i [...ma i a CuM,. ( l';l^,. liul.)

;t.— A cliistiT of \alvrs: iialiiral .si/r.
4,— Iiiti'iioi' vii'W ola Inwci' valve.

Osnii: !'|.:i.i.icii>A Mecli A llayd,'!!. , I'aj;,. v'!'il. )

.■>.— Kxtciidr viiw Dt'a low.-i- valvr ; natural fi/.r.
ti.— Oppositf vii'w of ih,. f^anic ixaiii|ilc.

OSTiu'A MAii.i:iK()H.Mls (ialil). d'ayi' 'J'JT. )
7.-Kxt<.riiir view of an iippiT valve; natural size. After Gabb.

. t

'ti'

tl!I'.TAli:i)ls.

1 '

■I

3(iH

I'OSHII, OSTIIlulD.V. nr NOIJTII AMI.I.'ICA.

I'l.ATi: M.

K.VnOVIlA TKXANA li'llilllcr. (I'llH" liOti. )

Fias. 1,'J,:!.— rp|M r, undi r, and liiliial vicwHdfa iiriuiy iidiill cxaniiilc ; iialiual m/.v.
■liTi. — Interior vinWH (pf Ihc niidi i and iipprr valvi'S id' tin' ■■aiiH' i\aiiii)li>.
AI'liT Ka'inor.

i I

|l. ». llHi|lli,|l\I M IIVf>

^^M \i iri'niM \"-\ n 1 1

rlii:iAc Kui-s.

•?r— r

I V

■ ,j..iK.i:,im.r;c^ ■ ■■:■ :.y .n-nr:

,T INT I't

370

FOSSIL OSTREIDiE OF NORTH

AMEniCA.

PLATE LII.

E-XOOVHA I-Oa.V.CULATA Wl.ito. (P,... ;,„5 )

HOS. 1. ..-Exterior a„.n„..H,,r View, of , U„ ..,,,. r valve , natwra, «i.e.
K-xor.v,u r.^,v,u.scuLA R,.,„e,.. (Pa^o m )

KxoovKA w..vcnK,.,.Mvi,it... (Page :!07.)
'^' — J^xterior and intirinr x-;,.... .■

>.. ^

f. s. f:pnr.4»;IrAt. SIMt\'l,V

AV^ lAT. lin'dllT 1HX:| IT., 1,11

I .«<;

«'Ui:iA(.i;i»us.

i >l

372

FOSSIL OSTREID^ OP XORTII AMERIC/

PI-ATK Llii.

EXOGYIU AQflLA Gol.llllsR. (Pa?o304.)

Figs. 1.2.-npj.er and under viewH; natnral size.

1^ 111

L'. K. UEOLUdllAL BLHVKV

ANSI'AI, IIEIOIIT 1883 n,. I.III

I ,,.

CUKTAOKOUS.

'_' ^i^S^i-VlM'-tii* *

I Hi

, I

374

Ko-ssu, osTH.:,..^.; ,„.• sonru amkrfca.

|;^/

i. n

;

r. H, (.Klil.iK.li Al. M IIM V

.\.>M tl llHI'lll |l■^l I'l.. I.IV

■-,*

CUETACKOLS.

'1
/

!(■

FOSSIL OSTREID^ OF NORTH AMERICA.

' I

I IT

PLATE LV.

KxoGYKA wiNcni:u,i Wliito. (PngoSO?.)
Fig. r-Iuferior vio«- of th., l..w..r valve , „a,„ral nizo.

-La,..ra, vu... of .,... ..„. exa.,,,.,... r.. vi..vs of tUo upper va.vo so. P,a,e

K.vociviiA rAHAsrncA Gal.l,. (Page .W.)
o,-Intorior view of a lower valv; natural si/e.
!.-txtorior v.rw of an uj-por valve. After Gahl,.

F.VO(iVi!A COLUMUKr.r.A Mnek. (PaKe:!04.)
5.G.-TW0 lateral view.s of a lower valve; uatnral size.

I. rt. (.Knl,or;l(AI. hi IH r.V

ANSI'AI. i;i;i'cMir (i-'s:i ri.. \.\

('i;i:iALi:ui •

'r'l

1 I

378

FOSSIL OSTUEin^ OK NORTH AMKKICA.

PLA'IK lA'l.

KxooYiiA cosTATA Say. (I'ago;tOI.)
Fig. 1.— Lateral view of a lower valvo; natural size.

2.-Ext^erior view of an upper valve. For ol her liKures of this species see Plate

KXOOYHA AKIBTINA lioeiiier. (l'aKe:i03. t
;i.-La|eraI view of a large lower valve, ^vilU the beak nnusuallv long; natural

4.— A smaller example, sliowini; the upper valve in i)laco.

5.— Lateral view of the same example.

O,r.-Copie.s of .Say's lignres ot DelpMmda laxa for eompaiison will, /■;. „nelina.

I )

I'. S. (iKni.OfilCAl, HIKVIIV

AXN'i.Ai. ur.i'uiii' \m;i vi,. i.vr

CItlil'ACI.oUS.

'-Mii»ammim^itmit*immsMim^s^ssi^.i ..> .v

I ;

■1

580

FOSSIL OSTRKIU^ OF NORTH AMKRICA.

PLATE LVII.

KxoGViiA cosTAiA Suy. (Page ;i04.)

rio. 1.— Exterior virw of a lower viilve; iialural size.
•-'.—Lateral view oC llie same exaniiile.

I. ». OKOUK.ICAI, K UVEV

ANNIAI. llEroUr 1HH3 CI.. I.VII

1 i!i;iAi 1:111 .-i.

382

FOSSIL ostukida: ok noutii amkuica.

PI.ATIC LViri.

OsTltEA OLAliiiA Jlcek it H.iydcti. (Piig>' :!07.)

Viaa. I,'J— ExtorioraiM ii.t..ri..r vimv. of tho typo specimon ; imturul si.e Af
Meek.
3.4.-Siiiiilar vitnvH of a lower vulvc, fioni Colorado.

fur

I, • c.rAi.iiriii \t. Biiivrv

ANN! Al. llfllMll l""! II I * Ml

(

if.

384

FOSSIL OSTKEID^ OF NOUTll AMERICA.

I'LATK LIX.
OsTni:A GLABitA Mook & llaydeii. (I'.ifro :ii)7.)
FlC.s. 1,L>.— ICxtcrior and intcrioi- vuiws of an upper valve.

:!,I.-Si„ular virus of tlic lower valvo of tlio type specimen of 0.

Wliile.
r..— Upper view of tlie type specimen of O. amialilis Meek.

■. S. (iROI.OCIlAI, SIHVKV

AXNTAI. I.'l.l'oiil IrtB,'! .■!,. I.IX

LAKAMIi;.

3 I]N1-

386

KO.SSII. nSTHKlDiT: or NOKTII A.MEKICA.

I' *" I. I

ri.AlE i,x.

Omrea Gi.AiiHA Miili A Iluydiii. i^PiigeiiOT).

Kios. 1,~'.— Extfiior anil inteiiDi- virws ot'ii Colorado i-xiimple.
^,4.— Similar views of a WyoiiiinjT i.xaiiiplfi.

L'. s. (iF.oi.onicAr. una 'n

ANXI'AI. IirrOIlT lOHa I'l.. i.x

. .i -

^ *1

r.AllAMIK.

! I

■i

i <
\

n^MjimmiBmkm^

J88

I'OSSIL ()STI.'l;ll.,r. or NulMii AMKUIfA.

ri.A] I. i,\i.

Ush:|.:a i,i..M>ii.> .M,,k A \\.>y\,-u. . I'a;;,. :!07. )

I'll-J. 1.- Inll'l-i,,! vi,MV „r,M lower wlUr IVUIU \\'.„Mhv'

ii.:!.-U|.l..Ta„.ll.„.,„lvi,.v,„r,.|,e,,i,„..,.,- th,. ,,«!.■ .,f Nuev., Le.,,, M-ii,

OSIKIIA Mllll;l(i,,.SAi,T< Kv.'lll.- A M, :,|. fp.,^,,. mw )

■l.-K.\lcii„i- ^i,.^v.,l^nl ii|.|i.r v.ihv: ,.,Uiii;,l ni/..-.

• I. — Interior view (ifllii. «^,iiie ex:iMi|>le,

<i.— Kxleriiir view of a lowiT valve.

7.— Inierior view of iiiiotlii'r low. r v;ilve.

)

(' « nliilncHAI. »1 ll\(V

ANSI Al. riH'(.|ll I 1 l-l.. I.XI

-f

I.AltAMIK.

wir^fwr^''

•i'

^,. ..IJ.I1II ^Plilll!

390

FOSSIL OSTlfEIDj: OF NOKTH AMKRICA.

PLATK I,XH.

OsriiKA SKLi„KKOi(Mis Conrad. (PHye 311.1
FlO. 1.— Upper vitfw; imtmalsize.

2.— Lateral view (iftlio.s:iim« exaiiipl.'. For miolher viow si« I'hito XXX.

i '

I . ^. i.lnlAHiliAI. Sl'UVl.V

anntai. itKronT l«sj n.. i.mi

i !

timirlllii

'is^swmmm

I. IM

392

FOSSIL OSTKKIO^ OK NOKTH AMKIilCA.

(

i'l.ATK i.XIII.

OsTUKA sKi.r,.f.Koi,','is, Conrail. (Vh'^. A]).)
Km. 1.— IJiidnr view of tlii> c.x.iriii.lc iliai isli^nrcd ,,ri I'liit,' XXIX.
(.)sTi!t:.\ vicK.sBi-i:fi|-..v.sis, Counnl. < Piijjr- :;i-,', )
•■i, :!.— Kxtcrior nml iiitcn.ir views ot'.-i IniviT viilvp; n,itiii;il si/,i-,

OSTUKA Tiiiim,*; Galili. (Puirpilll.)
4, .'), t).— Kxtenoi, lateral, and interior views of a luwor valvi ; naliiial size.

i;. s. (iKcii.nnicAi. .-ruvrv

VSMAI. lirroiri IKK) [■[.. \.\u\

'■

,4!

IStC»::w^^sr'^^ai!«. — -ia:aK'J"-a^' zsasvuui

.-...JllJ.. JUP.

mmmmmmfi

394

mmmm

FOSSII, c»srKK,Il>,4: OV NfUMII A>[n!I(A

I I

I'l.Aii; I, XIV.

OsrilKA lir\ AMICA I A I,1M. ( l':iLre lUD.'l
l''l(l. 1.— C(ili,\ c>fI.r;l'Mirij;iM.i| |i;;iii,.,

l'Sllli:.\ AI.AHAMKN.-IS l,,;|, ( l'ili;|. Illl'.l. )

Ku). •,',— t'()|i.\ 111' I.cir.s 1.1 iMiiiiil li;4iiii',

;i.— Coii.v ofl.i'ii'M li«iiir (if iIk' I'onii lie ciillrd O. U„ij„u-canil.
4.— (.'Kpy (.n,.M\ liijinv c.f 111.' I'l.nii lir I'.illr.l (I. s,n,i-h(,iata.

(1.SIHIA i:vi:i<sA Mcllvilliv (I'lij... :;I0.)

f>. (1.— KxliTiiii- 1111(1 iiifcridi- views of a lower valve.

7, 8.— Siiiiiliir vii^ws (if an upper valve. Alter DMliaveH.

< >

!■. H. i.ii.icii.ri \i, Mi.'iivi:v

^( :

IMAGE EVALUATION
TEST TARGET (MT-3)

I/..

1.0

I.I

11.25

lilllSi

2.2

a Hi ■

U 11 1.6

— 6"

Photographic

Scimces
Corporation

23 WEST MAIN STREET

WEBSTER, N.Y. 14580

(716) 873-4503

•^

^^^-

-<*.

<«^>^
<<^.*'

1^ t

396

KOS.StL OSrUElD.f: OF UOHIIl AMIiHICA.

^•)

1'I.ATi: l.v.V.
OSiBKA LO.Mri!KSSlI!llSTl!A Say. (TatiM ;;00.)
Kir.H. 1. -i " r|i|,pr jiiul iiMil.T vip«K ,,|- ;, lnn;o oxamplo; iialural size.

11 t

I i

(

■iBiWruy...

' I HU.Jl ' MlUUl.jm

a;.'S

KMasii, ()sll{Klli-t: OK NOKIll AMi:UlCA.

I'l \ 1 1; I. XVI.

'>-iKr,\ lu-rMiii IS ('(.iHiiil. ,1'npe ;)12.)

FlQ. 1.— Uci'tr vie" ; naluiiil (*i/.c.

2.— I'ndiT view- of atiotlKT i^xiiinplf Al'i'-r Conrad.

m 'T

'^•ii¥'~' 'mm ".T

1 «. iiKDI.cillil Al. «rilVKV

A.NM Al. i:l I'nlll Imi:; I'l. l.X\ I

« 1

Aii(Pli;XK

(

•

"'««|!(

'-1

400

ros.sii, u.srin:ii»jo (»!• nouth amkhka,

, I

I'l.Air. I,X\ M.
O.sruKA iAV|iii;iA\.\ (ImIiI,. (I'ii;;!. :;i;t. )
l-'liis I, •.'. -Upiicr iiii'l laiciial \ ii-w.s; imliiriil sizo. AI'IctOuMi.
OsTiiKA I'i:k( i;a.ssa CihujiI. O'iij,''" ^ilH.)
H— Infrrior vimv of a l,.uii' \,'ilvi>. At'lcr Ci.iir.nl.

I. K. Iimni'i.ll A\ »l IIV>\

ASM *l imi'""! I«»' I'l IN* II

;

•f.

• y»

3 INT 26

ir i

i«

402

FOSSIL USTKKID* OK NORTH AMERICA.

ri.ATE I.XVIII.

i>mhi:a >l itiAicAiA ('i>iira(l. (Paf;o :U\\ )

Fig. 1. — I'ppci- viiw ; natiiial k\/.i\

','. :V— Kxli'iior :mil inlriidi- vic\v> ol' an iiiiiU'i valvo.

(>stki:a Airwdoui GaMi. (ra);i's 111,' ami ;tl4.)

4. — Kxtciior view ot' an under valvi-.

5. — Interior view of another nniler valve. Alter Gnbb.

HMMit»«iaiMiM«MtfM«ai«iiMri

L'. fi. Ct^oUKilCAI. MI ;tVFV

ANNfAI. ItKI'OIlT lH8:i IM,. I.WIM

•^

■f^

MKPlKXK.

(

404

KOaSII, OSTRKIDiE OF NORTH AMERICA.

PLATP LXIX.

OsTHBA coNTRACTA Conrwl. (Page 312.)

I'iGS. 1 . y.~Ext.rior mul inferior vicnvs of a large example ; one-third actual diameter.
After Courad.

-4»

f. M. ilKol.ocili .11. KlllVKV

ANMAI. hKl'Oin IWKI I'l.. I.XIX

■ff

'?EK»-5li;--^5*S?T»^£V:^4J>^!«j3^!*S

imr::!".-*^'^:^!^ ■

406

FOSSIL 08TBEID.E OP NOHTH AMKKICA.

PLATK LXX.
Omtiika vklkiiiana Ciiiirnd. (Page UM.)
I'lO. 1.— Kxterlor view of a lower viilvi'. Al'liT Courud.

OSTKKA 8CULPTUHATA Coiirnd. (Page 313.)
a.— Upper view. After Conrad.

C»

I'. • lIKiiUlillrAI. KlIlVKV

ANM'AL lltl'lilir 18X3 I'l.. I. .XX

<»

-•

MIOCEN'U.

408

FOSSIL OSTKEID^i OF NOKTll AMKKICA.

ri-ATE I.XXI.

0.iTI!\-A liiiri!nKOi-.ii ; Rem. Mill Wi;ilili. il'.inf ;il4.)

1-"IG. 1. — Kxti'imr vii'W ci' n lower v;ilvr. Al'trr (ialili.

ItsTKIA VK81'|;KTINA ColllMil. vl'.li:'' iil.'i.)

Flu*. •-', ;!. — I'.xtciinr mill iiitorior virws i\t' m Iowit vnlve.

4. — FsltM'iiii view ot' iin ii|i)iiT v.ilvi'. At'ter Cimiiicl.

«^.

iJll^

I-. s 111:111.111 ir.n. SI iivi:v

AWTM. Ki'i'din l.-.":i n 1 \\i

«i

<=>

I'l.KH KNK.

•^^

410

FOSSIL OSTKKIDii: OF NORTH AJiEKIOA.

PLATE LXXU.

OsrrtKA VKATCiiii (Jiibli. (PukcwIG.)
Flo. 1.— Exterior view of ii lower valve. After fJabh.

OsTliEA CEUKOSKXSIS (KaiiiioiKli) Galili. (Pago :!15.)
2.— Exterior view of an upper valve. After liabb.

OsntKA I.UHIOA Car[ieiiter. (Page31G.)
Figs. ;!, 4. —Exterior and interior views of a lower valvo; natural .size.

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ANNl-AL ItFVOUr 18H;I I'l . I.X.MI

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I'OST-IM.IOCKNK.

412

FOSSIL OSTRKIU^ OK NORTH AMERICA.

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PLATK LXXIII.

Fia. 1 represents »» Anu'ricaii oyntci in a moderntely "fat" cu.litioii. The heart
ot th,8 spee.men, afCr l,ei„g opene,! for ..v.t t,ve„ty.four hours and exposed to .),.
"ir, would still 1>oal leebly if irritated. '

«and «' f;i,.ataorl:e or arteries s-vou oil a. ll.eso poiu.s from the vent, i.ks „u
. Rht nnnele ; hr, braneluo-.-anliao vessels ; l,j, or^^an of liojanus i„ outline ; /,,,, bran-
elnal pores; e, pencardiae nu-nUrane of riKlit sid. thrown baek ; d, eloaea or eloaeal

spare ; rf, „ervons.,.M,n.l.Knreof the right Hide eo,,ne.linK the parl,-to.sp1anchnie ran-
.on ;,j and the snpra«>sopl,a,..aI ganglion ,g ; f, veufal proeess of the bodvmas::
., g,l s; ,e. o„l eavuy he,we,.n the n.antle l.aves; /,, grooved hinge-end of L IWt
u.he, /, l,gau,ent ; .V, adduetor n.nsele; ,„/, n,antle; ,«/', portion of n.antb, adhe-
rent to body-uia,s«; „ (o ,- n.arks ,„e ext,.,! to nlnd, the riuht and left lea,.., of the
mantle are conllueul ; ;,, pall>s ..rlips ;/, outer end of p.dal nu.sole of ri.^ld side • *'
external opennigof the generative and renal organs of the right side ; r, vn.t or an,,. '■
re, ventnclo, .r,a-,.r, cavities iu the edge of the shell llll,.,l wi,l, n„,d ; „. posterior ex^
tromity ol Ihe gills and. jtmetion of Ma. leaves ..r I lie mantle.

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A.V.NLAi. HKriPlir IHSI |.|,, I.XXIM

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I.lviNii osii;i:iii.i:.

414

KOH.SIL OSTBKMiiE OK NoKTII AMKIIKA.

I'l.Aii: i.xxiv,

rid. •.'(I""-,.,). .IH. aMricl..;/,,,,, ImmIv ,„„s,. ; , /, ,1,„„ a; '/, KiH- i i nmU', ii.lrstlne;

Mivrr, will. i(«,lMriH,)i...iiini; into tlir st,, 1, ; .1/, „,|,l,iet,.i-; m.nmnth; ml, mnn-

rloj », plan., ihton^'h whirl, the w.ti,.,, i..|,r,.„.,„..,l i„ V\g. ;; „aH .■,.(,; ;,, oiitrr .•...•-
rii){.ilc(l Niirt'ai'o of iniii'i- w lnwcr palp ; r, vcmiI ; re, vnitrii;!...

Via. M(iipp,.i). S.tiioii llimuKl. th,. plan..»„r li«mo •,>, Ni.s,,,! |Vo„, ,i,r animor
sMl... and .nlai-...! al.oi.t two ,liani,t.rH ; ,.' ami n", .lorsal and ventral Inan.hcs of

fhoanlcnor a..rt.. In Hr.tion ; hr. hianrliial vwl ; ,•, mn tivo tl.sn..; ,/, kIIIs i„

•.•ctM.n; ,/, uifnuil ravili™ of tl„. Kill.; „., la.vn-of K-nriativ.. tisHnror r..p',„,lnclivo
nrdan; ',<, '■■■•ss-M.-llonH of the inf.sllMal tiilir, .showing lh« p..onliar form of tho in-
tmiial cavity; /, livrr or l„|.ali,; ti-..n.,; ml, niantlo; »*, Bnprnbnuichiul or water
iipacos al.ovu tlio kiH"; »I, oiivily of dtoiniich ; it, vtim cava.

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l,l\l\li oM'liKIU.K.

711^^

416

FOSSIL OSTREIDiE OF NORTH AMERICA.

PLATE LXXV.

Fio. 1.— Young American o^-ster, viowid from tUo side immodiatoly after fixation by

tlio mantle border m ; enlarged 183 times.
2.— Four young European oysters taken from the beard of the parent; enlarged

9() times.
3.— Young American oyster, with the lioaks or umbos of the larval shell dovel-

ojicd, and firmly attcched to an old oyster-shell | enlarged IHJ times.
■4.— Young American oyster, attached and beginning to form the spat shell. (The

valves are slightly displaced.) Enlarged OG.tlmes.
5,6.— Very young spat of tlio American oyster, showing the peculiar form of the

true larval shell and that of the spat, and the upwardly directed hinge

border; enlarged X) times.
T.— Lower valve of very young oyster, showirg the great concavity of the larval

valve and the abrupt transition into that of the spat stage; enlarged X>

times.
8.— Older spat viewed from the lower surface after being detached ; enlarged 35

times.
9.— The samespecimeu viewed edgewise, to show the flat lower valveof the spat

and the convex upper one, and the upturned hinge with the larval valves

in place ; enlarged 3o times.

^'- U.— Figures 3, 4, 5, C, 7 and 8 are unfortunately reversed, owing to an oversight
in transferring the original camera Uicida sketches. The peaks of the umbos should
look to the loft instead of to the right in order to bring them into a natural position.
Otherwise these figures are accurate.

L'. S, (iFur.<iii|CAL hllHVKV

ANM'AI, mu-OUT IHSrt I'L. I.XXV

I.IVIXU OSTm.lD.t.

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3 INT '27

418

FOSSIL OSTRKID^ OF NORTH AMKKICA.

PLATE LXXVI.

Fig. 4.-r)iagrain of tlio soft parts of tho American o.vHter, showing tlio extent of the
generutivo organ Gen, and the eourscsof thocflerent dnctsof the Icftsiilo,
tho main duct opening at tlie point oi' below tlio uddnctor mnselo miis; ii,
heart; mt, mantle; i>, palp.s; g, gills,

0.— Twenty days' old spat of the American oyster viewed from above, natural
size.

C— Forty-four days' old spat, natural size.

7.— Forty-eight days' old spat, natural size.

8.— Young spat oyster, seventy-nine d.iys old.

9.— Young spat oyster, eighty-two days old.

10.— Young oyster, 2i to 3 months old, from inside of a wreck at Capo May, New
Jersey.

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livim: osTKKin.f.

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420

F088IL 08TKK-II)A: OK NORTH AMKBIUA.

s^«

PLATK LXXVII.

Fio. 1.— View of tho iuuer face of tlio right valvo of a typical Aiuuricaii oyster,
Kio. y.— View i)f tlio external siirfaco of tho preceding.

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4-22

rossiL osTHKiDit; or noutu amkrica

lM,ATi: Lxxvm.

Vm. 1. \'ic\v cil' ilu' imiir muI'ii'.' oni'c li'l'l or drcpivt valvo lioldiijjiii!; to tlio Kpcci-

iiu'i. ii'iutsiiHimI on I'lalc Ixxvii.
Kio. -J.- \ it'w .il'llii' cNtiTiiiil sml'.icc ofllu' iiit'iTdin^.

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424

FOSSIL OSTRUIDiE OP NORTH AMEUICA.

FIGURE LXXIX.

Figs. 1, 2. — Views of tlio iiisidoand siiloof tlio very ventricose orcuii-like lower valve

ol a short and thick speciiiicu of Ostrra virginica.
Figs. 3, 4. — ViewH of the internal and external surfaces of the flat upper or right

valve of the same specimen.

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ASKiAi. i;i:riii;i l^«:l n . i.wix

l.ivi.Nii <>si im:ii).i.;.

426

FOSSIL OSTUKIDiE 01" NOUTII AMKUICA.

«*^

PLATK I. XXX.

ViiMvH of tlio imu-r anil outer miifiiccs of tlio rit'ht aud left viilv. h of tlio northern form
of tlio Auuriciin ojNlcr, (Mrea horealia, sliowiiig tUo lower valvo Htrougly llnteil.

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428

FOSSIL OSTRKID/K OK NOUTII AMTRirA.

I'LATE LXXXI.

Via. I.— View of inner smt'iui' of Hii> iij;lit valvo of an eloiijjati'd spcciiiion o( Ostna
i-iiv/iiiicii, known as llic racrcon. "coon," or '• cat's Inngiio" oj-Rti-r among oysternicii,
nalnral nIzo.

Pig. o — Holh valves of tho foicnoitij^ Hiii'cinion i)lacc, with i!io outor surface of lhi<
right va)'o facing tlic observer.

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430

I'OSSIL OSTElilUiE OF NORTH AMKKICA.

^'l<

PLATE I.XXXII.

Three views of the right and left valves of a smaller 8i)eoimen of the raccoou or cat's
tongue oyster.

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