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A. AGASSIZ.

HARVARD UNIVERSITY.

LIBRARY

OF THE

MUSEUM

OF GOMPAEATIVE

GIFT OF

ALEX. AGASSIZ.

ZOOLOGY

Mac

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_-JL.'

THE

KAY S 0 C I E T Y.

INSTITUTED MDCCCXLIV.

3^

LONDON

MDCCCLXII.

^^l

-?

INTRODUCTION

TO THE STUDY OF THE

F 0 R A M I N I F E R A

BY

WILLIAM ]]. CARPENTER, M.D., F.R.S., F.L.S.. F.CI.S.,

KEGISTRJE OF THE UNITEKSITY OF LONDON,
ETC.! ETC.

ASSISTED BY

WII.LIAM K. PARKEE, ESQ.,

AND

T. RUPEET JONES, ESQ., E.G.S.

LONDON:

PUBLISHED FOR THE RAY SOCIETY BY
ROBERT HARDWICKE, 193, PICCADILLY.

MDCCCLXII.

MCZ LIBRARY
HARVARD UNIVERSITY
CAMBRIDGE. MA USA

PKINTED BT J. E. ADLARD,
BABTHOLOWEW CLOSE.

P R E E A C E.

When, some years since, I undertook to prepare for the Ray Society an outline view of
the structure, physiology, and systematic arrangement of the Foraminifera generally, I had no
idea of contributing anything else than an introduction to my friend Prof. W. C. Williamson's
' Recent Foraminifera of Great Britain.' With the progress of my own researches, however,
I came more and more strongly to feel how unsatisfactory are the results of the method
pursued by M. D'Orbigny and by those who have followed his lead, both as regards the
multiplication of species, the distinction of genera, and the grouping of these genera into
families and orders. I found, moreover, that notwithstanding the dissimilarity between the
lines of inquiry pursued by myself on the one hand and by my friends Messrs. Parker and
Rupert Jones on the other, they led to conclusions most singularly accordant. My own studies
had been restricted to a hmited range of types (for the most part collected by Mr. Jukes on
the Australian coast and by Mr. Cuming in the Philippine Seas), which included, however, all
the most complex and highly developed forms of recent Foraminifera ; and I had specially de-
voted myself to the elucidation of their structure and physiology, and to the careful comparison
of their numerous varietal forms. Theirs, on the other hand, had involved the comparison of
the zoological characters of vast numbers of representatives of nearly all the generic types
of the group, fossil as well as recent, brought together from various parts of the
world, from various depths in the ocean, and from various geological formations ; but had
not been prosecuted with the same minuteness in regard to the details of internal struc-
ture or to physiological -relations. Yet we had all been alike brought to recognise—

VI PREFACE.

(1) the extreme latitude of the rm>ge of variation in this group, which breaks down in ahnost
every instance the boundaries wliieh it has Ijcen attempted to erect between species ; (2) the
necessity of a hke abolition of the divisions between many reputed genera which have been
erected on an equally insecure basis ; (3) the completely unnatural character of any system
which makes a fundamental division between the INIonothalamous and the Polythalamous
types, and which adopts Plan of Growth (that is, the geometrical arrangement of aggrega-
tions of successive segments) as the basis of the subdivision of the PoJgthalamia into orders; and
(4) the fundamental importance, in the determination of the true affinities of the several
generic types, of all that relates to the physiological condition of the animal, especially the
texture of the shell, and the peculiarities of conformation which characterise its individual
segments.

Not only, moreover, did there prove to be this complete harmony in our general results,
but there was also a singular unity in the aggregate of the work we had respectively accom-
plished, each portion being, so to speak, the complement of the other ; so that, on comparing
notes, we found that we had between us pretty thoroughly investigated the entire group.
Hence I was led to propose to the Council of the Ray Society an enlargement of my original
plan, so as to include the results of my friends' labours, and to render the whole an expression
of our joint views. This I did in the expectation that wo might associate ourselves together
in such a manner that whilst the general plan and a part of the details of its working out
would rest with me, a large share in the execution would be taken by my coadjutors. We
soon found, however, that it would be more conducive both to unity of design and to com-
pleteness of effect for the whole to be wrought out by myself; and it has been by the
necessity which thence arose for my personal study of many types with which I was previously
but little or not at all acquainted, that the delay in the production of the work has for the
most part been occasioned. The materials for this study have been most liberally supplied to
me by Messrs. Parker and Rupert Jones ; and as to many types which they had previously
made the object of special researches (such as the Milioline, Nodosarine, Texfidarine, and
Botali/ie grou\)s'), I have found that I had nothing to do but to accept their well-considered and
satisfactory conclusions. In certain other cases, especially in regard to the genus Bacii/hpora
and to that collection of forms which they had described under the generic designation
Orhitolina (here referred to the genera Tinoporus and Pafellina), my own investigation of the
materials which they have placed in my hands has led me to results in some respects different
from those which they had published ; but as they have seen reason to accept my modifica-
tions, the account of those types here given may be regarded as not less theirs than mine. In
regard to the genus Nummidina, the most important cf all Poraminifera in a geological point of
view, we have found ourselves in complete accordance as to the impossibility of drawing definite
lines of demarcation between its reputed species; my researches on the varietal forms of the
closely related genus Ojjercidina having led me to conclusions as to the variability of all the
differential characters on which reliance had been placed, precisely Qorresponding wdth those at

PREFACE. vii

which Messrs. Parker and Rupert Jones had arrived from a careful comparative study of the
various forms of Numntulina iiroper. I liave endeavoured, as each genus came successively
under review, to specify what share in the special investigation of its characters is due to
my coadjutors, and what has been more particularly my own ; where no such intimation is
given, we may be regarded as jointly responsible.

That our work will prove altogether satisfactory, either to the scientific or to the general
reader, is more than we can venture to anticipate. Those who look for precise definitions
will not find them here, for the simple reason that the conclusion has been forced upon us
\\\?i\,sliarply defined divisions — whether between species, genera, families, or orders — do not e.visf
amonr/ Foraminifera. And we are satisfied that any one whose study of tlie group shall have
been coextensive with our own must be ready to this extent to endorse our results. It has
been our aim, therefore, to set forth (so to speak) the fundamental " idea " of eacli of the
generic types we have adopted, rather than to attempt a precise limitation of its boundaries.
That some of our generic distinctions may be invahdated by more extended research, is just
as likely as that new generic types may present themselves among the collections from ocean
beds yet unexplored, or from geological formations as yet unscrutinised. The whole study
of this group must still be regarded as in its infancy ; and the utmost that we can hope for
this Introduction is, that it may help to give a riijht direction to that 'study. We have the
fullest confidence in the correctness of our general principles ; and shall not shrink from the
consequences of their application to our own work, however large a part of it may thereby be
superseded by something better. I have endeavoured throughout my own scientific career to
keep in view the noble character given by Schiller of the true pliilosopher, as distinguished
from the trader in science, that " he has always loved truth better than his system ; and will
gladly exchange her old and defective form for a new and fairer one." And the readiness
with which my coadjutors have accepted my amendments in the instances already alluded to,
affords the fullest assurance of their thorough participation with me in the desire, not only
that whatever is defective in our joint work may lie supplied, but that what is unsound may
be demolished, since what shall remain really good and true will then afford a firmer basis
for the future labours of otiiers.

The study of the Rhizopod type in general, and of the Foraminifera in particular, has
peculiar features of interest to the Physiologist, the Zoologist, and the Geologist.

If the views which I have expressed as to the nature and relations of their living sub-
stance be correct, that substance does not present any such differentiation as is necessary to
constitute what is commonly understood as " organization," even of the lowest degree and
simplest kind ; so that the Piiysiologist has here a case in which those vital operations which
he is accustomed to see carried on by an elaborate apparatus, are performed without any
special instruments whatever, — a little particle of apparently homogeneous jelly changing itself

viii PREFACE.

into a greater variety of forms than the fabled Proteus, laying hold of its food without
members, swallowing it without a mouth, digesting it without a stomach, appropriating its
nutritious material without absorbent vessels or a circulating system, moving from place to
place without muscles, feeling (if it has any power to do so) without nerves, propagating
itself without genital apparatus, and not only this, but in many instances forming shelly
coverings of a symmetry and complexity not surpassed by those of any testaceous animals.

Again, there are certain peculiarities about the Foramini/era which makes this group
singularly adapted for that kind of comparison, at once minute and comprehensive, amongst
large numbers of individual forms, which should be the basis of all Zoological systematization.
The size of the greater part of these organisms is so small, that many hundreds, thousands, or
even tens of thousands of them, may be contained in a pill-box ; and yet it is usually not too
minute to prevent the practised observer from distinguishing the most important peculiarities
of each individual by a hand-magnifier alone, or from dealing with it separately by a very
simple kind of manipulation. Hence the Systematist can easily select and arrange in series such
of his specimens as display sufficient mutual conformity, whilst he sets apart such as are tran-
sitional or osculant ; and an extensive range of varieties may thus be displayed within so small
a compass, that the most divergent and the connecting forms are all recognisable nearly in
the same glance. I am not acquainted with any other group of natural objects, in which such
ready comparison of great numbers of individuals can be made ; and I am much mistaken
if there be a single specimen of plant or animal, of which the range of variation has been
studied by the collocation and comparison under one survey of so large a number of specimens
as have passed under the review of Prof. Williamson, Messrs. Parker and Rupert Jones, and
myself, in our studies of the types to whicli we have respectively given our principal atten-
tion. The extraordinary diversity thus found to exist among organisms which, from the
intimacy of the relationship evinced in the gradational character of those differences as well
as in the variations observable between the several parts of one and the same organism, must
in all probability have had a common origin, seems to me unmistakeably to indicate that the
wide range of forms which this group contains is more likely to have come into existence as a
result of modifications successively occurring in the course of descent from a small number of
original types, than to have originated in the vast number of distinct creations which on the
ordinary hypothesis would be required to account for it. Hence I cannot but believe that any
systematic arrangement of Foraminifera will be of real value only in so far as its basis is laid
in a thorough knowledge of the nature and extent of those variations which every chief modifi-
cation of this type shows itself so peculiarly disposed to exhibit, and as, in building it up, the
idea of natural affinity is accepted as expressing not only degree of mutual conformity, but
actual relationship arising from community of descent more or less remote. For the occurrence
of endless gradational departures from any types which we may assume as fixed, and of links
of connection between such as present the best-marked differentiations, seems to me to point
unmistakeably to this as the only means of escape from that difficulty of indefinite multiplica-

PREFACE. ix

tion which attends the doctrine of distinct specific creations when applied to a group in which
scarcely any two individuals are alike. The case, in fact, is very analogous to that of the
relationship between the various members of the family of Mankind ; for whilst the historical
evidence of actual change in them is so incomplete, as well as so limited in its range, as to be
quite inadequate of itself to establish their community of descent, yet when that evidence is
considered in its relations to analogous facts drawn from the far greater variations of domesti-
cated animals, and to the manifold gradations by which the extreme types are connected,
physiologists of the highest eminence have felt themselves justified in accepting that commu-
nity as probable. Now the modifications which any single type of Foraminifera must have
undergone, to give origin to the whole series of diversified forms presented by that group, are
not greater in comparison with those of which we have direct evidence, than arc those which
the advocate for the specific unity of the Human Races has no hesitation in assuming as
the probable account of their present divergence.

This view of the case derives great force from the fact, which constitutes the special
feature of interest which this group has for the Geologist, that there is strong reason to
regard a large proportion of the existing Foraminifera as the Jirecf lineal descendants of those
of very ancient geological periods. This doctrine was first advanced by Prof. Ehrenberg
in regard to a considerable number of Cretaceous forms ; and has since been fully confirmed
and extended as regards the Tertiary fauna by the admirable researches of Messrs. Rupert
Jones and Parker on the Rhizopodal Fauna of the Mediterranean, as well as by my own com-
parison of the recent and fossil types of Orbitolites, OrbicuUiia, Alveolina, Ojierculbia, and
Calcarina ; and it has been shown to be applicable also to the Secondary fauna, as far back
as the upper part of the Triassic system, by the remarkable results of the investigations of
ni)'' coadjutors in regard to a well-preserved sample of it.

It can scarcely be questioned that such a continuity of the leading types of Foraminifera,
maintained through so long a series of geological periods, and the recurrence of similar
varietal departures from those types, are results of the facility with which creatures of such
low and indefinite organization adapt themselves to a great diversity of external conditions ;
so that, on the one hand, they pass unharmed through changes in those conditions which are
fatal to beings of higlier structure and more specialized constitution ; wliilst, on the other,
they undergo such modifications under the influence of those changes, as may produce a very
wide departure from the original type. Thus we have found strong reason for regarding
Temperature as exerting a most important influence in favouring not merel}^ increase of size
but specialization of development : all the most complicated and specialized forms at present
known being denizens either of tropical or of sub-tropical seas ; and many of these being-
represented in the seas of colder regions by comparatively insignificant examples, wliicli
there seems adequate reason for regarding as of the same specific types with the tropical
forms, even though deficient in some of their apparently most important features. The depth

b

X PREFACE.

of the sea-bottom seems also to affect the prevalence of particular types, and to modify the
forms under which these present themselves ; so that Messrs. Parker and Rupert Jones feel
themselves able to pronounce approximately as to the depth of water at which a deposit of
fossil Foraminifera may have been formed, by a comparison of its specific and varietal types
with those characterising various depths at the present time. And it is specially worthy of
note, that in the greatest depths of the ocean from which Foraminifera have been brought by
deep-sea soundings, these belong almost exclusively to one type, Glohigerina, one of the most
simple of the Polythalamia.

In applying the results of the foregoing inquiry to the Animal Kingdom generally, it
may be at once conceded that no other group affords anything like the same evidence, on the
one hand of the derivation of a multitude of distinguishable forms from a few primitive
types, and on the other of the continuity of those types through a vast succession of
geological epochs. But a nearly parallel case, as regards the first of these points, is pre-
sented by certain of the humbler groups of the Vegetable Kingdom ; in which it is becoming
more and more apparent, from the careful study of their life-history, not only that their range
of variation is extremely wide, but that a large number of reputed genera and species have
been erected on no better foundation than that afforded by the transitory phases of types
hitherto known only in their states of more advanced development. It would be very un-
reasonable to put aside these cases as so far exceptional, that no inferences founded upon
them can have any application to the higher forms of Animal and Vegetable life. For it is
only in the extent of their range of variation, that Foraminifera and Protojihyta differ from
Vertehrata and PUanerogamia ; and the main principle which must be taken as the basis of
the systematic arrangement of the former groups — that of ascertaining the range of variation
by an extensive comparison of indi\adual forms — is one which finds its application in every
department of Natural History, and is now recognised and acted on by all the most eminent
Botanists, Zoologists, and Palaeontologists.

The following are the general propositions which it appears to me justifiable to base on
the researches of which I have now given a resume :

a'

I. The range of variation is so great among Foraminifera, as to include not merely the
differential characters which systematists proceeding upon the ordinary methods have
accounted specific, but also those upon which the greater part of the genera of this group have
been founded, and even in some instances those of its orders.

II. The ordinary notion of species, as assemblages of individuals marked out from each
other by definite characters that have been genetically transmitted from original proto-
types similarly distinguished, is quite inapplicable to this group ; since even if the limits of
such assemblages were extended so as to include what would elsewhere be accounted genera,

PREFACE. xi

they would still be found so intimately connected by gradational links, that definite lines of
demarcation could not be drawn between them.

III. The only natural classification of the vast aggregate of diversified forms which this
group contains, will be one which ranges them according to their direction and degree of
divergence from a small number of principal family-types ; and any subordinate groupings of
genera and species which may be adopted for the convenience of description and nomencla-
ture, must be regarded merely as assemblages of forms characterised by the nature and
degree of the modifications of the original type, which they may have respectively acquired
in the course of genetic descent from a common ancestry.

IV. Even in regard to these family-types, it may fairly be questioned whether analogical
evidence does not rather favour the idea of their derivation from a common original, than
that of their primitive distinctness.

V. The evidence in regard to the genetic continuity between the Foraminifera of succes-
sive geological periods, and between those of the later of these periods and the existing in-
habitants of our seas, is as complete as the nature of the case admits.

VI. There is no evidence of any fundamental modification or advance in the Forami-
niferous type from the Palaeozoic period to the present time. The most marked transition
appears to have taken place between the Cretaceous period, whose Foraminiferous fauna
seems to have been chiefly composed of the smaller and simpler types, and the commence-
ment of the Tertiary series, of which one of the earliest members was the Nummulitic Lime-
stone, which forms a stratum of enormous thickness that ranges over wide areas in Europe,
Asia, and America, and is chiefly composed of the largest and most specialized forms of the
entire group. But these were not unrepresented in previous epociis ; and their extraordinary
development may have been simply due to the prevalence of conditions that specially favoured
it. The Foraminiferous fauna of our own seas probably presents a greater range of variety
than existed at any preceding period ; but there is no indication of any tendency to eleva-
tion towards a higher type.

VII. The general principles thus educed from the study of the Foraminifera should be
followed in the investigation of the systematic affinities of each of those great types of Animal
and Vegetable form, which is marked out by its physiological distinctness from tlie rest.
In every one of these there is ample evidence of variability ; and the limits of that varia-
bility have to be determined by a far more extended comparison than has been usually
thought necessary, before the real relations of their diS"erent forms can be even approximately
determined.

xu

PREFACE.

VIII. As it is the aim of the Physical Philosopher to determine " what are the fewest
and simplest assumptions, which being granted, the whole existing order of nature would
result,"* so the aim of the Philosophic Naturalist should be to determine how small a
number of primitive types may be reasonably supposed to have given origin by the ordinary
course of "descent with modification " to the vast multitude of diversified forms that have
peopled the globe during the long succession of geological ages, and constitute its present
Fauna and Flora.

* Mill's ' Logic/ 3rd edition, vol. i, p. 327.

TABLE OF CONTE?s'TS.

CHAPTER I.

Historical Summary.

PAGE

First Period .
Second Period

Third Period
Fourth Period

PAGE
I

7
9

CHAPTER II.
Op the Rhizopoda generally; their Organization and Physiological History:

THEIR distribution INTO SUBORDINATE GrOUPS

Order RADIOLARIA
Actinophryna
acanthometrina
polycystina
Thalassicollina

Reproduction of Rhizopoda

. 18

Order LOBOSA

18

Amosbina

. 21

Order RETICULARIA

. 21

Lieberkuhnia .

. 22

Gromia

Foraminifera

12
23

23
28
28
22
30
32

CHAPTER III.
Of THE Foraminifera generally ; their Chief Types of Structure and Modes of Growth,

AND THE PRINCIP:

Texture of the shell
Mode of increase
Intermediate skeleton
Canal-system
Separation of segments

LES TO BE FOLLOWED IN THEIR CLASSIFICATION

. 40

. 44

Plan of growth

. 53

. 48

Septal aperture

. 55

. 50

Form of septal plane .

57

. 50

Surface-marking

. 59

s . .51

General summary

. 61

Of the Sub-Ordf

R Imferforata

. 62

Genus I. Lieberkuhnia

CHAPTER IV.

Of the Family Gromida .

C3 Genus II. Gromia

Genus III. Lar/ynis

65

63
64

CHAPTER V.

Of the Family Miholida .

63

Genus I. Sqamulina

67

Geuus VII. Peneroplis

84

II. Cornuspira

68

VIII. Orhiculina

93

III. Nubemlaria

69

IX. AlveoUna

99

IV. Vertebralina

72

X. Orbitolites

105

V. Miliola .

74

XI. Dacttjlopora

127

Hauerina

81

XII. Acicularia

137

VI. Fabularia.

82

XIV

TABLE OF CONTENTS.

CHAPTER VI.
Of the Family Lituolida.

PAGE

Genus I. Trochammina . . 141 Genus II. Lititola

Genus III. ValvuUna . . . 146

PAGE

143

CHAPTER YH.
Of the Sub-Order Perforata

149

CHAPTER VIII.

Of the Family Lagexida

Genus I. Lagena

. 156

Genus III. Orthoccrina

Entosolenia

. 157

IV. Pohjmorphina

II. Nodosarina

. 159

V. Uvigerina .

Nodosaria

. 161

Cristellaria

. 162

Intermediate forms .

. 163

154

166
166
169

CHAPTER IX.

Genus I. OrbuUna.
II. Ovulites .
III. Sptrillina
Sub-Family GlobigerinjE
Genus IV. Globigerina
\. PuUenia .
VI. Spharoidina
VII. Carpenteria
Sub-Family Textularin^
Genus VIII. Textularia

IX. Chrysadilina
X. Cuneolina

Of the

Fa.mily

Globigerinida

. 171

176

Genus XI. Btdimina

. 194

179

XII. Cassidulina

. 197

180

Sub-Family Rotalin^ .

. 198

181

Genus XIII. Discorbina

. 203

181

XIV. Planorhdinu

. 206

184

XV. PulvinuUna

. 210

185

XVI. Rotalia

. 212

186

XVII. Cynibahpora

. 215

189

XVIII. Calcarina

. 216

189

XIX. Tinoporus

. 223

193

XX. PatcUina

229

193

XXI. Polytrcma

. 235

UF

Genus I. Amphistegina

the tam
. 241

II. Operculina.

. 24.7

III. Nummtdina

. 262

IV. Pohjstomella

. 276

Nonionina

. 286

CHAPTER X.
Of the Family Nummulinida.

Genus V. Heterostegina

VI. Cycloclypeus

"Vll. Orbitoides

IX. Fusulina .

238
288
292
298
304

LIST OF WOOD ENGRAVINGS.

Fig. tage

I. Coccospheres and Coccolitlis . . . . . .47

II. Composite coccospheres with attached coccoliths .... 18

ID. Diagram of Artieidinc Vertebralina . . . . . -1-9

IV. Diagram of a Frondicularian Nodosaria . . . . .49

V. Diagram of the chambered structure of Orb'itolina . . . .50

VI. Diagram of the chambered structivre of Orbitoides . . . .50

VII. Diagrammatic section of simple NautUoid shell . . . .50

VIII. Diagrammatic section of Operculina . . . . .50

IX. Vertical sections of six specimens of Operculina . . . .57

X. Vertical sections of three outer convolutions of Operculina . . .58

XI. Lateral view of Nautiloid shell, with investing convolutions . . .58

XII. Front view of Nautiloid shell, with non-investing convolutions . . .59

XIII. Front view of Nautiloid shell, with investing convolutions . . .59

XrV. Diagram of Animal of Miliola . . . . ■ .77

XV. Ideal transverse sections of Spiroloculina . . . . .77

XVI. Ideal transverse sections of Biloculina . . . . .78

XVII. Ideal transverse sections of Qiiincjueloculina . . . . .78

XVIII. Ideal transverse sections of TrilocuUna . . . . . 7fj

XIX. Section of Peneroplis through the median plane . . . .80

XX. Front views of four- specimens of Peneroplis . . . . .89

XXI. Septal planes and apertures from difterent parts oi' the same specimen oi Dendritina . 90
XXII. Simple type of Alveolina, laid open ..... 100

XXIII. Portion of internal cast of complex type of Alveolina . . . .102

XXIV. Interior of simple type of Orbitolites . . ■ ■ .108
XXV. Diagram of Dactylopora eruca ...... 128

XXVI. Diagram of Dactylopora annulus . . . . ... 129

XXVII. Diagram of Dactylopora digitata . . . . ... 1 '■")

XVI

LIST OF WOOD ENGRAVINGS.

Fig.
XXVIII. Diagram of Dactylopora chjpeina

XXIX. Diagram of Dactylopora reticulata

XXX. Diagram of Dentaline Nodosaria

XXXI. Diagram of Frondicidaria

XXXII. Various forms of RotaUna

XXXIII. Abnormal forms of CaJcarina

XXXIV. Specimens of Philippine variety of Cakarina
XXXV. Specimens of ^Mediterranean variety of Calcarina

XXXVI. Abnormal forms of Calcarina
XXXVII. Stracturc of Patellina lenticularis .
XXXVIII. Structure of Patellina Cooki

XXXIX. Irregular disposition of septa in OpercuUna .

XL. Vertical section of three outer convolutions of OpercuUna
XLI. Section of septa of OpercuUna, showing secondary pores
XLII. Vertical sections of six specimens of OpercuUna
XLIII. Septal planes of four specimens of OpercuUna
XLIV. Front view of septal plane closing-in last chamber of OpercuUna

XLV. Section of Heterosteyina through median plane
XL VI. More enlarged portion of similar section
XL VII. Vertical section of young Heterostegina

PAGE

131
132
162
164
201
217
217
217
222
232
233
253
254
254
255
258
260
289
290
291

BIBLIOGRAPHICAL REFERENCES.

Akcuiac, Vicomte d', et Haime : —

I. Description ties Animaux Fossiles du gioupe NummulUique de I'Inde. Paris, 1853.

AuEiiBACn, Dr. Leopold: —

II. Ueber die Einzelligkeit der Amo^/jeu ; in ' Siebold und Kolliker's Zeitschrift,' Band vii (185(3), p. 3ti5.

Bailey, Prof. J. W. :—
iir. On the Origin of Greensand, and its Formatioa in the Oceans of the Present Epoch ; in ' Quarterly Journal
of Microscopical Science,' vol. v (1857), p. 83.
IV. Observations on a newly discovered Animalcule {Pamphar/us) ; in ' Sdliman's Journal,' 2d series, voK xv
(1853), pp. 341— 347, and 'Quarterly Journal of Microscopical Science,' vol. i (1853), pp. 29;i— 299.

Bakker-Webb, p., and Bertiielot, J. :—
V. Histoirc Naturelle des lies Canaries. Paris, 1835-50, torn, ii, p. 123; Foraminifires par M. D'Orbiguy.

Blainville, H. D. dc : —
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xviii BIBLIOGRAPHICAL REFERENCES.

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XIX

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KoLLiKEK, Prof. Alb. : —
LVi. Das Sonnenthierchcn, Acfinophrt/s sol, bescbrieben ; in Sicbold nnd Kiilliker's ' Zeitschrift,' Band i
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Lego, M. S.:—
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LiNN.EUS, C.iK.: —

LXiii. Systema Naturse, per Regna Tria Naturae secundum Classes, Ordiues, Genera, et Species ; cum
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Macdonald, J. D. : —
LXiv. Observations on the ^licroscopic Examination of Foraminifera obtained in Deep-sea Bottoms at the
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Montagu, George : —
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MoNTFOiiT, Denys de : —
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1802-5.
Lxvii. Conchyliologie Systematique, et Classification Mcthodique des Coquilles. Paris, 1808-10.

MiiLiER, Prof. Johannes : —
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tom. iv (1839), p. 1.
LXXii. Dictiounaire Universelle d'Histoirc Naturelle, tom. v, p. 602, Art. Foramini/ires. Paris, 1844.
LXXIII. Foi-amini/cres Fossiles du Bassin Tertiaire de Vieune. Paris, 1846.

Lxxiv. Cours Elementaire de Paleontologie et de Geologic; Foramini/ires in tom. ii, fascic. i. Paris, 1852.
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new series, vol. vi (1858), pp. 53 — 59.

Parker, W. K., and Jones (see also Jones, T. Rupert) : —
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and Gmelin, vol. iii (1859), p. 474.
Lxxvii. On the Nomenclature of the Foramini/era ; Part II, Walker and Montagu, vol. iv (1859), p. 333.
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(1860), p. 29.
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LXXXa. On the Nomenclature of the Foramini/era; Part VI, AveoUna ; vol. viii, p. 161.
LXXX h. On the Nomenclature of the Foramini/era ; Part VII, Opercidina and Nummidina ; vol. viii, p. 229.

BIBLIOGRAPHICAL REFERENCES. xxi

Lxxxi. Dcsci-iptioii of some Foramiiiit'era iVoiu tlic Coast of Norway; in 'Annals of Natural History,' 2(1 series,
vol. xix (18J7), p. 273.

Pekty, Dr. Max : —
LXXSII. Zur Kenntiiiss kleiiister Lcbensformen in (ler Schweitz. Bern, 1852.

Plancus, Janus : —
Lxxxiii. De Conchis minus notis in Littore Arimiueusi ; Venetia, 1/39 ; 2d edit., Roma, 1"60.

Pritcuard, Andrew: —
Lxxxiv. A History of Infusoria, including the Desmidiaceae and Diatoraaceoe, British and Foreign ; Ith edition,
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Reuss, Aug-Em. : —
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p. 210.
Lxxxvi. Die Foraminiferen und Eiitomostraceen des Kreidemergels von Lemberg ; in ' llaidinger's Katurwiss.

Abhandl.,' Band iv, Wieti, 1850.
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xca. See lxxxviii.
xci. Die Foraminiferen der Westphahschen Krei deform ation ; in ' Sitzungsberichte der kaiserl. Akad. der

Wissensch.' Oct. 20, 1859 ; TTien, 1860.
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der Wissensch.' Bd. xliv; Wien, 1861 ; abstract in 'Annals of Nat. Hist.' 3rdser. vol. viii, p. 190.

Sagra, Bamon de la : —
xcii. Histoire Physique, Politique, ct Naturelle de I'lle de Cuba. Paris, 1839. Foraminifbres par M.
D'Orbigny.

Schneider, Anton : —
xcm. Beitriige zur Naturgescbichte der Infusorien ; in 'Muller's Archiv," 1854, p. 191 ; translated in 'Annals

of Natural History,' 2d series, vol. xiv (1854), p. 321.
xciv. Ueber zwei neue ThalassicoUen von Messina; in ' Muller's Archiv,' 1858, p. 38.

SCHROTER, J. S. : —
xcv. Einleitung in die Konchylien-Kenntniss nach Linne. Halle, 1783-86.

xcvi. Neue Literatur und Beitrage zur Keutniss der Naturgescbichte, sonderlich der Konchylien und der
Steine. Leip:i<j, 1/84-87.

ScHULTZE, Prof. Max. : —
xcvii. Ueber den Organismus der Pohjthalamien {Foraminiferen) nebst Bermerkungen iiber die Uhizopoden im

allgemeinen. Leipziy, 1854.
xcviii. Beobachtungen iiber die Fortpflanzung der Polythalamieu ; in ' Muller's Archiv,' 1856, p. 1G5;
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History,' vol. vii (1861), p. 300.

xxii BIBLIOGRAPHICAL REFERENCES.

SoLDAXi, Am:;. : —
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1780.
CI. Testaccogi'apbia ac Zoophytographia parva et micvoscopica. Siena, 17S9-0f<.

SPEXGtER, Lob. : —
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Verxeuil, Ed. de: —
CIV. On the FnsvKna in the Coal-formation of Ohio ; in ' Silliman's American Jouinal,' 2nd series, vol. ii (181(i),
p. 293.
Walkkr, G. see Boys.

Wallicit, Dr. G. C. :—
CIV a. Notes on the Presence of Animal Life at vast depths in the Ocean; London, ISGl.

cry b. Remarks on some novel Phases of Organic Life, and on the Boring Powers of minute Annelids at great
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(1861), p. .S(iO.

INTRODUCTION TO THE STUDY

FORAMINIFERA.

CHAPTER I.

HISTORICAL SUMMARY.

The group of Animals now generally known under the designation Foraminifera has
only of late received even a small measure of that attention which it is entitled to claim, no
less in virtue of its physiological interest, than on account of its zoological and its geological
importance. It is true that of the minute polythalamous shells of which the group is for the
most part composed, many forms have long been familiar to those Testaceologists who did not
limit their attention to the larger shells of ordinary Mollusks ; but the strong resemblance
which many of them bear to the polythalamous shells of the Nautilm, Ort/ioceras, &c., led to a
general belief that the former belong to animals closely allied in structure to those which pro-
duce the latter. Hence Foraminifera were in the first instance ranked as minute forms oi Nautili;
and although a larger acquaintance with their varied forms, and a more exact appreciation of
the differential characters of these, led to the institution of a considerable number of new
genera for their reception, yet their title to constitute a distinct and peculiar group was not
recognised until the year 1825, when it was pointed out by M. D'Orbigny that, whilst the
larger polythalamous shells have their septa traversed by a continuous tube or siphon, usually
membranous, but sometimes shelly, the chambers of these minuter forms communicate by
s\m^\Q foramina in the septa which divide them — a difference on which he founded his primary
division of the class Cephalopoda into two orders, the Sijjhonifera and the Foraminifera.
Although, as will presently appear, the latter o( these titles was conferred under an entire
misconception of the character of the organisms to which it was applied, yet it has continued
to be that under which they have been since most generally known, none more appropriate
having been yet proposed ; and there can be no doubt that M. D'Orbigny's limitation and
designation of the group has had a most important influence in promoting that more special
study which it has since received, and ofnvhich the results are found to possess an interest and
importance that bear no proportion to the apparent insignificance of the objects which have
^ 1

2 HISTORICAL SUMMARY.

furnished them, but are derived from their bearing on the highest and most recondite
problems of Ph)'siology and of the Pliilosoph}" of Classification.

The history of our knowledge of Foramimfera* may be divided into four periods.

The first inchides all the observations made and published in regard to them, from the
time when they first attracted attention, down to the date when they were grouped together
by D'Orbigny as constituting a distinct type of structure. Among the earlier authors in
whose works notices of them are to be found, it may be well specially to mention Plancus
(lxxxiii), Gualtieri (li), Ledermuller (lxi), Spengler (cii), Gronovius (l), and Schroter
(xcv, xcvi) ; as it was on the figures and descriptions of the first three that Linnaeus founded
the accounts of the fifteen species which he admitted into the twelfth editionf of his ' Systeraa
Naturae' (lxiii), and on those of the last three that Gmelin based the seven additional species
which he added in the edition of the same work (xLViii) published by him in 1788. Nearly
all tliese species, whether straight, curved, or spiral, were ranged under the genus Nautilus ;
one only {Miliola scminulum) of those enumerated by Linnaeus, and another (Z?7Ko/ff nauiiloides)
of those added by Gmelin, having been referred by them to the genus So-pula. It is worthy
of notice that the tendency to variation so strikingly exhibited by the shells of this group w-as
clearly perceived by Linna?us ; who, instead of erecting every well-marked variety into a
separate species (as certain of his followers have done), endeavoured to fi.x upon the most
characteristic variety, and invested it with the appropriate specific name, differentiating
other varieties by some mark, number, or subordinate designation. The descriptions given
by Linnaeus and Gmelin, though sufficient to distinguish the few types to which they apply,
either from each other or from the polythalamous Tcstacea with which they were associated,
would not now serve to distinguish them from the numerous allied forms which have since
become known ; but b\" an examination of the original figures and descriptions given by the
authors from whom those systcmatists derived their information, Messrs. Parker and Rupert
Jones (lxxvi) have succeeded in identifying each of the forms to which they gave specific
designations, and have indicated their characters in accordance with the present state of our
knowledge of the group.

The next important contribution to our knowledge of Foraminifera was made by Messrs.
Boys and Walker, in their work (ix) on the minute shells found in the sand in Sandwich Bay and
its neighbourhood, the descriptions being by Jacob, and the drawings by Walker, from
specimens collected by Boys. An account of this work having been already given in Prof.
Williamson's monograph (ex, Introduction, pp. vi), it will be sufficient here to remark that
(as Messrs. Parker and Rupert Jones have pointed out), amongst the Foraminifera which they

* I have thought it advisahle to limit my historical summary to the most important among the
many coutribntions to our existing knowledge of the group. A far more minute history, iu regard
to NumtnuHtes and their allies, is given hy MM. D'Archiac and Haime in their ' Monographie des
Nummulites' (i). And iu Professor Williamson's 'Recent Foraminifera of Great Britain' (to which
valuable Monograph an excellent Bibliography is appended) special notice is taken of all who have
contributed to our knowledge of this department of the British Fauna.

t " Previous editions," says Professor Williamson, " contained the Polythalamia (' Nautili ')
enumerated by other writers; but in the ninth, Linnscus separates them into species, in the tenth he
gives them specific names, and in the twelfth he attaches to them the synonyms of other authors."

HISTORICAL SUMMARY. 3

enumerated are some fossil types that must have been washed by the action of the sea and
of the streams from the neighbouring tertiary clays and sands, and thus have been mixed with
the recent shells in the mud and sands of the coast. The twenty-two forms which they
characterised as distinct species were for the most part referred by them to the genera
Nautilus and Serjnda ; but it is a curious exemplification of the ignorance then prevailing as
to the true characters of the lower tribes of animals, that Glohigerina bulloides should
actually have been referred by them to the genus Echinus, under the name of E. lohatulus.
All the forms recorded by these authors have been identified by the pains-taking inquiries of
Messrs. Parker and Rupert Jones (lxxvii).

By far tlie most elaborate of all the older contributions to the study of Foraminifera were
contained in the works of Soldani (c, Qi) on the recent and fossil shells of the Mediterranean
and its shores. These works, the product of long-continued and careful research, added very
largely to the knowledge previously existing of the microzoic forms belonging to this group,
of which a vast number (many of them only entitled to rank as varieties) are figured, usually
with such accuracy as to admit of being at once recognised ; but from the Ijinomial nomen-
clature not having been adopted by the author, his materials were not rendered so available
as they might have been to subsequent systematists, and many of the types well figured and
described by him have received a multitude of synonyms at the hands of his successors.

The British Foraminifera soon afterwards underwent a new scrutiny, on the part of a
most able concbologist, Colonel Montagu, who, in his ' Testacea Britannica' and its Supplement
(lxv), enumerated thirty-six species — the chief addition to those of Boys and Walker being
from the Milioline group, several species of which he described under the generic designation
Fermiculum, associating with them under the same designation several species of Lagena and
Entosolenia. It is evident that Montagu was much perplexed by the difliculty of defining
the limits of species in this group ; for in describing his Fermiculum intortum (now known
as one of the varieties of Miliola seminulum) he distinctly states tliat this is so variable in its
formation that without great attention it might be formed into several species. Yet, notwith-
standing the warning he might hence have drawn, he was unable to follow the authors next
to be noticed in their comprehensive grouping of widely divergent varieties ; for when
speaking in his Supplement of the numerous forms of Nautilus [Crist ellaria) calcar delineated
by MM. Fichtel and Moll, he remarks — " If these can be admitted to be the same species, we
may bid defiance to specific definition." The species described by Montagu have all been
identified by Messrs. Parker and Rupert Jones (lxxvii).

Contemporaneously with the first publication of Montagu, a most important treatise by
MM. Fichtel and Moll, specially devoted to the minute Polythalamia (xlv), appeared at
Vienna. This treatise formed but a portion of a much larger work, which would have been
brought out by its authors if they had received sufficient encouragement to do so ; and it
includes only those forms which they ranked under the genus Nautilus. These — unlike the
forms described in the works of Walker and Montagu, which are, for the most part, dwarfed
by their northern habitats — are, generally speaking, large, well-grown specific types, mostly
from the Mediterranean area, but partly also from the Red Sea ; and they are so carefully
described, and so admirably figured, that the work will always remain a valuable standard of
reference in regard to the forms of which it treats. Its authors appear to have been strongly
impressed with the difficulty of defining species in this group, and they revert to the Linnean

4 HISTORICAL SUMMARY.

principle of seizing what appeared to be the most characteristic variety, and distinguishing it
by the specific name, whilst they designate the rest by the addition of Greek letters. In this
manner they differentiated no fewer than twelve varieties of Nautilus {Cristellaria) calcar, five
of Nautilus {Calcarina) Spengleri, five oi Nautilus {Cristellaria) cassis, five oi Nautilus {Nummulina)
lenticularis, three of Nautilus {PeneropHs) planatus. and two of several other species. Still they
were so far trammelled by the notion of the Cephalopodous character of these Polythalamia,
that they did not advance nearly as far in this direction as there now seems good reason for
doing. It was their great merit, however, to have recognised the difficulty which presents
itself whenever large numbers of these forms are brought together, instead of evading it by
selecting their specific types, and then putting aside, as of no account, all which do not con-
form to them, after the manner of certain other systematists. The species described in the
work of Fichtel and Moll have been critically studied with their usual care, and their
present appellations given, by Messrs. Parker and Rupert Jones (lxxviii).

At the same period, Lamarck was engaged in the study of the fossil Foraminifera which
are so abundantly found in the Calcaire Grassier and other Eocene beds of France, especially
in the neighbourhood of Paris. These he described and figured, for the most part, as Cepha-
lopods, but in some instances as Corals, in his series of Memoirs on the Invertebi-ated Animals
found in a fossil state in the vicinity of Paris (LViii); and he subsequently repeated these descrip-
tions and figures in his contribution (lix) to the ' Tableau Encyclopedique et Methodique,' with
others derived from the works of preceding authors, and especially from that of MM. Fichtel
and Moll. In the original edition of his great systematic treatise on Invertebrate animals (lx),
Lamarck repeated his specific descriptions of the foregoing types, with some slight additions,
and he distributed them under generic assemblages, many of which he then first introduced.
Although these new genera were created under a total misapprehension of the true nature of
the group, and were by no means satisfactorily defined, yet many of them (such as Nodosaria,
Cristellaria, Botalia, Nummulites, Polystomella, Orbitolifes, and Orbiculina) were truly natural,
and have been retained in all subsequent classifications. The species enumerated by Lamarck
have been critically examined and identified by Messrs. Parker and Rupert Jones (lxxix).

A very different appreciation of the value of characters was shown by Denys de Montfort,
who introduced into his systematic and illustrated treatise on Conchology (lxvii) descrip-
tions and figures of several of the minute shells now ranked as Foraminifera, stating in his
introduction that he was far from pretending to have given all their genera, but that he
aimed at making some, at least, of their singular forms known to naturalists. To this end he
selected several of the types figured and described by Soldani and by Fichtel and Moll, and
added others from his own collection, distributing the whole according to his own notions.
His delineations of them, however, are of the rudest and most inaccurate character, and his
descriptions are no less erroneous, whilst his systematic arrangement displays the worst form of
the worst school of naturalists, — varieties being erected, not only into species, but even into
genera, upon the slenderest possible basis of difference, and without the least regard to the con-
stancy of the characters assumed for their definition. And thus it has come to pass that out of
about sixty new generic names introduced by De Montfort, only a single one, PeneropHs, has
been adopted by subsequent writers, until I found reason to accept another, Tinoporus, as
having been recognised by him as a distinct generic type, though he entirely misapprehended
its nature. The forms described by De Montfort have been identified and referred to their
proper synonyms by Messrs. Parker and Rupert Jones (lxxx).

HISTORICAL SUMMARY. ^5

It would not be right to pass by the labours of MM. Blainville and Defrance in the
same field. In the articles which they contributed to the ' Dictionnaire des Sciences Natu-
relles ' upon Mollusca and Zoophytes, fossil as well as recent, they gave an account of
several new and important types of Foraminifera, without any correct appreciation, however
of their real nature.

The second period in the history of the group of which we are treating commences
with the presentation to the Academic des Sciences, in 1825, of M. D'Orbigny's systematic
arrangement of the Cephalopoda (lxix), in which he first separated these chambered
shells, under the title of Foraminifera, from the Siphonifera ; still retaining the former,
however, like the latter, as an order of Cephalopods. The entire group of Foraminifera,
as then known to him, consisting of none but multilocular shells, he subdivided into five
orders, according to the geometrical plan on which the segments are successively added.
In the first of these, Stichosiegues, the segments are arranged end to end in a single
line, straight or slightly curved. In the second, Hclicodegues, the segments are in like
manner disposed end to end, but their common axis forms a spiral. In the third, Enal-
lodeyues, the segments are added alternately on the one and on the other side of the
first, along two or even three distinct axes, which may be either straight or curved. In
the fourth, Entomostegues, the segments are arranged on the like alternating plan, but the
double axis forms a spiral, as in the Helicostegues. In the fifth, Agathistegues, the successive
segments cluster one over the other around a central axis, each segment forming half of the
circumference. Each of these orders is subdivided into two families, according as the
growth of the segments is equilateral or inequilateral. And the characters of the genera*
(of which a large number were then first instituted by him) were based in part on the
relation of the segments to one another, but chiefly on the number, form, and situation of the
apertures of the last chamber. To the foregoing orders he subsequently added that of
Monostegues, in which there is but a single chamber, and that of Cgdostegues, in which the
segments are very numerous, and are arranged in concentric circles around that from which
they originate.

No suspicion appears at that time to have crossed the mind of M. D'Orbigny, that the
place of these organisms might be amongst the lowest, instead of among the highest, of the
Invertebrata ; and if his determination of their Molluscous nature was based on any actual
observations of these animals in their living state, it is certain that such observations must
have been of the most superficial character. As his labours have contributed far more than
those of all his predecessors put together, to the extension of our knowledge of the diversified
forms belonging to this group, it was most unfortunate that they should have been com-
menced and carried on under the influence of views regarding the value of characters which
have since been proved to be altogether erroneous.

A correct appreciation of the differences presented by the members of any natural group

* A set of models in plaster of Paris, representing on a large scale the generic and sub-generic
types of these (so-called) microscopic Cephalopods, was issued by M. D'Orbigny about the same time ;
and these have proved very useful in the determination of specimens, whose place in his classification
could not readily be ascertained from his descriptions.

6 HISTORICAL SUMMARY.

can only be based on the careful study of its own plan of organization and of the modifica-
tions wliich this shows itself disposed to undergo ; and cannot be safely deduced by analogy
from the study of any other group, however closely related. Least of all can any analogy
be truly available, which is drawn from one of the highest groups of Invertebrate animals,
and applied to one of the very simplest types of animal structure. Had the inquiries of
M. D'Orbigny been conducted on a more philosophic method, he must have necessarily been
led to the discovery, by the mere comparison of sufficient numbers of individuals, that this
analogy is altogether fallacious, and that the ranjje of variation among Foraminifera is so
much greater than it is in any of the higher tribes of animals, as to render of no account
among the former such differences as in the latter would be of even primary value. But his
practice having been (as I have good authority for stating, and as clearly appears also from
his results) to select, or to cause to be selected, out of any large assemblage of Foraminifera
only the strongly differentiated types, and to leave the intermediate forms altogether out of
view, his dominant misconception was not likely to undergo any modification in the course of
his researches, and we find it still clinging to him even after he had been satisfied that the
true place of this group is among the lowest instead of the highest of the Invertebrate series.
Hence it follows that, notwithstanding the immense value and extent of M. D'Oibigny's
contributions to this department of Zoology, — in the first place by having brought together the
scattered components of the group of Foraminifera, and so differentiated it that it thenceforth
took rank as a special object of zoological and physiological study ; secondly, by having
brought together from all quarters of the globe and from geological deposits of various
periods a vast number of forms previously unknown ; thirdly, by having so far investigated
their characters as to be enabled to group them in generic assemblages, of which a con-
siderable proportion are tolerably natural ; and fourthly, by having furnished a classification
which, although eminently artificial, is still preferable to the chaotic confusion in which they
would have otherwise been left, and which has answered a useful purpose as a provisional
arrangement, — there is scarcely any part of his work which is likely to stand the test of time
and further research. For, as will hereafter appear, a large proportion of his species cannot
be legitimately ranked higher tlian varieties, and many even of his genera must be brought
down to the same level; whilst the basis of his primary and secondary subdivisions of the
group is so unnatural, that it separates under distinct orders not a few types vihich have the
closest mutual affinity, and brings into near approximation others which ought to be no less
widely differentiated. It will be sufficient here to remark that it is now clearly established
that the very same type may develope itself either as a Slichodigue, along a straight or slightly
curved axis, or as a Ilelicoste^ue, along a spiral axis; and that certain of the Cydostegue
order are generically, if not specifically, identical with certain Helicostegues. Some suspicion,
indeed, of the unsoundness of his fundamental assumption that the geometrical plan of hicrease
is a character of primary value, appears to have crossed the mind of M. D'Orbigny ; for he
admits (lxxiii, p. 17) that affinities exist among all the orders, which arise out of a change
in the plan of growth that is liable to occur in many types with the advance of life. This
change he affirms (quite erroneously, as we shall hereafter see) to be always in the direction
of simplification ; — the more complicated or special mode of increase peculiar to the order
giving place to one of a more general character, as where in a Helicosieyuc the spiral extends
itself as a straight line, or in an Enallostegue the alternating arrangement of the segments
gives place to a uniserial direction of increase.

HISTORICAL SUMMARY. 7

The results of M. D'Orbigny's researches on Foraminifera are for the most part recorded
in local Faunas. Thus he furnished to the great work of Ramon de la Saj^ra upon Cuba
(xcii), an important article upon the Foraminifera of that island ; a similar contribution to the
account of the Canary Islands, by MM. Barker-Webb and Berthelot (v) ; and a description
of the Foraminifera of South America to his own travels in that country (lxx). So, in his
' Faune de la Craie blanche de Paris' (lxxi) he described the Foraminifera of that deposit;
and in a subsequent work on the fossil Foraminifera of the Tertiary Basin of Vienna (lxxiii)
he took the opportunity afforded by the extraordinary richness of the collection he thence
obtained thrcutrh Baron Hauer, to give a general conspectus of the entire group as then
known to him, at the same time expressing his entire change of opinion in regard to the nature
of the animal by which the shells of the Foraminifera are formed. His latest views on the
general classification of Foraminifera are contained in his ' Elementary Course of Palseontology
and Geology' (lxxiv), wherein we find a description of all the generic types that occur fossil,
to which the number of such as are only known at the present epoch bears an insignificant
proportion. It is here that we meet for the first time with his order Cychstt'gues, which
includes only four genera ; — Orbifolilcs, previously ranked among corals ; Ci/clolina, instituted
by himself in 18;57, but previously ranked among the lUlicostegues ; with Orbilolina and
'Orbitoides, instituted by himself in 1847, but not previously introduced into his classification.

The iliird period, with which our knowledge of the true nature of the Foraminifera
really commenced, is inagurated by the discovery, first announced by M. Dujardin to the
Academic des Sciences in June, 1835, of the Rhizopod type of structure (xxxiii), which was
followed by the demonstration of the essential identity between the ylmwba and other simple
fresh-water Rhizopods (described by Prof. Ehrenberg among the Polygastric Animalcules) and
the Crisfellaria and similar composite forms of marine Foraminifera which had been previously
ranked among Cephalopod Mollusks (xxxi v). The general results of M. Dujardin's observations
were, that the animal body consists, alike in the naked and in the testaceous Rhizopods, of a
mass o^sarcode, a gelatinous, somewhat granular substance, not enclosed in a distinct membrane,
and capable of extending itself into threads of extreme tenuity ; that there is neither mouth
nor digestive cavity, but that alimentary particles, received into the very substance of the
body, are gradually incorporated with it ; and that both the introduction of these particles
and the movements of locomotion are effected by means of pseudopodial prolongations of the
sarcode, put forth in the testaceous forms through apertures in the shell, and capable, when
retracted again, of coalescing with the general mass. In the case of the composite forms, he con-
sidered the entire animal to be made up of a series of segments which are essentially repetitions
one of another, each possessing an independent vitality of its own (xxxvi). He seems to have
continued for some time, however, in uncertainty as to the extent to which this description of
the animal would be applicable to all the bodies ranked by M. D'Orbigny among the Forami-
nifera ; as we find appended to the names of several of those described by him in the
' Dictionnaire Universelle d'Histoire Naturelle' (as Nonionina, Nummulites, and Rotalia) the
abbreviation 3Ioll. ? as well as Foram.

In the article 'Foraminiferes' cowir\h\xi(ii by M. D'Orbigny in 1844 to the same Dictionary
(lxxit), he altogether abandoned the notion of the Cephalopod affinities of the group (without
giving the least hint that he had ever himself entertained it), and described the structure of

8 HISTORICAL SUMMARY.

the animal in a manner which showed that he accepted M. Dujardin's account of it, though
without tlie least reference to the real discoverer of its Rhizopod character. He assigned to
the group a place among the Radiata of Cuvier, intermediate between the Echinodermata and
the Polypifera, on no other grounds, as it would appear, than a fancied analogy between the
pseudopodia issuing through the pores of the shell and the ambulacral cirrhi of an Asterias,
and between those put forth from the aperture of the last chamber and the oral tentacles of a
Hydra. This account is repeated verbatim in his subsequent work on the ' Fossil Foraminifera
of the Vienna Basin' (lxxiii).

It cannot but seem surprising that, notwithstanding the light thrown upon the
inquiry by M. Dujardin in 1835, Prof. Ehrenberg should in 1838 have announced to the
Berlin Academy his conclusion, professedly based on observations of certain forms of these
animals in their living state, that their true place in the animal kingdom is among the Bryozoa
(xxxix). He described them as possessing a distinct alimentary canal, which extends from
segment to segment ; this, however, instead of being single, as in Nonionina, may (he tells us)
be multiple, as in Geoponus ; so that we must regard each segment of the latter, however
apparently resembling the simple segment of the former, as in reality composed of several
adhering bodies. In one instance (he affirms) he found the mouth surrounded by a plumose
sensory and prehensile apparatus, like that of the Fliistrts and Halcyonella ; but, generall)r
speakmg, he admits that this is altogether wanting, the mouth being a simple aperture. He
saw minute extensile tentacula proceeding from all parts of the sieve-like shell, as described
by Dujardin, and admitted their resemblance to the pseudopodia of Difflitgia, &c. ; but he
remarks, " the rest of their organization, which Dujardin has overlooked, removes them from
the Infusoria quite as far as from a chaotic primitive substance." Besides the alimentary
canal. Prof Ehrenberg described a yellowish-brown granular mass as accompanying and
sometimes surrounding it up to the last of the spirals ; this he considered as an ovary (xl).—
To these views he has lately expressed his continued adhesion (xliv), notwithstanding their
complete inconsistency with the results of all the more recent and trustworthy observations
upon the structure of Foraminifera ; and he has contested those of Prof. Schultze in particular
with an irritation and tenacity difficult to reconcile with the single-minded devotion to truth
which a Naturalist who has rendered such services to science might be expected to manifest.*

Our appreciation of the value of the characters afforded by the form, position, and
multiplication of the apertures of communication between the chambers of the shell, must
obviously differ essentially, according as we suppose these to give passage to an organ of such
fundamental importance as an alimentary canal, or regard them as merely serving for the
connexion of the different segments by stolo?is of sarcode. For variations which in the former
case must be regarded as indicative of such essential differences, both in structure and
function, as would rightly characterise distinct genera or even distinct families, may easily be
admitted on the latter view to be of such comparatively trivial moment as to rank no higher
than specific characters, or perhaps even to be matters of individual difference. As I have
already pointed out, the essential importance of this consideration was altogether disregarded

* The Classification of Foraminifera based by Professor Ehrenberg upon views so erroneous, could
not be expected to replace that whicli was previously in vogue ; and as it is now seldom or never
referred to save as a matter of historical interest, there is no occasion to discuss its demerits in detail.

HISTORICAL SUMMARY. ■»

by M. D'Orbigiiy ; and the influence of his doctrines upon those who interested themselves in
the extension of this department of inquiry was for a long time such, as to prevent any other
progress than that which consisted in the discovery of new forms from time to time, and in
the reference of these to their places in his classification.

It was in the year 1 839 that Prof Ehrenberg announced to the Berlin Academy the remark-
able results which he had obtained from the study of the Chalk formation ; a large proportion
of the material of which he affirmed to consist of the shells, either entire or comminuted, of
Foraminifera ; whilst among the types sufficiently well preserved to admit of being deter-
mined, he showed that as many as ten could be identified with species now existing (xl).

The commencement of that fourth period in which the discovery of M. Dujardin has
received its full recognition, may be regarded as dating from the appearance of two Memoirs
published by Prof. W. C. Williamson (of Manchester) in 1847 and 1848. In the former of
these, which was a Monograph of the genus Lagena (cvi), the important truth was for the first
time formally advanced in regard to this type, that the comparison of a sufficiently large
number of individuals would bring to light such a gradational transition from one supposed
species to another, as to demonstrate that their diS'erences must be accounted as of
individual variation only ; a truth which has since been not only most fully confirmed
by the demonstration of its applicability to the reputed species of every genus of Forami-
nifera that has been worked out with similar completeness, but has been found capable of
extension to many generic and even to some ordinal differences. The latter was a communica-
tion to the Microscopical Society, on the structure of the shell and animal of Polystomdla
crispa (cvii), in which for the first time were given the results of a minute microscopical inves-
tigation of thin transparent sections of the Shells of Foraminifera, and which must conse-
quently be regarded as having furnished the starting-point for all future investigations of a
like kind. Among the facts revealed by this method of research were several that became of
essential value to myself, in the inquiry on whicii I was engaged at the same time in regard
to the structure of Nummulites (xii), and served to confirm the inferences I had deduced
from the other features of that important type, as to its participation in the characters of the
Foraminifera generally. In the course of that inquiry I made the discovery, not only of an
elaborate and previously unsuspected structure in the shell itself, but also of a system of canals,
by which it is traversed, and which seems to have an important function in its nutriti(>n. The
subsequent examination of the minute structure of the shells of numerous recent types by
Prof. Williamson (cvni, cix), Mr. Carter (xvin— xxi), and myself (xiii— xvi), has not only
added greatly to our knowledge of the distribution and purposes of this canal-system, but has
led to a much more correct appreciation than was previously attainable of the value of the
several difi'erential characters presented by the respective types ; and a sound basis has thus
been furnished for a truly natural classification, which cannot, however, be erected otherwise
than provisionally, until the same kind of investigation shall have been carried through a
much wider range of types.

Among the most important of the recent contributions to our knowledge of the organiza-
tion and life-history of the Foraminifera, must unquestionably be ranked the treatise published
by Prof. Max Schultze in 1854 (xcvii). The author has enjoyed the opportunity of studying
several typical forms of the group in their living state, and has most carefully described and

10 HISTORICAL SUMMARY.

most beautifully delineated the remarkable phenomena which they pi'esent. His observations,
which fully confirm and supplement those of M. Dujardin, at present constitute our best
source of knowledge on this part of the subject ; and they have since been extended by further
researches (xcviii,xcix), especially in regard to the Reproductive processes, which still, however,
greatly need elucidation. In his investigations of the structure of the testaceous coverings of
these animals, on the other hand. Prof. Schultze has been less successful, in consequence (as it
would appear) of his want of acquaintance with the best method of preparing thin sections of
them ; and he has consequently fallen into some important errors (such as the denial of the
existence of the canal-system, of which the most perfect demonstration is now afforded by the
examination of the internal casts of these organisms, to be presently noticed), and has failed to
obtain that insight into the real relations of the forms he has studied, which could alone justify
him in proposing a new distribution of the group. Although his Classification is in many
respects an improvement upon that of M. D'Orbigny, yet (as I think I shall hereafter
succeed in showing) it is so far from satisfactory as to leave the way quite open for another
attempt, based upon a more thorough knowledge of the objects to be systematically grouped.
A Classification still more recently proposed by Prof. Bronn (xi) is chiefly founded
upon that of M. D'Orbigny, whilst it adopts certain modifications proposed by Prof Schultze.
It cannot, in my opinion, be regarded as less open to objection than either of the systems for
which it is proposed as a substitute.

An entirely new and most valuable source of information in regard to the organization of
the Foraminifera has recently been afforded by the discovery, first announced by Prof.
Ehrenberg (xLiii) in 1853, that their shells occasionally undergo an infiltration of silicate of
iron, that completely fills, not merely their chambers, but their canal-system, even to its
minutest ramifications ; so that if a shell thus infiltrated should itself undergo decomposition,
a perfect internal cast remains of the original body of the animal, with its extensions through-
out the shell. Of such casts it has been shown by Prof. Ehrenberg that the Green Sands
which present themselves in various geological formations, from the Silurian system upwards,
are in great part composed: and his discovery has thus a twofold value, as, on the one
hand, it places before us far more exact representations of the configuration of the animal body,
and of the connexions of its different parts, than we could obtain even from living specimens
by dissolving away their shells with acid (its several portions being disposed to heap them-
selves together in a mass when they lose the support of the calcareous skeleton) ; whilst it
also enables us to identify with great certainty the types of Foraminifera by which these casts
were originally formed, notwithstanding the entire destruction of their shells. It was soon
afterwards shown by Prof. Bailey (U. S.) that a like process of infiltration is taking place at the
present time over certain parts of the ocean-bottom (iii), and that beautiful internal casts are
obtainable by treating with dilute acid Foraminiferous shells whose cavities have thus filled.
By the application of this method to portions of Mr. Jukes's Australian dredgings, Messrs.
W. K. Parker and T. Rupert Jones have obtained a series of internal casts of most wonderful
beauty and completeness, which I have had the advantage of carefully examining ; and it is
with great satisfaction that I can state that in no instance has this examination afforded any
other result, than that of confirming the conclusions to which I had been previously led by
the study of the shell.

A very different line of inquiry has been recently prosecuted with great success by the

HISTORICAL SUMMARY. 11

same careful and diligent observers— that of the comparison of large numbers of individuals
presenting gradational modifications of the same fundamental types; a method first applied by
Prof. Williamson to La^ena, and afterwards by myself to OrhitoUtes, Orhiculina, Peneroplis,
Opercidina, and Calcarina. The particular results to which they have been thus conducted
will be detailed in their proper place ; at present it will be sufficient to state that they have
been led most fully to accept the views of Prof. Williamson and myself in regard to the wide
range of variation which prevails in the group of Foraminifera generally, and that they have
given to those views a most remarkable development (lxxv — lxxx). The same observers are
engaged upon an extensive comparison of the Foraminiferous Faunas of different localities and
epochs, with a view to elucidate the conditions that determine the prevalence of particular
types. Of this comparison the results already given to the world are replete with interest
(liv, lv, lxxxi).

CHAPTER II.

OF THE RHIZOPODA GENERALLY; THEIR ORGANIZATION AND PHYSIOLOGICAL
HISTORY; AND THEIR DISTRIBUTION INTO SUBORDINATE GROUPS.

1 . Neither the Morphological characters nor the Physiological history of the Foraviinifera,
nor their position in the Animal Kingdom, can be properly understood, without a preliminary
survey of the entire Class of Rhizopoda (of which they constitute by far the most important
section), and an exposition of its most distinctive features as made known by modern
research.

2. The Class of Rhizopoda constitutes, with the Classes of Porifera {Sponges), Infu-
soria, and Gregarinida (to all which it is very intimately related), the Sub-Kingdom which
Zoologists have now agreed to designate by the title PROTOZOA, indicative of the simplicity
of its type of organization, or, as it might be almost said, its deficiency in any definite organi-
zation. In none of its members can any traces be found either of a nervous or of a muscular
system; their digestive apparatus is reduced to its simplest possible condition; of a circulating
system a mere rudiment only can be distinguished ; special organs for respiration and excre-
tion seem altogether wanting ; and although there is reason to believe that true se.xual
products are formed by many of them, yet these develope themselves out of the general
substance of the body, instead of in distinct organs set apart for their evolution. Yet, as will
hereafter appear, these creatures perform all the functions which constitute in their aggregate
the life-history of an Animal. They obtain food either by moving actively in search of it, or
by putting forth prehensile appendages which bring it to them ; they introduce their food
into the interior of their bodies, and subject it to a process of digestion whereby its nutritive
material is extracted from the indigestible residue, which is cast forth by an act of defecation ;
they diffuse this material through the general substance of the body, both by the general
movements of its walls, and by the agency of what seems to be a special contractile organ ;
and they apply it to the augmentation of their own bodies by growth, and to the propagation
of their race by reproductive operations of various kinds.

3. As less differentiation of parts exists among Rhizopoda than in either of the other
classes, and as the beings of which that class is composed may be considered as exhibiting
the distinctive attributes of Animal life in their least specialised condition, its place is obviously
at the bottom of the series. In fact, a state of greater simplification can scarcely be
conceived to exist in any living organism, than that which is presented by the creatures

OF THE RHIZOPODA IN GENERAL. 13

which present the most characteristic types of the group, such, for example, as the
Actinoplirys.

4. The designation of this Class (first conferred by M. Dujardin, xxxiii, in 1835, upon a
portion of the animals now included in it, which he ranked only as a family of Ivfusoria) is
founded upon the power just referred to, which is possessed by all the members of it in a
greater or less degree, of putting forth indefinite extensions of the substance of the body, —
sometimes short, broad, and rounded — sometimes longer, slenderer, and gradually tapering to
a point — sometimes immensely elongated, and narrowed to threads of extreme tenuity, — which
are continually varying both in number, form, and dimensions, and which can be altogether
retracted, so as to become incorporated again with the body-substance. These diverging
processes, termed pseudopodia, are used in some instances merely for the prehension of food ;
in some cases, again, their primary office is to move the body from place to place in search of
aliment ; whilst, in another set of cases, they seem to be subservient to both functions : and
as they bear some resemblance on the one side to the ramifying roots of a tree, on the other
to the feet or locomotive appendages of higher animals, the term Rhizopoda, or "root-footed,"
applied to the class of creatures of which their presence is so distinctive a characteristic, is by
no means unexpressive.

5. The soft and almost homogeneous substance of which the body of these animals is
composed, received from M. Dujardin the designation sarcodc, or rudimentary flesh ; and this
designation may be conveniently used, if it be duly kept in mind that " sarcode " is not a
substance sui generis, but is nothing else than the protoplasm* in which every form of animal
structure has its origin, and from which it is evolved by a process of gradual differentiation.
This substance is composed of an albuminoid base, with oil-particles in a state of very fine
division diffused through it ; it is tenacious, extensible, and contractile ; it is diaphanous,
reflecting light rather more than water but less than oil ; and it is dissolved by alkalies (the
aid of heat being necessary if a weak solution be used), rendered perfectly transparent by
acetic acid, and dyed brown by iodine. In the midst of this substance are usually to be
seen vacuoles, or cavities, containing a thinner fluid, which is often coloured ; these are
extremely variable, both in number and size, and their deficiency in any definite limiting walls
is rendered obvious by their not unfrequent coalescence.f There may generally be observed,
in the bodies of Ithizopods, some differentiation between their central and their peripheral
portion ; the substance of the latter being the more pellucid, consistent, and motile, whilst

* That the " sarcode " of Dujardin is nothing more nor less than animal protoplasm not yet
differentiated into cell-wall and cell-contents — a doctrine which has recently been put forth as new by
Professor Schultze (scix),- — was distinctly stated by the Author iu 1856 (see his Manual entitled 'The
Microscope and its Revelations/ chap. ix).

f These " vacuoles," which commonly form themselves around the particles taken in as food,
were mistaken by Professor Ehrenberg under the influence of his " polygastric " hypothesis, for
multiple stom.ichs, each having its own proper wall, and opening into a common alimentary canal,
■which commences and terminates by a definite orifice. This notion, as will hereafter appear, is alto-
gether ideal, and is utterly inconsistent with the real facts of the case.

14 OF THE RHIZOPODA IN GENERAL.

that of the former contains a much larger proportion of the granules and vacuoles, and seems
less endowed with self-activity, though very easily put into passive motion. This differentia-
tion, which is sometimes scarcely perceptible, in other cases proceeds so far that the coloured,
granular, vacuolated sarcode is surrounded by a perfectly transparent envelope ; and the two
portions thus distinguished may be appropriately designated (after Dr. Strethill Wright) as
the endosarc and the ectosarc.

6. In the cases in which this differentation has proceeded furthest, so that the body of the
Rhizopod bears the strongest resemblance to an ordinary " cell " (as is the case with Amoeba
and its allies (^ 21), a nucleus may be distinctly traced ; in those, on the other hand, in which
the original protoplasmic condition is most completely retained (as seems to be the case with
Gromia, and with the Foraminifera generally), no nucleus can be distinguished. The same
appears to be true of the peculiar contractile vesicle, which may be regarded as a vacuole
with a defined wall ; for this seems to be always present in the " ectosarc " of those Rhizopods
which have that portion of the body most differentiated from the " endosarc," whilst it cannot
be traced in the more homogeneous bodies of such as possess no nucleus. In certain Rhizo-
pods belonging to the former category, the body of each individual contains several nuclei, as
well as several contractile vesicles ; and thus, as Prof. Schultze has pointed out (xcix, pp.
315 — 9), it may be regarded as formed by an aggregation of what would, if still more completely
differentiated, have constituted so many distinct cells. In the highest of these composite
forms (^ 20), indeed, it seems probable that complete cells may be developed in the peri-
pheral portion of the body, whilst its interior retains the condition of homogeneous protoplasm.

7. In a large proportion of Rhizopods the body has the power of forming upon its surface
a firm, testaceous envelope. This, in some instances, appears to be wholly composed of an
organic substance resembling chitine ; but in general it is either siliceous, as in the Folycyslina,
or calcareous, as in the Foramini/era, the mineral constituent in each case being combined
with an organic basis-substance. In certain of the last-named group (^ 60 ) the calcareous
constituent is wanting, and the " test" is composed of foreign particles, so regularly arranged and
cemented together as to give it the shape and general aspect of one formed on the ordinary plan.
The ordinary " tests" of Polycystina and Foraminifera, like the loricce of Diatomacese, must be
regarded as generated by a kind of e.xcretion from the surface of the body ; and although the
elaborate structure of those of the most highly organized Foraminifera might seem, at first
sight, to indicate a less simple origin, yet it will be hereafter shown to be readily explicable
according to that viisw (^ 59). There are Rhizopods, on the other hand, in which the body,
instead of being invested with a sihcified " test," is strengthened by siliceous spicules difi'used
through its substance ; and as there is evidence that in certain cases (^ 18) such spicules are
formed by an excretion-process around pseudopodial prolongations of the sarcode, it is pro-
bable that this is the general fact, more especially as Mr. Bowerbank has shown (viii,p. 282)
tliat the spicules of Sponges have originally a cavity in their interior, which is occupied by
soft animal substance.

8. The subdivision of this Class into Orders seems (in the opinion of the author) to be
most satisfactorily accomplished, by taking as a basis those structural characters which are
most expressive of physiological differences. Such characters are presented in the form,

OF THE RHIZOPODA IN GENERAL. 15

proportions, and general arrangement of the pseudopodial extensions ; for, notwithstanding
their apparently unrestricted polymorphism, it will be found that Rhizopods present three very
distinct types ofpseudopodian conformation, to one or other of whicii they may all be referred,
and that the groups thus formed are eminently natural. How intimately related these diver-
sities are to those fundamental potentialities of each type which find so little structural ex-
pression in this lowest form of animal life, appears from the circumstance that even a particle
of protoplasm detached from the general mass of the body will put forth the pseudopodian
extensions characteristic of its type ; those of the substance forced out by crushino- the " test"
of an Arcella (Plate I, fig. 19), having the broad, lobated form of those of the Amwlja, whilst
those of the substance forced out in like manner by crushing the shell of a Polystomella
(Plate IV, fig. 12) have the delicate, thread-like character of those of the Foraminifera generally.

9. In Actinophrys and its allies (Plate I, figs. 1 — 6), which may be considered as constituting
the central or typical group of Rhizopods, the pseuclopodia are very numerous, and, when fully
extended, are long, slender processes, that gradually taper from base to point, and issue
from the body in a radial direction ; they generally remain distinct when they come into
mutual contact, never undergoing that complete fusion which is common in those of Forami-
nifera; and a slow movement of granules maybe seen to take place along their margin, when
the observation is continued for a sufiBcient length of time under high magnifying powers.
The difi'erentiation between the central and the peripheral portions of the body is such as to
mark out the "endosarc" and the " ectosarc" as, on the whole, distinct from each other,
though no definite line of demarcation can be drawn between them. — With the family
ActinopJiryna, which includes certain forms that possess a firm envelope over a larger or
smaller portion of their surface, there seem to be associated, by their more or less complete
conformity in the foregoing characters, the Acanthometrina, in which the body is supported by
a regular framework of radiating siliceous spicules, the Polycystina, in which it is more or less
completely encased in a siliceous "test," and the Thalassicollina, which, whilst apparently
sometimes simple, are generally composed of aggregations of more or less fully difi"erentiated
cells, supported upon a framework of siliceous spicules. This last family obviously establishes
the transition between the typical Rhizopods and Sponges. The four families now enumerated
seem to constitute an eminently natural order, to which the designation Radiolaria
proposed by Midler,* (lxviii) is very appropriate.

10. In Amwba and its allies, which diverge from the typical Rhizopods in the direction
of Gregarinida and Infusoria (both of which Classes contain forms that are scarcely
distinguishable from it), the pseudopodial expansions are few, short, broad, and rounded (Plate
I, figs. 1.5 — 20), seeming rather like lobate extensions of the body itself, than appendages pro-

* The Rliizopoda Radiolaria of Miiller did uot include the Actinopliryna ; and he separated them
iuto two sub-orders, according as they are Simple or Composite — a di.stinction which does not appear
to the author at, all better founded than that according *to which the Foraminifera are primarilv
divided into Monotlialamous and Pohjtltalamous (see If 52). He is glad to find that the views of
MM. Claparede and Lachmann, on this point, seem to be in accordance with his own ; no notice being
taken, in their classification of Rliizopoda (xxv, p. 434), of the families Spliarozoa and Collospltoercs
established by Miiller for the composite forms of ThalassicolUe.

16 OF THE RHIZOPODA IN GENERAL.

ceedino- from it. They are not put forth equally from any part of the surface, but only from
some particular portion ; and this portion, in some of the testaceous forms, is very narrowly
restricted. They show no tendency to mutual cohesion ; and the smoothness and sharp
definition of tiieir outlines makes it obvious that the surface-layer which they derive from the
" ectosarc " possesses considerable consistence. No movement of granules is to be seen along
their margins ; but the larger pseudopodia receive prolongations from the general cavity of
the body (formed by the vacuolation of the " endosarc"), into which its grantdar liquid contents
freely pass when propelled by the contraction of the " ectosarc." The differentiation between
the " ectosarc'' and the " endosarc" here reaches its maximum ; the former having almost the
solidity of a definite membrane, whilst the particles contained in the latter move so readily
upon one another as to show that its consistence is not even that of a viscous liquid. The
increased tenacity of the " ectosarc" necessarily opposes the free entrance of alimentary
substances through any part of the surface ; and it is pretty certain that in some (at least) of
the Amcebina, possibly in all, there is a special oral aperture. — This group contains
testaceous as well as naked forms, which are all so closely related as to constitute but one
natural order; and for these Rhizopoda the name Lobosa may be suggested, as expressing
the lobe-like character of their pseudopodial extensions.*

11. In i\\Q Foraminifera and their alHes, on the other hand, the characteristic features
of the Rhizopod type are (so to speak) exaggerated. The pseudopodial extensions present no
approach to definiteness, either in shape, size, or number (Plate II, Plate III, figs. 1, 2, 3). Some-
times they appear cylindrical, and sometimes form broad, flat bands ; whilst they are often drawn
into threads of such extreme tenuity as to require a high microscopic power for their discern-
ment; tliey coalesce with each other so readily and completely, that no part of their substance
can be regarded as having more than a viscous consistence; their margins are not defined by
continuous lines, but are broken by the granules irregularly disposed along them, so thai they
appear as if torn ; and these granules, when the animal is in a state of activity, are in con-
tinual movement, passing along the pseudopodia from one extremity to the other, or passing
across the connecting threads from one pseudopodium to another, with considerable rapidity.
In all these particulars they present, as Professor Schultze has pointed out (xcix, p. 314), a
striking analogy to the protoplasmic layer of the interior of certain vegetable cells, such as those
of the hairs of Tradescantia, which exhibit the aspect of an irregular network formed by the
inosculation of threads that spring from the mass immediately surrounding the nucleus, and
very closely resembling that which is formed by the pseudopodial extensions of the body of a
Liehcrkiihnia (Plate II), or a Gromia (Plate III, fig. 2). And as it is along this protoplasmic
network in the interior of the cells of Tradescantia, that the stream of granules moves which
has so long attracted the attention of microscopic observers, there is strong reason to believe
that this movement is due in both instances to the same agency — a sort of peristaltic contrac-

* By MM. Claparede and Laclimann (xxv, p. 43t), the Ammbina and the Actinophryna are
united into one Order, to which they give the name Proteina. The relationship of the latter, how-
ever, to the Acanthometrina, &c., seems to the author so intimate, whilst their differentiation from the
Amcebina appears to him to be so decided, that he cannot hesitate iu the belief that the arrangement
he has here proposed is much the more natural.

OF THE RHIZOPODA IN GENERAL. 17

tion in the threads of protoplasm. The low degree of differentiation in the protoplasmic
substance of these Rhizopods is manifested, not merely in their pseudopodia, but also in the
general mass of their bodies ; for although the external portion is less granular and coloured
than the internal, and is of somewhat firmer consistence, yet there is nothing like a definite
distinction between ectosarc and endosarc, so that the departure from the original homogeneity
of the sarcode is here reduced to its minimum. This low grade of differentiation is marked
also by the absence of the " nucleus" and of the " contractile vesicle," neither of which organs
has been yet detected in any members of this group. By far the larger proportion of the
Rhizopods which agree in these general characters are enclosed in calcareous shells, which
may be either monothalamous or polythalamous ; and such constitute the group of Forami-
nifera. In certain cases, however, the " test" is simply membranous (as in Gromia, Plate III,
fig. 2), or it may even be reduced to the condition of a very transparent film (as in Lieberkuhnia ,
Plate II) ; and such forms are distinguished as Gromida. The physiological condition of all
these beings appears to be so closely accordant, as fully to justify their being combined in a
single Order, to which the name Reticulosa may be given, indicative of the reticulated
character of its pseudopodian extensions. The mode of subdividing this Order will be the
subject of discussion in the next Chapter.

According to the foregoing views, the Rhizopoda may be thus arranged :

RHIZOPODA.

LoBosA. Radiolaria. Reticulosa.

Amabina. Actvnopliryna. Gromida.

/ \ Acanthometrina. Foratiiinifera.

/ \ Folycystina.

Thalassicollina.

INFUSORIA. GREGARINIDA. SPONGIADA.

PROTOPHYTA.

18 OF THE RHIZOPODA IN GENERAL :—RADIOLARIA.

Order RADIOLARIA.

12. Actinophryna.* — Commencing our more detailed consideration of these groups with
the one which may be regarded as the most characteristic type of the entire series, we find a
familiar representative of this in the weW-known Jciinop/uy/s (PI. I, figs. 1 — 4), a not uncommon
inhabitant of collections of fresh water in which aquatic plants are growing, and sometimes
also presenting itself in the sea. The form of its body usually approaches the spherical (fig. 1) ;
but it is liable to modification, on the one hand, from the protrusion of the " contractile
vesicle," v, when turgid, on the other, from the projection either of newly ingested food (fig. 2),
or of particles that are about to be got rid of as indigestible. A still greater departure from
the spherical form is seen when the Jc/i?iop//ri/s is undergoing duplicative subdivision (figs. 3,4).
The average diameter of the body is from l-1300th to l-650th of an inch. From every part
of its surface rndiating pseudopodia e.xtend themselves, usually exceeding in length the diameter
of the body, and tapering gradually from base to apex, but sometimes swelling again at their ex-
tremities into enlargements resembling a pin's head. These pseudopodia, however, vary greatly
both in number and in length ; sometimes they are partially or almost entirely retracted (a
change which may be induced by agitation of the water) ; and they may even disappear
so completely, that the animal cannot be distinguished from an Jniwha until they are
again put forth. The endosarc is distinguished by the presence of granular particles, fre-
quently coloured, which are mostly derived from the matters ingested as food ; and by the
nearer approach of its substance to the consistence of a viscid fluid, as is indicated by the move-
ments of these granules. It also usually contains numerous "vacuoles," some of which are seen
to contain the alimentary matters ingested by the animal, when it is examined soon after feeding.
The ectosarc, on the other hand, is more pellucid and of firmer consistence, though not by
any means attaining to the tenacity of a proper membranous envelope. There is, however,
no definite line of division between the endosarc, and the ectosarc, the one graduating
almost insensibly into the other; but it maybe remarked, that the pseudopodia seem to be
derived from the ectosarc alone, the endosarc not extending itself into them. They
possess, moreover, a degree of consistence which usually prevents them from coalescing when
they come into contact with one another; and whenever such a coalescence does take place, it
is to a much smaller extent than is common among Foraminifera (^^ 32, 33). A circulation of
granules may be seen by attentive observation to take place along the pseudopodia of Acti-
nopliri/s ; but it is far less active than that which constitutes so curious a feature in the life-
history of the Foraminifera (^ 34).

13. Although the existence of a "nucleus" in Jctinoplirj/s has been denied, its presence
(in certain species, at least) must be regarded as a well-established fiict.f It presents itself
as a flattened vesicular body, with a well-defined margin, usually of circular outline, and very

* Ou tbis family, see .xi, xxii, xxiv, xxv, xxvii, xxxvi, xxxvni, lvi, lxxxii, lxxxiv, cii^, cv.
t The term " nucleus " was improperly applied by Kolliker (lvi) to the dark granular sub-
stance which coinmonly occupies the central portion of the body. The existence of a true nucleus was

OF THE RHIZOPODA IN GENERAL :—RADIOLARIA. 19

pellucid ; and its central portion is occupied by an aggregation of granular particles, less
defined at its margin, and less regular in shape. It may be brought into view either by
crushing the body of the animalcule, or by the addition of dilute acetic acid. Its diameter
bears a considerable proportion to that of the entire body, being (according to Stein,)
in A. oculafa almost one-third.

14. The AcHnopliryu seems to have little or no power of moving spontaneously from
place to place; in that respect corresponding with the Foraminifera, but differing (as we shall
see) from Amoeba ; and it obtains its food entirely through the instrumentality of its pseudo-
podia, which, by their peculiar adhesive property, attach themselves to bodies that come into
contact with them. Not only motionless particles of Vegetable matter, but actively-moving
Infusoria, Hotifera, and even small Entoiiiostraca are thus entrapped. When the prey is large
and vigorous enough to struggle to escape from its entanglement, it may usually be observed
that the neighbouring pseudopodia bend over and apply themselves to the captive body, so as
to assist in retaining it, and tliat it is slowly drawn by their joint retraction towards the body
of the Adiiwphrys. In other cases, however, the captive seems as if it were paralysed by the
contact of the pseudopodium, remaining motionless for some seconds, and then, without any
visible movement of its captor, gliding either slowly or rapidly in a centripetal direction
along the margin of the pseudopodium to which it adheres, until it becomes jammed, as it
were, between the base of this and of a neighbouring one. It is usually, in fact, by thus
gliding along the margin of the pseudopodium, as if propelled by an invisible peristaltic con-
traction of its sarcode, rather than by a visible retraction of the pseudopodium, that any
small body not capable of offering active resistance is conveyed to its base. Now and then
it seems as if the appetite of the Aciinnplmjs were sated, or the prey not approved of; for
after a few seconds the movements of the latter feebly recommence, and it glides off the
pseudopodium without any effort on the part of the Adinophrys to retain it. When, on the
other hand, the captive is to be used as food, it becomes invested by an expansion of the pro-
toplasmic substance which the body of the Adinophrys sends forth on either side of that of the
captive, so as to meet and inclose it ; and thus a marked prominence is formed (fig. 2), which
gradually subsides as the food is drawn more completely into the interior. There can be no
doubt whatever that aliment may bo thus ingested at any part of the surface, a new mouth,
so to speak, being extemporized whenever and wherever there is occasion for it. The
struggles of the larger animals, and the ciliary action of Hotifera and Infusoria, may some-
times be observed to continue even after they have been thus received into the body; but
these movements at last cease, and the process of digestion then begins. The body taken-in
as food is received into one of the "vacuoles" of the endosarc, where it lies in the first
instance surrounded by liquid ; and its alimentary portion is gradually converted into an
undistinguishable gelatinous mass, which becomes incorporated with the parenchyma, as
may be seen by the general diffusion of any colouring particles it may contain. Several
vacuoles may be occupied at one time by alimentary morsels ; frequently from four to eight
are seen thus filled, and occasionally ten or twelve. Ehrenberg in one instance counted as

denied by Claparecle in liis earlier memoir upon Adinophrys (xxiv) ; but he has since admitted its
presence, at least in A. Eichornii (xxv, p. 419).

20 OF THE RHIZOPODA IN GENERAL :—RADIOLARIA.

many as sixteen. Whilst the digestive process, which usually occupies some hours, is going
on, a sort of slow circulation takes place in the entire mass of the endosarc, with its in-
cluded vacuoles. If, as often happens, the body taken-in as food possesses some hard
indigestible portion (as the shell of an Entomostracan, or the lorica of a Rotifer), this,
after the digestion of the soft parts, is gradually pushed towards the surface, and at last
escapes by an anal opening in the ectosarc, which extemporises itself for the occasion.
Sometimes it may be seen to glide along a pseudopodiiim from its base towards its apex,
after the manner of an animalcule captured as food, but in a reverse direction.

«

15. When an Adbiophri/s is carefully observed for some little time, a rounded promi-
nence is seen to rise slowly and gradually from a particular point on its surface (fig. 1, a),
sometimes increasing until it attains in small individuals nearly one-third of the bulk of the
entire body, but generally stopping at about one-eighth or one-tenth. The substance of this
prominence is so extremely pellucid that it looks almost like a soap-bubble ; and its margin
is so well defined as to be more clearly distinguishable than that of the body generally.
When it has attained its full size, it suddenly contracts and disappears entirely, so that a
flattening of the outline is often observable at the point previously occupied by this remarkable
elevation ; the margin soon becomes rounded 'again, and gradually rises anew into a projec-
tion, which attains its previous highest development, and then suddenly disappears as before.
This alternation of quick contraction and slow dilatation, which maybe seen to go on with
great regularity for many hours continuously, obviously marks this body to be a "contractile
vesicle," analogous to that of Infusoria ; and it is probable that (as may be clearly made out
in certain forms of that group) the fluid propelled by its contractions is transmitted through
channels in the protoplasma, some of which it distends into " vacuoles," whose contents^
by a slow contraction of the substance in which they are excavated, are subsequently
propelled back into the contractile vesicle. Sometimes the " vacuoles " approach the surface
very closely, and may even form projections from it, so that they have been supposed to be
multiple contractile vesicles. The true contractile vesicle, however, is distinguished by the
constancy of its position, by its sharper outline, and by the rhythmical regularity of its alter-
nating contractions and dilatations.

16. Of the reproduction of Adinophrys so little is at present certainly known, that it will
be preferable to bring the observations which have been made upon it into connection with the
similarly incomplete fragments of this portion of their life-history, which have been attained
by the study of other types of Rhizopod structure (1^ 41, 43).

17. The several genera that rank with Adinnplnys in the family Actinophryna present
its fundamental type of structure under various special modifications. Tiius in Tridiodiscus
the body has the form of a flattened spheroid, and the pseudopodia do not radiate from all
parts of its surface, but form a sort of zone round its equatorial region only. In PlayiopUrys,
again, the origin of the pseudopodia is still more limited, for they all pass off in a bundle from
one and the same part of the body ; and this restriction seems to be related to the investment
of the body at other parts by a definite limiting membrane, which is still, however, very
flexible. In P. cylindrica (Plate I, fig. 6), the body is elongated in form, and the pseudopodia issue

OF THE RHIZOPODA IN GENERAL :—RAmOLARIA. 21

forth from one extremity, which is destitute of any membranous envelope; thus affording a
transition towards such genera as Eughjplia (fig. 5), in which the body is inclosed in a flask-
shaped membranous " test," often elegantly sculptured on its surface, and having a wide
orifice from which the pseudopodia are put forth.

18. ACANTHOMETRINA.* — The siliccous skeletons of the Acatliomeirina, which are all
marine, t consist of a number of elongated spines, which meet in a common centre, and
radiate from this with great regularity (PI. I, fig. 7). These spines arc hollow, and the canal
by which each is traversed opens-out near its base into a furrow, by which a pseudopodian
process of the body of the animal gains access to its interior, to issue forth again at its apex.
There are, however, many pseudopodia not thus inclosed, which strongly resemble those of
Actinophnjs in their appearance and their action. The body is spherical in form, and occu-
pies the spaces left between the bases of the spines, which in some species widen-out so
much as to join each other by their edges at some distance from the centre (fig. 8), thus
dividing the interior of the sphere of sarcode into pyramidal segments. The ectosarc seems
to have a more definitely-membranous consistence than in Aclinoplirys ; but it is pierced bv
the pseudopodia, whose convergence may be traced from without inwards, after passing
through it, and it is itself enveloped in a layer of less tenacious protoplasm resembling that
of which the pseudopodia are composed. The cndosarc contains a number of yellow cell-like
globules, resembling those of Thalassicollm, having a thick peripheral layer and a central
cavity. These are rendered brown by tincture of iodine, and are blackened by the sub-
sequent action of sulphuric acid, whilst the rest of the body assumes a deep yellow colour;
on the other hand, they are turned green by hydrochloric acid.

19. PoLYCYSTiN.\.t — The very numerous group of Pohjcystina, whose skeletons furnish
to the microscopist so many objects of the highest interest for their varied beauty, is also
entirely marine ;§ and is distinguished from the foregoing in having the body itself more or
less completely inclosed in a siliceous envelope, fenestrated or perforated witii numerous

* On tins family, see especially xi, xxv, lxviii.

f The Acanthometra echinoides is described by MM. Claparede and Lachin.inn (sxv, p. 460)
as extremely common on some parts of the cuast of Norway; being brought in abundance by westerly
winds into the fiord of Bergen, from which it disappears when the wind changes; but being always
to be found at Glesnaitholm, which is nearer the open sea. To the naked eye, it presents itself as a
crimson-red point, the diameter of its body (not including the spicules or pseudopodia) being
0'15 roillira., or 0-006 inch. This colour is seen under the microscope to depend upon the pre-
sence, in the central part of the body, of a mass of pigment, which, when viewed by transmitted light,
is no longer crimson, but reddish purple. Acanthomelrie do not seem to have yet been discovered near
our own shores. As they are undoubtedly inhabitants of the North Sea, they should be looked-for on
our eastern coast when the wind blows towards the shore.

I On this family, see especially xi, xxv, xli, xlii, lxviii.

§ They are best known as the " Fossil Infusoria of Barbadoes ;" a large proportion of a Sandstone
that prevails through an extensive district of that island, being composed of the siliceous skeletons
of Polycystina, more or less firmly united together by a calcareous cement.

22 OF THE RHIZOPODA IN GENERAL —RADIOLAUIA.

apertures for the passage of pseudopodia, and often furnished with radiating elongations (fig. 9).
The sarcode body is altogether of an ohve-brown colour, but contains yellow globules, like
those of AcanthometrcB. It does not always entirely fill the shell, especially when this does
not form a complete casing ; as in the Euci/rtidium, only the upper part of whose bell-shaped
" test" is occupied by the body, which is divided into four equal lobes. The pseudopodia of
the Polycystina bear a close resemblance to those of Actinoplirys, alike in their gradually
tapering form, their isolation from each other, their radiating direction, their indisposition to
fusion, and the slow movement of granules along their borders.

20. Thalassicollina.* — Certain forms oiFolycystina, in which the fenestrations of the
siliceous shell are so large and in such close proximity that the solid portion constitutes
nothing more than an open network (as is the case with the Didyosoma of Miiller), serve to
connect that group with the ThalassicoHina. Of these bodies, which are found passively
floating on or near the surface of the ocean, very few forms are yet known, and they are
distinguished by Prof. Miiller into the simple and the composite. Of the former we may take
as an illustration his Thalassicollamorum (PI. I, fig. 12), which seems very closely to resemble an
Adinophry.'i, but presents on its surface, partly imbedded in its ectosarc, a number of composite
siliceous spicules (fig. 13), much resembling those of some species of Tethya. In the Th. nudeata
of Huxley, the dark spheroidal body is described by him as surrounded by a transparent gela-
tinous investment, resembling that which incloses the cells of many Protophytes. The former
consists of a spherical vesicle, 1-G5th of an inch in diameter, the wall of which is formed I)v a
strong, resisting, and elastic membrane, whilst the interior is composed of fluid, holding
in suspension granules of various sizes, with a pale, delicate, nuclear body. In the gelatinous
investment many vacuoles are observable, varying in size from l-62d to l-2500th of an inch,
the smallest being innermost ; and scattered among the vacuoles of the inner portion, imme-
diately surrounding the vesicular body, are many yellow, bright spheres (cells?), about
1-1 600th of an inch in diameter, with a multitude of minute granules. From the surface of
the vesicular body delicate branching fibrils are seen to radiate through the gelatinous
envelope, passing between the vacuoles ; and these are beset with excessively minute dark
granules, which are continually circulating among the fibres, but without any definite direc-
tion. In the complex type, which is represented by the Thalassicolla pundata of Huxley (the
Spharozoum 2}undatum of Miiller), the aggregate mass — which may be either spherical,
spheroidal, or hour-glass shaped — is composed of a number of spheroidal bodies, nearly allied
to the preceding, imbedded (like the cells of a Palmdia) in a common gelatinous investment
(fig. 10). Each spheroid is a cell of from l-200lh to l-250th of an inch in diameter,
having a thin but dense membranous wall, and containing a distinct nucleus surrounded by
a mass of granules (fig. 11); and it is surrounded by a zone of siliceous spicules, each con-
sisting of a short cylinder, from either end of which radiate three or four pointed spines, them-
selves beset with pointed processes, closely resembling the spicules of TlaUdtondria. Round
each of these spheroidal vesicles, moreover, is seen an aggregation of the before-mentioned
small bright yellow spheres ; which are also diffused, though more sparingl)', through the
substance of the common gelatinous investment. And through that substance also there are

* On this family, see especially xi, xxv, lii, lxviii, xciv.

OF THE RHIZOPODA IN GENERAL:— LOBOSvV. 23

seen to extend themselves from the surface of each vesicle (fig. 10) radiating fibres, resembling
those of the simple TlialassicoUa niichata. The central part of the mass is hollowed out by
numcrois vacuoles of considerable size, closely pressed together ; and these sometimes coalesce
into a single cavity, so that the aggregate body (which sometimes attains the diameter of an
inch) is in the condition of a hollow sphere. In another form of the same group, distinguished
by Midler as Collosphcpra Huxlaji, the aggregate body (which seems to correspond in all
essential particulars with the preceding) is included within a clear, transparent, brittle, siliceous
envelope, fenestrated by numerous rounded apertures (fig. 14). In this type (which seems to
approximate to the Fohjcystina) there are no spicules, but each spheroidal vesicle contains a
few prismatic crystals.

Order LOBOSA.

21. Amcebin A.*— Returning now to our starting-point — the most generalized type of
Rhizopods — we find in the Amwha and its allies (some of which are inhabitants of almost
every pond that is tenanted by aquatic plants, whilst others ai'e marine) a condition wliich, as
in some respects transitional towards the Infusoria, has caused Prof. Miiller to distinguish them
as " Infusorial Rhizopods." The body of the Amaha, which may vary in diameter from
l-2800th to I-70th of an inch, cannot be said to possess any definite shape, its outline being
determined by the form and number of its pseudopodian prolongations, which are processes
of the body itself, into which the endosarc often passes as well as the ectosarc, and not merely
extensions of the latter, as in Actinopkrijs. Both in form and number these arc continually
undergoing change ; sometimes they are all retracted, so that the shape of the body is simply
spheroidal (PI. I, figs. 16, 17, a); sometimes it puts forth a few broad, short, lobated expansions
(fig. IG, B, c) ; sometimes these are more numerous, slender, and elongated, assuming a radial
direction (fig. 15, A, B, c, d) ; and occasionally they are so greatly multiplied, radiate with
such regularity, and taper so uniformly from base to apex, as strongly to resemble the pseudo-
podia of Adiiiophri/s (fig. 18). The varieties thus presented have been designated under
different specific names ; but, as MM. Claparede and Lachmann have justly observed, the
grounds of such distinction will appear far from sufficient, when the vemiix\ii&)\e poIi/morpJdsm
characteristic of this type has been duly allowed for.

22. The distinction between the endosarc and the ectosarc is far more clearly
marked in Amoeba than in Adinophrys -, the former being much more fluid, whilst the consistence
of the latter is much firmer. It is through the endosarc alone that those coloured and
granular particles are diffused, on which the hue and opacity of the body depend ; the
ectosarc, which forms a layer of greater or less thickness around it, being perfectly pellucid.
The surface layer of the ectosarc in some forms oi Amoeba (as A. bilimbosa) seems almost to
attain a membranous consistence, a distinct double contour being visible all round the body
when at rest (fig. 17, a). Still, it cannot be said that even in such cases the body is

* On this family, see especially ii, xi, xxii, xxiii, xxv, .xxvir, xxxiii, xxxvi, xxxviii,

LXXXII, LXXXIV, XCIII, XCVII.

24 OF THE RHIZOPODA IN GENERAL:— LOBOSA.

inclosed in a proper membranous envelope ; for this investment seems ready to yield at any
point, so as to give exit to the pseudopodial projections put forth by the softer contractile
ectosarc (fig. 17, b). And in ordinary Amoebce, which have no double contour line (figs. 15,
16), it seems most likely that alimentary and other substances can be introduced through
any part of the ectosarc into the interior, as in AdinopJtrt/s, and that indigestible bodies
can be extruded in like manner, though previously to their escape they may often be seen
to push the ectosarc before them, so as to form considerable projections from the surface of
the body. The central portion of the endosarc seems to have an almost aqueous consistence,
the granular particles diffused through it (which are, for the most part, derived directly from
without) being seen to move very freely upon one another with every change in the shape of
the body. There is not, however, a definite limitation between the wall and the contents of
this cavity ; for the peripheral portion of the endosarc is much more tenacious than the
central, and seems to graduate insensibly into the firmer substance of the ectosarc. In the
typical forms of Amoeba (as A. prhiceps, fig. 16, and A. radiosa, fig. 15), the endosarc
passes into the interior of the pseudopodial extensions. But in A. bilimbosa (fig. 17) and
some otiier forms, in which the differentiation of the endosarc and the ectosarc is unusually
great, these extensions are derived from the latter only. In A. porrecta (fig. 18), on the other
hand, the differentiation is far less complete, and the pseudopodia seem to be as much
formed by tlie endosarc as by the ectosarc; in this and other particulars presenting a link of
transition to the shell-less Reticulosa.

23. A "nucleus" [n, figs. 15, c, 17, a) is always distinctly visible in Amoeba, having,
when most perfectly seen, the aspect of a clear, flattened vesicle surrounding a solid and
usually spherical nucleolus; it is adherent to the inner portion of the ectosarc, and projects
from it into the general cavity. — A " contractile vesicle " seems also to be uniformly present ;
though it does not usually make itself so obvious by its external prominence as it
does in Aclinopltri/s.

24. The more advanced differentiation of the central and peripheral portions of the pro-
toplasmic body of Amoeba is made evident by the effects of reagents. If an A. radiosa
(fig. 15) be treated with a dilute alkaline solution, the granular and molecular endosarc
shrinks together and retreats towards the centre, leaving the radiating extensions
of the ectosarc in the condition of cscal tubes, of which the walls are not soluble, at the
ordinary temperature, either in acetic or mineral acids, or in dilute alkaline solutions, thus
agreeing with the envelope noticed by Cohn as possessed by Paramecium and other ciliated
Infusoria, and with the membrane of ordinary animal cells. The nucleus and nucleolus are
readily soluble in alkalies, whilst they are rendered darker and more distinct by dilute acetic
or sulphuric acid, in consequence of the precipitation of a finely granular substance in the
clear vesicular space that surrounds the nucleolus. When treated with more concentrated
acids, the nucleus and nucleolus first expand and then dissolve.

25. The Amoeba and its allies are distinguished in a very marked manner from all other
Rhizopods by the comparative activity of their locomotion ; instead of remaining fixed to one
spot (except when made to change their place by external agency), and entrapping their food

OF THE RHIZOPODA IN GENERAL :—LOBOSA. 25

by their elongated radiating pseudopodia, tliey are continually moving over the field of the
microscope, and receiving into their bodies any small substances which they may happen to
encounter in their progress. This movement is effected by the protrusion of some part of
the periphery of the body into a pseudopodian process of greater or less elongation : towards
this process, and usually for some way into it, there is a current of the internal granular
substance; at the same time there is a retraction of any processes of the like nature which
might have been previously put forth from the other side of the body, and a reflux of the
granular substance from these towards the centre ; and by a continuance of this change)
the entire Ijody is gradually advanced in the direction of the new extension. The kind
of motion thus executed by an Amaeha is described by most observers as a " rolling" action,
this being certainly the aspect whicii it commonly seems to present ; but it is maintained by
MM. Claparede and Lachmann, as the result of a very careful observation of certain forms
of Amceba that present peculiarities in the disposition of their parts which render them (so to
speak) "test objects" as to this point (such as the A. quadrilineata of Carter, and the A. Umax
of Auerbach), that the appearance of rolling is an optical illusion, for that the nucleus and
contractile vesicle always maintain the same position relatively to the rest of the body, and that
" creeping" or rejjfafion would be a more true description of their mode of movement. On
this view, these animals have their ventral surface constantly differentiated from their dorsal,
it being from the former alone that the pseudopodian extensions proceed ; and thus a tran-
sition would seem to be indicated towards the testaceous Ammhinm, in which the dorsal
surface is invested by a shell, and the pseudopodia are strictly limited to the ventral.

26. When the body of an AiiifEha, or one of its extensions, comes into contact with any
small particle, the movement of the former very commonly presses it against the latter with
sufficient force to cause it to make its way through the ectosarc into the cavity of the
endosarc ;* and thus tlie latter may often be seen to contain Diatomacca, Desmidiacece , frag-
ments of larger Algm, Infusoria, Boti/era, and even Entomostraca, with an occasional
intermixture of inorganic particles. These undergo a kind of circulation in the general
cavity of the interior, which is maintained, as just shown, by the movements of the sur-
rounding contractile substance; and tliis circulation (like the movement of the contents of
the stomach in higher animals) doubtless promotes the digestive process. The larger masses
that are available for nutriment are gradually broken up into finer particles ; and these seem
to constitute the granules which are always to be seen diffused in greater or less abundance
through the liquid interior of the endosarc, the colour of those granules being pretty
obviously the same as that of the matters ingested, and the effects of chemical reagents upon
them being identical. Insoluble bodies appear to be rejected from time to time, by making
their way towards the surface, and then penetrating the ectosarc at the point which happens
to be nearest, just as they are in Adinophrys.

* Whilst admitting that there is uo evidence of the existence of a constant definite oral aperture
iu Ammha, MM. Claparede and Lachmann tliink it conceivable that there may be such an aperture,
of which the lips might be exactly applied to one another, as in Amphileptus, so as only to open at the
moment of deglutition. They express themselves as certain, that in their Podostoma filigerum (^ 28)
such a definite oral aperture exists (xxv, p. 418).

4

26 OF THE RHIZOPODA IN GENERAL :— LOEOSA.

27. Th-e "cohtractile vesicle" does not usually project much from the surface ; though in a
form of ^?K<E^« allied to A.princeps, in which it has been carefully studied by MM. Clapar^de
and Lachmann (xxv, p. 427), it bore a very close resemblance, when in its state of greatest
turgescence, to that of Adino'phrys sol. When fully contracted, it disappeared entirely, but
soon presented itself anew as a minute vesicle in the substance of the ectosarc, which enlarged
little by little until it acquired its original dimensions. On its contraction, from four to eight
vacuoles were seen to project on different parts of the body, often at a considerable distance
from the contractile vesicle ;* and when these had attained a certain dimension they seemed
to put themselves in motion towards it, and to discharge their contents into it, — an operation
which is probably performed by a sort of peristaltic movement along a system of canals
excavated in the sarcode-substance, portions of which are distended into larger cavities by the
contractions of the principal vesicle, and gradually recover their original dimensions by pro-
pelling back to it the fluid which it injected into tliem. This kind of circulation is not
maintained in Amceba with the regularity that is elsewhere seen ; for MM. Claparede and
Lachmann observed that whilst only from half a minute to three minutes sometimes inter-
vened between the contractions, an interval of as much as five minutes might elapse between
the contractions, — a circumstance which shows how necessary it is to watch a Rhizopod for a
sufficiently long time, before coming to a conclusion as to the absence of a contractile vesicle.
It is not likely, however, that the movement of fluid which it seems to be the action of the
contractile vesicle to sustain, is completely suspended during so long an interval ; and as
tlic contractile vesicle was observed to be undergoing a continual change of bulk, it seems
probable that it was executing partial contractions during this period, and M'as refilled in the
intervals of these.

28. A singular modification of the ordinary Amoeban type is described by MM.
Claparede and Lachmann (.xxv, p. 441) under the name Podostoma. This creature (which
was found by M. Lachmann in great abundance at Berlin, in a vessel containing Algae and
Infusoria) may be readily mistaken for an Amwha until it exhibits the appendages which
are peculiar to it ; each of these resembles at its base a short broad pseudopodium, but from
the extremity of this there is put forth an elongated whip-like filament, which is in continual
motion like the jlagellum of certain Infusoria, and which lashes the surrounding water in
every direction. Any foreign particle which may come into contact with this filament is
retained by adhesion to it, and the filament then contracts into a spiral, disappearing at
last in the substance of its pseudopodium, with which it becomes re-incorporated, and
drawing into it the attached particle, which is at first brought to the rounded extremity of
the pseudopodium, is then received into a spoon-shaped depression that forms itself on this,
and then, by a gradual deepening of this depression, finds its way into the interior of the
pseudopodian expansion, and thence into the soft endosarc which constitutes a sort of "general
cavity of the body."

* These distensible vacuoles seem to have been mistaken by some observers for multiple contrac-
tile vesicles ; they have not, however, the well-definecl boundary of tliat organ ; and they do not
undergo the well-marked contractions which it presents at intervals.

OF THE RUIZOPODA IN GENERAL :—LOBOSA.

SI

29. From the simple naked Amceba a transition is presented to those testaceous forms
which accord with it in general structure, by the genus Fseudochhimys, in which the dorsal
surface is protected by a buckler or cai-apace (somewhat resembling the shell (f a FateJJa),
whose substance, however, is not dense enough to prevent its changing its form with that of
the body. In the P. patella described by MM. Claparede and Lachmann (xxv, p. 443), which
is common in ponds in the neighbourhood of Berlin, from six to ten " contractile vesicles" are
seen along its margin, Imt only a single " nucleus" can be distinguished.

30. Of the testaceous Amcebina there are two principal types ; the ArceJltB, which form a
membranous " test," possessing considerable firmness in itself; and the Difflugia, in which
firmness is imparted to the " test" by the adhesion of foreign particles (such as grains of
saud or fragments of shell) to its external surface. Both are inhabitants of fresh water, and
are pretty generally diffused. They have been divided into many species, according to
supposed differences of the most trivial character, which extended observa,tion proves to be
altogether valueless.

31. The "test" oiArcdla is ordinarily of nearly hemispherical form, the circular plane which
closes it in being perforated by a large aperture, from which the pseudopodia are put forth
(PI. I, fig. 19) ; sometimes, however, it is deepened into the form of a vase or pitcher, wliilst
in other instances it is flattened or depressed. Its surface is usually marked with hexagonal

. facets, which are due to the thinning of the membrane at those parts ; and sometimes it
presents a larger pattern formed by bands or depressions passing round it in various directions.
The animal . creeps with the mouth of the shell downwards ; its pseudopodia, which resqmble
those of Amceba, being extended between the flattened side of the shell and the surface over
which it moves. According to MM. Claparede and Lachmann (xxv, p. 444) ; the number of
" contractile vesicles" in ArccUa is very variable, and may increase with the bulk of the animal ;
they are always disposed around the periphery of the hemisphere. Although individuals are
sometimes observed to possess only a single " nucleus," yet this body is generally repeated
several times ; and these multiple nuclei may be seen to form a ring interior to the contractile
vesicles, which they may equal in number, as many as from ten to fifteen having been
observed. The Arcella may be observed to change its " test" many times during the course of
its life, not having any power of enlarging it. When the sarcode-body has become too
bulky for its envelope, it projects from the aperture of the test, from the cavity of which it
almost entirely withdraws itself ; and on the surface of this projecting portion a new test is
formed, which often differs from the old one in those characters which have been considered
to diS'erentiate species. At first, the new test is thin, transparent, and colourless ; but it
gradually becomes thicker, more opaque, and of a light yellowish-brown colour. The old and
the new tests are applied to one another, aperture to aperture (a condition which seems to
have been mistaken for an act of " conjugation") ; and the sarcode-body passes alternately
from one to the other, until at last, when the new test has acquired sufiicient consistence,
the Arcella entirely quits the old one, which very commonly splits under the violence that
seems involved in the final separation (xxv, pp. 44.5, 446). The "test" of Bijjlugia (fig. 20)
is usually more or less of a spherical or ovoidal shape, but is sometimes more elongated into
the form of a pitcher or a flask ; its aperture is generally somewhat notched. When

28 OF THE RHIZOPODA IN GENERAL :— RETICULARIA.

freed from adhering particles, its membranous base is thin, transparent, and colourless ;
sometimes it extends into spine-like processes, by which the test adheres to a fixed point
of attachment. The animal of BiJJlugia appears closely to resemble that of Arcella, but has
not been so carefully studied.

Order RETICULARIA.

32. As each of the preceding Orders contains both naked and testaceous forms, so
do we find that with the proper Foraminifera furnished with calcareous shells, there must
be associated (in virtue of the close conformitj^ in the nature and actions of their
sarcode-bodies) animals which only form a membranous " test," and some even which seem as
destitute of any protective envelope as an Amaba or an Aciinophrys* An example of this last
kind, which afi'ords an admirable illustration of the essential features that distinguish this
group (^ 11), is presented by the Lieberhihnia, a very remarkable Rhizopod, which has been
found in the neighbourhood of Berlin, by MM. Claparede, Lachmann, and Lieberkiikn
(xxv, pp. 464-466). t The body of this animal (PI. II), which measured about l-16th millim.
(l-400th inch) in its longest diameter, was formed of a mass of granular protoplasm not pre-
senting any distinct differentiation of "endosarc" and "ectosarc," and destitute alike of
"nucleus" and "contractile vesicle," but including a large number of "vacuoles" filled with a
homogeneous liquid. From one portion of this mass there issued a sort of stem, from which
all the pseudopodia diverged ; and this stem was enveloped in a transparent sheath, which
might be traced, as a thin pellicle, over the whole surface of the body. From this stem the
granular protoplasm extended itself into branches, whicii ramified with extreme minuteness
and to an extraordinary distance, their length in proportion to the diameter of the body
being nearly three times that which is represented in the plate. Wherever these ramifying
pseudopodia came into contact with each other, the substance underwent a complete fusion
or coalescence ; and thus a network was formed, which might be described as a sort of
animated spider's web, and which was admirably fitted for the acquisition of food. Any
small particles that come into contact with these pseudopodia were held to their surface by
adhesion, and then partook of the general movement of the granules included in the proto-
plasm to be presently described. But when larger bodies were thus entrapped, they became
enclosed in a sort of sheath of protoplasm formed by the blending of the neighbouring
pseudopodia whicli applied themselves to its surface ; and by the progressive contraction of
this they were drawn towards the body, as in the Adinoplinjs (1 14). In one instance a large
Stentor thus captured was seen to make its escape, carrying with it a portion of the pseudo-
podial expansion of the Lieherhiihiia. The granules so abundantly distributed through the pro-
toplasm of the body and its extensions were obviously for the most part of external origin ;
many of them being particles of chlorophyll derived from vegetable organisms that had been

* On this group see especially iv, xxv, x.xxiii, xxxv, xxxvr, lxxxiv, xcvii.

t The animal described by Professor Bailey (iv) under the name of Pamphagus mulabilis seems to
have been nearly allied to this, if not identical with it.

OF THE RHIZOPODA IN GENERAL :—RETICULARIA. 29

taken-in as food, whilst the introduction of others, that happened to he on the surface of the glass,
took place under actual observation. These granules were in a state of continual movement,
passing from the interior of the body and along the stem and branches of the pseudopodial
expansions towards the extremities of these, and then back again into the interior of the
body, in the manner that will be more particularly described in Gromia. The current was
rapid, and seemed to attain its maximum of intensity at the surface of the pseudopodia. It
was noticed in this interesting animal, which was kept for several days under observation,
that the pseudopodia were always most expanded in the absence of light, being splendidly
displayed when the slip of glass was first brought out of darkness and placed upon the stage
of the microscope ; but that after a few moments they began to retract themselves, their
viscid substance flowing rapidly towards the body with a wave-like motion ; and in a short
time it became impossible to recognise a Rhizopod in the dark motionless mass beneath the
microscope.

33. In the Gromia, some forms of which inhabit fresh water, whilst others are marine,
the sarcode-body, which is of essentially the same character with that of Lieherkiihnia, is
enclosed in a yellowish-brown membranous " test " of ovoidal shape, with a single round
orifice of moderate size, through which the protoplasmic substance extends itself from the
interior through the surrounding medium (PI. Ill, fig. 2). When the animal is in a state of
rest, the whole of this is drawn within the test; and when its activity recommences, single
fine processes are first put forth, which move about in a sort of groping manner until they
find some surface to which they may attach themselves. When this attachment has taken
place, new sarcode flows irtto them, so that they speedily increase in size ; and they then
elongate themselves by sendit^g out finer ramifying processes, which, in diverging from each
other, come into contact with' those proceeding from other stems, and, by mutual fusion, form
a set of inosculations or connecting bridges between the different systems of ramifications, so
that the whole becomes a complicated network extending to a distance of six or eight times
the length of the body. This network continues to undergo incessant changes, new filaments
being put forth in diff'erent directions, sometimes from its margin, sometimes from the midst
of its ramifications, whilst others are retracted. Not unfrequently it happens that at a spot
where two or more filaments meet and fuse together, a lamina is formed by an expansion of
the viscous protoplasm that flows towards this point; and from such an expansion a new set
of thread-like processes is given off", as from the central body, of which several examples are
shown in the figure. It is not only, however, in the protoplasmic substance directly as it
issues from the mouth that the pseudopodia originate ; for this substance is seen to
extend itself over the surface of the test, and may put forth pseudopodia from any part of it.
The greater development of these at the posterior extremity of the shell would seem
to indicate that they are employed for fixing it, and thereby cnaljling the animal to put
forth more power when seizing and drawing into itself as food living creatures that can
struggle against its ensnaring action. (The greater part of the Foraminifera are firmly fixed
by the adhesion of their shells to the surfaces of Algse, Zoophytes, Mollusks, &c.) Any minute
particle which may chance to come into contact with a pseudopodium, and which is retained
in adhesion to its viscid surface, soon becomes imbedded in its protoplasm, and is subjected
to the general movement to be presently described. But when a larger body is thus

30 OF THE lllIIZOPODA IN GENERAL :—RETICULARIA.

entrapped, a number of pseudopodia apply themselves to its surface, and a sort of flux of
their viscid protoplasm takes place towards it, until it becomes ensheathed with this
substance, as shown in the case of the Diatom entangled amongst the pseudopodia on the
right side of the figure. A reflux of the protoplasm of the pseudopodia then takes place, and
the body entrapped by them is gradually received into the mass of sarcode lying outside the
mouth of the test, through which it passes into its interior if not too large to find
admission. The lorica of Diatoms, portions of Confervm, and other similar bodies, bearing a
considerable proportion in length to the whole diameter of the test, may often be distin-
guished in its interior, as shown in fig. 2. — As the form of the test of Gromia does not
admit of any addition being made to its capacity, so as to accommodate it to the growth of
the contained body, it appears probable that the latter (like Arcella, "f 31) quits it, and forms
a new test whenever it has outgrown the old one ; and it does not seem unlikely that an
accumulation of indigestible substances may be got rid of at the same time, as the enclosure
of the body in a firm envelope must prevent these from being ejected from time to time
through an extemporised anus, with the facility which we have seen to characterise the
process of defecation in the naked Rhizopods.

34. Through tlie whole of tlie protoplasmic network, a movement of granules is con-
tinually taking place, chiefly in two directions — from the bod)' towards the extremities of the
pseudopodia, and from these extremities back to the body again. This movement may be
seen in every one of the processes ; but it is only in the broader filaments containing
numerous granules, that two streams can be seen passing at the same time in opposite
directions. In the finest filaments, whose diameter is less than that of the granules, the
latter glide along their surface at distant intervals, each passing up as far as the termination
of the filament, and then returning, sometimes meeting and carrying back with it a granule
advancing in the opposite direction. Even in the broader processes, granules are sometimes
observed to come to a stand, to oscillate for a time, and then to take a retrograde course, as
if they had been entangled in the opposing current — just as is often to be seen in Ckara.
When a granule arrives at a point where a filament bifurcates, it is often arrested for a time
until drawn into one or the other current ; and when carried across one of the bridge-like
connections into a difi'erent band, it not unfrequently meets a current proceeding in the
opposite direction, and is thus carried back to the body without having proceeded very far
from it. This curious circulation, as already pointed out (f 11), so nearly resembles the
cyclosis that takes place within the cells of PJant.s, as to leave no reasonable doubt that the
conditions of the two sets of phenomena are essentially the same.

35. In one large section of the Foraminifera, of which Miliola may be taken as the type,
the calcareous "shell," whether monothalamous or polythalamous, is formed upon the same
plan as the "test" of Gromia ;* the wall of each chamber being perforated by no other openings

* Althougli the author lias here followed the example of other Systematists in separating Gromia
and its naked allies from the true Foraminifera, he is by no means certain that such separation, h(?wever
convenient in practice, is scientifically justifiable ; since the difference in the coinpositiou between the
membranous "test" of Gromia and the calcareous "shell" of Miliola scarcely seems to him a character

OF THE RIIIZOPODA IN GENERAL :—RETICULARlA. 31

than those which communicate with tlie adjacent chambers, and the last-formed chambers
having only a single orifice* of communication with the exterior, from which alone pseudopodia
are put forth (PL III, fig. 3). But all these openings are usually so free, that no obstacle can
exist to a transmission of nutrient materials obtained by the pseudopodia put forth on the
exterior, to the segments of sarcode-body that are furthest removed by it, by a circulation of
granules through the entire mass analogous to that which has just been described ; and thus
the physiological condition of the animal of Miliola and its allies may be considered to be in
all essential respects the same as it is in Gromia. This will still be the case, even when the
number of such segments is immensely multiplied by the subdivision of the principal sections,
as in the animal of Orbitolites (PI. IV, fig. 14), Orbiculina, and Alveolina ; and the evidence
which the author has been fortunate enough to obtain in regard to the first of these types is
sufficient to show that there is no indication of deficient vitality in the portion of the sarcode
body which occupies the centre of the largest disk, the character of its substance being
precisely the same throughout.

36. A very different condition presents itself, however, with the two great groups
(together constituting by far the largest proportion of the entire series), of whicii Rotalia and
Operculina may be regarded as the types. For in these tiie apertures in the septal planes by
which the chambers communicate with each other, and by which the special communication
is established between the last chamber and the exterior, are so much narrowed that they
are sometimes not easy to be discovered ; but, on the other hand, the lateral walls of the
chambers are everywhere perforated, more or less closely, with pores for the exit of pseudo-
podia. Hence when a living Rotalia is under observation, its pseudopodia are seen to extend
themselves from every part of its surface (Plate III, fig. 1), and not to proceed only from the
orifice of the last chamber, as in IlUiola. When the pseudopodia have been entirely retracted,
however, it is generally observable that those first put forth proceed from the orifice (or
orifices) of the septal plane of the last chamber; and frequently a considerable time elapses
before the pores of the lateral walls give exit to protoplasmic filaments. , Often, again, these
filaments are put forth only from the two or three last-formed chambers. Still, when such an
animal has remained long undisturbed, its pseudopodia may be seen to extend themselves
from all the pores on its surface. If these are used for the introduction of alimentary
materials into the body, it is obvious that such materials only can thus enter, as are in a state
of sufficiently fine division to pass through these pores. No difficulty need be felt on this score
in the case of the Rotaline group, in which the diameter of the pores, being commonly as
much as 1 -3000th of an inch, allows the passage of pseudopodia of by no means the smallest

of sufficient importance to differentiate groups which are so intimately allied in their general physiological
conditions, especially when it is borne in mind that some of the Milolida form their shells, after the
manner of Difflugia, by the agglomeration of particles derived from without, instead of by an e.xudation
from within. Moreover, if Gromia be regarded as the monothalamous type of the Milioline series, it
naturally fills a place exactly parallel in rank to that of OrbuUna in the Rotaline.

* The single large mouth is sometimes replaced, as in Peneroplis and Orbitolites, by a series of
pores ; but these, being limited to the " septal plane," have no relation whatever to those which allow
the passage of pseudopodia through the lateral walls of the chambers of Rotalia and Oiierculina.

32 OF THE RHIZOPODA IN GENERAL:— RETICULARIA.

size. But in the Operculine the diameter of the pores is so much smaller, — being commonly
no more than 1-1 0,000th of an inch, and often less, — that only the very finest pseudopodian
threads can issue from them, and only the minutest granules can be received into them.
Certain facts in the structure of the shell, to be hereafter detailed (Chap. II), render it almost
certain that the protoplasmic substance extends itself at certain times, if not constantly, over
the whole exterior of the shell, as in Gromia (^ 33) ; and hence it is by no means impossible
that the digestive process may really be performed in this external layer, so that only the
products of digestion may have to pass into the portion of the sarcode-body occupying the
cavity of the shell.

37. The sarcode-body of such Foramini/era as have been observed in the living state, is
observed to be more or less deeply coloured ; its tint being in some instances a yellowish-
brown, in other cases a crimson-red. This colour seems in some instances to be uniformly
diffused through the whole mass of the sarcode, probably owing to the fine state of division
of the particles which possess it ; but in the larger forms it occurs in much larger and more
scattered masses, which appear sometimes to be collections of granules, and in other
cases to be vacuoles filled with a coloured liquid. In the polythalamous Foramini/era it is
nearly always to be observed that the colour is deepest in the segments of the body which
occupy the oldest chambers, and that it fades progressively in the segments which intervene
between these and the one that occupies the last-formed chamber, which is often nearly colour-
less. There is strong reason to believe that the colouring material is directly derived from
external sources, thougli modified in some cases by the agency of tlie animal itself. It was
found by Schultze, that he could increase the intensity of the colour, and cause even the
last-formed segment to be dyed with it, by feeding the animals with substances fitted to
impart it ; whilst, on the other hand, by depriving them of food that would furnish colour,
he could reduce the older segments to almost the same state of deficiency in this respect as is
usually presented by the last segment alone. It is stated by Schultze that the colouring
matter of Foramini/era, when treated with dilute sulphuric or hydrochloric acid, is changed
to an intense verdigris green ; and by dilute nitric acid, first to green and then to yellow.
Concentrated sulphuric acid destroys the colouring substance, but when combined with sugar
renders it green. By concentrated solutions of potass and soda, the coloured granules are
dissipated without change ; and in ether and alcohol they are readily and completely
dissolved. In these reactions the colouring matter agrees with that of the Dialomacece, from
which tribe the greatest part of the food of the Foramini/era is probably derived.

REPRODUCTION OF RIIIZOPODA.

38. So little is at present known of the manner in which Rhizopods belonging to any of
the foregoing types propagate their kind, that it seems preferable to bring together
the principal facts hitherto recorded respecting the mode of reproduction in all these
groups ; more especially as they will be found to bear a very close resemblance to one
another.

39. The deficiency of structural differentiation, either morphological or histological, which

UEPROUUCTION OF IIHIZOPODA. 33

is so remarkable a characteristic of this group, would lead us to infer that, as every part of the
homogeneous sarcode seems possessed of the same attributes in regard to the pliysiological
activity of the individual, so it should be equally able to participate in that modification of
the ordinary processes of nutrition wliicii gives origin to new and independent beings by
continuous growth. There is evidence that this is actually the case ; for not only do portions
of the sarcode-body detached from the principal mass forthwith comport themselves after the
manner of that from which they have been separated, — the sarcode forced out by crushing
the shell of a living Arcella, for example, putting forth lobose extensions on the Amoeban type,
whilst that forced out by crushing the shell of a living Poh/.^foiJi<'lla puts forth the slender
branching pseudopodia of the Reticularian (Plate I, fig. 12), — but there is every reason to
believe that such detached portions can continue to maintain an independent existence. Thus
it is not unfrequcntly seen in AiiKcba that when a pseudopodial process or lobe of the body
has been put forth to a considerable length, and has become enlarged and fixed at its
extremity, the subsequent contraction of the connecting portion, instead of either drawing the
body towards the fixed point, or retracting the pseudopodial lobe into the body, causes the
connecting band itself to become more and more attenuated until it gives way, leaving the
terminal enlargement altogether detached ; and this portion speedily shoots out pseudopodial
processes of its own, and behaves itself in all respects as an independent Amce.ba. Still more
satisfactory evidence to the same effect has been obtained by myself in my detailed study of
Orbitolites ; for not only have I met with numerous specimens in which the loss of any portion
of the disk was repaired by a new growth taking place in every respect upon the regular type
(Plate IV, fig. 2(i), but I have been fortunate enough to obtain a specimen (fig. 27) in which
a new disk has been formed from what was obviously nothing else than a fragment broken
away from the margin of a much larger one. — Since, therefore, in the more as in the less
specialised types of Rhizopod conformation, any portion of the sarcode-body can thus
comport itself as an independent organism, it may be reasonably inferred that this is true
of the entire group, and that the detachment of such portions, after the manner of the
gemmation of higher plants and animals, is one mode in which Rhizopods are ordinarily
multiplied. And such would seem to be the most probable explanation of the appearances
seen by Schneider (xciii) in Dijliii/ut ; which indicate that a whole colony may be formed
by gemmation from the pseudopodial lobe of one individual.

40. Inferential evidence to this effect is abundantly afforded by the study of the polytha-
lamous types of Foramiiiifera ; for in every case in which it has been hitherto possible to
examine the sareode-body of these animals, its character has been found to be uniformly the
same throughout, every segment precisely repeating every other, save in the difference of
colour already noticed, and in certain appearances occasionally presented by the outer
segments (^ 48), which are probably indicative of a more special kind of reproductive action.
The entire sarcode-body of an Orbitolites (Plate IV, fig. 14), for example, is made up of an
aggregation of segments that have been successively put forth, by a process essentially
resembling gemmation, from the primordial segment which continues to occupy the central
chamber; and it affords one of the best examples which the Animal Kingdom can present, of
that " vegetative'' or " irrelative" repetition which is an essential feature of all low grades of
organization. Every one of these segments, there is strong reason to believe, could maintain

5

34 OF THE RHIZOPODA IN GENERAL.

an independent existence ; and yet so long as it remains in connection with the rest, it shares
a common life with them, the nutrient materials being introduced in the first instance through
the marginal segments, and being transmitted by protoplasmic circulation (ft 32 — 34) through
the entire mass. But in a large proportion of the polythalamous Foramiiiifera, the segments
thus successively formed are much more completely isolated from each other than are
those of OrUtolites ,• and there are several in which the chambers of the shell that
envelope these segments have so little connection with those that precede and follow
them, as to be easily detached from them and from each other. This is the case, for example,
with GlohigmiKc, and with many of the Nodosaria> ; and there is reason to believe that the
separation of their parts, which can be produced by very slight external violence, ma)'
be a means of their nudtiplication and diffusion.

41. Besides this, which may be considered the mofst general method of reproduction
among Rhizopoda; other more special forms of that process are' indicated by observed facts.
In those types which exhibit, in the differentiation of "ectosarc" and " endosarc," and in the
presence of a nucleus, the nearest approach to the condition of cells, multiplication takes place,
as in growing cells generally, by a process of binary subdivision. This may often be witnessed
in ActinopJiri/s, round whose spherical body an annular constriction forms itself, which
gradually deepens so as to separate its two halves by a sort of hour-glass contraction
(Plate I, fig. 4) ; and the connecting band becomes more and more slender (fig. S), until a
complete separation of the two halves occurs. The process of fission, which may be completed
within half an hour from its commencement, seems to take place first in the contractile vesicle;
for each segment very early shows itself to be provided with its own (Fig. 4, v, v), and the
two vesicles are commonly removed to a considerable distance from one another. The
segments thus divided are not always equal, and sometimes their difference in size is veiy
considerable. — The like process of duplicative subdivision has been witnessed also in Amceba.
Whether in either case this subdivision commences in the nucleus, or extends through it
subsequently, has not yet been ascertained.

42. It is affirmed by Schneider (xciii n) that Amccba sometimes passes into an encysted
condition. He observed it first to become globulai', and then to form a firm membrane on one
side, whilst the other portion maintained its peculiar character and actions. (In this state it seems
to have resembled the A. bilimbosa of Auerbach, Plate I, fig. 1 7.) By degrees the membi-ane
extended itself over the whole body, the moveable portion constantly becoming smaller, until
at last a completely closed cyst was produced, in the clear interior of which a round nucleus,
with a reddish halo, exactly like that of Polytoma and other Monadina, might be distinctly
observed. To what this encysting stage leads, there is at present nothing to show. — A
change which seems to be of the same nature has also been observed b)^ Schneider (xciii)
in BiJJfiif/ia, and by Schidtze (xcvii, p. 25) in Lagynis Baltica (Plate I, fig. 21, b).

43. On the other hand, a junction of two individuals has been seen to take place in
Adinophrp, which has been supposed to correspond with the " conjugation '" of certain
Protophytes. It is very doubtful, however, if this junction or "zygosis " involves a complete
fusion of the substance of the bodies which take part in it; and there is not sufficient evidence

RKPRODUC'J'ION OF RHIZOPODA. Sf)

that it has any relation to the act of reproduction. Certain it is that such a ''zygosis" may
occur, not between two only, but between several individuals at once, their number being
recognised by that of their contractile vesicles ; and that after remaining thus coherent for
several hours, they may separate again without having undergone any discoverable change.
Whether, by any process of a sexual character, germs are developed within the body, and
are then set free, must at present be regarded as quite uncertain ; the only reliable evidence
on this point being that which is afforded by the observation of Professor KiJlliker, that very
small individuals oi Jcfi//op/tr//s sometimes present themselves, measuring no more than -01 or
"02 millim. (l-2560th or l-12S0th incli), and presenting very few and inconspicuous granules.
But these may be gemmae or small segments separated by the process of subdivision, and not
sexual products. And it must for the present be held to be quite uncertain, whether the
body wliicli we know as Aciinoplirijs does not go through some entirely different phase, before
the completion of its life-history. — A like process of conjugation has been seen to take place
also in several AinmhiiKE, testaceous as well as naked ; and the same doubt exists whether
this " conjugation '' has any import at all corresponding to that of sexual union among the
higher animals, and whether the being which is known as Amceba is anything more than one
form of an organism, whicli would present itself to us under other very diverse aspects if the
whole of its life-history were known to us.*

44. Certain appearances, however, have been obsei-ved by Mr. H. J. Carter (xxii,
pp. 223-233) among Amahina and Actinophnjna, which may be provisionally accepted as
indicating that true sexual products are formed in the interior of their bodies, and arc after-
wards set free by their disintegration. In Amaba the formation of the male apparatus appears
to commence by an increase of size in the vesicular portion of the nucleus, which also becomes
more or less globular (Plate IV, fig. 6, a) ; and its contained aggregation of granules then aug-
ments so as to occupy a third of the interior of the animalcule, and undergoes successive
binary subdivisions, by which it is broken up into numerous segments. These segments
assume a circular compressed or globular form, and continue entire until the granules
(spermatozoids ?) of which they are composed become fully developed, when the latter
acquire the power of locomotion, and then separate from each other, the original containing
vesicle in the meanwhile disappearing. In this way some individuals out of a group of
Amceba radiosa bearing such granules were seen moving about, even when so reduced that
hardly anything but their external pellicle and the one or two spherical segments of the
granulated nucleus that remained in their interior were left. Sometimes these segments
are evidently held together by a soft mucous envelope, which, being polymorphic, assumes
the form of Actimphriis (fig. 7), and exhibits locomotive power ; while in other instances tliis
capsule becomes firm, transparent, and spherical ; and the granules do not leave it until
they become endowed with independent activity. When the latter is the case, the sperma-

* The Author considers that it would be foreigu to tlic purpose of the present work, were lie here to
entur upon a discussion of the curious observations of Hartig, Carter, and others, who maintain tliat
Amceba and Actinophrijs, or organisms undistinguishable from them, are formed as individualised seg-
ments of protoplasm within Vegetable cells, entering upon their independent Animal life when set free
from these.

36 OF THE RHIZOPODA IN GENERAL.

tozoids (?) may be seen, if fully developed, to be bounding about in the interior of their
capsules, while the capsules themselves are still rolled on in the sarcode of the Amcebn under
progression. At other times, the whole mass of the spermatozoids (?), all separated and freed
from their capsules, mav be seen to be diffused through the body of the Aniceba whilst still
in active polymorphism and locomotion. Lastly, the parent sometimes dies in this state ; and
then the mass of spermatozoids (?) may be seen to undergo gradual disintegration, as the
granules, by twos or threes or more, disentangle themselves from the sarcode, and bound off
into their new element. — The development of granvdar spermatozoids (?) has been observed
by Mr. Carter to take place after almost exactly the same fashion in Eiif/Ji//jha aheoUdu (fig. 9), in
which their diameter averages from l-16,000th to l-12,000th of an inch; and similar bodies
have been seen bv Schneider (xcin) to develope themselves from the nucleus of Diff!(i(/ia.

45. Again, not only Amxeha, but Eitt/l^/pIi(V, Diffliif/ice, and ArcdUna, have been frequently
observed by Mr. Carter to contain in the midst of their sarcode a number of discoid or
globular bodies having the appearance of ova (Plate IV, figs. 8, 10, 11). At an early stage
of their formation each of these bodies consists of a transparent capside, lined with a faint-
yellow film of semitransparent matter, which, subsequently becoming more opaque and
yellowish, also becomes more marginated and distinct.* They are very commonly accompanied
by active molecular granules. Their number is sometimes so great, that, as in the specimen of
Amoeba verracoHa represented in fig. 8, the entire body comes to resemble an ovisac filled
Avith granuliferous germ-cells. In Euglypha alccolala they are first seen, to the number of
from four to fifty, congregated round the nuclear vesicle, though afterwards they become
diffused through the sarcode-body generally (fig. 10) : their diameter averages from 1 -4000th
to 1 -3000th of an inch, or something less than that of a human blood-corpuscle.

46. Although the development of spermatozoids (?), and of ovules (?) takes place more
profusely in distinct individuals than in the same, yet it is by no means uncommon to see
individuals of Em/Iyplia akeolata containing both kinds of bodies (fig. 11) : there is no such
gradation between them, however, either in size or aspect, as would suggest the inference
that the one form originates from the other.

47. Of the subsequent history of these bodies very little has been yet ascertained, and it
cannot be stated with any approach to probability in what way their development and actions
are related to the " conjugation" already mentioned as not unfrequcntly to be seen between two
or more Amoebina or Actiiiopliri/na. It is stated by Mr. Carter that the granular spermatozoid (?)
development does not take place until after conjugation ; and that after Enr/h/plice have united
themselves, not only in pairs but triply and quadruply, it is common to see only ovules
developed in all the individuals of one group, and spermatozoids in those of another.
In Euglijijhcp (fig. 11) which contained both ovules (?) and spermatozoids (?), the former were
often observed to be surrounded by actively-moving swarms of the latter ; and the same is

* The "seed-like bodies" of Spongillu Lave been found by Mr. Carter to contnin numerous
transparent, globular sacs, each of which includes a greater Or less number of ovules f>) resembluii,'
those described above. Thus, each of these sacs may be cousideied as the representative of an Amoeba.

REPRODUCTION OF RHIZOPODA. 37

also observable in Sponfjilla, in which Mr. Carter thinks that he has seen the incorporation of
one of the spermatozoids (?) with an ovule (?), in a manner that indicates the act to be one of
fecundation. He has been able to watch the ovules from their first appearance until they
acquire the aspect of simple Rhizopods with a power of putting forth pscudopodia ; and he
believes that when they have attained this condition they are set free by the death of the
parent, and, escaping from the cavity of its test, soon form new tests for themselves. By his
subsequent observations upon Am(eha verrucosa (xxiii, p. 37), Mr. Carter was led to believe
that each ovule in that species gives origin to a number of independent " polymorphic" cells,
resembling those which he had previously described as constituting the first product of the
ovum of Spont/illfi : and that these pass several months in their immature condition, before
taking-on the characteristic aspect of the parent.

48. Of the special modes in which Reproduction is effected in Foraminifera, scarcely
anything is yet known. It was observed by Dujardin that the protoplasmic contents of the
chambers of Tnmratulina sometimes group themselves together as spherical masses ; and I
have met with tlie same kind of aggregation in the sarcode of the superficial chambers of
OrhHolites (Plate IV, fig. 1), the spherules averaging about l-3200thof an inch in diameter.
Lying in the midst of the sarcode of the same animal, 1 have occasionally found other bodies
(fig. 2, /< — (/), sometimes resembling simple cells, sometimes like cells undergoing binary sub-
division, having a firm envelope, and retaining the crimson hue of the animal substance even in
spirit-specimens ; their diameters varied between 1 -650th and l-300th of ai^ inch. These seem
analogous to the dark splierules observed by Scliultze (xcvii, p. 27) in certain Rotnlla, some-
times occupying all the chambers (fig. 3), in other instances confined to the last one or two; the
ordinary sarcode co-existing in the same shells, but not putting forth pseudopodia. These
spherules were composed of a collection of dark molecular matter, not enclosed in a distinct
membrane, but held together by some uniting medium ; and they were especially remarkable
for their resistance to reagents, not being acted on by sulphuric, nitric, or hydrochloric acids, or
by boiling alkalies. The Botalice containing these dark spherules were isolated by Schulze, and
kept for many weeks, but no change could be observed in them ; and it must at present be
regarded as quite uncertain whether the foregoing phenomena have any relation to the
reproductive process.

49. More satisfactory information was subsequently obtained by the same excellent observer
(xcvni) in regard to the production of the young of j\fUUil(i. Having obtained some
large living specimens of the ii-UocuUni' form of Miliola, he kept them for some time under
inspection, and found that some of them, after remaining adherent to the sides of the glass
vessel during from eight to fourteen days, became invested with a brownish, slimy matter,
which more or less completely obscured the view of the external characters of their shells.
After the lapse of some days longer, minute, sharply-defined granules could be seen in this
substance with the aid of a lens (Plate IV, fig. 4, a), and these gradually loosened themselves
from the soft enveloping mass, and separated further and further from the shell wliicli it
surrounded. Microscopic examination of these corpuscles, of which as many as forty were
counted round a single progenitor, proved that they were young MUiolce. When viewed by
transmitted light, thev presented a pale, yellowish-brown, calcareous shell, consisting of the

38 OF THE RHIZOPODA IN GENERAL.

central globular primordial chamber in which all Foraminifera seem normally to commence,
partly surrounded by a closely applied tubular part, not separated from the preceding by any
distinct septum (fig. 4, b). In a short time, the young animals put forth their pseudopodia
from the aperture of the shell, and crawled about upon the surface of the glass. The shell
was sufficiently transparent to enable the contained sarcode-body to be examined with high
magnifying powers ; and it was seen to consist throughout of the ordinary protoplasmic
substance, without any vestige either of nucleus or of contractile vesicle. The latter half of
the tubular volution of the young shells was observed not to be completely occupied by the
animal substance, whilst the central portion was densely filled, the oil-particles especially
accumulating in the latter position. When the calcareous shell of the parent Miliola was
carefully broken up, it was found to contain only trifling remains of fine granular sarcodc,
Avhich did not put forth anv pseudopodia, and in which no vestige could be traced of anything
resembling a young animal in progress of development. Hence it would appear as if the
principal part of the body of the parent had been transformed into the bodies of the brood of
young, which seem to quit the parent in an advanced condition, probiibly acquiring their
shelly envelope before leaving that of their progenitor. — Prof. Schultze has since (xcix, p. 320)
had the opportunity of observing a like phenomenon in the case of a small RoUdia, about
1-1 00th of an inch in diameter, which was living attached to the interior of a glass bottle.
The yellowish-brown contents, especially of the larger chambers, exhibited a peculiar coarsely
granular consistence, observable even with a strong lens ; and on breaking up the shell, which
contained ten chambers, twenty or thirty small Polythalamia were found in its interior. These
were all of equal or nearly equal size, and consisted of three mutually adherent, nearly
globular chambers, of which the first and innermost was the largest, and was filled with large
pigment-vesicles, resembling fat-globules, while the other two were colourless. The shell
was very thin and brittle, and corresponded in the dimensions of its chambers with the
first-formed portion of that of the parent. On watching other individuals which presented
the same coarsely granular appearance, it was observed that a multitude of granules suddenly
appeared in their neighbourhood, which proved, on examination, to be young Polythalamia,
of the same size and form as those artificially freed from their parent, and only differing from
them in showing the yellow colour in the second as well as in the first chamber. Whether
they made their escape by the rupture of the shell of the parent. Prof. Schultze did not
succeed in determining with certainty, but appearances favoured the belief that such was their
mode of exit. — Dr. T. Strethill Wright has lately (cxii, p. 362) confirmed an observation
formerly made by Ehrenberg, as to the presence of the young of SpirilHna vivipara in the
interior of the shell of the parent.^I may add that I have in my possession a
number of very young specimens of Orbitolitcs, consisting simply of the primordial chamber
and the one immediately surrounding it (Plate IV, fig. 22), which were removed by Mr. W.
K. Parker from the deeply-channeled margin of one of these large plicated forms of Orh'i-
fnlites that present themselves in certain localities of the Polynesian Archipelago. In that
specimen they occurred in considerable numbers.

50. Whether the transformation of the sarcode-body of the parent into the substance of the
young occurs in the foregoing cases as the result of anything like a sexual act, or is e9"ected
(like the formation of zoospores among Protophytes) simply by the breaking up of the original

REPRODUCTION OF RHIZOPODA. 39

protoplasmic mass, is a question as to which there is not at present the sHghtest evidence on
either side ; and it is much to be desired that observers who have facihties for the study of
the reproduction of the Formmni/era should systematically and perseveringly investigate it.
The only observations yet recorded, that indicate the existence of a sexual process in Forami-
nifera, are those of Dr. T. Strethill Wright (cxii), who states that on examining a great
number of specimens of Gromio, ('ornuspira, Miliola, BoMia, and Orhuliiiu, he has repeatedly
discovered bodies which correspond to the " primitive ovum " of ^c«/(^//(«. They consist of
transparent spheres or ovoids, formed of a finely molecular substance, in which, however, the
molecules are masked or rendered indistinct by the highly refractive matter in which they
are imbedded. He was never able to detect either germinal vesicle or germinal spot in the
living specimens ; but in a specimen of Trunratuhva which had been hardened in spirit,
decalcified by dilute nitric acid, and then mounted with strong heat in Canada balsam (PI. IV,
fig. 5), four of the segments (r, c, c, c) each contain an ovum, which shows a germinal
vesicle and spot with the utmost distinctness, whilst the rest («/, d) present the usual
appearance of granular, low-refracting sarcodc. The ova of Gromia are small enough to
escape by the aperture of the "test;"' and as young Groiuia: are met with slightly larger than
these ova, it seems probable that the ovum is at once transformed into the body of the ofi^spring,
and that it directly acquires an envelope. But in Orhulina and Trtmcattdina the ova are of
much larger proportionate size, having in the latter case as much as ten times the diameter of
the primitive segment, and being far too large to escape by the aperture of the chambers
which contain them. Hence it is considered probable by Dr. Wright that the ova of these
genera undergo a polymorphic development of many months' duration, similar to that supposed
by Carter to occur in Amwha verrucosa (^ 47) ; and that each ovum becomes transformed by
fission (of which process he detected indications) into numerous amoeboid zooids, which escape
through the openings of the shell and form the primordial segments of future Rhizopods. The
observations of Prof. Schultze upon Rolalia, however, would rather lead to the inference
that the segments into winch the ovum breaks up remain in connexion with each other, and
constitute, not the primordial segment only, but the segments immediately succeeding it, in
each of the young, and that these escape by the rupture of the shell of the parent. — Specimens
occasionally present themselves which indicate that a partial binary fission of the germ may
take place at a period anterior to the calcification of the wall of the primordial segment.
Thus Prof. Williamson (ex) has described a twin monstrosity of Entosolenia (fig. 32, a), and
a similar example of Z)«^/«//«« (fig. 49), which have obviously originated in an incomplete
subdivision of the primordial segment ; and he states (p. xi) that " whenever such specimens
occur, it invariably happens that the two halves of the twin organism belong to the same
variety or type," — a fact of some importance as indicating that the transmission of varieties
is eS"ected, as in Plants, by those processes of subdivision which take place under the form of
fission or gemmation, whilst the origination of varieties is rather to be looked for in sexual
generation. Some curious examples of the same kind of " monstrosity by excess," occurring
in Orbitolitefi, have been described and figured by myself (xiii) ; and in those cases also.
Prof. WiUiamson's general statement was fully borne out.

CHAPTER III.

OF THE FORAMINIFERA GENERALLY ; THEIR CHIEF TYPES OP STRUCTURE AND
MODES OF GROWTH, AND THE PRINCIPLES TO BE FOLLOWED IN THEIR
CLASSIFICATION.

5L The group of Rhizopods which is known under tlie designation Foraminifera has
been shown in the preceding Chapter to be distinguished from the other great divisions of its
class, not only by that investment of the sarcode-body with a calcareous shell which constitutes
its most easily I'ecognised feature, but by such a peculiarity in the condition of the sarcode-
body itself, as seems to justify a marked separation of the animals which exhibit it from those
formed upon the type either of the Amwha or the Actinophrijs. That peculiarity (it may be
well to repeat) essentially consists in the absence of differentiation in the semi-fluid proto-
plasmic substance of which the body is composed ; its homogeneousness being especially
manifested in the freedom and minuteness with which its pseudopodial extensions subdivide,
and in the readiness and completeness of their coalescence wherever they come into contact
with each other, so as by their ramification and mutual inosculation to form a living-
network, along the threads of which a circulation of granular particles is continually taking
place. Of the Order Reticularia thus constituted so few other forms exist, that
it may be almost said to be synonymous with the group of Foraminifera; and it may
indeed be questioned whether in a classification based on physiological principles there is any
adequate ground for separating from the calcareous-shelled Miliola (^ 35) either Gromia
(•[ 33) whose" test" is membranous (probably chitinous), or Licbcrkuhnia (% 32) which has
no firm covering at all. So far as we yet know, there is no difference whatever between the
animals of these three types ; and to class them separately, still more to arrange Gromia and
Layyim (as Schultze has done, xcvii, p. o2) \i\\}a Arcella z.'ixADiJjhigia, on account of the unilo-
cular condition of the " test," would seem just as unnatural as it is now admitted to have been
to separate Hydra from the compound Hydroida, and Actinia from the compound Helian-
THOiDA, and to group together Hydra and Actinia as naked solitary polypes, whilst their
composite representatives were classified according as they form horny or calcareous
skeletons. Until, therefore, some more adequate ground bf differentiation shall have
been established than any at present known, the group of Foraminifera may be
considered as really coextensive with the Order Rhizopoda reticularia; and there

PRINCIPLES OF CLASSIFICATION. 41

seems the more reason for including Gromida and even Lieherkiihnia within its limits,
when it is borne in mind that in the limitation of the origin of the pseudopodia to one
part of the body these forms bear a closer relationship to the Foraminifcra of the MUioUne
series, than the latter do to those of the liotalinc, in which the pseudopodia seem to extend
themselves equally from any part of the sarcode-body.

52. Before enlarging upon the value of the differential characters just alluded to —
which will be shown to have such an important relation to certain peculiarities in the struc-
ture of the Shell, as to justify the employment of these as characteristics of the fundamental
divisions of the group — we must stop to inquire how far the separation of the Monothalaiiious
or Unilocular Foraminifcra, as an order distinct from the PoI^fJialamous or Multilocular (a
separation which has been adopted by D'Orbigny, Schultze, and Bronn), is to be regarded as
based on a right appreciation of their mutual affinities. It has been seen that, in common with
all the lower forms of animal and vegetable life, the Rhizopoda tend to multiply by a separa-
tion of continuously growing parts of their bodies, which may take the form either oi fssioii
or of gemmation, according as the original bod)'^ undergoes subdivision, or as it puts forth an
extension which eventually detaches itself. Among the Foraminifcra proper, whose bodies
are enclosed in unyielding shells, multiplication by fission cannot take place, except in that
early stage of existence in which the shell is not as yet consolidated (5[ 50) ; but extension
by gemmation may go on without limit. The progressive growth of the sarcode-substance
causes a portion of it to project beyond the aperture of the shell ; and this projecting portion
possesses all the attributes of the body of which it is an extension, and can maintain its exist-
ence with equal readiness either in a separate state (1[ 39) or in continuity with the stock of
which it is an offset. Although, therefore, there are certain types of Foraminifcra in which
such offsets appear invariably to separate themselves before the consolidation of their shell, so
that the original body never adds to the number of its segments and the shell remains
" monothalamous," — whilst there are others in which they ordinarily remain in connexion with
the original stock, so as progressively to augment the number of its segments and of the
chambers of its " polythalamous shell," often to an indefinite extent, — there is no such essential
difference between the physiological conditions of the newly formed segment in the two cases,
as would be required to justify the erection of the Monothalamia into a distinct order.* More-
over, we find that between these two groups there are gradational affinities of such a kind as
to render it impossible to separate them by a decided line of demarcation. For, on the one
hand, there are certain Monothalamous Foraminifcra which may be regarded as potentially
Polythalamous, the body and shell having the power of indefinite extension, but not exhibiting
any distinct segmentation; as is the case with Cornuspira and Spinllina, of which the former
is intimately related to the least speciaHsed forms of Miliola {% 104), whilst the latter is
scarcely less closely related to certain Rotalia. On the other hand, since there are certain
Polythalamia (f 40), the successive chambers of whose shells are so slightly connected

* No botanist would think of separating from their natural allies, and ranking together as a dis-
tinct order, those Plants which habitually propagate themselves by detached gemnue, such as Lunularia
vulgaris and Lemiia gibba (which are only known to reproduce themselves after this fashion), or
Dentaria bidbifera, Gtobba amarantina, and Lilimn bulbifenim.

6

42 OF THE FOEAMINIFERA GENERALLY :

as to be easily separable from each other by accidental violence, and of which the animals
can maintain their lives jnst as well when they are thus broken up into distinct segments
as when retaining their original connexion, such may be regarded as poientially Mono-
thalamous ; and the fact that the segments of sarcode, as they were successively budded forth
from the stock, formed their shelly investments before instead of after their detachment from
it, can scarcely be admitted by the physiologist as alone justifying an ordinal differentiation
which is not borne out by other structural or physiological diversities.

53. It was not unnatural that, in seeking for a basis on which to found an arrangement
of the multitudinous forms of Foraminifera which he for the first time brought together under
one distinct category, M. D'Orbigny should have attached primary importance to characters
so easily recognised as those which are produced by diversities in the plan on which the suc-
cessive segments are added one to another. For the varieties of form thus produced seem at
first sight easily capable of being reduced to a small number of primary types ; and it is only
by such a laborious and conscientious comparison of osculant forms as formed no part of M.
D'Orbigny 's method of study, that the essential conformity in plan of growth is discovered
which often exists between organisms arranged by him under different orders ; whilst it is
only by an equally painstaking examination of the internal structure of the shell, such as seems
never to have been even thought of by M. D'Orbigny, that those very marked characters are
brought to light, which often separate by the widest interval organisms grouped by him under
the same order, and which bring these respectively into intimate relationship with others
whose place in his series is very remote. Thus, when we come to speak of the genus
CristcJlaria, we shall find that it comprehends a series of straight, curved, and spiral forms,
agreeing with each other in all essential particulars save the direction of their axis of growth,
and presenting such a continuity in the gradation from the straight to the curved, and from
the curved to the spiral, as prevents any decided line of demarcation from being anywhere
drawn among them. So, again, we shall find that although, on the ground of conformity in
their plan of growth, Orbitolites and Cydochjpeus would be grouped together by M. D'Orbigny
in his order Ci/closter/ues, whilst Oriiculiiia, Penerojilis, and Operculina are placed in his order
Helicostef/ues, and Heferostegina in his order Enfomostef/ues, a careful comparison of the
essential features of their structure shows that not only have Orbitolites and Ci/clocli/peas
nothing in common but their cyclical mode of growth, but that Orbitolites is most intimately
related to Orbiculina (which often takes-on the cyclical mode of growth), and through it to
Peneroplis, whilst CyclocJypeus is scarcely less intimately related to Heterosteyina and through
it to Operculina. It may, in fact, be most safely asserted, thatj'Vaw of groicth is no more to be
regarded as an exponent of the really natural afiinities of the several generic types of
Foraminifera, than the number of stamens and pistils is of the natural affinities of Phanero-
gamous plants. The system founded upon each of these bases will doubtless, in many
instances, bring together types which have a real affinity to each other, simply because the
characters in question sometimes coincide with those of more essential value ; but such coin-
cidence is (so to speak) accidental ; and it much more frequently happens in the one as in
the other of these artificial systems, that they separate by a wide interval types which in
reality are closely related, whilst those which they bring into nearest proximity are essentially
diverse in organization.

PRINCIPLES OF CLASSIFICATION. 43

54. The foregoing remarks are scarcely less applicable to the classifications of Professors
Schultze (xcvii) and Bronn (xi) than they are to that of M. D'Orbigny; since by them,
as by him, the jjiau of f/roxolh is regarded as the fundamental basis of S3'stematic arrangement,
so that their primary divisions are eminently artificial. They have been guided, however, in
their subdivision of Orders into Families by a higher appreciation of the characters furnished
by variations in the texture of fl/e hJicII, than was entertained by M. D'Orbigny ; and they have
thus been led to a more natural grouping of generic forms than his classification usually
presents. — As neither of their systems, however, has yet found its way to general acceptance, it
scarcely appears necessary here to enlarge upon their defects ; these being necessary results
of the imperfect method of study whicli tlieir authors have followed; and the object of the
present work being to sTibstitute a classification, whicli, however incomplete, shall, at any rate,
present an approximation to a natural system, as being based on the whole aggregate of the
ascertainable characters of the several types, instead of on a single feature which affords no
reliable indication of their real aflSnities.

55. It is now universally admitted by Philosophical Zoologists, that the importance of the
characters furnished by the f^Icrleton, whether internal or external, of any animal, depends
entirely upon the relations which they bear to its general organization ; and that hence the
adoption of any such characters as a basis for classification can only be justified, when their
accordances and differences can be shown to be indicative of corresponding accordances and
differences in those parts of the organism whicli are of higher physiological import. Thus
the possession of a hivahe shell is universally admitted as differentiating the Mollusks which
bear it from those whose shell is univalve, the whole plan of structure of the animals in the two
cases being obviously different. But among " bivalve'' Mollusks there are two very distinct
types of structure (the Lamellibranchiate and the Palliobranchiate), whose essential dissimi-
larity, being only revealed by anatomical inquiry, would never have been recognised by the
mere Conchologist ; although, when he has once made himself acquainted with these types, he
finds no difficulty in distinguishing the shells they respectively include by the special
characters which they severally present. So among " univalve" Mollusks there is not less
diversity of type, shells composed of a single piece being found among Gastcropods, Ptero-
pods, and Cephalopods ; and the conformation of the shell is here so much less intimately
related to that of the animal by which it is constructed, that it is not always possible to refer
a shell with certainty to its proper place while the nature of its animal inhabitant is unknown.
Further, " univalve" shells are formed also by Annelida, and there are no well-defined characters
by which the tubes of a Serjjula (Annelid) and these of a Vermetm (Gasteropod Mollusk) can be
distinguished one from the other ; so that in a system of classification founded ujion the shell
alone they would be placed side by side, as would also the Crustacean Cirrhipedes and the
Gasteropod Chitons, because both these tribes of animals have their bodies protected by
multivalve shells. Among Zoophytes, again, whilst the " lamelliform" structure of the stony
Corals is so uniformly related to the Aetiniform type of organization, that the existence of
that structure in the oldest fossil affords a sure key to the nature of the animal which formed
it, the polyparies which constitute the skeletons of animals of the Ahyonian type are so
diverse in their composition and arrangement, that it only becomes safe to predicate the

44 OF THE FORAMINIFERA GENERALLY :

animal from the polypary, when each type of skeleton has been examined in connection with
the soft body it supports. On the other hand, we not unfrequently find that a close resem-
blance in the structure of the polypary masks an essential diversity in the organization of the
animal ; certain horny skeletons of H^/drosoa being scarcely distinguishable from those of
Poli/zoa, although the former belong to true Zoophytes, whilst the latter are members of the
Molluscous sub-kingdom.

56. It seems obvious, then, that no classification of Foraminifera can be thoroughly
satisfactory, which is based rather on the characters of their shells than on those of the
animals by wliich those shells are formed ; and it is unfortunate tliat our knowledge of the
latter is as yet so imperfect, as to afford us but a ver}^ slight foundation for a natural arrange-
ment of the group. It may be questioned, indeed, whether the extreme indijferenHsm of
structure which seems to be a general characteristic of the Rhizopod type and to reach its
acme in the Foraminifera, will not always prevent the systematist from finding the study of
the animal of much avail to him ; and whether he will ever be relieved from the necessity of
placing his chief reliance on those features in the structure of the shell, which may be
regarded as most surely indicating the potentialities of the apparently homogeneous jelly-like
mass which it encloses. Such, at any rate, must be his method of procedure under existing
circumstances ; and as there is at present nothing to be added to the general account alread}'
given of the structure and life-history of the sarcode-bodies of the Foraminifera, our attention
will be now directed to the characters furnished by the investments which they form, with a
view to determine what are those on which the primary and secondary subdivisions of the
group may be most satisfactorily based.

57. Texture of the Skell. — In the shells of Foraminifera, as was correctly pointed out by
Prof. Williamson (ex, p. xi), three very distinct varieties of texture are easily recognisable :
the porcellanous, Xhe hyaline or vitreous, and the arenaceous. — In the first of these varieties the
shell, when viewed by reflected light, presents an opaque-white aspect, which bears a strong
resemblance to that of porcelain, especially when (as in Penerojjiis) its surface is highly
polished. When thin natural or artificial laminae of it, however, are viewed with transmitted
light, the opacity gives place to a rich brown or amber -colour, which seems to be imparted
by the animal matter that is united with the calcifying deposit, the colour of the sarcode-body
being usually the same as that of the shell. In a few instances both the shell and the animal
body have a rich crimson hue. No structure of any kind can be detected in this kind of
shell-substance, which is apparently homogeneous throughout. When shells of this character
are decalcified by dilute acid, a delicate, gelatinous-looking substratum of animal matter is
left, very distinct in its aspect from the sarcode-body which the shell included (Plate IV, fig. 14).
This, in fact, seems to bear the same relation to the protoplasmic substance, that the cellulose
wall of the vegetable cell bears to the " endoplast" from the surface of which it is excreted ;
and just as in Biatomacece the consolidation of that exudation by silex forms the beautiful lorica
characteristic of that group, so here does the consolidation of an analogous excretion-layer by

alcareous deposit form the shellv wall of each segment of the animal. Although the shells
of the porcellanous type often present the aooearance of bemg perforated with foramina, yet
this appearance is illusory, being due to a mere " pitting" of the external surface, which pitting

PRINCIPLES OF CLASSIFICATION. 45

though often very deep, never extends through the whole thickness of the shell. Some kind
of inequality of that surface, indeed, is extremely common in the shells of the porcellanous
Foraminifera. Very frequently it presents an alternation of ridges and furrows, such as dis-
tinguishes certain varieties o^MilioJa (Plate VI, figs. 3, 4) ; and this alternation is so regular and
constant in Prawo/V/s (Plate VII, fig. 18), and in the first-formed segments of Vertebralina
(Plate V, figs. 17 — 25), as to be peculiarly characteristic of those types. In other instances,
especially among the Miliohc, we find the surface marked by depressions which may vary
greatly in size and in arrangement (Plate VI, figs. 13, 14), being sometimes minute puncta-
tions, in other cases being lai'ge areolae ; being sometimes scattered with no apparent regularity,
in other instances disposed with the most exact symmetry. But no difference of texture
accompanies any of these inequalities of the surface, the raised and depressed portions being
alike homogeneous.

58. In the shells of the vitreous or hyaline type, on the other hand, the proper shell-
substance has an almost glassy transparency ; which is shown by it alike in the thin natural
laminas of young specimens, and in artificially-prepared sections of such as are thicker and
older. It is usually colourless, even when (as is often the case with Rotalia) the substance
of the animal is deeply coloured. In certain aberrant forms of the Rotaline type,
however, we shall see that the shell is commonly, like the animal body, of a rich crimson hue.
But notwithstanding the transparence of their substance, these shells derive an adventitious
opacity from being channeled out more or less minutely by tubular perforations, which, when
occupied either by air or by any substance having a refractive power different from that of
the surrounding shell, interfere with its power of transmitting light, and cause it to reflect a
large part of that which falls upon it. Their effect varies, however, according to their degree
of minuteness and the closeness of their arrangement. Thus, in Rotalia, in which they are
commonly almost 1 -3000th of an inch in diameter and somewhat more than that apart
from one another (Plate XIII, fig. 1, a), the hyaline transparence of the thin shell makes
itself apparent between them, and imparts to its entire surface a vitreous aspect.
In Opercidina and Cycloclypem, on the other hand, in which the average diameter of
the tubuli does not exceed l-10,000th of an inch, and their distance from each other is
not much greater, every part of the shell that is traversed by them presents a semi-
opacity, which only disappears when extremely thin sections are made in a direction
exactly transverse to the axis of the tubes, so as to enable the transparence of the intervening
substance to display itself without interruption (Plate XIX, fig. 4). It often happens, how-
ever, that certain parts of the shell are left unchanneled by these tubuli ; and such are at once
distinguished, even under a low magnifying power, by the readiness with which they allow
transmitted light to pass through them (Plate XVII, figs. 12, 13, aa, da, U\ and by the peculiar
vitreous lustre they exhibit when light is made to fall obliquely upon their surface. In shells
formed upon this type we frequently find that the surface presents either bands or spots which
are thus distinguished ; the non-tubular bands usually marking the positions of the septa (Plate
XVII, fig. 1), and being sometimes raised into ridges, though in other instances they are either
level or somewhat depressed, whilst the non-tubular spots may occur on any part of the
surface, and are most commonly raised into tubercles (Plate XV, fig. 5, and Plate XIX, fig. 5),
which sometimes attain a size and number sufficient to give a very distinctive character to the

46 OF THE FORAMINIFERA GENERALLY:

shells that bear them. In shells of this type, however, which have been long dead and exposed
to the action of sea- water, the vitreous transparence often gives place to a lustrous white
opacity, that is particularly striking in the prominent tubercles ; as is remarkably shown in the
tuberculated variety of Plamrhdina vulgaris (Plate XIII, fig. 1 5) . The texture of the shells of
this type is much firmer tl;an that of the porcellanous shells ; approaching closely to that of the
inferior forms of dentine, or to that of the terminal portion of the crab's claw.

59. Between the comparatively large apertures which are common in the Rotaline type,
and the minute tubuli of the OpcrcnVine, there is such a continuous gradation as indicates that
their mode of formation, and probably their uses, are essentially the same. In the former it
has been demonstrated by actual observation that they allow the passage of pseudopodial
extensions of the sarcode-body through every part of the external wall of the chambers
occupied by it ; and there is nothing to oppose the idea that they answer the same purpose
in the latter, since, minute as they are, their diameter is not too small to enable them to be
traversed by the finest of the threads into which the branching pseudopodia of Foraminifera
are known to subdivide themselves. And it seems the more likely that they answer this
purpose, when attention is given to the remarkable continuity which they exhibit through a
considerable thickness of shell, formed of numerous lamellffi that seem to have been added at
successive periods of growth (Plate XIX, fig. 3). Now, if this be the case, it is not difficult to
account for the production of a texture closely resembling that of dentine, without having
recourse to the hypothesis (xxv, p. 421) of a higher organization in the bodies of
these animals than that which we have other grounds for admitting. For if the
shell-substance be, as there seems reason to believe, an excretion from the |3rotoplasmic
mass of which the body itself is composed, each new lamella, as it is added to the pre-
ceding, will mould itself upon the pseudopodia that issue from the orifices of the subjacent
surface ; either some difference in their composition, or the activity of the changes con-
tinually taking place in their substance (^ 34), preventing them from being involved
in the consolidation which takes place ai'ound them. We have an illustration of the same
kind on a larger scale, in the extension of the straight branches of the canal-system which
pass through the solid masses of shell-substance that occupy the umbilical regions in the shells
of Calcdrina and Fohjdomella (Plate XIV, fig. 3, and Plate XYI, fig. 3) ; the successive accretions
of vitreous material being so disposed around the extensions of the sarcode-body which occupy
these passages, as to preserve their continuity throughout, and thus to maintain the most
direct relation between the parts of the canal-system most deeply buried beneath these accre-
tions, and the external surface from which they become further and further removed. If this
should prove to be the true account of the formation of the dentine-like tissue produced by
the higher type of Foraminifera, it will deserve consideration whether a like explanation may
not be applicable to the formation of analogous calcified tubular tissues in animals much more
elevated in the scale ; especially since there is increasing reason to believe that the develop-
ment of such tissues takes place after a far simpler fashion than has been commonly
supposed, and that their foundation is laid in a homogeneous blastema, rather than in a
matrix possessing distinct organization.

60. Besides these two principal types of shell-structure, another is met with in certain
groups of Foraminifera, which is designated as the arenaceous; the shells being formed, either

PRINCIPLES OF CLASSIFICATION. 47

partially or wholly, not of a calcareous exudation from the sarcode-body, but of particles of
sand obtained from without, the cement with which they are attached together being all that
is furnished by the animal. The aspect of such " arenaceous " shells necessarily varies con-
siderably with the kind of material of which they are composed ; and the same t3'pe, inhabiting
several different localities, may thus present as many diverse fades. Thus, the TextularicB
dredged off the Canary Islands have their shells entirely composed of fine particles of a
black sand, apparently formed by the disintegration of volcanic rocks ; whilst those of the
Red Sea have shells of a grayish-yellow colour, the arenaceous particles of which vary much
more in their nature and origin. In some instances the particles are very uniform in size,
and are very methodically disposed (like those of which the tube of Pectinaria is made up) ;
so that the surface of the shell has almost the appearance, when sufficiently magnified, of a
tesselated pavement (Plate VI, fig. 41). This regularity — alike in size, form, and arrangement,
— is sometimes so remarkable as to have given rise to the supposition that the siliceous par-
ticles are not derived from external sources, but are formed by exudation from the surface of
the contained body. As, however, there is no siliceous " test " at present known to be formed
by an animal of this group, which is not obviously made up of an aggregation of distinct parti-
cles, instead of possessing the structural homogeneousness proper to the shells which are
undoubtedly formed by calcareous or siliceous consolidation, it would probably be correct to
say that the true " shell " of Foraiidnifera is imiformly calcareous, and that when this is
replaced by a siliceous " test " the materials of such test have been drawn together from
external sources. There are certain cases, on the other hand, in which the sandy paiticles
are less uniform in size and less regular in disposition, and are imbedded in a calcareous
cement which forms the essential constituent of the shell ; in these the arenaceous texture,
being superficial only, and to a certain extent accidental, has not that importance as a differ-
ential character which it bears when extending throughout the thickness of the shell.*

* The surface of certain Foramiuiferous shells (especially Globigerince) is not unfrequentlj'
studded with the minute rounded or oval bodies to which the name " coccolitlis " was first given by
Professor Huxley. (See his Appendix to the ' Report on Deep-Sea Soundings in the North Atlantic
Ocean, between Ireland and Newfoundland, made in H.M. " Cyclops," Lieut. -Com. Dayman, in June
and July, 1857.") These bodies have been since observed by Dr. Wallich (civ b), not only in the free
state, but adherent to the siu-face of minute spherical cells which seem to constitute a rudimentary
type of Foraminifera ; the uniformity of this adhesion being such as to lead almost necessarily
to the conclusion that it is a normal condition. These " coccoliths " are described by Dr. Wallich
as of an oblong form, concave on their internal aspect, and convex externally (Fig. I, s, i), their
average length being about l-3700th of an inch ; in some specimens there is but a single aperture in the
centre ; in others the aperture is double, the two portions being separated by a
delicate transverse band; and the external marginal surface, which constitutes a ■''"'• ^•

quoit-like oblong ring round the central perforated portion, is marked with radi- '•^^*;

ating striae. The spheres, to the surface of which the coccoliths are found adherent %^ \
at nearly regular intervals, are stated by Dr. Wallich to have a diameter from l-1.250th ale

to l-1600th of an inch, and to be composed of a sarcode-like substance enclosed W ^ y V5>s^
in a dehcate limitary wall, apparently consolidated by calcareous deposit (Fig. I, 1, 2, Cocoosplieres ;
1, 2). These bodies, to which he has given the name of " coccospheres," are 3, Jr, CoccoUtlis.

48 OF THE FORAMINIFERA GENERALLY:

61. To separate all the Foraminifera that form "arenaceous" shells from tliose of the
" porcellanous " and " hyaline " t3'pes, to which many of them obviously bear the closest
affinity, would be a violation of the first principles of a natural arrangement ; and yet we
shall find that there are certain generic types in which the sandy texture is a character of
great systematic importance. Thus, on the one hand, in the low " porcellanous " type Nuhc-
cularia, and in the "triloculine" and " quinqueloculine" forms of the more elevated type Miliola,
individuals frequently present themselves whose surface is rendered arenaceous by the im-
bedding of sandy particles in their ordinary calcareous shell-substance ; but for being thug
" rough-cast," such individuals would present the ordinar}' aspect of their i-espective types, to
which they are entirely conformable in every other character ; and it would be manifestly
improper to rank them apart on account of this trifling variation. So even when we find
truly arenaceous shells presenting the characteristic forms of the " hyaline " genera BuUmina
and Textularia, since we find at the same time that not only do they correspond in general
structure to the calcareous shells respectively peculiar to those genera, but are perforated like
them by regular pores for the passage of pseudopodia, we feel that we have no right to dis-
sociate what are manifestly nothing else than varieties of a common type. But when, on
the other hand, we find that certain assemblages of forms, constituting well-marked generic
types, can be uniformly characterised by the possession of "arenaceous" shells, — as is the
case with Trochammina, ValviiUna, and Liiuola, — it becomes obvious that this peculiarity is to
be regarded as a distinctive feature of higher value, since it marks a fixed and decided phy-
siological condition, the occurrence of which elsewhere is only occasional or incomplete. The
absence of any pseudopodial pores in the walls of the chambers of the shells of this group shows
their affinity to be rather with the porcellanous than with the hyaline series, notwithstanding
the very close resemblance in form which some of them present to particular types of the
latter, — Valvulina, for example, to BuUmina, certain Lifuola to Nonionina, and TrocJiammina
to SpirU/ina.

62. Turning now from the ultimate texture of the shell to its conformation, we have to
inquire whether there are any fundamental and essential diversities in its mode of increase,
which can be advantageously used as difl'erential characters. It may be stated as an un-
questionable fact, that the shelly casing, once formed to any portion of the sarcode-body, cannot
be enlarged by interstitial growth ; and hence it can only be adapted to the augmenting
dimensions of that body, by addition to the part already formed. In the greater part of the

Fig. II.

sometimes united in series, after the manner of certain forms of

Foraminifera ; thus in Fig. II, i, is shown a Nodosarian series of four

equal cells ; whilst at ;; is seen a Textularian series of seven cells,

which increase regularly in diameter from l-1350th to l-450th of an inch.

The " coccoliths " do not appear to be attached to the wall of the " cocco-

sphere" in any other way than by gelatinous adhesion ; and hence they

are very easily detached, so as to form a considerable proportion of

Coccosphcies, with attached m^ny deep-sea deposits. Similar bodies have been found in Chalk by Mr.

coccoliths, growins; (1) on

the Nodosarian, (2) on the ^" ^°''^y-

Textularian type.

PRINCIPLES OF CLASSIFICATION.

49

" nioiiollialamoiis " I'oramiuifera, the contraction of the aijerture entirely forbids the enlarge-
ment of the ca\ity by any sucli addition, but those spiral forms in which there is no such
contraction are capable, like t!ie tubular shells of Annelids and certain Mollusks, of bcin"-
indclinitely extended ; and it is simply because of its absence, that they present no indication
of the segmental division which would otherwise be marked by a transverse septum every time
that a longitudinal addition is made. This is the case with the genera Cormcsjjmi, Trochammina,
and SpirilUiiri, which arc respectively the porcellanous, arenaceous, and hyaline representa-
tives of the simply spiral plan of conformation ; and it is obvious that, although structurally
" monothalamous,'' these genera are in reality more nearly allied in their capability of
unlimited growth to the " polythalamous" series. The " polythalamous" shells are formed, as
already explained, by the repeated gemmation of the sarcode-body ; and it usually (though
by no means constantly) happens that the successive gennnaj increase in size, so that each
chamber is larger than the one which preceded it. The simplest types of Pohjthalntnki arc
those in which the segments of the shell have only an external adhesion, the cavities of their
chambers having no communication with each other ; as is the case in the im^jcrforatc series
with Daciz/Jopora and Aclcidaria, and in \\\q perforated with Glob'igerina. Save in these types,
however, the cavity of each segment always communicates with that of the segment from
which it is budded off ; and this it may do merely by the apertural neck of the older segment,
which dilates into the globular cavity of the newer, so that the succession of segments is
united into the semblance of a string of beads, as we see in some forms of Nodo>iaria (Plate
XII, fig. 2). More generally, however, the apertural portion of one segment is completely
embraced by the walls of the next chamber, in the manner diagrammatically represented in
Fig. Ill, where the primordial chamber is seen at 0 and its aperture at n ; this aperture is
received into the second chamber, 1, the lateral
wall of which joins the anterior wall of the preced-
ing at h ; in like manner, the aperture «^ of the
second chamber is received into the third chamber

2, the aperture of this, «°, into the next chamber

3, and so on, the aperture n"^ of the last chamber
opening externally. — A great alteration in external
shape may be produced, without any departure from
the rectilineal plan of growth, by the still more com-
plete reception of the anterior portion of the older
chamber into the posterior portion of the newer; as
is shown in Fig. IV, wliich diagrammatically repre-
sents the " frondicularian" form of Nodosarina. —
On the other hand, a complete alteration in external configuration may be pioduced by the
substitution of a curviliiirar for a reclilliiear axis of growth ; the most ordinary type of the
former being a spiral, which may be either flat, like that of a Nm/tilns, or may coil around a
longitudinal axis, like that of a Trocluis. Between the rectilineal and the spiral forms of axes
of growth a complete gradation is presented in the Nodosarine series. In Fig. VII we see
that the relations of the chambers may be essentially the same in the spiral as in the recti-
lineal type ; the septal plane that divides each chamber from its successor being formed
solely by the anterior wall of tlie older, which serves as the posterior wall of the newer.

Fig. III.

Fig. IV.

50

OF THE FORAMINIl'ERA GENERALLY,

This is the case tiiroughout the 'porcellanom series and with the lower forms of the vitreous
series. But in the highest types of the latter we find that each chamber of the spire has a

Fig. V

Fig. VI

Fig. VIII.

complete shelly envelope of its own, the new segment forming a posterior wall, which
applies itself to the anterior wall of the preceding segment, so that each septal plane
(except that of the last chamber) is composed of two lamella;, as is shown in Fig. VIII.
— The same difference exists among the Polt/tlialauiia formed upon the cijdkal plan of growth,
which is ordinarily the result of the gemmation of the primordial segment not on one side
only, but from every part of its circumference, and the subsequent repetition of the same
mode of increase (see Fig. XXIV, p. 108). For in the cyclical forms of the porcelhnio/'s series
the successive annuli are joined, each to its predecessor, in such a manner that the external
wall of the latter serves as the internal wall of the former, as is seen along the lines a a, a a,
Fip-. V; and the septa dividing the adjacent chamberlets of the same annuli are also single.
In the cyclical forms of the vifreo//s series, on the other hand, each chambcrlet has its own
proper wall, as is shown in Fig. VI : so that not merely the annular but the radial septa are
all double.

63. But this is by no means all ; for in the higher types of the hyaline or vitreous series
we frequently meet with an " intermediate" or " supplemental" skeleton, formed by a secondary
or exogenous deposit upon the outer walls of the chambers, by which they receive a great
accession of strength. This deposit not only fills up what w^ould otherwise be superficial
hollows at the junctions of the chambers, or (as in PolydomeUa) at the umbilical depression,
but often forms a layer of considerable thickness over the whole surface, thus separating
each whorl from that which encloses it (Fig. YIII, d) ; and it is .sometimes prolonged into
outo-rowths that give a very peculiar variety to the ordinary contour, as in some varieties
of Botalia and FohjstomeUa, but most characteristically in Calcanna (Plate XIV, figs. 1, 2, 8)
and the stellate form of Tinopori's (Plate XV, figs. 5—9). This intermediate or supplemental
skeleton, wherever developed to any considerable extent, is traversed by a set of "canals,"
which are usually arranged upon a systematic plan, and are sometimes distributed with
considerable minuteness. The passages which make up this " system" are not true vessels, but
are mere sinuses, left in some cases by the incomplete adhesion of the two contiguous walls
which separate the adjacent chambers, and in other cases apparently originating in the
incomplete calcification of the sarcode which forms the basis of the solid skeleton ; certain

PRINCIPLES OF CLASSIFICATION. 51

portions of that substance remaining in their original condition, so as to maintain a communica-
tion between the contents of the chambers and the parts of the calcareous skeleton most
removed from them, analogous to that which the Haversian canals afford in the case of latninte of
bone not in the immediate vicinity of a vascular surface. As, therefore, the development of the
Haversian system is related to the thickness of the bone-substance to be nourished, so does that
of the canal-system in Foraminifera seem to be related to the amount of the consolidating
substance which constitutes the supplemental skeleton. There is good reason to believe that
these canals are occupied in the living state by prolongations of the sarcode-body, which pass
from the chambers into the portions of the system in nearest relation to them, and proceed to
its peripheral extensions ; and they are largest and most numerous where nutriment has thus
to be conveyed to parts of the supplemental skeleton, which (like the outgrowths of Calcarina)
are very far removed from the segments of the ordinary sarcode-body. Now, although it is
only in the largest and most developed types of the hyaline series, that we meet cither with a
distinct " canal-system" or witli any considerable amount of that intermediate deposit which
it nourishes, yet the jDresence of these two peculiar features most strongly differentiates those
types from such of the porcellanous series as most nearly resemble tliem in general plan of
growth, and to which, according to any classification essentially founded on that character,
they would be most nearly approximated, — as, for example, the hyaline Ojjerculina from the
porcellanous Pciieroplls, the hyaline Cydodypeas from the porcellanous Orbitolites.

64. Another strongly marked difference, that seems no less obviously related to the
physiological condition of the animal than the perforation or non-perforation of the shell, is
observable in the degree of separation that exists between the segments of the sarcode-body
in the two series respectively ; this body even in the most complex types of the imperforate
shells being an aggregate of mutually related parts, whilst even in the simplest types of
the perforated these parts acquire a much higher degree of independence, so as to live much
more /';/• and by themselves alone. The key to this difference is furnished by the relative
size of the aperture, which indicates in the unilocular types the degree of readiness with
which the animal can extend itself into the medium it inhabits, whilst in the raultilocular it
indicates not only this, but also the relative amount of connection between the several segments
of the composite structure. Thus, when we compare the unilocular Gromia (which, though
possessing only a membranous " test," may be considered as physiologically representing the
unilocular type of the imperforate Foraminifera) with the unilocular Layena, we are at
once struck with the extreme narrowness of the aperture of the latter, as compared with
the wide, open mouth of the former (Plate II, fig. 2) ; and this difi'erence will be readily
understood, when it is borne in mind that in one case the principal aperture is supple-
mented (so to speak) by the' pores distributed through the whole of the globular casing that
encloses the body of the animal, every one of which allows the passage of a pseudopodium,
whilst in the other the sarcode-body, shut up within its " test," has no other means of com-
munication with the external world than that afforded by its single orifice. So, if we compare
the apertures of Niibecularia, Vertebralina, and Miliola with those of the Nodosarian series, we
find a no less striking contrast between the mere constrictions that mark out the segmentation
of the sarcode-body in the former, and the almost complete separation that exists between the
successive chambers in the latter. In Pmeroplis, again, although the apertural pores are

52 OF THE FORAMINIFERA GENERALLY:

individually small (Plate VII, fig. 18), yet their multiplication (which takes place proportionally
to the size of the chambers) renders the aggregate communication very free, as we see in the
deiidriftue variety, in which the pores are all gathered together, as it were, into one aperture
(Plate VII, fig. 1 ) ; and the contrast is very marked between the large si^e of this, and the extreme
narrowness of the fissure which forms the only constant communication between the chambers
of OpercuJina. The like contrast, in regard to the connection of the successive segments, exists
between Orbiculina, the spiral type of which may be described as a Pnirroplis whose principal
chambers are partially subdivided by transverse partitions, and Hcferosfet/ina, which bears the
like relation to Operciilina. And a no less striking difference exists, in this respect, between
Orbitolites, which is the most developed type of the imperforate series, and Ci/e/oc/ypei/s, which
holds a like position in the perforated ; the communications between the successive annuli in the
former, and between the outermost annulus and the exterior, being so numerous and free, as to
amount in the aggregate to a large apertural area, whilst in the latter they are so much more
restricted as to be not readily discoverable. This tendency to a more complete separation of
the segments sliows itself yet more strongly in regard to the transverse subdivision of the
principal chambers in Orbiculuia as compared witli Ili'tcroxti'gina, and in Orbitolite-s as com-
pared with Cydoclypeus ; for in the two imperforate types we find this transverse subdivision so
far from complete, that it resembles that of a long dormitory in which the beds (arranged in

rows on the two sides) are separated from each other by partitions
that extend from the walls towards the central line of the apart-
ment, but stop short of it, so as to leave a free passage from one
end of it to the other ; whilst in the two perforated types the
chamberlets of each row are entirely cut off from each other
laterally, communicating only with those of the rows behind and in front of them. Thus
we see that, whereas in the imperforate shells the nutrition of the entire body is
derived from the alimentary materials obtained l)y the last segment alone, every segment
in the perforated shells is capable of obtaining, at an}' rate, a portion of its supply for itself;
and hence a much greater degree of individualization of the segments is possible in the
latter case than in the former. We shall find tiiis contrast most strongly marked when
we come to compare the calcareous skeleton of OrbifoNfe-s- with that of Cydoclypeus ; the
former being, as it were, a concretionary framework, which grows up in the midst of and around
the sarcode-body for its support and protection, isolating its parts from each other no more than
is required for that purpose ; whilst in the latter each segment and sub-segment has its own
distinct and complete envelope, which seems (as it were) to be moulded upon its shape, any
interspaces being filled in by the intermediate skeleton, whose intervention between the two
layers of the double partitions renders the isolation of the chambers yet more complete.

65. Thus, then, we find that, alike in the intimate structure of the shell, in the presence
or absence of an " intermediate skeleton" and of a " canal-system" for its nutrition, in the com-
pleteness witli which each chamber is surrounded by its own proper wall, and in the degree
of its separation from adjacent chambers — all which features are as characteristic of every
individual portion of the shell as they are of the shell as a whole, and are evidently in intimate
relation with the physiological condition of the animal that inhabits it, — a very decided
differentiation may be established between the two series of imperforate and perforated

PRINCIPLES OF CLASSIFICATION. 53

FoRAMiNiFERA ; and this primary differentiation will be found so constantly to harmonize
with the grouping which would be based on the principle of continuity of gradation, that I
cannot entertain a doubt of its being the one on which (in our present state of ignorance
respecting the physiology of this tribe) our classification may be most securely based. For it
will be found that the several types of " porcellanous" Foraminifera, however diversified in
form, constitute a series connected throughout by the closest links of mutual affinity ; whilst
the proper " arenaceous" types form a parallel series, of which the members are not less
closely related to each other. In like manner we shall find that the far more numerous
forms of the " hyaline" Foraminifera may be ranked together into a small number of assem-
blages, the members of each of which are so gradationally united that the groups thus composed
are obviously in the highest degree natural ; whilst these series are at the same time connected
with each other, not only by their mutual approximation to certain fundamental types, but also
by intermediate forms which serve to link together even their more divergent portions, the
whole being thus united into a compact aggregate, of which there is no part that is not held
{as it were) to the rest by firmly cohesive attraction. — -It must not, however, be supposed that
every member of the one series is differentiated by the characters just enumerated from everv
member of the other. The non-perforation of the walls of the chambers, the singleness of
the septal partitions, and the freedom of the apertural communications between the chambers,
seem invariably to characterize the shells of the porcellanous type ; whilst the perforation of
the walls of the chambers, the duplication of the septal partitions, and the straitness of the
apertural communications, appear to be no less constant characteristics of the shells of the
hyaline type. The "intermediate" or "supplemental" skeleton, on the other hand, presents
itself to an extent that makes it readily distinguishable, only in the most developed forms of
the hyaline series ; and it is not a little remarkable that within the limits of one and the same
generic type {T/iio/joi7/s) we meet with certain forms in which this portion of the fabric is evolved
to an extraordinar)^ degree, whilst in others its presence is not to be traced at all. And the
same may be said of the " canal-system," which presents its most extensive and symmetrical
distribution in the highest examples of certain generic types, whose less elevated specimens show
scarcely any traces of it. Hence, whilst the presence of an "intermediate skeleton'' and of a
" canal-system" in one Foraminiferous shell serves to mark it as belonging to the higher section of
the hyaline series, their absence in another must not be regarded as indicating its porcellanous
characters, seeing that such absence prevails equally through the lower section of the hyaline
series also. And it is chiefly because their presence, in connection with other characters, serves
to mark a /iis/f>i or tendency in the one series, of which no trace whatever is presented by the
other, that it has been here included among the features of distinction between the two.

66. On the other hand, there is an entire absence of any other special relation between
the members of the " porcellanous " and those of the " hyaline " series, than that which
arises out of the configuration of their respective shells ; which configuration is determined b_v
their plans of (jrowtli, that is, by the direction in which new chambers are successively added.
Thus, in both series we have rectihneal, spiral, cyclical, and acervuline forms, with everv
gradation between these ; and it is true that such a striking isouiorpliisiii. displays itself between
certain types of these two series respectively, as would not unnaturally lead any svstematist
whose views of classification of Foraminifera might be founded on their supposed Molluscous

54 OF THE FORAMINIFERA GENERALLY:

affinities to a belief in their mutual affinity. A most complete isomorphism presents itself,
for example, in the simple spiral which constitutes one of the lowest forms of the porcellanous,
the arenaceous, and the hyaline series respectively ; and by such as have not traced out the
affinities of this spiral in each series, it might readily be supposed that such a conformity in
the plan of growth of the shell must be indicative of conformity in the physiological condition
of the animal.* But the porcellanous Cornuspira and the hyaline Spirillina differ not merely
in the texture of their shells, but in what we have seen to be the fundamental character of
non-perforation in the one and perforation in the other ; and whilst the former graduates
almost continuously into the spiroloculine form of Miliola, the latter is in like manner related
to Botalia through the vermiculate varieties of the latter genus. So the arenaceous, simply
spiral Trocliammina, which agrees with Conimpira in its non-perforation, not only differs from
it in the almost purely arenaceous composition of the shell, but also in the varietal forms into
which it passes ; and by some of these it is brought into relation with the other types of the are-
naceous series. — Passing now to the higher forms, we meet with so remarkable an isomorphism
between the nautiloid forms of Peneroplis and Operculina (the septa of the latter genus, besides
their regular aperture at the inner margin, being perforated here and there by secondary pores
that remind us of the former), between the subdivided spirals of Orbiculiiia and Heterostc^ina,
and between the discoidal OrbitoUtes and Cydoclyiwus, that, in any classification founded mainly
upon plan of growth, the genera of each pair must be placed in near proximity to each other ;
yet they are really separated by all those characters which have been shown to possess the
highest physiological value, and can only be regarded as " representing " each other in the
series to which they respectively belong. A like " representation '' will be shown to exist
among the higher forms of the arenaceous series ; certain varieties of Lituola, for example,
bearing a close resemblance to Nonionina, and others to the spiroline variety of Peneroplis ,•
whilst ValvuJina may take on the forms of Ttotalia, BuUuiina, and other hyaline Foraminifera.

67. It seems obvious, from the foregoing considerations, that the importance of plan of
growth, as a character available in the classification of Foraminifera, is far below tliat of the
aggregate of other characters which stand in more intimate relation to the physiological con-
dition of the animal ; and the low value which ought to be attached to it is further indicated
by its frequent tendency to variation within the limits of what are shown by the evidence of
gradational affinity to be well-marked natural groups. Such a tendency seems greatest in
the lower types of each series ; " polymorphism " being the rule among them, rather than the
exception. Thus we shall find that Niibecularia, one of the simplest of the porcellanous
Foraminifera, presents itself under such a variety of forms, that the attempt to classify these
in any system based on the geometrical arrangement of the successive segments, would
lead to nothing but a most absurd separation of what are clearly but varietal modifications of
one and the same type. In Vertebralina we find, with a closer general conformity to a
common type, a range of variation which is still very remarkable ; and even when we rise as

* Thus, by Professor Scliultze (xcvii, pp. 40, 41), the porcellanous and the hyaline spirals have been
ranked as Cornuspira jjlanorbis and C. perforata ; whilst by Prof. Williamson (cs, pp. 92, 93), the
porcellanous, arenaceous, and hyaline spirals are designated respectively Spirillina foliacea, S. arenacea,
and S, perforata.

PRINCIPLES OF CLASSIFICATION. 55

high as Peneroplis, we very commonly observe a change in the direction of growth from the
spiral to the rectilineal with the advance of life. The spiral growth of OrbicuUna, again,
often gives place to a cyclical plan exactly resembling that which is typical of Orbitolitcs ;
whilst at the commencement of the development of Orbitolites, which is typically cyclical, the
chambers are sometimes added according to a spiral arrangement. In the same manner, when
we enter upon the " hyaline" series, we shall find ourselves compelled by the like continuity
of affinities to rank as varietal modifications of the single generic type Nodosaria a long list
of reputed genera, separated by D'Orbigny under his three orders, Sfichostet/ues, Helicoste^ues,
and Enallosteyues : and marked changes in the plan of growth frequently present themselves
among the higher genera of that series in the life of one and the same individual ; the early
arrangement of the chambers of PlanorbuJina and Tinoporm, for example, being as typically
spiral as that which prevails in Bofalia, but flie additions being subsequently made in such a
manner as to convert the spiral, in the first instance, into a circular disk, which may then
increase at its periphery so irregularl}' that all definiteness of contour vanishes, whilst the
chambers may also be piled one upon another in an irregular " acei'vuline" manner, so as
entirely to mask either their original spiral or their secondary cyclical arrangement.

68. The foregoing examples serve to show, not only that neither plan of t/rowth nor
remdtant form can be rightly taken as a character for sepai-ating the great primary divisions
of FoRAMiNiFERA, but also that they are so often liable to variation within the limits
of genera, that no constant reliance can be placed on them as means of difl'erentiating even
these subordinate groups from each other. It will be usually found much safer, in fact, to
place our chief reliance on those characters which can be stated in terms of each individual
segment, than on those which can only be predicated of the aggregate. And no characters
are, in general, so free from the fallacy resulting from tendency to variation, as those which
are drawn from the nature and position of the septal apertures. Even these, however, in
certain exceptional cases, share in the general tendency to variation ; and in estimating the
value which should be attached to such diversities, it is important to bear in mind the remark
already made (p. 8) as to the purpose which is served by these apertures. It must obviously
be a matter of no great physiological importance, whether a number of those fine threads of
sarcode, which act as stolons connecting the successive segments of the body, and are put
forth as pseudopodia from the last, pass out in one undivided bundle, or be separated by the
interposition of minute pi'ocesses of shell, which convert a narrow fissure into a row of pores,
or a wide orifice into a cribriform plate. Such a difference exists between the aperture of
Rotalia and that of Calcarina, and between that of Miliola and that of Haucrina ; and it could
not be regarded as even of sub-generic value in those two cases, if it were not accompanied
by other distinctions. A far greater dissimilarity exists between the aperture of Feneroplis
and that of Bendritina, the former consisting of a linear series of separate pores, whilst the
latter is a single, large, dendritic orifice : and yet, as I have elsewhere shown (xv), the former
of these conditions graduates into the latter so continuously as to render it impossible to draw
any definite line of demarcation between them ; and each is related to the shape of the septal
plane, which may vary no less gradationally from that of a long, narrow band (Plate VII,
fig. 16, ff), to a cordate or sagittate form (figs. 6, a, 14, h, c), according to the compression or
turgidity of the spire. Hence, as there is a most remarkable accordance between these two

56 OF THE FORAMINIFERA GENERALLY:

types in all other respects, and their dififerences are such as occasionally present themselves
to a certain degree between the successively formed portions of one and the same organism,
they cannot be generically separated ; and, notwithstanding the extraordinary contrast
presented by their extreme forms, both in the shape of their septal plane and in that of their
aperture, the one must be regarded as merely a varietal modification of the other.

69. Since, then, even the characters which in some groups of Foraminifera are most
stable, are in others so inconstant as to be quite valueless for the purposes of the systematist,
the inquiry naturally arises whether any definite method of generic and specific differentiation
can be laid down; and to this inquiry I have to answer — not for myself alone, but for Messrs.
Parker and Rupert Jones, whose views on this point are in complete harmony with my own —
that in the present state of our knowledge such a methodization is impossible. Whether it will
ever be practicable to arrange the multitudinous forms of this group in natural assemblages
whose boundaries shall be capable of strict limitation, is to us by no means, certain ; since the
tendency of every extension of our researches is to enlarge our idea of the range through which
these forms may vary. And all that it seems to us at present feasible to attempt, is to group them
around certain generic types, each marked by some combination of characters which impresses
on it (so to speak) a distinctive physiognomy, and to trace out the principal modifications to
which these types are subject through the separate or combined variation of their characters.
Among these modifications there will generally be found some which indicate an afiinity towards
other types, so as to diminish the intervals between each type and those to which it is related.
Wherever such a gradation can be shown to exist with anything like complete continuity, its
presence will be accounted a suSicient reason for including the whole series (however
diversified in its extreme forms) under one and the same generic designation ; where, again, it
seems likely to be established by further research (which is sometimes especially the case in
regard to extinct types), the modification thus related will be ranked as a suh-c/enus ; while the
existence of such a decided break between any two types, as enables any specimen at present
known to be referred without hesitation (after a sufficient examination of its structure and
affinities) to one or to the other, will be held to justify their //ww/e separation.

70. The impracticability of applying the ordinary method of definition to the (/encra of
Foraminifera becomes an absolute impossibility in regard to species. For whether or not
there really exist in this group generic assemblages capable of being strictly limited by well-
marked boundaries, it may be affirmed with certainty that among the forms of which such
assemblages are composed, it is the exception, not the rule, to find one which is so isolated
from the rest by any constant and definite peculiarity, as to have the least claim to rank as a
nalaral species. Nothing is more easy, however, than to make artijiciaJ species in this group ;
for the variation to which every one of its generic forms is liable, gives rise to a multitude of
dissimilar forms most inviting to those systematists who consider that credit is to be gained
by adding new names to the already enormous list; and accordingly we find that a vast mass
of such specific names and definitions has been accumulated, of which but a very few really
express the facts they are designed to record. For it is the habit of such systematists
to pick out only what they consider the well-characterized types, and to disregard the inter-
mediate or osculant forms that establish the gradation between these, neglecting altogether

PRINCIPLES OF CLASSIFICATION.

57

the fact that the existence of such a gradational series entirely does away with the fundamental
assumption on which tlie idea of a natural species (as ordinarily understood) is based. When
a large collection of individuals of one generic type is brought together (such as that placed
in my hands by Mr. Gumming of the Opcrmlina of the Philippine Seas), it very commonly
happens that by selecting the most divergent forms, a considerable number of specific types —
say six, eight, twelve, or even twenty — might be readily establislicd, and a considerable part of
the collection might be arranged around these as centres ; but after all the specimens have
being thus separated, which present a sufSciently close conformity to those types to admit of
been referred to one or other of them without hesitation, there will remain a considerable
proportion in which the characters of two or more are combined with such equality as to
render it impossible to assign to them any other than an intermediate position, whilst there
will be others which present such departures from any of them as themselves to have an
equal claim to rank as distinct species ; so that there is no middle course between that
of grouping the whole series as varieties of one species, and that of erecting into a distinct
species every varietal modification presented by individuals, — a course which would be the
■reductio ad absurdum of the ordinary system of species-making in its application to this group.

71. Two sets of characters may be especially named, on which it has been customary to
found specific distinctions ; these are the form of the septal plane, and external sculpture or
stirface-markini/. Now, in regard to the first of these, it may be affirmed most positively
that wherever any marked variation exists, that variation will be found, on comparison of a
sufficient number of specimens, to be so gradational as to defy all attempts to use it as a
basis of specific differentiation. Of this we have a marked example in Operculina, six vertical
sections of which are shown in Fig. IX. Further, no dissimilarity between the form of the

Fig. IX.

e..

Vertical sectious of six specimeus of Operculina ; showing a remarkable diversity in tlie forms and proportions of the chambers

8

58

OF THE FORAMINIFERA GENERALLY :

septal plane in different individuals can be greater than that which often presents itself at
different periods of the life of one and the same individual. Thus, among tlie nauiiloid
Foraminifera, there is very commonly to be noticed a remarkable tendency to flattening- out
in the latest whorl ; the breadth of the spire being rapidly augmented, whilst its thickness
(or the space between its two lateral surfaces) is proportionally diminished. Of this, again,
we find a striking illustration in Operculina ; in which the attenuation of the last convolution

Fig. X

^.

Vertical section of the tluee outer convolutions of an Opcraihna, sliowing a complete change in the form and proportions

of the last convolution.

Fig. XI.

often proceeds to a far greater extent than in the example represented in the accompanying
fio-ure, the septal plane being thus converted in one turn of the spire from the form of a broad
arrow-head to that of a band so narrow as to be little else than a line, whilst it is
leno-thened in the same proportion. The form of the septal plane, moreover, is in direct
relation, not merely with the general contour of the shell, alike in its lateral and in its antero-
posterior aspects, but also with certain of its surface-markings. For if each chamber be
merely applied to the extremity of that from which it is budded forth, the whole of the
previously formed shell remains visible externally ; and thus, in the case of a nautiloid spiral,
all the whorls are traceable from its commencement to its termination. But it most commonly
happens that the earlier whorls are either partially or completely invested by the later:

where such investment is complete, nothing but the last whorl is
visible externally (Fig. XI) ; where, on the other hand, it is par-
tial, the earlier whorls maybe more or less clearly distinguished.
Now, the degi-ee of this investment is determined by the degree in
which the successive segments of the sarcode-body of the animal
send out lateral lobes that extend themselves over the previously
formed portion of the shell ; and this is manifested in the shell by
the development of what may be termed the alar prolongations
of the chambers, which are the portions formed to include
those lobes. Thus, in Fig. XII, we have an anterior view of
a nautiloid shell, in which the last whorl so little encroaches
on the preceding, that the septal plane s.p. terminates at the
an"-les h, h, which are but little nearer to the centre of the spire than the aperture a, which
lies against the margin of the preceding convolution. On the other hand, in Fig. XIII, we have
a like view of another nautiloid shell, in which the last whorl completely invests the preceding,

Lateral view of a nautiloid shell,
of which each convolution com-
pletely invests the preceding,
so that the chambers 1-S are
hidden bv 9-15.

PRINCIPLES OF CLASSIFICATION.

59

and the septal plane s.p. is here extended on either side into the " alar prolongations " a. p.,
a. p., until its angles h, h reach the umbilicus or centre of the spire. Now a difference of
this kind not unfrequently presents itself, •

not only between different individuals Fig. XII.

whose specific identity is demonstrated by
the gradational series that connects them,
but also between the different parts of one
and the same individual ; the latest whorl
often disengaging itself more or less com-
pletely, whilst each of the earlier whorls
was successively invested by that which
succeeded it. Hence it is obvious that no
such difference can be justly regarded as
a basis for specific distinction, until it shall
have been shown to be both constant in
its occurrence and uniform in its degree ;
the presumption being decidedly in favour
of its variability, until the contrary shall

have been established. It is in the genus Nummulites that the peculiarities in the
disposition of the alar prolowjations of the chambers, and of their intervening septa, seem
to have the greatest importance as differential characters, and have been most used for the
discrimination of species; but we shall find reason to question whether even there such
peculiarities have the uniformity and definiteness which are required to justify such an
employment of them.

72. Of surface-marUnfj there are two principal kinds, which are for the most part related
to the " porcellanous " and the " hyaline " types of shell-structure respectively. The surface
of the porcellanous shells, as already stated (t 57), is not unfrequently marked by striations
or by pittings, more or less conspicuous and regular in their arrangement ; and the value to
be attached to these must depend entirely upon the degree of constancy with which they present
themselves in each particular type. Thus in Vertehralina we shall find that the presence of
coarse striations, passing transversely between the septal bands (Plate V, figs. 17—25), is so far
constant in the first-formed portion of the shell (though very commonly wanting in the later
segments) as to afford important evidence in the determination of forms that might otherwise
be doubtful. So, again, the more delicate striation of PeneropUs (Plate VII, figs. 16, 18, 20)
is so constant and characteristic, that the exact similarity it presents in the " dendritine " and
" spiroline" forms (Plate VII, figs. 1,4, 12, 13, 21) becomes an important element in the deter-
mination of their merely varietal nature ; even its occasional obsolescence (figs. 2, 3) strengthen-
ing rather than weakening this conclusion, such obsolescence occurring after the same manner
in all these types. In MiUola, on the other hand, nothing can be less constant than the sculpture
which so remarkably distinguishes certain individuals (Plate VI, figs. 3, .5, 13, 14) as apparently
to justify their being ranked as well-characterised species ; for wherever a sufficient number of
individuals thus distinguished is brought together, there will be found some in which it is far
less conspicuous than usual, and others in which it is wholly wanting either on some part of

60 OF THE FORAMINIFERA GENERALLY :

the external surface or at some period of growth ; so that, a continuous gradation being thus
estabhshed between the most regularly sculptured and the perfectly smooth forms, it becomes
obvious that no valid specific distinction can be erected on such a basis in this type.

73. Among the "hyaline" shells, on the other hand, variety is given to the surface
marking chiefly by the interposition of bands or spots of non-tubular substance in the
midst of the tubular ; such portions being distinguished by their vitreous lustre from the
general surface, even when they do not project above it. Most commonly, however, they
are raised into ridges or tubercles ; and these are sometimes arranged with great regularity,
whilst in other instances they are extremely variable. Generally speaking, we find that when
either continuous bands or rows of spots of non-tubular substance repeat themselves with
anything like regularity in a direction trans vers/' to that of growth, these mark the position of
subjacent septa ; and, by the elevation of these septal bands, we have septal ridges or rows of
tubercles, such as are often strongly marked in the " cristellarian" type of Nodosaria (ex, PI. ii,
fig. 54), in Oppi-cuUna (Plate XVII, fig. 1), and in Cycloclypeiis (Plate XIX, fig. 2), But, between
these septal ridges, we often find a multitude of tubercular elevations ; sometimes arranged in
regular transverse rows, as in certain varieties of OpcrcuUna ; more commonly, however, with-
out any such symmetry, as in many Rotalia and TlanorbtdincB . These, instead of the vitreous
lustre, sometimes exhibit an opaque porcellanous whiteness (Plate XIII, fig. 15). In cases in
which the original walls of the shell are overlaid by subsecpient deposits, we very commonly find
that the size and prominence of these tubercles increase with every addition to its thickness ; so
that in section they present the appearance of cones whose base is at the surface of the shell,
whilst their apex points to its interior. This is often strikingly displayed in the umbilical
region of Opcrculhia (Plate XVII, fig. 1), and in the central regions of CydocJypeus (Plate XIX,
figs. 2, 5) and of Orbituides (Plate XX, fig. 2). The variability of any such ridges or tubercles,
however, is such as altogether to destroy their value as specific characters ; individuals in
which they present themselves under so pronounced and peculiar an aspect as to seem defi-
nitely differentiated by their presence from the ordinarj' type, being found to be connected
with it by a continuously gradational series ; whilst even on diff"erent parts of the very same
shell, the size, disposition, and aspect of the tubercles are found to vary so much as to render
exactness of definition altogether impossible.

m

74. Another kind of surface-marking in the "hyaline " series is given by ridges which
project from the shell, not transversely, but lonyHudinally, that is, in the direction of growth ;
these are very common in the genus Lagena (ex, PI. i, figs. 8-14), and in the protean forms of the
Nodosarian type (ex, PI. ii, figs. 36-48) ; but they are of no more value to the systematist than
those already noticed, since they vary greatly in the degree in which tliey are developed in
different individuals, and are frequently wanting on portions of shells which elsewhere present
them very strongly marked. The most remarkable modification of this kind of surface-marking
with which I am acquainted is the hexagonal areolation presented by certain " entosolenian ''
varieties of Layena (see ex, PI. i, figs. 29-32) ; ,this, however, is not more constant than the
similar areolation of certain varieties of Miliola, although it would at first seem to have more
value as a differential character on account of the difference of texture between the shell
substance of the ridges and that which forms the general surface. One other variety of

PRINCIPLES OF CLASSIFICATION. Gl

surface remains to be mentioned ; namel)% that hispid character which is given by the pro-
jection of conical spines from every part of it. Of this we have numerous examples among
the straight and slightly curved NodosaruB (Plate XII, fig. 2) ; whilst among spiral shells
we meet with it in the most pronounced degree in a varietal form frequently presented by the
young of Calcarina (Plate XIV, figs. 6, 7). The careful study which I have made of this last type
enables me to aflarra with confidence, that these conical spines are formed by an excessive
growth of the tubercles of non-tubular shell-substance already described, and that they usually
disappear with the advance of age, by an increase in the thickness of tlic ordinary shell
substance which fills up the spaces that intervene between them. And among the Nodusaria
they certainly have no more vahic as differential characters tlian the ridges already noticed.

75. Taking our stand, then, upon the characters by which the Order Reticularia is
difi"erentiated from otlier Rhizopods, — viz., the minute subdivision and the free inosculation
of the pseudopodia, the imperfect differentiation of the endosarc and the ectosarc, and the
absence both of nucleus and contractile vesicle, — ^we have finally to inquire how the group
thus constituted can be most naturally subdivided in accordance with the principles that have
now been laid down. At first sight, it would appear as if the groups of Gromida and
FoRAMiNiFERA Were so strong!)^ differentiated by the deficiency in the former of that
calcareous envelope which is the special characteristic of the latter, that they should constitute
two sections or sub-orders of corresponding rank ; and such a view has been adopted by
MM. Claparede and Lachmann (xxv, p. 34). If, however, we attach a greater value to
the characters furnislied by the animal than to those afforded by the material of its envelope
(and this appears to me the more natural method), we find that the affinity of the Gromida to
those Foraminifera whose shells, being imperforate, do not give passage to pseudopodia, is even
closer than is that of the Foraminifera having imperforate shells to those of which the shells
are perforated; whilst the systematic value of the difference in the material of the envelope
is lowered by the circumstance, that among the true Foraminifera we occasionally meet with
instances in which the only part of the shell that is really formed by an exudation from the
animal is the cement that holds together the particles of sand from which it derives its
solidity. Following out this principle, tlie whole Order Reticularia may be subdivided into
two primary groups, according as the envelope (whether membranous or shelly) is imperforate
or is perforated ; the pseudopodia in the former case issuing only from the single or multiple
aperture, whilst in the latter they proceed from the general surface of the body. The imper-
forate sub-order may be divided into three very natural groups, according as the nature of the
envelope is membranous, jjorcellanous, or arenaceous ; and thus we have the families Gromida,
MiLiOLiDA, and Lituolida. Throughout the perforated sub-order, on the other hand, the
texture of the shell is hyaline or vitreous, save in the few instances in which the ordinary shell-
substance is partially replaced by particles of sand ; and there seems no other l)asis for a
division of that sub-order into families, than that which is afforded by tiic mutual affinities
of its generic t3'pes.

The results of our inquiry up to this point, thei*efore, may be summed up as follows

.«

* Tlie nearest approach to the above principle of classification -wliich I fiud among preceding
systematists, is that hinted at, though not actually adopted, by j\I. Dujardiu (xxxvi). As the original

62 OF THE FORAMINIFERA GENERALLY.

Class RHIZOPODA, Order Reticularia.

Sub-order, imperforata.

Test membranous ..... Famil}' Gromida.

Shell porcellanous „ MUiolida.

Shell arenaceous ..... „ Lituolida.

outline of the system in which the Foraminifera first liad their true place assigned to them, the classi-
fication of M. Dujardin will always have an historical value, although its incompleteness has been
made apparent by subsequent researches. The Amihiens constitute the second, the Rhizopodes the
third, and the Actinophryens the fourth family of his Infusoria ; but as he distinctly states (p. 240) that
the structure of the animals is essentially the same in the first two cases, it is rather to be wondered
at that he should have limited the name Rhizopods to such as have the body enclosed in a testaceous
envelope. This envelope, he says, varies in consistence from a simple flexible membrane to a thick
calcareous shell, either solid or porous. But he does not regard these differences as equal in
importance to those presented by the form of the pseudopodial extensions of the sarcode-body,
according to which the group may be divided into two sections ; of which the first (corresponding to
Ehrenberg's family Arcellina) includes only the Arcella and Diffiugiw, whose pseudopodia are short,
thick, and rounded at their extremities, whilst the second comprehends all those whose pseudopodia
are filiform and much attenuated towards their extremities. This second section he subdivides into
three tribes ; the first composed of the genera Trinema, Euglypha, and Gromia (all discovered by him-
self), which are distinguished from Diffiugia only by the attenuation of their pseudopodia; the
second is composed of the single genus Miliola, which agrees with the ordinary Foraminifera in the
possession of a calcareous shell, whilst in having but a single large aperture from which the pseudopodia
extend themselves it corresponds with Gromia ; and the third includes the Foramimfera proper,
which he supposed to be all furnished with porous shells for the passage of pseudopodia from the
general surface of the body. It is remarkable how little change is required (and this rather in the
application of terms than in re-arrangement) to bring this outline into conformity with the more com-
plete system which subsequent research enables us now to frame. For if we extend the application
of M. Dujardin's term Rhizopodes not only to the Amibiens which precede them but to the Actino-
phryens which follow them in his classification, and transfer to the former from the central group the
genera Arcella and Difflugia whose animals are of the Amoeban type, and to the latter the genera
Trinema and Euglypha which are Actinophryan, we find the central group thus restricted to correspond
exactly with our Order IIeticulakia ; and the limitation or non-limitation of the pseudopodia to the
single or multiple aperture would probably have been adopted by i\I. Dujardin as the basis of his primary
divisions of that group, if he had been aware that Miliola, so far from being exceptional among Foraminifera
in this respect, is in reality the type of an extensive series. — Whilst this sheet is passing through the
press, I find that Prof Reuss has recently propounded to the Imperial Academy at Vienna (xci a)
a scheme of classification of which the principles are almost identical with my own. He considers the
composition and intimate structure of the shell to be characters of primary importance, and attaches but
little value in comparison to plan of growth. He still retains the distinction into Monoihalam.ia and
Polythalamia (which he terms Monomera and Polymera), but expresses himself doubtfully as to its
value.

CHAPTER IT.

OF THE FAMILY GROMIDA.

76. The members of the Family Gromida accord with the imperforate Foraminifera in
the characters furnished by their sarcode-bodj% M'hich puts forth its pseudopodial extensions
only from a single aperture ; but differ from them in having that body enclosed only in a mem-
branous test, which may be reduced to such tenuity as to be scarcely distinguishable. By
M. D'Orbigny this family was altogether ignored, no member of it having been known when
he first applied himself to the systematic study of the Foraminifera, and no mention havuig
been made in his subsequent writings even of its typical genus Groinia discovered by
M. Dujardin in 1835 (xxxv), notwithstanding the clear demonstration given by that
admirable observer of its close relationship to Miliola (xxxvi). Not less completely was
this type excluded by Professor Ehrenberg from his systematic arrangement of Bryozoa
(xl) ; the genus Gromia being apparently regarded by him as allied to Arcella and D'lJJlugia,
which he ranked as Infusoria. It was by Professor Schultzc (xcvii) that Gromia and its
allies were first introduced into a complete systematic arrangement of the Foraminifera ; but
he placed so much higher a value on the unilocularity of the " test " than on any other
character, as to associate them with Arcella and BiJjJugia, whose animals are of the Amoeban
type, with Trinema and Eughiplia, whose animals are Actinophryan in character, with Squamidina,
which has an imperforate calcareous shell of the Milioliue type, and with Orulina, whose shell
is perforated and hyaline, in the Family LagynidcB of his Monothalamia Testacea, — an
association which must be altogether incorrect if there be any truth in the principles laid down
in the preceding Chapter, as being those on which alone can any approach to a natural
classification of Foraminifera be founded. Between the " test" of Gromia and that of Arcella,
indeed, there is but little difference ; but between the animals which form and inhabit these
" tests" respectively, the difference is as wide as any that is known to exist in the whole
Rhizopod series ; and this difference has been cleai'ly recognized by MM. Claparede and
Lachmann (xxv).

Genus I. — Lieberkuhnia (Plate II).

77. This genus is the one of the whole Order Beticularia in which the envelope of the
sarcode-body is reduced to its minimum ; so that it approaches most nearly to the absolutely
naked condition, and may in consequence be most advantageously studied as a type of the
group, holding the same position in the Rcticulose series that Amccba does in the Lobose, and

64 FAMILY GROMIDA.

Adinoplirys in the Radiolarian. A detailed account of its very simple organization and of its
mode of life (so far as at present known) having been already given (^ 32), there is no occa-
sion here to repeat the description ; but it may be advantageous to point out that the origin
of the whole ramification of pseudopodial expansions from a single stem which is limited by
a definite envelope, shows Lieberkuhnia to be strictly conformable to the imperforate type.
From no other part of the body are pseudopodia given off, as would be the case if it had any
affinity to the perforated series.

Genus II.— Gromia (Plate III, fig. 2).

78. The genus Gromia was first constituted by M. Dujardin in 1835 (xxxv) for the
reception of a group of Khizopods characterised by the possession of a brownish-yellow, soft,
membranous, ovoidal or spheroidal " test," having a small round orifice, whence issue very
long pseudopodia, which ramify and become much attenuated towards their extremities. In
the membranous nature of its " test" Gromia resembles Arcella and Eii(jlyplia, but the character
of the animal entirely differentiates it ; and it thus holds in the Reticulose series a rank exactly
parallel to that oi Arcella in the Lobose, and oi Enr/li/jjlia in the Radiolarian. This genus has
since been especially studied by Schlumberger (xcix a); and still more recently by Professor
Schultze (xcvii), whose account of it is in some respects more complete than that of
Dujardin, but corresponds with his in all essential points.

79. The smooth, coloured "test" of Gromia, which commonly attains a diameter of
from 1-lOth to l-12th of an inch, looks to the naked eye very much like the egg of a Zoophyte
or the seed of some aquatic Plant ; and its real nature would not be suspected until, after an
interval of rest, the animal begins to creep about by means of its pseudopodia, and to mount
along the sides of the glass vessel that contains it. Some Gromia are marine, and are found
among tufts of Corallines, Ccramiacise, and other Alga3 ; whilst others inhabit fresh water,
and adhere to Ceratophylla, Confervae, and other plants of running streams. Various species
have been described, differing slightly in the size, form, and colour of the " test," and in the
proportional length of the pseudopodia ; but, with the evidence we have of the variability of
all such characters in other instances, these specific distinctions cannot be regarded as having
any valid claim to acceptance. The composition of the " test" has been studied by Schultze
(xcvii, p. 21), who states that it resists the action of boiling solutions of the caustic alkalies,
and that of the concentrated mineral acids, even sulphuric. With sugar and sulphuric
acid it gives a red colour ; whilst by iodine and sulphuric acid it is turned to a
blackish hue, with a tinge of violet. The organic substance which it seems most to
resemble in these reactions is cellulose, but it differs from cellulose in not being dissolved
by sulphuric acid ; and it would seem to have some relation to cJiitine and the
substance of the Iiorni/ tissues. Of the animal of Gromia, and of its mode of obtaining its
food, a sufficient account has already been given (^^ 33, 34) ; and it has only to be here
stated in addition, that the shell has no permanent attachment, but that the animal moves
slowly from place to place by the alternate extension and contraction of the pseudopodia which

GENUS LAGYNIS. 65

it projects in advance, those which it leaves behind it (so to speak) being retracted into the
general mass of the body, from which new ones are put forth in front.

Genus III.— Lagynis (Plate I, fig. 21).

79. It may be doubted whether this genus, first discovered by Prof. Schultze
(.xcvii, p. 56) in the Baltic sea in the year 1849, should be ranked as an aberrant type of
the family Gromida, or should be removed to the Adinoplirijan group ; the intermediate
character of its pseudopodian extensions, and the strong resemblance of its " test " to that of
JSurjlyjjha, being such as to justify either position. This " test," which seldom exceeds 1 -240th
of an inch in length, is unattached, membranous, transparent, and elastic, and has somewhat
the form of a retort with a prolonged neck and a large aperture. The sarcode-body rarely
fills its cavity, the posterior part of which is generally unoccupied save by four tapering pro-
longations, that come off from the hinder part of the sarcode-mass which occupies the central
part of the cavity, and extend themselves backwards so as nearly to meet each other at the
posterior extremity of the "test" (Plate I, fig. 21, .\). These processes, with the part of
the sarcode-body from which they proceed, are composed of a granular sarcode more
opaque than the rest; and this is disposed, in the middle portion of the cavity of the test,
around a bright globular centre. The anterior portion of the cavity, on the other hand, is
occupied by sarcode of peculiarly pellucid character ; and it is this which extends itself into
the pscudopodia that issue from the orifice. These pseudopodia, like those of the HHiculuria
generally, are very slender, in this respect contrasting very strongly with those of the typical
Ammham (though not unlike those of A. porrecta, fig. 18), but more resembling those of
certain Actinopliryans. They diverge and occasionally subdivide ; but do not extend to more
than two or three times the length of the shell; and they show little or no tendency to
reunite (as in Gromia), so as either to form a network or to establish fresh centres of ramifi-
cation. The sarcode-substance has not been seen to extend itself (as in Gromia) backwards
from the orifice over the surface of the test, so as to give off pseudopodia laterally and
posteriorly. Occasionally the sarcode-body is found to occupy only the posterior part of the
cavity of the test, and to present the form of a sphere without any prolongations, its bright
pellucid centre being still distinguishable in the midst of the darker substance (fig. 21, b).
Whether this retracted condition has any relation to the " encysted " state of Infusoria, is a
point still to be determined. It is pointed out by Prof. Sehultze that the " test " of
Lru/yiits hears a close resemblance to one described by Perty (lxxxii, Plate viii, fig. 21),
under the name of Eiyhipha currala, as having been found empty on the Simplon, at a height
of from 4000 to 5000 feet.

CHAPTER V.

OF THE FAMILY MILIOLIDA.

80. The series of generic types which is marked out by the porcellanous texture of the
shell {% 57), and by those other structural characters which are associated with that dis-
tinctive feature {%% 62 — 65), includes so great a variety both of modes of conformation and
of grades of development, that at first sight the association of all these into a single family
would seem altogether unnatural. As we proceed in our study of them, however, we shall
find that from the lowest to the highest of these forms each is most remarkably connected
with other parts of the series by links of affinity so strong as to forbid their dissociation ; so
that, starting from the humblest or simplest types, we are gradually conducted, with scarcely
any decided interruption, to the highest or most specialised. Thus in SquamuUna (Plate I, fig.
22) we have a raonothalamous shell, of which the shape, although not very definite, seems to
preclude any extension or super-addition. In Cornuspira (Plate V, fig. 1 6) we find that the shell,
although still remaining monothalamous or undivided, is indefinite in its mode of increase,
receiving a succession of increments which foreshadows the successional addition of new
chambers in the Polythalamia. From this undivided spiral to the regular, scarcely divided
spiral of certain " spiroloculine " forms of Mlliola, the transition is almost insensible ; from the
" spiroloculine" we pass by eas)' steps to all the other forms of the Milioline type; and certain of
the most aberrant of these establish the transition to Hauerina and Fahidaria, in which last the
Milioline type seems to reach its most complex phase, the cavity of the shell being minutely
subdivided, as in Orbiculina and Alveolina, and the single large orifice into being replaced
by multiple pores. Returning to our starting point, we shall find in the proteiform Nubecu-
Jaria (which seems as much related to SquamuUna as to Cornusjnra) a sort of primitive sketching-
out of the various plans of growth which are more perfectly evolved in higher parts of the
series ; all its forms, however, being obviously but varieties of one type, of which the most
definite positive character is afforded by the incompleteness of the separation between the
successive chambers. The substitution of the rectilineal for the spiralis more definitely mani-
fested (though still under a great variety of aspects) in Vertcbralina, and the division of the
chambers is more complete. From this we pass almost insensibly to Penerojjlis, which also
presents itself under the form of a spiral giving place to a straight line, and in which the
elongated fissure that constitutes the aperture in Vertcbralina is broken up into a row of
separate pores. The subdivision of the chambers of Peneroplis by secondary partitions con-

GENUS SQUAMULINA. 67

verts it into an OrbiciiUna ; and this, in the later stage of its existence, usually takes on the
cyclical mode of growth, whereby it is linked on to OrbitoKtes which ordinarily follows that
plan from the commencement ; whilst, on the other hand, the mere lengthening of its axis of
growth carries us from the discoidal Orhiculina to the fusiform Aheolina. The most peculiar
types at present kn6wn to belong to this series are Badylopora and Acicularia, which seem
to be formed upon somewhat the same plan as OrbitolUes, though separated from it by a
wider interval than exists elsewhere. — Hence we seem fully justified in bringing together
all these forms into a single Family, and in giving to this family a designation derived
from that one of its genera which seems most wideJij diffused both in space and in time, there
being none which can be regarded as typical in regard to form. The following tabular
arrangement of this family may assist in the appreciation of the relationships of its members.

FAMILY MILIOLIDA.

Squamulina.

I I

Nubecularia — Cornuspira.

I I

Vertebralina . . Miliola.

I I

Peneroplis . . . Hauerina.

I I

Orbiculina . . . .Fabularia.

I I

Alveolina Orbitolites.

I
Dactylopora.

I
Acicularia.

Genus 1. — Squamulina (Plate I, fig. 22).

81. The genus Squmitdina was instituted by Prof. Schultze (xcvii, p. 56) for a minute
monothalamion of which he found several specimens at Ancona, adhering to the surface
of Algae and to the side of a glass vessel in which sea-water had been long kept. The shell,
whose largest diameter is about l-.300lh of an inch, has the form of an irregular plano-convex
lens, being usually flat, or nearly so, on its attached side (which accommodates itself to the
surface whereon it grows), and convex on its free side, on some part of which — usually about
half way between the centre and the periphery — is a wide orifice from which the pseudopodia
issue. The shell is calcareous and opaque, and is destitute of pores ; its adherent layer is very
thin, and is with difiiculty detached from the surface to which it is attached. The substance
of the animal is of a brownish-yellow colour, as in Gromia ; its pseudopodia, however, seem
fewer and less disposed to subdivide and inosculate.

68 .FAMILY MILIOLIDA.

Genus II. — Cornuspira (Plate V, fig. 16).

82. Hisfori/. — The genus Cornuspira was instituted by Prof. Schultze (xcvn, p. 40), for
those calcareous-shelled Foraminifera which form a flat spire like that of a Planorbis, and
have their cavity simple and undivided ; and two species were distinguished by him, one
of them, C. planorbis, having the shell solid, the other, C. perforata, having it finely
porous. Prof. Williamson (ex, p. 91), whilst recognising both these forms, and describing
another in which the shell is arenaceous, reverted to the generic name Spiri/Ii/ia, which
had been previously given by Ehrenberg to a shell resembling Schultze's C. perforata,
and included all three forms under that designation ; at the same time changing the
specific name of Schultze's C. planorbis to adopt that of foliacea, which had been pre-
viously bestowed by Philippi upon a more advanced form of the same organism. Soldani
(by whom this shell seems to have been first figured), Philippi, Williamson, and Messrs. Parker
and Rupert Jones, have all recognised in its opaque-white porcellanous character a close
resemblance to that of the MilioUnce. This resemblance is unquestionable ; and if there be any
truth in the principles enunciated in the two preceding chapters, it is obvious that the imper-
forate porcellanous spirals and the perforated hyaline spirals must be regarded, in spite of
their almost exact resemblance in external form, as belonging to two fundamentally different
types. Reserving, therefore, the name Spirillina as the generic designation of the latter, I
concur with Messrs. Parker and Rupert Jones in thinking it expedient to make use of the
name Cornuspira as the distinctive appellation of the former.

83. External Characters. — The shell of Cornuspira is a simple flat spire, the suc-
cessive turns of which at first increase but slowly in width, but which at last opens
out rather suddenly, like that of many other Foraminifera growing upon the same type
(Plate V, fig. 16). The successive convolutions are in contact at their edges, but the later
do not extend themselves over the earlier, so that the whole of the spire remains visible
externally on each lateral surface. Not the least appearance of septal bands or constric-
tions presents itself at any part of the spire ; except that a slight depression may some-
times be detected, which marks ofl^ the primordial chamber from the spire that proceeds from
it. In the young form of this shell the tube is cylindrical or nearly so, and its aperture is
round ; but as it advances in age and flattens itself out, whilst the spire undergoes a rapid
increase in width, its two surfaces become so closely approximated that the form of the
aperture changes from a circle to a long, straight-sided fissure (fig. 1 6, a). The compressed
whorls of the adult often show a series of irregularly alternating ridges and depressions,
which cross the course of the convolutions with a convexity directed forwards, and these
seem to mark the successive additions which the shell has received. Occasionally, as in many
higher types, an abrupt narrowing of the spire takes place, so that the convolution is con-
tinued on the smaller scale of some previous portion of the whorl, as is shown in fig. 16.

84. Internal Structure. — The entire absence of septal divisions, indicated by the external
aspect of this type, is proved by an examination of its internal structure, which shows that
the cavity occupied by the sarcode-body of the animal is perfectly uninterrupted, except

GENERA CORNUSPIRA. AND NUBECULARIA. 6.9

where (as already mentioned) a slight constriction marks ofif the primordial chamber at the
commencement of the spire. Hence the body will present no appearance of segmentation
except at that point, and the large size of the external aperture will enable it to extend
its pseudopodia most freely into the surrounding medium. — The Cornuspira foliacea, which
is at present the only known form of this type, attains the diameter of l-8th of an inch.

85. Affinitlea. — In CornusjnrH we have a sort of rough sketch of the higher type of
helicine Foraminifera, which it greatly resembles in external form, but from which it differs
in the simplification of its structure resulting from the absence of segmentation in its sarcode-
body. Its growth, like theirs, is unlimited; and thus, although actuallj/ monothalamous,
it may be considered ixs /loteiilialli/ polythalamous (^ G2).

86. Geot^raphical and Gcolot/ical Distribution. — This type is at present very generally
diffused through various seas, its shells growing attached by one of their lateral surfaces
to Alga; and Zoophytes, usually at no great depth. It has not been met with in any
formation of older date than the Eocene; but it abounds in the "calcaire grossier," and
presents itself at every subsequent epoch.

Genus III. — NuBECUL.\RiA (Plate V, figs. 1 — 15).

87. Hislof!/. — The genus Niiheadana was first established by Defrance (xxix) for the
reception of an assemblage of small calcareous bodies of variable form and extremely indefi-
nite characters, which he found within univalve shells of the " calcaire grossier." He expressed
himself as altogether undecided in regard to the place to be assigned to them in the animal
series; but in figuring them he grouped them with Zoophytes (xxix, Zooph., PI. xliv, fig. 3).
A comparison of the figures given by him (imperfect as these are) with the figures previously
given by Soldani (ci) of certain of the bodies to which he gave the general designation Serpula,
serves to show that this type had been previously recognised by that painstaking observer.
The indefiniteness of Defrance's characterisation of the genus seems to have prevented its
adoption by subsequent authors ; thus we find that even Blainville did not accept it (vi a),
though retaining Defrance's figures and the name appended to them on the plate ; and
Lamarck makes no mention of it. The genus was entirely ignored by M. D'Orbigny, though
one of its multiform varieties was described and figured by him under the name Webhina riigosa
(v, PI. i, figs. 16 — ^18, and Lxxiii, p. 74, PI. xxi, figs. II, 12). It has, however, been noticed by
M. Dujardin (xxxviii), who remarks of it that its proper place is probably rather among Fora-
minifera than among Polypifera. The firm establishment and true characterisation of the genus,
however, can only be fairly attributed to Messrs. Parker and Rupert Jones, by whom it has
been especially studied in its recent as well as in its fossil forms (lv, p. 455), and who have
kindly furnished me with the materials on which the following account of it is based.

88. External Characters. — No Foraminiferous shells are more protean in shape than
those of Nubecularia, for we find them presenting almost every plan of growth that is to be
found among Foraminifera. It is one of their distinctive characters that they attach themselves
to other bodies, the surfaces of which they use as part of the walls of their own cavities ; and

70 FAMILY MILIOLIDA.

thus it happens that they mould themselves to the shape of the bodies to which they are adherent,
and that the plan of their own conformation varies accordingly. It is when growing on flat sur-
faces, such as those afforded by shells or sea-weeds, that Nubecularia best exhibit their characters
(Plate V, figs. 6, 13) ; when, on the other hand, they extend themselves over the projections of
fohated shells, or ensheath the stems and branches of Zoophytes, Corallines, &c., they often lose
all external traces of definiteness of plan (figs. 8, 9), and even their internal structure would
be unintelligible if the simpler forms did not supply the means of interpreting it. It is difiicult
to say what ought to be accounted the typical plan of conformation in this genus ; but as it
usually (though not always) commences in a sjjiral, which subsequently gives place to other
modes of growth, this may be conveniently adopted as the starting-point. The spiral shell
of Nubecularia differs from that of Cornuspira in several very important particulars. In the
first place, it is frequently deficient altogether on the attached side (figs. 1 — 3), so that the
cavity of the tube is there bounded only by the surface to which its edges are adherent, and
the form of its section is not circular, but semicircular. Sometimes, however, a layer of shell
is deposited on that surface, so as to close-in the tube (figs. 4, 1 1, 14) ; but this layer is so thin
as to require the support afforded to it by the surface to which it is adherent. On the other
hand, the -shelly substance of which the unattached side of the tube is composed is deposited
in unusual abundance, so as not only to form a very thick wall on the exposed surface, but to
fill up the grooves which would otherwise be left between the successive coils of the spire.
Thus it often comes to pass that the distinction between the coils is altogether obliterated,
and only from the general outline of the entire shell could it be supposed that a spire is
concealed beneath. This deficiency of shell on the attached side, with such an exuberant
thickness on its exposed side as masks its characteristic form, is observable not merely in the
spiral NubecularicB, but also in those curved, straight, zigzag, ramifying, and acervuline
varieties through which this generic type will be shown to range (fig. 9).

89. Internal Structure. — In those forms oi Nubecularia which spread themselves over plane
surfaces, the internal structure is readily disclosed by detaching the shell from its adhesion, and
looking at it from the under or attached side ; for its cavity is then either laid open altogether
(fig. 1), or becomes visible through the thin pellicle of shell which covers it (fig. 4). In the
most regular spiral forms the spire commences in a spheroidal chamber, from which it is
separated by a slight constriction, and it then rapidly opens itself out, especially in the second
or third whorl. Its cavity is partially divided at irregular intervals by imperfect septa, formed
by inflections of the walls of the tube, which curve inwards with a convexity directed forwards,
but stop far short of meeting at the axis of the tube, so that a wide aperture of communication
is left between the adjacent chambers. When the spire enlarges, a dilatation is seen beyond
every one of these constrictions, the narrowed aperture of one chamber being received, as it
were, into the dilated base of that which succeeds it (fig. 5). This is for the most part better
seen, however, in the ^//-ff^^/// growth (fig. 10), to which the spiral convolution very commonly
gives place after having made two or three turns ; the axis of growth alone being changed, and
the structure of the tube and its partitions remaining the same. This straight mode of growth
may prevail from the commencement, individuals sometimes presenting themselves in which
the spire is altogether wanting. Sometimes the new chamber is formed at the side instead
of in the axial hue of the preceding, so that the direction of growth is suddenly altered.

GENUS NUBECULARIA. 71

Sometimes, af^ain, a new chamber is formed at the side as well as at the end of the preceding, and
thus a branch may pass off at a considerable angle from tlie main axis (fig. 12). More commonly,
however, wlien such a lateral gemmation takes place, the new series of chambers which thus
originates advances along the side of the preceding (fig. 7) ; and by further offsets of the same
kind these parallel series may multiply to any extent, the new chambers sometimes arching
over those from which they are derived, so as even in these flat spreading forms to mark the
tendency to an acervuline aggregation. Furtlici-, the axis of growth may be neither straight
nor spiral, but may bend or twist in any direction ; the chambers still succeeding one another,
either in a single linear series, or in ramifying extensions, or in multiple rows ; and nothing
then marks the generic type save the texture of the shell, its attachment by one of its surfaces,
and the narrowing of the chambers behind the constrictions, followed by a dilatation in front
of them.

90. Instead, however, of extending itself in length, the shell not unfrequently widens
itself out so much, that the distance across the chambers is far greater than that which inter-
venes between the successive septa ; and it is then to be observed that, between each chamber
and the next, there are two or more apertures in the septum that divides them (fig. 15). This
plan of growth is carried to an extraordinary extent in the specimen represented in fig. 13, in
which the enormous increase in the transverse dimensions of the chambers is accompanied by a
great multiplication of these septal communications (fig. 14), so that a NiibeciiJaria formed upon
this type becomes a sort of rude sketch oi Penerojdis. In not a few cases, again, the growth takes
place almost from the commencement on the cyclical ^\n.xi (fig. 11), the first-formed chambers
extending themselves around that which is occupied by the primordial segment, and budding
off new chambers in all directions ; the successive chambers communicate with each other
laterally, as well as in a radial direction ; and thus a sort of sketch is presented of the plan of
growth characteristic of Orhitolites and Plunorbulina, to the lower forms of which last, indeed,
this type of Nuheeularia (the chambers of which I have always found to be much smaller than
the average) often presents a decided analogy.

91. Either of the foregoing modes of growth may give place to one in which no
regularity whatever can be traced, the successive chambers being no longer added on the
original plane alone, but piling themselves upon one another, without any discoverable system,
so as to imitate the acervuline growth which Planorbulina sometimes takes on. This is espe-
cially liable to happen with NuhccuJaricc that cluster around the stems and branches of
Corallines, Zoophytes, &c. ; and thus it comes to pass that, as already remarked, not only
does their external configuration become altogether amorphous, but their internal structure
seems to be entirely destitute of arrangement. By a careful comparison of the intermediate
forms, however, the true nature of these amorphous acervuline growths, as derivations from
the simpler and more regular types, is unmistakeably demonstrated. In the larger and
coarser acervuline specimens, it is not unfrequently to be observed that the surface is
roughened by the inclusion of fine particles of sand (which seem to be composed of commi-
nuted shell) in the proper calcareous substance of their shells ; but this substance is never
replaced by sand,, as in the truly arenaceous types.

72 FAMILY MILIOLIDA.

93. Affinities. — The type which has now been described is of no common interest, as
displaying the first nisvs of a Rhizopod towards the production of a multilocular shell, and as
marking out, though in a rude and indefinite form, the principal plans which are evolved with
much greater completeness and regularity in the higher types. Niibccularia is obviously
allied to Cornuspira on the one hand, and to Vertebralina on the other ; it cannot, however, be
said to be truly intermediate between those genera (though some of its forms approximate to
each), because it difi"ers from both of them in the deficiency of the shelly wall on one side, as
well as in the rude and almost amorphous aspect of its free surface.

93. Geographical Distribution. — The shells of this genus are, for the most part, inhabitants
of the warmer seas, being especially large and abundant in the Laminarian zone, in which
they sometimes attain the size of hemp-seeds, or even of split peas ; whilst, when brought up
from deeper water, attached to the shells of large Mollusks, they are much more minute.
They also occur in a detached condition, associated with other Foraminifera, in many recent
sea-sands from shallowish water.

94. Geoloyical Distribution. — Nuhecularia are abundant in some of the French Tertiaries,
have been met with attached to GrypliacB, &c., in many Oolitic Clays, and have been recog-
nised in abundance (though the examples were very minute) in the Triassic Clay of
Chellaston.

Genm IV. — Vertebralin.\ (Plate V, figs. 17 — 25).

95. Histori). — The genus Verlebralina was first characterised by D'Orbigny (lxix) in
1826 ; the name which he has assigned to it having been apparently suggested by the resem-
blance presented by some of its forms (Plate V, fig. 22) to the vertebral column of a Shark.
On account of its spiral commencement he placed it among his nautiloid Helicnslegues, though
admitting that its position there is anomalous (lxiii, p. 120). Its relationship to the
Milioline type was first clearly indicated by Professor Williamson (ex, p. 89), who has given
an excellent description of its characteristic form, and has very properly reunited with
Vertebralina striata, the V. cassis and V. mucronala, of D'Orbigny, the diiferential characters of
which are too slight and inconstant for their separation. He was not aware, however, of
the extraordinary poh/jnorphism which this type is found to display when the comparison is
extended through a sufficiently wide geographical and geological range.

96. External Characters. — The aspect of the shell in Veriehralinais generally opalescentand
brightly polished, and its surface is usually marked by delicate, longitudinal striations, which
have the strength of ribs in the thick-walled and more strongly characterised specimens, such
as D'Orbigny's V. mucronata (xcii, PI. vii, figs. 16 — 19), but which become obsolete, or even
disappear entirely, on the later portions of the more delicate and more aberrant specimens.
More rarely the surface is pitted. The shell is complete on both sides, and is usually a
symmetrically flattened tube ; it has no other attachment to the surface on which it grows, than

GEIMLS VERTIiBRALINA. 7:5

tliat afforded Ijy the sarcodc-ljody of the animal itself, ov by the gelatinous investment
of tlie sea-weed to which it adheres. Its growth nearly always eommences either in a regular
spiral or in a Milioline modification of it, each turn of the spire being commonly formed
(as in Hdiii'rina, *] 112) by three chambers, or more rarely (as in the ordinary MUiolee,
^ 1 04) by two ; and it was on certain forms which are at first strongly milioloid and
afterwards uniserial, that D'Orbigny founded his genus Arliculinn. The earlier whorls
of the spire are generally inclosed by those which succeed them ; but sometimes they are
merely surrounded by them, so that the whole of the spire remains apparent. The septa
are marked externally by depressed bands, which are not crossed by striations. After
making from two to four turns, tlic shell continues to grow in a straight line ; the succes-
sive chambers (usually to the uuml)er of five or six) being sometimes of extremely uniform
size, subcylindrical in shape, and disposed with great regidarity (fig. 22) ; whilst in other
cases they are progressively compressed, so that the shell becomes flatter and wider
(fig. 25) ; and they are sometimes disposed in a zigzag manner. In either of these cases, how-
ever, the type is very easily recognised by the form of the aperture, which is a simple fissure
with lips slightly everted, extending along the whole breadth of the septal plane ; and it is
further to be noticed that behind each septal plane there is a more or less well-marked con-
striction, after which the walls of the chambers open out again. These constrictions are some-
times marked in an unusual degree by the very sudden enlargement of the new chamber
formed beyond, as in the specimen represented in fig. 23. Sometimes, on the other hand,
the tendency to increase appears suddenly checked, the new chamber being considerably
smaller than that which preceded it (fig. 21), the dimensions of which are only again
attained after a progressive increase continued through several chambers. A similar teraporar)-
dwarfing has been already noticed in Cornnspira, and seems liable to occur in any type of
polythalamous Foraminifera.

97. Inlernal Sfrucftcre. — On laying open the shell of Vcrtchralhia, its cavity is found to
correspond very closely with its extei-nal contour, the walls of its chambers being everywhere
of very uniform thinness. The septal divisions are disposed at much more regular intervals
than in Nuhccularia, but still have rather the character of constrictions formed by an inflection
of the walls, than of regular partitions ; and the wide aperture in each septal plane can scarcely
be difl'erentiated from that of Nuhecularia, except in the somewhat patulous character which
it derives from the slight eversion of its lips.

98. Varieties. — The typical form just described is liable to a great modification in cither
of two principal directions. On the one hand the chambers may become nearly cylindrical
in form, and at the same time narrowed and elongated, so that the straight portion of the shell
is drawn out into the form of a rod (fig. 19), though still presenting its characteristic con-
traction and subsequent opening-out at each septum ; whilst the aperture from a narrow-
fissure becomes circular, or nearly so. This rectilineal elongation of the chambers may
extend even to the first-formed portion of the shell, the primordial chamber and its imme-
diate successors being uncoiled (as it were) into a series of long cylinders laid end to end in a
straight line, the striated and pitted surface of which, together with the occurrence of
intermediate modifications of form, mark their derivation from the ordinary type. On the other

10

74 FAMILY MILIOLIDA.

hand, the progressive -widening-out of the chambers may go on to such an extent as still
more to disguise the fundamental type, especially when they not only become extremeh'
elono-ated transversely, but even wind themselves round the edges of those previously formed,
so as almost to meet on the opposite side of the original spire (fig. 18). Even such an
extremely aberrant form of the one here represented, which was distinguished by Lamarck
(lix and lx) under the names Benulina and Benidites* (expressive of the resemblance of
its shape to that of a kidney), is distinctly recognisable as a modified Vertehralina by the
exact conformity of the first-formed portion of the shell to the regular type, and by the
characteristic form of its aperture, which is a fissure extending along the entire margin of
the last nearly circular chamber ; and, as already pointed out (^ 89), a similar tendency is
common in other typical forms of this division of Foraminifera. Arrests of development at
the spiral condition, sometimes producing a strong resemblance to Miliola, are not uncommon
in either of the varietal forms of Vertehralina (figs. 17,20); and it is thus that the broad
specimens distinguished by D'Orbigny (xcii, pi. vii, figs. 14, 15) by the name V. Cassis,
have been produced. A curious dwarfed example, from a depth of 360 fathoms in the
Mediterranean, is represented in fig. 24.

99. Affinitief;. — It is obvious that Vertehralina may be considered as an advance upon Nuhe-
cularia, alike in the symmetrical conformation of its shell, and in the more definite plan of its
o-rowth. In that early condition in which it is sometimes arrested, it presents a close afiinity
to the MilioUne type ; whilst its compressed and especially its reniform varieties bring it into
close relationship to Peneroplis, which it often strongly resembles in shape, being always distin-
guishable from it, however, by the nature of the septal aperture, and generally also by the
inferior lustre and opalescence of the shell.

100. Geograpldcal Bistrihution. — Although specimens of Vertehralina are occasionally met
with among the Shetland islands, yet there is strong reason to believe that they have been trans-
ported thither from some warmer region ; as this genus seems, like Peneroplis, to belong
properly to tropical and sub-tropical seas, through which it is pretty generally diffused,
although in far less abundance than Peneroplis. '

101. Geological Bistrihution. — This genus presents itself in various Tertiary deposits ;
and it is from these that its most aberrant forms are supplied, although approximations to
them are furnished by their existing representatives.

Genus V.— Miliola (Plate VI, figs. 1—33).

103. History. — The generic term Miliolites was applied by Lamarck (lviii) in 1804 to
certain fossil forms belonging to a very common type, of which examples had been noticed
by LinnEeus (lxiii) as Serpula seminulum, by Soldani (ci) as Frumentaria, and by Montagu
(lxv) as Vermiculum; the designation having been apparently suggested by the resemblance

* These names are erroneously cited by Prof. Williamson (cs, p. 44) as synonyms of Peneroplis.

GENUS MILIOLA. 75

to millet-seed borne by the minute bodies to which it is applied. The Lamarckian genus was
adopted by various subsequent writers ; its name being modified to 3Iilio/rt or Miliolina for
the purpose of including the recent forms, which diifer in no essential particular from the
fossil. But in M. D'Orbigny's first systematic ari'angement of the Foraminifera (lxix) he
broke up this genus into the genera Uniloculina, Biloculina, Triloculina, Quinquelocidina, Sjpiro-
loculina, Adelosina, and CriicilocuUna ; and these he associated with Sjiharoidina (of which the
examples he cites as typical are really allied to Glohii/erinn, having a perforated hyaline
shell), and Articidina (which is in reality a varietal form of Vertcbiyi/lna, ^ 90), into his Order
AgathistivGUES ; his definition of which might have served as the generic character of
Miliula, if it had been founded on a correct conception of its typical structure. To the fore-
going genera, D'Orbigny subsequently added Fabularia (at first wrongly placed by him else-
where), a type which will hereafter be shown to present a peculiar development of the Milio-
line (1 116). Our reasons for reuniting the first seven of the genera just enumerated, with
all their multitudinous species, under the single type Miliola, without attempting to establish
even specific differentiations, will presently become apparent. With regard to his generic
divisions it is not a little singular that M. D'Orbigny should have remarked as follows : —
" We tliink it diflicult to find genera more distinct one from another than are those of this
Order. They present forms so sharply defined, that there really exists no transition between
them; and thus any one by a few liours' study will always find himself able to distinguish
them " (lxxiii, p. 256). Now although a few hours' study, prosecuted after the fashion of
M. D'Orbigny, may lead to an acceptance of his generic and specific distinctions as valid, yet
in precise proportion as that study is prolonged, and is made to include a sufiiciently large
number of examples of this type, brought from all the seas and from all the geological deposits
in which it occurs, do its results pi'ove to be of quite an opposite character. For the types
which were represented by M. D'Orbigny as so sharply defined, are found, on careful compa-
rison— as has been shown by Mr. W. K. Parker (lxxv) on whose view of tliis genus my own
account of it is based — to graduate into one another so insensibly, that no line of demarcation,
either specific or generic, can be drawn between them; so that no middle course can be
adopted between ranking them all as varieties of one species, distinguished by the degree
and direction of their divergence from a central type, and multiplying almost indefinitely
the number of species by adopting the most trivial modifications of form or surface-marking
as differential characters. This truth has already been partly apprehended by Profs.
Schultze and Williamson ; the former of whom (xcvii) has reunited the genera Trilocidina
and (luinqudocuHna under the generic designation Miliola ; whilst the latter (ex) has brought
them together under the name Miliolina, with the addition of Adelosina, which he rightly
states (p. 89) to be nothing else than a young form of the same type, distinguished by the
peculiar retort-shape of the primordial and the next succeeding chambers. Prof. Williamson
truly remarks (p. 80) that "none of the Foraminifera are more liable to variation than those
comprehended in the Lamarckian genus Miliolitcs ;" and adds (p. 87), that some of his "most
able correspondents, who previously thought that the species of Miliolinm ought to be made
much more numerous, on endeavouring to group the specimens in their cabinets according
to such views, found their difliculties increase with the multiplication of their specimens."

103. External Characters and Internal Structure. — The essential plan of conformation in the

76 FAMILY MILIOLIDA.

whole Miliolinc series is so simple, that it may be readily apprehended from a survey of the
external features of its fundamental type. Yet these features are liable to be so completely
masked, as altogether to lose their chai-acteristic aspect ; and since there hence arises so com-
plete a want of agreement between external characters and internal structure, as leads to the
entire misapprehension of the latter if too exclusive confidence be placed in the former,
it seems desirable to study both together in such a manner as to bring out their true relations.
And in this way we shall come to perceive the fundamental unity which prevails through a
range of varietal modifications so wide, as at first sight to appear to justify the creation of
an almost unlimited number of genera and species.

104. The fundamental " idea" of a MiJiola is best displayed in such a form as that
represented in Plate YI, fig. 1, which shows but little departure from the continuous spiral of
Cornusjjir'i ; the diifcrence consisting chiefly in this, — that each turn of the spiral is interrupted
at two opposite points by a constriction followed by an enlargement : and that, as the inter-
ruptions in successive turns are always at the extremities of the same diameter, the whole
spire is made up of a series of half-turns arranged symmetrically on its two sides. Each of
these half-turns is larger than that Avhich preceded it, but its dimensions scarcely change
between its two ends; so that the increase in the diameter of the tube is not gradual, but
takes place at successive intervals, each chamber being not only longer than its predecessor
on the opposite side, but also larger in sectional area. The form of that area departs from
the circular, in consequence of the tendency which each turn of the spire has to extend itself
in some degree over the preceding. Although this extension is but slight in the example we

. are considering, it is enough to give a concave instead of a convex border to the inner
wall of the chamber; which inner wall is, in fact, nothing else than the outer wall of the pre-
ceding turn, the shelly tube of the new chamber being there incomplete (^ 62). The
aperture of the last chamber is somewhat constricted : and it is further encroached-on bv
a tongue or tooth-like projection of shell substance from its inner margin (figs. 16 — 18) ; this
pi'ojection, which may be conveniently termed the " valve," varies greatly in size and form,
but when most developed, it converts what would otherwise have been a free nearly circular
passage into a comparative!}' narrow cresccntic slit. A similar " valve," whicli may be regarded
as a rudimentar}' septum (^ 109), exists at each of the constrictions that marks the division
of the chambers.

105. It is comparatively rare, however, to find so slight a departure from the regular
spiral plan, as is shown in specimens of the kind just described. For in by far the larger
number of cases, the diameter at the two extremities of which the septal constrictions occur
is more or less elongated ; and this elongation may proceed so far as to give it twice the
length of the transverse diameter (fig. 2), thus substituting for the spirality of the original
type an apparently Uhiicral arrangement, which has caused D'Orbigny and his followers to
define the Miliolinc group as if the shell were composed of " chambers clustered ='■ on two,
three, four, or five faces of a common axis.

* For the word pelototmees, \Tliich is intended to indicate the kind of aggregation produced by
■winding a ball of cotton, there is no proper equivalent iu our language.

GENUS MILIOLA.

77

Diagvaiiiiuulic ie(jrcscii-
tation of tlie Animal of

Hence it is ob-

106. The conformation of the sarcode-body of the animal obtained by the decalcification
of the shell, exactly corresponds with what the characters presented by its envelope would
lead us to anticipate. Starting from the ordinary primordial segment

(Fig. XIV, o), we find this giving origin, by a constricted neck or lu;. XR.

"stolon," to the first longitudinal segment 1, which doubles round one
side of it, and is then again constricted into a " stolon ;" from this pro-
ceeds the second longitudinal segment l', whicli passes round the other
side of the primordial spheroid, and, liaving extended itself beyond the
first, narrows itself at the opposite end of the diameter into a stolon ; from
this proceeds a third longitudinal segment 3, whicli passes round the
first and extends beyond it, giving origin, by a constricted stolon, to a
fourth 1, which in like manner passes round the second and extends
beyond it ; and this mode of increase may continue until a considerable
number of segments have lieen formed on either side of the primordial
spheroid, the last extending itself into pseudopodia at its termination,
vious that each segment grows in a direction contrary to that of the segment which
immediately preceded it, but corresponding to that of the ante-penultimate ^segment;
and that the pseudopodial extensions will be put forth alternately from one and the other
extremity of the body. And it is further obvious that this Milioline type involves, so
far as the structure of the animal is concerned, no more considerable departure from the
simple type of Coriui^piva than that which is produced by the narrowing of the spire as it
crosses each end of its long diameter, — a conclusion which derives additional support from
tlie exact conformity to the Coniuxpiru type, whicli, as already shown (^ 49), is presented bv
the young oi j\liIioIa (see xcvtt, plate ii, figs. 1 — 6).

107. The cliaractcrs adopted by D'Orbignv for the differentiation of his genera are for
the most part furnished by the number of chambers which show themselves externallv : a
variation whicli depends upon the degree in which the later chambers invest the earher, upon
the symmetry of their shape, and upon the mode in which they arc disposed with reference
to the diameter of tlie spire. Thus if the successive segments simply increase in diameter
without departing much from their primitive cylindrical
form, so that the successive chambers of the shell merely
apply themselves to the external surfaces of those which
preceded them, then the whole series of chambers is visible
on each side of the adult slicll ; and the ^fJIUdu which
grows upon this plan, wliicli will be readily understood
from the ideal transverse sections shown in Fig. XV,
is distinguished as Spiroloculina (Plate VI, figs. 1, 2). If,
however, the segments of sarcode extend themselves on
either side into " alar lobes," and these are symmetrically
prolonged so as completely to cover each side of the cham-
bers to which they are applied, as shown in Fig. XVI,
then only in-o chambers — the last and the penultimate —
are visible externally, and we have a Wdoadma (Plato VI. fig. 7).' It often happeu-

FiG. X\

Idi'al transverse sections of Spli'ijloadl-uf.

78

FAMILY MILIOLIDA.

however, that the alar lobes of one side are more prolonged than those of the other, so that
more of the earlier chambers of the shell are shown on the one face than on the other ; in this

Fig. XVII.
A.

B.

C.

Ideal transverse sections of Bilocnlina.

Ideal transverse seel ions of Qiii».queloculina.

way it often comes to pass that fice chambers are visible externally on one side of the shell,
whilst only three are apparent on the other (Fig. XVII) ; and this type is the Quinqudoculina of
D'Orbigny (Plate VI, figs. 3 — G). It is, however, subject to great inconstancy as to the
number of chambers visible externally ; this being usually from fJiree to citjld on one side, and
from lico to (six on the other ; some shells formed on this plan having only tivo chambers visible
on one side and three on the other.* A greater departure from the ordinary mode of growth,
however, is shown by those Miliolm in which the alternation in the direction of the successive
segments of the sarcode-body is not duplex but triplex ; so that the chambers of the shell,
instead of lying on the two sides of the diameter of the spire, cluster around it (so to speak)
triangularly, as shown in Fig. XVIII ; thus causing the shell to become three-sided, and ren-

FiG. XVIII.

Ideal transverse sections of Triloculina.

* It was from having perceived the unimportance of these numerical variations in shells formed
on the plan above described, that Profs. Schultze (xcvii) and Williamson (ex) were led to reunite

GENUS MILIOLA. 79

dering three chambers always visible externally- This is the true Triloculine form (Plate VI,
figs. 13, 14).

108. Now although, if typical specimens only Avere compared, these characters might
well seem to be sufficiently definite to justify the generic differentiations which have been
founded upon them, yet the comparison of extensive suites of specimens brought from
different localities shows that they are subject to an inconstancy whicli altogether destroys
their value. And this inconstancy is readily accounted for, when due allowance is made for
the indefiniteness in the form of the sarcode-body of the animal ; since, as we have seen, it is
dependent upon the degree in which the " alar lobes" of the new segments extend themselves
over the surfaces of the preceding chambers, and on the equality or otherwise of the pro-
longations on the two sides — characters which are extremely liable to variation among
Foraminifera. Of those subordinate departures from the typical form of the segments, whicli
convert their ordinarily rounded outline (Figs. XV, a ; XVI, a, b ; XVII, a ; XVIII, a) into
a carinate or angular contour (Figs. XV, b, c ; XVI, c ; XVII, b, c ; XVIII, b) — differences
on which a vast multitude of specific differentiations have been founded — it can only be here
stated generally that they are subject to the same uncertainty as the larger ones already
disposed of.

109. With such diversities in the form of the chambers are associated corresponding
diversities in that of the apcriure ; which may be elongated laterally so as from a circle tc
become an oval (which is sometimes narrowed into a mere slit), or may approach the form of
a square (Plate VI, figs. 8 — 12, 16 — 33). The shape of the "valve," again, varies with that
of the aperture, and has further variations of its own. In the MUiola cydostoma of Schultze
(xcvii, plate ii, figs. 14, 15), the valve is altogether wanting, and the aperture is quite round.
In the Spirohculina represented in Plate VI, fig. 1, the aperture, shown in fig. 16, has but a
very small projection ; this projection is a httle larger in the specimen represented in fig. 2,
of which the aperture is shown in fig. 17, and is somewhat extended laterally; and in the
QiiinquelocuUna represented in fig. 3, of which the aperture is shown in fig. 18, the valve is
distinctly bifid. In Bilocidlna the usual form of the "valve," as shown in figs. 7, 8, 10, 1 1, 12,
is that of a broad, rounded tongue, springing from the whole of one side of the aperture ; but
in the specimen shown in fig. 9, the valve, still much extended laterally, springs from a nar-
rower base. In figs. 1 9 — 32 is shown a very remarkable series of apertures and valves of a
large MUiola, from specimens brought by Mr. Cuming from the Philippine seas ; of which
variety an example is represented in fig. 33 broken open, so as to show the interior of the
last chamber, and to allow its aperture and valve to be seen from within, whilst the much
smaller aperture and simpler valve of the penultimate chamber are seen from without. This
series is particularly interesting, as showing the wide range of variation that exists in regard
to the form both of the aperture and of the valve, among a number of individuals whicli
must unquestionably be regarded as belonging to the same species ; some of the widest

QmnquelocuUna and TrilocuUna . Neither of them, however, seems to have apprehended the essential
peculiarity of the real Triloculine type to be next described, although this had been correctly pointed
out by M. D'Orbiguy.

80 FAMILY MILIOLIDA.

divergences being presented at the apertures of the successive chambers of one and the same
individual, as seen in fig. 33. In no two are the valves exactly alike in form ; and yet it is
obvious throughout that they are constructed (so to speak) upon the same model. They all
possess, in a more or less developed condition, a vertical plate or keel, which rises fi-om the
median line of the horizontal part of the valve ; and this keel, as is seen in the oblique view
given in fig. 30, frequently forms a sort of arch hollowed beneath like a bridge. In fig. 28
Avill be noticed a remarkable development of two pi'ocesses from the projecting angles of the
aperture, which are seen in a rudimentary condition in several other figures. In fig. 31, the
valve is so much extended horizontally, and the aperture is so unusually contracted, that
what should be the free margin of the valve has come to coalesce completely in one part, and
nearly to do so in another, with an ingrowth from the margin of the aperture ; thus distinctly
tending towards the formation of a complete septum perforated with separate pores, such as
we find in certain other modifications of the 3Iilioline type (•[■[ 110, 111, 118).

1 10. A more remarkable departure from the ordinary type of aperture than any of the
preceding, is presented in the CrucilocuUiw o{ D'Orbignj'; which is a well-marked " triloculine"'
Miliola (fig. 15), of which the aperture has (so 40 speak) four small valves instead of one, a
crucial fissure being left between them. This extreme variety is very rare, being only known
to occur in the coast of Patagonia ; but approaches to it arc met with elsewhere. Another
remarkable departure from the ordinary type of aperture is occasionally found in the well
known " quinqueloculine " Miliola of the Grignon tcrtiarics (the MiHolHe>< mivoriai/ of Lamarck,
the QiniiquelocitHna saxorinii of D'Orbign}'), the \\ alls of whose chambers are often so thick as
to leave but little space for the sarcode-body, which is further encroached on by ridges that
project from their inner surface ; the aperture is much contracted and its " valve "' small ; and
sometimes the internal ridges, coming up into the aperture and coalescing with the valve,
form a cribriform septum that seems to foreshadow that of Faljidaria (to which type this

, variety presents an obvious tendency) and of Peneroplis. We shall presently see that a
more perfectly-developed cribriform aperture is one of the principal features of the sub-
genus Haueriiia.

111. Not less variable in this genus is the surface-marking of the shell ; for, although
normally smooth and sometimes highly polished, it often presents a scabrous aspect, and is
sometimes marked by a more or less regular pattern, formed either by longitudinal ribs as in
Plate "N'l, figs. 3, 4, 33, by transverse plications extending to the interior of the chamber as
in fig. 5, by minute pits arranged in longitudinal series as in fig. 14, by a honey-comb
areolation as in fig. 13, or by various modifications and combinations of these plans. Now
although such well-marked specimens as the four here figured might be reasonably considered,
if taken by themselves, as distinct specific types, yet the comparison of a sufficiently large
number of individuals necessitates the abandonment of any differentiation founded upon the
characters they respectively present ; for it is shown by such comparison that all these kinds
of ornamentation shade off so insensibly into the smooth and pohshed surface of the ordinary
Milioline shell (a specimen which is pitted or ribbed on one part of its surface being often
smooth on another, and this without any appearance of having been subjected to attrition),
that no use can be made of them as specific characters. Thus in the thickest-walled examples

GENUS MILIOLA. 81

of the MUlola m.rormi/ mentioned \n the last paragraph, the external surface is often marked
by extremely deep circular pits ; but these are not usually found on the outer walls of the
earlier chambers of the very same specimens, and a gradational series of specimens may be
easily selected which should show an insensible transition from the most deeply pitted to the
most perfectly smooth individuals. Sometimes the shells of Miliolce, especially of the " trilo-
culine " and " quinqueloculine " varieties, acquire an arenaceous surface (fig. 6) from the
imbedding of grains of sand in the ordinary calcareous substance of the shell previously to
its solidification. These " arenaceous" individuals vary greatly in appearance, according to the
size and character of the particles of the sandy material forming the sea-bottom in their
respective localities.

112. Affinities. — It is obvious from what has been already stated (^ 104), that the
relationship is very close between the least specialized of the " spiroloculine" forms of Miliola
and the ordinary Cormtspira. Again, not only do certain varietal forms of Vertebralina
very closely approximate Mi/iohc in their mode of growth, but Miliola occasionally takes on a
uniserial plan of increase resembling that of Vrrti'hraJina ; so that individuals not unfrcqucntly
present themselves in which the presence or absence of a " valve" is the chief diagnostic
character ; and even this, as we have seen (^ 109), cannot be relied on as a constant differen-
tiation of these two genera. With Feneroplis, again, the Milioline type is connected by a very
interesting modification which has received from D'Orbigny the generic designation Hauerina;
this designation it will be convenient for us to retain as that of a sub-genus of Miliola (with
which it is obviously most intimately connected), without attempting to define the precise degree
of relationship of the two. The real character of Hauerina was completely misapprehended
by D'Orbigny, who, misled by the spirality of its growth (in its early state, at least), placed
it (lxxiii, p. 118) among \\is HelirositY/ucs, between OjjerciiUna and Vertebralina, to the latter
of which it is truly allied, whilst from the former it is separated by as wide an interval
as can exist among any two types of Foraminifera. In the young state of Hauerina, the
cornu^piral form which Miliola generally present in the first instance (^ 106) is retained
longer than usual ; but a distinct division into chambers shows itself in the passage to adult
age ; and as three or (less frequently) four chambers form the circuit of the outer whorls,
the shell has a three- or a four-sided contour (Plate VI, figs. 34, 36). The aperture, like that
occasionally presented by Miliola mxornm, is cribriform (fig. 36, b).* Although described by
M. D'Orbigny as only existing in a fossil state, this type occurs at the present time in the
Indian, Australian, and other tropical and sub-tropical seas. The external surface of its
shell is sometimes smooth, sometimes delicately striated (fig. 36, a) ; whilst sometimes its
walls are very deeply plicated transversely (fig. 35), — a varietal modification of which
we have already seen a less strongly marked example among the ordinary Miliohe (fig. 5).

113. By the Miliola saxoriun, again, the Milioline type is obviously brought into close

* In the description and figure of H. compressa, given by D'Orbigny (lxxiii, p. 119, pi. v,
figs. 26, 27), the septal plane is represented as perforated by a single small, oval aperture, surrounded
by several large, granular elevations ; but these (as appears from the examination of recent specimens
of the same type) really mark the place of passages which have been filled by fossilization.

11

S_> FAMILY MILIOLIDA.

relationship ^vith Fabularia, the pecuharity of whose structure consists in a higher develop-
ment of that tendency to subdivision of the general cavity of each chamber, of which M.
saworuiji presents a rudimentary manifestation. Through T'ahtlaria, again, the Milioline t}'pe
will be seen to be related to AlvcoRna, Orhiculvna, and Orhitolileii, all of which are characterised
by the like subdivision ; and it is most interesting to trace in some forms even of the highly
specialized OrbitoJites a return, as regards the conformation and aspect of the primordial
chamber and of that which immediately succeeds it, to the t}'pe presented by the corre-
sponding portion of an ordinary Miliola.

114. Geographical Distribution. — Probably no Foraminifera are at present more
universally diffused than those of the Milioline type, which are most abundant between the
shore and a depth of 150 fathoms, but occasionally present themselves among the products
brought up from deep-sea soundings. The largest and best developed forms of this tj^pe,
such as that represented in fig. 33, are from the littoral zone of tropical seas. The shell is
itself perfectly free ; but the sarcode body of the animal by which the shell is usually invested
during life attaches itself to sea-weeds, zoophytes, &c., to which Miliola may often be found
adherent.

115. Geological Distribution — The J/?72o/2Me type may be traced back in geological time
as far as the Lias, being rather abundant in the clay of that period from Stockton in
Warwickshire ; it is there, however, very small and delicate, presenting a condition exactly
analogous to that of recent forms brought up from depths of from 350 to 500 fathoms. It is
constantly present in the Gault, retaining its small dimensions, and also in the Chalk marl.
From the upper Chalk to the present period it is everywhere abundant in marine deposits,
having accumulated in certain parts of the Eocene period to such a vast extent that certain
beds of the " calcaire grossier" are almost entirely composed of aggregations of M. saxoruiii,
and are known as "Miliolite limestone."

Genus VIII.— Fabularia (Plate VI, figs. 37,38).

116. History. — The genus Fabularia was first distinguished by Defrance (xxix), who
applied that name to a body having a somewhat bean-like form, which occurs fossil in the
Paris Tertiaries, and which he had pre\aously confounded with Alveolina. He was, however,
totally ignorant of its real nature ; and it is now somewhat amusing to find him suggesting
that, as the irregular pores of its interior could not have contained polypes, it was probably
an internal shell enclosed like the " cuttle-fish bone" in the body of some Mollusk. Its place
as one of the Foraminifera was first indicated by D'Orbigny (lxix) ; but not being then
acquainted with its real structure, he grouped it among his Entomostegues. Subsequently,
however, he was led by more careful inquiry to perceive its essential conformity to the
Milioloid type, and to group it among his Agathistegues (lxxiii) ; and he correctly states that
it is most nearly related to Biloeulina, its difference consisting in this — that the cavity of each

«

GENUS FABULAEIA. 83

chamber, instead of being an empty space, is partly occupied with soUd shell-substance,
which is so disposed as to divide it into a great number of capillary tubes, whilst its aperture,
instead of being single, is made up of numerous minute pores.

117. External Characters. — The general aspect of Fabularia (Plate VI, fig- 37, a, b)
so remarkably resembles that of a gigantic BUumlina, as to occasion some surprise that the
true relationship of this type was not earlier recognised. In fact, it externally differs only in
size, — often attaining a length of 0'24 inch, and a breadth of 0-18 inch, thus far exceeding
the largest Mlliu/ce in dimensions, and in the cribriform character of its aperture, in which
it agrees with //««mH« (f 112). Very commonly, however, the peculiar structure of its
interior is partly disclosed by the abrasion of the surface, which lays open the superficial
series of the longitudinal canals into which it is divided.

118. Infernal Structure. — The internal structure of Fabularia may be made out very
tolerably by the examination of specimens fractured in different directions ; but the most
satisfactory elucidation of it is obtained from thin sections, especially from such as are
carried in a direction transverse to the longitudinal axis (fig. 38). It is there seen that its
general plan of growth is distinctly " biloculine;" the walls of the principal chambers on the
two sides of tlie longitudinal axis meeting each other along the line a b, just as they do in
Fig. XVI, B (p. 78). But the cavities of these chambers, instead of being hollow, are filled up
with sohd shell-substance, which is perforated by channels whose general direction is
longitudinal, though these are often connected, like the Haversian canals of bone, by channels
passing in a transverse or oblique direction. The longitudinal channels are arranged with,
some approach to regularity ; a row of small orifices being observed to lie just within the
external boundary of each chamber, and thus corresponding with the layer of closely
approximated canals which is brought into view when the surface of the shell is removed by
abrasion (fig. 37, a), whilst a much larger set of orifices, less regularly arranged, nearer to the
internal portion of the chamber, shows that the channels are there much wider, but neither so
numerous nor so closely approximated. The whole system of channels, whose mutual
inosculations bring every part of it into the freest communication with the rest, terminates at
the septal plane in a cribriform aperture (fig. 37, b), resembling that which is normal in
Ilaurrina {^^ l\2), and occasional in yI/27zo/« mxoriim (^110). Another curious feature of
relationship to this last variety of the Milioline type is presented in the very deep pitting by
which the external surface of each chamber is not unfrequently marked (fig. 38, b). This
pitting is afterwards filled up by the calcareous deposit which occupies the cavity of the
chamber formed around it ; so that the innermost layer of this deposit comes to be furnished
with a corresponding set of minute tubercles (fig. 38, a), which may be brought into distinct
view by so fracturing a specimen as to separate this layer from the wall of the penultimate
chamber on which it was moulded, and from which it may be commonly detached without
difficulty. The manner in which these pits and tubercles are mutually appUed to one another
(like the pits on the under side of the epidermis to the papillae of the cutis vera), is seen in
section in fig. 38, a', along the line a b.

1 1 9. Affiniticis. — The genus Fabularia may be considered as presenting the culmination

84 FAMILY MILIOLIDA.

of the proper Milioline type of structure ; that subdivision of the chambers^ which we find to
characterise the liighest types of each series of Foraminifera {% 64), being here superinduced
upon tlie simple MilioUnc type of growth. In the existence of that subdivision we have a
relationship of analogy or parallelism to Orbiculina, Orbitolitcs, and Aheolina ; but in plan
of growth Fabularia is so distinctly related to Miliola, that its genetical derivation is
to be looked for rather in the varietal modifications of the last-named type, than in transi-
tional forms connecting it with those just named, which will be found to have (so to speak)
a distinct line of descent.

120. Geological Distribtdion. — The genus Fabidaria is at present only known in a fossil
state, and it has not been met with elsewhere than in the tertiaries of the Paris basin, being
especially abundant at Grignon.

Genus IX. — Peneroplis (Plate VII).

121. Hisfon/. — The germs Peneroplis was first instituted by Montfort (lxvii) to distinguish
a peculiar type of minute polythalaraous shells, which had been previously described and
figured by Schroter (xcvi) and by Fichtel and Moll (xlv), the latter of whom had ranged it
with numerous others under the comprehensi\'e designation JVauHlus. By Montfort its
distinctive character was correctly indicated as " bouche de toute la longueur de la base, et
percee serialement par une file des pores ;" but he seems to have very erroneously inter-
preted the signification of those pores, imagining that the principal chambers are subdivided
into cells, each occupied by a distinct animal, of which cells the pores are the separate orifices.
Lamarck* (lix), not adopting Montfort's genus, referred the Naufilns planafus oi Fichtel and
Moll to the genus Gristellaria, with which it has no relationship whatever ; but the genus
FeneropJis was recognised by Blainville (vi) and by Ehrenberg (xxxix) ; and D'Orbigny has
applied this name, in his various writings on Foraminifera, to the form described by Fichtel
and Moll, whilst he has created one new generic term, Dendritina, for a series of varietal
forms in which there is a single large arborescent aperture instead of a single or multiple row
of separate pores, and another, Spirolina, for a varietal series in which the spire is prolonged
rectilineally into a row of cylindrical or subcylindrical chambers with an aperture resembling
that of BeridrUbia, this last being the Coscinospira of Ehrenberg.

122. External Characters. — The ordinary form of the shell of Peneroplis (of which an
ideal representation given in Plate VII, fig. 18, is an extremely flat spire, of about two
turns and a half, opening out i-apidly in its last half turn. In the young shell each whorl
usually does little more than adhere to the margin of the preceding, so that the first-formed
portion is but slightly concealed by the subsequent growth ; but sometimes the earliest whorl

* The Renidites of Lamarck and the Remdina of Blainville, which are quoted by Prof.
Williamson (ox, p. 44) as synonyms of Peneroplis, are (as already shown, % 98) aberrant forms of
Verteh-alina.

GENUS PENEROPLIS. , 85

is in great degree overlapped by tlic next ; and it very commonly happens that the last half
whorl spreads itself out to such a degree as entirely to invest the preceding, the extension
even reaching so far as not only to conceal the original umbilicus, but even to encroach upon
the opposite half of the spire (fig. 10). When such is the case, however, the extension
is usually limited to one of the lateral surfaces of the shell, which thus becomes unsym-
metrical. Although this extension is sometimes confined to the inner margin of the spire,
as is seen in fig. 16, yet it often occurs along the outer margin also, being usually limited,
however, to the last four or five chambers. The septal plane extends itself in some
instances around as much as three-fourths of the whole margin of the shell ; thus showing,
even in this type, an obvious tendency towards that cyclical mode of growth which we meet
with in Orbicidina, but which is essentiall}^ characteristic of OrbitolUes. The surface of the
shell is highly polished, and has a peculiarly opaque-white, porccllanous aspect. It is very
strongly marked by depressed bands, which indicate the places of the septa between the
chambers ; and between these septal bands the walls of the chambers rise in flattened arches.
In a direction transverse to the septal bands we almost uniformly observe a strongly marked
striation, the stria; running parallel at tolerably regular intervals, which average about
l-1400th of an inch, from one septal band to another; this striation, which imparts a very
characteristic physiognomy to these minute shells, seems due to a sort of plication or ridge
and furrow arrangement of the slielly wall (Plate VII, fig. 20), which may not improbably
have the effect of imparting to it increased strength. The plication generally disappears at
the junction of the walls of the chambers with the septa, and consequently we do not usually
see it at the septal plane when the shell is viewed endways. Sometimes, however, it is con-
tinued on to the septal plane itself; and its character is then extremely well displayed, as in
fig. 15, which, however, represents not the typical form, but one of the varieties to be
hereafter noticed. On the prominences of the plicse, there are frequently to be seen rows of
extremely minute punctations (fig. 20) ; these, however, are not the apertures of passages
through the shell, as might not unnaturally be supposed, but are mere depressions of its surface,
as I have ascertained by the careful examination of veiy thin sections. It is remarkable that
the plication of the shell is sometimes wanting, though the punctations may still present
themselves in rows, as shown in fig. 2 ; whilst, in other cases, not only are the plicEC deficient,
but the punctations are distributed uniformly over the entire surface, as shown in fig. 3.
That these variations are not indicative of any specific difference, is at once proved by the
fact that the shells which exhibit them in one part present the ordinary character of surface
in another. Similar punctations occasionally present themselves on the septal plane of
aberrant forms of the PenerojAls type.

123. The septal plane is perforated by numerous isolated pores, which, in those
extremely compressed specimens that constitute the most typical examples of this generic
form, are arranged in a single linear series (figs. 16, «, 18) ; the number of these pores
depends upon the length of the septal plane, and thus it usually increases with the age
of the individual, each chamber opening externally by a larger number of pores than did that
which preceded it. The typical form of these pores seems to be circular, though they are
apt to present various departures from that shape ; they usually lie in a sort of furrow

36

FAMILY MILIOLIDA.

formed by the projection of the lateral borders of the mouth somewhat beyond the septum,
and each one is suiTOunded by a prominent annulus of shell.

124. Internal Structure. — On examining a thin section of a typical Peneroplis, taken
through the median plane between the lateral surfaces (Fig. XIX), the central chamber is

Fig. XIX.

Section of Peneroplis through the median plane.

seen to have the globose form which characterises the primordial segment of the Fora-
minifera generally ; from this first chamber a sinfjie passar/e leads to the second, which com-
municates in like manner by a single passage with the third, as does the third with the
fourth; the fourth chamber, however, communicates by ^2i?o/iassayes with the fifth, as does
the fifth with the sixth, and the sixth with the seventh. In the septum between the seventh
and the eighth, with which the second whorl may be considered as commencing, there are
three apertures ; and this number continues for the four consecutive partitions which divide the
chambers forming the next half-convolution. Then, however, commences a very remarkable
increase; for whilst in each of the next two partitions there nve/our passages, the numbers
in the four succeeding partitions which divide the chambers completing the second turn are
i-espectively 6, 9, 11, and 14; whilst in the last eight partitions which divide the chambers
of the outer half- whorl, the numbers of the apertures are respectively 14, 20, 2G, 38, 30, 3.5,
44, and 48. The average distance of the apertures from each other remains nearly the same
throughout; so that their number pretty closely corresponds with, and may be taken to
represent, the length of tlic septal plane which they traverse in each case ; and it is not a
little remarkable, that whilst this number should only increase from 1 to 4 in the first
convolution and a half, it should so, rapidly augment from 4 to 48 in the last half-convolution.

12.5. As I have not been fortunate enough to obtain any other than dried specimens of
this organism, I have not had the opportunity of examining the structure and arrangement
of its soft parts. It is obvious, however, that the body of the animal will consist of a series of
compressed, flattened segments, progressively increasing in their transverse diameter, and
communicating with each other by multiple threads or " stolons" of sai'code, the number of

GENUS PENEIIOPLIS. 87

which will augment with the length of the septal plane, whilst through the multiple pores of the
last septal plane the sarcode-body can extend itself into pscudopodia. These may coalesce
at their bases to form a continuous segment, on which a ne\A' chamber will be moulded when
the growth of the body requires such an extension of the shell*

126. Variefk's. — The most frequent departure from the typical form presented by
Fenewjjlis is that represented in fig. 12 ; in which we see that, instead of opening out and
encroaching on the previous whorls, the spire becomes disengaged, and prolongs itself in a
straight hne, its successive chambers exhibiting little or no increase in size. Between this
and the typical form every intermediate gradation presents itself; and it is curious that
even here a transverse extension sometimes takes place, quite suddenly, by a doubling
backwards of the last three or four chambers along the inner margin of the straight portion.
In these elongated varieties of Fencroplis we find the spire less compressed, so that the septal
plane is wider in proportion to its length (fig. 12, a); and this condition, which is also
frequently encountered in specimens that have not thus extended themselves, is almost
always coincident with a duplication in the series of pores in the septal plane. Now, it is not
a little remarkable that this is almost uniformly the case with specimens furnished by
particular localities, whilst those obtained from others not very remote exhibit almost as
uniformly the extremest elongation and narrowing of the septal plane, with only a smgle
row of apertures ; and hence it might not unreasonably be maintained that this difference
should be accounted of specific value. In reply to this, however, there is not only the
analogy of Orbiculina and OrbitoUtes, in which (as we shall hereafter see) an indefinite
multiplication in the rows of inarginal pores may take place during the growth of tlie
individual, but also the fact that in Penerojjlis the two forms cannot be distinguished at an
early age, either by the shape of the shell or by the disposition of the pores, which are often
arranged neither in a single nor in a double row, but on a sort of mixture of both plans, as
shown in figs. 6, a, 10 ; whilst among the more advanced examples of each type it is not at all

* A figure is given by Prof. Elirenberg (xxxis, taf. ii, fig. 1), professing to represent the
decalcified body oi a. PeneropUs obtained alive from the Red Sea, which corresponds with the description
above given in every important particular save this, that the successive segments are connected along
the inner margin of the convolutions by a baud much broader and thicker than the threads which
pass between other parts of the segments ; so that this baud would seem to establish a principal con-
nexion, to which the other threads might be considered as secondary. Now after a very careful
examination both of the septal planes of numerous specimens and of sections taken in the direction of
Fig. XIX, I feel myself justiQed in tlie positive assertion that no such principal aperture exists at the
inner margin of the septum, as would be required to give passage to such a band as is figured by
Prof. Ehrenberg. Consequently I can only account for this feature in his delineation of the animal
(the idea of a difference in the conformation of the shell being negatived by the precise correspondence
between his figures of it and my own, as well as by my familiarity with the Red Sea type of
PeneropUs), by supposing that, like some of his other figures, it rather represents his idea of the
structure of the animal than what he actually saw iu its body, this principal baud being apparently
regarded by him as an intestinal canal by which he supposed all the segments to be connected
together.

88 FAMILY MILIOLTDA.

uncommon to meet with individuals which present i\ combination of the characters of both,
the septal plane having a single row of pores in one part of its length with a double row in
another (sec ex, fig. 85). Sometimes, moreover, in one of the less compressed forms of the
shell, although there is but a single row of pores, it is obvious from their elongated shape
that there is an incipient tendency to duphcation (fig. 8). Hence I consider that it may be
unhesitatingly asserted that the duplication of the row of pores, and the increased turgidity of
the spire which it accompanies, are but features of individual variation, and cannot be
admitted to rank as specific differences ; and in this view I am glad to find myself borne out
by Prof. Williamson, who (ex, p. 44) defines Peneroplis, not (like M. D'Orbigny) as
having only a single row of apertures, but as having " septal orifices scattered over the long,
narrow, septal plane."

127. A much wider departure from tlie typical PcncfopJls, however, is presented by that
group of forms which D'Orbigny has separated under the generic designation iJraiJ^nYzwa;
and according to the usually received notions on the classification of Foraminifera, such a
separation would seem fully justifiable. These forms are especially characterised by the
possession of a single large apei'ture, sending out dendritic ramifications, in each septum
(Plate VII, figs. 1, 14) ; but this is by no means the whole of their differentiation. For the
spire, instead of being compressed, is very turgid (fig. 13); and its successive whorls not
merely surround those which have preceded them, but also invest them with broad alar pro-
longations {al, fig. 14, h, (■), those of the chambers of even the last whorl often extending
neai'ly to the umbilicus. The geographical distribution of Dnidritina, moreover, is peculiar ;
for, so far as I am aware, this type is restricted to tlie tropical ocean. I have not met with
it in dredgings from any part of the Mediterranean or the Red Sea, where Peneroplis
abounds ; while the largest specimens I have seen are those furnished by Mr. Cuming's
Philippine explorations, some of which measure '078 inch in diameter, and '030 between the
lateral surfaces. To such as content themselves with glancing at strongly marked examples
of this type, the propriety of its generic, or at any rate of its sub-generic, separation from
Peneroplis would seem indubitable. Nevertheless I think that I shall be able to show
adequate grounds for the belief that the two forms cannot be separated by any definite line of
demarcation, and that they must therefore be ranked as not merely belonging to the same
genus, but even as varieties of the same species.

128. In the first place, I would refer to the fact that the peculiar plication and puncta-
tion of the surface of the shell, which are such marked features in the physiognomy of
Peneroplis, are repeated in Dendritina (fig. 21) in a manner so precisely similar, as strongly
to impress every one who has his attention directed to the aspects of these two forms
respectively with the idea of their very close relationship. Secondly, we observe in
Dendritina precisely the same tendency to rectilineal extension in the later period of growth
as in Peneroplis; for although the distinct generic term Spirolina has been given to the
form presenting this modification, it is obvious that the example delineated in fig. 4
bears just the same relation to the typical Dendritina, that the one shown in fig. 12 bears
to the typical Peneroplis. The transition from Dendritina to SjnroHna is well seen in fig. 13,
in which we see that the last whorl is just about to disengage itself from the earlier ones.

GENUS PENEROPLIS.

89

and that its continued increase upon the plan which has ah-eady begun to manifest itself
would convert it into a Spirolina. On the other hand, the Spirolina represented in fig. 4
has, up to the time of the substitution of the rectilineal for the spiral mode of growth, all the
characters of an ordinary BendnHna.* Thirdly, the differences of general configuration
between Peneroplis and JDendritina are differences of degree, and present themselves in
very variable amount in different individuals. For, starting from those forms of Peneroplis
in which the spire is least compressed, the transition is easy to those Bendritince whose spire
is least turgid, and whose septal plane is not broader in proportion to its length than it often
is in Peneroplis. From the most compressed forms of Bendritina to those which have the
most turgid spires and the widest septal planes the gradation is insensible, scarcely any two
individuals according in their proportions; thus we find that whilst the septal plane is
sagittate in some (Fig. XX, A, c), it tends to become reniform in others (b, d), the margin of

P'IG. XX.

B c

Front views of four specimens of Dendritina.

the spire, which is almost carinated in the first case, becoming obtuse and even crescentic in
the second. Again, the extent of the investment of the earlier whorls by the latter varies as
much as the degree of turgidity; forwhilst in some of the most compressed forms, as in Peneroplis,
each whorl does little more than apply itself to the margin of the preceding (Fig. XXI, a, c),
the more turgid the spire becomes the more completely (generally speaking) does it embrace
the preceding, the alar prolongations of the chambers thus coming to bear a large proportion
to their principal cavity (Fig. XXI, B, d).

129. Still it may be said that, notwithstanding all these points of resemblance, the
difference between Peneroplis and Bendritina is clearly marked out by the difference in the

* The elegant crozier-like form of Spirolina is sometimes rudely imitated by Lituola , aud

specimens of the latter, the Sp. agglutinans of D'Orbigny (lxxiii, p. 137) for example, have not unfre-

quently been described under the former designation, although the texture of the shell, which is never

arenaceous in Spirolina, and always arenaceous in Lituola, aftbrds a ready aud certain means of

discriminating them.

12

90

FAMILY MILIOLIDA

modes of communication between the chambers of the two types, and that such a difference is
sufficiently important to constitute a vahd generic character. I freely admit that this would
be the case, if the difference were constantly to present itself between all the individuals of the
same type, as it does between their characteristic examples (Plate VII, figs. 13, 16); but the
fact is far otherwise. We have seen that among those which would be unhesitatingly ranked
under the designation Feneroplis, there is not only a tendency to multiplication of the rows of
separate pores, but also an occasional fusion of two or more pores, so as to form a single large
pore of irregular shape. On the other hand, among the unquestioned DeiidritincB we observe
not merely that the form of the single large dendritic aperture is extremely variable, but that
it is frequently so simple as to suggest the idea of having been formed by the coalescence of a
linear series of pores. The highest development of the dendritic form of aperture that I have
met with, is shown in fig. 14, a, b ; two examples of a remarkable departure from this have
just been seen in Fig. XX, b, d, where the proportions of the aperture are altogether
reversed, its breadth being much greater than its length, and its central part being enlarged
at the expense of its ramifications ; while, on the other hand, in Fig. XX, a, c, we have
marked examples of a narrowing and elongation of the aperture, with such a reduction of its
dendritic ramifications that it comes to present little more than a linear fissure. From a
comparison of these cases it will be seen that the form of the aperture bears a pretty constant
relation to that of the septal plane ; the broadest apertures presenting themselves in the
individuals which have the most turgid spire, and the narrowest in those whose spire is most
compressed ; whilst the proportionate development of the two principal alar prolongations
seems related to the degree of that alar extension of the chambers over the whorl they enclose,
of which I have already spoken. But the most satisfactory proof of the wide extent of range
of variation in the form of the aperture in Dendritina, is afforded by a comparative examination
of the apertures connecting different chambers of the same individual. Thus, in the interior
of the very shell (fig. 13) that presented the peculiarly characteristic example represented in
fig. 14, we find a form of aperture closely corresponding to that shown in Fig. XX, c ; and
in four septa of the inner part of another shell we have the simple forms of aperture repre-
sented in Fig. XXI, a, b, c, d.

Fig. XXI.

A. ■ ^ B

Septal planes and apertures from different parts of the same specimen of Dendntitw.

l30. But further, not only do we thus meet with examples of each type which present
more or less of approximation towards the other, but we also not unfrequently encounter

GENUS PENEROPLIS. 91

individuals in which the characters of the two types are so blended as to make it difficult, if
not impossible, to say to which they should be referred. Thus in the specimen (fig. 10)
already referred to as presenting a linear series of pores, the marked elongation of which
shows each to be formed by the coalescence or imperfect separation of two, there is an addi-
tional pair precisely in the situation of the alar prolongations in fig. 14, c ; and it is obvious
that the simple form of dendritic aperture there represented would result from the coalescence
of these pores. along the middle of the septal plane. Another example, also from a young
specimen, is shown in fig. 6 ; and it is readily intelligible how in such a case the subsequent
compression of the spire and the narrowing of the septal plane may cause the pores to
present the simple linear arrangement characteristic of PencropUs ; whilst if, with a
continuance of the early mode of growth, the separate pores of later septa should coalesce
into one aperture, we should have a Bendritina. In another young specimen, shown in
fig. 11, such a fusion of several pores into a single dendritic aperture has actually taken
place («), whilst another broad aperture is seen just below this. Again, in fig. 7 we see the
broad septal plane irregularly perforated by numerous pores, some small and rounded, others
large and irregular, each of the latter being obviously formed by the coalescence or imperfect
separation of two or three ; the turgid spire of Bendritina and the separate pores of Pene-
roplis here coexisting with each other, so as to make it difficult to say to which type the
specimen should be referred. Again, the transition is easy from the specimen represented
in fig. 10 to that shown in fig. 9, and thence to the one whose septal plane is shown in
fig. 15 ; here the coalescence has proceeded so far as to produce a number of separate
branching apertures, and nothing is wanting but the removal of the line of shell which
passes down the middle of the septal plane to unite these into the mo§t characteristic form of
the single ramifying orifice. This individual, like the one represented in fig 13, was already
beginning to assume the Spirolinr form, the rounded shape of the mouth showing that the
spire has detached itself completely from the previously formed convolutions ; in figs. 4, «,
and 5 are shown the septal planes of more advanced examples of the same type, which
present such a combination of the large dendritic apeilure of Bendritina with the isolated
pores of Peneroplis as to complete (in my opinion) the proof that no valid distinction can be
drawn between these two types, either from the number, the isolation, the position, or the
shape of the apertures in the septa. Hence it follows that not merely must the genera
Bendritina and Spirolina be relinquished, but that both these forms must be regarded as mere
varieties of Peneroplis platiafus.

131. Affinities. — A sort of sketching out of Peneroplis may be traced, as we have seen,
in some forms of Nubectdaria (% 90) ; and the type becomes still more defined in Ferte-
hralina, some of whose forms can only be distinguished from Peneroplis by their undivided
aperture. If the elongated sht of the compressed Vertehralince were to be subdivided into
a linear series of pores as in the typical Peneroplis, or the circular aperture of the cylindri-
form variety were to be modified in like manner so as to resemble that of Spirolina, the tran-
sition would be complete. Again, we have seen that an approximation to the Peneropliform
type is presented in the cribriform subdivision of the aperture of a true Miliohi (f 110),
whilst a still closer relationship to it is exhibited in the Hanerine modification of the Milioline
t)rpe (^ 112). Looking to the inconstancy of the aperture in the Peneroplis type itself, we

92 FAMILY MILIOLIDA

can scarcely fail to perceive how slight are the differential characters which separate it from
either Vertehralina or Hauerina. On the other hand, it presents a very close approximation
to the spiral variety of Orbiculina ; a sort of preparation for the subdivision of the chambers
characteristic of that type being made in the subdivision of the aperture, and perhaps also
in the ridge-and-furrow arrangement of the lateral walls of the chambers. And, as we shall
hereafter see {% 143), there are certain aberrant forms of Orbiculina in which the subdivision
of the chambers is wanting, so that no perfectly defined boundary between these two types
can be said to exist.

132. Geographical Distribution. — The genus Peneroplis is very widely diffused through
warmer latitudes, especially frequenting the laminarian zone ; so that few collections of Fora-
minifera from sands or dredgings brought from the Mediterranean, the ^gean Archi-
pelago, the Red Sea, the East or West Indies, the Philippine Seas, or the shores of Australia
or the Polynesian Islands, will fail to present numerous examples of it. A few specimens
have been found on British coasts ; but it seems most probable that, as Prof. Williamson has
suggested (ex, p. 46), these have been brought by the Gulf Stream from the West Indian
Seas. The prevalence of particular modifications seems in some degree determined by
temperature. For it is only in tropical seas that the Dendritine variety presents itself
127); and although the ordinary type also abounds in the same localities, yet it is there
that it shows the greatest tendency towards the dendritine variety, both in the turgidity of
its spire and in the arrangement of its septal pores, whilst the Spiroline variety generally
shows some tendency to the dendritic form of aperture. In the Red Sea the ordinary
Peneroplis is very abundant ; and in its young state the spire is turgid, and its pores are
frequently arranged in a double row or even tend to coalesce, though with each addition to
the number of segments the spire becomes flatter and broader, and in the older specimens
the pores are almost invariably arranged in a single row. Now here the proper Dendritine
variety is either absent altogether, or is extremely rare ; and the Spiroline (which presents
every gradation from the cylindrical to the compressed form) rarely has any other kind of
aperture than a multiplication of separate pores. In the Mediterranean, on the other hand,
which seems to be the most northern limit of its diffusion, not only is the Bendritine variety
altogether wanting, but the Peneroplis type seems (as it were) to be starved out, the spire
presenting the extreme of attenuation, and the septal pores being almost uniformly arranged
from the beginning in a single row. — The Spiroline variety, which is usually of smaller
dimensions, seems to replace both the Dendritine and the Peneroplis type in the deeper waters
of the tropical ocean ; both the large turgid Bendritina and the broad Peneroplides being
inhabitants of comparatively shallow water.

133. Geoloyieal Bistribution. — Neither the ordinary Peneroplis nor its Dendritine and
Spirolme varieties has been traced backwards in geological time further than the commence-
ment of the Tertiary epoch.* The Grignon and Paris Tertiaries contain several forms of

* The statement of some authors that Spirolina occurs in the Cretaceous and even in earlier
formations of the Secondary epoch, has resulted from their having mistaken the crozier-shaped forms
of Lituola for the true Spirolina.

GENUS ORBICULINA. 93

Peneroplis and Spirolina, to the exclusion of Bendritina ; whilst in the Vienna Tcrtiaries we
meet with Dendritinn and Spirolina, to the exclusion of Peneroplis.

GenusX. — Orbiculina (Plate VIII, figs. 1 — 12)

134. History. — The interesting group of organisms belonging to this type seems to

have early attracted notice, probably on account of the great abundance in which it presents

itself on the sands of many of the West Indian shores. Three species are described

and figured by Fichtel and Moll (xlv), under the ^ames oi Nautilus orbictdus, N.anr/ulatus,

and N. aduncm. Lamarck (lix), however, separated them from Nautilus, and raised them

to the rank of an independent genus, to whicii he gave the name of Orbiculina ; and he also

changed two of the specific names, the three standing respectively as 0. numismalis,

0. angulata, and 0. uncinata. By Montfort (lxvii), these species were raised to the rank

of independent genera, under the names of Helenis, Archaias, and Hates ; but these genera

have not been adopted by any other systematist. M. d'Orbigny, in his first classification of

the Foraminifera (lxix), not merely adopted Lamarck's generic designation, but afiirmed

that the three reputed species were really nothing else than one and the same organism in

difi"erent phases of growth, 0. angulata being the youngest, 0. numismalis the next in age, and

0. 7incinata the adult. He arrived at this result, of the truth of which I am myself well

assured, by the comparison of a great number of specimens, a process which it would have

been well for science if he had more constantly adopted. The name of the adult form

should, of course, stand as that of the species; but the organism in question is more commonly

known under the designation Orbiculina adunca, which seems to have been conferred upon it

by M. Deslongchamps (xxxii). A considerable number of figures of this species are given

by M. d'Orbigny in his treatise on the Foraminifera of Cuba (xcii) ; they serve only,

however, to give a general idea of the diversities of external conformation which had

presented themselves to him ; and notwithstanding their number and variety, they do not

include some of the most important among the protean shapes of these bodies, nor do they

throw any light upon their internal structure- The memoir of Prof. Ehrenberg, in which

his group of Bryozoa was originally constituted (xxxix), contains the first recognition of the

near relationship between Orbiculina and Orbifolites, which he grouped in close proximity

among the Bryozoa. His description of their structure, however, is so greatly prejudiced

by his erroneous idea of the nature of the animal body to which they belonged, and is

rendered so imperfect by his want of acquaintance with the appearances presented by their

sections, that it serves rather to mislead than to infoi'm any one who may consult it. It was

by Prof. Williamson (cviii) that the real structure of OrhicuUiia, and its very close conformity

to that of Orbitolites as previously described by myself (xii), were demonstrated ; and that

the frequent exchange of the spiral for the cyclical plan of growth, witli the advance of age,

was recognised ; and the few slight errors into which he fell are probably attributable to the

imperfect state of the specimens on which his description was founded.

94 FAMILY MILIOLIDA.

135. External Characters. — The form under which Orhiculina is most commonly known
is that represented in Plate VIII, figs. 8, 9, 10, which has suggested the specific designation
admica; but such a departure from this as is shown in figs. 1, 2, 3, 4, is not at all infrequent;
and a continuance of the mode of growth which characterises these last sometimes leads to
the assumption of the discoidal form shown in figs. 5, 6, which seems to be the highest phase
of this type, being always presented by the largest specimens of it, some of which attain a
diameter of '20 of an inch. Among young specimens it is not at all uncommon to meet with
some (fig. 2) that bear a strong resemblance in form to Peneroplis ; they are distinguished
from that type, however, by the absence of the striation that so generally characterises it ;
and when the surface-layer of shell is sufiiciently thin, a division of each principal chamber
by secondary partitions passing between the septa at right angles to them may also be very
commonly made out. In older specimens, however, these secondary partitions are seldom to
be seen externally, being usually obscured by the greater thickness of the surface-layer of
shell ; sometimes, however, they continue to be distinguishable even in the most developed
forms (fig. 5). The large discoidal specimens bear so strong a resemblance to Orbitolites as
not to be distinguishable from that type except by the prominence of the umbilical region,
which is occasioned by the investment given by each turn of the spire to the preceding, so
long as the spiral growth continues.

136. The essential unity which prevails through these and other less important diversi-
ties will be understood by following the growth of Orhiculina from that early condition
shown in fig. 7, which is common to all. Its form is then lenticular, or even, in the thicker
varieties, almost orbicular ; each septal band, commencing from the centre (a) of the spire,
goes off, in the first instance, in such a manner as to encroach on the opposite side of the con-
volution; it then curves round with a strong convexity directed forwards {h), turns back,
and finally terminates at the margin (r) in such a manner as to form its continuation. By
this curvature the septal plane («, h, c), which, as yet, corresponds to only half the diameter of
the spire, is greatly elongated, so as to present a much larger apertural surface than it would
possess if it passed directly from the centre to the margin in the line a r. When viewed on its
anterior face, it has the form of that of a PeiieropJis whose spire completely invests the
preceding; its breadth varying in proportion to its length, as the shell is orbicular or lenticular
in shape, but its alar lobes being always much prolonged. Its entire surface is perforated with
pores exactly resembling those of Peneroplis, each being surrounded by a prominent annulus
of shell ; and these pores show some definitcness of arrangement, being disposed in
more or less regular rows, as to the number of which, however, there is no constancy
whatever. In a more advanced stage of growth (fig. 8), we see that the septal band,
still commencing at the centre («), and partly encroaching on the opposite side of the
spire, then bends round as before ; but instead of speedily turning backwards, it makes
a gentle curve [h], which forms a large part of the margin of the shell, and then
terminates abruptly at c, this termination being the source of the " aduncal" form.
Here we see that the septal plane with its apertural surface is greatly extended ; and along
all that portion of it which forms the margin of the shell, the pores are disposed with more
approach to regularity, the number of rows, however, being very variable. In a yet more
advanced stage of the " aduncal type," the later portion of the spire ceases to invest the

GENUS ORBICULINA. 95

earlier, the newest chambers stopping short at its margin or but slightly encroaching on it
(fig. 9, a) ; and the septal plane, which now forms from, two-thirds to three-fourths of the
entire circuit, is much narrower in proportion to its augmented length, more resembling that
of an advanced Fencrojj/ia {VMc VII, fig. IG, f/), but usually showing multiple rows of pores.
This mode of increase may continue during the whole life of any individual, so that speci-
mens attaining a diameter of -12 of an inch not unfrequently preserve the " aduncal" shape.
But it often happens that the outer extremity of the newly formed chambers (fig. 4, <••), instead
of abruptly terminating at the most anterior part of the margin, extends itself by an inward
curvature, so as to double back upon the earlier portion of the spire, and thus to approximate
the inner extremity of the same chamber (fig. 4, «) ; and the septal plane with its apertural
surface is thus carried round nearly the entire circuit of the shell. A persistence in the
same plan of growth causes the two extremities of the chambers to meet and completely
. to surround the original spiral (fig. 5) ; and from that time forth each new chamber forms a
complete and continuous ring around the preceding, and the apertural surface of the septal
plane extends round the entire circuit. In the most advanced stage of its growth, the disk
often thins out to such a degree that the apertural margin is no broader than that of a
Feneroji/is, and has, like it, only a single row of pores.

137. Now this change from the s/jiral to the cyclical plan of growth may take place at
any period of life. In the individuals represented in figs. 1 and 3 there is obviously a
preparation for it ; these showing no tendency to that abrupt termination of the outer ends of
the later chambers which gives rise to the " aduncal" form, but, on the other hand, exhibiting
a marked disposition to the extension of these towards their inner extremities, so that they
will assume the discoidal form without passing through what is usually the intermediate
stage. Hence it is impossible to regard it in any other light than as a varietal modification,
the conditions of which are as yet unknown, though related in some degree to the advance
of age.

138. The shell of Orhmdina corresponds closel)^ in texture with that of Peneroplis,
having (in well-preserved specimens) very much of the same polish and enamel-like lustre.
Its surface is frequently marked (like that of the Miliola) by pits which present the semblance
of pores, and which have been mistaken for them by Prof. Williamson (cviii). A careful
examination of thin sections, however, makes it clear that the continuity of the shelly wall is
nowhere interrupted.

139. Internal Slructurc. — In a large proportion of ordinary specimens of Orhicidina
the natural surface has been so far removed by abrasion as in some degree to disclose the
internal structure of the shell ; this, however, is much better displayed by thin sections
carried through the median plane, such as those represented in figs. 6, 10, 11, and by sections
taken at right angles to this, such as that represented in fig. 12. An idea of the structure
will be best formed by supposing each elongated galler}'' which forms the chamber of a
Penerojjlis to be partially subdivided into " chamberlets" (if the coinage of such a diminu-
tive be admissible) by a series of partitions that pass transversely from each septum to the

96 FAMILY MILIOLIDA.

next ; all the " chamberlets" of the same row, however, communicating with each other by
a passage that runs continuously through their partitions (see Diagram, p. 52) ; and each
" chamherlet " also communicating with the chamberlets of the adjacent rows by perforations
in the principal septa. This is, in fact, exactly what we see in the peripheral portion of
those thinned-out specimens of discoidal Orbicidince which have but a single row of marginal
pores, as will be clearly understood from fig. 1 1 , which represents a part taken from the
edge of fig. 6, seen as an opaque object under a much higher magnifying power. At
na', ad , ad, ad are seen portions of four of the principal septa which separate from each other
the principal chambers or galleries cc', cc', re' ; these galleries are again divided into the
" chamberlets " d, d, d by the secondary partitions e, e, e, e, which do not, however, com-
pletely separate them from each other ; and the successive galleries communicate with each
other by the passages I/, b, that traverse the principal septa, those of the last-formed septum
showing themselves as a row of pores upon its external surface. The animal body which
occupies the interior of a shell thus divided will obviously consist (as we shall see to be the
case in Orlitolites (Plate IV, figs. 14, 23) of a series of principal segments of sarcode, each
of which is divided by constrictions into a necklace-like series of sub-segments, strung
(as it were) upon a connecting cord ; whilst each principal segment will communicate with
the segments anterior and posterior to it, as in Peneroplis, by stolons of sarcode that pass
through the septal passages, those of the last segment issuing forth as pseudopodia from the
marginal pores.

140. It is seldom, however, that the arrangement is so simple as in the case just cited;
for it much more frequently happens that the space between the two surfaces of the shell
exceeds by many times the distance between each septum and that which succeeds it, so that
the " chamberlets '' are greatly elongated in the direction perpendicular to the surface. This
is shown in fig. 12, which represents the central portion of a section whose plane passes
at right angles to that of the spire, and brings into view the successive convolutions 1, 2 2',
•3 3' and 4 4', of which each is seen completely to enclose the preceding. Each " chamherlet "
is here elongated vertically, and the adjacent " chamberlets " of the same series communicate
with one another, not by one passage, but by many (a) ; whilst the successive series also
communicate with each other by multiple rows of septal pores {b). In neither set of communica-
tions, however, do we observe any great regularity, whether as regards number or arrange-
ment. The height of the chambers, with the number of the connecting passages proceeding
from them in each direction, is seen to increase progressively from the first-formed convolu-
tion (1), whose chambers are disposed upon the simple type previously described, through
the second (2 2') and third (3 3') to the fourth (4 4'), in which last it reaches its maximum at
no great distance from the centre ; and from this it often diminishes as the chambers
extend themselves more and more widely along the margin, which (as already stated) may thin

out until we find in the peripheral portion a recurrence to the simple type of the central

The disposition of the sarcode-body that occupies this more complex system of chambers
must obviously be modified in correspondence with it, as we shall see in the complex form of
OrbitdUfcs (Plate IV, fig. 25). The subdivisions of each principal segment, instead of resembling
beads strung upon a single cord, will rather have the form of a row of columns standing side
by side, and connected together by numerous bands passing transversely from one to the

GENUS ORBICULINA. 97

other ; whilst similar multiple bands pass from each series to the rows that stand behind and
in front of it,

141. A comparison of figs. 6 and 10, — of which the former represents the internal
arrangement of the cyclical type, and the latter that of the aduncal, — shows that the early-
growth of the former, up to the period when the mouth of the spire widens out on both sides,
takes place after precisely the same fashion as that of the latter ; after which the aduncal
termination is concealed by the extensions of the subsequently formed chambers along its
margin, which extensions, having once advanced far enough to meet those advancing in
the opposite direction, unite with them, so that each gallery of " chamberlets " thenceforth
returns into itself, instead of terminating by two blind extremities. A conception of the
probable mode in which the successive additions are made to the shell will help us to under-
stand how the one mode of growth may be exchanged for the other, without any departure
from the fundamental plan. The extensions of the sarcode-body which form the pseudo-
podia issuing from the marginal pores will first coalesce with each other at their bases, so as
to form a continuous segment which will lie along the external surface of the last septum ;
if this segment were of uniform size along its whole length, the shelly chamber formed by
the calcification of its surface-layer would be simple, like that of Peneroplis ; but it is thick-
ened in front of each septal pore, and narrowed in the intervals between these thickenings,
so as to form a series of secondary segments united by a continuous stolon ; and the shelly
envelope moulded upon this will have a corresponding series of " chamberlets " connected by
a continuous gallery. Now the tendency of each new segment of the sarcode-body is usually to
extend itself along the margin beyond the preceding; but this extension is commonly limited
in the early growth of Orhkulina to the inner extremities of the successive segments, which
gradually creep round the earlier portion of the spire, whilst their outer extremities terminate
abruptly, and may continue so to do through the whole of life. But if these outer extremities
of the segments of sarcode should share in the extension, they will creep along the margin
of the older part of the shell in the contrary direction, until they meet and coalesce with
those of the inner extremities ; and from that time each successive segment of sarcode will
be a complete ring which will encircle the entire margin of the disk, and the successive
additions made to the shell will be formed upon the cyclical plan.

142. A larger size and higher development are attained by some fossil forms of
OrbicuHna, which there is nevertheless no sufficient ground for regarding as specifically
different from the existing type. Under the erroneous designation of Orbitolites Malabarica,
Mr. Carter has described (xx) a species of OrbicuUna that abounds in a Tertiary hmestone
apparently corresponding with the Nummulitic limestone of the South of Europe ; and of
this species I have, through his kindness, had the opportunity of carefully examining several
examples. In size it greatly exceeds the existing type, its diameter being sometimes as much
as seven or even eight lines ; in general structure, however, it altogether conforms to the
description already given, with this one exception, that each surface is formed (as in the
complex type of Orbifolitcv) by a layer of shallow chambers that are partially cut ofi" from
those of the thick intermediate substance. This difference, however, possesses no greater
claim to be accounted a specific distinction in OrbicuHna than it does in OrbiloUtes ; and since,

13

98 FAMILY MILIOLIDA.

when we come to examine into its value in the latter type, we shall there find it to be a mere
varietal or developmental diversity, it cannot here be accepted as of higher value.

143. Affinities. — The genus we have been considering occupies a position precisely
intermediate between PeneropKs and Orbitolifes, to both which types it is most intimately
related. As already mentioned, young specimens of Orhiadina are often to be met with
which bear a very strong external resemblance to Pcnerojilis ; and even the absence in the
former of the striation usually characteristic of the latter does not furnish an absolute ground
of differentiation, since the striation is not unfrequently obsolete in Peneroplis (f 122). In
ordinary cases, however, the difference becomes evident so soon as we examine into the inter-
nal structure of Orliculina ; being marked by the subdivision of the principal chambers into
" chamberlets " by the partitions which extend transversely between the septa. It is a fact
of not a little significance, however, that those partitions are sometimes wanting, not merely
in feebly developed peneropliform varieties, but even in good-sized adunciform specimens ;
so that the chambers are formed upon the model of those of Peneroplis, and must be occu-
pied, as in that genus, by transversely elongated lobes of sarcode, instead of by a monUiform
series of sub-segments. In such cases, therefore, no absolute line of demarcation can be laid
down between Peneroplis and Orbicidina ; for, although there may be practically little or no
difliculty in referring any given specimen to one or the other type, by the aggregate of the
characters it presents, yet no one of these characters taken by itself is sufficiently constant
to serve as the basis for a precise definition. So, on the other side, the resemblance between
the peripheral portion of an OrbicuKna that has taken on the cyclical growth, and the
corresponding portion of those varieties of Orbitolites in which the superficial chambers are
not differentiated from those of the intermediate stratum (^ 173), is so extremely close, as
well in internal structure as in external aspect, that the two could not be distinguished by
anv character or combination of characters. It is, in fact, only in their early mode of growth
that Orbicidina axidi Orbitolites essentially differ from each other; the former being always
spiral, whilst the latter is ti/jjicalli/ cjcYicdX from its commencement. But we shall see (^ 180)
that the early growth of Orbitolites is often spiral ; and the difference between the two types
seems to resolve itself essentially into this, that the spiral mods of growth gives place to the
cyclical in Orbitolites before a second convolution is formed, so that the primordial chamber
and the first convolution are never invested by subsequent growths.

144. Geo(/rapJtical Distribution. — This generic t3^pe appears to be limited to the warmer
parts of the ocean. It is found in great abundance near the shores of the West Indian
Islands, also near those of the islands of the East Indian and Polynesian Seas, being especially
large and abundant in the neighbourhood of the Philippine Islands. It occurs also in the Red
Sea, and is asserted to present itself in some parts of the Mediterranean and in the ^gean,
though it is certainly not a common inhabitant of those seas. So far as is at present
known, Orbicidina is entirely deficient in the seas of colder latitudes.

145. Geological Distribution. — We have at present no certain knowledge of the existence
of Orbicidina in any formation anterior to the Tertiary series ; but in several members of this
it is very abundant. A fossil form closely resembling that of the Malabar Limestone has been

GENUS ALVEOLINA. 99

found in the Tertiarics of St. Domingo ; and the type is also found fossil in a white
(Tertiary ?) limestone at Corfu.

Gejius IX.— Alveolina (Plate VIII, figs. 13—15).

146. Histori/. — Most of the examples of this type at present known are fossils, occurring
in association with Nuutiutilites, Orhltolites, &c. in the Nummulitic limestone, or in other
formations which represent it ; and those first described (by Fortis) were confounded with
Nummulites and Orbitolites under the term Discolithus. By Fichtel and Moll (xlv) they were
ranked as a sub- type of their comprehensive genus Nautilus. The designation Alveolites was
first given to this type by Bosc,* who erroneously referred two minute forms of it to a genus
which had been previously established by Lamarck (lvii) for a group of corals ; but Montfort,
(lxvii), not accepting this determination, raised three of Bosc's species to the rank of genera,
under the names of Borelis, Clausulus, and Miliolites. Lamarck did not adopt either Bosc's
or Montfort's generic designations, but substituted new ones (lix, lx), Melonites for the fossil,
and Melonia for the recent forms. Defrance (xxix) proposed yet another. name, Ori-aria.
And finally M. D'Orbigny (lxix) adopted Bosc's name, with a slight alteration in its termi-
nation, which served at the same time to mark the continued existence of the type, and to
distinguish it from the Lamarckian genus of Corals. The name Alveolina was soon afterwards
adopted by M. Deshayes (xxx), and it may now be considered as the established designation
of the genus, the synonymy of which has recently been very fully treated by Messrs.
W. K. Parker and Rupert Jones (Lxxxa).

147. External Characters.- — The recent specimens upon which my investigations have
been made belong to a fusiform variety which was tolerably abundant both in Mr. Jukes's
Australian dredgings, and in Mr. Cuming's Philippine collection ; they were obviously identical
specifically, but those from the latter source considerably exceeded those from the former in
average size. The length of the longest complete specimen in my possession is '35 of an
inch ; but I have a specimen whose shape is nearly cylindrical (the A. Quoii of D'Orbigny),
which, though incomplete at one end, measures "50 of an inch. The ordinary form, from
which any considerable departure is very rare, is that which is exhibited in Plate VIII, fig. 13;
and it is obviously produced, as correctly stated by M. D'Orbigny, by the involution of a
spiral around an elongated axis. The surface is marked out by depressed septal bands into
a succession of segments of tolerably uniform breadth ; and each of these segments is crossed
by secondary furrows, which lie so closely together as to mark out each into a series of very
elongated areolae, that remind us of the oblong superficial areolae of the complex type of
Orbitolites (Plate IX, fig. 7), but are much narrower in proportion to their length. The
apertural plane of the spire is closed by a solid wall, the surface of which is nearly flat, and

* 'Bulletin des Seances de la Societe Philomathique,' No. CI.

100 FAMILY MILIOLIDA.

which is perforated by multiple rows of rounded pores, each surrounded by a prominent
annulus of shell, and bearing a very close resemblance to the pores at the margin of OrbicnJina
and Orbifolites. One such row is pretty uniformly to be made out at the inner border of each
apertural plane ; and another row of very small pores, closely set together, may be detected
in well-preserved specimens along the outer border. The apertural surface increases con-
siderably in breadth towards its two extremities, and the rows of pores are there more
numerous but less regular.

148. Internal Structure. — The internal structure of AJveoVma will be best understood by
supposing the cavity of an Oliva (or any other univalve shell that winds spirally round an
elongated axis) to be crossed not only by transverse partitions, which divide it into principal
chambers (indicated on the surface by the depressed septal bands that run parallel to the
axis), but also by a set of partitions at right angles to these, which divide each principal
chamber vertically into a row of long, narrow " chamberlets" in lateral contiguity with each
other, these secondary septa corresponding with the secondary furrows of the surface
(Fig. XXII). The chamberlets thus divided will open at the apertural plane by a single row

Fig. XXII.

Simple type of Alveoliim, as seen laid open at a, and in transverse section at B. At c is shown a portion of tlio apertural
plane of a specimen which exhibited two rows of pores ; and at d, a transverse section of one of the septa.

of pores resembling that which is characteristic of Peneroplis. It may occasionally be noticed,
however, that the septal pores form a double row, as shown at c ; in which case those
nearest the e.Kterior are directed towards the longitudinal canal, as is seen in section at D, a,
so as to establish a direct communication between each segment and the longitudinal
stolon from which the next appears to commence. Such is, in fact, the structure of all
the fossil Alvoolina I have examined ; and we may characterise it as that of the si'wple
type of Aheolina. — In the recent form which I have specially studied, however, the structure
is much more complex ; for each principal chamber is subdivided not only by vertical, but
also by horizontal partitions or floors, so as to form a succession of " storeys," which are
indicated externally by the multiplication of the rows of pores on the apertural plane. This
will be partly understood from Plate VIII, fig. 15, which represents a section of Aheolina
taken in the direction of its elongated axis, and which shows the general mode of increase by
successive convolutions around the primitive spheroidal chamber, each convolution extend-
ing considerably in a longitudinal direction beyond its predecessor, and thus adding much

GENUS ALVEOLINA. 101

more to the length than to the diameter of the shell. In this section the long narrow
chamberlets are divided transversely, so that they are merely seen as rows of rounded aper-
tures channelled out in the solid substance of the shell ; they correspond in relative situation
with the pores of the apertural plane, but are usually of much larger size. Generally about
four such rows may be distinguished in each convolution ; but they are far from being
regularly disposed, especially towards the two extremities of the axis of growth. Along the
outer margin of the last and of each preceding segment, we see a row of apertures much
smaller than the rest, and much more closely set together ; these are the transverse sections of
tlie superficial layer of chamberlets, the dimensions of which are indicated by the furrowing
of the surface, and which are about twice as numerous as those of the rows that lie internally
to them. This difference is peculiarly interesting when taken in connection, on the one hand,
with that which we have seen to exist between the superficial and the more deeply seated cham-
berlets of Fabularia (f 118), and on the other with that which we shall encounter between
the superficial and the intermediate" layers of chamberlets in OrbitoUfes (1 16G), the type in which
this differentiation seems to acquire its fullest development. The form and arrangement of
the chamberlets are better displayed by transverse sections of the shell, such as is represented
in fig. 14; in which figure the solid substance is left white, the shallow cavities occupied by
the sarcode (here laid open in the direction of their length) are shaded of a half tint, whilst
the black spots represent the openings of long galleries that pass continuously from one end
of the shell to the other, so as to bring all the chamberlets into free communication with each
other laterally. As each whorl is in regard to all essential particulars but a repetition of the
rest, it will be sufficient to describe the structure of the outer convolution. This is divided
into principal segments, which obviously correspond with the spaces that intervene between the
depressed septal bands of the external surface ; the places of those bands being marked, not
only by slight inflections of the external outline, but also by prolongations [a, a, a) of the
superficial lamella, which are directed inwards so as to contract the mouth of the spire at
what may be considered the termination of each formative act. Just within these projections
are seen the orifices [b, b, b) of one set of longitudinal channels, whilst nearer the internal side
of the convolution are seen the orifices {c,c, c) of another much larger series of longitudinal
channels, which are like galleries connecting the contiguous chamberlets of the same floors.
Between the orifices b, h, b, and the orifices c, c, c, which respectively correspond to them,
there is no division of the principal cavity of the spire into " storeys" of chamberlets ; but, to
carry out the analogy, those intervening spaces may be likened to the well-staircases by
which a vertical communication is established between the several " storeys" in a large
mansion. The principal cavity of each segment is elsewhere separated by the intervention of
three concentric laminae of shell {d, d^, d^) into a set of superposed chamberlets {e, e^, e^, e'),
which are usually four in number, though in a portion of the convolution that is rather narrower
than the rest we see only two lamellse and three chamberlets, whilst in a wider portion of
the interior convolution we see four lamellae and five chamberlets, and even this number is
frequently exceeded. The thickness of these lamellae is by no means uniform, and the capacity
of the chamberlets between which they intervene is subject to variation accordingly.
Generally speaking, the lamellae are thickest at their posterior extremities, so that the entrances
to the chamberlets from the vertical " wells" are there much narrowed ; in front of these
constrictions the cavities of the chamberlets usually open out considerably ; and they become

102

FAMILY MILIOLIDA.

narrower again towards their anterior extremities, where their terminations appear as the
pores on the apertural- plane whicli closes in each segment as its formation is completed.

149- The idea of the structure of the composite animal which we gain from the
examination of these sections of the shell is fully borne out by the examination of the
silicified " casts " of the interior, which Messrs. Parker and Rupert Jones have been fortunate
enough to obtain (p. 10) ; for these casts, which exactly represent the form of the sarcode-body
whose place they have occupied, exhibit just the arrangement and connections which might
have been predicated. The whole body (Fig. XXIII) is made up of a series of minute elongated
sub-segments, united together at their extremities, in the mode to be presently described, into
groups which represent the principal segments of Foraminifera of less complex type. Every
such group consists of several rows (usually four or more) of sub-segments, arranged vertically

Fig. XXIII.

Portion of an Internal Cast of an Alveolim of complex type -.—a, a, a, a, superficial series of sub-segments ;
b, I, b, subjacent series ; cc, cc, longitudinal stolons ; d, d, vertical columns.

one over the other ; but the sub-segments {a, a) forming the superficial layer are of only about
half the breadth of those [b, h) of the subjacent layer, and are about twice as numerous. The
superficial sub-segments spring by slender peduncles from a band or " stolon" (c, c) that passes in
a longitudinal direction from one end of the series to the other, and terminate at their anterior
extremity in a similar band. The sub-segments that form the subjacent layers spring
posteriorly by constricted necks from vertical " columns " {d, d) which occupy the " well-stair-
cases," and terminate anteriorly in similar columns ; and the columns forming each of the rows
that intervene between one segment and another are brought into lateral connection by two
or more " stolons " which pass along the entire series. Thus although the sub-segments
themselves have no direct communication with each other, they are intimately united into
one system by the intervention of these " columns " and " stolons." Looking to the place
of the connecting passages in the transverse section (fig. 14), it becomes obvious that the
stolons which occupy them are formed by the union of the pseudopodial extensions that
issue from the pores of the aperture. A coalescence of those proceeding from the four sets
of pores (one of them close to the inner margin of the spire) corresponding to each other

GENUS ALVEOLINA. 103

vertically along the septal plane in fig. 13, would establish what I have termed the "columns"
which seem to constitute the first-formed portion of a new segment ; a lateral coalescence of
these columns at tolerably regular intervals would establish the longitudinal " stolons ;" and the
formation of solid shell between these columns and stolons would leave them in occupation
of the two sets of communications that have been designated as the " well-staircases " and
the " horizontal galleries." The further development of the segment will consist in the
anterior extension from each " column" of a set of sub-segments of sarcode separated from each
other both vertically and horizontally by partitions of shell ; and the extremities of these will
appear, when the growth of the segment is completed, at the apertural pores, where they will
be again connected through the coalescence of their extensions, so as to form vertical
" columns" and longitudinal " stolons."

150. Varieties. — The foregoing plan of structure may be traced, with or without
modification, through a series of extinct forms which presents a wide range of variation in
shape, and which closely approximates at one extremity to that of Orbiculina. Thus the
(so-called) Orbiculina rofella of D'Orbigny (lxxiii, p. 140), notwithstanding its nautiloid
discoidal form, seems pretty certainly to belong rather to the Alveoline than to the Orbiculine
type of structure ; from this the transition is by no means abrupt to the oblately spheroidal
and thence to the spherical varieties of Alveolina melo, which is a very common fossil of the
early Tertiary Limestones both of the Continent of Europe and of India. From its spherical
we pass to its prolately spheroidal forms, and thence to its ovoidal (the A. ovoidea of
D'Orbigny), some of which last attain enormous dimensions, specimens being not unfrequent
in the Tertiary Limestones of Scinde whose length reaches three inches and whose diameter is
an inch and a half. A still greater elongation of the axis, with attenuation towards the extremities,
gives the fusiform shape of the A. Boscii, a variety which is common in the Paris Tertiaries,
and which bears a strong external resemblance to the one at present existing in tropical seas ;
and it is clear that the yet more elongated sub-cylindrical forms presented by A. elongata and
A. Quoii, of which the former is fossil and the latter recent, are nothing else than a result of
the tendency to elongation of the axis carried out to a still greater extent. There is, however,
an important difference in internal structure between the entire series of fossil forms and most
of their existing representatives ; for although the external aspects are so nearly identical in
certain specimens that they are only distinguishable by the difference in the number of rows
of pores in their septal planes, and although the general plan of the fossil is exactly con-
formable to that of the recent, yet that plan seems to be uniformly worked out in fossil
forms, however large may be their dimensions, upon the " simple" plan, the " complex"
being only met with in the type at present inhabiting equatorial seas. Noyv this
difference, being apparently well marked and constant, would obviously be entitled to rank
as of specific value ; if we did not find in Orbitolites, to which Alveolina is closely allied in
general plan of structure, that a difference of an exactly parallel character between what will
be there termed the " simple " and the " complex " types must be reduced to the grade of a
mere varietal modification, since the passage from the former to the latter is frequently
presented in one and the same individual.*

* It seems requisite for me to state, that I fiud myself unable to admit the existence of any

104 FAMILY MILIOLIDA.

151. JJfbnlic-^. — It will be obvious from what has preceded, that notwithstanding the
apparently wide interval which separates the typical Alveolina from its congeners, it has a
strong analogy both to Orhiculina and to Fabularia in its general plan of structure. Its
closest affinity, however, is evidently to the regularly spiral type of Orbiculina, since we find
in it no trace of that Milioline plan of growth which so remarkably characterises Fabularia.
It has been already pointed out that Orbiculina essentially differs from OrbitoUtes in the
investment of the first-formed convolutions by the latter, so that its umbilical region becomes
prominent instead of being depressed, and its spire coils round an axis instead of round a
point ; and, by tlie gradation which has been just shown to have an actual existence, the
progressive elongation of the axis round which the spire revolves converts the flattened
lenticular spiral of the J. rofella into the almost cylindrical volution of A. elonyata. The
difference in shape, in fact, is not nearly so great between Orbiculina adunca and A. roiella
as it is between A. rotella and A. ehnyata ; but it requires an examination which I have not
yet had the opportunity of making into the internal structure of A. rotella, to enable me to
affirm with certainty that the transition which it so obviously presents to the Orbicuhne
type in its external form extends also to its plan of growth.

152. Geographical Bidribufion. — The recent examples of this type are limited, so far as
we at present know, to the seas of tropical or southern temperate regions ; the larger
fusiform and cylindrical forms having been chiefly brought from the shores of New Holland
and of the Philippine Islands in the eastern hemisphere, and from those of Cuba and the
Antilles in the western ; whilst a small spheroidal variety, which appears to belong to the
simple type, is figured by Ehrenberg (xlii, pi. xxxvii, 10, fig. 1, a—f) from the Adriatic.

153. Geological Distribution. — The extinct forms of Alveolina belong for the most part
to the formations coeval with the Nummulitic Limestone ; and they present themselves in
various proportions, sometimes so abundantly as almost of themselves to make up the
substance of the deposit, in the early Tertiaries of Paris, Bordeaux, the Pyrenees, and
Austria, as also in those of Persia and Northern India (xix, xxi). One species is stated by
D'Orbigny (lxxiii, p. 145) to present itself in tlie Turonian or Lower Chalk formation at
the mouth of the Gironde, although none has been hitherto met with in any part of the
Senonian or Upper Chalk.*

" canaliferous system " in Alveolina ; and that the appearances which have been interpreted by
Mr. Carter (xxi) as indicative of its presence in the fossil Alveolina of Scinde are quite comforma'ble
with the account of its structure which I liave given on the basis of a very careful examination of that
of its recent analogue.

* I cannot agree with ray friends, Messrs. Parker and Kupert Jones (lxxx a), in referring tlie
Palffiozoic Fusulina to this type ; for although the metamorphic condition of the shell, in all the
specimens 1 have examined, forbids my speaking with full assurance, yet the appearance presented by
thin sections is such as to leave scarcely any doubt in my mind that its structure was tubular, and
that it consequently holds somewhat the same place in the hyaline series that Alveolina does ip the
porcellanotis .

GENUS ORBITOLITES. 105

Genus X. — Orbitolites (Plate IX).

154. Ilistori/. — The Orbitolile has been chiefly known, until very recently, rather by its
fossil than by its existing forms. The abundant occurrence of its disks in the ' Calcaire
grossier ' of the Paris basin early attracted attention ; but Orbitolites were not clearly distin-
guished by the older observers from Nummulites, and their true nature was entirely misun-
derstood. Thus we find them designated, often in association with Nummulites, under the
title of UmbiUcus marinm by Plancus (lxxxiii), who imagined them to be opercula of
Ammonites ; of Porpitce nummulares by Stobaeus and Bromell, who seem to have regarded
them as representing the disks of the existing Porpitae ; of Helicilcs and Operculites by
Guettard, who considered them as opercula of Gasteropods ; of BiscolUhi by Fortis, who
supposed them to be skeletons of Mollusks ; of Madreporites by Deluc, and of MiJleporites
by Faujas de St. Fond, whose idea of their nature is sufliciently indicated by the names they
assigned to them. (See i, § i.) The genus Orbitolites seems first to have been erected on
the type of the 0. coMplanafa of the Paris basin, and to have been differentiated from
Nummulites, by Lamarck (lviiJ, who ranked it between Lmmlites and Millepora, among his
" Polypiers Foramines." He subsequently (lx) altered the name from Orbitolites to Orbic-
Hies ; but the latter designation having been previously employed in Malacology, the first
appellation was restored by M. Milne Edwards in his posthumous edition of Lamarck's
work. Under one of the designations Orbilolites or Orbulites, the genus has been gene-
rally recognised by systematists (xiii) ; none of them, however, have either given any
account of its internal structure, or made any essential modification in the definition of the
genus ; and they all left it in the place which Lamarck had assigned to it, until after the
appearance of my own description of the microscopic structure of Orbitolites (xii), in which
I showed its identity with the recent Australian Maryinopora of MM. Quoy and Gaimard,
and of the subsequent memoir by Prof. Williamson (cviii), in which the Foraminiferous
character of this type w'as proved by the close conformity of its plan of organization to
that of Orbicnlina* It was not until the publication of his ' Cours Elementaire' (lxxiv)
in 18.52, that M. D'Orbigny admitted this genus into his systematic arrangement of Fora-
minifera ; the order Cyclostjigues, in which it is associated with Cyclolina (which I believe
to be only a variety of Orbitolites), with OrbiloUna (a generic type of quite a different
structure, to which I have thought it better to restore De Montfort's name Tinoporus), and
with Orbitoides (whose affinities with Cyclocli/pem and Kumiiiulilcs are of the most intimate
character), being then first created.

* It is due to Prof. Ehrenberg to state tliat he liad long before recognised this relationship
(xxxix) ; but by ranking Orbicidbia as well as Orbitolites among Bnjozoa, and by representing the
superficial cells in both types as occupied by eiglit-aruied polypes furnished with moveable opercula,
he so completely departed from the truth of nature, that it is not surprising that what was really correct
in his doctrines received little attention.

14

106 FAMILY MILIOLIDA.

155. External Characters. — The calcareous disks of Orbitolites (Plate IX, figs. 1, 7) vary
in diameter from about l-30th of an inch to ^-lOths of an inch ; whether large or small,
the}' are almost invariably circular or nearly so ; they are usually flat or slightly biconcave,
any difference in thickness being generally in favour of the marginal portion ; and if, as
sometimes happens, there is a slight central prominence (fig. 7, a), this consists only of that
first-formed portion of the shell which I shall describe as the " primitive disk" (^ 157), and
does not result (as in Orbiculina, ^ 135) from any overlaying of the original centre by subse-
quent growths of shell. Around this " primitive disk" we see an indeterminate number of con-
centric zones marked out by farrows of the surface ; and each of these zones is subdivided by
transverse furrows into a uniform series of areolae, which correspond with " chamberlets"
within. In the smaller specimens (fig. 1) these areolae are usually somewhat ovate in form,
their long diameter lying transversely to the radius of the disk ; in the larger specimens
(fig. 7), on the other hand, they have usually a narrow, rectangular shape, and their length lies
in the direction of the radius of the disk. This difference will presently be shown to be related
to an important diversity in internal structure. In those disks which have their surface
divided into ovate areolae (fig. 1), the margin presents a series of convexities with inter-
vening furrowed depressions ; whilst in the thicker disks (fig. 7) these are less regular and
less strongly marked. Unless the surface of the disk has been partially or entirely removed
by abrasion (as is often the case with dead specimens collected by dredging), it presents no
openings whatever, and the only orifices by which the interior of the shelly disk normally
communicates with the exterior are the pores (figs. 1, 7,f,f) that are seen upon its margin. Of
these pores, in the thinnest specimens (fig. 1), we find but a single one, or in some instances
two, lying in each of the marginal hollows ; in disks somewhat thicker we find each furrow
to contain three or four such pores ; whilst in the largest and thickest disks (fig. 7) the
number of pores occasionally rises to ten or even twelve. Thus, on the one hand, by the form
of the superficial areolae, on the other, by the singleness or multiplicity of the rows of
marginal pores, there is marked out a distinction between two types of Orbitolite structure
which have been accounted specifically or even generically different, but which, as they
frequently coexist in the same individual, have no title to be so regarded. It will be conve-
nient, however, to describe them separately, in the first instance, as the Simple and the
Complex types ; and to consider their mutual relationship subsequently. In both these types
the aspect of the shell much resembles that of Orhiculina, but has usually less of the opaque
whiteness by which it is characterised in that genus ; and sometimes, as in Orhiculina, the
surface is minutely punctated, giving a semblance of perforations, which, however, have no
real existence. In very thin specimens the calcareous laminae which form the two surfaces of
the disk are so translucent that, when such specimens are mounted in Canada balsam, the
chambers they enclose can be clearly made out. Moreover, even in larger specimens which
have been collected alive, and which consequently contain the animal body in a desiccated
state, the translucency of the shell allows the crimson hue of the sarcode to be seen through
it, so that the whole disk seems to be tinged by this, although the proper substance of the
shell, when examined by transmitted light under a sufficient magnifying power, is found to
present the brownish-yellow hue characteristic of the Milioline type.

GENUS ORBITOLITES. 107

156. Simple Type : External Characters. — In sands and dredgings brought from the seas
of any of the warmer regions of the globe, and especially in those from the Philippine shores,
we almost constantly meet with an abundance of minute Orbitolite-disks, whose diameter is
ordinarily about '05 of an inch, and which usually contain from ten to fifteen concentric zones.
These constitute the OrhiloKtes marginalis of Lamarck (lx), the Sorites orbicuhs oi Ehren-
berg (xxxix). Although these disks are typically plane or nearly so (there being usually
no great difference between the thickness of their central and that of their peripheral region),
yet it not unfrequently happens that the successive zones gradually increase in thickness
from within outwards (as is shown in Plate IX, fig. 2), so that the disk becomes somewhat
biconcave. Sometimes, again, without any alteration in the thickness of the several parts,
the disk comes to assume, by the depression of its central portion, the shape of a plate, or
that of a watch-glass, or (by the more complete upturning of its edges) that of a saucer.
In any case in which either surface of the marginal zone is more exposed by its projection
than those of the zones which it encloses, there will be a special liability to a laying-open of
its chamberlets if the disk should be subjected to attrition ; and I doubt not that in this
mode have been produced the supposed large pores of the fossil 0. macropora, the figure of
which given by Goldfuss (' Petrefacta,' pi. xii, fig. 8) corresponds exactly with recent specimens
I have frequently encountered, presenting a row of large ovate apertures along the surface
of the outermost zone. The true pores (which have been very commonly overlooked) are
situated in the depressions between the marginal convexities (Plate IX, fig. 1,/,/) ; in each
of these depressions there is but a single pore, and this is almost always of a regularly
circular form, and is surrounded by a prominent annulus of shell.

157. Internal Structure.— When the interior of an Orbitolitcs of simple type is laid open
by a section that passes in a direction parallel to one of its surfaces (which in the case of
these discoidal forms will be most conveniently termed a horizontal section), as shown in
Fig. XXIV, the central portion is seen to be occupied by a large cavity, that is somewhat
irregularly divided by a sinuous partition ; notwithstanding some irregularity, this partition
always marks out a " primordial chamber," a, of a somewhat pyriform shape, from the
" circumambient chamber" b, b, which passes round it ; in this partition there is an aper-
ture, d, which establishes a communication between the narrow prolongation of the " pri-
mordial" or " central" chamber and the large " circumambient chamber." (See also Plate IX,
fig. 1.) The meaning of this arrangement will at once be made apparent by reference to
the disposition of the " primordial" and " circumambient" segments of sarcode, which occupy
the cavity of what may be conveniently termed the " primitive disk" (^ 161). In a vertical
section passing through the centre of this disk, such as that seen in Plate IX, fig. 2, it seems
to present three chambers ; but this is simply due to the fact that such a section will traverse
the circumambient chamber twice, that is, will cut it through on both sides {b, b) of the
central chamber a. Some sections present only two such chambers ; in this case the plane
of division seems to have traversed the "primitive disk" just where the neck of the
primordial chamber touches its margin, so that the circumambient chamber is only on
one side of it. If, on the other hand, the plane of division should happen not to pass
through the primordial chamber at all, so as to traverse the circumambient chamber
alone, a single broad cavity will present itself in the vertical section, as shown in fig. 8, b.

'108

FAMILY MILIOLIDA.

Frequently, however, it happens that the circumambient chamber is partially subdivided on
one side by an interposed partition (Fig. XXIV) ; and then a vertical section will show /o?er
chambers, the central chamber having the undivided part (i) of the circumambient chamber
on one side of it, and the divided part {li, b') on the other. Each zone, as seen either by
transmitting light through the thinnest and most translucent specimens after mounting them in
Canada balsam, or by making horizontal section of thicker specimens, consists of a circular set
of small ovate cJiamherkfs [c, c, Fig. XXIV, and Plate IX, fig. 1), excavated, as it were, in the

Fig. XXIV.

Diagrammalic ix-prcseutation of the anterior of an Orbiloliies of simple type : — a, primordial chamber ; b, h, circumambient
chamber ; b', portion of the same partially separated by an incomplete partition ; c, c, c, chamberlets of the concentric
annuli ; d, passage from the primordial to the circumambient chamber ; e, e, e, passages from the cireumambieut cham-
ber to the chamberlets of the first annulus; /,/,/, passages from the gallery of the last anuuhis, opening at the
marjin of the disk.

shelly substance of the disk, and communicating with each other laterally by annular passages
which unite them together into a continuous gallery. The zone which immediately surrounds
the " primitive disk " is connected with it by radial passages (Fig. XXI, e, e), which extend
from the outer margin of the large circumambient chamber to the several chamberlets of
which that zone is composed ; and each zone communicates with the one on its exterior by
similar radial passages (Plate IX, fig. 6, e, <•), which usually extend, however, not from the
chamberlets of the inner zone to those of the outer, but from the annular passage {li, h) of
the inner zone to the chamberlets of the outer ; and thus it comes to pass that the cham-
berlets of each zone usually alternate with those of the zones that are internal and external
to it. — A vertical section of the disk, such as is shown in Plate IX, fig. 2, exhibits the same
arrangement under a diflferent aspect. The chamberlets c, c, c of the concentric zones are

GENUS ORBITOLITES. 109

seen to be much higher than they are broad, so that they present a somewhat coUimnar
form ; the proportion of their height to their breadth, however, may vary greatly in different
parts of the same disk, the former often increasing from the centre towards the periphery,
whilst the latter remains constant, or nearly so; and the columns, instead of being straight,
are generally more or less curved, and are sometimes bent in the middle at an obtuse angle.
The gradation which presents itself from one of these forms to the other, and their coexist-
ence even in the same specimens, clearly prove that no value can be attached to the form
and proportions of the chamberlets, thus seen in a vertical section, as furnishing specific
characters. In every perfect specimen the columnar chamberlets are seen to be closed at
their two extremities by a thin wall of shell ; and this is sometimes flat, sometimes more or
less convex.

158. In this manner any number of concentric zones may be formed, which are exact
repetitions of each other, except that the number of chamberlets in the outer zones is greater
than that of which the inner zones are composed. It does not increase, however, in the
regular ratio of the respective diameters of the zones ; for the chamberlets of the outer
zones, being usually both larger and more widely separated from each other than are those of
the inner, are less numerous in proportion ; thus, in a specimen before me, there are twenty-
eight in the innermost row and only forty-nine in the outermost, though the latter is more
than twice the diameter of the former. The augmentation in number is accomplished by
the occasional interpolaiion of an additional chamberlet, communicating directly with the
one immediately interior to it, between the two chamberlets which are connected with the
annular passage on either side of the latter, as is shown in Plate IX, fig. 6, c' , c". The
chamberlets of the last-formed zone communicate with the exterior by the same kind of
radial passages as in other instances communicate with the next zone ; and the external
orifices of these form the pores which present themselves at the margin of the disk (Plate IX,
figs. 1, 2,/,/). Thus it is seen, on the one hand, how it happens that these pores are
intermediate between the chamberlets, instead of opening directly into them ; and on the
other, how each pore leads, by the divarication of its passage, into two chamberlets, one on
either side of it. When a new zone is formed, each pore opens into one of its chamberlets ;
and this zone, in its turn, communicates with the exterior through a new set of pores at its
own margin. When the section passes through the prominent annulus of shell which
surrounds each pore, this will be indicated by a little " beak" on either side of the entrance
to the passage ; such " beaks" (which are, of course, repeated through the entire disk)
are shown in their ordinary aspect in Plate IX, fig. 6, /, /), but they are frequently
more prominent. In all cases in which the growth of the disk takes place with
normal regularity, a complete circular zone is added at once. Exceptions to this regu-
larity are rare, and they can be generally traced with probability to some accidental
interruption.

1 59. It is a fact of much importance, in the due appreciation of the relations of
Orhilolifes to other types of Foraminifera, that the calcareous partition which separates each
chamberlet of any one zone from the adjacent chamberlets on either side is not double, but
siyic/le. And this is in great part the case, even with regard to the partitions which separate

110 FAMILY MILIOLIDA.

the chamberlets of successive zones, the inner or central boundary of one being chiefly
formed by the peripheral wall of the other. It is not easy, even in thin sections, to distin-
guish the boundary between the walls of one zone and those of another, so absolutely
continuous do they appear to be. But it not unfrequently happens that, in fracturw(i these
disks, their component zones come apart from each other along their natural lines of junc-
tion, so as to disclose the real inner margin of the outer zone (Plate IX, fig. 1, g, (/), which is
then found to present a set of wide fissures, through which we look at once into its cham-
berlets, thus proving their incomplete enclosure by proper walls on that side.

1 60. There cannot be any reasonable doubt that the number of concentric zones which
any disk may present is entirely determined by its stage of growth, and that it aftbrds no
basis whatever for specific distinction. Just as in the case of the concentric layers of wood
in the stem of an exogenous tree, a minute " primitive disk," surrounded only by a single
annulus of chamberlets, may come in time to be the centre of a large disk consisting of
many scores of concentric zones. Although, as already stated (^ 156), most of the Orbi-
tolites formed upon this simple type are of comparatively small size, yet there does not seem
to be any definite limit to the multiplication of zones ; for I possess specimens attaining '25
of an inch in diameter, and consisting of about fifty zones (much larger, therefore, than the
younger disks of the complex type), in which there is no appearance of any departure from
the original mode of growth.

161. Structure of the Animal.— The; entire animal body, obtained by the decalcification of
the shells of specimens that have been taken alive and preserved in spirit (Plate IV, fig. 14),
is composed, of a numerous assemblage of minute segments," arranged at tolerably regular
intervals in concentric zones, around what it may be convenient to term the " primitive
mass." This primitive mass consists of a pear-shaped " primordial segment" (Plate IV,
figs. 1 6 — 20, a) occupying the central or primordial chamber, from the small extremity of
which a peduncular process [d) extends, that dilates again into the still larger segment h, b,
which, from its almost completely surrounding the former, may be conveniently designated
the " circumambient segment." Thus, the " primitive mass" very closely resembles what the
body of a young Miliola would be, if the segment first budded-oft" from the primordial
segment were prolonged, so as completely to surround it (1 49, Plate IV, fig. 4, b). From
the outer margin of this circumambient segment there radiate a number of slender pedicles
(c), which presently enlarge into as many columnar segments, having a circular or oval base,
and these are united to each other laterally by a connecting band or " stolon" {h, h), which
passes entirely round the " circumambient segment" and forms a complete annulus. It is
usually from the portions of this "stolon" which intervene between the segments of each
annulus of sarcode, that the radiating pedicles (fig. 23, e, c, e) are given off, which go to
originate the next zone ; but sometimes a pedicle is given oft' from one of the segments (as
shown at e',e'), which goes to form a segment (c", c") in the next zone, that is interpolated
between two which have originated from the intervening annular stolon ; and it is in this
manner that the numJjer of segments in successive zones receives an increase, the size of those
segments not undergoing any considerable augmentation. Each successive zone exhibits
precisely the same structure ; and it is obvious that the radiating pedicles of the outermost

GENUS ORBITOLITES. Ill

zone will issue from the marginal pores, and will give origin to the pseudopodia by whose
action the life of the entire composite organism must be sustained. The analogy of other
Rhizopods would lead us to suppose that it is by the introduction of alimentary particles
(chiefly minute forms of vegetation), through their means, into the mass of sarcode of which
they are extensions, that the fleshy body pervading the entire disk is nourished. For
although there is nothing like a digestive cavity in any part of it, or an alimentary tube
passing from one portion to another, still less any vascular communication between the
segments, yet as the sarcode forms one soft homogeneous mass everywhere continuous, the
body as a whole will receive the benefit of any incorporation of new matter with its substance,
in whatever situation this may be made. That organic particles small enough to pass
through the marginal pores are thus introduced into the chambers of the disk, is proved by
the curious fact that the residuum left after the decalcification of large and therefore aged
disks, whose animal contents have not been preserved, consists almost entirely of an
assemblage of remains of minute Diatomacca, Desmidiece, &c., which have obviously been
retained in the interior of their cavities after the assimilation of the nutriment they were
competent to afford. The sarcode-body of the animal, growing at the expense of the nutri-
ment thus appropriated, will gradually, it is probable, project itself through the marginal
orifices, not merely in filamentous pseudopodia, but in quantity sufficient to form a new zone;
and it is easy to understand, from the analogy of other Foraminifera, that such extensions will
coalesce with each other laterally, so as to form a complete annuhis around the entire
periphery of the dislc. This, at any rate, must be the case when a new zone is to be added to
the shell ; and it would seem as if this annulus then undergoes a thickening into segments by
the accumulation of sarcode at the points at which it receives the radiating pedicles from the
last zone of the sarcode-body included within the shell, whilst it becomes narrowed in the
intervening portions, which form the connecting bands between the segments. It may be
presumed to be by a calcareous exudation from the surface of this beaded ring of sarcode,
that the formation of the new shelly zone is accomplished ; and if the calcifying process com-
mence on the segments, and extend from these along the surface of their connecting stolons,
we can understand why the passages that are left for communication with the exterior should
arise from the intermediate divisions of the annular canal rather than from the segments
themselves. — Although the body of the animal is so far decolorized in the spirit-specimens
which alone have hitherto come under my observation as to present only a brownish hue,
yet as specimens that have been gathered fresh and have been then dried possess a reddish
aspect, which is due to the desiccated body they contain, it may be presumed that the
sarcode of the living Orbifolites has the same bright-red colour as that of Botalia and many
other Foraminifera.

162. I have not met with the least indication that the sarcode is contained within any
prosier membrane ; and the absence of any such indication, notwithstanding the various
manipulations to which I have subjected its segments, may be taken, I think, as strong
negative evidence that it has no more existence in this animal than it has in the species ot
Foraminifera whicii have been so well studied by M. Dujardin and Prof. Schultze. Nor is
there the slightest trace of distinct organs, either in the mass of sarcode which forms the
"primitive mass" or in that which constitutes each one of the surrounding segments; and

112 FAMILY MILIOLIDA.

he would, I tliink, be a mere speculator who should maintain the presence of a digestive
cavity in any of these parts, or the existence of an intestinal canal in the peduncular threads
which connect them together. The homogeneity of the component substance of the
"primitive mass," and of the entire assemblage of multiple segments, seems, indeed, to be
conclusively established by the following facts : — In all the spirit-specimens which I have
examined, the cavities of the outer zones are completely void, whilst those of the " primitive
disk" and of the inner zones are quite filled with their animal contents. This drawing
together of the soft body towards the centre is evidenced also in many of the larger specimens
which have been dried when collected in the living state, by the limitation of the red colour
that indicates tlie presence of the sarcode to the inner portion of the disk. In both cases it
may be presumed that the animal matter has shrunk together, in the former through the
corrugating action of the spirit, in the latter through desiccation. Now if the " polypidom"
of a Zoophyte or the " polyzoary" of a Polyzoon be similarly treated, there is no such
drawing together of the entire body, but each cell is found to contain the shrunk contents of
its own zooid ; and this difference seems to me to indicate a complete dissimilarity in the
characters of the two kinds of organisms. For it is obvious that the substance of the
peripheral segments of the Orbitolite-body can only be brought together towards the centre,
through being completely unattached to the walls of the cavities which it occupies, and
through having a form so alterable as to be capable of being drawn in threads through the
narrow connecting passages, and of then coalescing together again so perfectly that the masses
they form do not present the least trace of having been thus spun out. There is no known
kind of animal texture except sarcode that is susceptible of this kind of alteration ; and the
evidence of it which I have adduced seems to me extremely valuable, not only as establishing
the general nature of the animal body of Orbitolites, but also as fully justifying the assumption
that, in the living state, the sarcode is projected in pseudopodia through the marginal
apertures, and that alimentary particles are introduced by their instrumentality, as in other
Foraminifera.*

163. Complex Type: External Characters. — From the simplest it will be convenient
to pass at once to the most complex type of structure presented by Orbitolites, the existence
of which is marked externally (as already noticed, ^ 155) by a multiplication of the ranges of
marginal pores. I have met with this form in specimens obtained by dredging from the
coast of Australia and from various parts of the Polynesian Archipelago, from the neighbour-
hood of the Philippine Islands, from the Red Sea, and from the J^gean ; and as the sands of
all these localities present the simpler type in great abundance, I am disposed to believe that
the former is really not the less widely diffused than the latter, and would be discovered
wherever it abounds, if properly searched for. The largest specimen in my possession,
measuring 7-lOths of an inch in diameter, is from the coast of Australia, where these
Orbitolites are so abundant at certain spots (as I learn from Mr. Jukes) that their entire

* I tliiuk it desirable to repeat what I have already (xiii) stated upon this point, since the per-
sistence of Prof. Ehrenberg in his affirmation of the Bryozoic nature of these organisms might induce
those who rely on his authority to accept his figure of their animal (xxxis) as the representation of a
fact, instead of being merely the expression of tlieir author's idea.

GENUS ORBITOLITES. 113

disks and fragments, with fragments of Corallines (chiefly, I believe, the Corallina palmata of
Ellis), constitute the great mass of the dredgings. Among the Australian specimens several
attain a diameter of "-^S inch, and a considerable proportion as much as '30 of an inch.
Hence the Orbitolites of this type are among the largest forms of existing Foraminifera, being
only surpassed, as far as I am aware, by the Cyclochjpeus hereafter to be described. Of two
specimens in my possession from the Fiji Islands, one measures '63 inch, and the other -53
inch in diameter ; but the average of the Polynesian specimens seems to be considerably lower
than that of the Australian, as their diameter seldom exceeds -25 of an inch, and is usually
not more than 10 or -12.

1 64. The disks formed on this plan, like the preceding, may be considered as typically
circular, although they are seldom or never exactly so in reality. They may be considered,
too, as typically flat, with a slight concavity in the central part, from which, however, the
primitive disk often projects ; but, as will hereafter appear, there is no constant relation either
between the thickness and the diameter of different specimens, or between the thickness of
different parts of the same specimen and the distance of these parts from its centre. The
only remarkable departure from the ordinary form which I have met with, presents itself in
certain Orbitolites from the Fiji Islands, of which several specimens in the Museum of the
Royal College of Surgeons, and two in my own possession, exhibit a curious plication towards
their margins ; the degree of this departure varies so much, however, in different individual?
(the plication being almost obsolete in some), that it cannot be admitted to mark a specific
diversity. These same specimens, moreover, also exhibit another curious abnormality ■
namely, the projection of the upper and lower edges of the margin, so that a groove is left
between them, the projecting laminae being thin and fohaceous, and their chamberlets very
irregularly arranged. This peculiarity, again, being far from uniform in its degree, and being
altogether wanting in specimens which in other respects precisely resemble those with plicated
and foliated margins, must be considered merely in the light of an accidental variety ; but I
cannot suggest any explanation of its occurrence, or of its limitation (so far as I am aware) to
this particular locality.

165. The surface of the disk (Plate IX, fig. 7)* is marked out, as in the simpler type, by
concentric zones, the number of which bears a general (though not a constant) ratio to its
diameter; these zones are traversed by radiating lines, which mark out areolae that are
usually somewhat rectangular in shape and sometimes approach a square, but are more com-
monly nearly twice as long in the line of the radius of the disk as they are in the transverse
direction, their long sides being nearly parallel to each other. We shall hereafter see, however,
that the form of these areolae is very subject to variation, and that it may be very dissimilar'

* In order to avoid a multiplication of figures, I have thought it preferable to combine in three
ideal representations (Plate IX, figs. 7, 8, 9,) the details I have made out from a great number of
preparations which are faithfully represented in separate figures accompanying the original Memoir in
the Arcliives of the Royal Society ; these last of course furnish the real authority for every point in the
description, the ideal figures, however, serving to display the relation of different parts to each other
in a manner that no single preparation would possibly admit.

15

114 FAMILY MILIOLIDA.

even in different zones of the same disk (^t 173, 178). The pores /,/ at the margin of the
disk are disposed, as in the simpler type, between the projections formed by the convexities of
the chamberlets ; but they are less regularly circular than in the simple type, and the sur-
rounding annuli of shell is less distinct. The number of pores in each vertical row
is by no means constant, even in different parts of the margin of the same annulus; and their
disposition is far from regular (fig. 10), as they seldom form rows that seem exactly con-
tinuous with each other horizontally, while the vertical rows are often interrupted, the two
adjacent rows then usually inclining towards each other.

166. Internal Structure. — The disks of this complex type are not distinguished from
those of the simple type already described, by any difference in the structure of the
" primitive disk ; " and there is frequently nothing specially characteristic in the structure of
the zones that immediately surround it. Each of the peripheral zones, however, consists of
two superficial layers, and of an intermediate stratum (Plate IX, figs. 7, 8, 9) ; these will now
be described seriatim. The superficial layers are formed of the (usually) oblong chamberlets,
whose contour is indicated by the surface-markings ; when they are laid open horizontally,
by rubbing away the thin shell which covers them in (fig. 7, i, i, i), it is seen that the
floor of each chamberlet has an aperture at either end ; but no communication can be
traced, either through the side-walls between the contiguous chamberlets of the same zone,
or through the end-walls, between the chamberlets of successive zones. Moreover, there is
no such alternating arrangement of the chamberlets of successive zones, as we have seen to
prevail in the simpler type (^ 157) ; and they altogether seem to be quite independent one
of another. When this superficial layer is examined in a vertical section having a radial
direction (Plate IX, fig. 8), it is seen that the floors of its chamberlets are formed by the
expanded summits (/, /,) of the irregular septa which separate from each other the successive
zones of columnar chamberlets of the intermediate stratum {r, c, c', c,) ; and that the
apertures at the two ends of the floor are the entrances to passages (w, ;«'), which lead
obliquely downwards (the passages on either side of the partition between two successive
chamberlets of the superficial layer always inclining towards each other) towards these
cavities. It is observable, moreover, that just at the point at which the contiguous passages
meet each other, there is always a round aperture (//, //) in the partition which divides the
contiguous chamberlets of each zone; and when, in a horizontal section, the superficial
chamberlets have been entirely ground away, so as to lay open the most superficial part of
the intermediate stratum, this part is found to be traversed in each zone by a continuous
circular gallery (Plate IX, figs. 7, 9, /i, //,//.,) with large rounded openings that lead into the
columnar chamberlets beneath. The meaning of this arrangement becomes obvious, when
We examine the disposition of the animal substance which occupies these cavities ; for we
find, as might have been anticipated, tliat the superficial cells are filled with segments of
sarcode of corresponding shape (Plate IV, figs. 24, 25, a, a'); and that whilst these have
no direct connexion with one another, each of them is connected by means of fleshy
peduncles with the annular stolons d, b' that run along its extremities ; whilst from the under
side of these annular stolons (fig. 25) descend the thick columns of sarcode {ce, c'c), which
occupy the columnar cells of the intermediate stratimi. The absence of any essential
dependence of the segments of the superficial and of those of the intermediate strata upon

GENUS ORBITOLITES. 115

each other, seems indicated by the fact that there is no constant numerical relation between
them, — a circumstance which extremely perplexed me, until I had ascertained, by exami-
nation of the animal, that the passages proceeding from the former (Plate IX, fig. 8, in, ?«')
debouch, not (as I had at first supposed) into the columnar chamberlets c ,c', but into the
annular canals, //, U , which serve to bring the superficial and columnar segments of each
zone into mutual communication.

167. As the description now given of the superficial layer applies equally to both
surfaces, we may now proceed to the intermediate stratum. When this is laid open by a
horizontal section (Plate IX, figs. 7, 9), it is seen to consist of a series of concentric zones,
the chamberlets of which alternate with each other, like those of the Simple type (^ 157).
The chamberlets are usually cylindrical (or nearly so) in form ; but often differ considerably
in size in different parts of the same disk, and sometimes even in different parts of the same
zone. It may be often observed that the cylindrical cavities do not always pass from end
to end in a straight line (Plate IX, fig. 11); nor do they always maintain a complete isolation
from each other, an inosculation of two columns (which is indicated in vertical sections
like that represented in Plate IX, fig. 8, by irregularly disposed apertures) not being unfre-
quent, while more rarely there is a fusion of two columns into one. All these features of
structure presented by the shell, are beautifully displayed by the animal (Plate IV, fig. 25) ;
the columns of sarcode c c, dc exhibiting the generally cylindrical form, the not unfrequent
inosculation, and the occasional fusion, which we have seen to exist in the cavities which
they occupy. At their upper and lower extremities, they unite with the annular stolons
JjJj , hU , which pass continuously round, in each zone, between the intermediate and the
superficial layers.

168. Save in the case of such accidental inosculations as those just noticed, no other
lateral communication seems to exist between the contiguous chamberlets of the same zone,
than that which is established by the annular stolons just mentioned. The chamberlets of
the successive zones communicate with each other, however, as in the Simple type previously
described (^ 157), but with a curious modification; for whereas a horizontal section of the
latter shows that each chamberlet communicates with the two chamberlets alternating with
it in the interior zone (Plate IX, fig. 6), a hke section of the Complex type seems to show
that such a connexion exists with only one chamberlet of the interior zone, by a passage
running obliquely from one to the other, and extending continuously through several succes-
sive zones (Plate IX, figs. 7, 9, e, e), the very same section exhibiting opposite obliquities in
contiguous parts. The study of vertical sections, however, made tangentially instead of
radially, so as to cross these connecting passages, shows the explanation of tbis apparent
anomaly to be simply as follows. Each cylindrical chamberlet really communicates with
the two alternating chamberlets in the next interior zone, but by two distinct passages,
instead of by the divarication of one ; these inter-zonular passages are not upon the same
plane, but those of different planes are directed alternately towards one side and the other ;
and thus, as the disks are seldom perfectly fiat, the section which traverses, at one part of
the disk, the set of passages running in one direction, will traverse the other set of passages,
where, by the flexure of the disk, the plane of section is slightly altered in regard to it. So

116 FAMILY MILIOLIDA.

the marginal pores of any one vertical row, even when in a line with each other, open alter-
nately into the chamberlets on the rifjld and on the left of that row ; these pores being
nothing else than the orifices of the oblique inter-zonular passages, which, when another
annulus is added, will lead into its chamberlets. The import of this arrangement is at once
made evident by an examination of the segments of the animal body that occupy the cylindrical
chamberlets ; for, as is shown in Plate IV, fig. 25, each column of sarcode in one zone (c c)
communicates with the two columns alternating with it in the next zone {c'c) by two rows
of peduncles ; and the peduncles which pass from each pair of contiguous columns to the
single column of the next zone, incline towards one another, so as to enter it nearly in the
same vertical line, though in different horizontal planes.

] 69. That which has been already stated in regard to the partial deficiency of the inner
wall in each of the concentric zones of the Simple type (^ 159), holds good also in regard
to the septa which divide the successive zones of the "intermediate stratum" in this more
Complex type ; for the walls of the cylindrical chamberlets close-in around them very imper-
fectly on their inner or central side, leaving large irregular vertical fissilres (Plate IX, fig. 11)
which are applied to the vertical rows of orifices (fig. 10) on the outer margin of the included
zone.

170. The thickness of this "intermediate stratum," and the number of superposed
segments (indicated by that of the inter-zonular peduncles) of which each column of sarcode
consists, are found to vary considerably in different parts of the same disk ; being usually
least near its centre, and gradually augmenting in successive zones as their distance from
this increases (Plate IX, fig. 8) ; or ceasing to augment at a certain point, so that the outer
part of the disk is flat ; or even diminishing again, so that the disk thins away towards its
margin. It is specially worthy of note that whatever differences of this kind may exist, they
are entirely due to the variable length of the columns of the intermediate stratum ; the depth
of the chamberlets of the si'jjerficial layers being nearly constant, and no vertical multiplica-
tion of these ever taking place.

171. The addition of new zones usually takes place Avith the same regularity in the
Complex as in the Simple type of structure ; but departures from this regularity, occasioned
by a want of completeness of particular zones, are more frequent ; and this is perhaps to be
accounted for by the larger size of the disk, which will tend to produce a less intimate
dependence of each part of the animal body upon every other, and will thus favour the
partial action of any cause {e.g. an excess of nutrient materials) which promotes a more
rapid growth on one side than on the other. And this view is most remarkably borne out
by the fact, that in the genus Cychchjpeus, which, though normally growing upon the cyclical
plan, possesses a much greater degree of segmental independence, such irregularities occur
far more frequently ; so that, in fact, it is rare in that type to meet with a disk whose increase
has taken place with uniformity throughout.

172. The foregoing description apphes in every particular to those specimens only,
which present the structure of the Complex type of Orbitolifes in its most regular and charac-

GENUS ORBITOLITES. 117

teristic development ; and the differences between this and the Simple type previously
described are such as at first sight to preclude the idea of their specific identity. But when
a large number of specimens are carefully examined and compared with each other, it
becomes obvious that not only may a vast amount of diversity present itself in the arrange-
ment of the chamberlets of the shell and of the segments of the animal,— so that one after
another of the characters which at first seem most clearly marked and therefore most
distinctive, may be shaded off" (so to speak) in such a manner as to establish a complete
transition between the two types, — but they frequently coexist in the very same disk. Such
a ^coexistence is exhibited in the vertical section represented in Plate IX, fig. 8, where we
see that the zones b — k, which immediately surround the "primitive disk," are formed in all
respects upon the Simple type ; between k and « we see an incipient diff'erentiation between
the " superficial " and the "intermediate" strata, the annular canal, however, still remain-
ing single ; but at n, the annular canal becomes double, and from this point to the margin
of the disk we see the " superficial " layers completely diff"erentiated from the " intermediate,"
and the former becoming more and more widely separated from each other by the increasing
thickness of the latter. Now as the Complex type of growth may show itself in the very
first annular zone, or may thus evolve itself out of the Simple at any distance from the
centre, and this either suddenly or gradually, it seems obvious that between these two types
no essential distinction can exist. If the growth of such a disk as that whose vertical
section is represented in fig. S, had been stopped at k, or even at n, it would have
undoubtedly been regarded as belonging to the Simple type ; and every disk formed upon
the Simple type must be considered as having the power to evolve itself upon the Complex
plan. It would not be right, however, to afiirm that the Simple disks are the young of the
Complex, since we find that the former may continue to increase without change, until
they far exceed in diameter and in number of zones the smaller disks which have early
assumed the latter type. Of the conditions which determine the original evolution of the
Simple or of the Complex type respectively, from "primitive disks " which appear to be in
all respects identical, or which determine the evolution of the latter from the former, we
know nothing whatever.

173. Even where the annular canals have been separated from each other, and a
distinct " intermediate stratum " has been formed between them, the superficial chamberlets
are not always clearly marked off" from its cylindrical cavities ; for instead of being separated
by floors formed by the expanded summits of the zonal septa (^ 166), they sometimes open
at once into the chamberlets of the intermediate layer, so as to be quite' continuous with
them ; and this continuity of the superficial with the intermediate chamberlets is sometimes
maintained throughout the disk, so that in no part of it are the former clearly marked off"
from the latter. This method of growth is so remarkably constant in the fossil Orbitolites
of the Eocene strata, whose intermediate layer is fully and very regularly developed, that it
might be considered to be specifically characteristic of them, did we not occasionally find it
to occur in certain zones of recent disks, which are elsewhere exactly conformable to what J
have described as the regular type. Where the superficial chamberlets are continuous with
those of the intermediate substance, they present the rounded or ovoidal shape, instead of
the elongated straight-sided figure which is their characteristic form ; and the former seems

118 FAMILY MILIOLIDA.

to give place to the latter, whenever the chamberlets of the superficial layers are perfectly
separated from those of the intermediate stratum, and are connected only with the annular
passages.

174. The "intermediate stratum," again, may be altogether wanting, notwithstanding
that the two superficial layers are separated from each other by a horizontal partition. In
this case, each layer may have its own annular canal, or there may be but a single canal,
which is then genei'ally very large ; and the chamberlets of the two layers have an alternating
arrangement as regards each other. Such an arrangement may present itself as one of the
modes of transition from the Simple to the Complex type, the cylindrical chamberlets
being disposed to subdivide transversely when they attain a considerable length, and the
annular canal to become double ; whilst in zones more distant from the centre, the two
layers are separated by the interposition of the intermediate stratum. Sometimes, however
the disk continues to increase and attains a considerable size on this duplex type, as we see
especially in the Orbitolites of the Red Sea ; and its edge then presents two rows of rounded
prominences with pores between them, those of the upper and lower rows alternating with
each other. It is on a dislc of this type that Prof. Ehrenberg has founded his genus
Amphisorus (xxxix), which I cannot regard as even specifically distinct from the ordinary
Orbitolik's. — There is sometimes a complete absence of regularity in the disposition of the
cylindrical chamberlets of the intermediate stratum, so that they present an assemblage of
indefinitely-shaped passages, communicating with each other in various directions. This
variety is chiefly interesting, as showing how little importance is to be attached to smaller
deviations of the same kind. Further, the septa dividing the contiguous chamberlets of the
same zone are occasionally deficient, so that the interior of the zone is a continuous circular
gallery, with only slight indications of the normal divisions ; thus corresponding exactly with
the peneropliform condition of Orhicidina (^ 143). In such a case, it is obvious that the
ring of sarcode must have been everywhere of nearly uniform thickness, showing no division
either into horizontal or into vertical segments; and it may not be thought improbable that
this is its first condition in every case, and that its segmental division is a subsequent process,
so that the shelly investment, if formed previously to the segmentation, will have the
character of incompleteness just described. I cannot lielp suspecting, that the peculiar
groove around the margin of the Fiji specimens formerly noticed (Ij 164), is referable to a
still greater incompleteness of the production of the calcareous investment around the newly-
formine zone.

'&

175. Reparation of Injuries. — Much light is thrown on the physiology of the Orbitolite
type of structure, by the examination of specimens — of which I have met with several —
whose conformation makes it evident that, after larger or smaller portions of the disk had
been broken away, a new growth has taken place along the fractured edge. Two examples
of this are shown in Plate IV, figs. 26 and 27. — In the first of these, it is obvious that so
large a portion of the disk has been broken away, as to leave only an irregular fragment,
including its centre and about an eighth of its margin. Here seven zones have been formed
since the injury ; and the chamberlets of these, whilst produced conformably to those of the
uninjured margin a, a, present the most marked want of conformity to those of the fractured

GENUS ORBITOLITES. 119

margin, which, nevertheless, they completely surround. A careful examination oi this
specimen, indeed, seems to me to leave little room for doubt, that the growth of the inner-
most or what I may call the rcparatirr zone of chamberlets took place, not from the broken
edge, but from the margin of the unbroken ; just as, to use a professional simile, an ulcerated
surface " skins-over" by an extension of the integument from its edges, not by the direct
formation of skin upon the granulation-surface itself All the six rows subsequently pro-
duced are conformable to each other and to the first or reparative row, from which they
have obviously extended themselves after the normal manner. It is observable, however,
that the breadth of these rows varies in different parts, being least where they invest the
projecting portions of the fractured edge, and greatest where they sink into its hollows.
And thus it comes to pass that the irregularities left in the shape of the disk, by the loss of
a large part of its substance, are gradually compensated, so as to restore it to a form much
more nearly corresponding to its typical symmetry. It is interesting to find evidence in
fossil specimens, that the same kind of reparation has taken place. Among the Orbitolites
which I have examined from the Calcaire grassier of Paris, is a disk of which a large part had
obviously been lost by fracture, but of which the original symmetry had been in great degree
restored by a similar outgrowth from the zones formed from the uninjured margin, along
the fractured edge. — In the specimen represented in fig. 27, in which but a very small frag-
ment appears to have served as the nucleus for a new disk, the tendency to the reproduction
of the typical form, by the compensative reparation just described, is still more curiously
marked. This specimen also presents the very unusual feature, that the new growth has
taken place from the inner margin of the original fragment {a, a), and not from its outer or
growing margin, as in the case previously noticed. Having carefully examined it in various
modes, I cannot entertain the slightest doubt that such has been the case ; for the chamber-
lets of the first new zone, as well as those of all the zones subsequently produced, are so
manifestly conformable to those of the thinner and older portion of the fragment, and are so
unconformable to those of the thicker and newer margin, that it seems obvious that the
sarcode must have extended itself from the former part, along the fractured edge on each
side, and have then enveloped the margin which had been left entire. This may have more
readily taken place in the present instance, because at the part a, a, the fracture seems to
have followed the course of one of the zones, instead of passing (as at the sides of this
fragment, and as in the instance previously cited) in such a direction as to cut the zones trans-
versely.— Again, I have met with several specimens, in which the central portion of the disk
having been broken-out, a growth of new zones seems to have taken place from without
inwards, so as to fill up the void space thus left ; the included portion being evidently as
unconformable to that which surrounds it as in the preceding case, and a void remaining
unfilled, the shape of one part of which clearly indicates that it occupies the site of the
original centre ; — so as to render the conclusion almost inevitable that the included portion,
and not the peripheral, must be the after-growth.

176. This series of abnormal phenomena, then, not only confirms the conclusion that
seemed fairly deducible from our previous examination of the normal mode of growth, with
regard to the independent endowments of the component segments of the sarcode-body of
Orbitolites, but also affords some additional information of much interest. For we see, in

120 FAMILY MILIOLIDA.

the first place, that there is no relation of necessary dependence between the several portions
of the disk ; since not only can the greater part of the peripheral portion be lost without
any diminution in the growing power of that which is left, but even a fragment of the peri-
pheral portion, altogether detached from the centre, can not only maintain its vitahty, but
become the centre of a new disk. Secondly, the growth of the sarcode and the addition of
new parts may take place not merely in the peripheral direction from the normal outer margin,
but also in the direction of the centre, provided that a free edge be exposed at the inner
margin of any zone. Thirdly, the reparative iiisus seems always to tend towards the pro-
duction of a disk whose shape shall approach the circular, whatever may be the form of the
fragment which serves as its foundation ; thus showing that, notwithstanding the repetition
and independence of the separate parts of these organisms, each cluster, whether large or
small, is an integer, having an archetypal symmetry to which it tends to conform, — strongly
reminding us of the phenomena of crystallization. And fourthly, the plan by which this
recurrence to the discoidal form is provided for, seems partly to consist in the limitation of
the new growth to the natural margins of the zones ; no such growth taking place from the
edge of a fracture which has crossed the zones transversely, although it may proceed from
the remains of a zone which has been broken off by a fracture that partly follows its course.

177. Varieties. — We have already seen that diversities both m \\\e diameter awA in the
thickness of the disk arise directly from the degree in which the animal substance (whereon
the skeleton is modelled) has extended itself either horizontally or vertically, so as to multiply
either the number of concentric rings, or tlie length of the columnar segments of which each
ring consists. This, however, is not the only source of variation in size ; for a most extra-
ordinary diversity presents itself in the dimensions of the individual components by whose
repetition the entire disk is made up. It is in the " primitive disk " that I find this diversity
most strongly marked, the central area of one specimen in my possession being about
twenty-eight times that of another, and every intermediate gradation being presented by other
specimens. There is not by any means the same amount of difference between the dimen-
sions of the ordinary segments which form the concentric annuli ; nevertheless, these also
exhibit marked diversities in size in different specimens (the largest chamberlets being usually
found to spring from the largest primordial chambers, and vice versa), and the individual
cells of the very same disk being occasionally found to differ no less widely amongst each
other. Similar differences present themselves in the vertical height of individual chamber-
lets ; as is of course best seen in the Simple type of Orbitulites, in which the augmentation
in the thickness of the disk is produced merely by the elongation of the columnar segments.
I possess a series of vertical sections of different individuals, in which the same gradual
transition is seen from the thinnest to the thickest, as I have just stated to exist in regard
to superficial area ; and which also proves that the relative thickness of the central and of
the peripheral portions is equally liable to variation. — It seems obvious, from the foregoing
considerations, that neither the absolute nor the relative dimensions of the individual parts
of these composite fabrics can, any more than the dimensions of the entire disks, be taken
as affording valid characters for the discriminatiop of species ; and that such a wide range
of variation exists among individuals, as would, if the extreme cases alone were known, seem
fully to justify their separation under distinct specific designations.

GENUS ORBITOLITES. 121

178. The appearances presented on minute observation by the surface-marUngs of Orhi-
tolifes, which indicate the form and arrangement of its contained chamberlets, are so far from
being uniform, that to any one whose eye had not become familiarised with their variety by
the examination of a considerable number of specimens, they would become sources of great
perplexity. We have already seen that the subdivisions of the annuli visible externally
present two very distinct forms, the rounded or oval (Plate IX, fig. 1), and the rectangular
(Plate IX, figs. 7, 9) ; the first of these being specially characteristic of that Simpler type of
structure in which there is only a single layer of cells, but not being confined to it ; whilst
the second is peculiar to the Complex type, in which there are two superficial layers distinct
from the intermediate stratum. Now the occasional co-existence of both these plans of struc-
ture in a single individual (t 172) sufficiently proves that the diversity of the surface
markings to which they respectively give rise, cannot be regarded as a basis for specific
distinction ; and when these extremes of diversity are kept in view, it must be felt to be
highly improbable that any modifications of either form should possess greater importance
That such modifications are mere individual varieties, is further evidenced by their gradational
character, and by the fact that two or more of them may present themselves in the same
disk. In describing them, I shall limit myself to an account of those more remarkable and
frequently-recurring varieties, which will serve, I think, as a key to any others that are
likely to be met with. — Although each surface, in either of the two principal types, ordi-
narily shows a division into concentric zones, which are again transversely subdivided so as
to mark the separation of the chaniberlets, yet sometimes the concentric zones are alone
visible, and no transverse subdivision is indicated, save by the alternation of hghts and
shadows proceeding from a like alternation of solid substance and of hollow spaces beneath.
This predominance of the concentric divisions, which gives a very distinctive aspect to the
disks that exhibit it, is usually most apparent in individuals whose vertical section exhibits
two planes of cells ; and it has seemed to me to depend on an unusual freedom between the
lateral communications, which I have noticed in certain individuals thus formed, so that the
animal portion of each zone might be described as an annulus of sarcode, merely constricted
at intervals. This peculiarly cyclical aspect of the surface may pass into either of the
principal types previously noticed ; the concentric zones sometimes breaking up (so to speak)
into bands of rounded chamberlets with slightly convex roofs ; whilst in other instances they
are subdivided by very definite transverse lines into cells of remarkable squareness, which
still retain the original flatness of their surfaces. — On the other hand, the appearance of
concentric division is sometimes almost entirely wanting ; the surface of the disk exhibiting
excentric circular markings, which resemble those of an engine-turned watch-case, and the
boundaries of the cells being formed by the intersection of these with each other. This
aspect, which seems due to an unusual freedom in the oblique communications between the
cells in each zone and those alternating with them in the contiguous zones on either side,
insensibly passes into the ordinary type ; and it is not uncommon to meet with disks, espe-
cially fossil, which exhibit in one part the engine-turned aspect, and in another that of
concentric zones transversely subdivided. Indeed I have sometimes found that the very
same disk might be made to present either of these aspects, according to the manner in
which the light is made to impinge upon it and is reflected from it. — Although the rounded
or oval form of the superficial divisions is specially characteristic of the Simple type of

16

122 FAMILY MILIOLIDA.

Orbitolites, yet it is by no means restricted to this ; being frequently met with in the thicker
disks of the more Complex type, and being almost constant in the fossil forms that abound
in the early Tertiaries. Its occurrence, however, may always (I believe) be considered as
indicating an incomplete separation between the superficial segments and the columnar seg-
ments of the intermediate stratum (f[ 1 73) ; so that the former present the shape of the latter,
in place of that which properly characterises them. The shape of the chamberlet is
sometimes marked out in unusual strength by the convexity of its roof or cover ; and this
feature is often so pronounced in the large fossil Orbitolites of the Paris basin, as to become
visible to the naked eye. A veiy marked diversity in its degree, however, as w^ell as in the
size of the cells, is often to be noticed in contiguous zones ; whence it is obvious that the
convexity is a mere accidental variation, and is a character of no value whatever as regards
the differentiation of species. The relation of the rounded to the square or rectangular
charnberlets is made evident by the occurrence of intermediate Unks of transition. — The
foregoing considerations seem to render it obvious, that diversities in the form of the super-
ficial chamberlets do not afford any ground whatever for the estabHshment of a corresponding
multiplicity of specific types, but that they must rank as individual variations to which there
is scarcely any definite limit.

179. Besides those regular markings of the surface which correspond to the division
of the interior into chamberlets, a peculiar aspect is frequently given to it by extraneous
calcareous deposits, which are sometimes irregular, but which occasionally present an
approach to radial symmetry. It is worthy of note that these deposits present themselves far
more frequently, and also in a far more characteristic manner, in the Orbitolites of the
Philippine Seas, than in those of the Australian or of any other provinces ; and this circum-
stance seems to render it probable that the outgrowth is directly due to the influence of
some external condition, probably an excess in the proportion of carbonate of lime in the
w'aters inhabited by these particular specimens.

180. Although the cyclical Mode of Growth, w-hen once established, is subsequently
maintained with great regularity, and although in what may be considered the typical form
it commences from the " primitive disk " itself, yet there are numerous instances in which
the typical regularity is more or less widely departed from, so that the early increase seems
to take place after an altogether different plan. The most marked antithesis to that regu-
larly concentric type of growth, in which a complete annulus of chamberlets immediately
surrounds the primitive disk (see Fig. XXIV, •[[ 157), is presented by those forms in which
the circumambient segment has only given origin to new segments at its extremity ; these
in their turn bud forth others, which extend and multiply themselves laterally as well as in
advance ; and thus a kind of spiral is produced, which opens out very rapidly, the lateral
portions of its mouth tending to grow round and embrace the primitive disk. An example
of this kind, in which as many as twenty-two zones (counting the primordial segment as the
first) succeed one another before the first complete annulus is formed, is shown in Plate IX,
fig. 5. Another example of the like abnormality, taken from a specimen in which the " primi-
tive disk" had a remarkably Milioline aspect, is shown in Plate IV, fig. 21. Now if these
two plans of growth — the one cj/clical from the beginning, the other cyclical only after having

GENUS ORBITOLITES. 123

been at first spiral — were constantly presented in well-marked contrast with each other,
there would be good ground for considering them, as Prof. Williamson has done (cviii),
to be characteristic of distinct specific types. But this idea cannot be sustained w'hen a
large number of individuals are examined and compared. For it then becomes apparent
that the number of cases in which the primitive disk is surrounded on all sides by the same
number of zones, indicating that the concentric mode of growth has prevailed from the
first, are very few ; but that in by far the larger proportion of specimens there is a slight
excentricity of the primitive disk, witli a larger number of zones on one side than on the
other, as in Plate IX, fig. 3 ; indicating that the first-formed zones have been incomplete
circles, owing to a restriction of the gemmation of the circumambient segment to one part of
its periphery. This is shown extremely well by decalcified specimens of the animal, scarcely
any two of which, in fact, precisely resemble one another as to the mode in which the first
zone originates in the circumambient. Thus in the specimen represented in Plate IV, fig. 14,
of which the primitive mass is represented on a larger scale in fig. 20, the circumambient
segment gives off only three peduncles, at the end most remote from its connexion with the
primordial segment ; and the first zone of segments is far from being entire, the cyclical type
not being completely attained until two or three successive additions have been made. In
fig. 1 9 ei^ht peduncles are seen to be given off from the circumambient segment, and from the
half-zone which they form an entire circle is next produced ; thus affording a remarkable con-
firmation to the idea I have already suggested (^ 1 75), as to the capacity of a portion of a zone
to give origin to a complete annulus, by the lateral extension of its bands of sarcode. In
fig. 18 the circumambient segment gives off eleven peduncles on one side, and there are
indications of iliree or four on the other. In fig. 17 the peduncles come forth from a still
larger proportion of the periphery of the primitive mass ; the zone which first surrounds it,
however, is still incomplete in some parts, though the succeeding zone forms an entire circle.
In fig. 15 we see peduncles coming off from various parts of the circumambient .segment, in
which (as in the specimens represented in figs. 16, 17, 18) there is a partial separation of
a secondary segment b' . Finally, in the specimen represented in fig. 1 6, which is almost the
exact counterpart of the disk represented in Plate IX, fig. 4, and diagrammatized in Fig. XXIV,
the peduncles come off from the entire circumference of the circumambient segment, and the
annular zones of segments are complete from the first. The greater the limitation of the
power of gemmation to one side of the nucleus, and the larger the number of incomplete zones,
the more will the early plan of growth approximate to the spiral type, such as is represented
in Plate IX, figs. 3, 5. — It is obvious that the existence of such intermediate gradations
breaks down that barrier between the extreme forms, which Prof. Williamson had proposed
to erect ; and shows that in this, as in many other particulars, differential characters which
at first sight appeared to be perfectly satisfactory, lose all their force when carefully traced
through a sufficiently extended series of specimens.

181. Monstrosities. — Besides those departures from the normal type of growth which
have been described as variations or irregularities, there are certain others of rarer occurrence,
which can only be regarded as " monstrosities by excess ;" consisting in the production of
one or more incomplete secondary disks by outgrowth from the first. Thus in one specimen
in my possession the secondary disk forms a half-circle B D, of about the same diameter with

B

124 FAMILY MILIOLIDA.

the primary a c, and is superposed vertically upon the latter, the plane of junction passing
i> through its centre. In other specimens the secondary disk is relatively

smaller, extending only from the centre to the margin of the primary, but

"^ s still meeting it nearly at right angles. — In another specimen I have met

with, it would seem impossible to say which is the primary and which the secondary disk ;

and it might be more correct to describe the entire structure as consisting of a single half-

'C disk A B and of two half-disks b c and b d, meeting each other at an acute
angle c b u, neither of them being in the same plane with the single half-
disk, but both of them meeting it at similarly obtuse angles A b c and a b D.
In another case there rises from the surface of the disk a triradiate crest, formed by three
vertical plates meeting one another at nearly equal angles, but all of them neai'ly perpen-
dicular to the plane on which they rest. It is a very remarkable feature in this specimen,
however, that the line in which the three vertical planes meet is traceable at its base to the
centre of the horizontal disk ; so that they all bear the same relation to the primitive disk as
does the single outgrowth in the instances previously cited. Hence we may attribute all
such monstrosities (of which I possess a remarkable collection) to an excess of productive
power in the sarcode of the primordial segment, which has put forth its first extension, not
merely in the horizontal, but also in the perpendicular direction ; the whole subsequent
development of these outgrowths taking place after the normal plan, from the foundation
thus laid. I have occasionally met with instances, however, in which a vertical plate rises
from the peripheral portion of the disk, at a distance from the primordial chamber. — It is
interesting to remark that the presence of such outgrowths as those now described is far
more frequent in certain localities than it is in others. Among some hundreds of specimens
which I have examined from the coast of Australia, I have only met with five or six ; among
those yielded abundantly by the sand of the shore at Suez, such monstrosities are far more
frequent, and the excess more pronounced ; but in a small collection which I have inspected
from the Mgean Sea, the monstrosities of this kind were so numerous, that I think I am
scarcely vsTong in asserting that one specimen out of every three or four presented some
excess.* Among the fossil Orbitolites of the Paris basin, the presence of a completely
semicircular vertical plate is not at all uncommon.

182. Essential Characters of Orbitolites, and its Relations to other Types. — If, now, we
seek to determine the essential characters of Orbitolites, we find them to lie in the presence
of a series of annuli of sareode (and of corresponding galleries in the shelly disk) arranged
concentrically round a "primitive disk," which resembles a young Miliola ; each zone in the
simpler type containing but a single annulus, so constricted at intervals as to form a series of
somewhat columnar segments, which occupy the chamberlets of the shelly disk and are con-
nected with each other by stolons of sarcode ; whilst in the more complex type each zone

* This is by no means a solitary case of tlie prevalence of monstrosities in particular localities.
The collection of Mr. Bean, of Scarborough, contains a number of curiously distorted specimens of
the common Planorbis marftnatus, which have all been collected in one brook. Their peculiarities are
by no means repetitions of each other ; and I am disposed, therefore, to regard tliera rather as
resulting from the influence of external conditions, than as accidental varieties hereditarily propagated.

GENUS ORBITOLITES. 125

contains two such annuli, including between them a portion of its series of columnar segments,
so as to constitute an intermediate stratum, distinct from the snpcrfcial portions. In either
case, the segments of successive zones freely communicate with each other by radiating
peduncles of sarcode (also leaving jorwwyes in the shelly disk), whose normal direction is such
as to connect each segment with the two segments that alternate with it in each of the
adjacent zones. — The extreme freedom with which all the cavities of the shell mutually
communicate is a very marked feature in the structure of this type, as in that of Ortjiculina,
Alveotina, and Fab id aria ; and shows that the several parts of their animal bodies are far
more closely connected into one whole, than they are in those Foraminifera with perforated
shells which they most resemble in general plan of conformation. — The addition of
new zones, each similar to the last, is a simple matter of rjrowlli ; but the passage from
the Simpler to the more Complex plan marks an advance in devetopment ; and this
advance essentially consists (here as elsewhere) in a progressive differentiation of parts.
When, with the vertical extension of the columnar segments, the annular canal subdivides
itself into two, the communications between the successive zones no longer come-off, as
before, from the annular canal, but from the intermediate portions of the columnar cells ;
and instead of the two diverging passages from each cell being in the same plane, they lie in
different planes, alternating with each other vertically. Up to this point, we observe little
else than a multiplication of parts vertically, as well as horizontally, and a separation of con-
nexions that were previously confluent. But in the highest stage of development we find a
marked alteration in plan ; for those portions of the columnar segments, which lie between
the two annular canals of each zone and the two surfaces of the disk, become completely
differentiated from the portions that occupy the intermediate stratum, so as to form a peculiar
set of superficial chamberlets ; and these are so equally connected with two zones, as to make
it impossible to say that they belong specially to either. — Now we have seen that development
may be checked, while r/rowtlL continues, at any period of its progress ; so that we find
Orbitolites growing to a considerable size upon the very simplest plan, others still larger
formed upon the duplex plan, the largest yet known (fossihzed in the Paris basin) developed
upon the multiple plan without separation of the superficial chamberlets, while the most
complete, in regard alike to mvdtiplication and to differentiation of parts, are only found
among the disks at present existing; audit is interesting to observe that some of these
present this highest grade of development, while as yet of comparatively minute size.
There is scarcely any other type of Animal structure, in which so wide a range of develop-
mental variation normally exists. The lower classes of the Vegetable Kingdom, however,
especially the group of Fungi, afford abundant examples of it.*

183. The relation of Orbitolites to Orbiculina is of the most intimate kind. As already
mentioned (•[[143), it would not be possible to distinguish with certainty a fragment of the peri-
pheral portion of the former from a corresponding fragment of the cychcal type of the latter ;
though it is curious to observe that, whilst the differentiation of the superficial from the inter-
mediate strata is most complete in the Orbiculince of the early Tertiaries, it is least complete
in the Orbitolites of the same epoch ; and conversely, whilst it is least complete in the Orbiculina

* For a more detailed examination of the reputed species of Orbitolites, see xiii, p. 224.

126 FAMILY MILIOLIDA.

of the present time, it is most complete in the Orbitolites of our Southern Ocean. These
two types are at once distinguishable from each other, however, by a comparison of the centres
of their respective disks ; for not merely does OrhicuUna invariably commence on the spiral
plan, but it invariably persists in this until the spire has made three or four turns, of which
each invests the preceding, so as to augment the thickness of the centre, and to cause this to
project as a rounded knob above the plane of the peripheral portion of the spire or disk. In
Orbitolites, on the other hand, the cyclical mode of growth seems characteristic of the type ;
for even when the early growth follows a spiral arrangement, this seems simply to result from
a defective power of gemmation in the " primitive mass " of sarcode, and the spire never
proceeds beyond a single turn, or encroaches on the surface of the primitive disk, but from
the iirst shows a tendency to pass into the cyclical form.

184. The relation of Orbitolites to Tinoporus (the Orbitolina of D'Orbigny), to Orbitoides,
and to Cycloclypeus, is one of mere similarity in mode of growth, and consequently of analogy
only ; their essential characters being such as to remove them most widely from it. For as
Orbitolites is the cyclical type of the Milioline series, so shall we see that Tinoporus stands in
the like relation to the Rotaline, and Cycloclypem to the Operculine, whilst Orbiloides seems
to be a connecting link between the two latter.

185. Geographical Distribution. — This type, like OrbicuHna, is pretty generally diffused
along the shores of the warmer seas ; but it is interesting to observe that it is most abundant
where Orbiculina is comparatively rare, and vice versa. Thus, it is more commonly met with
in the Australian and Polynesian seas than in the West Indian or Philippine, and is peculiarly
abundant in the Red Sea (the shell-sand of Suez yielding it in extraordinary copiousness),
though not there attaining any large size or high development, whilst it seems to die out in
the Mediterranean, the specimens gathered on its shores being all of stunted growth. Its
largest size and highest development at the present time are attained in the Polynesian seas,
especially on the sides of Coral-reefs, where the disks that have become detached from the
sea-weeds to which they are usually attached, often accumulate to an enormous extent.

186. Geological Distribution. — The early part of the Tertiary period appears to have
been unusually rich in Foraminifera of the largest size. The C'alcaire Grossier of the Paris
basin, and corresponding formations in the south of Europe, contain enormous numbers of
Orbitolites, which often attain a diameter of 8- 1 Oths of an inch ; and the Limestones of the north-
west of India, which in some parts are rich in Orbicidina and Qrbitoides, are elsewhere almost
entirely composed of an equally large variety of Orbitolites, which Mr. Carter (xix) has
described under the name of Cycloliua, supposing it (from the peculiarly cyclical aspect of its
surface, 1178) to belong to the genus so named by D'Orbigny, which seems, however, to
have been really founded on a varietal form of Tinoporus. The true Orbitolites first makes
its appearance in the rich Polyzoic deposits of the shallow-water Maestricht chalk ; and it
has probably continued to inhabit the ocean waters, from the time when it first accumulated
so as to form an important constituent of the Eocene Limestones, down to the present epoch.
Whenever the Coral islands at present submerged shall in their turn undergo elevation, a new
series of Orbitolite-limestones, now in progress of formation, will probably be brought to light.

GENUS DACTYLOPORA. 127

Genus XI — Dactylopora (Plate X).

187. History. — The most singular varieties of opinion have existed as to the true cha-
racter of the fossil organisms on which the genus Dactylopora was founded by Lamarck (lx).
They had been previously noticed by Bosc, and had been referred by him to the genus
Heteporitcs, belonging to the group then regarded as Zoophytes, but now ranked as Polyzoan
Mollusca ; and in this allocation he was followed by Laraouroux. In separating them gene-
rically from Betcpora, Lamarck still associated them in the same group of supposed Zoophytes ;
his genus was adopted by Blainville and Defrance (vii), who assigned the like place to it ;
and it was accepted by many subsequent palaeontologists, as Goldfuss, Michelin, and Bronn,
without any question as to its character. By Blainville and Defrance, moreover, another genus,
PoJyfrype, was erected upon a mere variety of the same type ; and this also has been accepted
as a zoophytic form nearly allied to the preceding. In 1852, however, Bactytopora was included
among the Foraminifera by ]M. D'Orbigny (lxxiv) ; who showed, notwithstanding, by the place
he assigned to it, a misapprehension of its real nature scarcely less complete than that under
which his predecessors had lain ; for he ranks it in his Order Monosfeyues, next to the unilo-
cular Ovulites, and says of it : — " C'est une Ovulite egalement percee des deux bouts, pourvue
des larges pores places par lignestransverses." How utterly erroneous is this description will
appear from the details to be presently given ; yet M. D'Orbigny's authority has given it currency
enough to cause it to be accepted by such intelligent palaeontologists as Pictetand Bronn, who,
in the latest editions of their respective systematic treatises, have transferred Dactylopora to the
place indicated by him, not without the expression of a doubt, however, on the part of the last-
named author (x, 'Uebersicht,' p. 25), whether its true place is not among the FistulidcB, in alliance
with Synapta and Ilolotlwria, — a suggestion that indicates a perversion of ideas on the subject,
for which it is not easy to account. The complex structure of the organism in question was
first described, and the interpretation of that structure on the basis of an extended comparison
with simpler forms was first given, by Messrs. Parker and Rupert Jones (lxxix) in so unob-
trusive a manner as scarcely to challenge the attention which their investigations deserve ; and
I gladly avail myself of the opportunity which the present publication affords to give a fuller
account, with the requisite illustrations, of this remarkable type, the elucidation of which
seems to me not unlikely to lead to a reconsideration of the place assigned to many other
organisms at present ranked among Zoophytes or Polyzoa. This account will be chiefly based
on the descriptions already given (loc. cit.) by those excellent observers ; but it will depart
from these upon several points, as to which the further investigations which we have jointly
prosecuted have led to a modification of their original conclusions. The illustrations in Plate X
are carefully drawn, by Mr. G. West, from the beautiful series of specimens with which they
have furnished me, and which they have kindly allowed me to treat in any manner that I
thought desirable for the elucidation of their structure.

188. External Characters and Internal Structure. — The t3'pe we have now to investigate
is one which, like the three preceding, exhibits itself under such a variety of modifications of
form, and so many dissimilar phases of development, that only by a careful and extended

128 FAMILY MILIOLIDA.

comparison can the mutual relations of these be discovered ; and it will be desirable, instead of
commencing with the complex organism on which the genus was originally established, to
examine in the first instance those simpler or more elementary forms which afford the clue to
the interpretation of its character. For each of the principal modifications I am about to
describe, I shall adopt the distinctive name assigned to it by Messrs. Parker and Rupert Jones ;
but these names are to be understood as used merely for the sake of convenient identification,
and not as intended to indicate a definite boundary between the forms the}^ respectively desig-
nate,— no such boundary having, in our opinion, a real existence.

189. In the East Indian and other tropical seas, generally adherent to the surface of
large, foliated, bivalve shells, such as Chama or Hippopus, but occasionally free in shell-sands,
the simple pupoid forms represented in Plate X, figs. 1 — 7, are not uncommon. Each of these
is composed of a linearly-arranged series of chambers entirely disconnected from each other ;
the external walls of these chambers and their dividing septa are very thick, and are
composed of porcellanous shell-substance exactly resembling that of the higher types of
Foraminifera with which we have been last engaged ; and their surface sometimes exhibits
minute pits, resembling those which we have seen to be common on the exterior of many of
the porcellanous series. Although the succession of these chambers is sometimes almost
rectilinear, it is generally more or less curved ; and the curvature is sometimes so great
that the series forms a half ring. Every chamber opens separately by a single large pore on
the middle of the concave side ; and this pore is surrounded, as in Pe/ieroplis, Orhitolites, &c.,
by a prominent annulus of shell, which is sometimes so thick and large as to form a nipple-
shaped protuberance. The number of chambers is extremely variable, and is obviously depen-
dent upon successional growth. Although specimens are occasionally met with in which the
surface is smooth or nearly so, it much more commonly presents a strongly marked alternation
of ridges and furrows (figs. 3, 7), the former corresponding with the interseptal spaces, and the
latter with the septa ; there are instances, however, in which the interseptal spaces are depressed,
as in fig. 8, instead of being elevated. It now and then happens that the chambers are piled one
on the other, so as to form part of a double series (fig. 6). The length of any series will, of
course, depend upon the number of chambers which it contains ; the breadth of these bodies
usually varies between '007 and 012 incli. Tlie simple structure of this organism is diagram-
matically represented, as shown by horizontal and vertical sections, in Fig. XXV. Its mode of

growth would be not a little perplexing, if we did not bear
Fig. XXV. in mind what has been already stated as to the extension of

the sarcode-bod}' over the exterior of the shells of Forami-
nifera (^ 33), and the formation of new envelopes by portions
of that body protruded from the aperture (^ 31). It has

been shown to be probable, in the case both of Orhitolites
Diagrammatic Sections of Dactylopora -, ^i t •• •/• ii-ii\i

m,«:-A, horizontal; e, vertical. ^nd AheoJina, that (at certam tmies, if not habitually) the

pseudopodial extensions from the separate pores coalesce with
each other on the exterior of the aperture ; and there is no more difficulty in understanding
how, from such a coalesced stolon of sarcode, a new chamber may be added to either extre-
mity of the linear series, or may be built (so to speak) as part of a new storey above it, than
there is in accounting for the formation of such a chamber in direct continuity with the aper-

GENUS DACTYLOPORA.

129

ture of the preceding. We shall presently see in the more complex forms of Bactylopora a
very marked indication that such a coalescence really takes place ; the apertures of the
principal chambers being received into a gallery that obviously lodged a stolon by which the
isolated segments are brought into mutual connection. — The type now described, which
presents itself in some of the French Tertiaries under a form (see figs. 4, 8) precisely identical
with the recent, is distinguished as D. eruca.

Fig. XXVI.

190. It is obvious that the continued growth of such bodies along a circular curve would
ultimately complete them into rings ; but it does not appear that such an elongation of the
pupoid form of Bactylopora ever takes place, as would be required to complete the large
circle which their moderate curvature would generate. In the " calcaire grossier " of
Grignon and other Tertiary deposits, however, the pupoid forms are accompanied by complete
annular disks (figs. 10 — 14), having a structure in every essential respect similar to theirs,
and varying in diameter from -025 to -035 inch. Each of these rings is composed of a series
of flask-shaped chambers, usually from ten to twenty-four in number, regularly packed side
by side ; the chambers being surrounded by thick walls and
separated from each other by thick, imperforate septa, as is
shown diagrammaticallyin Fig. XXVI, a. Each chamber opens
into the central cavity of the annulus by a single aperture in
the centre of a mamillary protuberance ; this protuberance,
however, is usually nearer to one surface of the disk than
it is to the other (Fig. XXVI, b) ; and it is not always seated
on the internal margin of the ring, but is sometimes a little
removed from it on the surface of the disk, and then points,
not directly, but somewhat obliquely inwards, as shown in
figs. 11, 14. The surface of the annular disks exhibits the
same varieties as that of the pupoid forms, being sometimes
uniform, but more commonly presenting an alternation of
radiating elevations and furrows, the furrows corresponding
to the septa, and the elevations to the intervening spaces
that cover-in the chambers beneath. The number of the
elevations and of the intervening furrows, however, is
usually much greater in these annular forms than that of the chambers ; for the primary
elevation is often itself divided into two ridges by a secondary furrow, especially towards the
outer margin of the annulus ; and thus we have a series of sharply defined radiating ridges
(fig. 13) resembling the teeth of a flat wheel, the furrows between which, however, do not
all extend to the inner margin of the annulus, which may be divided only by those that
correspond to the septa. This ridge-and-furrow arrangement is far more strongly marked
in some instances than it is in others ; a gradational variety being obvious, on the comparison
of a sufficient series of specimens, between the smoothest and flattest of these annular disks
and those whose surface is most unequal. In some instances, moreover, the ridges are con-
tinued along the outer margin of the annulus, so as to give it the appearance of a wheel
toothed at its edges ; and it is curious that this dentated margin is sometimes most strongly
exhibited by disks whose surfaces are the flattest, as is shown in fig. 19. There is a

17

Diagrammatic sections of Bactylopora
annulus : — a, horizontal ; b, vertical.

130 FAMILY MILIOLIDA.

considerable variety, too, in regard to the proportion whicli tlie central space bears to the
breadth of the annulus ; the inner circle being for the most part relatively smaller in the
flattest annuli, and increasing in diameter as the annulus itself swells out and diminishes in
breadth. It is a remarkable feature in this type, which may be distinguished as D. annulus,
that the annulus is usually divided with great regularity into chambers of equal size ; a
regularity 7or which it is difficult to account on the supposition that the entire ring
has been developed by the successive growth of independent chambers. After a careful
examination of numerous specimens, I have only met with one which gives any distinct
indication of a line of junction, such as might be expected to result from the meeting
of the two ends of an imperfect ring completed by the successional addition of new
chambers. And it may therefore be fairly questioned whether the uniform annulus, which
is certainly the normal type, did not originate in a radiating outgrowth of segments from one
large primordial mass of sarcode occupying its centre, in the same manner as the first
annulus of chamberlets in the typical Orhitolites (^ 161) is formed around the primitive disk;
the space at first occupied by the primordial segment being not covered-in by shelly w^alls,
and being perhaps vacated in these annular forms so soon as the surrounding ring of
chambers has been consolidated. We shall hereafter see reason to believe that in the more
complex type of Dadijlopora the central cavity continues to be occupied b)" the sarcode-body
through life, and that it is in this portion that all new annuli have their origin (f 197).

191. In each of the two forms now described a curious variety is occasionally met
with, resulting from what may be termed a " wild "' growth of the segments (such as we shall
frequently encounter in certain forms of the vitreous series), which tends to convert the
closely set, flask-shaped chambers into elongated, divaricating tubes. This is most strongly
marked in the pupoid type, the chambers of which occasionally undergo such an elongation
as to be converted into cylinders (fig. 16) so closely resembling the cells of Ti/biiUpora or
Celh'pora, that, if detached from each other, they might easily be mistaken for fragments of
those Polyzoa ; and, in fact, the determination of this form as a variety of Bactyhpora, under
the designation B. dic/itaia, chiefly rests on its evident relationship to that to be next described.
No specimen has yet been found sufficiently perfect to exhibit the unbroken terminations of
the cells ; but there can be no reasonable doubt that they are closed at their diverging
F XWII extremities (as shown diagrammatically in Fig. XXVII),

hke those of the forms to which they are related. — A

similar tendency occasionally shows itself in a less

marked degree in the annular type (fig. 15); giving

rise to the form which has been described and figured

by Michelin ('Icon. Zooph.,' p. 177, pi. xlvi, fig. 27),

under the name of Cli/peina mar^inoporella, as a member

of the family TuhuUporida. The chambers here also

are elongated and subcyhndrical ; but they remain in

Diagrammatic seetior7z)../^/o^.m^,>,-^«/a,- adhesion to each other laterally, so as to lie obliquely

—A, horizontal; b, vertical; 1, 1, line of to the axis of the ring, and to form a sort of inverted

^™'"'^'^' . funnel, as is shown in the diagrammatic sections in

Fig. XXVIII. The pores represented by Michelin along the external margin have no real

GENUS DACTYLOPORA.

131

walls

Fig. XXVIII.

existence, being merely the result of the attrition of the most exposed part of the
of the chambers ; and the true apertures of the chambers are
seen along the inner margin of the annulus. It is convenient to
retain as the specific designation of tiiis organism the generic
name conferred upon it by Michelin ; so that we shall dis-
tinguish it as D. dypnna* — The resemblance which B. digitata
and B. dypeina bear to tubuliporous polyzoaries is much
strengthened by the deep pittings of their surface, which so
nearly present the aspect of the perforations common in the
shelly walls of the cells of Polyzoa, as to be readily mistaken for
them. It is to be borne in mind, however, that such deep
pittings are not infrequent among the porcellanous Foraminifera
(^ 111, 138) ; and we shall find similar, though shallower, pittings
presenting themselves in other forms of Bactyhjmra.

1 92. Returning now to the ordinary type qID. annulus, we have Diasiammatic sections of DacUj-
next to remark that it is not uncommon to meet with two or more fo^jora c(y;ja«a .— a, horizoutal ;
rings adherent to each other serially by their surfaces (fig. 9); e, venca.
when these surfaces are flat, there will be no spaces left between them ; but when raised into
ridges, the mutual adhesion of these ridges completes the intervening furrows into canals
(Fig. XXIX, a, a). These canals may or may not pass through the entire breadth of the annulus,
according as the furrows by the junction of which they are formed are primary (septal) or are
secondary (intermediate, % 190) ; and even the septal furrows do not always extend to the interior
of the annulus, so that there may be every kind of variety in the size and number of thesg /K»cfera/
interspaces. In what may be considered the typical form of this variety, which is designated
B. reticulata, the symmetrical piling of the rings one upon another forms a compact cylinder,
the exterior of which is marked at regular intervals by single rows of large pores closely approxi-
mated to each other (figs. 17 b, 1 8, c/ a'), and in the intervals between these by the marginal ridges
of the annuli. On the internal surface the annuli are less intimately connected with each other,
as their projecting ribs most commonly stop short of the internal margin of the ring ; and thus •
there is seen a deep grove or furrow (fig. 1 7 b, 5 h') at the junction of each pair, from the peri-
pheral margin of which the junctural interspaces diverge. The apertures (e) of the chambers
{d, d) seldom, if ever, lie in the median plane of the annulus, but are directed more or less
obliquely towards one of its surfaces, so as to appi'oach the furrow just mentioned ; and their
obliquity is sometimes so considerable that they discharge themselves into that furrow. — But
if the surfaces and margins of the rings should be nearly smooth, the pores formed by the
"junctural interspaces" will be very small and inconspicuous ; and when, as often happens,
these are filled up by fossilizing deposit, the composition of the column will only be indicated
externally by the constrictions which it exhibits at intervals. In other cases, again, the "junc-
tural interspaces'' are of extraordinary size.— It not unfrequently happens that the cavities
of the chambers are laid open by attrition (fig. 17 b, c' c')) at the parts of the surface [c, c)

* By Messrs. Parker and Rupert Jones the specific designation marginoporella was the one
employed ; but this is so obviously inappropriate as to render its retention undesirable.

132 FAMILY MILIOLIDA.

where their walls are thinnest ; and such specimens, worn down to the line 1, 1, in Fig. XXIX,

will present a series of large pits or openings between the rows of " junctural interspaces.'' This

seems to be the condition of the form described by Defrance (xxix, torn, xxv, p. 287), under

the name Larvaria reticidata ; and as there is here nothing

Fig. xxix. inappropriate or deceptive in the trivial name, we retain it

to distinguish the form of Badi/lopora now described. The

f'^i^' '5^rirK close relationship between this type and the preceding is

/ Ws>^\ T^^ ( evident.not merely from the general identity in the composition

ckSS^^ ^-"-"—iS^SS" of each annulus, but also from the circumstance that the

)C ^/f ?^°*^( average number of chambers which it contains is the same in

aSSiSI — ' W«s«wf -^- reticulata as it is in I), annulus, and that the average

Xf^y? ^^y diameter of the cylinder of the former is the same as that

\^^~J- — - L_!-^^ of the rings of the latter. There is, in fact, every gradation

between those disconnected rings, which are not unfrequently
Diaarrammatic vertical section of Z'fft'/y- r i i- i i it • ■ i ^i i <•

loporaretic^.lata:-a,a,a,a,\.^r.A^:x^\ found shghtly adherent m pairs, and the compact column of
interspaces; 1, ], line of attrition. which the original annulation is but very imperfectly indi-

cated on the surface. It is to be noticed in some of the most
compact specimens of this type (fig. 21) that the succession of the chambers in the adjacent
rings is not altogether regular, but that they in some degree alternate with each other, so as to
present a transition to the next variety ; and even when the annular divisions are well marked by
the rows of large "junctural interspaces,'' these divisions are sometimes considerably inflected.

193. A modification of this simple type sometimes presents itself, in which the chambers

are more than usually isolated from each other ; each being surrounded on all sides by its own

proper wall, and "being connected with the adjacent chambers by projections of that wall '

(Plate X, fig. 25) ; between these projections are left "junctural interspaces" ij), h), which are

sometimes passages of considerable size (fig. 28), and are sometimes narrowed to mere pores

(fig. 26, 27). The apertures {a, a) of the chambers are here uniformly central, and are seated

on nipple-shaped prominences (figs. 25, 26, 28). The external surface of the walls of the

•chambers, in well-preserved specimens, is roughened by an irregular sculpture (fig. 27) ; a

circumstance of interest with reference to the nature of the original surface in D. ci/Iinclracea.

The piling of these chambers one upon another is not, as in D. reticulata, in distinct annuli ;

for, although they usually form tolerably regular rows, the chambers in successive rows alternate

with each other, those of one row lying in the hollows formed by the convexities of those in the

rows above and below. — This seems to be the Microzoon figured and described by M. D'Archiac

('Mem. Soc. Geol.,' 1850, tom. iii, p. 407, pi. viii, fig. 20) under the name Prattia glandulosa ;

and as there can be no reason to regard it as anything else than a modification of the ordinary

type of Bactyhpora (approaches to the alternating arrangement of the chambers being not

unfrequently met with in B. reticulata^, it will here be distinguished as B. glandulosa.

194. We now arrive at the type on which the genus Bactyhpora was founded, the
B. cylindracea of Lamarck ; which presents a very marked dissimilarity to all the preceding,
both in form, superficial aspect, and internal arrangement ; and yet it will be shown to be
not so far removed from them in the essentials of its structure, as to require being ranked in

GENUS DACTYLOPORA. 133

a different category. A completely developed specimen of this organism is usually rather
barrel-shaped than cylindrical ; and it is in the more attenuated varieties (on one of
which, presenting a difference of superficial characters that will be shown to depend merely
upon the degree of attrition to which the specimen has been subjected, Defrance founded his
genus Poliitri/pe) that the cylindrical form is most pronounced. The specimen of I), ci/lin-
dracea figured by Defrance (xxix, ' Zooph.,' pi. xlvii, fig. 4) measures nearly half an inch
in length, and one sixth of an incli in diameter at its largest part ; but the largest specimens
which have fallen under our observation are by no means of these dimensions ; and we have some
that are quite perfect as to form, the length of which does not exceed one sixteenth of an inch.
The extremities are rounded off by an inflection of the wall of the cylinder towards its axis,
so as partly to close-in the cavity ; there always remains, however, a large central orifice, at
least at one termination ; but whether this is maintained throughout life at both ends we are
not able to speak positively, the figures of Defrance indicating a complete closure at one end,
which none of our specimens exhibit. Notwithstanding the very considerable diversities in
internal structure which (as will presently appear) are exhibited by different varieties of this
organism, the external surface presents the same characters in all ; being covered with a series
of somewhat funnel-shaped cups, at the bottom of every one of which (usually, but not
always, in the centre) is a circular pore (Plate X, figs. 20 a, 29,(7, .</)• The superficial edges of the
dividing partitions between these cups, in the specimens which show least evidence of having
been altered by attrition, are roughened by a sort of rude sculpture, which reminds us of that
of the outer surface of the chamber-walls of Z). c/landidosa (fig. 27) ; and this circumstance seems
to indicate that we have here the normal exterior of the organism, and not (as was supposed
by Messrs. Parker and Rupert Jones, lxxix) a surface produced by the wearing-away of the
outer walls of cavities that were originally closed or nearly so. The pores in these cups are
the orifices of a system of radiating passages that constitutes the peripheral continuation of the
"junctural interspaces;" and it is in the extraordinary development of this "interspace-sys-
tem," and in the formation of a sheath of solid shell-substance (often of considerable thickness)
around the chambered cylinders, that the distinguishing peculiarity of D. ct/lindracea consists.
The degree of development of this solid sheath, and that of the " interspace-system," vary
greatly in relation to that of the chambered cylinder ; but they always correspond so closely
the one to the other, that it is impossible not to recognise in this " interspace-system" the
representative of the " canal-system" of the larger hyaline Foraminifera, and in the solid
sheath the analogue of their " intermediate" or "supplemental skeleton " (1 63). This dif-
ference, however, although one that greatly modifies the aspect of the walls of the cylinder as
they show themselves in transverse section, is not really of so much account as a very remark-
able diversity in the relations between the " interspace-system " and tlie cliambers ; a diversity
that seems at first sight of so fundamental a nature, as to justify the belief that the specimens
which exhibit it must be formed on plans which are essentially unlike. I have succeeded,
however, in tracing these differences so gradationally, not only through an extensive series of
distinct specimens, but through the different parts even of one and the same, that I can enter-
tain no doubt of their being all varietal modifications of a common type ; and much of the
perplexity at first caused by them disappears, when it is remembered that the " interspace
system " is not a definite fundamental part of the organism, but that it is an indefinite residue
(so to speak) left by the non-consolidation of certain passages which seem to be left for the

134 FAMILY MILIOLIDA.

extension of the sarcode-body (which probably occupies the whole cavity of the cj'linder)
through the thick layer of solid shell-substance that ensheaths the chambered portion.

195. In what we may consider the simplest form of B. ci/Undracea, represented in Plate
X, fig. 20, the wall of the cylinder is but little thicker than the length of the chambers ; the
solid sheath and the " interspace-system" being but slightly developed. The relative position
of the chambers is the same as in B. reticulata ; but instead of each chamber opening at once
into the general cavity of the cylinder, it is received into a "junctural space" (an arrangement
of which we have already seen an indication in D. reticulata) ; and these "junctural spaces"
form annular rows of large open mouths upon the interior of the cylinder (as in fig. 24).
The large "junctural space" terminates where it embraces the nipple-shaped aperture of
the chamber, just in the manner that the vagina terminates where it receives the cervix uteri ;
but instead of being a closed cul-de-sac, it gives off a radiating series of tubular passages (fig,
22, b, h) which pass towards the surface in close proximity to the proper wall of the chamber
(as in fig. 24), and terminate there in the funnel-shaped depressions already mentioned.
This condition presents itself only in small specimens, in w-hich the number of chambers
in each annulus does not much exceed that which we meet with in D. unnulus and B. reti-
culata. Some of these specimens are differentiated by the presence of a circular gallery
passing between each annulus of chambers and the internal margin of the cylinder-wall
(fig. 20 B, «, a), so as to connect with each other all the "junctural interspaces" of the same
annulus ; and it is easy to see how such a gallery may be formed by an endogenous addition
of shell-substance, arching over a furrow left at the junction of the annuli (as in B. reticulata,
\ 192), and thus inclosing a stolon of sarcode which (as there is strong analogical reason
to suppose) would unite together the separate radiating stolons proceeding to the chambers
through the "junctural interspaces." But further, in the larger and highly developed specimen
of which a portion is represented in fig. 24, a, we find this coalescence still more complete ; for
the pouting orifices which project into the general cavity of the cylinders open at once into a
wide gallery (shown in vertical section at a , a, and in horizontal section at a, a, a) of uniform
diameter throughout ; whilst on the peripheral side of this gallery there are a number of small
apertures, of which some lead to the chambers b, b, whilst others (of which there seem to be
two to each of the preceding) form the commencements of the " interspace-systems " of di-
verging canals cl, d, that terminate in the funnel-shaped cups c, c, on the surface of the cylinder.

196. Returning now to the simpler type in which the internal orifices of the "junctural
intei'spaces " remain distinct, we find that the diameter of the cylinder may be greatly
augmented by exogenous deposit around the chambered portion, so as to add a solid wall of
great thickness to its exterior. The whole thickness of this wall is traversed by the " inter-
space system " of passages, which end on its surface in the ordinary mode ; these passages do
not ramify or divaricate, so that their number does not augment as they diverge from each
other radially ; but in proportion to the separation which thus takes place between their
surface-terminations, the diameter of the cup-shaped depressions increases. In the specimens
■which are distinguished by the greatest development of this exogenous deposit, a most
remarkable modification presents itself in the position of the chambers ; for instead of lying
on the peripheral side of the internal orifices of the "junctural interspaces," they are disposed

GENUS DACTYLOPORA. 135

(very much as in B. clupcina. Fig. XXVIII, b) so as to lie in the cylinder-wall, between the
successive annuli of those orifices (fig. 29) ; each chamber a, a, opening by the usual contracted
neck and narrow aperture into its corresponding " junctural interspace " h, h, at a little distance
from the internal orifice of the latter. Each "junctural interspace " is here a large cylindrical
passage (f, c), which runs sometimes transversely, sometimes obliquely, towards the external
surface ; the former being for the most part its direction in the median portion of the cylinder,
and the latter towards its extremities. When, as sometimes happens, the direction
is extremely oblique, the passage is very greatly elongated. Before subdividing into the
bundle of smaller passages e, e, to which it gives origin, the main passage dilates into a
cul-de-sac [c/, d), which has sometimes an almost globose form, so that it might be easily mistaken
for one of the proper chambers. Here, then, the ordinary relations of the chambers and the
" interspace system " of passages appear to be completely changed ; for the bundles of branch-
ing passages lie altogether apart from and between the chambers, instead of closely embracing
their walls; and the aperture of each chamber lies just within the commencement of the
main passage, instead of being seated at its peripheral termination in the centre of the ring
of orifices leading to the diverging branch-passages. Yet this change is so far from being of
any essential importance, that we find the transition from the one arrangement to the other
presenting itself in the different parts of the very same specimen ; the axis of the flask-shaped
chamber, which may be said to correspond in the first instance with that of the junctural
passage, being gradually bent out of continuity with it, and at last coming to be nearly at a
right angle with it. It seems to be in the largest and most developed forms (which are
unfortunately only known to us by fragments) that this modification is most completely
effected ; and in these a further modification takes place in the shape of the chambers, which
lie in such close contiguity to each other as to be separated only by thin and nearly straight
parallel walls, and to be separated from the general cavity of the cylinder by a wall of
almost equal thinness. It is only in well-preserved specimens of this type, that the true
chambered lining of the cylinder is found ; for in those fragments which have been subjected
to attrition, this part is so entirely removed that scarcely any indication remains of it ; and
the dilated cuh-de-sac of the "junctural passages" may thus be more readily mistaken for
proper chambers.* The external surface, again, may be removed by attrition ; and a very
different set of appearances will be presented, according to the proportion of the thickness of
the exogenous sheath which has been thus removed, as will be readily understood from fig. 29.
For only the cupped exterior may be worn away, and the surface will then present (as at e' , e)
the transverse sections of the clusters of diverging canals which terminate in its funnel-shaped
depressions. But if more has been removed, the cuh-de-sac of the principal passages may be
laid-open, close to the origin of their diverging branches, the orifices of which are seen around
them, as at/. A specimen in precisely this condition is represented in fig. 23. If the
abrasion should proceed further, the diverging canaliculi will be altogether lost, and only the
orifices of the main junctural passages will be seen. It is very easy to imitate the effects
of any degree of attrition by the careful application of dilute acid, either to the internal or to
the external surface ; and in several specimens thus prepared, I have noticed that the solid

* It was by such a mistake that Messrs. Parker and Rupert Jones were formerly led astray in
their descriptions of the supposed varieties D. jjohjstoma and D. bambusa.

136 FAMILY MILIOLIDA.

sheath is divided into tolerably regular areolae by sutural lines, which seem of different texture
from the rest (fig. 30). Each horizontal row of these areolae corresponds to one annulus ; and
the sutural lines which bound it horizontally, divide that annulus from the annuli above and
below. Each division marked out by the vertical lines corresponds to the cluster of branches
radiating from one of the great junctural canals of the interspace-system ; and the shell-
substance which it includes was probably deposited by the extensions of the sarcode-body
which passed through those canals. As no such sutures are discernible in sections, however
thin, it seems obvious that the substance of the shell at the lines of junction must closely
accord with that of the rest, its difference being only brought out by its more ready solubility
in dilute acid. I have noticed in some instances that sutural lines are only distinguishable
between the successive annuli; the portions of the exogenous sheath belonging to each
annulus being entirely homogeneous.

1 97. It is obvious, from the account now given of the structure of this, the most developed
type oiBacfi/Iojjora, that the development of the thick exogenous sheath which is formed around
the chambered portion of the cylinder could scarcely have taken_ place from the isolated seg-
ments of the sarcode-body contained within its chambers ; but that it must have proceeded
from an aggregate mass filling the whole interior of the cylinder. For it appears scarcely
questionable that the " interspace-system " of large canals, with their bundles of smaller
branches, must have been occupied during life by extensions of the sarcode-body ; since the
peculiar structure of the exogenous sheath cannot be probably accounted for in any other
way, than by supposing each constituent portion of it to have been built up by the agency of
one cluster of such extensions ; each of these clusters remaining as distinct from those adjacent
to it, as are the segments occupying the cavity of the chambers themselves. But it is the
distinctive peculiarity of this " interspace-system," that it has extremely little connection
with the chambers ; in this respect differing widely from the true " canal-system " of Calcarina
(in which genus the " intermediate skeleton " attains a development that is unexampled else-
where), the connection of which with the cavities of the chambers is so direct, that it may be
said to be nothing else than a prolongation of these into the parts of the fabric most removed
from them. \n Dacfi/Iopora, indeed, such connection as it has with the chambers seems to be
rather accidental than essential, resulting from the fact that the "junctural canals" and the
apertures of the chambers happen to coalesce near to the point of their common connection
with the general cavity of the cylinder. And it seems to me that we cannot form any other
rational conception of the animal of this curious organism, than by regarding it as an aggre-
gate mass of sarcode, occupying the whole cavity of the cylinder, and in connection, on the
one hand, with the segments that occupy the chambers, and on the other with the extensions
that radiate past them through the exogenous sheath beyond.

198. Affinities. — Looking at the most complex and specialized forms of Bactylopora, we
should not easily recognise in them any but a very remote affinity to either of the porcellanous
types hitherto described. But the true "idea"' of its structure is to be looked for in its
sin^ler forms ; and, as already pointed out, there is much in the structure of B. annuhs that
reminds us of that of a single annulus of Orhitolites. If, in fact, the segments were united by
internal continuity instead of by external, and if the new rings were developed from the

GENUS ACICULARIA. 137

margins of the old, so as to form an expanded disk, instead of being piled up one above
another, so as to form a cylinder, we should have the essential features of the simple type of
Orbitolitcs. — It may be conjectured, without much improbability, that Dactylopora is only a
single representative of a group whose various forms filled up the hiatus which at present
intervenes between itself and its nearest allies among the ordinary Foraminifera ; one such
link, indeed, we shall presently find in the comparatively simple type to be described under
the name Acicularia.

199. Geographical and Geological Disfribution. — The recent forms oi Dacfi/lopora,\i\\\ch
all belong to the simple type D. enica, have not been met with anywhere save in the tropical
seas ; and the fossil forms are for the most part limited to the Eocene Tertiaries of the Paris
basin, though D. reticulata occurs in the Tertiaries of Italy and San Domingo.

XII.— AcicuLAKiA (Plate XI, figs. 27—32).

200. History. — The history of the genus Acicularia, first instituted by M. D'Archiac in
1843 ('Mem. Soc. Geol.,' tom. v, p. 366), is scarcely less singular than that q{ Bantylopora.
The genus was founded upon certain minute bodies detected by M. D'Archiac in the
" calcaire grossier," the narrowness, elongation, and occasional pointedness of one extremity
of which gave them some resemblance to a needle ; and the place assigned to this type by
its discoverer was among the composite organisms now distinguished as "polj'zoaries." In
this he was followed by Michelin, who repeated his figure of it ('Icon. Zooph.,' p. 176, pi. xlvi,
fig. 14) ; but M. D'Orbigny in the second volume of his ' Paleontologie Stratigraphique '
published in 1850, ranked it in the Foraminiferous genus Ovidite-s, in close approximation
to Baciyhpora ; and in this determination he has been followed by Pictet (' Traite de Paleon-
tologie,' tom. iv, p. 484), who still, however, regards Acicularia as generically distinguished
from Ovidites proper by the pointedness of one of its extremities. By Bronn, on the other
hand (x, bd. i, p. 11, bd. iii, p. 166), it seems to be thought more probable that Aciadaria is
a peculiar form of sponge-spiculc ! We shall see that a careful microscopic examination of
this type affords adequate evidence that it is really Foraminiferous in character, but that its
true structure and its position in the series are altogether at variance with the ideas formed
of it by M. D'Orbigny ; since it is, like DactyJojjora, a composite organism made up by the
aggregation of a number of separate and independent chambers, being generically distin-
guished from it, however, by a difi^erent arrangement of those chambers. This fact has been
fully apprehended by Messrs. Parker and Rupert Jones, although they have not yet stated
it pubhcly ; and the description I give of the type is entirely based on the materials which
they have kindly placed at my disposal.

201. External Characters. — The bodies to which the generic designation Acicularia
seems applicable, vary through a considerable range of forms ; being sometimes elongated
cyUnders gradually narrowing to a point at one end, but hollow through the greater part of
their length (Plate XI, figs. 27, 31, 32); sometimes flattened, but still hollow; and

18

138 FAMILY MILIOLIDA.

sometimes so much compressed that their two sides meet, and the internal cavity is altogether
obliterated (figs. 28, 29). In this last type, of which the dimensions are usually considerably
less than the preceding, it is not uncommon to meet with two or more long narrow rods,
adherent side by side, like the frustules of some Diatoms ; and as the rods are usually smaller
at one extremity than at the other, their direction is radiating rather than parallel (fig. 30).
Their surface is marked with large pores, usually disposed with considerable regularity in a
somewhat alternating arrangement ; the direction of this alternation varies, however, in the
different forms, being sometimes transverse, sometimes longitudinal, and sometimes oblique.
Each pore in unworn specimens is surrounded by a broad, slightly prominent lip (fig. 28) ;
this, however, is very commonly lost by attrition, leaving a large circular orifice (fig. 27).
In some instances the chambers to which these pores lead only partially adhere to each other
by their external walls, "junctural interspaces" being left between them, which mark (as in
Badylojjora glanduhm) their essential dissociation.

202. Internal Structure. — Under whatever form Acicularia presents itself, its structure
is always essentially the same, — an aggregation of separate chambers, more or less closely
packed together. In the cylindrical forms, the cylinder may be considered to be made up
of a pile of annuli resembling those of Bactj/lojjora annulm in every other essential respect
than this, that the chambers open on the external margin of the ring, instead of its internal
margin. They are usually, however, packed more closely together vertically ; and those of
the successive rows alternate with each other, like the cells of a honeycomb, so that there is
no space lost between them, as is well seen in cylindrical specimens of which the surface
has been so much worn away that the chambers are laid completely open (fig. 32). The
aspect of such specimens so strongly resembles that of the most attenuated forms of Dacty-
lopora cyUndracea (^ 194), that the one type might readily be mistaken for the other, if
regard were not had to the fact that in the latter there is a pore at the bottom of every one
of the funnel-shaped depressions (Plate X, fig. 20 a), which does not exist in the former. In
those compressed forms in which the cavity is obliterated and the two sides close completely
together, the inner walls of the chambers will of course meet back to back ; and the same
kind of alternation in the position of the chambers of the opposite surfaces may be then
observed, as is well known to exist in the cells of a honeycomb. In some of the narrowest
of the rod-like forms, there are not, even at their broader ends, more than three chambers in
each series, two showing themselves on one side, and only one on the other ; and the
alternating disposition of these gives rise to the arrangement of the pores exhibited in the
upper part of the composite specimen represented in fig. 30. Towards their narrower
extremities we find the pores arranged in only a single row, as shown in the lower part of
the same specimen ; the chambers of the two sides then alternating simpl}' with each other.

203. Jffinities. — It is extremely curious to trace in this type a reversion to the same
fundamental plan as that on which the simplest forms of Badyhpora are constructed ; the
entii'e composite organism, in each case, being made up of an aggregation of separate
chambers. Of the additional structure which is superinduced upon this, however, in the
higher forms of Badylopora, no trace whatever has- yet presented itself in Acicnlariri. It is
important, also, to observe that in these composite organisms we have another illustration

. GENUS ACICULARIA. 139

of the impossibility of maintaining the existence of a fundamental distinction between
the Monothalamous and the Polythalamous Foraminifera. It was formerly pointed out
(1.52) that there are organisms which although actnalljj monothalamous are jmtcntially
polythalamous : the growth of the single chamber being unlimited, like that of the animal
which forms it ; and nothing being required but the development of septa marking out the
whole body into an aggregation of segments (which we shall see to take place in the parallel
forms belonging to the arenaceous type), to convert such Monothalamia into Polythalamia.
Now in Badijlojxjra and in Acicidaria we have organisms which, though actually polythalamous,
are potentially as monothalamous as the Ovulites to which they were likened by D'Orbigny.
For although the organism, as a whole, is made up of an aggregation of chambers, yet the
absence of any internal communication between these chambers, and the want of any other
external connection than that which is established by the more or less complete adhesion
of their walls, really place them upon exactly the same footing of mutual relationship as that
which might exist among a colony of separate Layence or Orbulince developed by gemmation
from a single individual. It seems quite obvious, that, as in Badyhpora (^ 189), the parts
of the composite fabric must have been brought into mutual relationship by the continuity
of the sarcode-body, which probably extended itself over the exterior of the shell durino- the
whole of life, and added new chambers whenever it had the material to construct them.

204. Geolor/ical Distribution. — It is only, as yet, in the Eocene Tertiaries of France, that
this genus has been found. It is not known to exist at the present time.

CHAPTER VI.

OF THE FAMILY LITUOLIDA.

205. The series of generic forms which there seems reason for bringing together under
the family designation Lituolida, is distinguished from all other types of Foraminifera by
this circumstance, — that whereas we find both in the porcellanous and m the vitreous series
that the individuals of particular genera occasionally exhibit an arenaceous incrustation, this
is simply an addition to the calcareous shells proper to their respective types, and is not a
substitute for it, — whilst in these arenaceous types the investment of the body, although
presenting the regular conformation of a calcareous shell, is really a " test " composed of an
aggregation of particles obtained from external sources, the organic cement by which these
particles are united being all that is furnished by the animal. The group thus constituted
includes a wide range of forms, of which a large proportion have been associated, by the
systematists who have treated of them, with the genera of the vitreous series to which they
respectively seemed most nearly alHed. But, as already pointed out {% 75), the affinities of
the purely arenaceous types are essentially with the porcellanous series, since their animals
can only put forth their pseudopodia from the terminal aperture ; and they are also allied in
the relatively large size of that aperture, in the mode in which the new chambers are added
to the preceding even in the highest forms, and in the incompleteness of the testaceous enve-
lope in those humbler forms which attach themselves, like Nubectdarice, to the surfaces of other
bodies, and are dependent upon these for part of their protection. It is not improbable that
future research may add largely to our knowledge of these arenaceous forms, the special
study of which has hitherto been prosecuted only by Messrs. Parker and Rupert Jones. At
present they appear referable to three generic types ; of M'hich the first, Trochammina, starts
from a rank parallel to that of Cornmpira in the porcellanous, and of Spirillina in the vitreous
series, but has a much wider range of variation in form, and the cavity of which, though origi-
nally unilocular, not unfrequently becomes multilocular by the formation of imperfect septa ;
the second, Liluola, closely corresponds with Nubccidaria in its lower adherent forms, but
ranges in its higher free forms with the " spirilline '' variety of PenerojjUs, and, in the sub-
division of its principal chambers presents a rude sketch of OrlicuUna; whilst the third,
Valvulina, presents features of approximation to certain occasionally arenaceous types of the
vitreous series, not merely in a very close similarity of external configuration, but also in the
primary investment of its body by a thin lamina of shell formed upon the perforated vitreous
type, which is subsequently covered-in by a layer of arenaceous cement-substance, so as to be
rendered actually imperforate.

GENUS TROCHAMMINA. 141

Genus I. — Trochammina (Plate XI, figs. 1 — 10).

206. History. — ^The genus 7'roc^a?»wz«a was first instituted by Messrs. Parker and Rupert
Jones, in 1859 (lxxvii, p. 347), as a sub-genus of Botalia ; on the basis furnished by the
peculiar arenaceous form described and figured by Prof. Williamson (ox, p. 50, figs. 93,
94) under the designation Botalina inflata. The subsequent extension of their inquiries has
led them to separate it altogether from Botalia, and to include in it a large series of arenaceous
Foraminifera presenting very wide diversities both as to form and as to grade of development
(liv, p. 304) ; and it is on their conclusions that the following account of it is based.

207. External Characters and Internal Structure.— Ihe, principal feature that is common
to all the forms of this apparently heterogeneous series, is the peculiar texture of the shell ;
which, although arenaceous, differs greatly from that of other genera whose shells are either
partially or wholly formed by an aggregation of particles of sand. The shell consists of a
dense ferruginous cement of an ochreous hue, obviously composed of an aggregation of very
finely divided particles, in which are imbedded sand-grains of somewhat larger size ; these
last do not project above the surface, which is finished-off like a smoothly plastered wall ; and
thus the shell of Trochammina contrasts strongly with the wholly-arenaceous shells of the other
genera of the same family, and with those partly arenaceous shells which sometimes present
themselves in other genera (as Nubecularia and Miliola), in all of which the sand roughens the
surface, its grains being larger, and the proportion they bear to the cement being greater.
The simplest form of Trochammina (fig. 2) consists of a cylindrical tube, gradually increasing in
diameter, attached by one of its surfaces, and spirally coiled, so as to bear a close resem-
blance in shape, on the one hand, to the cylindrical form of Cornuspira, and, on the other, to
SpirilUna. This form, already described and figured by D'Orbigny (xcii) as Operculina
incerta, and by Prof. Williamson (ex, p. 93, fig. 203) as SpiriUina arenacea, may be
distinguished as Trochammina incerta. Now the undivided spiral tube may form a vertical
spiral, instead of being complanate (fig. 3) ; and the resemblance it then presents to the
" nucule" of CJiara suggests the trivial designation charoides. In a third variety, T.gordialis, the
tube presents in its early convolutions an irregular division into chambers ; its later portion,
however, is undivided, and may either continue to coil in the original plane, or may raise
itself from this and pass over the earlier portion, forming loopings and twistings in various
directions (fig. 4), resembling those of a Gordius. Again, the subdivision into chambers may
become more complete, and the convolutions may assume a more regular disposition ; so that
the shell comes to present a series of lunate flattened chambers, several in a whorl, regularly
increasing with the progress of growth, and communicating by fissures corresponding to those
of Botalia in position, so as strongly to resemble in general conformation the flatter varieties
of B. turbo (fig. 1); this form may be distinguished as T. squamnta. A still higher
development on the same plan (fig. 5), gives the form already noticed as having been
described under the designation B. injlata, which may be regarded as the highest type
of this series. — But returning again to the original undivided cylindrical tube, we find
that this may undergo another series of modifications, not at all less remarkable,

142 FAMILY LITUOLIDA.

constituting the type distinguished by Messrs. Parker and Rupert Jones as T. irregularis.
Thus the tube, which in this type is always adherent, and has a portion of its wall furnished
by the surface on which it grows, may dilate into a large pyriform or oval chamber (fig. 6), of
which also the surface beneath forms the inferior boundary, and which commonly shows a
margined and semioval aperture at the opposite extremity ; and before undergoing this dila-
tation the tube may bifurcate, so as to form another similar tube and dilated chamber. Again,
from the farthest extremity of the first chamber, another tube may proceed, which again may
dilate into a second chamber ; this, in its turn, may put forth another that dilates into a third
chamber ; and thus we may have a moniliform series of ovoidal chambers, connected by cylin-
drical tubes, with every degree of variation as to the number of the chambers, the relative
length of the tubes, and the straightness or curvature of their line of growth (figs. 8, 9, 10).
This type was first observed by Cornuel (' Mem. Soc. Geol. France,' ser. 2, torn, iii, pi. iv,
fig. 37), who described the moniliform series of chambers as eggs of Mollusks ; but its
Foraminiferous nature was recognised by D'Orbigny, who assigned to it the generic name
Welhina, which he also applied to a few-chambered, uniserial, curved form oi Nubecularia (^ 87).
It may undergo a further modification by an alternation in the direction in which the connecting
tubes spring from the chambers ; which gives to the series a loose Textularian character.

208. It is obvious from the foregoing description of the shell, that the primary form of
the sarcode-body is a simple uniform cord or stolon, which may coil itself into a spiral, either
horizontall}^ or veilically, or may take upon itself any other direction ; and that this primitive
imiformity may give place to a differentiation of two kinds, — the spiral cord either undergoing
segmentation, at intervals, by constrictions more or less complete, in such a manner as to show
a tendency to the assumption of the Rotalian form, — or enlarging from time to time by the
accumulation of sarcode at particular points, so as to become converted into the semblance of
a string of beads, more or less closely set together.

209. Affinities. — ^The uniform undivided spiral tube which constitutes the lowest and
simplest form of Trochammina, is obviously allied to the corresponding imperforate spiral of
Cornuspira, the difference between them consisting simply in the material of the shell. But
in the tendency of this type to attain, either by the segmentation or by the enlargement of its
tube, a more or less regular multilocularity of shell, it ranges upwards in a line which may be
considered parallel to Nulecularia, and thus comes to present a near approximation both to
the simpler and to the more typical forms of Lituola, from both which it differs chiefly in the
finely arenaceous texture of its shell.

210. Geographical Distribution. — We have examples of this type from all seas, arctic, tem-
perate, and tropical ; and the simpler of them are found at very considerable depths, the
rotaline forms being apparently littoral, and sometimes occurring even in brackish waters.

211. Geological Distribution . — Simple adherent moniliform Trocliammince, exactly resembling
those which are met with at the present day, are found attached to the surfaces of shells
occurring in the Chalk, and even in the Oxford Clay ; and the spirilline forms can be traced
back through the Gault and Lower Oolite (in which they abound) to the Permian deposits.

GENUS LITUOLA. 143

Genus II.— Lituola (Plate VI, figs. 39—47, and Plate XI, figs. 1 1—14).

212. History. — The genus Lituola-^^% instituted by Lamarck (in the first instance, lviii,
under the designation LifuoJites), for the reception of a minute crozier-shaped shell, common
in the Cretaceous formation, which, resembling SpiroUna (that is, the spiroline variety of
Pencroplis) in external form, differs from it in having its principal chambers subdivided by
secondary septa into chamberlets. The genus has been adopted in its original sense by
D'Orbigny and most other systematists ; but the recent inquiries of Messrs. Parker and
Rupert Jones (lxxix, lxxxi) have led them greatly to extend the application of this generic
designation, and to bring under it a wide range of forms, which not only agree with each
other in the peculiar composition of the shell, but are so closely linked together by continuity
of varietal modifications in all their differential characters, as to evince the intimacy of their
essential relationship.

213. External Characters. — The shell, in all the forms that liave now to be described, is
coarsely arenaceous ; the particles of sand (which may be f ither calcareous or siliceous) being
always large enough to be readily distinguished under a moderate amplification, and generally
giving a very perceptible roughness to the surface. Sometimes, however, the larger particles
are imbedded in a kind of mortar, which, as in the case of TrocJtawmina (^207), seems to be
composed of finer particles, drawn from the like source, united by an adhesive exudation from
the animal (Plate VI, fig. 42) ; and the shell is then very thick and clumsy, deriving its
massiveness, however, entirely from the aggregation of foreign material, and in no degree
(like the arenaceous varieties of Nubectdaria and Miliold) from an abundance of the proper
shell-substance. In other cases, again, the larger arenaceous particles are fitted together in
a very regular manner, without the intervention either of smaller particles or of calcareous
cement (Plate VI, fig. 41) ; so that it would seem as if the animal of Lituola had no power
whatever of excreting calcareous matter for the consolidation of its envelope, but was altogether
dependent for its protection upon its power of drawing to itself and of cementing together
the materials brought to it by the ocean-waters amid which it lives. In its simplest form
(Plate XI, fig. 11) Lituola is a mere string of suboval, plano-convex, successively enlarging
chambers, more or less irregular in outline, attached by their flat side (which is usually
imperfect) to the surface of shells, corals, &c. ; and so closely resembling certain forms of
Trochammina, as, like them, to have been first supposed by Cornuel (' Mem. Soc. Geol. France,'
ser. 2, torn, iii, pi. iv, fig. 36) to be eggs of Mollusks. These two types, however, are readily
distinguished by the texture of their shells. Very frequently this series of chambers com-
mences in the form of a spiral coil (Plate XI, fig. 12), though it afterwards extends itself recti-
linearly or irregularly ; and this is the type which has received from M. D'Orbigny the desig-
nation of Placopsilina cenoinana, under which it has been figured by Reuss (lxxxviii).
These adherent Placopsiline forms are often wild in their growth, spreading and bifurcating
with great irregularity (Plate XI, fig. 14) and to a considerable extent, so as even to attain an
inch in length. The spire, however, may continue to develope itself after a regular fashion,
so that the shell (still adherent by its flat, and usually imperfect side) has very much the

144 FAMILY LITUOLIDA.

conformation of that of Truncaiulina (Plate XI, fig. 13). But we pass from these to a series
of forms in which the shell becomes more and more symmetrical, completing itself on both
sides, and at last detaching itself altogether, and assuming a regular nautiloid form (Plate VI,
figs. 39, 40). This very interesting type is met with at the present time on our own coasts,
and very abundantly in some northern seas ; it possesses so exactly the characteristic form of
Nonionina, that it has been unhesitatingly referred to that genus by Profs. Schultze
(xcviii) and Williamson (ex, p. 34) ; and yet I feel myself bound to agree with Messrs.
Parker and Rupert Jones as to the place they have assigned to it, since, after a very careful
examination, I have satisfied myself that the shell is altogether imperforate ; and that the
animal must therefore differ essentially from that of a Nonionina. The nautiloid spiral, more-
over, frequently gives place, in the fossil forms of this genus, to a rectilineal mode of growth,
so that the shell comes so strongly to resemble the " spiroline " form of Teneroplis as to have
been mistaken for it, the 8jpiroli7ia agglulinans of D'Orbigny (lxxiii, pi. vii, figs. 10, 11)
being nothing else than a Lifuola of which the chambers are undi\'ided. The septal orifice,
in all the foregoing varieties, is single, but varies in form from a simple, roundish passage, on
the one hand to a narrow fissure (Plate VI, fig. 40), on the other to an oblong, lobed, or
somewhat dendritine aperture. It varies also in position ; for whilst in the " nonionine "
varieties it is usually close to the inner margin of the chamber, it not unfrequently moves,
even in them, towards the middle of the septal plane, at the same time becoming more
crescentic (fig. 46), whilst in the straight portion of the " spiroline'' variety it is commonly
central.

214. From these simple varieties of conformation, we now pass to a more important
modification of the fundamental type ; that, namely, which consists in the subdivision of the
chambers by secondary partitions, passing at right angles to the principal septa, as shown in
Plate VI, fig. 44 a, which represents a specimen of the Litiiola nautiloidea of Lamarck, par-
tially laid open by the wearing-away of its outer layer. Now this subdivision varies so much
in its kind and degree in different individuals — being most complete and regular in the largest
forms, whilst it is only present in a rudimentary condition in those which are less developed,
— that its existence cannot be fairly regarded as involving more than a varietal differentiation
of the forms in which it occurs. The extent to which it is carried may be generally deter-
mined by an examination of the septal plane ; which presents a multiplication of apertural
pores corresponding to the subdivision of the chambers. It is worthy of note that in this
labyrinthic variety even the secondary partitions, like the principal septa and the external
wall, are formed of arenaceous material. One other remarkable variety remains to be noticed,
in which the growth is rectilineal from the first (Plate VI, fig. 43), its chambers being sub-
divided, as in the preceding form. This is connected with the preceding by a series of inter-
mediate gradations, in which the " nautiloid " or spiral commencement of the shell bears a
smaller and smaller proportion to its straight or " nodosarian " extension, and at last comes
to be altogether wanting. The septal plane is so extremely convex as to be almost conical,
bearing at its summit the aperture, which is usually composite (fig. 45), or, if single, is a large
dendritic fissure. This peculiar form is common in many Tertiary deposits, and also occurs
in tropical seas at the present time.

GENUS LITUOLA. 145

215. Affinities. — The most intimate relationships which this type possesses, appear to be
imdoubterlly those by wliich it is connected with the other members of its own truly arenaceous
family. Wc have seen how nearly its lower forms approximate to Trochammina ; and, we shall
see that some of its higher are no less closely related to certain varieties of Valmdina. But it
is curious to remark how many types, alike in the porcellanous and in the vitreous series, are
represented as to form by the varieties of tliis single genus. In their attachment by one
surface, the incompleteness of the shell on that side, the indefinitencss of their plan of growth,
and the irregularity of aggregation of their chambers, the lowest forms present a striking
parallelism to Nuhccuhirid ; whilst in proportion as the shell detaches itself and becomes
complete on both sides, it comes to I'esemblc in its nautiloid form and mode of growth the
" dendritine" PcnerojjJis, whilst its crozier-like form is the exact parallel of the " spirolinc"
Pcneroplis. The subdivision of the principal chambers by secondary partitions is an advance
in grade of development corresponding with that which marks the difference between Miliola
and Fahalaria, or between Fmeroplis and OrbicuHna. In its rectilineal mode of growth, the
'■ nodosarine" variety corresponds with the " articuline " varfety of Vvrli-hralina ; but there is
no member, either of the porcellanous or of the vitreous series, in which this plan of growth
is combined with subdivision of the chambers. The types of tlie vitreous series represented
by the several varieties of Lituola in plan of growth and in the form and place of the aperture,
are, as we have seen, Tnmcaf/dina by the most regular of the attached forms, NuuiuHina by
those free, symmetrical, nautiloid forms whose aperture is an elongated slit at the inner
margin of each chamber, and Nndomria by the straight forms with a verv convex septal
plane and central aperture.

216. Geoffraphical Distribution. — The adherent or " placopsihne" varieties q{ Litiiohi, like
their congeners the Trocliawmincc, are inhabitants of our existing ocean, being chiefly
brought up from considerable depths in warmer seas ; the free " nonionine " forms
seem to be common inhabitants of the littoral zone of northern temperate regions ; the
labyrinthic " nodosarine" have been obtained from the neighbourhood of Rio Janeiro, whilst
the simplest forms arc world-wide.

217. Geohfjical Di-sfribiition. — The " spiroline " forms of Liticola are the earliest of which
we have any knowledge ; a minute and simple specimen of this having been found in the
Triassic clay of Chellaston (lv). The " placopsiline" forms have been first noticed adherent
to shells of the Lower Oolite ; and in the Cretaceous period these come to be very abundant.
It was at this epoch that the Lituoline type appears to have attained its greatest development,
as w-e here meet with the nautiloid and spirolinc forms in their greatest number, size, variety,
and complexity. The " nodosarine " form first presents itself in the Miocene Tertiarics of
San Domingo and Malaga, and in the Pliocene of Tuscany ; in which last situation it attracted
the observation of the accurate Soldani, being figured by him (c, pi. xix, fig 92 z, and ci, ii,
])1. 3, fig. cc) under the names of Ortlioceras, Trochiis, and Vermicidm.

19

146 FAMILY LITUOLTDA.

Genm III.— Valvulina (Plate XI, figs. 15—26).

218. Histor//. — The genus Valvulina was established by D'Orbigny (lxix) to compre-
hend a group of multilocular shells, some fossil and some recent, which are distinguished by
their turbinoid mode of growth, and by the partial occlusion of the single aperture of each
chamber by a peculiar valve or tongue that projects from the umbilicus. The genus has
of late been carefully studied by Messrs. Parker and Rupert Jones (lxxix) ; and the account
which I give of it may be considered as virtually theirs, while the illustrations of it given
in Plate XI are drawn from typical specimens with which they have kindly furnished me.
All the forms which they consider properly to belong to this genus are arenaceous ; but
several were included within it by D'Orbigny, which they consider to be varieties of Rotalia
turbo and R. repanda.

219. External Characters and Internal Structure. — ^The impossibility of drawing definite
lines of demarcation between even the primary groups of Foraminifera is remarkably shown
in the type before us ; shice, although its shell is constantly arenaceous and is (for the most
part) jisrr/c/'icft//^ imperforate, yet it is formed on the basis of a perforated vitreous lamina,
which is sometimes brought into view at the apex of the spire by the rubbing away of the
arenaceous incrustation, and which also occasionally displays itself (especially in the large
depressed variety) in the walls of the last-formed chambers (fig. 22), these having not yet been
thickened to the same degree as the preceding by the aggregation of foreign particles. Thus
in regard to the fundamental texture of its shell, Valvulina is obviously related to the vitreous
series ; and we shall see that to certain genera of that series its affinity in general characters
is so close, as to render doubtful the propriety of its separation from them. But whilst the
shells of those genera are often so arenaceous as strongly to resemble those of Valvulina, the
fact that they are often entirely free from arenaceous incrustation shows the animal to possess
the power of forming a regular shell of the ordinary vitreous substance; and their pores may
generally, if not always, be distinguished, on a careful examination, in the intervals of the
attached sand-grains ; so that the exit of their pseudopodia is not interfered with. In Valvu-
lina, on the other hand, the arenaceous incrustation consists not merely of sand-grains
attached to the proper testaceous lamella, but, as in the case of Lituola and Trocliammina, of
a cement formed of very fine particles, in which larger grains are imbedded ; and b)' this
cement, wherever it is present in any amount, the perforations are so effectually closed-up,
that the shell becomes actually imperforate, excepting in the wall of its last-formed chambers.
Hence we have considered that the place of this genus is rather in the Sub-Order Imperforata
than in that of Perforata; but it would, perhaps, be more correct to assign to it an indepen-
dent position as the connecting link between the two.

220. It is more easy in Valvulina than in the two preceding genera to refer all the
principal modifications to one central type ; the Valvulina triangularis of D'Orbigny being the
form of which the rest may be regarded as varieties. This is a triserial, three-sided, pyra-
midal shell (Plate XI, fig. 15), having three chambers in every turn of its spire, and presenting

GENUS VALVULINA. 147

on the convcxit}- of its last chamber a large circular aperture, to which is applied a circular
flap or "valve" of rather smaller diameter, so as to leave a fissure which would be completely
circular but for the tongue-like process which connects the valve with the umbilical margin of
the aperture. The shell may lose its trifacial compression, and assume an ordinary trochoid
or conical form, without any departure from the triserial arrangement of its chambers. This
form is sometimes extremely depressed, becoming so flat as to resemble a Rofa/ia (fig. 16); '
and its aperture is narrowed to an irregular slit (fig. 23), the valve being reduced to a slightly
raised lip along its umbiUcal margin. Such a form has been described and figured by Prof.
Williamson (ex, p. 55, figs. 114, 115) under the name ILotalina Jmca. It is distinguished
from Rotalia not only by the arenaceous character of the shell, but also by the uniformity
with which each circuit of the spire is completed by three chambers, the last three being
always exposed at the base of the cone. This depressed conical form attains a larger size
than any other, and is the one most widely distributed. The cone varies considerably in its
proportions, but always exhibits at its apex a relatively large, globular, primordial chamber,
which is sometimes separated by a slight constriction from the chambers that succeed it.
The preceding is often accompanied by a more aberrant variety, in which the triserial
arrangement is altogether wanting ; and the several chambers of which the shell is composed,
failing to make even a single coil of the spire, form an obliquely semioval shell, having a
broad, flat, oblique apertural plane, with a very large aperture, and a valve of extraordinary
dimensions (figs. 21, 24). The crescentic fissure that surrounds the valve is crossed by
numerous processes of shell, which pass from the margin of the valve to that of the aperture,
and is thus converted into a series of separate passages ; and the valve being itself perforated
by large pores, the entire apertural surface has an almost cribriform aspect.

221. Another series of varietal forms results from the substitution of a new plan of
growth for the original triserial arrangement, and the consequent entire departure in the last
formed portion of the shell from the triangular form which its earlier portion exhibits. Thus,
the proper " valvuline " may give place to a " bulimine '' succession of chambers, the spire
becoming rounded to the form of that of a Bulhnm, and each coil being made up of several
oblong, parallel segments (fig. 25). The characteristic form of valve in this variety is a tongue
or flap formed by a curved prolongation of the turgid lip of the aperture (fig. 19) ; but this
is frequently modified so as to give place to other forms, such as those represented in figs. 20, 2().
In some specimens of this variety the early triangular growth is so completely masked, that
it is by the presence of the valve alone that they can be distinguished from the sandy forms
of Bulimina. — Again, the proper " valvuline" fonii may give place to an elongated, nail-like, or
" claviform " shape ; and it is on this modification, occurring not merely in Valvulina, Taut also
in Textularia and Uvigerina, that D'Orbigny has founded his genus Clavnlina. In tlie clavi-
form Valwlina we find the primitive triserial arrangement of the chambers replaced by a
uniserial, with little or no progressive enlargement of the chambers ; sometimes with a
marked distinction in external form, the uniserial portion being cylindrical, or nearly so
(fig. 17); but sometimes with a retention of the triangular shape, which is here due to the
triangular form of the chambers, the angles of which are strongly carinated (fig. 18). The
mouth in cither case is terminal, and is usually furnished with a regular valve (fig. 17, a).
A still more aberrant claviform variety is occasionally met with, in which the uniserial

148 FAMILY LITUOLIDA.

chambers are pentangular, with five prominent carinae. And it is finally to be noticed that
claviform specimens occasionally present themselves, in which the primitive tvisevial arrange-
ment cannot be distinguished, so that nothing but their aperture indicates tlieir " valvulinc"
character.

222. Afflnities. — It will be evident, from what has been already stated, that if Valvidinu
is to be ranked among Lituolida, it must be regarded as a very aberrant member of that
family ; its afiinities being at least as close to the occasionally arenaceous members of the
vitreous series, as they are to the typically arenaceous Lituola. In fact, it w'ould be difficult
to adduce a more apposite illustration of the indefiniteness that characterises the boundaries
of even the primary subdivisions among Foraminifera, than that which is afforded by the
singular combination of characters which this genus presents, and by the approximation to
that combination exhibited by certain aberrant modifications of such genera as Textularia and
Bulimina, whose proper place is unquestionably among the vitreous-shelled Foraminifera.
Points of resemblance are not wanting, however, between Valvulina and certain porcellanous
types : thus in the tendency of the spiral growth to give place to rectilinear elongation, even
at a very early stage, we are reminded of the articuline elongation of Verfehralhia ; while the
partial occlusion of the large aperture by a valvular flap (of which the small genus
Sphceroidina and some varieties of Hotalia present the only examples in the vitreous series)
is a remarkable link of affinity to Miliola, which is strengthened by the parallelism w-e have
seen to be exhibited by the most developed forms attained by this valve in the two genera
respectively.

223. Geofjrapliical Dislribulion. — The typical form of Vnlviilina is less common at the
present time than it seems to have been at earlier periods ; and the genus is now
represented rather by its trochoid, clavuline, and other modifications. The former present
themselves in all seas, being of smaller size and less frequency in the northern than in the
southern ; and it is along the Australian shores, and in shell-deposits among Coral-reefs, that
we meet with the highest development of the trochoid and of the large-mouthed forms, whilst
the clavuline occur not merely in the Australian but in the Indian and Atlantic Oceans, in the
Red Sea, and in the Mediterranean.

224. Gcolofjical BiMribution. — The earliest specimens of this type at present known
occur in the Cretaceous period ; but it is in the Eocene Tertiaries of the Paris basin that it
seems to have first attained a high development, both as to number and variety of forms. It
appears- to have continued as a common inhabitant of the littoral zone through the successive
periods of the Tertiaiy epoch ; and the assemblage of forms presented by the Grignon
deposits is almost exactly paralleled by that which may be collected at the present time near
the coast of Australia.

CHAPTER YII.

OF THE SUB-ORDER PERFORATA.

225. A very large proportion of these types of Foraminifera which present themselves
to general observation, — including nearly the whole of those inhabiting our own shores, with
the exception of the 2JilioUe, — belong to that division of the Foraminifera which is charac-
terised by the possession of a shell perforated by tubular openings for the exit of pseudopodia.
The reasons already specified (Chapter III) appear to justify us in ranking this division as a
Sub-Order, equivalent in value to the "imperforate" division (^ 75) ; but whilst the subdivision
of the latter into families may be very naturally based on the differences in the material of
the shell, no such characters are available in the present case, the shell being everywhere
calcareous, and being composed of vitreous or hjaline substance, except in a small group in
which it is occasionally, but not essentially, arenaceous. Notwithstanding the very close resem-
blance in external form and in general plan of growth (sometinjes amounting to absolute
ixoiiwrpliisw), which often presents itself between the members of the " porcellanous" and of
the '•' vitreous" series {% 67), there is no real gradation between them. Such a gradation does
exist, however, between the " arenaceous" forms of the Perforata and the Imperforata
respectively ; for whilst, as we have just seen, it may be doubted whether Vnkmlina, in spite
of the essentially arenaceous composition and imperforation of the external test in its fully
developed condition, should not rank among the former in virtue of the perforated hyaline
layer of shell which immediately covers its sarcode-body, there seems almost equal reason
for ranking among the latter some of those TexhdaricB, in which the pores, large and distinct
as they arc in the original shell, seem entirely )ilocked-up by arenaceous incrustation.

226. But although we do not find in this Sub-Order any such well-marked differences
in the material of the shelly envelope, as those which serve to characterise the families of the
Imperforate series, yet it does not seem very difficult to group its diversified forms around
certain principal types, so as to assemble them into Families, of which the members are recog-
nisable by their mutual relationship, and by their essential dissimilarity (except in the border
forms) to those of other groups of equal rank. It is not possible, in the present state of our
knowledge, to separate these families by precise definition ; for they arc so connected with
each other by, intermediate forms, that any definition which should be founded upon the

150 OF THE SUB-ORDER PERFORATA.

characters of the central types would have to be so greatly modified for the compi-ehension
of the peripheral, as to lose all its precision. And all that can be here attempted will be to
point out what seem to be the typical peculiarities of each group, and to trace the shading
off of these as wc pass in different directions from its central t)^pe towards the most aberrant
modifications which it may present.

227. Starting in the first instance, as in the Imperforate series, from the laonollialioiious
forms, we find among these a diversity of shape scarcely inferior than that which we have
seen to exist between Gromia, Squainulina, Cormif^piru, and Troclianimiiw. For in Orbtdina we
have a perfect sphere, not only devoid of any projection whatever, but very commonly
destitute of any principal aperture ; in ■ OviditeSy an egg-shaped spheroid, with an aperture at
each end ; in Lagenu, a spheroidal body drawn out at one extremity into a projecting neck, at
the end of which the aperture is situated ; whilst in SpirlUhia the' chamber consists of a very
elongated tube, regularly coiled in a flat spiral. There is a yet greater difference, however,
in the texture of these shells, than in their external form ; for the substance of that of Lacjena
is very finely tubular, whilst that of all the others is coarsely porous ; and the surface of
Lagena is almost invariably rendered uneven by regular longitudinal costation, or by some other
kind of symmetrical ornamentation, of which we scarcely find any traces in the others.
Moreover Lugma is distinguished by the peculiarity of its aperture, which is very regularly
circular, and has an everted lip, whose inner surface is commonly marked by radiating
fissures.

228. Now it is not difficult to find a series of generic forms which naturally build
themselves up (so to speak) on the basis of the fundamental type presented by Lagena. For
if a new lageniform chamber be added by gemmation to the extremity of its predecessor, and
this process be repeated indefinitely in a rectilineal direction, we have a Nodosaria, — a type
which is characterised, like Lagena, by the finely tubular structure of its shell, by its central
radiating aperture, and by its peculiar ornamentation ; whilst a similar gemmation, repeated
along a bent axis, will give rise to a series of forms, more or less curved, but possessing the
same essential characters, bringing us at last to the flattened and symmetrical spiral of
CristeUaria. On the other hand, an oblique alternating gemmation will give us the biserial
Polymorphina or the triserial Uvigerina ; both of which types are manifestly related to Lagc7w
in their essential features, notwithstanding their striking isomorphism with Textiduria and
Vahultna respectively. — Now of the three principal families under which we shall range the
members of the Perforated series, that to which we give the name of Lagenida is unques-
tionably the one which presents the nearest approximation to the Imperforate ; for we shall
find that, notwithstanding the elaborate condition of its shell, even its highest forms agree
with the latter, rather than with the more elevated types of the former, as to the mode in
which the segments are united each to the preceding (^ G2), and in the absence of any trace
whatever either of "intermediate skeleton" or of "canal-system" (^ 63).

229. If, on the other hand, we take Orbtdina as our starting pomt, and look for its
nearest alliances in the perforated series, we -shall have no difficulty in fixing upon Globigcrina
as its connecting link with higher t}'pes : the polythalamous shell of that genus being formed

OF THE SUB-ORDER PERFORATA. 151

by an aggregation of globular segments that arc united to each other by external adhesion
only, each segment possessing its own separate aperture. The shelly walls of the segments
are composed of a coarsely porous substance, having little or no surface- ornamentation ; and
the aperture which leads to their cavity is a simple fissure, usually crescentic in form,
without cither prominence or lip. Now this simple " globigerine " type may develope
itself, as we shall hereafter see, into a very remarkable form {Carpenter in), in which, without
any departure from the essential characters of the original, a high degree of complexity is
superinduced by the enlargement and sub-division of the later chambers (which completely
include the earlier growth), and by the peculiar provision that is nevertheless made for the
maintenance of the direct communication between each chamber and the exterior. But
whilst this is, so to speak, a lateral offset, 'the tendency to a really higher elevation shows
itself in the more intimate union of the chambers, which no longer have separate external
apertures, but open sequentially, each into the one that succeeds it, the last alone having an
external aperture. Now such a series of globigerine chambers, budded forth alternately on
the two sides of a linear axis, becomes a Tcxfularia ; whilst if the succession follows the course
of a spire resembling that of a Bul.imus, a Bulimina is formed. These types accord closely
with Gloherhpna in the characters of their individual segments ; and their low grade of
development is marked, like that of the Laycnida, by the incompleteness of the posterior wall
of the new segment whenever the anterior wall of its predecessor can be used to complete the
enclosure of the chamber, and by the entire absence both of " intermediate skeleton " and of
" canal-system." Yet in some large forms of Teninlaria we find — as in Carpentcria — a partial
subdivision of the chambers into chamberlets, which is decidedly a character of elevation ; but
there is no further progress in that direction, such forms marking the culmination of the
Textularian type.

230. Reverting again to Glohigcrhui, we see in the turbinoid plan on which its chambers
are disposed an obvious foreshadowing of the turbinoid spire which is the essential character-
istic of the Botalian series ; so that nothing more is needed to convert a Ghbigerina into a
Rofalia, than that its chambers shall open successively each into the next, the last alone
opening externally. We shall find ourselves required, by the absence of any natural lines of
demarcation, to group together, under the generic name Bofalma, a. series of forms that present
very wide diversities in grade of development; the simplest presenting but a slight advance
upon Glohigerina ; whilst the most elaborate exhibit the special features of the perforated
series — namely, the double septum between the chambers, the intermediate skeleton, and the
canal-system — in a highly characteristic aspect; the last two of these peculiarities being
nowhere more conspicuous than in Calcarina, which is little else than a modified
Botalia. But whilst the development of the central stem thus takes place on the original
type, that of the branches or oS'sets may follow a very different course. Thus there are low
forms of Bofalia repanda, whose spire is so much flattened out, and whose chambers are so
greatly elongated, that they come to resemble what a SjArillina would be, if its one continuous
vermiculate chamber were partially divided by transverse constrictions. In some of these we
find a tendency to the obliteration of the regular spiral mode of increase by a " wild " growth
of the marginal chambers ; but this substitution of an indefinite for a definite plan is more
characteristically seen in the Plauorbtdine forms, which, commencing on the regular Rotalian

152 OF THE SUE-ORDER PERFORATA.

plan, are subsequently augmented, not only by the addition of new chambers to the wliolc
margin of the spire, but also by a piling-up of similar chambers on its upper surface. In
these m-ervidinc forms there is no advance upon the simple Globigerine character of the indi-
vidual segments ; but we often find the surface of the aggregate mass remarkably modified
by exogenous deposit. A still greater departure from the Rotalian plan of growtli, without
any considerable modification of the characters of the individual segments, presents itself in
the highly composite organisms which will be described under the generic names Tmoporus and
Pohjtreiiia ,• and in the former of these we shall meet with a development of the intermediate
skeleton and of the canal-system, which curiously repeats in that accrvulinc type the like
development which converts a Itotalia into a CaJcarinn.

231. Between the simplest and the most complex of the foregoing tvpes, there is a con-
tinuity not less complete than that which we have seen to exist between the successive types
of the porcellanous series ; and since we nowhere; find in the structure of the individual seg-
ments any considerable departure from the characters presented by those of the Globirjerina
which we- took as our starting-point, wc shall designate the entire series by the title of
Globigerinida.

232. Our third family contains those types of Foraniinifera, the peculiar specialization
of whose structure entitles them to the highest rank in the group, whilst their comparatively
large size and extraordinary multiplication at the early part of the Tertiary period give them a
place of no mean importance as members of its Fossil Fauna. Not being able satisfactorily
to trace this family upwards from an elementary type to its most elaborate forms (although
it is not without relations even to the \ovi\j Globif/erincc), we shall find it more convenient to
group its various members around a type which presents its characteristic features in their
fullest development ; and we select for that purpose the genus Ojjerculinn, which is charac-
terised by the dense tubular texture of its shell, replaced in certain spots by still harder
non-tubular substance, which often forms tubercles or ridges on the surface ; by the symmetry of
its spire ; by the complete investment of the earlier convolutions by the later ; b)"- the narrow
fissured aperture at the inner margin ; by the complete enclosure of each segment in its own
wall, causing a duplication of the septal lamellae ; and by the interposition of an intermediate
skeleton and highly complex canal-system. All these characters present themselves equally
in the genus Nmnmulina, with the addition (in the most characteristic forms of that type) of a
set of chamberlets, derived from the alar prolongations of the principal chambers, between
the successive turns of the investing portion of the spiral lamina. By the subdivision of the
principal chambers into chamberlets, Operculina is modified into Heferosfft/ina ; and by the
substitution of the cyclical for the spiral plan of growth, Uderodegma is converted into
Ci/clocli/j)eus. So far as the metamorphic condition of the shell of Fumlina allows me to judge,
it seems to have belonged to the Operculine type ; its chamberlets being disposed around a
longitudinal axis, instead of in a complanate spire, so as to give it the same relation to
Heterosterjina that Alveolitia bears to OrhiruUna (^ 151). Again, the interposition of secondary
chamberlets (as in the reticulate Nummulites) between the lamelte of shell by which the disk
of Ciji-lochippiiH is successively overlaid, would convert it into Orhiloides : a type which,
though now extinct, formerly rivalled A'/nnmulina in importance. All these types closely

OF THE SUB-ORDER PERFORATA. 153

accord with each other in every point whicli concerns the characters of the individual
segments, and differ only as to the plan in which those segments are disposed. Now, in
Ampliistegina we find the spire unsymmetrical, and the general development inferior, so that
a certain appro.ximation is presented to the Rotalian type. In Pohjstomdla the texture of the
shell is far inferior in density, and the spire is much simpler ; but this type is remarkable for
the large amount of exogenous deposit with which the proper walls of its chambers arc
overlaid, and for the extraordinary development of the canal-system provided for its nutrition.
By the simpler or "nonionine" forms of this type, we seem carried down towards the GIo-
bigerine ; the connecting link being afforded by the genus PuUc/iia, which presents a strong
resemblance to the former, but seems essentially related to the latter.

Such is the grouping which seems most consistent with the present state of our knowledge
of this important division of the Foraminifcra. That it may hereafter require modification
with the advance of knowledge, is by no nreans improbable ; l)ut it may be afl[irmed with
considerable confidence that the principles on which it is founded are correct, and that alike
in the affinities it indicates, and in the separations it establishes, it is a fair interpretation of
the most important facts which a careful study of Nature has up to this time disclosed.

20

CHAPTER YIII.

• , FAMILY LAGENIDA.

232. A more marked example can scarcel)' be found of the contrast between the results
of the system of classification adopted by M. D'Orbigny^ and those of the method followed
in the present work, than is presented by their respective modes of dealing with the members
of the group here brought together under a designation indicative of their essential relation-
ship to that minute Monothalam, which (as we have just seen) is one of the simplest forms
of the "vitreous" series of Foraminifera. It may be freely admitted that no set of charac-
ters can be framed, which should equally apply to all these organisms, and should differen-
tiate them from all other Foraminifera ; but they will be found to be mutually connected by
a strong family likeness in the most essential characters, — those, namely, which are most
indicative of the physiological condition of the animal ; and whilst we find one or other of
these to be shaded off", so to speak, as we pass from each generic type to the next, the persistence
of other features no less characteristic leaves no reasonable ground for doubt. Throughout the
group we find the hyaline or vitreous shell-substance to be possessed of great hardness, and
to be perforated by tubuli of extreme fineness ; in young and feebly developed examples it
is very thin and of almost glassy transparency ; but in older specimens, if well developed,
it is overlaid by superficial deposit, which in general not only adds to its thickness, but
rises into exogenous growths, having the form either of tubercles, of prickles, or most com-
monly of linear <os7«, which almost invariably run in a longitudinal direction, that is, parallel
to the axis of the shell. These exogenous growths, not being perforated by tubuli, have an
aspect that difi^erentiatcs them from the general surface of the shell. The small circular
aperture is situated in the centre of the septal plane, which is more or less prominent, and
is sometimes prolonged into a tube ; and it usually has an everted lip, divided by radiating
fissures into denticulations. These characters are presented in their highest development
by Lagejta ; and we shall see (^ 239, 253) that so perfect a transition exists between that Mono-
thalam and the polythalamous Nodomria, as renders it impossible to doubt the close affinity
of these two forms. From the rectilineal Nodosaria, through the gently curved DentaJhin and
the more strongly curved Jlarz/inuliua, we are led, in a series so jjerfectly gradationnl as to
forbid lines of demarcation from being anywhere drawn across it, to the spiral CrhteUarin,
which may be regarded as the highest manifestation of the lagenoid type. From this central

FAMILY LAGENIDA 155

stem we find a set of offsets more or less divergent, presenting modifications of the typical
characters on which generic distinctions have been founded, but which we cannot
recognise as of higher than varietal importance.

233. Now it is to be observed that notwithstanding the large size and high development
attained by many Nodomiice and Cristdlaria, their plan of structure is so simple as to bear a
stronger resemblance to that of the porcellanous series, than to that of the higher types of the
vitreous. For each segment is simply joined on to the preceding, in such a manner that the poste-
rior wall of the last segment is formed by the anterior wall of the penultimate ; the septal plane
of each segment is only that portion of its ordinary wall which is destined to be included by the
next addition, and is not differentiated in structure from the rest; and the septa dividing the
successive chambers are consequently not double but single. Hence there is not in this type
any vestige of an "intermediate" skeleton, notwithstanding the extraordinary amount of " sup-
plemental" deposit which forms the exogenous growths from the surface of these shells ; and
we find no trace whatever of any canal-system. Notwithstanding, therefore, the strong
resemblance in plan of growth between Crisiellaria and certain members of the Opcrculinc
series, there is a diversity in the most important features of their structure, which is quite
sufficient to mark their essential distinctness.

234. Throughout the series which begins with Nodosaria and ends with Crixlcllarin, we
trace the same characters of shell-substance, the same forms of surface-ornamentation, the
same position of the aperture (modified only in appearance by the curvature of the axis), and
the same tendency to radiation at its margin, — ^the eversion of the lip, however, being for the
most part wanting. In Orthoccrina, with the same uniserial arrangement of the chambers,
we have an absence of radiation at the margin of the aperture, its form and position remaining
normal ; whilst the disposition of the exogenous growths resembles that of the preceding.
In Pol'i/morjiliina, on the other hand, the affinity to the lagenoid type is chiefly indicated by
the central position of the aperture and by the marked radiation of its margin, as well as by
the occasional existence of a tubular neck ; the external ornamentation is so far obsolete as to
be no longer characteristic ; and the plan of growth is biserial. In TJvujcr'nia, whose plan of
growth is triserial, the radiation of the aperture is wanting ; but its lagenoid nature is
marked by its elongated neck and somewhat everted lip ; whilst the ornamentation of the
surface of the shell is highly characteristic.

235. In the classification of M. D'Orbigny, the closelj'-allied genera of this family
are distributed under /b//r different Orders, as follows : —

I. — MoNosTEGUES. Lagcua.

II. — Stichostegues. Glandulina, Nodosarid, Orthocerina, Dcntalina, Frondicularia,
Linguhna, Rimulina, Vaginulina, Marginulina.

III. — H^LicosTiiGUES. Cristellaria, Flabclllna, Robulina, Uvigerina.

V. — ENALLOsxi^GUES. Dimorpliina, Polymorphina.

156

FAMILY LIGENIDA.

The dissociation of closely-allied types, and the approximation of types altogether distinct,
which result from the adoption of this scheme (and which do not less show themselves in the
modification of it proposed by Prof. Schultze, xcvii) will become apparent as we proceed.
The following arrangement of the genera is here offered as more truly representing their real
relationship : —

FAMILY LAGENIDA.
^ Lagena.

Uo'h

oigenna

brthocerina^

Ijinsulina

Rirjuiina

llobul

Nodosariua.

Nodosaiia

Dentalina

Vaginulina

Planuliiria

Marginuliiia

Dinsorpliiiia

CrisloUaria

Polymorphina

I Glaiululina

; > Frondicularia

Flabclliua

Taking Lai/i'iia as the primary form, it is shown to pass directly into Nodosariua, under
which generic designation, are brought together (for reasons to be stated hereafter), no fewer
than lliirtci'j/ forms which have been differentiated as generic by D'Orbigny. -Of these, the
seven which are ranked in the central column differ from each other only in the straightness
or curvature of their axis of growth, fhe transverse or oblique direction of their septa, and
the centricity or excentricity of their aperture. The three in the right hand column differ
from the preceding in the mode of setting-on of the chambers ; and the three in the left
hand column have been differentiated on account of the form of their apertures. The genera
'Poh/morpJiinaim^ Uch/crijiu being related to Logena in their essential characters, but differing
from each other and from Nodomrina in their respective plans of growth, have positions
assigned to them that arc in harmony with their mutual affinities. The small genus
OrtJioceriiia may be considered as a connecting link between Lngctia and the simplest
conditions of Vvigcruin, with relations of its own to Nodosarina.

Genus I. — Lagena (Williamson, Figs. 5 — 32).

236. Hialorij. — The minute flask-shaped Monothalamia which have received from
D Orbigny the designation Oolina, had been so long previously recognised and distinguished,
that it would be an act of great injustice to abandon without good reason the name originally
given to them. An example of them was figured by Soldani (c,ci) under the inappropriate
designation Orthoccra pcrfede gloMuria ; but it was by Walker (ix) that attention was first
particularly directed to them, several distinct forms having been figured under the generic

GENUS LAGKNA. 157

name Serpida, with Lajjcna appended in brac]\ets, apparently as a sub-generic name. Tlic
designation Vermiculum was given to these by Montagu (lxv) ; but some subsequent writers
on British shells went back to the comprehensive term Scrpula .■ whilst others modified
Walker's Lagena into Lur/cnitla. The peculiar modification of this type which consists in the
introversion of the flask-shaped neck (an example of wliich had been figured by Walker) was
distinguished by Ehrenberg under the generic name Entosolcnia. It was not until 1839
that this type was noticed by M. D'Orbigny ; and he seems to have remained in entire igno-
rance that it had been previously described ; no allusion being made in liis latest enumeration
of the genera of Foraminifera (i.xxiv) to the Monograph of the genus Lcifjena published
some years previously Ijy Prof. Williamson (cvi), in which Walker's original generic name
was restored, and the question of the value of specific distinctions in this group first
treated (as I have already had occasion to observe, p. 9) in a truly philosophical spirit. The
identity of Oolina and Lagena has been noticed by Pictet (' Pak'ontologie,' tom. iv, p. 483) ;
who has riot, liowever, substituted the original designation for that of D'Orbigny.

237. External Characters, and Internal Structure. — The typical Lagena is a minute
globose shell with a prolonged neck and terminal aperture, very much resembling a Florence
flask. It is frequently elongated, however, into an ovate form, and may even be pointed at
its posterior extremity, being at the same time so much narrowed as to become fusiform in shape.
In some of the slenderest forms there is a tubular aperture at each end; and such are occasionally
somewhat bent. Like the Entowlenin figured by Prof. Williamson (ex, fig. 32 a) these are
perhaps to be regarded as " double monsters." The aperture at the extremity of the neck is
surrounded by a thickened rim ; this is frequently notched or denticulated so as to form a set
of radiating fissures ; and sometimes the central portion of the aperture is filled up by a plug
of calcareous matter. There is a large fossil I^agena, in which the neck has secondary
tubular apertures arising from it laterally and almost at right angles to the main tube.
The surface is sometimes smooth, but is more frequently marked with elevated costa,
which usually spring from the centre of the posterior extremity, and extend in a meridional
direction towards the neck, sometimes, however, proceeding no further than the equator (ex,
figs. 5 — 14). These costoe vary greatly in number as well as in lengtii; when they are fewest
they are usually most prominent ; and when most numerous they are so closely approximated
as to give a fluted character to the surface. They are distinguished, moreover, from the
general surface, not merely by their prominence, but by their more glistening aspect ; and
this results from the fact that whilst the substance of which the shell generally is composed is
finely tubular, that of the eo-st<e is destitute of tubuli. In the strongly costated forms the
tubuli are generally disposed in rows parallel to the costse ; and sometimes they are limited,
like the costos, to the posterior portion of the shell. There is seldom in the typical LagencE
any considerable anastomosis of the costse, though traces of it are sometimes observable. —
The length of these little shells is generally between l-45th and 1-lOOth of an inch.

238. The apertural tube or neck is sometimes prolonged internally instead of externally ;
and on this introversion the genus Entosolenia has been founded. The propriety of this dis-
tinction, however, was questioned in the first instance by Prof. Williamson (cvi), and still
more strongly by Messrs. Parker and Rupert Jones (lxxxi), who have finally (lxxvi) come

158 FAMILY LAGENIDA.

to' the conclusion that it cannot be maintained as of even specific value, on account of the
variability of the degree of the introversion. It may be so complete that none of the neck
appears externally, the shell having a nearly globular form, and the tube reaching almost to
the posterior extremity of its cavity. On the other hand it may be so partial that the greater
portion of the neck is extruded ; and between these two extremes there are numerous inter-
mediate gradations (ex, figs. 16a, 22, 25 — 28). In the entosolenian as in the ectosolenian
forms, there is sometimes a tube at each extremity ; and occasionally there is a second inter-
nal tube attached to the side of the principal. — The entosolenian form presents a yet greater
variety of external ornamentation than the ectosolenian ; for not only do we find the surface
marked with longitudinal costae, but these costae may be connected by transverse bars, so as
to cover the shell with a regular division into quadrangular areolae ; and this may give place
to a hexagonal areolation, which may be of various degrees of fineness (ex, figs. 17, 18, 29
— 32). In certain cases the globular or ovate form gives place to one more or less compressed ;
and each margin is then usually elevated into a carina or keel. In a curidus variety
noticed by Prof. Williamson (ex, p. 11, fig. 24) the mai'ginal carina contains numerous small
detached cavities like microscopic water-bottles with straight necks, each of which opens by a
minute aperture at the outer edge of the carina. In these compressed marginate forms the
tubuli of the shell usually open for the most part in a broad band along the marginal ridge,
although occasionally thc}'^ are scattered sparsely over the whole surface. In these forms,
moreover, the introverted apertural tube does not project axially into the cavity of the shell ;
but follows the curvature ofj and is in contact with, one of its lateral walls, in some cases
coalescing with it so that the tube is only complete on one side, the other side being formed
by the shell-wall ; and sometimes its direction is more or less sinuous. — The length of the
Entosolenian variety is usually between l-70th and 1-lGOth of an inch, corresponding closely
with that of the typical Larjena when allowance is made for the introversion of the neck.

239. 3Ionsfrositi('s. — Besides the departures from the typical form which have been
already noticed, an abnormalitj^ occasional!)' presents itself in this genus, which is of much
interest, as showing how gradationally it passes into the polythalamous forms of the same
family. Specimens are of no unfrequent occurrence, in which a superadded segment is
attached obliquely to the side of the original one ; but now and then it happens that the
additional segment is formed in the axis of the original one, so as to imitate the mode of
growth of Nodomria. Sometimes the nature of such specimens may be decided by their surface
ornamentation ; their lageniform character being marked by a reticulation never presented in
the Nodosarine group. But if the markings consist of a simple costation or furrowing, such
as is common to both types, the decision may be difficult ; as is the case with certain specimens
found in the Tertiary sands of Bordeaux, rich in Laf/ena and small NodosaricB ; which
specimens, being two-celled and furrowed, may be considered either as young individuals
of Nodosaria hnyicauda, or as monstrosities of Lar/cna sulcata (Parker).

240. Jffinilics. — In the general simplicity of its structure, Lac/ena is related to Orbuliiia ;
differing from that type, however, in the possession of a single definite aperture and of the
prolonged neck on which it is situated, as well as in the more elaborate structure and orna-
mentation of its shell-substance. On the other hand, Larjena is so intimately related to certain

GENUS NODOSARINA. 159

forms of Nodosarina, that they might readily be taken either for their young, or for fragments
of them accidentally disjoined ; and D'Orbigny states that he actually regarded them in this
light, until he found Layena abounding in localities from which Nodosaria was altogether absent.

241. Geographical Bistributiou. — This generic type appears to be pretty widely diffused;
having been found in marine sands from the coasts of Great Britain and Norway, Bombay,
Singapore, Australia, and Patagonia ; and also in dredgings from great depths. Generally
speaking, the largest and most strongly marked Lac/eiue are found at an average depth of
about fifty (twenty-five to seventy-five) fathoms ; the more delicate varieties being either from
shallower or from deejjer water.

242. Geological Distrihdion. — Large examples oiLagena present themselves in the upper
Chalk of Maestricht : but this type docs not commonly present itself until the Tertiary period,
when it is met with abundantly in tlic Grignon and Bordeaux beds ; also in certain Eocene
and Miocene beds of Germany. It occurs, but not abundantly, in the Vienna basin, in the
Sub-Apennine beds, at Baltjik, and in San Domingo. It is very large in the Crag of Suffolk;
and it abounds in the Post-Tertiary clays beneath the fens of Lincolnshire.

Gems II. — Nodosarina (Plate XII, figs. 1 — 7 ; and Williamson, figs. 33 — 67).

243. Under the generic designation Nodomriiia an extensive series of forms will here be
reunited, which have been grouped by D'Orbigny and the systematists who adopt his views,
not only under several distinct genera, but under three different Orders. The propriety
of this reunion lias been insisted upon by Messrs. Parker and Rupert Jones on several occasions
(liv, lv, lxxvi, Lxxviii) ; and although in adopting their views on this point I am chiefly
influenced by my knowledge of the thoroughness with which this group has been studied by
them, yet I feel it right to state at the same time that the results of my own observations, so
far as they go, are so completely confirmatory of theirs, as to leave in my mind no doubt
whatever as to the correctness of their conclusions. Moreover the extraordinary tendency to
variation which is exhibited by some of the commonest forms of this type, has been recognised
l)y several of the ablest systematists who have treated of it, such as LinntEus, Fichtel and
Moll, and Williamson ; the group being one in which, as in Miliola, it is easy enough to esta-
blish generic difl'erences when only a few strongly marked types ai'e contrasted, whilst it
becomes more and more difficult to maintain these, in proportion to the number of indivi-
duals compared, until at last the difficulty amounts to an impossibility. — It will be convenient,
for the sake of avoiding repetition, to state in limine that we regard as the two extreme forms
of this type the straight rod-like Nodosaria and the spirally-coiled Crisiellaria ; the remainder
either forming part of the series by which one of these continuously graduates into the other,
or being (so to speak) offsets fi-om some part of that series distinguished by some peculiar
varietal modification.

244. History.- — Although the generic designations Nodosaria and Cristellaria were first
introduced by Lamarck (lix), yet numerous organisms of the type now Ijefore us had been

160 FAMILY LAGENIDA.

described and figured under other names bv preceding systcmatists. Tiius LuintKus (lxiii),
under the all-comprehensive designation 3««(^//«5, enumerated as distinct species no fewer than
seven Nodosarian forms and one Cristellarian ; pointing out in regard to tlie latter its special
tendency to pass into varieties. Some of the Nodosarian forms were figured and described
by Soldani (c, cl) under the designation Orfhoceratia ,- while some examples of the Cristel-
larian were ranked under Naidili(s, and others under Leniicida. Of the varietal forms of
jS'autiliis {Cristellaria) calcar T[ioi\ce([h\ lAn^nxxxs,, seven distinct -ipeciex were made by Walker
and Montagu (lxv). These varieties, however, with many more, were brought together again
by Fichtel and Moll (xlv), who showed the same right appreciation of the value of subor-
dinate differences in regard to this type, that they displayed with respect to others. Precisely
the opposite line was taken, according to his wont, by DeMontfort (lxvi), who made from the
varieties of Crislellariacalcar no fewer than ihhieen neio fjenera, only one of which has been ac-
cepted by later systematists. Besides introducing the generic names Nodosaria and Crixtellaria,
Lamarck (lix) re\-ived the name Oiihoeera as the designation of certain Nodosarian forms,
and applied the term Lenticuliies to one of the varieties of Crist ell ai- la calcar ; his idea of the
real nature of the genera which he created being so vague, that he assembled under the term
Cristellaria examples of the genera Peneroplis, Polj/stomella, Hotalia, and Plaiwrhidina, in
addition to true Crldellaria ; whilst under Nodosar'ni he actually placed a Scrpidi). The
genus Frondictdaria was created by Defi'ance (xxix) ; and he also erected two of the varietal
forms of Cristellaria into the genera Planularia and Saraceiiaria, of which the former was for
a time adopted by D'Orl)igny, whilst the latter was adopted by Blainville (vi), who also
adopted two of De Montfort's genera, Oreas and Linthuris, and added another of his own,
Crepididina. It was by D'Orbigny,' however, that the greatest number of those generic dis-
tinctions were invented, which have passed into currency on his authority ; his original
' Tableau Methodique' having included Glandidina, Dentalina, Lincjulina, Piinidina, Vnyimdiiut,
Mari/iin/li)ia, Pobidina, and Dimorphina, together with others which he subsequently
abandoned, in addition to the Nodosaria, Urthucrrina, and Cristellaria of Lamarck, and the
Frondicularia of Defrance. The genus Flabcllina was added to the foregoing in 1839 (lxxi).
Of these, thirteen were ranked in his order Sticl/osth/ues, their line of growth being either
straight or slightly curved; three as belonging to the Helicostf'fjuex , their growth always com-
mencing in a spiral, though it does not always continue on the same plan ; whilst one is
disjoined from its congeners and referred to the order Enallosfeyucs, because in its early
growth its chambers seem to alternate on three sides of a central axis. It is acknowledged by
M. D'Orbigny (lxxiii), however, that between Muryiaidina, the last genus qIVx?, Hiichosteyues,
and Cristellaria, the first genus of his Helicosterpies there is " un passage evident; " the most
curved forms of the one passing into the least curved forms of the other; and Prof.
Williamson (ex, p. 25) has expresssed himself as unable to separate these two genera;
remarking that the Cristellaria Berthelofiana of D'Orbigny '• has no greater curvature than his
Maryinida Wchbiana ; and in like manner his C. ci/mboides has even a smaller one than Iiis
J/. /vfffoy;/, or than occurs in numerous other species of the same genus." "The variations
of the two English species of Cristellaria," he continues, " satisfy me that the characters
which distinguish Cristellaria from Margiuidina are insufficient to be specific, much less
generic ones." So, again. Prof. Williamson (p. 22) expresses his conviction that the genus
Vaginidina of D'Orbigny is not reallv distinguishable from Beiilalina ,■ the characters by which

GENUS NODOSARINA. 161

lie differentiated it being presented by mere varieties of the British D. legumen. And he does
not seem more inclined to retain the genus Bobulina, which is founded on varietal forms
of Crutellaria. Thus we see that, in so far as he had the opportunity of making a sufficiently
extensive comparison of these protean forms, he was led to conclusions of the same kind as
those here advocated on the basis of a more comprehensive study of them. In no group is
the artificiality of M. D'Orbigny's method of classification more apparent; and there is none in
which the results of painstaking research have been more fruitful in elucidating the close
natural affinities of organisms, whose diversity of form at first sight appears to require their
wide separation from each other. — It will be convenient in the first instance to describe the
typically straight and the typically sjnral forms of this genus ; and then to notice the inter-
mediate links by which the two are connected, and the chief varietal modifications which
diverge from them in diff'erent directions.

245. NoDOSARiA : External Characters. — The elongated shell of this organism consists
of a series of segments joined end to end in a straight line ; these segments sometimes
exhibit a progressive increase, so that the entire shell has somewhat of a conical form ; whilst
in other cases each segment has the same diameter as the preceding, so that the general
form of the shell is cylindrical ; and it occasionally happens that the middle segment is
larger than those which precede and follow it, or even that the primary segment may be the
largest, and that the size of the succeeding segments progressively diminishes. The pri-
mordial segment is often furnished with a more or less prolonged macro. The segments are
marked externall}'^ by more or less definite constrictions, which are transverse to the axis of
growth ; sometimes these constrictions are simple bands, the successive segments being in
contact with each other over the whole of their septal planes (ex, figs. 3G, 38) ; whilst in
other instances the segments are nearly globular in form and are connected together by
narrow necks, so that the entire series looks like a string of beads (Plate XII, fig. 2).
That such differences have no specific value, is fully proved by the fact that they occasionally
present themselves in the several segmental divisions of one and the same individual. The
septal plane is circular, and the aperture occupies its centre ; that of the last segment is
sometimes situated at the extremity of a long neck resembling that of a Lagena, and is sur-
rounded by a row of triangular denticles (ex, figs. 36, 37) ; but the margin is usually rather
inverted than everted, and such a broad, smooth lip as is common in Lat/ena and in
Vvigerina is rare in this type. Although the surface is sometimes smooth, yet it is more
frequently rendered uneven by longitudinal flutings or ribbings (ex, figs. 36 — 38), or by the
projection of numerous spines from every part of the exterior (Plate XII, fig. 2). The
number and degree of these inequalities are extremely subject to variation ; sometimes the
costse or spines do not show themselves equally on all parts of the shell, and they are gene-
rally stronger on old than on young individuals. — The large Nodosarice of the Sub-Apennine
tertiaries sometimes attain a length of more than an inch ; but tlic recent forms are far
smaller, few of them much exceeding 1-1 0th of an inch in length.

246. Internal Structure. — When the shell of Nndomria is examined by sections taken
in various directions, it is found that the greater part of it is penetrated by tubuH of extreme
minuteness, wliich pass directly fi'om the interior of the chambers to the external surface ; these
tubuli, however, do not extend into thecosta) or thespine.s, which are everywhere composed of

21

162 FAMILY LAGENIDA.

an apparently homogeneous shell-substance. In those forms which have the segments closely

applied one to the other, the outer wall of each chamber partly invests the outer wall of the

preceding, and the invested portion serves as the septum between the two

Fig. XXX. ^pig._ XXX). This septum has the ordinary structure of the outer wall, and

««, is not diiferentiated from it by being non-tubular, as is ordinarily the case

in other shells of the vitreous series ; a point, as we shall presently see,

of some consequence in regard to the position of the aperture in Cristellaria.

The apertures a, «,V/,"«,' between the successive segments correspond precisely

in form and position with that of the last segment «* which is seen externally.

247. Cristellaria : TSxternal Characters. — The typical form of this
organism may be considered as a nautiloid spiral, each wliorl of which has
its chambers extended by alar prolongations so as to reach the centre,
and thus entirely to enclose the pi'eceding whorl. The number of chambers
in each whorl is much smaller than in most other nautiloid Foraminifera, being
seldom more than eight or nine, and often less. The division of the chambers
is always strongly marked externally by septal bands, which are sometimes elevated into
continuous ridges, sometimes into rows of tubercles, whilst sometimes on the contrary they
are depressed ; but they are always differentiated by their peculiar appearance from the
ordinary surface of the shell. The direction of these septal bands is somewhat oblique to
the axis of the spire ; and they are generally convex anteriorly (ex, figs. 52 — 54). They meet in
the umbilicus, which is usually raised into an elevated tubercle. The margin of the shell
often rises into a sort of keel or carina, which may even be extended into a cullro or knife-
blade projection ; and sometimes this gives off a variable number of radiating prolongations
(Plate XII, fig. 3), as in the form distinguished as C. calcar. The surface of the segments
between the septal bands is sometimes regularly marked by ridges passing in the direction
of the ajcis of growth, so as precisely to correspond with those of Nodosaria, as in the
Mobulina ariminensis of D'Orbigny ; whilst it is sometimes studded with little spinous tuber-
cles, as in the R. eckinata of D'Orbigny; and the one condition may give place to the otiier
in different segments of the same shell, as is shown in Plate XII, fig. 3. The form of the
septal plane is sagittate (Plate XII, fig. 3) ; and the aperture, which exactly resembles that of
Nodosaria, is situated at its extreme point, so as to be at the outer margin of the convolution.
When the shell is looked at laterally (Plate XII, fig. 3), however, it is seen that the aperture
is really situated nearly in the centre of the anterior wall of the last segment, as in Nodosaria.
— The diameter attained by the fossil Cristellarice of the Sub-Apennine Tertiaries occasionally
exceeds l-5th of an inch ; the recent examples of this type, however, are usually far
smaller, the diameter of the British specimens not usually exceeding 1-1 5th of an inch, and
being frequently much less.

'' 248. Internal Structure. — The te.xture of this form of shell precisely corresponds with that
of Nodosaria; being very finely tubular, not only in the lateral walls, but also in the septal
divisions between the chambers, which are here strictly continuations of the lateral walls over
the anterior face of the chambers, instead of being completely differentiated from them as in
the higher types of the vitreous series. That the real position of the aperture is nearly in the
centre of the anterior wall of the chamber, is made very apparent by a careful examination of

GENUS NODOSARINA. 163

its relations in a section passing tlirouoh the median plane ; its position, however, is always
more or less outside of the axis of the spiral, so as to be nearest to the convex border. The
elevated septal bands or rows of tubercles, the central umbilical tubercle, the mar^^inal cauna
or culiro with its radiating prolongations, and the longitudinal ribs or scattered spines with
which the surface is beset, are all composed of non-tubular shell substance. No additional
feature of any importance is revealed by sections of the shell. Even in the most highly
developed examples of it, I have not detected the least vestige of a canal-system ; and the wall
of each chamber seems to be simply joined- on to that of the chamber which preceded it, so
that each septum is formed not of two laminae, but only of a single one.

249. Thus the differences between these two extreme forms reduce themselves to these, —
that the axis of growth changes from a straight line to a spiral, that the divisions between the
segments cross that axis obliquely instead of transversely, and that the aperture leaves its exactly
central position to become excentric. Now, among the varied forms of the Cristellarian type,
we meet with every gradation between such as persist in the spiral plan of growth through
their whole lives, and such as, after forming one or more convolutions, thenceforth increase
along a nearly rectilineal axis, still having their aperture at the convex margin. From these
last we pass by an equally continuous gradation (exhibited in the varieties of the single British
species C. suharcuatulu , ex, p. 30) to forms in which the increase is from the first along a line
so slightly curved that the primordial segment remains terminal, as in D(?«ifa//«« ; it was to
these intermediate forms with a central aperture, that the name Marginidina was given by
D'Orbigny. In proportion as they approach the rectilineal mode of growth, they become
more and more like Nodosaria in their general aspect, and especially in the replacement of
the carina or cidtro of the convex margin by a set of longitudinal costa that repeat one
another at regular intervals around each segment, and are continued from one segment
to another, — this being especially the case in those varieties in which the compressed form
has most yielded to the conical or cylindrical, whilst the costse along the two margins are
usually the strongest in the compressed forms, which thus show an interesting link of tran-
sition to certain examples of that modification of Nodosaria which has been distinguished
as' Lingulina (Plate XII, fig. 1). In Bimorphina (the true nature of whose growth was entirely
misunderstood by M. D'Orbigny) the early growth is truly Cristellarian, though the form of
this part of the shell is somewhat spheroidal ; but the direction of the axis suddenly becomes
rectilineal or nearly so, and the aperture, from being on the convex margin, becomes central,
so that the plan of growth is thenceforth truly Nodosarian.

2.50. Returning now to the Nodosarian or rectilineal type, we find that this is subject to
like variations, both as to general plan of growth, and as to minor details. Those varieties in
which the axis is slightly curved, the segmental divisions somewhat oblique, and the aperture
shghtly excentric, — its displacement, however, being towards the concave margin, — have been
distinguished by the generic name Dnilalina (ex, figs. 40 — 44). The variations which have
been mentioned as presenting themselves in the form and mode of connexion of the segments,
and in the superficial inequalities, of Nodosaria, so precisely repeat themselves in Bentalina
(compare together figs. 38 and 42 of ex, or Plates I and II of lxxiii), as to excite surprise that
these two types should ever have been separated, — especially since it is made perfectly clear
by the comparison of a sufiicient number of forms, that a complete gradation exists between

164 FAMILY LA.GENIDA.

the perfectly straight Noclosaria, and the most arcuate Dentalinn. On the other hand, an
increased obhquity of the segmental divisions, accompanied with a lateral compression of the
shell, and with a greater or less degree of curvature of its axis, constitutes the varietal
modification to which the generic name Var/uudina has been given (ex, figs. 45 — 48). When
this form becomes extremely flat and broad, it receives the name Planularia.

251. The form of the aperture, again, is often modified in accordance with that of the
septal plane ; and on this modification (of which we have seen marked examples in Miliola and
in the " dendritine" variety of Peneroplis) other genera have been founded. Thus Lingulina
(Plate XII, fig. 1 ) is nothing but a compressed Noclosaria, whose transverse section is oval, and
whose aperture (fig. 1, a) has undergone a corresponding elongation, sometimes becoming
crescentic or reniform. The low value of this modification as a differential cliaracter is
curiously evinced by the fact, that in the L. mutabilis of D'Orbigny, the last chamber, instead
of being compressed and bicarinated like those which preceded it, is triangular and tri-
carinated, and is furnished with a triangular aperture. In the various forms of Li/ii/ulina,
again, it is curious to see how precisely the superficial inequalities of Nodosaria and Cnstellaria
repeat themselves ; the costate varieties usually having the ribs of the two margins raised into
carinas. — The varietal modification on which the generic term Bimulina has been conferred by
D'Orbigny, is merely a compressed or vaginuline form of Dentalina, in which- the aperture,
instead of being circular and nearly central, is an elongated fissure extending through a large
part of the convex side of the anterior wall of the chamber (Plate XII, fig. 4). — And the varieties
of the Cristellarian type in which the aperture, instead of being round, is triangular (Plate XII,
fig. 3, «), have been distinguished by the generic term Eobulina. The gradational transition from
one form of aperture to the other, is seen in the varieties of the common Cristellaria calcar.

252. Another set of varietal modifications of the Nodosarian type, arises out of the diver-
sities in the mode in which the segments are applied one to the other, and in the degree in which
the later segments extend themselves backwards so as to enclose the earlier. Thus in the
Glandidina, of D'Orbigny, not only is the anterior wall of each chamber prolonged forwards as in
Nodosaria, but the posterior portion of each segment is so far prolonged over the preceding as
to conceal a large part of it (Plate XII, fig. 5). This prolongation is carried to a much greater

extent in the well-marked form known under the designation Frondi-
I'lG. XXXI. cularia ; of which the shell is extremely compressed, and of which the

segments are so prolonged backwards along the two margins, that the
chambers have a sagittate form, the aperture being at the point of each
(Fig. XXXI). The extent of these prolongations, however, varies
considerably ; for sometimes the ahe. of the newer segments meet
beyond the primordial cell, so as completely to enclose it (ex,
fig. 50), whilst in other instances the posterior prolongation is not
greater than in many Glandulina (ex, fig. 51). When the early
growth of this frondicularian variety takes place along a spiral
instead of a rectilineal axis, (Plate XII, fig. 6), it is referred by
D'Orbigny to the genus Flabellina. The relation of this form to
Frondicidaria is precisely that of Cristellaria to Nodosaria .- that
general physiognomy of the two which depends upon the peculiarity of their later growths,

GENUS NODOSARINA. 165

being so strikingly similar as at once to suggest their close affinity, (notwithstanding
that they are referred by D'Orbigny to different Orders) ; and this affinity being distinctly
proved by the existence of a continuous series of gradational forms, in wliich the spiral of
Mabellina uncoils itself more and more, until its axis assumes the rectilineal direction of that
of Frondicularia.

253. Affinities. — The relationship of the universally-rectilineal or slightly-curved Nodosaria
to the unilocular Lagena is extremely obvious; many forms oi Nodosaria being in all essential
particulars Layence, of which the segments that are successively formed by gemmation have
remained in continuity with each other. The intimate structure of their shells, moreover, is
precisely the same; and the surface-marking of the simple is often precisely repeated on the
composite forms. The Cristellarian or fiat spiral forms do not seem to graduate into any other
type, being (so to speak), the culminating group of the series to which they belong ; so that
it is only through its simpler or more elementary forms, that these are related to the genera
to which we have assigned a parallel rank in the family Lagenida.

254. Geographical Distribution. — Under some or other of its protean forms, the Nodosarine
type is very generally diffused through the seas of various parts of the globe. Nearly all these
forms are well represented in the Rhizopodal Fauna of the Mediterranean (liv) ; and the
Adriatic Sea is particularly rich in them, Crialellarice being found there of large size, and in
greater variety and abundance than elsewhere, and Planidaria being almost peculiar to
that locality. The Nodosarines arc not so common in littoral deposits as they are in those of
moderate depth.

255. Geological Distribution. — Not only can the Nodosarine type be traced back in geolo-
gical time to a very remote antiquity — as far even as the Carboniferous epoch — but its leading
varieties are recognisable in the earlier strata, as well as in a succession of later formations.
The Triassic clay of Chellaston has been shown by Messrs. Rupert Jones and Parker (lv), to
contain not merely typical representatives of the Nodosarian, Dentaline, Glandulinc, Linguline,
Vaginuline, Frondicularian, Flabelline, Marginuline, and Cristellarian forms, but also a number
of those connecting links between these, of which mention has been made in the preceding
pages. Similar varietal modifications present themselves in the Foraminifera of this type
from the Lias-clay of England and the Continent (see Bornemann, ' Liasformation, Gottingen').
The clays of the Oolites also are rich in them ; and in the Cretaceous series we meet with a
peculiar abundance and variety of Nodosarine forms. In the remarkable development of the
Rhizopodal fauna which seems to have taken place at the commencement of the Tertiary
period, the Nodosarine type appears to have had its full share, at least as regards the
abundance of individuals and the large size they attained ; but we do not find any well-marked
new varieties. The Vienna Tertiaries present us with an almost complete sample of the entire
series ; and it is in those and in the Sub-Apennine Tertiaries that we find the largest specimens,
especially of the Cristellarian sub-type, that are anywhere to be met with ; the nearest approach
to these at the present time being afforded by specimens collected on the Abrolhos Bank.
From a comparison of the Rhizopodal fauna of the Siennese clays with similar recent collections
from various localities in the Mediterranean, it is concluded by Messrs. Rupert Jones and
Parker (liv) that those clay beds were deposited at a depth of not less than 40, and not

166 FAMILY LAGENIDA.

more than 100 fathoms. The marine Tertiaries of other regions are scarcely less rich in
Nodosarine forms ; so that we may consider this type to have an equally wide diffusion in
time and in space.

Genus III. — Orthocerina (Plate XII, fig. 7).

256. Hisfori/. — This is one of the numerous genera created hy D'Orbigny in 1825 for
the reception of the various modifications of the Nodosarine type ; and it is the only one
which we do not at present see adequate reason for reuniting with the rest, its combination
of characters being so peculiar as to differentiate it from every form of that series, as well as
from the other genera of the family Lac/enida.

257. External Characters and Internal Structure. — The shell of this genus is formed of
a succession of segments arranged in a straight line, without any intermediate constrictions ;
these segments usually increase pretty regularly in size, and are either square or triangular
in their cross section, so that the whole shell has the form of an inverted pyramid, either four-
sided or three-sided, the faces being generally concave (Plate XII, fig. 7). The septal planes
are sometimes nearly flat, but are more often very convex. The aperture, whicii is a simple
circular perforation without radiating fissures or equal and regular denticulations, is somewhat
pouting, but does not generally project as a distinct tube. The angles sometimes become
sharply carinated by exogenous deposit; and thick, rounded, longitudinal costse may exist also
midway between the angles, as in the form designated Hhahdoyonium anomalum by Reuss (xc b),
these, however, being formed rather by the sudden convexity of the walls of the chambers
midway between the carinated angles, than by any great excess of exogenous deposit.

258. Affinities. — This genus is obviously a member of the family Lagenida, to the
composite forms of which it is allied in its general mode of growth, the character of its
aperture, and the disposition of exogenous deposits on its surface. Its nearest relationship
seems to be to certain feebly-developed forms of TJingerina ; but in the rectilineal disposition of
its segments it conforms to the Nodosarian type.

259. Geographical and Geological Distribution.- — ^The only recent example of this type at
present known is that mentioned by D'Orbigny (lxxiii) as having been obtained from the
West Indian seas. So far as we yet know, the earliest appearance of Orthocerina is in the
Oxford Clay ; it is afterwards met with in the Chalk formation and in the Paris Tertiaries.

Genus IV. — Pqlymorphina (WiUiamson, Figs. 145 — 1.57).

260. Historg. — The earliest notice of the shells of this very common but extremely
variable type, occurs in the work of Boys and Walker (ix) ; in which the generic name

GENUS POLYMORPHINA. 1G7

SerpuJa, witli the description tenuis ovalis Icevis, is given to the well-known form afterwards
named by Walker -S*. ladea ; under which designation it has been cited by several among the
earlier writers on British Conch ology. Certain aberrant forms distinguished by the 'stag-
horn' processes to be presently described, were described and figured by Soldaui (ci) under
the name Pohjmorphia corcula spinosa ; and upon his figures of this and certain other forms
of the same type, De Montfort (lxvii) founded his genera Canopus, Cantharus, Misilus, and
Areihusa, of which none but the last has been adopted by any other systematists, and of which
all are now entirely disused. For the objectionable name Serpula, the scarcely less objectionable
name Vermicidum was substituted by Montagu (lxv), who associated under that generic desig-
nation examples of Miliola, Lagena, and Polpiioiyhina ; and this, again, has been adopted by
British Conchologists, though it has not been admitted by continental authorities. The name
Polgmorjj/dna was used by D'Orbigny in 1825 to designate a portion of tiie series of forms
which we now include under that generic type; other portions being separately ranked by
him under the genera Globulina and Gidlidina, which, together with Dimorphina, made up his
family Poli/morpInnidcB. The absence of any valid generic or even specific distinction between
the ordinary forms of Polijmorpldiia, Globulina, and Gidtidina became apparent to Prof.
Williamson from the 'comparison of only the British species which had fallen under his special
observation ; and we can not only entirely endorse his excellent remarks (ex, p. 73,) upon the
specific identity of the forms whicli he brings together under tlie designation Polymor-
pldna ladea, but can extend them also to those other more divergent modifications of which
his P. mijristiformis is an example.

20 1. External Cliaraders and Internal Struciure. — The essential characters of Polijmor-
pJdna consists in the biserial alternation of lageniform chambers, each with a i-adiating mouth,
along the two sides of a longitudinal axis. The form and disposition of the chambers,
however, may vary so much as to give to the entii'e shell such marked diversities in shape,
that, unless tiie intermediate gradations were traced out, there would seem adequate ground
for specific if not for generic differentiation. Starting from what may be regarded the typical
form of the common P. ladea (ex, fig. 145), we observe that the segments are arranged very
obliquely to the central axis, and that each is prolonged in some degree over tlie penultimate
segment on the opposite side (so as to render the shell unsymmetrical), whilst it also extends
itself backwards over the antepenultimate segment on its own side ; the entire shell thus
presenting a somewhat fusiform shape. Now there may, on the one hand, be a greater elongation
of the shell, arising out of a predominance of the forward over the backward g>owtli of the seg-
ments, so as to make the entire shell resemble a wheat-ear or grass-spike ; whilst, on the other
hand, by a predominance of the backward growth of the newer segments, the earlier ones may be
almost or completely concealed by them, and the entire shell may come to present the form of
a drop or a tear (ex, figs. 147, 153 — 155). Again, its two opposite surfaces may be more or
less compressed ; and this compression may proceed to such an extent that tlie proportions of
the shell resemble those of a thick fleshy leaf. The most remarkable departure from the
ordinary type is seen in those forms in which the last chamber extends itself over all the
preceding, so as completely to include them ; this is especially the case in some forms, which,
from tjicir peculiar mode of growth, appear to have been adherent (ex, figs. 151, 152). The
outermost segment may develope itself into numerous irregular expansions and tubular growths,

168 FAMILY LAGENIDA.

known from their appearance as " stag-horn processes " (ex, fig. 1 50) ; and these seem to be
homologous with the lobate extensions occasionally met with in " wildly-growing " Glohige-
rinee (^294), and still more remarkably in Carpenieria (^ 308). Although it is probable that
these processes are generally closed, as is surmised by Professor Williamson (ex, p. 72), yet
from the absence of any proper aperture to the segment from which they proceed, and from
their special grouping about the spot at which the aperture should be, it seems likely that
some of them are normally open at their extremities, and give exit to pseudopodial extensions.
Such " wildly-growing" specimens are probably always parasitic. — Although we have spoken
of the arrangement of the segments as normally biserial, yet they are sometimes so loosely
piled together, that three or more of them would be brought into view by a transverse
section.

262. The form of the aperture, except in the cases in which the last segment takes on the
" wild " growth just described, is usually extremely characteristic ; being circular, with a
plicated margin, so as to present a regular!}' radiating form. Sometimes the centre of the
aperture is filled up by a plug of calcareous matter (as occasionally happens in Nodosamia),
so that the stoloniferous processes must pass out through a set of radiating fissures. We
seldom find the aperture situated at the extremity of a prolonged «'/osolenian neck ; but the
earlier chambers of the most transparent forms ma)' not unfrequently be seen to be furnished
with an ra/osolenian neck; and in the later chambers, whose apertures are not prolonged in
either direction, it is generally to be observed that the plica extend as far inwards as they do
outwards. It is a very curious fact that when an outer " wild-growing" segment extends itself
over the whole of the preceding series, its cavity communicates, not merely by the usual
radiated aperture with the antepenultimate chamber, but also by a double row of openings with
all the chambers which it overlaps. It is difficult to suppose that these openings existed
anteriorly to the overgrowth ; and we can scarcely account for their presence in any other
way, than that they have been formed de novo by absorption. — The appearance of the shell in
the younger specimens is peculiarly glassy ; the walls of the chambers being thin, and the
pores which traverse their vitreous substance not being so closely set as to render it opaque.
And it is a distinguishing characteristic of this type, that its surface-character is but little
modified by that exogenous deposit, which gives such marked features to the e.xterior of Lagena,
Nodosarince, and Uvic/erina. The shell may be simply thickened, so as to became opaque ;
or it may be rendered scabrous by minute granules, and these may either run together into
fine parallel short longitudinal riblets, or they may enlarge into beads; or they may be
prolonged into aciculi, which may render the surface bristly ; — but all these kinds of
surface-ornament are met with far more strongly marked in the other genera of the
family Lagenida.

2(33. Affinities. — From the preceding description it would seem obvious that the true
affinity of Tolijmorpliina is on the one hand to the uniserial Nodosarina, and on the other
to the triserial TJvigerina. But it has a strong relation of analogy to Texfularia, the mode of
growth being essentially isomorphic in these two types; so that if we were to place our
chief reliance on that character, these two genera would have to be brought into close
approximation. For reasons already assigned, however, we consider the plan of increase

GENUS UVIGERINA. 109

of the aggregation of segments to be quite subordinate in essential importance to those cha-
racters which appertain to each segment in detail; such as, in this instance, the strongly
marked peculiarity of the aperture, and the sui-face-ornamentation, by both of which tlie real
affinities of PuJymorph'ma are shown to be with the group of genera of which we have taken
Lagena as the type.

263. Geoyrapldcal Distrilmtion — This genus shows itself under some or others of its
protean forms on nearly all the coasts wliich have been yet explored, alike in arctic, tempe-
rate, and equatorial seas. It does not often present itself in the deepest dredgings or sound-
ings, but is most common in sl)ore-sands and in dredgings from shallow waters.

264. Geolof/ical Distrih/iHo/i. — The earliest appearance yet recognised of Polijinorplnna
is in the Upper Trias. It is common in the Chalk-marl, in which several of its varieties
have been met with ; in the Chalk itself it occurs more rarely. It is extremely plentiful in
many of the Tertiary deposits, as those of Grignon, Tours, Bordeaux, Vienna, and Palermo ;
and in the Post-tertiary clays of Lincolnshire.

Genus V.— Uvigerina {Willimmon, Plate V, figs. 138—140).

265. Histori/. — With the exception of Soldani, who figured certain fossil forms of this
genus (ci) under the name of Polijmorpliina plneifornm, no systematist appears to have
noticed it previously to the characterisation of the genus by D'Orbigny (lxix) in 1825.
The name which he gave to this type appropriately indicates the resemblance of some of its
forms to a bunch of grapes.

2G6. External diameters and. Internal Structure. — The essential character of this type
consists in the triserial arrangement of its lagcniform chambers, which are disposed some-
what irregularly around an elongated axis, so as to form a spire having the proportions of
that of a Mitra. The aperture (ex, figs. 13S, 139) is a distinct round passage, with an
everted lip, generally set upon a tube more or less prolonged outwards, and sometimes
faintly toothed. When the tubular mouth is much elongated, and the chambers are globular
and distinct, the entire shell presents a well-marked racemose shape ; but in other forms
the surfaces of the segments arc flattened against each other and are also compressed
externally, so that the transverse section of the sliell becomes triangular. The triserial
arrangement, however, is not always maintained ; for in certain elongated forms of feeble
growth we find the later chambers loosely set on, and approaching a biserial or even a uniserial
arrangement ; such forms are figured by Soldani, and present themselves also in J'lngvrince at
present existing in the Mediterranean. There are even cases in which the triserial mode of
growth seems altogether wanting, and the biserial almost obsolete ; Mcs.srs. Parker and
Rupert Jones having specimens from shell-beds in the tropical and sul)-tropical parts of the
Indian Ocean which might be easily mistaken for Nodosari/ia, but whose Uvigerine character
is marked by the short, wide, strongly labiate aperture. It seems to have been a specimen
of the biserial type, that was figured by D'Orbigny (lxxiit) under the name of SayrUui

170 FAMILY LAGENIDA.

pulchella ; and other connecting links are met wdth. In large, well-developed individuals,
whether of typical or of dimorphous growth, the surface of the segments is generally marked
by elevated costa? running parallel to the axis of the shell (ex, fig. 138) ; but in place of
these we not unfrequently find the surface rendered hispid by prickles, especially in speci-
mens brought from great depths. In these forms of exogenous deposit there is a manifest
parallelism to Lagena and Nodosarina. In specimens of more feeble growth, however, the
ribbing becomes obsolete on the newer chambers ; and in some of the dimorphous forms it
is scarcely perceptible even on the earliest.

267. Affinities. — On the principles of classification here adopted, the nearest relation-
ships of JJvigerina are obviously to Polijmorplnna and Nodosarina. We shall hereafter find,
when we come to speak of Texfularia, that the dimorphism of Uvic/erina is very strikingly
paralleled in that type, as it is also in Valvuliiia (■] 221); but the relation thus indicated
is one of analogy or isomorphism, not of aflinity.

268. Geoi/rapltical Bislribidion. — The home of this type seems to be in warm seas, at
depths of from 100 to 300 fathoms ; it ranges, however, in regard to depth both upwards
and downwards, and in regard to latitude towards both polar and equatorial regions, being
found in shore-sands from all quarters of the globe, and also in deep-sea dredgings and
soundings.

269. Geolofjical Distribution. — ^This genus has not been recognised in any deposit older
than the Middle Tertiary period ; but it thenceforward presents itself abundantly in various
localities.

CHAPTER IX.

OF THE FAMILY GLOBIGERINIDA.

270, Under the general designation Globigerinida we bring together, for the reasons
already stated, all those hyaline or vitreous Foraminifera which have their shell-substance
coarsely perforated for the exit of pseudopodia, so as to resemble that of Globifferina ; a cha-
racter by which they are differentiated from the Lagenida on the one hand, and from the
NuMMULiNiDA ou the other. They are further differentiated from the former of these families
by the form and character of their aperture ; for although there are instances in which the
chambers communicate with each other, and the last chamber with the exterior, by circular
pores, yet this is only in aberrant forms of the group ; and the typical aperture is a crescent,
which may either be contracted to a narrow fissure, or which may open-out so as to have
the proportions of a gateway. There is not a like difference in the form of the aperture
between Glodi^erinida and Numinulinida ; but generally speaking, it is of much larger size, so
as to permit a much freer communication between the segments of the body in the former
group than in the latter.

271. The series of foi^ms whose agreement in these fundamental characters may be
considered as justifying their association in the same family, presents varieties of configura-
tion, dependent upon differences in their plan of growth, which are even greater than those
we have encountered in the preceding case ; and widely separated places have accord-
ingly been assigned to them by those Systematists who adopted " plan of growth" as the
basis of their arrangements. Thus, in the classification of D'Orbigny, our genera would be
distributed as follows :

Order I. — MoNosTisGUEs. Orbulina, Ovulites, Spirillina.

Order II. — Cyclostegues. Tinoporus (Orbitohna, L'Orb.), Patellina.

Order IV.^ — H^licostegues. Globigerina, Carpenteria, PuUenia (part of Nonionina,
D'Orb.), Bulimina, Chrysalidina, Rotalina (including Rosalina, Pla-
norbulina, Anomalina, Calcarina, and part of Asterigerina, B'Orh.)

Order V. — Entomostegues. Cassidulina.

Order VI. — Enallostbgues. Textularina, Cuneolina.

Order VII. — AGATHiSTtiGUES. Sphseroidina.

172 FAMILY GLOBIGERINIDA.

A nearer approximation to what we consider the true view of their affinities is presented
by the system of Prof. Schultze (xcvii) ; who separates Orbulina and Spirillina {Cormispira,
Sch.) from his other Monothalamia, and brings together Rolalida, Teaiilarida, and Cassi-
(Miirida, with Vvcllida, as sub-families of his family Turbinoida, which holds very much
the same relation to his family Nautiloida, that our family Globigerinida holds to our
NuMMULiNiDA. If Prof. Schultzc had expunged his UveJIida from the former, and his
CristeUarida from the latter, and had united these with his family Nodosarida, his general
arrangement would have differed in this part but little from ours, except in the complete
line of demarcation which he draws between the monothalamous and the polythalamous
forms characterised by essentially' the same type of structure. On one point, however,
we are altogether at variance with him ; namely, the value he assigns to his Family Acer-
VULINIDA, which consists of what is in our view but an aberrant form of the Rotaline type,
that is distinguished by its "wild" or acervuline growth, the segments being piled one upon
another without any definite plan.

272. Taken as a whole, our family Globigerinida may be considered as holding an
intermediate rank between our Lagenida and our Nummulinida. In common with the
former, it has its root (so to speak) among the Monothalamia, from which it extends itself
upwards in various directions, like a tree whose trunk early subdivides into branches. But
whilst the development of the Lagenida is checked at a low grade, so that even their most
elevated forms present very little real advance upon the most simple, that of the Globige-
RiNiD.i goes on so much further, that we find in the highest types of this family a com-
plication of structure scarcely inferior to that which characterises the highest Nummulinida.
When we come, however, to consider the relations of the principal generic types of this
family, both among themselves and to other groups, we find that they cannot be
expressed by any linear arrangement ; and the only practicable method, therefore, is to
follow that which seems to be the line of most intimate relationship so far as it may lead,
and then, returning to the original starting-point, to take a fresh departure in some other
direction.

273. There can be no hesitation in regarding the monothalamous forms as being those
which present the fundamental or essential " idea" of this group under its simplest aspect :
and yet these are differentiated from each other by very marked characters ; — Orbulina being
often destitute of any pi-incipal aperture, but having numerous secondary apertures of larger
size than the ordinary pores ; Oviditcs, on the contrary, presenting an aperture at each end
of its egg-shaped chamber ; whilst in Spirillina the single chamber is elongated into a nearly
cylindrical tube, coiled upon itself into a spire, which, closed at its central extremity, is freely
open at its peripheral. In the two former, as in the Gromida and in Layena, the act of
gemmation consists in the production of a segment, which (except in certain cases of mon-
strosity) detaches itself from the original body and forms its own separate investment ; but
in the latter it consists in a simple elongation of the sarcode-body and continuous extension
of the sliell, without any appearance of segmentation. It is obvious that from either of these
monothalamous types an ordinary polythalam may be derived ; for, on the one hand, the
segments successively budded off from a globular Orbulina may remain in continuity with

FAMILY GLOBIGERINIDA. 173

it and with each other, producing either a spiral or some other figure, according to their
direction of increase ; whilst, on the other, the continuous tube of a Sjyirillina may contract
itself at intervals so as to form a succession of chambers, just as we have seen a Cortmspira
convert itself into a spiroloculine iI////o/rt (If 104). Now we find among the lowest of the
Polythalamous forms exactly such as might be the resultants of each of these modifications ;
for in Ghhigerinci we have a spiral aggregation of segments which are really disconnected
from each other, although united by mutual adhesion ; whilst in certain vermiculate forms
of the Rotalinc type we shall be very strongly reminded of what a SpirilHiia would be if
scgmentally divided at intervals by partial constrictions.

274. In immediate structural relation to Globir/eriiw, but diverging from it in plan of
growth, we find the two small genera FuUenia and Spha-roidlna, of which the former, in the
finely poi'ous texture of its shell, and in the equilateral disposition of its spire, conducts us
towards the simplest " nonionine " forms of Polijstomella, a member of the family Nummu-
LiNiDA ; whilst the latter, though essentially " globigerine " in the character of its segments,
has them applied one to another in a manner that reminds us of some forms of the Milioline
type, to which it also bears a further curious resemblance in having its aperture furnished
with a kind of " valve. "^ — The Globigerine type evolves itself, however, without any departure
from its essential character, into a much more complex form, Carpenteria ; which, on the one
hand, presents us with a singular feature of approximation to Sponges, whilst, on the other,
it exhibits, in the duplication of its septal laminae, and in the presence of a canal-system, an
elevation of type which is not a little remarkable as based on a foundation so humble.

275. Although we might very naturally pass from Ghhigerina to the Rotaline series,
yet it seems desirable, in the first place, to notice the Texttilarine ; because, although the
lower types of the two may be considered as on the same grade of development, the highest
types of the former rise far above those of the latter. The genera of which the Textularine
series is composed, are characterised by the alternating arrangement of their chambers upon
an elongated axis ; the successive chambers freely communicating with one another by
(usually) crescentic apertures ; but each being so applied to the preceding that the septum is
single, so that there are neither intraseptal spaces, intermediate skeleton, nor canal-system.
This group thus represents in its own series both the Uvigerine type of the vitreous-shelled
family Lagenida, and the Valvuline of the arenaceous Lituolida ; and its relationship to
the latter seems to be even more intimate than to the former ; since both in Te.vtidaria and in
Biillmina it frequently happens that the proper substance of the shell is replaced to a great
extent by an aggregation of sandy particles, in the midst of which, however, the pseudopodial
pores are still traceable. It is unquestionably in these aberrant modifications of their re-
spective series, that the great primary groups of Perforate and Imperforate Foraminifera show
the most intimate relationship ; the iijpivul forms of those groups, even when most resembling
one another in external configuration, being most completely differentiated in essential
characters. — In tlic ordinary Textularia the alternation of the chambers is essentially biserial;
but in some of its subgeneric modifications it is triserial, whilst, on the other hand, it may
become uniscrial. In Bidimuia, again, the chambers are disposed, without any definite
number, in a spire which strongly resembles that of a Bidiimts ; but in some of its subgeneric

174 FAMILY GLOBIGERINIDA.

modifications it becomes biserial. These two generic types differ essentially, however, like
TJvigprina and FoJymorphlna, in the setting-on of the chambers, and in the form of the
aperture. In Chri/mUdlna and CuneoJina, whose plan of growth is Textularine, the large,
single aperture is replaced by a multiplication of pores. And in Cunsidtdma, of which the
aperture is Bulimine, and the chambers alternate biserially, the elongated axis is itself coiled
into a spiral, affording the only real example of that complex plan of growth on which
D'Orbigny founded his order Enallostegues.* As the Nodosarine type culminates in
CristeJlaria, so may we consider the Textularine as culminating in Cussidullna ; and the
latter of these genera, like the former, is altogether destitute of those peculiar features which
characterise what may be unmistakeably recognised as the most elevated forms of the
family Glohigerinida.

276. To such forms we can only ascend by returning again to those simpler derivations
from the Globigerine and SpiriUine types, which constitute the lowest forms of the Bofaline
series : this consists of a group of genera whose typical character consists in the arrange-
ment of the chambers in a turbinoid spiral, and in their communication with each other by
an aperture (usually more or less crescentic in form) situated at its inner and lower
margin. Now the simplest forms of this Rotaline spire present a close parallel to the
Textularine series in the manner in which each segment applies itself to the preceding ; but
the same type may be traced upwards, through successive grades of development, until we
arrive, in the highest form of Rotalia Beccarii, at a condition scarcely inferior to that of Ojier-
culina in I'egard to the differentiation and duplication of the septal laminae, the system of intra-
septal canals, and the supplemental skeleton. In the genus Calcarina we find an exogenous
develoj^ment of the supplemental skeleton, and of the portion of the canal-system provided for
its nutrition, which is unparalleled elsewhere; but it is not a little singular that this modification
is related rather to the higher than to the lower forms of the Rotaline series ; the septal
laminae being for the most part single, so that the intraseptal portion of the canal-system is
but little developed. It is further worthy of note in this genus, that the narrow, crescentic,
apertural slit is divided by cross-bars into separate circular pores.

277. The greatest departure from the normal development of the Rotaline type is shown
in the entire cessation of the regular plan of increase, observable in all but the earliest stage
of growth of certain forms, which, in the structure of their individual segments, are entirely
conformable to the Globigerine type. The essentially Rotaline character of these organisms
is marked by the tui-binoid spiral in which they usually commence ; whilst the forms they pre-
sent in their fully developed condition are so far from suggesting their real relationship, as to
seem in many instances to claim for them a completely separate place in the series. By the

* The genera Asterigcrina and Heterostegina, whicli were placed by D'Orbigny in this order,
have no claim whatever to be thus differentiated from their congeners ; and although in Amphistegina
there is often a want of equality between the alar extensions of the chambers on the two lateral sur-
faces, with a separation of the umbilical extremities of those extensions into secondary chamberlets,
there is no really biserial alteration.

FAMILY GLOBIGERINIDA.

175

flattening out of a Rotaline spire, and the cyclical or concentric growth of chambers from its
margin, it takes on the form known as the Planorhulina ; and this may undergo a further
modification, on the one hand, by that irregular heaping up of chambers one upon another
which constitutes the " acervuline" mode of growtli ; on the other, by the interposition of a
large amount of soUd shell-substance between and upon the chambers. This acervuline
mode of growth is carried still further in the genus Tinoporus {Orbitolinu, D'Orb.), some forms
of which also present an extraordinary development of the exogenous portion of the inter-
mediate skeleton, strongly resembling in external aspect that of Cat carina, and accompanied,
like it, by a corresponding development of the peripheral part of the canal-system. And it
is a most interesting indication of the mutual relationship of these two types, notwithstanding
the complete dissimilarity of their modes of growth in their adult condition, that in their
early Rotaline state they are absolutely undistinguishable from each other. In Tinoporm,
moreover, as in CaJcarina, the setting on of the chambers follows the plan of that of the
lower Rotalines, not that of the higher. We are probably to rank the genus Patellina, whose
plan of growth tends early to become cyclical, as a still more aberrant member of the Rotaline
series. Finally, in PoJi/frema the growth becomes so " wild " that the aggregations of chambers
present a zoophytic form ; and as their origin in a Rotaline spire cannot be demonstrated with
certainty, their relationship to this type is established only by their conformity in structure
and mode of growth to the acervuline portions of Tinojiorus ; which conformity will be shown
to be so complete as to leave no room whatever for doubt as to their true nature.

The following arrangement of the genera may help towards the understanding of the
principal relationships that have been indicated among them ; but no sucli arrangement can
give more than a partial view of those relationships : —

FAMILY GLOBIGERINIDA.
Ovn/ttc's OrbuVum ,

Textularin^

BuUmina
Virgulina
Boliviua

Cassidulina
Ehrenbergina

Tcdiularia
Bigeueriiia
Gaudryina
Verneuilina
Grammostomum

CuneoUna

ChrysaUdlna

GlOBIGERINvE

Globif/erina
SpJieBroicUna Pullenia

Carpenieria

SpirilHna

Rotaline

Biscorbina

Planorbtiliiia
Truncatulina
Planulin.i
Anomalina

P iilvinulina

Rofalia

Cymbalopora
Calcarina
I'inoporu.s
Pat el Una
Polyircma

176 FAMILY GLOBIGERINIDA.

Genus I.— Orbulina (Plate XII, fig. 8).

278. History. — The little spherical bodies to which the appropriate name Orhulina was
first given by D'Orbigny in 1839 (xcii), had been described and figured by Soldani (ci)
under the names Sphcenda pdma and S. Mspida ; but they do not seem to have received any
attention from intervening authors. Subsequently to its recognition by D'Orbigny, this type
has been generally adopted by systematists as a distinct genus until a recent date, when its
claim to that rank has been called in question, on grounds which will be presently explained.
Not being as yet satisfied of the invalidity of that claim, but not, on the other hand, feeling
able to affirm that the objections to it are altogether groundless, I have thought it best
to retain the genus provisionally ; especially since I find that my friends Messrs. Parker and
Rupert Jones are in accordance with me as to the propriety of this course.

279. Externcd Characters and Internal Hlmcliire. — The shell of Orhdina is usually an
almost perfect sphere, varying in diameter from l-35th to l-200th of an inch. Its surface
is usually roughened by minute tubercles, presenting an appearance which is described by
Professor Williamson (ex, p. 2) as " arenaceous ;" but I am satisfied that its substance is not
made up of any such aggregation of foreign particles as constitutes the material of the truly
" arenaceous'' shells ; whilst, on the other hand, it is only in the earlier stage of its formation
that it has the hyaline transparency characteristic of the truly •' vitrer us" shells. The shell
is pierced (Plate XII, fig. 8) with a number of large pores, the average diameter of which is
about l-1500th of an inch ; their distance from each other varies considerably, but is seldom less
than about l-7oOth of an inch. Between these there are very numerous minute pores, not above
l-10,000th of a inch in diameter, and closely set together, so as to be pretty uniformly distri-
buted. In the large majority of specimens these constitute the only apertures in the globular
shell; but we frequently meet with one of larger size, normally round, but sometimes
irreo-ular, its diameter averaging l-500th of an inch. I am much disposed, however, to
question how far this can rightly be regarded as comparable to the aperture of ordinary
Foraminifera ; since, on the one hand, it is often absent ;'•' whilst, on the other, when it exists^
it is only one among the very numerous large pores by which the shell is fenestrated, distin-
o-uished from the rest only by its pre-eminent size. I believe the truth to be that the sarcode-
body puts forth its prolongations indifferently from any or all the pores ; and that, when this
organism multiplies itself by the formation of detached gemmae, these are budded off from the
o-elatinous mass which the coalescence of these prolongations will form on the exterior of the

* It is remarked by M. D'Orbigny (lxxiii, p. 31) that as the aperture is frequently invisible,
not showing itself in above one-sixth of the freshest specimens, the animal may possibly possess the
power of closing it. Prof. Williamson (ex) confirms D'Orbigny's statement of the infrequency of
the aperture ; but thinks that " its frequent closure is more probably due to the inspissated animal
matter of its internal cavity." My own observations satisfy me that the existence of a single
aperture of any considerable size is the exception rather than the rule.

GENUS ORBULINA. 177

shell. In the OrhulincE of comparatively shallow waters, the shell seems to retain through life
its hyaline aspect, not appearing to receive any augmentation in thickness subsequently to its
first formation. In those brought up from deeper waters, on the other hand, we commonly
find the original hyaline shell to be encrusted by an exogenous deposit of coarser texture and
of a reddish hue, having a peculiar sculptured surface (fig. 8, a) which reminds the observer
of that of some of the hispid pollen-grains.

280. Not unfrequently this exogenous deposit, instead of closely adhering to the surface
of the shell which it encloses, forms a distinct sphere that is exactly fitted to it without being
continuous with it, — a circumstance which seems first to have been pointed out by Mr.
Pourtales,* who supposed that the inner shell is the more recent or younger, and that the outer
one is the older and is destined to be cast off. Of this, however, I see no evidence whatever;
whilst, on the other hand, not only is it found that a more delicate hyaline layer always
exists within the outer less transparent coat (as may be easily shown by removing the latter by
the careful application of dilute acid), but this outer layer is occasionally so loosely applied to
the interior, that a considerable space remains between them over a larger or smaller portion
of the surface of the sphere, so that the outer layer forms a protuberance enclosing an
additional chamber, which is sometimes of small proportionate size, but sometimes has nearly
the dimensions of the original sphere. (This seems to be the form described by D'Orbigny,
Lxxiii, as Globif/erina bilobnta.) In one specimen in my possession, the sphere bears two such
protuberances, both of them small. It is particularly worthy of note that the secondary cavity
thus formed has no other communication with the single cavity of the original sphere, than
that which is afforded by the ordinary pores of the shell-wall ; there being no apertural
passage between the two. Hence, although such an excrescence may in some sense be
regarded as a sort of attempt at the formation of a new chamber, the rarity of its presence
seems to forbid the idea that its formation is anything but abnormal. In fact the perfection
of the spherical form in all but such extraordinary specimens of OrbuUna is extremely
remarkable ; there being not the slightest indication on any part of their surface of ever
having been attached by adhesion to any other organism, still less of ever having been con-
tinuous with any other fabric and having been separated from it by fracture.

281. It is affirmed, however, by Mr. Pourtales (loc cit.), that in nearly one half of the
Orbulina which he examined among the large number of well-preserved specimens obtained
from the bottom beneath the Gulf Stream by the U.S. Coast Survey, he found "young
Globigerinm more or less developed, and attached to the inside of the OrbuUna by numerous
very slender spicules. Only one Globigerina is developed in an Orhulina, whose cavity it
gradually fills up, and whose shell it finally bursts to make its escape. At that time the
Globigerina has already nearly attained its full size ; and I have counted as many as sixteen
cells in a specimen having yet room for several more before filUng up the parent Orbuhna."
It is not rare, continues the same observer, to find Orbulince with the double shells just
described containing young Globigerina. Further, it is stated by Prof. Schultze (xcix), that
Dr. August Krohn has seen exactly the same thing in living Orbulince captured with the

* 'Silliman's Journal,' July, 1858, p. 96; and 'Annals of Natural History,' September,
1858, p. 236.

23

i78 FAMILY GLOBIGERINIDA..

tow-net (?) at. the surface of the sea near Madeira ; and Prof Schultze thinks it the most pro-
bable supposition that the last chamber of the Ghhigerina, when it has attained a certain age
and size, separates hke the proglottis of a Tania, and, after living in a free state for a longer
or shorter period, effects the reproduction. Now I have very carefully laid open by the
application of dilute acid the spheres of a considerable number of Orhulines ; and I have not
met with a Ghhigerina in the interior of a single one. Without wishing to affirm that my
negative observation necessarily invalidates the statements just quoted (since it is quite
possible that, supposing OrhuIincB to be generative segments of Globigerina, the contents of
my specimens may not have been sufficiently advanced towards maturity at the time they
were gathered, to be recognisable in the dry state), it derives support from the following facts:
— 1. The marked difference in size between the OrbuJince and the Glohigerince of the same
" gathering," the diameter of the former averaging l-40th of an inch, and the smallest being
i-85th, whilst the diameter of the largest chamber in the latter averages 1-lOOth of an inch,
seldom exceeding 1 -80th. — 2. The perfect sphericity of Orhulina ; whilst the larger chambers
of ff/o^2j'm«a almost invariably depart considerably from the spherical form.^ — 3. The entire
absence of any indication whatever that Orhulina have been attached to, or continuous with, any
other organisms. — 4. The constancy of a large aperture in the segments of Globigcrina ,• whilst
it is deficient in so great a proportion of Orhulines that its presence may be considered as
exceptional. — 5. The absence in Ghhigerina of the larger pores by which the shell-wall of
Orhulina is so abundantly pierced. — Taken in mutual connection, therefore, the facts I have
adduced at present seem to me sufficient to justify the retention of Orhulina as a substantive
genus ; the only fact that occurs to me in support of its asserted relationship to Ghhigerina
being the generality of their association. Even this, however, does not appear to be uni-
versal ; for although at the present epoch the two forms generally occur together, this associa-
tion is by no means constant ; and, moreover, Ghhigerina presents itself much earlier in
Geological time than Orhulina.

282. Affinities.— \i we consider Orhulina to be entitled to rank as a substantive genus,
we cannot hesitate in regarding it as the simplest conceivable form of the hyaline Forami-
nifera ; since it corresponds with that globular primordial segment, in which, as a rule, even
the most complex among them has its origin. In this way it may be said to be related to all
the higher forms ; but its nearest affinities are of course, on the one hand, to the mono-
thalamous types Ovidites, Lagena, and Spirillina ; and, on the other, to Ghhigerina, as being
that one of the polythalamous forms which most resembles an aggregation of monothalams.

283. Geographical and Geological Distribution. — This genus, as Prof. Williamson remarks,
is a true cosmopolite ; being an inhabitant of all seas through a great range of depths. It
seldom presents itself, however, in shore-sands ; as it does not frequent shallow waters. On
bottoms of fine sand or mud, at depths of from 30 to 2350 fathoms, OrhulincB have been
found in abundance in every maritime region. Such a range in space, according to general
experience, would indicate a corresponding range in time ; but the rule does not seem to
hold good in this instance, for Orhulina have not been detected in any formation earlier
than the Miocene Tertiaries. It is especially abundant in the Vienna and Sub-Apennine
deposits.

GENUS OVULITES. 179

Genus II.— Ovulites (Plate XII, figs. 9, 10).

284. History. — The name Oveoliks was applied by Lamarck in 1801 (lvii) to a minute
fossil, abundant in the " Calcaire grossier," which has very much the aspect of a bird's gge
in miniature ; and this name was subsequently (lix) altered by him to Ovulites. Under this
latter designation the genus has been adopted by various systematists, most of whom, how-
ever, have seemed uncertain as to its true place, which has generally been supposed to be
among Zoophytes. And even D'Orbigny has included it among Foraminifera only in his
most recent systematic publication (lxxiv) ; ranking Bactylopora (^ 187) in close proximity
to it!

285. External Characters. — This beautiful little fossil type is the largest of the mono-
thalamous Foraminifera ; its one segment, which is usually about the size of a mustard seed,
equalling in bulk the entire polythalamous shells of ordinary 3fitioIa, Motalia, &c. The
typical form of the shell is ovate, with an aperture at each end, so as to give it a striking
resemblance to a " blown" bird's egg (Plate XII, fig. 9) ; while the pearly aspect which it
often presents caused Lamarck to confer upon it the specific name maryaritula. Various
aberrant forms, however, present themselves ; most of them being the result of elongation
with or without occasional constriction. Thus a moderate degree of elongation with con-
strictions at intervals (a sort of foreshadowing of division into chambers) gives to some
specimens the aspect of sausages ; whilst a greater degree of elongation will produce a long
straight tube (the 0. elonyuta of Lamarck) ; and this tube may be clavate at one or both ends,
so as to resemble a drumstick or a life-preserver (fig. 10). In every case there is a large round
aperture at each end ; and this is the most distinctive character of the genus. The cavity is
simple and undivided, though sometimes narrowed by the constrictions which show them-
selves externally. The shell -wall is perforated by large sparse pores ; and these very com-
monly open on the surface into minute superficial depressions, which, in some of the
elongated forms, are so regularly arranged as to give rise to a delicate hexagonal areolation,
having a pore in the centre of each areola (fig. 9, «), — the superficial resemblance thus pre-
sented to Bactylopora (^ 124) having probably infiuenced D'Orbigny in his approximation of
that most complex type to the simple Ovulites. Specimens that have escaped molecular
change present the clear, smooth, glassy appearance characteristic of the hyaline Fora-
minifera.

286. Affinities.— 'YXiQ close relationship between Ovulites and Orhdina is sufficiently
obvious ; as is also that between Ovulites and Layena, especially through the distomatous
varieties of the latter (f 237), — the coarser texture of the shell, however, and the absence of
anything like an everted lip with radiating notches, being marked features of difference. The
elongated forms may be considered as related on the one hand to Spiriltina, and on the other
to these vermiculate forms of the Rotaline PulvinuUna which have wildly growing, attenuated,
and prolonged chambers.

180 FAMILY GLOBIGERINIDA.

287. Geological Distribution. — This genus, so far as is at present known, was limited to
the earlier portion of the Tertiary period ; making its first appearance in the Eocene deposits
of Grignon and Hauteville, in which it is extremely abundant; and lingering, under its
attenuated forms, in the Miocene of St. Domingo. In no deposits of subsequent date has
it been recognised.

Gems III.— Spirillina (Wilhamson, Figs. 202, 204).

288. History. — Through the marked isomorphism between this genus and Cornuspira
(^ 82), it cannot be affirmed with confidence to which type we are to refer the figures and descrip-
tions of minute spiral monothalamous shells given by Soldani and after him by other authors,
who did not clearly distinguish between such as are imperforate and porcellanous, and such as
are perforated and hyaline. It is probable, however, that while the " albocalcarefe" of Soldani
^CI) belong to the former, his " margaritiferae," which he describes as iridescent, belong to
the type now before us. The generic designation Spirillina was originally conferred upon
the perforated hyahne spiral monothalams by Prof. Ehrenberg (xl a) ; but it has not
gained general acceptance. It was set aside by Prof Schultze (xcvii) for the term Cornu-
spira ; but this name was in its turn set aside by Prof Williamson (ex) in favour of
Ehrenberg's name, which, however, he applied to the porcellanous and arenaceous as well as
to Ihe hyaline forms. For the reasons already given, we think it better to appropriate Schultze's
generic name as the designation of the porcellanous type (^ 82), to adopt the new name
Trochammina for the arenaceous (^ 206), and to retain Ehrenberg's name for the type on which
he originally bestowed it, notwithstanding that he has since expressed his belief (' Monatsber.
der Akad. der Wiss. zu Berlin,' 1857, 1858) that this type really belongs not to the Foramini-

fera but to the Polycijsti na. (See also xcix.) Examples of this type have been figured
by Reuss (lxxxvi) as low forms of Operculina.

289. External Characters and Internal Structure. — The shell of Spirillina is a simple
undivided cylindriform tube of hyaline substance, usually perforated with rather large
foramina, and coiled spirally on a horizontal plane; the successive coils do not increase rapidly
in size, and show but little tendency to flatten themselves out, retaining for the most part
their circular section (ex, fig. 202). The principal variety presented by this type results from
the modification imparted to its surface by exogenous deposit ; for specimens not unfrequently
occur, in which all save the last-formed portion is studded with pearly tubercles, while the
foramina are so small and inconspicuous as not to be seen without close examination (ex, fig.
204). The diameter attained by this shell does not usually exceed l-50th of an inch.

290. Affinities. — According to the view on which our classification of Foraminifera is leased,
there is no real affinity between Spirillina and either Cor)iuspira or Troclinmmina, notwith-
standing the precise resemblance in the forms of their shells ; since in the first of these types
the pseudopodia may be put forth from any part of the sarcode-body, whilst in the two latter
they can only be extended from the moutli of the spire. The real affinity of Spirillina is with

GENUS GLOBIGERINA. 181

the monothalamous forms of the Globigerine family ; and it cannot fail to be obvious to any one
who accords with us in regarding the external form of such protean creatures as of little ac-
count, that if one of the chambers of a Ghhigvrina were to elongate itself indefinitel)^ instead
of closing itself in and budding off another segment, we should have iSplrillina. As already
remarked (^ 62), this genus, like Cornuspira and Trodiammina, though actually monothalamous,
is " potentially " polythalamous, in virtue of its power of unlimited extension.

291. Geographical and Geological Disirihuiion.- — This genus is very generally diffused at
the present time, and seems ordinarily to inhabit shallow waters, being found rather in shore-
sands than in deep-sea dredgings. It makes its first appearance in the Calcaire Grossier ;
and is met with in various Tertiary deposits.

SUB-FAMILY GLOBIGERINA.
Germs IV.— Globigerina (Williamson, Figs. 116—118; and Plate XII, fig. 11).

292. Histori/. — The only distinct notice of the shells belonging to this type, that has
been detected in the writings of the earlier authors who have treated of Foraminifera, occurs
in the great work of Soldani (ci) ; who has figured and described the form now known as
Globigerina lulloicles under the names Polgmorphia tuberosa and P. glohulifera. The genus
was first characterised by D'Orbigny (lxix) in his earliest classification of Foraminifera ;
and it has been adopted by all subsequent systematists.

293. External Characters and Internal Strttcture. — The name given by D'Orbigny to this
type is very expressive of the globose aspect which its segments generally present. In its
typical form, the G. lulloides of D'Orbign}', the shell consists of a series of eight or ten such
segments, increasing rapidly and pretty regularly in diameter from about 1-2000 to l-80th
of an inch, and arranged in a turbinoid spire, forming from two to three convolutions. The
segments are always somewhat flattened against one another at their planes of junction ;
and sometimes this flattening extends over a pretty large surface. The entire series of
segments shows itself on the upper side ; but on the lower side only the segments forming
the latest convolution are prominent, these being usually four in number, and being arranged
symmetrically around a deep umljilical depression or " vestibule," the bottom of which is
formed by the segments of the earlier convolution. Into this vestibule each segment opens
by a large crescentic orifice, the several chambers having no direct communication with
each other. The entire shell of the ordinary type may attain a diameter of aljout l-30th
of an inch, but it is usually much smaller. — This typical form, however, is subject to very
considerable modifications. Thus in the G. helicina the later chambers lose their spheroidal
form, and become flat, outspread, and loosely lobulate or palmate (Plate XII, fig. 11) ; thus
exhibiting a manifest tendency to that remarkable departure from the ordinary plan of
growth, which reaches its full development in Carpenferia (^ 308). On the other hand we
observe in certain Globigerince (as the G. hirsidu) a decided tendency towards the symme-

182 FAMILY GLOBIGERINIDA.

trical plan of growth, so as to give them somewhat of a nautiloid aspect, their essentially
globigerine character, however, being still marked by the distinctness of the apertures of the
several segments : and other forms are flat, with raised edges and elevated septal bands.

294. The newly formed segments of Ghhigerina have their chamber-walls composed of
a hyaline shell-substance, which is perforated by minute tubuli of uniform size arranged at
pretty regular distances. The diameter of these tubuli varies in different specimens from
about l-10,000th to l-5000th of an inch; but we nowhere meet with any pores at all
approaching in size to the large pores of Orbulina, nor do we find pores of two very different
dimensions coexisting in the same individual. In the Globigerina of shallow waters, the walls
of the chambers retain through life their original thinness and transparence ; but in those
of deeper seas they are generally thickened by exogenous deposit, the surface of which is
raised sometimes into minute tubercles, and sometimes into ridges, in the depressions between
which are seen the orifices of the pores ; and specimens are frequently met with, in which
the ridges form a regular reticulation, with the opening of one of the pores in each areola.
Sometimes the ridges bear acicular prolongations ; as is well seen in some of the symmetrical
specimens that abound in the Red Sea, in which the needles are so long as to subdivide the
large arched aperture of the later chambers. In other instances, again, the entire ridge
surrounding each areola rises so high from the surface, as actually to form a tube that
encloses the pseudopodium in its course outwards from the pore of the chamber-wall ; this
peculiar condition has been observed in nautiloid (symmetrical) specimens from 1600 or 1700
fathoms' depth between Malta and Crete and from the deeper parts of the Red Sea.

295. Each chamber is occupied during life by a reddish-yellow segment of sarcode,
from which pseudopodia are seen to protrude ; and it seems probable that the sarcode-body
also fills the umbilical vestibule, since without some such connecting band it is difficult to
understand how the segments which occupy the separate chambers can communicate
directly with each other, or how new segments can be budded off. It has been noticed by
Dr. Wallich (civ a) that in the Ghligerino: brought up from great depths the hue of the
sarcode-body is dingy, and inclines rather to brown than to yellow ; whilst its particles are
less united into a viscid mass, and more disinclined to coalesce again after being crushed
asunder, than they are in the specimens obtained from shallower waters. Moreover, he has
in no instance seen the pseudopodia extended in deep-sea specimens ; but their surface,
when they are newly taken out of the water, is studded with little yellow-coloured masses,
closely applied to, and somewhat larger than, the apertures from which they emerge ; and
these masses are not unfrequently visible even on the surface of the dry shell!

296. Affinities. — This genus stands alone among the polythalamous Foraminifera of the
hyaline series, in having its shell composed of an aggregation of segments which are merely
connected by external adhesion, and have no internal communication w-ith each other. In
this respect it corresponds with Ladylopora and Acicularia among the porcellanous forms ;
bearing, like them, a really stronger resemblance to its monothalamous than to its polythala-
mous congeners (^ 203). If the new segments of Orbulina, instead of detachmg themselves
(as they ordinarily seem to do) previously to the formation of their investing shell, were to

GENUS GLOBIGERINA. 183

remain in continuity with that from which they are put forth (as they do in exceptional cases),
we should have the likeness of GloUgerina, differing solely in the presence of the large pores
which constitute the distinctive feature of Orbidina. Again, the wildly growing forms o)
GloUgerina obviously tend towards Carpenlerin, as will be evident when the remarkable struc-
ture of that genus shall have been explained. By its symmetrical variety, Glohigenna is showoi
to be related to those nautiloid Foraminifera which are the highest types of the hyaline series.
But its nearest relationships are to its congeners Pullenia and SpJueroidina, and to the Rota-
line genera Discorbina and Planorhnlina ; the smooth-walled compact GloUgerina (such as
have been named G. ittflata by D'Orbigny, v) presenting a close approximation to specimens
of Pidlenia obliquiloculata of Parker and Rupert Jones (a variety of the Nonionina sphmroides
of D'Orbigny) brought up from great depths ; the large, extremely thick-walled, compact
GloUgerina of the deepest waters approaching in like manner to the equally abyssal solid
Sphceroidiria ; and the moderately depressed flat-chambered forms presenting a strong
resemblance to certain modifications of the Rotaline type.

297. Geographical Distribution. — -This genus ordinarily inhabits the deeper waters of tlie
ocean, through which it is very extensively distributed, although not as universally as has
been represented. It is not common in shore-sands or in dredgings from shallow waters ; but
often presents itself in extraordinary abundance in deep-sea dredgings, and in the contents of the
scoop attached to the deep-sea sounding-apparatus. Thus Mr. Parker found it to consti-
tute 97 per cent, of the soundings brought up by Capt. Dayman from a depth of 2000 fathoms
in the Mid-Atlantic ; and Dr. Wallich (civ a) met with a like proportion in soundings taken
between Cape Farewell (Greenland) and the island of Rockall, at depths respectively of 1260
and 1607 fathoms. The surface-layer of the "ooze" seems to be formed of living shells;
whilst its principal mass consists of the exiivicB of preceding generations. It is a remarkable
fact that the occurrence of GloUgerinm in any quantity in the deep-sea deposits of the
Northern Atlantic Ocean is associated in an intimate manner M'ith the presence of the Gulf
Stream or its offshoots. Thus they abound in the soundings taken between Ireland and
Newfoundland, in those taken between the Faroe Islands and Iceland, and in those taken
midchannel between Iceland and Greenland, — diminishing, however, towards the latter
coast ; whilst from the soundings taken between Greenland and Labrador they are entirely
absent. Again, they have been found in the deep waters off Shetland more abundantly than
in the neighbourhood of any other portion of the coast of Great Britain ; and thej' a-re also
met with on the northern coast of Norway. This association appears to be wholly irrespective
of the direct drifting action of the Gulf Stream, which can scarcely extend to the profounder
depths of the ocean ; and it would rather seem to depend on the presence in it of a large
quantity of organic particles, derived from the Gulfs of Mexico and Florida, or from the
Sargasso fields, which afford nutriment to the Globigerince. The genus is also met with,
frequently in such abundance as to constitute 50 per cent, of the " ooze," in the deeper
waters of the Mediterranean and the Adriatic, in the Red Sea, and in the neighbourhood
of the Canaries, the West Indian Islands, the eastern and western coasts of South America,
St. Helena, and the Isle of France. On the other hand, in the deep sea-soundings taken
in various parts of the great " Coral Sea," Glohigerina do not seem to occur.

298. Geological Distribution. — As far as is yet known, this genus first presents itself in

184 FAMILY GLOBIGERINIDA.

the Gault, in which it is small and not abundant. It is, however, extremely abundant in the
Chalk-marl and Chalk, forming a considerable proportion of some specimens of those deposits ;
and it occurs in nearly all Tertiary beds of deep-sea origin,- — the Vienna and Sub-Apennine
Tertiaries yielding it iii greater amount than the basins of Paris and Bordeaux.

Genus V.— Pullenia (Plate XII, fig. 12).

299. Histori/.— The generic designation Pullenia is applied by Messrs. Parker and
Rupert Jones to a minute form which has been represented by M. D'Orbigny (Modeles, No.
43) under the name of Nonionina sphceroides, and has been subsequently described by him
(lxxiii) under the name of N. hdloides. It differs so widely from the ordinary Nonionina
(which we shall hereafter see to be low forms of Poli/sfomella), and presents such features of
approximation to Globigerina, as to justify its being ranked as an aberrant form of the group of
which the latter is the type ; whilst it is differentiated from all other forms at present known
by characters that are of sufficient importance to justify its being ranked as a distinct genus.
The place here assigned to it will be found to harmonise in a remarkable manner with the
peculiarity of its geographical distribution.

300. External Characters and Infernal Structure.— The shell of Tulhnia has a globose

form, the distance between its two poles being nearly or quite as great as the diameter of the

spire (Plate XII, fig. 12). It is formed of a series of segments following one another in a

symmetrical or nautiloid spiral, the number of these segments in each turn of the spire being

usually four or five; each whorl is normally invested by that which succeeds it, the chambers

of the latter being prolonged on either side to the centre of the spire ; and the last chamber

is usually large, occupying about one third of the lateral aspect of the spire. The septal plane

is a narrow crescent (fig. 12, a); and the aperture is a very elongated fissure, extending almost

from one point of that crescent to theother. The segments are in general but slightly convex,

without any considerable depressions at their junctions ; but sometimes they are turgid or

vesicular, and obliquely coiled, like the chambers of Globigerina ; and it may then happen

that they do not so far extend themselves over the preceding whorl as to conceal it, so that

the whole spire remains visible. These minute shells are extremely glassy in their texture,

and their pores are fine. They are among the smallest Polythalamia at present known ; their

diameter averaging l-50th and never exceeding l-30th of an inch.

301. Affinities. — This type is related to Globigerina in the simphcity of its structure, and
in the occasionally globigerine character of its chambers, as well as in the wideness of their
aperture ; whilst among true Globigerina there are some forms which approach it in mode of
growth. On the other hand, it is related to Nonionina in its plan of growth, and in the com-
parative fineness of its porosity.

302. Geograpliical and Geological Distribution. — The home of this genus — like that of
Globigerina, but unlike that of Nonionina — is in the deep seas, especially those of warm

GENUS SPH^ROIDINA. 185

climates ; its occurrence being rarer and its examples smaller in shallower waters, and
in the seas of northern temperate or arctic regions. It makes its first appearance in the
Chalk-marl, and has been recognised also in the London Clay ; but it is most abundant in
the Vienna, Grignon, Sienna, and other Tertiary deposits.

Genus VI. — Sph^roidina (Plate XII, fig. 13).

303. Hidory. — The first account of the very peculiar type known under the name of
Sjjharoidina seems to have been given by M. D'Orbigny in 1 825 (lxix) ; but he confesses himself
to have so far misunderstood its plan of growth, as to have erroneously placed it among his
Enallostiijues. Subsequently (lxxiii) he was induced to place it among his Jr/afliisfer/ues, in
immediate association with the Milioline series, to which its relationship, according to our
view, is analogical only.

304. External Characters and Internal Structi(re. — The shell of Spliaroidina is most dis-
tinctly vitreous and perforated ; but its parous texture is finer than that of Glohigerina. It
consists of a series of segments which succeed one another in a loosely turbinoid spire, having
but four or five chambers in each turn. These segments are turgid and vesicular, like the
chambers of Glohigerina ; but each invests a large part of the preceding, so that only three
segments are usually visible (Plate XII, fig. 13). The aperture is generally more or less
crescentic in form, and is situated at one side of the last chamber close to the exterior of the
oldest visible segment ; it is partly occupied by a projecting tongue or valve, which strongly
resembles that of Miliola ; and while its form sometimes approaches that of a Spirolocidina
(Plate VI, fig. 18), it as frequently approaches that of a BUoculina (Plate VI, fig. 7). Some-
times its margin has deep radiating notches. — A curious variety is presented by certain examples
of Sphceroidina, whose chambers, instead of being in close contact with one another, are
separated like the segments of a dehiscent fruit ; the intervals, however, being partly bridged
over by shelly bands.

305. Affinities. — It will be obvious, from what has now been stated, that both in the
structure of the individual segments, and in the general mode in which they are arranged,
there is a very close resemblance between Sphceroidina and Globigerina ; the difference between
these types chiefly consisting in the continuous communication of the chambers of the former,
one with another, and in its valvular aperture, as also in the degree in which its earlier
segments are overgrown by its later. There is no real correspondence in plan of growth
between Spharoiditia and Miliola ; so that the only point of resemblance between them con-
sists in the valvular aperture that is common to both.

306. Geographical and Geological Distribution. — It is not a little confirmatory of the
correctness of the place we have assigned to this type, that its habitat should remarkably
correspond with that of Orhulina, Globigerina, and Pidlenia ; the home of these four types
being at depths in the ocean at which other Foraminifera are comparatively rare. It is
lound especially, but not exclusively, in the seas of the warmer regions of the globe. — The first

24

186 FAMILY GLOBIGERINIDA.

appearance of Sphceroidina in geological time is in the Chalk of Bohemia and Westphalia
(lxxxv, xc (^) ; and it occurs in various Tertiary formations, especially those of Vienna
and Sienna.

Genus VII. — Carpenteria (Plate XXI).

307. History. — The genus Ccnyenteria was established by Dr. J. E. Gray in 1858 ('Pro-
ceedings of the Zoological Society,' April 27) on the basis of a remarkable set of specimens
collected by Mr. Cuming in the Philippine seas, which had been supposed by several experienced
Conchologists to be sessile Cirripedia. Dr. Gray was led by his examination of them to regard
these organisms as a connecting link between Sponges and Foraminifera ; the shell being
multilocular and minutely foraminated like that of the Rotaline family of Foraminifera, whilst
the fleshy substance occupying its chambers is strengthened with spicules like those of
Sponges. — The larger number of the specimens of this type in the collection of Mr. Cuming
are attached to the surface of a piece of Pontes (coral) ; other specimens, however, are
adherent to the shells of Peden and Cardita ; and Mr. W. K. Parker has met with them on
the surface of other Bivalves, especially C/tama gi(/as.

308. External Characters. — The ordinary external aspect of Carpenteria, as represented
in Plate XXI, figs. 6, 14 (taken from a group on the surface oi Poritcs, of which the indi-
viduals are in close proximity to each other), at once suggests a resemblance to the Balaniform
type ; the shell being conical, attached by its broad base, furnished with a single definite
aperture at its apex, and presenting an appearance of irregular divisions into triangular seg-
ments, which might easily be supposed to be "valves" bounding a single undivided cavity. On
breaking into the interior of the shell, however, it immediately becomes apparent that the
foregoing resemblance is superficial only ; the entire cavity of the shell being divided into
numerous chambers, which are completely separated from each other by septa, whose lines of
junction with the external wall (indicative of the successional additions which the shell has
received) give rise to the appearance of valvular divisions. And a closer examination reveals
that these chambers are disposed upon a spiral type, each whorl completely investing (save
on the adherent base) that which preceded it, so that only the external wall of the last whorl
is anywhere seen on the surface. In the specimen represented in fig. 7, which is one of the
isolated individuals occurring on the valve of a Pecteti, the shell has a much less regular form,
owing to the more or less complete divergence of the basal portions of the chambers of
the last whorl, and the partial subdivision of some of those chambers into lobes which exhibit
the like divergence. The shelly surface of the wall of each chamber presents a somewhat
areolated aspect, which depends upon its being raised into a multitude of low rounded elevations
(fig. 10); and under a sufficient magnifying power these areolae are seen to be pretty uniformly
marked with minute punctations (fig. 12, a, a). The form of the aperture at the summit of
the cone, of which two examples are shown in figs. 8, 9, presents a striking resemblance to
that of the aperture of the Milioloid Foraminifera. In some of Mr. Parker's specimens, the
oral ring is extended upwards into a tube or syphon at least equal in length to the radius of
the cone.

GENUS CARPENTEllIA. 1S7

309. Internal Struefure. — On breaking away a portion of the external wall of the last-
formed chamber, so as to lay open its interior (as shown in fig. 10), we find that its cavity is
closed-in on every side by its shelly walls, except where it has communications [b, c) with the
apical aperture ; and each principal chamber is partially subdivided by a system of shelly
septa, of which some are more and others less complete. The more complete of these
secondary septa (fig. 10, e, e\ e") resemble the principal septa {cl, d}, d") which separate the
cavities of the chambers, in running from the base towards the apex of the cone ; they divide
the lower portion of each chamber into three, four, or more digitations, which are sometimes
marked by an external lobulation, as shown in fig. 7 ; they stop short, however, about half
or two-thirds of the way towards the apex, leaving the upper third or half of the chamber
undivided. Some of these septa do not reach the opposite surface of the chamber; and the
least complete (./j/',/") form a sort of network of ridges slightly projecting from the inner
surface of the outer wall into its cavity (as shown in vertical section at I, b, b, fig. 18), and
there marking out an areolation which corresponds to that of the external surface. The
areolaj of the internal surface, however, are concave instead of convex ; and the punctations,
which are wanting on the ridges, are set more closely on the depressions between them
(fig. 1 2, b, b, fig. 1 6). The reason of this peculiarity in their distribution will be presently seen.

310. The cavity of the last chamber communicates with the external orifice by a passage
of considerable size ; and the wall of this passage is distinctly continued as an irregular ring
around the apical aperture, so that this aperture may be considered in one sense (as described
by Dr. Gray) to belong to the last chamber alone. But it would be more correct to say that
each chamber as it is formed conceals, than (with Dr. Gray) that it closes, the aperture of the
preceding chamber ; for a careful examination shows that the external aperture or vent is the
termination of an irregular vertical canal, formed by the superposition of the oral rings of
successive chambers ; and that through this canal the previously formed chambers retain
their original connexion with the exterior. The general disposition of the chambers around
the central canal is well shown by sections of the cone taken parallel to its base (fig. 11);
such sections, however, may only bring into view the last or superficial whorl ; and they will
generally show only one or two chambers in communication (as at b, c) with the vertical
canal a, the communicating passage of each chamber being on a different plane.

31 1. The foramina which pierce the outer wall of each chamber are of considerable size,
as compared with the minute tubuli characteristic of the Nummuliitida, and they are not nearly
so closely approximated ; in both respects they correspond closely with the foramina of the
ordinary BotalicB and Globigerina. In fig. 1 3 they are shown as they appear in a section
traversing the wall somewhat obliquely to its surface, whilst in fig. 18 thev are shown as they
appear in vertical section ; and in each case they are seen to present an annulated appearance,
which is due to constrictions of the tubes at tolerably regular intervals. These tubes generally
pass direct from one surface to the other; but at a,a, fig. 18, it is seen that in the neighbourhood of
the ridges which project from the inner wall into the cavity of the chamber, the tubes either
bend or incline themselves in such a manner, that, whilst their external orifices are pretty uni-
formly distributed (fig. 12, «), their w^/'cy/^a/ orifices do not show themselves upon the ridges, but
are crowded together along their bases (fig. 12, b, and fig. 16). The septa, whether j»nV««r^

1S8 FAMILY GLOBIGERINIDA.

(separating the chambers from each other) or secondary (partially subdividing the chambers),
are obviously formed by a doubling-in of the outer wall, so as to make each septum consist
of two laminae (fig. 13, «, a) ; this is seen also in sections of the incomplete septa (fig. 13, b),
as well as of the ridges which may be considered as rudimentary septa (fig. 18, h, b, b). The
two layers sometimes separate from each other, as shown in these figures, so as to leave
intraseptal spaces ; and these form a tolerably regular canal-system, which may be traced
throughout the network of ridges that covers the inner wall of each principal chamber, and,
through the primary septa, into the ring that surrounds the vertical canal (fig. \\,r/,g').

312. Notwithstanding these marked peculiarities in the general plan of conformation of
Carpenteria, a comparison of specimens in difierent stages of evolution, and the removal from
the older specimens of one whorl after another until the original nucleus is arrived at, make
it evident that the early condition of this organism essentially accords with that of the Globige-
rine type of Foraminifera, — its approximation being the closest to Eolalia in general form,
but its tendency being rather towards Globiyerina in the circumstance that its chambers do
not seem to communicate directly with each other, but that each has a separate external
orifice directed towards the umbilicus. Various aspects of this first-formed portion of the
shell, thi'ee of them showing the animal substance contained in the chambers, are seen in
Plate XXI, figs. 1 — 5. Now supposing that a Globigerina were to grow in such a manner,
attached by one of its surfaces, that the walls of its successively-formed chambers came into
mutual contact, and that these chambers were so shaped and so piled one on the other as to
give to the entire shell a conical form, each chamber opening by its own separate orifice into
an umbilical funnel, we should have the essential type (so far as its shell is concerned) of
Carpenteria ; and this is really the mode in which the latter type is superinduced upon the
former, as the development of the organism advances. It is further interesting to observe
that the great size of the chambers which form the superficial whorl of Carpenteria, has every
appearance of being due to the deficiency of that complete segmentation, in the later stages
of growth, which characterises the earlier ; for every one of the lociili marked out by the
ridges projecting into the interior corresponds so closely both in size and general aspect with
an entire chamber of the earlier whorl, that the areolation of the outer wall may be regarded
as a sort of attempt at that complete subdivision of the cavity, which we shall see to be fully
carried out in Heterosteyina.

313. The animal substance which occupies the chambers (figs. 1 — 4) is peculiai'ly
spongeous in its texture ; not only possessing (according to the evidence afforded by the dry
specimens which alone I have had the opportunity of examining) far more consistence than
the sarcode-body of the Foraminifera, but being supported, in the larger chambers at least
(fig. 11), by sponge-like spicules (fig. 17), whose form resembles that of the simplest spicules
of Halichondria, and whose composition is siliceous. — It may be undoubtedly urged that as
the surface of dead Coral and the valves of living as well as dead Shells are frequently covered
with Sponges, any multilocular organism growing on such surfaces might be so penetrated by
the sponge, that all its chambers would be filled by the parasite. The following considerations,
however, seem to me strongly to militate against the applicabihty of such an explanation to
the present case : — 1st. That neither on the surface nor in the substance of the specimen of

GENUS TEXTULARIA. 189

Pontes covered with the cones of Carpenteria, nor on that of the valves of the Pcctrn and
Cardita on which isolated specimens of Catymteria occur, is there the least trace of spongy
structure : — 2nd. That, notwithstanding this marked difference in their hahilafs, all the speci-
mens of Carpenteria yet examined have their cavities occupied by the same spongy substance :
— 3rd. That a firm brownish-yellow substance of far greater consistence than the sarcode of
other Foraminifera is found to occupy even the smallest and earliest chambers of Carpenteria
(figs. 1 — 4, a), filling them so completely that it can scarcely be supposed to be anything but
the animal body properly belonging to them ; and that although the substance in question is
there destitute of spicules (the chambers being too small to accommodate them, as will be seen
by the comparison of figs. 4 and 1 7, allowing for the difference of magnifying power), yet it is
obviously the same with that in which spicules are copiously imbedded in the larger and later
chambers : — and 4th. That notwithstanding the multitudes of sections of various Forami-
niferous shells which I have made during the last ten or twelve years, I have never found
their chambers to be occupied by a parasitic Sponge of any description, even where they
have been completely overgrown by Sponge externally.

314. Affinities. — Although, from the account I have given of the structure of this poly-
thalamous shell and its contained body, it will be seen that I can only partially admit the
correctness of Dr. Gray's original comparison of the organism to the papilla of a sponge
enveloped in a shelly case with a single terminal oscule, yet we seem fully justified in regarding
it as a very interesting link of connection between Foraminifera and Sponges. Its nearest
relationships are (as just now stated) to the genera Globigerina and Botalia ; and the peculiar
modification of their plan of growth which its shell presents, although by no means removing
it from the category of ordinary Foraminifera, certainly gives it an analogical resemblance to
the Poriferous type, and thus renders it additionally probable that the spongeous body which
is found in its interior is really its own. If this body be not parasitic, its presence obviously
establishes a near and direct relationship between Carpenteria and the Spongiad^.

315. Geographical and Geological Distrihdion. — All the recent specimens of Carpenteria
hitherto known have been obtained from the Indian Ocean. The wide departure which some
of them present from the typical form makes it not unlikely that we are to refer to this genus
certain minute fossils, such as the Chrysaora {Neuropora, Bronn) damcecornis of Lamouroux
from the Oolite, the Thnlamopora vesic/dosa of Michelin from the Greensand, and the
Ceriopora {Thcdamopora, Roemer) cribrosa of Goldfuss from the Chalk, all of which present
characters that differentiate them from the Corals and Sponges with which they have been
usually associated, and suggest their relationship to Carpenteria.

SUB-FAMILY TEXTULARIN^E.

Genus VIII.— Textularia (Plate XII, figs. 14, 15, and Williamson, Figs. 158—168).

5516. History. — Under the comprehensive name Po/ywor/j/^///'?« various examples of what
is now known as the Textularian type were described and figured by Soldani (ci) ; but they

190 FAMILY GLOBIGERINIDA.

were not differentiated by him from other types associated under the same designation. This
differentiation was first made by Defrance (xxix), to whom we owe the estabhshment of the
genus Textularia, which has been adopted by all subsequent systematists. "With this genus
we find the Bigenerina, GemmuUtia, Gaudry'uta, Vcrneuiliiia, and Vithmliiia of D'Orbigny (the
last being the Grammostomum of Ehrenberg) to be not less intimately connected by gradational
links than are the thirteen reputed genera which we have reunited under the genus Noclosarina ;
and we therefore regard them as merely varietal forms of Texhihria. The Candeina of
DOrbigny appears to have more claim to rank as a sub-genus.

317. External Characters The shell of Textularia essentially consists of a binary series

of segments arranged symmetrically on the two sides of a longitudinal axis ; the segments of
one side alternating with those of the other, and each segment communicating with the
segments anterior and posterior to it on the opposite side (Plate XII, fig. 14). As the size
of the segments usually increases progressively, the outline of the shell is generally more or
less triangular ; the apex of the triangle being formed by the first segment, and its base by the
last two. Sometimes, however, the later chambers do not exhibit any progressive increase, so
that the previously diverging sides of the triangle become parallel ; and sometimes they even
undergo a progressive decrease, so that the sides converge again. The two lateral faces of the
shell usually show more or less of compression ; being sometimes nearly flat, with rounded mar-
gins, so that its transverse section is more or less oblong (ex. Figs. 162, 163, 168) ; whilst in
other instances the shell is more compressed, but is most prominent along the axial line, thinning
away at the margins (ex. Figs. 158, 159, 164, 165), which may even be sharply carinated, as in
the T. carinata of D'Orbigny. Sometimes, on the other hand, the two lateral faces, instead of
being compressed, are so rotund that the transverse section becomes nearly circular, so that
the form of the shell is almost conical (ex. Figs. 160, 161). The mode in which the segments
are applied one to the other, also, is subject to considerable variation. In some instances they
are almost spheroidal in shape, and are merely flattened against each other where they come
into mutual contact (ex, Figs. 162, 168) ; but in general they are more or less depressed and
elongated ; and whilst the direction of their longer axes seems to be typically at right angles,
or nearly so, to the axis of growth (ex. Fig. 158), it is sometimes considerably inclined to this
(ex, Figs. 164, 166). It is usually in those very compressed forms which are thinnest at the
margins, that the obliquity of the long axes of the segments is the greatest ; and sometimes
the outer margin of each chamber is prolonged into a sort of spine (ex, Figs. 166, 167).
In these also we often find the inner margin of each segment prolonged across the
longitudinal axis, so as to interdigitate with the alternate segments on the other side.
Between all these forms there is a completely gradational series, as Professor Williamson has
already pointed out (ex, p. 75). Again, some Textularia commence with a flat Operculine
spire, and subsequently change to a liitjii one ; just as certain small long-spired Gasteropods
begin like a Planorbis. Furtlier, in certain attenuated Textularia; from the Red Sea, the axis
of growth slowly twists upon itself, so that the later pairs of alternating segments are at right
angles with the earlier. Thus it is clear that in this type there is no less variety in regard to
external configuration, than we have seen to exist elsewhere. — The aperture is very constant
as to form and position, being a crescentic slit in the inner wall of each chamber close to its
junction with the antecedent segment of the opposite side (ex, Figs. 159, 161, 163, 165, 167).

GENUS TEXTULARIA. 191

In the Textdarim whose segments are most globose, the crescentic aperture may increase in
breadth so as to become semilunar or even gibbous ; whilst in those whose segments are most
depressed it may be narrowed to a mere sht.

318. The proper substance of the shell is hyaline, with large pores usually not very
closely set, though in some varieties more minute and more nearly approximated ; it is occa-
sionally to be observed that the pores open at the surface into deep hexagonal pits. It very
commonly happens, however, that the shell, as it increases in size, becomes incrusted \v'ith
arenaceous particles, which are commonly large and coarse, and which may entirely conceal
the pores from superficial observation ; and in some of the smallest examples from deep
water, the shell-substance appears externally to be almost as completely replaced by an aggre-
gation of fine sand-grains as it is in Lituola or Valmlina. In the coarsest TextMlaria, however,
I have never failed to bring the pores distinctly into view by examining the shell by trans-
mitted light when rendered sufficiently transparent by the removal of the wall on one side ;
and in the smallest and finest I have been able to distinguish the pores in the interspaces
between the sand-grains, when I have made use of a sufficient magnifying power. — It is in
some of the large fossil Textularice that the arenaceous incrustation is the coarsest in its
texture, so as to give the greatest roughness to the surface.

319. Internal Structure. — When the shell is laid open by section, we find that its struc-
ture is of the simple type that might be expected from its external configuration. Each
segment is so applied to those which preceded it, that its inner wall is partly formed by the
inner wall of the alternate segment which it follows, whilst its posterior wall is formed by the
anterior wall of the penultimate segment of its own series. Thus the septal lamella is always
single ; and there is no differentiation between its texture and that of the rest of the chamber-
wall. The apertural passages by which each chamber communicates with that which precedes
and with that which follows it, are very near to each other ; as is well shown in Plate XII,
fig. 14, which represents the body of the animal and the membranous basis of the shell after
the removal of its calcareous substance by dilute acid, and in Plate XXII, fig. 9, which
represents a siliceous cast of the body of a Textularia from the Greensand. It thus becomes
obvious that the plan of growth depends upon the oblique gemmation of the successive seg-
ments of the animal body, alternately towards one side and then towards the other; and it is
very easy to see how such a bi-serial arrangement may become either uni-serial or tri-serial.
— In some of the largest fossil Textularice, the principal cavities of the chambers are irregu-
larly subdivided by secondary partitions, as in Lituola.

320. Suh-generic Mollifications. — The genus Bi(/erina of D'Orbigny is nothing else than
a Textularia which passes from the bi-serial to the uni-serial plan ; the alternating arrangement
of the segments giving place to a single rectilineal succession resembling that of Nodosaria ;
and the aperture becoming central and circular, sometimes with a lip that may even be slightly
elongated outwards into a tube. A like change in the plan of growth, the aperture remaining
marginal, gives rise to the form distinguished by D'Orbigny as Gemmulina. In the Gaudnjina
of D'Orbigny, again, the arrangement of the chambers is at first tri-serial, as in the typical
Valvulina (f 220) ; but in the course of growth, the tri-serial alternation gives place to the

192 FAMILY GLOBIGERINIDA.

bi-serial. And in the Verneuilina of D'Orbigny, the arrangement may either remain tri-serial
through all the stages of growth, or may become " bulimine," or may give place to a uni-serial
succession, in which last case the shape becomes nail-like, so nearly resembling that of some
ValvuHntB (^ 221) as only to be distinguishable by the want of the valve characteristic of the
latter. The genus ClavuUna of D'Orbigny is made up of these clavuline varieties of ValvuHna
and Verneuilina. — The Vuhulina of D'Orbigny (the Grammostomiim of Ehrenberg) , on the other
hand, is a very obliquely chambered Texfularia, of which the aperture is a narrow fissure,
situated at the most anterior portion of the segment, and lying parallel to the plane of com-
pression (Plate XII, fig. 15). This form, too, may become uni-serial. — In all these modifica-
tions of the Textularian type, the shell is as frequently arenaceous as it is in the typical
Textularia; it is an arenaceous example of the A^erneuiline type, which is figured by Professor
Williamson (ex. Figs. 1 36, 1 37) under the designation BuUmiiin areimcea. — Lastly, the Ccuuleina
of D'Orbigny is a form in which the chambers present the " globigerine " shape and looseness of
aggregation, and are disposed with something of a tri-serial or " verneuiline " arrangement in a
turbinoid spire ; the aperture is represented by him (lxxiii) as an elongated fissure biidged over
by bars of shell so as to be divided into a row of pores ; but these pores do not represent the
true aperture, being only the ordinary pseudopodian passages of the shell- wall, which are pecu-
liarlv large and crowded together along the side of the septal line of the newest chamber. In
its mode of growth this sub-genus is so closely paralleled by Verneuilina [Bulimina, Egger)
py(/mcpa, that it may be questioned whether its distinctive modification is of more than varietal
importance.

321. Affinities. — It is obvious from the intimacy of the relationship between the tri-
serial, bi-serial, and uni-serial forms of Textularia, that we are to regard it as essenti-
ally a trochoid spire, of which the chambers may be three or two in each turn, or which may
straighten itself out by the rectihneal instead of the zig-zag gemmation of its segments. In
some of the small loosely-piled varieties of Textularia, there is obviously a very near approach
to Glohigerina in the form and disposition of the segments. On the other hand, its larger tri-
serial and more trochoid forms tend on the one hand towards certain aberrant forms of the
Bulimine series, and on the other towards the arenaceous Vahuinia, to which genus, as already
explained, their relationship is extremely close.

322. Geographical Distribution. — This type is among the most cosmopolitan of Foramini-
fera ; presenting itself under some of its forms in sands from all shores and in dredgings from
shallow or moderately deep waters. It occurs in greatest abundance, and attains its largest
size, in the tropical and warmer temperate seas ; its finest examples ranging from shallow
waters to a depth of 200 or 300 fathoms.

323. Geological Distribution. — The Textularian type can be traced very far back in geo-
logical antiquity, being recognisable even in the Palaeozoic period. It becomes much more
abundant and varied, however, towards the end of the Secondary period ; its siliceous casts
being common in the Greensand, and its shells being frequently met with in the Chalk. It
is in the Tertiary strata, however, that its fossil forms present their greatest multiplication
and diversity ; and the various modifications of this type at present existing are closely

GENERA CIIRYSALIDINA AND CUNEOLINA. 193

paralleled by those which occur in the Miocene and Pliocene deposits of Vienna and
Palermo.

Genus IX. — Chrysalidina (Plate XII, fig. 16).

324. Hisfori/. — This genus was created by D'Orbigny in 1846 (lxxu), for the reception
of a peculiar modification of the Textularian type, which, so far as is at present known, is not
connected with it by any intermediate gradations.

325. Ed-tenal Characters and Infernal Structure. — The name of this genus expresses the
pupoid form of its shell, which results from the tri-serial arrangement of its chambers, and
from the peculiar oblique mode in which they are set one upon another, as shown in Plate XII,
fig. 1 6. The essential difference of this type, however, from JWttdaria appears to consist in
the mode of communication of the chambers ; for the apertural passages by which each cham-
ber of one series communicates with the alternating chambers of the adjacent series in the tri-
serial Textdarice seems to be here wanting ; being replaced by a set of very large " orbuline"
pores, which are dispersed over nearly the whole anterior wall of the last chamber. These
pores, which have fully twice the diameter of the ordinary pores of the shell, are sometimes
continued externally into short tubes, which project fully the lengtli of their own diameter
from the convex septal plane. From the mode in which the older segments are partially
overlapped by the newer, the communication between each chamber and that which succeeds
it in the spiral alternation will be maintained by those pores which pass through that part of
the anterior wall which forms the posterior wall of the next chamber. — The most characteristic
specimens of this type present themselves only in the Lower Chalk, near the mouth of the
river Charente ; but small dimorphous examples of it are met with in the Indian Ocean and
Panama Bay, which, commencing tri-serially, soon take on a uni-serial mode of growth,
continuing to maintain their triangular form to the end, and progressively increasing the
size of their segments, which is contrary to the rule of uni-serial growth in other bi- or tri serial
types.

Genus X. — Cuneolina (Plate XII, fig. 17).

326. History. — The first and only original account of this curious type is that which was
given by M. D'Orbigny (lxxi) in 1839, on the basis of specimens found only (hke those of
the preceding type) in the Lower Chalk, near the mouth of the Charente.

327. External Characters and Internal Structure. — The form of this shell (Plate XII, fig. 1 7)
is that of an almost equilateral triangle with a curved base ; and its two flattened surfaces are
marked by a succession of parallel curved septal bands, apparently indicating a uni-serial suc-
cession of chambers whose breadth bears an unusually large proportion to the distance
between the septa. When the shell is viewed edgeways, however, it is seen that the two
external surfaces belong to two different series of chambers, whose internal surfaces are closely
applied to each other ; and it is further to be noticed that the chambers of the two series

25

194 FAMILY GLOBIGERIXIDA.

alternate with each other. The aperture consists of a number of distinct pores arranged
in a single series along the whole extent of the apertural plane, as in the most flattened form of
Peneroplif! ; and these are so obliquely disposed, that each chamber communicates by their
means with the alternating chambers below and above it in the opposite series.

328. Affinities. — It is obvious from the preceding description, that CuneoJina is nothing
else than a Tcxtidarin which is extremely compressed in a direction transverse to the normal
direction of its compression ; for if we could imagine a Textularia with globose chambers to
be composed of a plastic substance, it can be easily conceived that whilst by pressure applied to
the two axial /«ci"5, those two faces might be extended and thinned out until they presented
the flat triangular shape which distinguishes CuneoUna — each face being divided by the axial
line, on the two sides of which the two series of chambers would still be disposed, — a
like pressure applied to the two margins would flatten the two series of chambers
against one another, so as to convert what were before the margins into lateral faces,
and to bring to what were before the axial faces into the condition of margins, as occurs in
certain aberrant Biloculincp. The same change would convert the wide crescentic aperture of
the ordinary Textularia into a narrow elongated fissure ; and it is obvious that the conversion
of this into a row of detached pores does not in itself remove CuneoUna further from the
Textularian type, than Peneroplis is distant from Dendrifina, or Calcarina from Motcdia.
Intermediate gradational forms being iiere wanting, however, CuneoJina must, for the present
at least, be ranked as distinct Irom Textularia, though in close proximity to it.

Genus XL— Bulimina (Plate XII, figs. 18—22 ; and Williamson, Figs 124—135).

329. History. — ^The peculiar type to which the name Bulwmia (expressive of the Bulimus-
like form of its spire) was given by D'Orbigny (lxxiii) in 1825, does not seem to have been
recognised by any preceding systematist. It has been since generally adopted in tlie sense
in which it was originally employed ; but we shall use it as the generic designation not merely
for the forms included under Bulimina proper, but also for those belonging to the sub-genera
Virgulina and BoUvina, which were instituted as genera by D'Orbigny, but were regarded by
him as allied rather to Textularia than to Bulimina.

330. External Characters and Internal Structure. — In its typical form the shell of
Bulimina is composed of a series of spheroidal segments progressively increasing in size, and
so applied to one another by their flattened faces as to form a " bulimine" spire (Plate XII,
fig. 18). The aperture is a loop-like notch in the convex wall of the last chamber,
extending forwards and outwards, usually with more or less obliquity, from its umbilical mar-
gin ; its shape is such that it seems as if it were formed by the folding over and convergence
of the two halves of the anterior wall of the chambers (Plate XII, fig. 18), and it is noticeable
that these do not commonly meet at the umbilical angle, but that one passes obliquely behind
the other. The margin of the aperture is usually somewliat lipped externally ; on the other
hand, it is sometimes prolonged externally into a little narrow tubular neck. The shell of the
smaller forms and younger specimens of Bulimina is hyaline and very translucent, and it's

GENUS BULIMINA. 195

porous structure is considerably finer than \.\nioi Tcainhirin; the hyaline surface is never lost
in the recent examples of this type ; but the larger and older fossil specimens very commonly
have the shell incrusted by an adherent layer of arenaceous particles. Such arenaceous
forms are very common among the Bulimince of the Cretaceous deposit, of which an example
is here figured (Plate XII, fig. 18). In the BuJimince, as in the Ttwtidarite, the aggregation of
segments takes place upon the simple plan which is common to the lower forms of the vitreous
series with the whole of the porcellanous ; the anterior wall of each chamber serving as the pos-
terior wall of that which succeeds it, and the septal laminee being single and not differentiated
from the ordinary wall of the chamber. There is therefore neither intermediate skeleton nor
canal-system.

3-n. Departures of greater or less extent from the typical character of this genus are
extremely common ; and such departures are especially liable to occur in regard to the plan
of growth, to the form and setting-on of the chambers, and to their surface-ornamentation.
Thus the obliquely spiral succession of the segments may be so modified that they come to
present a more or less distinct tri-serial arrangement, ofwhich wehave a striking illustration in
the B. Biichiana of D'Orbigny (Plate XII, fig. 19), whilst the ordinary B.pupoldcs (ex. Figs.
124, 125) presents it in a less obvious degree; and in a variety of this last form termed
fusi/onins by Prof. Williamson, the segments are chiefly added in /m>o instead of in three oblique
series, so that the form becomes compressed (ex. Figs. 129, 130). A still greater modification
is effected by the uncoiling of the spire, so that the later segments present a uni-serial recti-
lineal succession, and the form of the entire shell becomes " spirohne ;" of this we have an
example in the varietal form described by Prof. AVilliamson as coiivolida (ex, p. 6.'}, Figs.
132, 133), of which he remarks that "it presents almost as many modifications as individual
specimens."* The same condition sometimes presents itself in the B. elef/antif<f:iiua of the
Indian seas ; which also sometimes puts forth a few feeble " wild" segments out of the regular
axis of growth. In other varieties, again, the ventricose form of the segments is modified in
a greater or less degree by flattening or by drawing out in some particular direction. Thus
the earlier segments may be more or less completely enclosed by the backward extension of
the later. Of such backward extension we have an incipient example m B. marcjinata (xc,
Figs. 12G, 127), but it is carried to its fullest extent in B.p>jrida (Plate XII, fig. 20), in which
the later segments so completely enclose the earlier, that only the last three are at any time visible.
By a lateral elongation of the segments, the obliquity of their setting in relation to the axis
of the spire, and the flattening of their borders one against the other, that peculiar varietal
form is produced which has been distinguished by M. D'Orbigny under the generic desig-
nation Bobertina (Plate XII, fig. 21) ; and it is a singular instance of that want of power to
discern the real aflinities of the types he described, which I believe to have been induced by
his misplaced confidence in plan of growth as the only trustworthy guide in the
classification of Foraminifera, that he has not only separated this well-marked Bulimine type

* This form is veganlcd by Prof. AVilliarason as a 4(-serial -B. piipoides partly rolled upon itself ;
but he seems to us to have been misled by the split appearance which the shell acquires from the suc-
cession of the fissured apertures of a ufii-seiial row of segments ; and we cousider it, as above stated,
rather as an uncoiled than as an abuormallv convoluted form.

196 FAMILY GLOBIGERINIDA.

generically, but has even transferred it from his order Helicostegues to that of Entomosteffues,
under the influence of a misconception as to the real arrangement of its segments, without
giving any other hint of its relationship to Bulimina than that which is afforded by his likening
of the form of the entire shell to a minute Bulimus. In our view Rohert'ma is only one of the
numerous varieties presented by the B. clcgantissima of D'Orbigny ; in some of which the
segments are extremely elongated laterally, and are set very obliquely to the axis of the spire,
so that its last turn, consisting of from seven to ten segments, almost completely encloses the
preceding, and the whole shell may have much more the form of an OVam than that of a
Bulimus (ex, Figs. 13-1, 135) ; whilst in its largest and best developed forms, which occur in
Arctic regions, the alternating segments interdigitate with each other.

332. A general ornamentation of the surface is not common in this type, though we
sometimes meet with a longitudinal costation (Plate XII, fig. 19) strongly resembling that of
TJmfjerina. This costation may be confined to the earlier segments, the later being quite
smooth. The more usual kind of exogenous growth in this type consists in the prolongation
of the posterior margin of the segments, in those varieties which are characterised by their back-
ward extension; this prolongation may consist in a mere serration, as in the B. maryinata
(ex, Figs. 126, 127), or it may go so far as to produce a fringe of long transparent spines, the
several segments of the same shell often exhibiting intermediate gradations between these two
extreme conditions. In the most spinous varieties the shell itself is generally stronger than
in the smooth forms ; on the other hand it is thinnest in the most elongated examples, which
seem to be starved out.

333. We have seen that even in tiie ordinary Bulimine type there is sometimes a
tendency to a binary or Textularian alternation of the segments; this, however, is much more
marked in certain extremely elongated forms, having a tliin delicate shell that is never
arenaceous, and the aperture greatly elongated but still preserving its Bulimine character.
To such forms the generic name Virgulina has been applied by D'Orbigny ; but their
degree of departure from the Bulimine type is not even of specific importance, as Prof.
Williamson has shown himself to have perceived, by ranking them as varieties of his
B. piqjoides. — A more decided modification of the Bulimine type is presented by those forms
which have been ranked by D'Orbigny in his genus Bolivina, the arrangement of the seg-
ments being here regularly bi-serial and alternatmg, as in Textularia ; but the aperture never
loses the elongation and the inversion of its lips characteristic of the Bulimine type, and
its direction is usually somewhat oblique. In the B. cosfatn of D'Orbigny (Plate XII, fig. 22)
there is a set of eight parallel costse, running continuously from one segment to another
along the entire length of the shell, giving to it a very peculiar aspect.

334. Affinities. — It is obvious from what has just preceded, that the affinity of 5«//m/»« to
TexMaria is very close ; since Bolivina will rank under one or the other of these generic types,
according as we attach the greatest value to the character of the aperture or to jwfo-v of growth.,
as an indication of natural affinity. That the former has a far stronger claim to acceptance
than the latter, appears obvious from the fact that, as we have seen, the plan of growth may
vary in unquestionable Bulimina from a continuous succession of segments in a bulimine spire

GENUS CASSIDULINA. 197

to a tri-serial or bi-serial alternation, and that in unquestionable Textularim the bi-serial
arrangement may give place to the tri-serial or even to the bulimine ; whilst through all these
variations the form of the aperture characteristic of each type is constantly maintained.
The relation of the large sandy BuUmince to the "bulimine" Valmdina (^221) is extremely
intimate ; the form of the segments and their mode of aggregation being the same ; the
originally porous texture of the shell being common to both, and being liable in both to be
afterwards more or less completely occluded by arenaceous aggregation ; and the difference of
type being marked only by the aperture. The feebler forms of BuUmina are related, like those
oi TcvtuJarina, to Globit/erina ; and in some of the loosely piled tri-serial Bulimi/ice there is a
strong general resemblance to certain JJvigerince, the chief differentiation being in the aperture.
On the other hand, in BoJivina punctata, which combines a crescentic curvature of the entire
shell with a bi-serial arrangement of the segments and a very obhque aperture, we have an
obvious tendency towards Cassidulina, in which form the series appears to culminate.

335. Geo(/raj)ldcal Distribuiion. — There seems to be a close correspondence between
BicUmina and TextuJaria as to the conditions most favorable to their development, as they
are generally found under the same circumstances ; the latter, however, being commonly
much more abundant than the former,

336. Geological Distribution. — This genus has not as yet been traced, however, quite so far
back in geological time as Textularia, its earliest appearance, so far as we at present know,
having been in the Upper Trias, in which small examples of it are found ; it occurs in the Oolitic
formation and in the Chalk-marl, in which last deposit and in the Chalk some of its finest
examples present themselves. It occurs under some or other of its forms through the whole
Tertiary series, from the London Clay to the most recent formations ; some of its most remark-
able varieties being found in the Vienna and San Domingo deposits.

(?e«K5 XII.— Cassidulina (Plate XII, fig. 23; and Williamson, Figs. 141—144).

337. History. — This genus was first established by M. D'Orbigny in 1826 (lxix) for a
peculiar type, which does not seem to have been recognised by any previous observer.

338. External Characters and Internal Structure. — This genus is distinguished from all
other Foraminifera in combining the bi-serial and the convolute arrangement of its segments ;
for although several other genera are associated with it by M. D'Orbigny in his order Ento-
niosti'f/ues, yet in no one of them (as will hereafter appear) does this combination really exist.
The texture of the shell of Cassidulina is hyaline and finely porous, like that of the smaller
Bulimiiice ; and it resembles that type also in the characters of its aperture. In fact, if we
imagine a bi-serial BuUmina to be completely rolled upon itself, so as to form an equilateral or
nearly equilateral spire, we should have the essential features of a Cassidulina. The arrange-
ment of the chambers, as it shows itself externally, has a semblance of irregularity which does
not really belong to it; the apparent irregularity being really due to the interdigitation of the

19S FAMILY GLOBIGERINIDA.

chambers of the two alternating series, some of which may be made to appear by the obliquity
of the spire as if they were small and intercalated (ex, Fig. 141). The earlier turns of the
spire are in general completely enclosed by the later ; but sometimes the axis of the spire is
so oblique, that much more of the earlier portion is seen on one side than on the other. The
septal plan is flat and oblique, facing alternately towards opposite sides ; and the aperture is a
curved slit, commencing at the junction of the septal plane with the preceding convolution, and
extending about half way across the septal plane, usually in a direction parallel to its lower
edge (ex, Figs. 141, 142), but sometimes becoming crozier-shaped, as in some of the uncoiled
varieties, or even doubling abruptly back upon itself, so as to form a kind of valve or tongue,
as in the C. crn.-im of D'Orbigny (lxxiii). The general form of the shell is subject to
variations similar to those which we have seen to present themselves in BuUmhia and
Te.riidariri ; the segments being ventricose in some instances, and flattened in others ; and the
margin being obtuse and rounded in some instances, thin and carinate in others. — A much
greater departure from the typical shape is presented by the Ehrenhergina of Reuss (lxxxvii),
which is a Cassidulina in every essential particular, but has the later portion of its spire uncoiled,
showing very clearly the bi-serial interdigitate arrangement of the segments (Plate XII, fig. 23).
After the evidence which has been given in such genera as Peneroplis and Xodosaria of the
little reliance to be placed on the direction of the axis of growth as a differential character,
it is impossible to regard Elirenheryina as anything but a varietal form of Cassididbia.

339. Affiniiies. — This genus may be regarded as the culminating form of the Textularian
series, which nowhere graduates into any type of a character more elevated than its own. In
the finely porous texture of its shell and its slit-like aperture, it is obviously more allied to
BuUmhifi than to Tcxtularia ; whilst, in the bi-serial interdigitate arrangement of its chambers,
it is more closely akin to Textularia than to the typical Bidiniina.

340. Geographical and Geological Distrihition. — Like the preceding genus, Cassidulina seems
to have a world-wide distribution in shallow, moderately deep, or even very deep waters ; being
found at depths of from thirty to seventy fathoms on the west coast of Greenland, also off"
Norway, Shetland, and various parts of the British and Irish coasts ; whilst the larger and
thicker forms with smooth shining walls occur in tropical seas at depths of from thirty to
one thousand fathoms. — This genus presents itself in the Tertiaries of New Zealand (Eocene?),
Menna, Sienna, and Palermo ; but it has not been recognised in any older formations.

SUB-FAMILY ROTALIN^.

341. The assemblage of forms which constitute in our view the Eofalinc sul>family or
series is the most numerous and the most varied that is presented by any corresponding
group ; and as a consequence of that variety, the relations of these forms to each other have
been singularly misconceived. Misled by superficial differences masking real resemblances,
M. D'Orbigny created several genera for their reception, which in our view have no title
whatever to that rank. On the other hand, his ignorance or his want of appreciation of
differences of far greater importance, led him to associate in the same genera types which

SUB-FAMILY ROTALINiE. 199

Messrs. Parker and Rupert Jones have been brought by a careful study and extended
comparison to regard as essentially distinct. Thus a new distribution of the entire group
becomes requisite, neither of our genera having the same value with any one of D'Orbigny's ;
and as the whole group constitutes an extremely natural series, of which there is much to
be said in common, it will be convenient to treat of such generalities under this head, ratlier
than to disperse them among the separate sections which will treat of the peculiarities of
individual genera.

342. Hidorij. — Every systematist who has attended to such minute shells, has had his
notice attracted by examples of the Rotaline series. Thus tlie world-wide typical Rofalia
Beccarii and the tropical Calcarina Sjjevyleri were both described in Gmelin's edition of the
' Systema Naturae' under the generic designation Nautilus. A large number of Rotaline
forms were described and figured in the great works of Soldani (c, ci), under the generic
designations Nautilus and Hanmonia ; many plates being devoted to the protean varieties of
the Mediterranean shell since known as Truiicatulbia variabilis. Boys and Walker (ix)
described as British species of Nautilus not only the N. Beccarii (of the common " reversed"
form of which they made a distinct species), but also N. lobatulus and N. umbilicatulus, which
are varieties of the form since generally known as Truncalulina lobatula. Montagu (lxv)
also enumerated N. Beccarii among British species ; but he gave the generic name Serpula
to two Truncatuline forms which we now place with T. variabilis and 1\ lobatula in our genus
Plaiiorbulina. The admirable work of Fichtel and Moll (xLv) contains numerous figures of
the varieties oi Nautilus (Calcarina) Sj^engleri ; they distinguished as N. repamlus the Rotaline
form which we now differentiate as the typical Pulvvnulina repanda, other varieties of which
they designated as N. sinuatus and N. auricula ; and they gave the name of N. farctus to the
Rotaline form which we shall ditferentiate as Planorbulina farcfa, another variety of which
they designated as N. tuberosus. The name Rotalites was first introduced by Lamarck (lvii),
who subsequently (lviii) modified it to Botalia ; and from that time it has met with general
acceptance amongst systematists, having been sometimes further modified into Rotaliiia.
Particular Rotaline forms were further distinguished by Lamarck (lviii and lix) under the
generic names Biscorbites, Biscorbula, and Puloitnilus, for the last of which he afterwards (lx)
substituted Placentula. Although neither of these names has been generally adopted
{Biscorbis having been only employed by Blainville and by some British conchologists), yet,
for reasons to be presently stated, Biscorbina and Pulvinulina will be employed in the present
work as generic designations. A fossil Rotaline form which occurs in the Upper Chalk of
Maestricht received from Lamarck the generic name Siderolites, under a total misapprehension
of its nature ; this name, although admitted by D'Orbigny, must now be dropped, since I shall
show that the type which was designated by it is only a variety of the long previously
known Nautilus (Calcarina) Spengleri. It was of course to be expected that Montfort should
institute many new genera for the varietal forms of this group ; and accordingly wo find the
names Cidarollus, Cortalus (?), Cibicides, Eponides, Stordus, and Polyxcnus, applied to as many
Rotalines ; whilst the name Tinoporus was conferred upon a peculiar type which he seems to
have been the first to distinguish from Nautilus (Calcarina) Speiit/leri. All these names have
long since been discarded as unnecessary synonymes ; but we shall revive the last, for reasons
which will be stated hereafter (^ 390).

200 FAMILY GLOBIGERINIDA.

343. Such was the nomenclature of the group when it was first taken up by D'Orbigny ;
who, in his first systematic arrangement of the Foraminifera (lxix) created, in addition to
Rotalia, the genera G yroidina , Planorbulina, TruncatuUna, Anomalbm, RomUna, CaJcarina, and
Turhinolina ; to which he subsequently added Asterlgerina (lxxi), whilst he abandoned Gyroidlna
as not sufficiently differentiated from Rotalia, and Turhinolina as not sufficiently differentiated
from Bosalina. To these the genus Siphonia has been added by Reuss (lxxxvix) ; and the
genus Jcervulina by Schultze (xcvii). — On the other hand, by Prof. Williamson (ex) the genera
Boialina and Rosalina have been reunited, for the excellent reason that tlieir distinctive
characters are such as a mere difference of age suffices to destroy ; and he further correctly
stated that (as had been in some degree divined by M. D'Orbigny himself) certain shells
ranked by D'Orbigny under the genus FalvuHna are true Rotalines.

344. The Rotaline type has been specially studied by Messrs. Parker and Rupert Jones,
■who have found it requisite to throw together again all the genera Rotalia, Planorbulina,
TruncatuUna, Rosalina, Asterigerina, Anomalina, Planulina, and Calcarina of D'Orbigny, together
with several species of his Valvulina, as well as the Siphonia of Reuss, and the Acervulina
of Schultze ; and to rearrange the resultant aggregate of forms upon entirely new principles
under six genera, — viz., Rotalia, Calcarina, Planorbulina, Puloinulina, Discorbina, and Cymba-
lopora ; for the first three of which they employ the names previously given by D'Orbigny,
but in a different sense. Regarding Rotalia Beccarii as the type of the true Rotalia, and
Calcarina Sjioiyleri as the type of the true Calcarina, they arrange under those genera respec-
tively such forms as correspond with their types in all essential particulars ; and thus it comes
to pass that the Rotalia of Messrs. Parker and Rupert Jones corresponds with parts of
the Rotalia, Bosalina, Gyroidina, Asterirjerina, and Calcarina of D'Orbigny ; whilst their
Calcarina includes part of the Rotalia of D'Orbigny with part of his Calcarina. The Planor-
bulina of Messrs. Parker and Rupert Jones has a scope very different from the Planorbulina
of D'Orbigny ; for it reunites parts of D'Orbigny's Rotalia, Rosalina, and Anomalina, together
with TruncatuUna, Planulina, and Acervulina (Schultze), to part of D'Orbigny's Planorbulina.
The genus Pulvinidina, of which the type is the Rotalia repanda (the Pulvinulus rcpandiis of
Lamarck), includes parts of the genera Rotalia, Planorbulina, and Valvulina of D'Orbigny ; and
in like manner the genus Biscorbina, of which the type is the Rotalia turbo (of which one
variety had been named Biscorbites vesicularis by Lamarck), is made up of parts of the genera
Rotalia, Rosalina, Valvulina, Asterigerina, Anomalina, and Globigerina of D'Orbigny. Lastly,
the genus Cymbalopora consists of a small group of very peculiar forms which had been
included by D'Orbigny in his genus Rosalina.

345. The typical genera of the Rotaline series are those in which the shell essentially
consists of a succession of coarsely porous or Globigerine segments, arranged in a turbinoid
spire, and communicating with each other by a cresentic aperture situated at the janction of
the septal plane with the free surface of the convolution. The pores (Plate XIII, fig. 1),
in characteristic examples of the Rotahne series, are from l-2000th to l-5000th of an inch
in diameter ; they are usually larger on the external surface than on the internal, as is
shown by sections which traverse the thickness of the shell (fig. \, b); and it very commonly
happens that each external orifice lies at the bottom of a sort of funnel that is formed by a

SUB-FAMILY ROTALINiE.

201

circular ridge of shell, so that the whole surface is marked out into minute areolje (fig. I, a).
The segments progressively increase in size, and the earlier whorls are scarcely at all invested
by the later; so that the whole spire remains visible on one lateral surface, whilst on the other
side nothing is seen except the last convolution. Generally speaking, the former (as in a
Turbo or Trochus) is more or less conical or convex, the primordial chamber occupying its
highest point, whilst the latter or growing side is more or less flattened ; and as it is ordi-
narily by the latter that the shell is adherent to the sea-weeds, zoophytes, shells, or stones, to
which the animal commonly attaches itself during life, this may appropriately be called the
lower surface, whilst the former, which is free, is distinguished as the upper surface (Fig. XXXII,
A, b). We agree with Prof. Williamson (ex, p. xvi) in thinking it desirable to retain these terms
as morphologically correct, in cases in which the side whereon the whole spire is visible is the
flattest (Fig. XXXII, d, e), the spire having more the form of a Conns than of a Turbo or
Trochus; notwithstanding that, the shell being attached by the flatter side, the position of the
animal is (so to speak) inverted. — As a general rule in this series, the anterior portion of the
wall of each segment forms the posterior wall of the chamber that succeeds it, the septal layer
being single and not being differentiated in texture from the ordinary chamber wall, so that
there is neither intermediate skeleton nor canal-system : to this rule, however, there is a
marked exception in the genus Rotalia, which approaches the NummuUnida in the duplication
of its septal laminre and in the existence of intraseptal spaces ; and there are many other cases
in which the usual porous texture of the shell gives place, in the portion of the chamber wall
forming the septal plane, to a hyaline plate that displays none but large perforations.

Fig. XXXII.

\aiious forms of Rotalines .- — a, PulcinuUda bademis, Czjek; b, Discorbina dimidiafa, Jones and Parker; c, jMmalLia puncltt-
luta, D'Oibigny ; D, Truiicalidina loliidida. Walker and Jacob ; a, TruiicaliiUna i-efulrjeiis, Montagu ; r, I'latmlim
Anmhiensis, D'Orbigny ; G, ttiscorbina bi-conanu, Junes and Parker.

346. The form of the spire, and that of the segments of which it is composed,
may difl'er very widely. As already stated, the tiirbinoid form, in wliicli the spire is
somewhat depressed and more or less spreading, and in which the individual segments ai'e
more or less ventricose, may be considered as the one most characteristic of the group
(Fig. XXXII, b). But, on the one hand, the spire may be as high, as regular, and as compact,
as that of a Trochus ; the shape of the segments being such that the outer surface of each is

26

202 FAMILY GLOBIGERINIDA.

" flush" with that of the cone as a whole ; whilst they are so closely applied to each other
that their septal planes become nearly fiat. On the other hand, the depression of the spire
may be so great that its superior lateral surface becomes completely flattened ; and in this
case it may happen that, if the inferior surface remains flattened, the shell may become almost
exactly symmetrical (c), and in extreme cases complanate (f), or even bi-concave (g) ; whilst
the segments may be so disposed as to render the inferior lateral surface convex (u), or even
conoid (e). Again, the segments may be so ventricose and so loosely attached to each other,
that the spire is scarcely closer than that of a Glohigerina ; and there are even cases in which
their arrangement approaches that which is characteristic of Textularia. In most of the forms
in which the spire is elevated, the chambers of the later convolutions do not extend inwards
so as to reach the axis, but leave an "umbilical vestibule," which is sometimes of considerable
dimensions (ex. Figs. 91, 102) ; this, however, does not ordinarily communicate (as in Glohlge-
rind) with the cavities of the chambers ; and it is frequently filled up by solid shell-substance.

347. The external aspect of the shell in this genus is often considerably modified by an
exogenous deposit of non-porous shell-substance, sometimes translucent, sometimes opaque.
Such a deposit very commonly presents itself along the septal bands, converting what would
otherwise be fossae into elevated ridges, which may become continuous at their extremities
with a similar deposit that forms the outer border of the spire (ex, Figs. 101, 103, lOG, 112) ;
in many instances, again, a like deposit forms a sort of columella in the axis of the spire,
which shows itself more or less prominently on the inferior lateral surface ; whilst in other
cases its presence is chiefly marked by tubercular elevations on the general surface, which are
usually more abundant on the lower side than on the upper. The marginal deposit occasionally
extends itself, as in CristeUaria, into radiating spire-like prolongations ; but these, in the
ordinary Rotalines, are neither large nor numerous. In the ^e.nVi% PlanorbuKna we occasionally
find the general surface beset with prominent tubercles, between which the pores are crowded
together (Plate XIII, fig. 15). It is in the genus Calcarina, however, that this exogenous
deposit is most remarkable (Plate XIV) ; the whole of the spire being invested with an
extraordinary thickness of homogeneous shell-substance, which sends out numerous large
extensions, and for the nutrition of which an elaborate canal-system is provided. It is not a
little singular, however, that this canal-system does not extend to the interior of the spire,
which is constructed upon the simplest Rotaline type, and which, although externally masked,
is usually very regular.

348. A very curious feature presented by several modifications of the Rotaline type, is
the development of " asterigerine" flaps of shell- substance (Plate XIII, fig. 3), which radiate
to a greater or less distance from the umbilical depression on the lower surface, and
apparently serve to cover-in secondary lobes of sarcode-substance. These flaps are sometimes
so complete, and are disposed so regularly, as to inclose a set of secondary chambers alter-
nating with those of the primary spire ; whilst in other cases they are merely rudimentary.

349. In many forms of the Rotaline series, the typically spiral mode of growth gives
place either in an earlier or a later stage of existence to the cyclical. Some approach to this
is seen in the flat vermiculate forms of PuIvinuUna ; it is very evident in the advanced condi-

GENUS DISCORBINA. 203

tion of Cymbalopora ; but it is in PlanorbuUna, among the typical Rotalines, that the cychcal
plan most completely prevails over the spiral, and replaces it at the earliest period. The
truly Rotaline character of this type is evidenced by the frequency of its " truncatuline" and
" anomaline" forms, these being merely PlcuiorhuluKS whose development has been arrested.
In this genus, moreover, the growth may become altogether " wild," the segments being
heaped up, one on another, in an irregular or " acervuline" manner; and tlius we are led to
the genus Tinoporus, in which the primordial spiral is recognisable with difficulty, and the
piling of segments is combined with a mode of horizontal extension that seems properly
cyclical ; whilst in the genus Poli/trcma all trace of the primordial spiral seems lost, and the
mode of growth seems almost indefinite. In these cyclical and acervuline forms of the i?o/rt//«e
type the aperture of communication undergoes a complete alteration in shape, being no longer
a crescentic fissure, but a circular passage, which is sometimes furnished with a pouting lip
that may be elongated into a tube. — A still more remarkable departure frona the ordinary
type will be found in the genus Patellina ; of which the primitive form seems to be a hollow
conical spire with only two segments in each turn, but each of these segments subdivided
into chamberlets ; this gives place, in the more developed examples, to a regular cyclical
increase, and the hollow of the cone (which corresponds to the umbilical vestibule of the
ordinary Rotalines) is filled up by a more or less regular growth of secondary chambers.

350. The intimacy of the relationship that exists between the several genera which
normally constitute the Rotaline series, is evidenced by the fact, that among tlieir very
numerous varietal forms isomorphs are frequently met with ; these isomorphs often so
closely resembling each other, that it is only after a careful examination of the gradational
affinities of each that its proper position can be assigned. The largest number of such
varietal forms is presented by PlanorbuUna, which has yielded several scores of pseudo-species
to authors ; next to it comes Discorbina ; then Puloinulina, which has from forty to fifty such
forms ; then Botalia ; then Calcarina ; and lastly Cymbalopora, from whose varieties only four
species have been erected. — Of the more aberrant genera, Tinoporus, Polytremn, and Patellina,
the first and third will probably yield a large number of varietal forms when they shall have
been adequately studied ; the second appears essentially amorphous. Even these genera are not
without examples of the isomorphism just alluded to : thus the Tinoporus baculatus so
extremely resembles Calcarina Spent/leri as to be readily mistaken for it by such as are not
familiar with the special peculiarities of each ; and we shall see that in the early stage of
growth there is no essential dissimilarity between them.

Genus XIIL— Discorbina (Plate XIII, figs. 2, 3 ; and Williamson, Figs. 104, 105, 109 — 1 13).

351. External Characters and Infernal Structure. — The genus Discorbina may be regarded
as presenting the characteristic features of the Rotaline series in their simplest, as Rotalia
does in their most developed, condition. Its shell is typically a turbinoid spire, formed by a
succession of vesicular segments, every one of which bears a strong resemblance to a

204 FAMILY GLOBIGERINIDA.

segment of a Globir/erina (ex, Fig. 104 *) ; the only essential difference between the two t}^pes
consisting in this, that each chamber of GJohigerina has a distinct communication with the
umbilical vestibule, whilst in Liscorbina each chamber communicates only with that which
precedes and follows it. The aperture is a large fissure, more or less arched, reaching to the
lower edge of the umbilical margin of the septal plane ; and it is nearly always more or less
occluded by an " astral flap," which may be a mere projection of the exogenous substance
deposited on the umbilicus, or may be part of the more developed " asterigerine " plates to
be presently described. The general form of the shell is conical, with a rather sharp margin
and a nearly flat base.

352. These characters are typically shown in the Rotalia turbo of D'Orbigny, of which
fossil varieties had been described by Lamarck (lviii), under the names Discorbifes vesicu-
hiris, Hotaliles trochidiformis, and R. lenticularis. Of these the R. trocliidiformis of the
Grignon Tertiaries is the largest and most strongly developed, but it is scarcely the most
characteristic; the peculiar features of this type being more conspicuously exhibited by the
Rofalites vesicularis of Lamarck, which is the Rotalia Gervillii of D'Orbigny's models and the
Discorbina vesicularis of Parker and Rupert Jones, and which is very common at the present
time on the Australian coast. The form of this shell (figs. 2, 3) is plano-convex, or concavo-
convex, its umbilical surface being flattened, or even concave, whilst its upper surface is mode-
rately arched. Its segments are vesicular externally, so that its septal bands are furrowed;
and they commonly retain their globose form on their anterior extremity, which forms the poste-
rior boundary of the next segment, and is not difl'erentiated save by the loss of its pores
from the remainder of the chamber-wall. The upper surface may show the spire from its very
commencement ; but as it commonly happens that each later whorl in some degree overgrows
the one which precedes it, the primordial chamber is sometimes concealed. The character of
the upper surface is for the most part but very little altered by exogenous deposit ; though
sometimes the apex of the spire is crowned by a glistening boss of hyaline substance. The
vesicular form of the segments is sometimes retained on the lower or umbilical surface, but
more commonly it gives place to a flattening ; in either case, how ever, there is a deep furrow-
ing at each septal junction, leading towards the umbilical depression. This depression, with
its radiating furrows, is covered in by a sort of tent of hyaline non-tubular shell-substance,
which sends an astral prolongation to attach itself to the wall of each of the surrounding
segments (fig. 3) ; and thus a space is enclosed, which (it can scarcely be doubted) is
filled in the living state with sarcode-substance. Under some condition or other, this
" asterigerine " growth is found in almost every variety of the genus Discorbina .■ but it
may be reduced on the one hand to a mere rudiment, as in the B. r/lobidarls of our own
shores ; whilst, on the other, it may be exuberant enough to form a solid mass, as in the fossil
D. trochidiformis, where we find the surface of that mass covered with hemispherical granules,
which especially run along the margins of the septal junctions, so as to give to tiiis variety
a curious analogical resemblance to Rotalia Beccarii (369).

* This very characteristic figure of the coarsely perforated Discorhina globularis is erroneously
given by Prof. 'Williamson as the young of tlje finely perforated Rotalina (Ptdvintilina) concamerata.

GENUS DISCORBINA. 205

353. This type keeps very strictly, as a rule, to its regular mode of increase ; though
sometimes iu the larger examples of the B. vesicularis we find the spire terminating in a few
irregular or wildly-growing chambers. These may be either unusually large, or may become
suddenly small ; and they may either intercalate themselves along the border of the preceding
segments, or they may grow over the older part of the shell without any definite direction.
The smallest and feeblest varieties of Discorbina form a high cone, which may be flattened
on two surfaces, so as to present a very " textularian " aspect ; on the other hand, the spire
may be so much depressed that the shell comes to have a complanate or even a scale-like form.
It is for the most part in the small complanate varieties that we find an elevation of the
septal bands and of the margin of the spire, which, common as it is in Pidvinulmn, is of rare
occurrence in this group ; of this an example is shown in the Rofaluia ocltracea of Williamson
(ex. Figs. 1 12, 113). One of the most curious modifications of structure in this type consists
in the existence of deep fissures between the successive segments, the walls of which are
complete on either side of these fissures ; as we see in many recent examples of the D. vesicu-
laris of Australia, but still better in the D. rimosa (Parker and Rupert Jones) of the Grignon
Tertiaries and the Australian coral reefs. In this variety we not only find the asterigerine
flaps so much developed as to form a regular series of secondary chambers alternating with
the primary, but we also find the exogenous deposit partially bridging over the superficial
entrance to the interseptal fissures, dividing it into a row of little passages ; and thus is pro-
duced a sort of sketch of that intraseptal system of canals, which we shall see to be more
fully elaborated in Botalia, and to attain its most complete development in Polystonella.

354. Although, as a general rule, the walls of the chambers are coarsely perforated,
yet in some of the smaller and more delicate varieties the pores are very fine. There are
some instances in which a considerable portion of the external surface of each segment ia
destitute of pores, these being limited to the margin, where they are unusually large and
closely set, giving rise to the peculiar appearance represented by Prof Williamson (ex, Figs.
109, 111) as characterising his Hotalina mawilla, a variety of the Rofalia rosacea, D'Orb. In
some varieties these marginal pores are prolonged into short tubes, which give to the edge a
prickly character. The diameter of the shells of this genus ranges from l-6th [D. trockidi-

formis) and l-7th {D. vesicularis) of an inch to as little as l-200th of an inch, which is the
diameter of some of the specimens brought up from the deeper recesses of the ocean.

355. Affinities. — It has been already remarked (^ 341) that all the genera constituting
the proper Bofaline series are intimately connected by mutual affinity; but each of them has
also relations of its own to other types. Thus, as we have seen, the simplest forms oiDiscorbina
connect themselves with Glohir/erina, and even with Textularia ; whilst among its more deve-
loped forms we find approximations to the lower types of the family Nuiiimulinida, the com-
planate varieties reminding us of Operculina, and those in which the " astral lobes' are most
complete bringing us almost into contact with Amphistegina. In general configuration this
genus is closely paralleled by certain forms of the protean arenaceous type Littiola
{\ 213).

356. Geographical and Geological Distribution. — The Rotaline group as a whole may be

206 FAMILY GLOBIGERINIDA.

said to be universally diffused, and to have a very wide bathyraetrical as well as climatic
range. But its several generic forms are by no means equally developed under different
conditions. Thus Discorbina, though presenting itself on the British coasts, in the Mediterra-
nean, and in the East India seas, is there comparatively small ; attaining a much larger size
near the Australian shores. Its most congenial home seems to be in the Algal and Coralline
zone, the deep-water examples of this type being smaller and rarer ; a sandy bottom seems to
suit it best, the specimens found in mud being small and delicate. — These peculiarities of
habit must be taken into account in estimating the geological range of this genus; for it is
quite possible that its absence from all strata in which it has been searched for, earlier than the
Maestricht beds, may be due to the fact that these strata were deposited for the most part in
deep seas. In the Maestricht beds this genus is represented by specimens of medium size ;
its largest fossil forms (which equal or even exceed those found recent on the Australian
coast) are furnished by the Bracklesham and Grignon deposits ; whilst in the later Ter-
tiaries its varieties cloely correspond in size and character with the ordinary existing forms of
the genus.

Ge;;«s XIV.— Planorbulina (Plate XIII, figs. 13—15; and Williamson, Figs. 119—123).

357. External Characters and Internal Structure. — The modification of the ordinary Rotaline
type of which we have next to treat, is one that departs more widely from it in plan of growth
than it does in the character of the individual segments ; these retaining very much of their
simple Globigerine condition, but being disposed in such a manner that their originally
continuous spiral succession gives place to a cyclical arrangement not unlike that of Orbitolites,
whilst this again may give place to an irregular heaping-up or " acervuline" disposition of the
segments. It will be convenient in the first instance to describe a characteristic example of
this type, and then to examine on the one hand the links which connect it with the ordinary
Botulines, and on the other those (so to speak) exaggerated forms by which it comes into
relation with the genera Tlnoporus and Poli/trcma.

358. Such a characteristic example is presented by the Planorhulina mediterranensis
of our own coasts (described and figured by Prof. Williamson, ex, p. 57, Figs. 119, 120),
which attains a considerably larger size in the Mediterranean and in other sub-tropical
and tropical seas, and which has also received the name of P. farcta. The growth
of this shell, which is always attached on one side, commences in a very depressed
rotaline spiral ; the successive segments of which open into one another by a wide
fissure that is close to the inferior lateral surface, which (by the inverted position of the
shell, ^ 345) is here its free surface. After the spiral has made from one and a half
to two turns, however, the segments begin to be added in a manner altogether different ;
the change being made in the first instance by the formation of segments which bud forth
new ones from their peripheral as well as from their umbilical margins ; and from
these a succession of segments is produced, which passes round the original spire, and then
returns into itself. Each of the chambers thus formed has an oval opening at either extremity.

GENUS PLANORBULINA. 207

as is shown in several of the marginal segments of Prof. Williamson's figure (ex, Fig. 120).
From the time that a complete ring of chambers has been thus formed around the original
spiral, the continued growth of this organism takes place upon the cyclical plan ; each new
chamber being formed (as a rule) by a tent of shell thrown over the interspace between two
chambers of the preceding annulus, with each of which it communicates through its oval
aperture ; whilst in its turn it forms two apertures which will communicate with the two
chambers to be formed in alternation with it in the succeeding annulus. Thus in plan of
growth Planorhulina bears a considerable resemblance to that of the simple type of OrhitolUes
(^ 157); but nothing can be more different than the te.xture of the shell in the two cases;
that of Planorbulina being the most coarsely porous of any of the Botalliies (Plate XIII,
fig. 14), so that its animal can send out large pseudopodia from every one of its segments ;
while that of Orbitolites is everywhere unperforated save by the marginal apertures. The
segments of the cyclically growing portion usually elongate themselves in a direction which is
oblique to that of the surface whereon they grow, sloping inwards towards the centre in such
a manner as more or less to cover-in the original spire, which is thus only partially visible on
its free surface, or may even be entirely concealed. The form of the segments is usually more
or less ventricose ; that of the entire shell will vary according to the degree of their oblique
elongation, the centre being depressed when the spiral is merely surrounded by the cyclical
growth, but being elevated when the spiral is covered by the inward extension of the cyclical.

359. Now the spiral plan of growth in which Planorbulina always commences, may con-
tinue without giving place to the cyclical ; and thus are generated three forms, Truncaftdina,
Anomalina, and Planulina, which connect the typical Platiorbulince with the ordinary Rota-
lines. The former of these, TruncafuUna, has ordinarily a plano-convex shell, with a crenulated
margin, and is attached to sea-weeds, zoophytes, shells, &c., by its flat side, on which the
whole spire is apparent ; whilst on its unattached surface, which is really the inferior, the
earher portion of the spire is more or less overgrown by the later (Fig. XXXII, d, e, p. 20).
Its form, however, is liable to very great variation, in accordance with the place and nature
of its attachment, the depth of water, the character of the sea-bottom, and other less de-
finable influences; so that many plates of the great work of Soldani (ci) are devoted to the
figures of the very protean T. variabilis, the ordinary Mediterranean example of this type.
The shell is coarsely porous, and its surface in the older specimens is roughened by minute
tubercles. The apertural fissure, instead of being restricted to the umbilical margin of that
portion of the chamber-wall which forms the septal plane, is usually extended upon tlie inner
margin of the inferior lateral surface, so as to become visible from beneath ; this prolonged
portion of the fissure is not included by the succeeding chamber, and thus it happens that
some of the later chambers continue to retain a direct communication with the exterior ;
this, however, being closed by a subsequent deposit of shell-substance in all the earlier cham-
bers. The shell of Triincatulina may assume the form of a high cone, as in T. rrj'ulgens, a
northern form, of moderate depths, distinguished by its smoothness and polish ; but the real
apex of the spire is still on the flat surface, where the whole spire continues visible. On the
other hand the shell may be extraordinarily flattened, so as to become scale-like and nearly
symmetrical, with squared edges and elevated septal lines, as in the variety described by
D'Orbigny as Plai/uUna Aritnincnsis (Fig. XXXI1,f) ; this presents so close a conformity to

208 FAMILY GLOBIGERINIDA.

the Operculine type as to be readily mistaken for a member of that series, its " truncatuline"
character being only made evident by a comparison of the gradational forms by which it is
connected witli the type. The Trinicatnl'ma of northern seas is seldom observed to present
any more considerable departure from the ordinary Rotaline plan of increase ; but that of
the Mediterranean continually takes on a " wild " growth, its later segments being added
without any regularity, though usually in such a manner as to tend towards a cyclical ar-
rangement ; and specimens of this kind are very commonly found attached to the larger
bivalves (such as P-inna flabellum) in company with PlanorbuUna mediterranensis, exceeding the
latter in size, though not developing nearly as many chambers. In tropical seas the arrested
" truncatuline " forms are rare ; the exuberance of increase manifesting itself very early in
the transition to the " planorbuline '' type, on which a number of new chambers may be
formed at once, instead of in the succession required by the spiral plan.

360. The type which has been distinguished by D'Orbigny as Anomnlina may be de-
scribed as a modified Truncatulina of which the two surfaces are nearly equal, so that the
spire comes to have almost a nautiloid character, and presents a broad sunken umbilicus on
either side. The apertural fissure does not show itself on either surface, being limited to the
septal plane ; but is nearer to the flatter side than to the other. This form may either become
"planorbuline," or may graduate into the "truncatuline;" so that its differential characters
are obviously of no more than varietal importance. One of the forms into which it passes
has been distinguished as F. {Anomatina) coronata ; a variety less common than P. [Truncatu-
lina) lobatula, but abounding in certain localities (as on the coast of Norway and in parts of
the Mediterranean) at depths of 100 fathoms, where it lives independently instead of para-
sitically, developing both its surfaces more or less freely. Both, in older specimens, are over-
laid by an exogenous deposit of clear, non-perforated, shell-substance, which sometimes hides
the septal lines ; but in this there exist lacunce for the exit of the pseudopodia, which seem
especially to extend themselves from the periphery of the chambers ; and these lacunae seem
to prefigure the canal-system which we shall find to constitute a remarkable feature in the
exogenous skeleton of Calcarina.

3G1. It is in tropical regions that PlanorhuUna acquires its largest size and its most
marked development, examples of the parasitic P. vulgaris not uncommonly attaining a
diameter of l-4th of an inch, and presenting such a resemblance to Polyzoa as to be easily
mistaken for members of that group. This augmentation of size partly depends upon the
greater multiplication of segments ; but is partly due to the dimensions which the individual
segments may attain. The early growth of this type (Plate XIII, fig. 13) closely corresponds
with that of P. mediierranensk ; but as its development proceeds we find a remarkable
change in the condition of the apertures of communication between the chambers. These
apertures, which in the Plunorbulino! of temperate seas are never more than faintly lipped,
here become protrusive, each being furnished with a neck and an everted rim. As a general
rule we find the pairs of these necks put forth from two adjacent marginal chambers con-
verging towards each other, both being received into the new chamber which is formed in
alternation with them (fig. 14, «, «) ; and the new segment in its turn puts forth two similar necks
from near its peripheral margin, to be received into two separate chambers of the succeeding

GENUS PLANORBULINA. 209

growth. Sometimes the segments do not come into absolute contact with each other, being
kept somewhat apart by the intervention of the apertural necks ; and each chamber then has
its own complete walls. This varietal modification, however, is much more remarkable in a
])!irasitic form, which has received from Messrs. Parker and Rupert Jones the name of
P. retinaculata ; for the segments are here smaller, whilst the connecting tubuli are relatively
larger and more numerous ; so that the disk is composed of a sort of open network that
spreads over the surface of the shell whereon it grows. Both in this and in the large varieties
of P. vulgaris, the free surface is studded over with large tubercles which arise from it be-
tween the large and sparsely-set pores ; these tubercles are sometimes formed of a remarkably
white opaque kind of shell-substance, giving a very peculiar aspect to the organism (Plate
XII, fig. 15). The Acervulina of Schultzc (.xcvit, p. 67) is nothing else than a Planorbiduia
which attaches itself to the stem of a Zoophyte or some other small rounded body, and of
whicli the segments, instead of spreading discoidally over an expanded surface, cluster
together in a mass, with more or less of regularity of arrangement. Sometimes the mass
acquires considerable compactness from the mutual flattening of the segments against each
other ; and the " acervuline " PlanorbuUiia may thus come to present so close a resemblance
to Tiiiojmrm and Polytremu, as to be almost undistinguishable from those types.

362. JffinUk's. — Besides its affinities to the ordinary Rotalines, and, as we have just seen
to Tinoporus and Polytrema, this genus is related by some of its most symmetrical " anoma-
line" forms to the simpler nautiloid types of the family Ni/mmulinida ; whilst its arrested
" truncatuline" forms are closely paralleled in general configuration by the " placopsiline"
LitiioJcE (t 213). In the cyclical arrangement of its segments of growth, which results from
the mode of increase that may be considered typical of its advanced stage, Plaiwrbulina seems
to conduct us towards PatcUma ; in which we shall find the parallelism to Orbitoliteti most
remarkably carried out.

363. Geographkcd and Geological Distribution. — The conditions which most favour the
production of P/rt//Of(^«///^« seem to be almost exactly the same as those under which i)/.wo?-5///a
most abounds. The numerous specimens which come to us from arctic and temperate seas
are of small size and arrested development ; in both respects the Mediterranean forms of this
genus show a decided advance ; but it is in the tropical and Australian seas that it finds its
congenial home amongst sea-weeds, corallines, and shell-beds, the specimens found at abyssal
depths (1000 fathoms and more) being small and rare.— With respect to the apparent absence
of this genus in the earlier stratified deposits, the remark already made in regard to Discorbiiia
(t 356) equally holds good here ; and it is interesting to observe that although Plaiiorhuliiia
makes its appearance in the Lias, it is represented there by very small forms, such as at
present inhabit great depths ; and that the like condition prevails for the most part in the
Cretaceous formation. In the Tertiary series, however, especially in the Grignon deposits, it
is often very large, although arrested in its development, its forms being identical with such
as now present themselves at depths of from 30 to 100 fathoms.

27

210 FAMILY GLOBIGERINIDA.

Genus XV.— PuLViNULiNA (Plate XIII, figs. 4—6 ; and Williamson, Figs. 98—103).

364. External Characters and Internal Structure. — The group of Rotaline forms wliicli are
associated in this genus consists of those which accord more or less closely with its type, — the
Nautilus repandus of Fichtel and Moll, the Flacentula pulvinata of Lamarck, the RotaUa or
Uotalina repanda of later systematists, — in the freedom of growth and in the fineness of the
porosity of its shell ; by both of which characters, but especially by the second, it is distin-
guished from Discorhbia. The shells of this genus are usually composed of from seven to
twenty-six segments of variable convexity, somewhat loosely aggregated in a depressed
turbinoid spire, so as to have a biconvex form with the upper side thickest, and an angular
or sub-carinate margin (Fig. XXXII, A, p. 201). On the under side there is a large umbilical
space, which may either remain open (ex, Fig. 102), or may be partially or completely filled
by exogenous deposit. The segments usually undergo a rapid elongation ; and sometimes
the later ones spread themselves out irregularly (ex. Figs. 95 — 100). An elongation takes
place in the septal plane, in accordance with the extension of the chambers ; and in such
cases it tends to become flattened (ex, Fig. 95), and is very commonly punched with large
" orbuline" foramina. The aperture is usually a large slit at the base of tlie umbilical margin
of the septal plane ; and is frequently still further enlarged by irregular deficiencies at its
septal edge. In the typical Puhinulincs the exogenous deposit is chiefly confined to the septal
bands, which it often raises into ridges so as to produce a strong " limbation ;" but it may
also roughen the general surface with minute granulations. Some of the most oblong-
varieties, as the Eolalina ohlonya of Williamson (ex, p. 51) were included by D'Orbigny in
his genus Valvulina.

365. The expanded form of this type may give place to one more contracted, in which
the segments are more compactly arranged, so as to produce by their aggregation a thick
conical shell, of which the external walls are " flush." In this variety the upper surface
usually receives a considerable amount of exogenous deposit, which forms a strong " limbation"
on the septal lines (ox, Figs. 101, 103), and covers the outer walls of the chambers with
large closely-set granules ; and the aperture passes into the condition of a notch. Tlie limba-
tion and granulation attain their maximum in the conus-shaped P. caracolla of the Oolite,
Gault, and Chalk-marl, in which the limbation is stronger than in any other Rotalines, the
faces of the chambers often lying deep between wall-like ridges both above and below. The
variety known as Botalia Ilenardii is a common deep-sea form of PidvinuUna, flattish, limbate,
and granular ; and tliis is sometimes accompanied by the E. elegans vel PartscMana (lxxiii),
a large flush-chambered shell, with a prominent umbo formed by a mass of exogenous deposit,
which variety ranges also into shallower water. In some other varieties allied to B. Menardii
the hmbation is wanting; the septal bands being flush with the surface, or being even furrowed.
In the P. Schreibersii and allied varieties the limbation is but faint, or is altogether wanting,
on the upper surface of the shell; whilst on the under surface there is a strong astral
limbation proceeding from the exogenous deposit which occupies the umbilical vestibule.

GENUS PULVINULINA. 211

366. The characteristic form of PuJvimdina is subject in the Laminarian zone of warmer
latitudes to a modification so remarkable, that its Rotaline character would scarcely be recog-
nisable if its affinity were not traceable through intermediate gradations. This form (Plate
XIII, figs. 4 — 6) has been described by D'Orbigny under the designation PlanorbuUna
vermiculata ; but although to a certain extent analogous to PlanorbuUna in its plan of
growth, it differs from it entirely in other characters, and can be readily shown to be essen-
tially a PidvinuJina extremely flattened-out, of which the later chambers elongate themselves
like the continuous tube of a Spirillina, with very few interposed septa, sometimes returning
into themselves so as to form complete though irregular annuH, of which the earlier are
surrounded by the later. The substance of the shell in this curious variety is very finely
porous, the pores being grouped in little bundles (fig. 6), and sometimes looks almost horny
in its transparency and hue ; but on its attached surface (fig. 5) we notice that it is (as it
were) punched-through with large irregularly scattered apertures. These expanded forms
sometimes attain a diameter of l-7th of an inch j on the other hand, the contracted
deep-sea forms have no greater a diameter than 1-2 50th of an inch. The diameter of the
ordinary trochoid forms of moderately deep water ranges from about 1 -20th to 1 -50th of an
inch.

367. Affinities. — This genus holds among Rotalines, in regard to the fineness of the
texture of its shell, and the freedom of its mode of growth, a rank analogous to that of
Bdimi/ia in the Textularine series. Its nearest affinity, however, out of its own sub-family, is
to SpiriUina, to which its lowest forms approximate closely in mode of growth ; whilst the large
pores that are met with in the chamber-walls, not only in these but in higher forms, mark the
persistence of an Orbuline condition of the animal. In this genus, moreover, as in the two
preceding, we find complanate nearly symmetrical varieties with raised edges, that bear a
strong resemblance to OpercidincB.

368. Geographical and Geolocjiral Bistrihdion. — The conditions under which this genus
flourishes best are by no means the same as those which most favour the development of the
two preceding types ; for some of the largest examples of Pidvinulina come to us from within
the Arctic Circle, and plenty of good-sized specimens may be obtained from extreme depths.
The examples which occur in the Algal zone, on the other hand, are for the most part the
feeblest. It is, perhaps, on account of its prevalence at greater depths, that this type has
been distinctly recognised at an earlier geological period than any other of the Rotalines ; the
P. elegans having been found so abundantly in the Upper Triassic clay of Chellaston by
Messrs. Rupert Jones and Parker (lv), as to constitute nearly one-half of the Foraminifera in
which that deposit is rich. The genus continues to present itself in the Liassic and Oolitic
series, its examples being generally small but strongly limbate ; in the Gault their size
increases, the limbation being still very strong ; and they become still larger in the Chalk-
marl. It is very probable that these diversities have reference only to the depths at which
the clay-beds that have been hitherto examined in these formations were respectively depo-
sited. The highest development of this genus seems to have been in the Tertiary series, and
especially in the Crag-formation.

212 FAMILY GLOBIGERINIDA.

Gejius XVI.— RoTALiA (Plate XIII, figs. 7—9; Williamson, Figs. 90—92, 106—108).

369. External Characters. — It is in the true RofalicB, of which R. Beccarii is the typical
example, that we meet with the highest development of the Rotaline type, and the nearest
approximation to the Nummuline. This approximation is shown in its shell-substance, which
is of unusually fine texture, its pores being as minute and as closely set as they are in Opercu-
lina or Nummdina (Plate XIII, fig. 8). It is further marked in the general compactness of
the shell, and in the mode in which it is strengthened and completed by an " intermediate
skeleton." But it is especially manifested in this important feature, — that every ciiamber is
completely surrounded by its own proper wall, no part of its boundary being borrowed from
that which belongs to the penultimate segment. Hence every septum dividing adjacent
segments is double instead of single ; and its substance rather resembles that of the interme-
diate skeleton than that of the ordinary chamber-wall, being entirely destitute of the minute
porosity which characterises the latter. In this respect, therefore, there is an important
advance in that development which consists in progressive differentiation. In the ordinary
British form of P. Beccarii, which is accurately described and figured by Prof Williamson
(ex, p. 49, Figs. 90 — 92), the shell has a rather depressed turbinoid form, with a
rounded margin ; and is composed of a considerable number of segments progressively
increasing in size, disposed with great regularity, and having their apposed surfaces
closely fitted to each other. The whole of the spire from its commencement is visible on the
upper surface ; whilst on the lower only the last convolution shows itself, the segments being
arranged around a deep umbilical vestibule, which is filled up with a column of homogeneous
semi-crystalline shell-substance. This column sometimes projects as an umbo from the
surface, and is clustered over with granulations and incrustations of the like material; similar
granulations extend along the umbilical margins of the segments, which are frequently a good
deal separated from each other, the intermediate spaces being sometimes filled up with tiic
semi-crystalline substance resembling that of the umbilical column. Owing to the somewhat
ventricose form of the segments, their lines of junction along the whole spire would be deeply
furrowed, were it not that the depressions are partly filled up by deposits of the like substance,
which strongly mark the septal lines by the difference of their aspect from that of the inter-
vening porous chamber-walls. The septal plane is distinguished by its translucency ; and the
aperture is usually a neat arched slit, which is much more nearly medial than in the Rotalincs
generally, being very little beneath the contiguous peripheral margin of the penultimate
convolution'. In some varieties, however, the aperture has a notch in the umbilical margin of
the septal plane. The diameter of this shell, which is an inhabitant of moderately deep
water, is usually from l-2.5th to l-30tli of an inch.

370. A feeble shallow-water or littoral variety of this type has been described and figured
by Prof. Williamson (ex, p. 54, Figs. 106 — 108) under the designation R. uifida ; here the
segments become quite " flush," so that the surface of the cone is smooth ; the walls of the
chambers are very thin and translucent, and there is but very little exogenous deposit either
along the septal bands or in the umbilical vestibule. A like deficiency of exogenous deposit
is observable in the large smooth R. ammonifornm (D'Orb.) of the Rimini shore, which lias

GENUS ROTALIA. 213

the umbilicus open, as in the recent feeble forms. In the strongest tropical forms of moderately
shallow water, on the other liand, of which the R. Sckroeteriana (erroneously designated
Faujasina by Prof. Williamson cix) is a characteristic example, the form of tiie shell is com-
pletely changed, by the peculiar form and disposition of the segments, from that of a Turbo
to that of a Conus ; the upper surface being now flat or nearly so, whilst the lower surface
becomes conical (Plate XIII, fig. 7). Notwithstanding this striking metamorphosis, the
essential identity of the two types is proved by the cxistenL^. of a complete series of grada-
tional links between them, some of these intermediate forms being almost equally conical
on the two sides, but showing the whole spire on one lateral face, whilst only the last
convolution is seen on the other. In the typical R. Sckroeteriana, which attains a
diameter of l-12th of an inch, the upper surface is rendered " limbate" by the prominence
of the septal bands, which are ornamented with rows of hyaline tubercles; and these tubercles
are continued along the septal bands down the side of the cone, until they join a large irre-
gular mass of the same semicrystalline substance tliat occupies the apex of the cone, which is
here tlie real umbilicus of the spire. Between these tubercles there may be distinguished, under
a sufficient magnifying power, a single or double row of large pores along each septal band.
The aperture has more or less of an oval form, and is usually situated about half-way between
the upper flat surface and the umbilical prominence. In a remarkable variety of this type
from the Fiji islands, the spire is more symmetrical, and the aperture is bridged over by trans-
verse bars (as in Calcariiia), so that the shell becomes almost isomorphic with Pohjdomella
craticidata ; to which type it further bears considerable resemblance in the disposition of the
exogenous deposit, and in the mode in which the intraseptal passages open on the surface
along the septal bands (§ 372.)

371. Various weaker modifications of the preceding forms present themselves at different
depths in the tropical ocean and in marine deposits of different geological ages. Thus, from
100 fathoms and more we have recent examples of the R. Soldanii of the Vienna Tertiaries
(lxxiii), which is identical with the R. lunhilicata of the Chalk ; a close thickset smooth
form, without septal granulations, and having its umbilicus sometimes occupied by a single
large rounded tubercle. Again the R. orbicularis (which ranks as GyroidiiKi in D'Orbigny's
models) is almost hemispherical in form, its chambers being quite " flush," and its upper flat
surface showing the entire series, which consists of about forty segments, whilst its lower
spherical surface shows ten or twelve. A still more marked departure from the typical form
is produced by the extension of three or four of the septal bands of the first convolution into
long smooth radii, giving rise to the variety described by D'Orbigny as Cah-uriaa jjitlchella,
which is further remarkable as having each of its raised septal bands double. And finally,
in a conus-shaped tropical variet)', which has received from D'Orbigny the names Antcrii/criiui
carinala and A. lobafa, the umbilical lobes of the chambers are separated from the principals
by the intervention of a septum, so as to constitute a secondary series of chamberlcts which
interdigitate or dovetail themselves between the proper chambers, as do those of the lower
surface of Ampliistefjina vuhjuris and its varieties (Plate XIII, fig. 23), instead of lying in a
lower plane like the subsidiary chambers formed by astral flaps in Divcorbiiia (^ 352).

372. Internal Structure. — The internal structure of the most developed form of the genus

214 FAMILY GLOBIGERINIDA.

Rotalia has been very accurately described by Prof. Williamson (cix), whose account of it is
confirmed in every particular by my own inquiries. When a horizontal section is taken near
the upper or flat surface of the shell, the whole spire is laid open, as shown in Plate XIII,
fig. 8 ; the finely-tubular structure of the lateral walls of its chambers, and the absence of
tubuli from the intervening septa, are apparent ; while a marked peculiarity here presents
itself in the septa being composed of two lamellae, between which there is sometimes a con-
siderable interspace. The intraseptal spaces are connected into a system of passages which
extends in a radial direction from the centre towards the periphery ; each passage first tra-
versing one of the intraseptal spaces, and then usually bifurcating as it enters the spiral lamina,
its two branches divaricating in such a manner as to pass to two septa in the next convolu-
tion. By comparing this, however, with such a vertical section as is shown in Plate XIII,
fig. 9, it is made apparent that what seem to be canals between the septa are in reality the
lower edges of intraseptal /55?«-e5, which intervene between the two lamellae through nearly
the whole area of each septal plane. From that edge of each fissure which is nearest the flat
surface, passages are given off which run towards that surface to open between the tubercles
on its septal bands ; whilst from that edge of the intraseptal fissure which abuts on the
oblique side of the cone, there is given forth a row of passages which open along the septal
band that passes vertically towards the umbilicus. Before reaching the surface these passages
usually divaricate, and the wedge-like space between each bifurcation (fig. 8, a) is occupied
by non-tubular substance, which forms, in fact, the base of one of the tubercles that rises
from the septal band. The exogenous deposit of which these tubercles are formed, extends
over the whole surface of the shell, adding considerably to the original thickness of the
walls of the chambers. It is shown by the vertical section (fig. 9) how the peculiar form
of the shell is engendered by the remarkable elongation of the later chambers between the
lateral surfaces, so that the upper side of each succeeding whorl is kept on a level with the
preceding whorl above, whilst it is produced far beyond it beloio. This production of each
whorl leaves a large umbilical fossa of irregular form, which is filled up with homogeneous
shell-substance, so as to become a sort of columella.

373. Affinities. — The very marked participation in certain characters of the Nummuline
series which is exhibited by this genus, would suiBce, if taken by itself, to justify its claim to a
place among them ; the relationship of its most developed forms to those of PohjsiomeUa in
particular being so intimate, that the two cannot be justly considered as far removed from
each other. But, on the other hand, the general affinity of Bolnlia, to the other genera of the
Rotaline series is so close, that it is quite impossible to detach it from them ; and it must be
regarded, therefore, as the link which establishes the transition between the ordinary Rotaline
and the Nummuline series. It is impossible, moreover, not to be struck with the analogical
relationship between Roialina and Carpenteria, which hold the highest places in their respec-
tive series ; for Carpenteria would in all essential particulars be an outspread Rotalia attached
by its upper lateral surface, if its chambers communicated with one another, instead of open-
ing separately into a common vestibule.

374. GeograpJdcal and Geolofjical Distribution. — The true RotaHa may be considered as
essentially a sub-tropical form ; its characteristic features being well exhibited in specimens

GENUS CYMBALOPORA. 215

from the Levant. It has not yet been found in the Arctic seas, and it is neither abundant
nor of more than half its ordinary size on the British coasts ; on the other hand, it is in tropical
specimens that we find it most thickly clothed with exogenous deposit, and its canal system
most developed. It does not flourish in deep waters, its size being reduced to less than one
fourth at a depth of 100 fathoms ; whilst its form is altogether changed, and it becomes very'
small and rare, at 1000 fathoms. On the other hand, it extends far up estuaries and into
salt-bogs — No true Rofaliie are at present known to have existed earlier than the Chalk, in
which formation there occur examples of B. Bcccarli whose small size indicates that they
lived at considerable depths, probably from 100 to 400 fathoms. It is in the Tertiary forma-
tions, however, that this sub-genus occurs in greatest abundance ; some shallow water-beds
of the Crag and of the Siennese deposits being almost entirely composed of Bolalice.

Genus XVII.— Cymbalopora (Plate XIII, figs. 10—12).

375. External Characters and Internal Structure. — This small genus,including only four spe-
cific forms hitherto described, was instituted in 1850 by Hagenow (" Die Bryozoen der Maas-
trichter Kreide-bildung") on the basis of a minute fossil which he supposed to be a Bryozoon,
but which has been found by Messrs. Parker and llupert Jones to agree in structure with
the Bosalina Poei/i of D'Orbigny (xcii), a type distinguished by peculiarities of conformation
quite sufficient to differentiate it from all other genera of the Rotaline sub-family. All the
examples of this genus are of comparatively small size ; the diameter of the largest of them (fossil
from the Upper Chalk of Maestricht) being not more than l-18th of an inch ; whilst that of
the ordinary specimens obtained from deep water at the present time does not exceed l-120th
of an inch. When seen from the superior lateral surface, or looked at edgeways (Plate
XIII, fig. 10), a Cymbalopora does not present any marked feature that distinguishes it from a
trochoid Biscorhina, save that the spiral arrangement of its segments does not appear to be
continued with regularity as the cone enlarges. But when its inferior surface is examined, a
very extraordinary departure from that regularity displays itself; for we there find its seg-
ments arranged concentrically around a deep umbilical vestibule, which extends far up into
the cone. Sometimes these segments are numerous and narrow, and being as it were
wedged in between the segments of the preceding layer, they are separated from each other
by considerable intervals (Plate XIII, fig. 11). But in other cases they are few in number
(the whole annulus being made up of only four or five), broad, and flat ; and the interval between
them is reduced to a flssure (fig. 12). In either case each segment communicates with the
umbilical vestibule by a prolonged tubular neck ; and it also has two large lipped orifices on
either side, apparently for the passage of sarcode-stolons to the adjacent segments. Tl>e
shelly lamina which forms the basal walls of these segments is much more hyaline and less
porous than that which bounds them externally ; and we notice the homologue of the asteri-
gerine flaps of Discorhina in the frequent extension of a lamella of shell over the umbilicus,
closing-in its cavity, and connecting together the internal necks of the segments. It can
scarcely be doubted that this umbilical cavity is occupied in the hving condition by a portion
of the sarcode body of the animal ; and that from this are put forth by gemmation the seg-

216 FAMILY GLOBIGERINIDA.

ments that form each new annulus of chambers, since the chambers of one annulus have no
direct communication with those of the annulus which preceded it. In this respect, there-
fore, we have a curious analogy to Dactyhpora, in which, however, the independence of the
segments is greater, no communication existing between even those of the same annulus
(f 190).

376. The mode in which the spiral growth is exchanged for the concentric seems to be
essentially the same with that in which it is accomplished in PlanorbuJum (f 358) ; the spire
first becoming excentric by the development of new chambers on one side onl}^ (in such a
manner that the primordial segment seldom lies at the apex of the cone, but a Httle on one side
of it), and being then inclosed by an annulus formed by the gemmation of new segm.ents. In
Pla7iorhidt7Ui, however, each successive annulus is formed around the margin of the preceding,
from which every one of its segments derives stolon-processes ; whilst in Ci/iiibnlajjora each
new annulus is formed beneath the preceding, and has apparently no direct derivation from it.
The principal departure from the typical form is shown in the C. buUoides (Bosalina bulloides,
D'Orbigny, xcii). in which the whole of the base is occupied by a single large chamber, the
wall of which, instead of being furnished with its normal apertures, is perforated by numerous
large 'orbuline' lipped pores.

377. Ajjiiiiiies:. — In the character and disposition of its earlier segments, and in the
asterigerine lamella at the base of its cone, Cymbcdopora ma}^ be considered as most nearly
related to Biscorbina ; but in the exchange of the spiral for the cyclical plan of growth, it
accords with Planorbnlina, differing from the last-named genus, however, far more than the
"wildest" of those forms to which we have extended its designation.

378. Geographical and Geological Distribution. — The little Cgnibalopora is at present
restricted to the warmest seas, not being found in the Mediterranean, but being common in
the Ked Sea, in the East and West Indian Seas, and on the shores of the Fiji and other
Polynesian islands and of Australia. It frequents the Algal and Coralline zones and shell-
beds; and becomes small and irregular when presenting itself (as it not rarely does) at
depths of 500 fathoms. The only occurrence of this genus in a fossil form is in the
Maestricht beds, in which it presents itself in association with Calcarina and Biscorbina. Its
absence in the Tertiary strata of Europe (so far as is yet known) taken in connection
with the essentially tropical habitat of its recent representatives, is a fact of some
significance.

Genus XVIII.— Calcarina (Plate XIII, fig. 21 ; Plate XIV, figs. 1—10).

379. External Characters. — The name bestowed on this genus, of which the C. Spengleri
(the Nuutilm Spengleri of Linnaeus) is the typical form, is derived from the resemblance which
it presents in general aspect to the rowel of a spur (Plate XIV, figs. 1, 2), this resemblance
being produced by the divergence from the central disk of a set of rays or spines, which vary

GENUS CALCARINA.

217

Fig. XXXIII.

alike in number, length, and direction. These spines are usually few in young specimens, and
become numerous with age ; but this rule is by no means constant, since full-grown
specimens are occasionally met with having no more than four or five very short spines
(Fig. XXXV, h). The spines are usually either cylindrical or somewhat club-shaped, the latter
form being the more common ; but we occasionally see them showing a tendency to bifurcation
or trifurcation at their extremities ; and they not unfrequently appear as if two, three, or even
four spines had coalesced to form one, — this being indi-
cated not only by its unusual size, but by the mutual di-
vergence of its components as they extend themselves
from the central disk (Fig. XXXIII, b, and Fig. XXXIV,
f). a somewhat remarkable contrast in the relative
development of the disk and of the spines is presented
by the general aggregate of the specimens obtained
from the Philippines and the Mediterranean respectively ;
as is shown in comparing Figs. XXXIV and XXXV.
It is in the former that we meet with the greatest num-
ber as well as the greatest relative length of the spines ;
and that the bifurcation or trifurcation of their extre-
mities presents itself. In full-grown specimens of the Philippine Cdcarina, we com-
monly find the spines diverging from the margin of the central disk in such abundance.
Fig. XXXIV. Fir. XXXV.

Two specimens of Philippine variety of Cul-
carina, distinguished bj unusual exuberance of
spinous outgrowths.

Outline-representations of various specimens of
Philippine variety of Calcarina.

Outline-representations of various specimens of
Mediterranean variety of Calcarina.

that very little of that margin is left free. The length of their spines, moreover, at
different ages, varies pretty constantly with the diameter of the disk, the average pro-

28

218 FAMILY GLOBIGERINIDA.

portion being about two-thirds ; though we occasionally meet with specimens in which the
disk is unusually large and the length of the spines does not equal more than half its
diameter, and others in which the disk is unusually small and the length of the spines is
equal to its whole width. In the Mediterranean Calcarina, on the other hand, I have
seldom met with more than nine spines ; and any excess beyond that number is only
presented by specimens in which the disk is very large, so that wide intervals present them-
selves along its margin between the bases of the spines. Their spines are nearly always
simply clavate in form, any tendency to bifurcation or trifurcation at their extremities being
rare ; and they show but little disposition to increase in length with the enlargement of the
central disk, being often not only relatively but even absolutely shorter in old specimens ; as
if the spines had entirely ceased to grow, and the disk had (as it were) included their basal
portions within itself. In some instances, indeed, they scarcely show themselves enough to
attract attention ; being little more than tubercular projections from the margin of the disk
(Fig. XXXV, h). Notwithstanding, however, this strongly marked difference in general
physiognomy, it becomes obvious, on the comparison of a sufficient number of individuals, that
no line of specific distinction can be fairly drawn on such a basis between the Philippine and
the Mediterranean forms ; since among the Philippine we meet with numerous specimens in
which the spines are as few and simple as they are in the great bulk of the Mediterranean
(Fig. XXXIV, B, c) ; while specimens not unfrequently present themselves among the
Mediterranean, in which there is not merely an addition to the ordinary number of the
spines, but a manifest disposition in many of them to subdivide near their extremities, thus
showing an obvious approximation to the Philippine type. Although the spines usually
radiate nearly in the equatorial plane, yet it becomes obvious, when their connexion with the
central disk is examined, that they originate at different levels (Fig. XXXV, e, f) ; this will
presently be found to depend on the turbinoid form of the spire (^ 383). Besides
the ordinary radiating spines, an extraordinary growth of short pointed spines is sometimes
seen, either partially or completely covering one or both surfaces of the central disk (Fig.
XXXIV, g) ; and examples occasionally present themselves (Fig. XXXIII, a), in which
the development of these seems to have altogether superseded that of the ordinary radiating
spines.

380. It is remarkable that among the very young specimens of this type, a yet greater
variety shows itself than among those further advanced in life. At Fig. XXXIV, a, b, c, is
shown what may be considered the ordinary or normal aspect of the young Calcarina ; whilst
in Plate XIV, figs. 6, 7, we have a representation (under higher magnifying powers) of an
example of what may be termed the hispid condition, which so frequently presents itself in
small CalcarincE as to give rise to a question whether they should not be made to constitute a
distinct species. I have satisfied myself, however, by the comparison of a large number of
specimens, that so continuous a gradation presents itself between the smoothest and the most
hispid specimens, as to render the attempt to separate them specifically altogether futile; and
Mr. Parker, who has examined a yet larger number of specimens, fully confirms this con-
clusion. Moreover, the internal structure of these hispid specimens shows no departure
whatever from the ordinary type.

GENUS CALCARINA. 219

381. Returning, now, to the external aspect of the fully-developed Calcarina, we have to
notice that each surface of the disk is very commonly elevated, especially in its central
portion, into rounded tubercles, more or less closely set together (Plate XIV, fig. 1). Tiiese
are sometimes large and prominent, and present the semi-transparent appearance which is
common among the like tubercles of Operculina (IT 436) ; more commonly, however, they are
less conspicuous either as to size, prominence, or distinctive aspect ; and sometimes they are
almost or altogether wanting (fig. 2). Yet it is seldom, if ever, that they are absent from
both surfaces of the disk ; and it is more common to find them deficient on the surface
nearest to the apex of the spire, than on that on which its last-formed chambers are visible.
And even when no prominent tubercles are present, a distinction may be generally made out
by careful examination in the parts of the surface corresponding to tlieir usual situation.
For whilst the exterior of the disk is marked, more or less conspicuously, with minute
punctations (fig. 8), these are not to be seen on its tuberculated prominences ; and the like
deficiency is generally to be noted in circular spots of the surface, even when it is not raised
into tubercles. Occasionally, though rarely, not even this mark of differentiation is seen, the
punctations being uniformly distributed over the surface, which is in that case always the
one nearest the apex of the spire. Tiie surface of the spines is marked, more or less
conspicuously, by a longitudinal furrowing (fig. 8), not unlike that of the "marginal cord" of
Operculina (^ 444). The furrows maintain a general parallelism, but there are frequent
inosculations between them ; and punctations marking the orifices of deeper canals are
often to be noticed at the bottom of the furrows. On one of the surfaces of the disk the
indication of a sj)ire is more or less distinctly observable (Plate XIV, fig. 1) ; also
(Fig. XXXIV, B, Fig. XXXV, d, g, h). This indication is sometimes limited to two or three
chambers ; but more commonly about half a turn may be distinguished, the spire becoming
absorbed (as it were) into the solid mass of the disk, as we trace it backwards. The walls of
the last-formed chambers, where entirely disengaged from the disk, are extremely thin
(Plate XIV, fig. 8, b, b), so that it is rare to find them perfect ; and an opening formed by the
fracture of the wall of the newest chamber has been mistaken by Fichtel and Moll, and appa-
rently by D'Orbigny also, for the true aperture of the shell, which, as will presently appear, is
of an entirely different character, and is not easily to be distinguished. The prominent surface
of the walls of the conspicuous chambers of the newest whorl is covered with punctations
resembling those of the general surface of the disk ; but they are more minute and more
closely set together, and they are distributed with great uniformity, no unpunctated spaces
being anywhere visible.

382. Internal Structure — When the internal structure of this organism is examined by
means of thin sections taken in different directions, the apj^arent anomalies of its conformation
are found to be dependent simply upon the extraordinary development of its " supplemental
skeleton ;" its general plan of structure being much simpler than the peculiarities of its aspect
would seem to indicate. The spire, as laid open by vertical section (Plate XIV, fig. 3), is
turbinoid ; consisting usually of about five whorls {a, a^, a~, c?, a^), that start as usual from
a central cell, and progressively increase in size ; each whorl is applied merely to the
surface of the preceding, and does not invest it in any degree, the chambers being altogether
destitute of alar prolongations. The aspect of the spire as seen in equatorial section is

220 FAMILY GLOBIGERINIDA.

shown in fig. 4 ; this section, being taken in such a plane as to cut through the outer whorls
<•/*, (f, a", passes entirely over the surface of the two inner whorls a^ and a. The disposition of
the chambers, as indicated by such sections, is ideally shown in fig. 8. The turns of the
spire are separated from each other by the interposition of a thick layer of solid shell-sul)stance;
and this is quite distinct from the proper walls of the chambers, as is well seen in fig. 4,
where the walls, b, of the newest chambers are shown to be entirely destitute of any such
addition, whilst in the preceding part of the same whorl we observe them encrusted by a thin
additional layer d, and as we trace this layer backwards to d^ and r/", we perceive that it pro-
gressively augments in thickness, until it acquires its maximum at d^, just where it is covered
by the subsequent whorl. This distinction between the proper walls of the chambers and
the " supplemental skeleton" can be traced to the very centre of the spire. The septa are
entirely formed by the infolding of the proper walls of the chambers, which at their planes of
junction are destitute of the pores with which their substance is elsewhere minutely
penetrated ; sometimes the septum consists throughout of only a single lamella, as in Discor-
bina ; but most commonly it is composed at its outer part of two lamelte, which, though
usually in contact, sometimes diverge to give passage to canals ; whilst sometimes it is double
throughout. There does not appear, however, to be any regular " interseptal system" as in
Operculina and Polysiomella. The communication between the adjacent chambers of the same
whorl is efi'ected, as in Polj/sfomella, through a series of pores (fig. 3, c) disposed at pretty
regular intervals along the inner margin of the septum ; these may be considered as formed
by the bi'idging over of an elongated fissure by delicate bars of shell-substance. The
external aperture of course presents the same character (fig. 8, c).

383. That the spines entirely originate from, and are strictly appendages of, the
" supplemental skeleton" is well seen in fig. 4, which shows their connexion with its
successive convolutions. Thus the spine / is one of the oldest, being traceable inwards to
the earlier whorls ; whilst those marked /\ /", /'\ f\f^ are obviously of progressively later
production, their respective origins being further and further removed from the centre of
the spire. It is, moreover, to be observed that each spine receives an augmentation in
thickness as the convolution from which it sprang is encircled by others ; this augmen-
tation, however, is not marked (as in the spines of Echini) by lines of demarcation between
the earlier and the later formations ; and there is every reason to believe that the
growth of the spines, both in length and in diameter, is continuous rather than interrupted.
Although it might seem, from the examination of such sections only as are taken in the
direction of the equatorial plane or in one parallel to it, as if the course of the spire must be
seriously interrupted by the radiation of the spines (which sometimes appear to be so
interposed between consecutive chambers as completely to separate them), yet the fact is that
owing to the turbinoid form of the spire, a spine projecting from an earlier whorl is very
little in the way of even the next convolution ; for as this passes by the spine on a difi'erent
level, its chambers are but slightly encroached-on, and this only upon the side which looks
towards the apex of the spire, — as will be readily understood by examining the relation of
tiie last half-convolution, visible in such a specimen as the one delineated in Plate XIV, fig. 1,
to the pre-formed spines, or by an inspection of the ideal represented in fig. 8,

GENUS CALCARINA. 221

384. The canal-system of Calcarina presents a development so extraordinary in itself,
and so obviously related to that of the " supplemental skeleton," as to throw great light upon its
special functional destination. We do not here observe any such peculiar but limited distri-
bution of systematically arranged passages, as that which constitutes so remarkable a feature
in Polystomella ; but every portion of the supplemental skeleton, with the exception of certain
solid cones presently to be noticed, is traversed by canals which run very close together,
with frequent inosculations, and which thus form a continuous network with long narrow
meshes, that commences from the parietes of the chambers and extends itself to the very
extremities of the spines (figs. 3, 4, 8). The proper walls of the chambers, as already stated, are
uniformly perforated, like those of the chambers of Discorbina, by foramina of considerable size
(averaging about 1 -3000th of an inch in diameter) ; with these the canals of the supplemental
skeleton do not seem to be directly continuous, for they are of about double the diameter and
lie further apart from one another ; but immediately round the proper walls of the chambers
(as shown in fig. 3) there seem to be irregular lacunar spaces, into which their foramina open
externally, and from which the passages of the canal-systern originate. How numerous and
closely-set these passages are, is shown in fig. 9, which is taken (under a much higher
magnifying power than the rest of the figures) from a section that passes through the
supplemental skeleton just outside the walls of one of the chambers, in such a direction as to
cut through the passages transversely or obliquely. These passages run in different
directions ; some proceeding directly towards the external margin of the convolution, and
being continued into the spines where these are given off from it ; whilst others pass not less
directly towards the two convex surfaces of the disk. In the earlier whorls of the spire, as
shown at fig. 4, a, indications of spiral canals, commencing (as in Poli/stomella, ^ 478) in a
central lacunar system, are frequently traceable ; and sometimes we may make out a general
distribution of the canal-system of the earlier whorls, that strongly reminds us of that which
prevails in Polystomella (^477), the canals of the spines originating (as seen at a) in diverging
branches which radiate outwards through spaces left between the two layers of the earlier
septa. But this arrangement soon seems to be merged, as it were, in the much more copious
distribution of passages that arise from the lacunae round the proper walls of the chambers.
The canals which pass towards the tw,o lateral surfaces soon lose the general uniformity of
arrangement which they elsewhere present; for they become crowded together in some situa-
tions and separated in others, so as to leave a number of columnar spaces untraversed, whilst
the intercolumnar spaces are copiously penetrated by them, — as is seen at e, e, e, in figs. 3
and 10, the former showing the solid columns divided longitudinally, and the latter showing
them as they are cut transversely. The varying appearances of the external surface, as
described in 1 381, will now be understood. When, as commonly happens, the summits of
the columns rise above the general level of the surface, they will show themselves as rounded
tubercles. But when they are not thus elevated, they will merely be distinguished as circular
spots surrounded by the punctations which are the orifices of the canals. In the spines, on
the other hand, the canals form a longitudinally inosculating system (figs. 4, S), of which the
branches near the surface usually reach it so obliquely as to pass along it for some distance
as open furrows, the punctations seen in which are the orifices of branches that strike
the surface at a greater angle.

222 FAMILY GLOBIGERINIDA.

385. It is obvious from the foregoing description, tliat the nutrition of the spines must
be provided for either through the investment of their surface by external prolongations of
the sarcode-body, or through the penetration of its substance by prolongations of the sarcode-
body conveyed into it by the canal-system, or through both methods jointly. That the sarcode-
body is continued in the form of pseudopodial prolongations into the canal-system can scarcely
be doubted, when it is borne in mind that such prolongations are known to pass through the pores
which are scattered through the chamber- walls oi Rofalia, and to extend themselves through the
surrounding medium. After having made their way through the proper walls of the chambers
of Calcarina, they will probably coalesce again in the lacunar cavities on the exterior of these,
just as they coalesce to form a continuous layer of sarcode over the chamber-walls of Rotalice
or Polydomellce ; and from the aggregation of sarcode in those cavities a new set of pseudo-
podial prolongations will take their departure through the canal-system of the " supplemental
skeleton," just as a secondary set of pseudopodial filaments of sarcode are often seen to
diverge from the little agglomerations formed by the reunion of some of those that primarily
issue from the pores of the shell (1^33). The analogy of other Foraminifera, moreover, renders
it very probable that the prolongations of the sarcode-body which reach the surface through
the canal-system, will reunite upon it so as to form a continuous investment over the whole ;
and that this will be especially the case on the spines, appears to be indicated by the provi-
sion there is in the furrowing of the surface, for conveying the prolongations of the sarcode-
body to every portion of their exterior.

386. One more fact remains to be noticed, which is of much interest as showing that
the growth of the spire and that of the " supplemental skeleton" are to a certain extent inde-
pendent of each other : — I refer to the departure from the regular form that frequently shows
itself in the later turns of the spire, which (so to speak) often " run wild" in a variety of
strange modes, examples of which are so well represented in Fig. XXXIII, a — f, that it is

Fig. XXXVI.

Abnormal specimens of Calcarina.

unnecessary to refer to them in other than these general terms. The extension of spines
from the whole surface of the disk, in the mode represented in Fig. XXXIII, A, may in like
manner be regarded as a sort of " running wild" of the supplemental skeleton.

GENUS TINOPORUS. 223

387. Varieties. — The highly developed type which is now being described, is subject to
considerable modification in feebler forms. One of these, the C. culcar of D'Orbigny (xcii), is
remarkable for the radiating prolongations of the chambers themselves (Plate XIII, fig. 21),
every one of which is ensheathed by a layer of exogenous substance that extends itself to form
the points of the ray.

388. AJJinities — Although I consider the difference of aperture, with the extraordinary
development of the supplemental skeleton and its canal-system, as sufficient, when taken
together, to give to Calcarina a title to distinct generic rank, yet there can be no question of
its extremely close relationship to liotalia. The arrangement of the chambers is in all
essential particulars the same as that which is characteristic of that genus ; and the
subdivision of the fissured aperture of the Itofalina into a row of pores is no greater a
difference than that which we shall find to exist between the " nonionine" and the typical Polj/-
sfomella, being moreover absent in some feeble CalcarincB, whilst it presents itself in a variety
of the true Eofalia. In certain forms of Ttotalia we have had to notice a considerable deve-
lopment of the supplemental skeleton, which sometimes extends itself into i-adiating out-
growths ; and where this exogenous deposit is formed in largest amount, we find the canal-
system most complete and symmetrical. Thus the characters which differentiate Calcarina
from Rolaliu are altogether gradational.

389. Geoc/raphical and Geological Distribution. — The generic type we have now been consi-
dering appears to be pretty widely diffused through the tropical and warmer temperate seas,
but to be limited to these ; the Mediterranean and Adriatic being its extreme northern limit.
Although bodies resembling Calcarina in outward form are occasionally, though rarely, found
in the White Chalk, yet it is not certain whether they belong to this or to the succeeding genus.
The Maestricht beds, however, are crowded with CalcarincB {Siderolince, Lam.), which attain
an extraordinary development, their size much surpassing that of the largest specimens now
living in tropical seas. This type is common in the Grignon Tertiaries, also in the Miocene
of North America, and in European Pliocene deposits ; and I also have examples of it from
deposits in Madagascar and Bourbon, the age of which is uncertain.

Genus XIX.— Tinoporus (Plate XV).

390. History. — For reasons which will be presently explained, I think it well to revive a
generic designation originally instituted by De Montfort in 1808, although, like a large pro-
portion of his new designations, it has been rejected as uncalled-for by subsequent systema-
tists. In his ' Conchyliologie Systematique' (tom. i, p. 147), he described and figured under
the name of Tinoporus baculatus a small polythalamous body, which he seems to have distin-
guished from the other varieties of Nautilus {Calcarina) Sjjenf/leri figured by MM. Fichtel and
Moll, partly by the fewness of its spines, and partly by the difference of its structure as
displayed in vertical section. And although his figure and description are alike
inaccurate (the former, as pointed out by Messrs. Parker and Rupert Jones, lxxvii,
having been partly drawn from specimens of Calcarina), yet I can scarcely doubt that

224 FAMILY GLOBIGERINIDA.

he had before him a specimen of the type I am about to describe, since he distinctly
notices, both in his description and in his rude figure, that cellulation " sur divers plans"
which gives to its vertical section somewhat the appearance of that of a Nummulite.
No sucii appearance is presented by vertical sections of Calcar'uia ; whilst, as will pre-
sently appear, Tinojjorus is made up of several layers of cells superimposed one upon another ;
and although its relation to Nummulina is really remote, yet the resemblance in aspect pre-
sented by vertical sections of the two may easily seem, to such as are unacquainted with the
real meaning of their respective appearances, sutRciently close to justify the parallel. With the
T. baculatm of Montfort it will be shown that we must associate, on account of its close
structural relationship, a type which has been described (lxxix) under the generic designation
Orbitolina, since it may be comprehended in the very vague definition given of that genus by
D'Orbigny (lxxiv) ; and this type is the representative of an extensive series of forms, both
recent and fossil, to which the same definition applies, and to which the name Orbilolina has
been assigned (loc. cit.) by Messrs. Parker and Rupert Jones. Now there is a very grave
objection to such an employment of the term. According to the usage of many systematists,
Orbilolina would be nothing else than the appropriate distinction of the recent forms of Orbi-
tolites ; and even to such as do not accept this usage, the close similarity of name would
assuredly suggest the existence of a structural relationship. But it will presently become
apparent that no such relationship exists, the essential structure of the so-called Orbilolina
being altogether different from that of Orbiloliles, and no real resemblance existing between
them except as regards their plan of growth. Hence it seems very desirable to discard the
name Orbilolina dXiogtiher ; and since another form of the same type had previously been
distinguished by De Montfort, his name Tinoporus may fairly claim to be substituted for that
of D'Orbigny.

391. As the genus Tinoporus presents itself under a considerable variety of external
forms, I think it desirable in the first instance to describe an example that presents what seem
to me the essential features of its structure, and is at the same time free from those complica-
tions by which those features are elsewhere masked.. Such an example I find in the forms
which have been described as varieties by Messrs. Parker and Rupert Jones (lxxix) under
the designations Orbilolina vesicularis, 0. conycsta, and 0. Icevis ; these, as I do not hold their
differences to be of any account, I reunite under the designation Tinoporus vesicularis.*

392. Tinoporus vesicularis : Exlemal Characlers. — -The largest examples I have
seen of this type present the form of a short truncated cone, much resembling the lower half
of a sugar-loaf (Plate XV, fig. 1), having its margins rounded off, and attaining at the base a
diameter of about l-lOtli* of an inch. The base commonly exhibits a slight central depres-
sion. Sometimes the cone is more depressed, and spreads out more widely at the base ; and
in this case the basal concavity is usually wider and deeper. The examples I have seen from

* In my previous description of tliis type (xvi), I designated it T. Icevis ; but I thiuk it better to
substitute the specific designation vesicularis, under which one of its varieties has been described else-
where, as better agreeing with the generic name; — " a smooth" " stick- bearer" being a contradiction in
terms.

GENUS TINOPORUS 225

other localities have for the most part a spherical or spheroidal shape ; but a careful examina-
tion will generally make it apparent that this shape is derived (so to speak) from that last
mentioned, by the folding-inwards of its peripheral portion towards the centre of its lower
surface, so as to leave a deep cavity at that part of the sphere, — the relation of the two
forms being very much like that which exists between the expanded pileus of an Agaric,
and the same jji'/cus whilst still included within its volva. I cannot regard these diversities
of form as possessing any specific value ; since they depend entirely upon mode of growth,
and are not connected with any differences of internal structure. In whatever form the
T.vesicularis may present itself, it is recognised by the absence of projection or angularity, and
by a regular areolation over its whole surface, which a good deal resembles that of the cuticles
of many leaves, the areolae preserving a tolerably constant average of size, but being very inde-
finite as regards form. The septal divisions are marked by a very definite limbation, sometimes
formed of continuous ridges of shell-substance, and sometimes of rows of granules ; and in the
interspaces between these, under a sufficient magnifying power, minute punctations may be seen,

393. Internal Structure. — When the structure of this organism is examined by means of
sections taken in different directions, it is found to be composed of an aggregation of minute
chambers of nearly uniform size, which are piled one upon another in pretty uniform layers,
eachof these presenting an approach to a concentric disposition (Plate XV,figs. 2, 3). Although
it is difficult to make out with certainty the arrangement of the first-formed chambers, yet it is
clear that as in other Foraminifera the point of departure is a spheroidal cell (fig. 3, a), wliich
soon comes to be surrounded by a cluster of secondary cells [b, c) derived from it by gemma-
tion. In what manner these are given off from the first, — whether by a spiral or by a cyclical
extension of the sarcode-body, — I have not been able to satisfy myself, on account of the
difficulty of precisely carrying the plane of section through this group of chambers. In T.
baculaliis I have been fortunate enough to do this in several instances, and have found that the
early growth is unquestionably spiral (fig. 12), — soon, however, giving place to the cyclical, as in
those varieties of Orhitolites whose growth commences after the same fashion (^ 180) ; and
whether this be or be not the case in T. vesicularis, it is indubitable that before long the
extension of the organism in diameter is effected by abudding-forth of new chambers from all
parts of the circumference, not with such regularit}', however, as to form distinct annuli like
those of Orhitolites. Whilst this extension is taking place peripherally, additional layers of
chambers are formed, as in Orbiculina, above and below the primordial cluster, meeting eacli
other on the equatorial plane ; and in this manner the increase of the organism in thickness is
effected. The grov>'th on the two sides of the equatorial plane, however, is seldom or never
symmetrical ; and that of the more convex portion seems continually tending to overpower
that of the opposite surface, so that the equatorial plane becomes more or less deeply concavo-
convex. I have reason to believe that this inequality is due to the attachment of the flat or
subconcave base to the surface of sea-weeds or zoophytes ; in virtue of wliich it will naturally
happen that the free side will grow faster than the other. It is by an excess of this predo-
minating growth that the spheroidal form is acquired, with its deep residual cavity, as just
now described.

394. On more minutely examining tiie structure of the walls of the chambers and the

29

CtP

<£P

226 FAMILY GLOBIGERINIDA.

mode of communication between their cavities, we find that their liorizontal partitions or

floors are perforated by numerous large pores (Plate XV, figs. 2, 3, 4) which closely resemble

those of the shell of a Botalia or a Planorhulwa in their size and arrangement ; and these

will allow of free communication, by pseudopodial threads of sarcode, between the segments

that are lodged in the chambers piled vertically one over the other. The vertical partitions are

V VV1-T much thicker, and are not thus minutely and regularly perforated ; but

r IG. AAAvi.

they exhibit a small and variable number of large apertures (fig. 4, a, a),

that lead into the adjacent cells which lie in or near the same horizontal

_5s «2 plane. I say in of near, because it is seldom if ever the case that the

-^p horizontal partitions or floors of two adjacent vertical piles of cells are

~^___2* on the same level ; and, in fact, the typical arrangement (though fre-

quently departed from) seems to be, that there is an alternation in the
levels of the floors of adjacent piles (as shown in the accompanying
diagram, based on some parts of fig. 3), and that every chamber in any pile b normally com-
municates with two chambers in each of its adjacent piles a and c, by one passage above
and the other below the floor that divides them. Neither the horizontal floors nor the
vertical partitions consist of more than a single lamella.

395. TiNOPOBUS BACULATUS. — The original t3'pe of the genus, namely, the T. haculatus
of De jNIontfort, agrees closely with T. vesicularis in the fundamental characters of its organiza-
tion, but differs in being furnished with a variable number of radiating appendages that give
it a strong external resemblance to Calcarina. Of the specimens in my possession, the
greater part present the aspect represented in Plate XV, figs. 6, 7, and on a larger scale in
fig. 5 ; and these were collected from coral reefs in various parts of the Polynesian Archi-
pelago,— my earliest acquisition of them, however, having been from the contents of the
stomach of an Eehinus taken on the coast of Borneo, which were kindly put into my hands by
Dr. J. E. Gray. I am informed by Mr. Denis Macdonald that on certain coral islands which
he has particularly examined, these organisms are so extraordinarily abundant, that they
accumulate in the lagoons in regular strata, commonly alternating with strata of OrbitoUtes.
The more massive and ruder forms represented in Plate XV, figs. 8, 9, occur in Mr. Cuming's
Philippine collection.

396. External Characters. — The typical form of the central portion of Tinoporns baculatus
may be considered as an oblate spheroid; sometimes, however, the organism is nearly
spherical, and sometimes it is much flattened out, especially when the body extends itself
into the radial prolongations. Its surface is divided into areolos (fig. 5) very much as in T.
vesicularis ; but the angles of junction of the partitions between the areolae ai-e very commonly
occupied by rounded projecting tubercles, strongly resembling those of Calcarina. The
number and size of these tubercles vary greatly among different individuals, as will be seen
on comparing figs. 6 and 7. They seem to be altogether wanting in the Philippine specimens,
being apparently replaced by a multitude of small spines, which give to the surface a hispid
aspect. From the marginal portion of the central disk there spring a variable number of
conical prolongations having the furrowed surface of those of CV//fw;'»«; and these appear
seated (so to speak) upon extensions of the central disk itself, which is sometimes so deeply

GENUS TINOPORUS. 227

subdivided at its margin as to resemble the body of a Star-fish (figs. 7, 9), the areolar division
being continued nearly to the extremity of each ray, and its point only being formed by the
furrowed prolongation. These appendages are usually from four to six in number ; I have occa-
sionally seen only two, and in no case have I met with more than eight. They usually diverge in
or near the equatorial plane; but they sometimes come off in very different directions (fig. 8).

397. Internal Strudare. — The general organization of T. baculatiis, brought into view
by sections taken in different directions, does not differ in any essential respect from that of
T. vesicularis ; the origin of the whole aggregation of chambers in a central cell, their subse-
quent multiplication both horizontally and vertically, and their methods of communication in
both directions, being all the same. As already mentioned, I have very distinct evidence, in
sections of this species, of a spiral commencement (fig. 1 1 a), soon giving place to an irregu-
larly-cyclical growth {b, h) ; and it is remarkable that the first-formed portion sometimes bears
so close a resemblance to the innermost part of the spire of Calcarina, that in this earliest
stage of their growth the two types could not be distinguished from each other. The essential
difference between T. haculatus and T. vesicularis consists in the possession by the former of
a " supplemental skeleton," which presents itself under two principal aspects. The piles of
chambers extending vertically from the equatorial plane towards the two surfaces of the
spheroid are partially separated by the interposition of pillars of solid shell ; and it is by the
projection of the summits of these pillars (as in Calcarina) that the tubercles of the surface
(fig. 5) are formed. The spines also, which form the extremities of the radiating prolonga-
tions, belong to the same system ; and they are shown, by sections that pass in a favorable
direction (fig. 12), to be extended from a solid framework which begins to be formed even
with the first convolution, and which adds greatly to the thickness of the partitions between
the chambers, giving off a multitude of minute spines from their external surface. This
framework is penetrated by a canal-system, which not only forms passages through the solid
axis that is prolonged into the spines (fig. 10, -', b), but also extends itself into the partitions
between the chambers (fig. 10, a, a). The canal-system of the solid axis, moreover, commu-
nicates freely with the cavities of the chambers that are adjacent to it, as is shown at fig. 10, b, b.
These chambers are arranged around it with considerable regularity, as is seen in fig. 11,
which is a transverse section of the base of one of the radiating prolongations, showing the
sohd axis with its radiating canals, surrounded by three rows of chambers. It would seem
as if, in the Polynesian variety of T. baculatus, the material of the supplemental skeleton were
appropriated rather to the formation of the solid pillars than to that of a solid axis for the
radiating prolongations ; the latter being much less conspicuous than it is in the Philippine
specimens, and sometimes appearing to be deficient altogether at their extremities. On
account of the variability of these differences, however, I cannot regard them as of any essen-
tial value.

398. If any further evidence had been required as to the essential relation between
the " canal-system" and the " supplemental skeleton," I think that it must be satisfactorily
furnished by the comparison of the two species of Tinojjoriis now described. For in T. vesi-
cularis it is obvious that the system of communications which exists between its chambers is
adequate for all the ordinary wants of an organism of this type, the structure of which ia

228 FAMILY GLOBIGERINIDA.

uniform throughout. But when, as in T. baculatm, an additional framework of solid walls
is interposed in the midst of the building, for the support of the extensions into which it is
prolonged, a special system of passages, originating from the cavities of the adjacent
chambers, and extending throughout the solid framework^ is provided for its nutrition.

399. Varieties. — The foregoing constitute the only examples of the genus Tinoporus that
are certainly known to exist at present ; but a far larger extent of variation as regards size
and shape presents itself in a group of fossil forms which are probably tobe referred to the
same type. Thus in the Chalk we meet with great numbers of globular bodies varpng in
size from small shot to bullets, having their surface so characteristically marked by a super-
ficial meshwork of septal limbation, that we can scarcely hesitate in regarding them as
examples of the smooth form of Tlnojiorus, although their internal structure has been so
obscured by fossilization as not to show more than the general arrangement of the chambers.*
These are accompanied by conoidal and hemispherical bodies having the like surface ; and
from such we pass to large outspread flattened forms, one of which, the Orh'dolina giyantea
of D'Orbignj^ attains a diameter of nearly four inches. The synonymy of these fossils,
which have been very commonly regarded as Sponges, and referred to the genera Coscinopora
and Tragos, has been fully elucidated by Messrs. Parker and Rupert Jones (lxxix).

400. Affinities. — The relation of this interesting type of structure to that of Phmorhulina
is extremely intimate. For, as in that genus, the first-formed portion of Titioporiis evidently
consists of a flattened disk, consisting of numerous segments which are arranged spirally in the
first instance, but subsequently on a more or less regular cyclical plan. We do not find in
Tinojmrus, however, those tubular and margined apertures which ai"e so characteristic of the
most developed forms of Flanorhulinu ; whilst, on the other hand, we do not find in the most
" acervuline" PlanorbuUtKS that regular piling-up of segments on both sides of the primitive
spire which is characteristic of Tinoporus. The afiinity of Tinoporus bacidafus to Calcarina,
again, is marked not merely by the very close correspondence of their adult forms in external
shape, but by the precise correspondence between the early conditions of the two as regards
their internal structure. Again, we shall find that the curious genus PoJytrema, the place
of which among the Rotaline Foraminifera was long since suspected by the sagacity of
M. Dujardin (xxxvi, p. 259), is only a still more aberrant modification of the same plan of
growth. Lastly, there will be found, when we come to describe the structure of Orbitoides,
a considerable resemblance in plan of growth between that genus and Tinojwrus ; the chief
difference being that in the former type the chambers of the median plane are more differen-
tiated in character and in mode of communication from those which pile themselves on their
lateral surfaces, than they are in the latter. But it seems pretty clear that in its most essen-
tial characters Orbitoides is more nearly related to the cyclical forms of the Nummuline than
to those of the Rotaline series.

* Many of these fossil globular forms, like the recent (1[ 392), have an irregular tubular
cavity on one side, extending to a greater or less distance into the interior ; and such appear to have
been used as beads (the perforation being carried through to the opposite pole) by the old " flint-folk "
of the Valley of the Somme, being common in the gravel that yields the flint implements.

GENUS PATELLINA. 229

40 1 . Gcograpldcal Distribution. — The recent examples alike of the simple and of the baculate
types of Tinoporvs are found in greatest size and abundance in the Australian and Polynesian
seas, occurring chiefly in the shelly sands of rather shallow water ; and T. bamJntm does not
appear to range far beyond those regions. I am informed by Mr. Denis Macdonald (late of
H.M. surveying ship, " Herald"), that on some annular coral islets he has met with Orbito-
lites and Tinojwrus baailatus in most extraordinary quantity, not only on the windward side
of the external shore, but also in their internal lagoon, into which these bodies are washed
by the surf, and in which they gradually accumulate to such an amount as to have an im-
portant share in filling it up. The small spherical forms of T. vesicularis, on the other hand,
are for the most part inhabitants of deep waters, being brought up in dredgings from muddy
bottoms and shell-sands ; and they have also a wider geographical range, having been found
not only in the Australian and Polynesian seas, but in the East and West Indies, at Mazatlan
on the coast of California, in the neighbourhood of Teneriffe, in the Mediterranean, and even
on the British coasts as far north as Arran.

402. Geograpliical Distribution. — The obliteration of the internal structure of the earlier
fossil specimens which we believe ourselves justified in referring to this type, prevents us from
stating with certainty in what strata its first remains occur. From the evidence of external
form and surface-markings, however, it is pretty clear that some of those small spheroidal
bodies in the Greensand, and a large number of those occurring in the various beds of the
Cretaceous series, which have been regarded as Spongeous, are truly referable to the simple
form of the genus Tinoporus. If so, they are not only by far the largest examples of this type,
but are also amongst the largest of the Foraminiferous group. The Cretaceous period would
seem to be that in which this type attained its maximum of development; for although
examples of it occur in the Nummulitic limestone, and in the later Tertiaries of Palermo,
Bordeaux, and San Domingo, these are not of larger dimensions than the recent specimens.
The " baculate" form of this type cannot be distinguished with certainty in fossil specimens
from Calcarina, by external characters alone ; so that it is as yet uncertain whether any of
the radiate and stellate bodies which occur in the Maestricht Chalk and in the Nummulitic
Tertiaries, are or are not the ancestors of the similar organisms at present so abundant on the
reefs and islands of the great Coral Sea.

Genus XX.— Patellina (Plate XIII, figs. 16, 17).

403. History. — Some of the large fossil forms which seem properly to belong to the genus
now to be described, have been referred to the genus Orbitolina (D'Orbigny), whilst another has
received from D'Orbigny the designation, Cyclolina, and another has been described by
Mr. Carter (xxiii «) under the name Comilites ; and its minute recent representatives also have
been referred by Messrs. Parker and Rupert Jones (lxxix) to the genus Orbitolina. For the
reason already stated (^ 390), however, I think it undesirable to adopt the generic term Orbi-
tolina for this type, any more than for the last; and as the definition given by D'Orbigny of
his genus Cychlina is so unsatisfactory as to leave the true character of its type in complete

230 FAMILY GLOBIGERINIDA.

uncertainty,* I have thought it just to Prof. Williamson, who has accurately described and
figured (ex, p. 46, figs. 80 — 89) the recent form that best elucidates the structure of these
fossils, to adopt the generic name Patellina which he has conferred upon this. I shall first
give an account of the recent type F. corrugata, partly based on Prof. Williamson's obser-
vations, and partly on my own examination of more developed specimens obtained by Messrs.
Parker and Rupert Jones from the coast of Australia ; and shall then describe the fossil types
on the basis of Mr. Carter's observations and my own.

404. Patellina corrugata : External Churacivrs and Iiitenial Slnicture. — This very
beautiful but very minute shell has the form of a depressed cone, resembling that of a Patdia,
its diameter being twice or three times its height ; the apex of the cone is occupied by the
primordial segment; and its regularly chambered structure forms only a thin shelly wall, the
interior of the cone being more or less completely filled up by an irregular growth of secondary
chambers. In the British form of this type, the primordial segment is surrounded by two or
more turns of an irregular spiral (ex, fig. 90 a,) reminding us of the outspread spiral of Pul-
vinidina vvrmlcuhita (^ 3G6) ; and the subsequent growth of the cone is effected by the
addition of semi-annuli which interdigitate with one another (ex, figs. 87, 88), so as to present
a certain resemblance to Textidaria in plan of increase. Each annulus or semi-annulus
is described by Pi'of. Williamson as being divided into chamberlets by transverse secondary
septa, which spring from the external margin and pass towards the internal, but which do not
quite reach it ; so that all the chamberlets thus formed communicate with each other by a
continuous passage left along the internal side of the chamber (ex, Fig. 90). This partial
subdivision is marked externally by a crenulation of the surface. The secondary septa in the
British specimens are very commonly wanting, or are merely rudimentary, in the early
vermiculate spiral portion of the cone. Prof. Williamson expresses himself as unable to
determine in what mode the principal semi-annular chambers communicate with each other.
The diameter of his specimens of this organism does not exceed I -80th of an inch. — In the more
highly developed Australian forms of this type, on the other hand, which sometimes attain a
diameter of nearly l-25th of an inch, the growth is cyclical from its commencement; the
primordial segment being encircled by a circumambient segment, as in OrbUolites (^ 157)^
which is often itself partially subdivided, and from which a complete annulus of segments is
givenoff (Plate Xlll, tig. 16) ; and I tind no trace of any subsequent division into semi-annuli,
resembling that described by Prof. Williamson. Moreover, 1 tind that the partitions between
the chamberlets are complete, not merely extending to the margin of the preceding annulus,

* D'Orbigny's definition of CycluUna (Lxxrii, p. 139) is so nearly applicable to OrbitoUtes, that
Mr. Carter was formerly (xix) misled into characterising as a Cyclolina what I have shown to be a mere
variety of OriJio/i/es, and was further misled into characterising the white limestone in which this occurs
as Cretaceous instead of Eocene ; so that, as he has truly remarked (xxui a), "It would have been
better if M. D'Orbigny had never written anytliing about Cyclolina, than just enough to mislead."
There is, in fact, nothing either in his figures or descriptions of this fossil that enables us to identify
it with any certainty; its geological position being the chief point which differentiates it from OrbitoUtes,
and which renders it probable that it is to be associated with those subconical Orbitolince which seem
properly to belong to the genus Patctlina.

GENUS PATELLINA. 231

but being prolonged inwards beneath that margin (.Plate XIII, fig- 17), until the peripheral
chamberlets lose their distinctness by merging into the secondary growth which occupies
the umbilical cavity. The chamberlets are prolonged in a radial direction so as to have a tubular
form ; but not unfrequently we find that as we trace them from without inwards two of them
coalesce into one, as often happens in Cymbalopora. Owing to the conical arrangement of the suc-
cessive annuli, only a small part of each (except the last) is seen where it crops out upon the sur-
face, the remainder being concealed by those above and below it. The external walls of the
chamberlets are perforated with a few minute pores ; but those which separate the chamberlets
and annuli from each other are altogether imperforate, so far as I have been able to distinguish.
— The interior of the cone, in the British specimens of this type, is described by Prof Williamson
as partly occupied by an exogenous deposit of hyaline shell-substance, possessing no regular
arrangement ; and this seems evidently analogous to that which fills up the umbilical vestibule
in the most developed forms of Botalia, and which tends to form a secondary chamber-struc-
ture in the " asterigerine" BiscorhincB. This umbilical deposit seldom fills the cone so com-
pletely as to conceal the last annulus, which is consequently the one best seen from the under
side, and frequently the only one there visible (ex, fig. 89). In the larger Australian forms it lias
a distinctly loculated structure ; its chambers, however, are not arranged with any regularity,
but constitute a system of intercommunicating lacuna hollowed out in the midst of a mass of
solid shell-substance ; and in this system the chamberlets of the peripheral annuli appear to
terminate at their Central extremities, just as the chambers of Cymhalopora communicate with the
umbilical vestibule. I find it impossible, however, to speak with the confidence I would
desire upon this point ; for notwithstanding the beautifully hyaline texture of this shell, its
very small size as a whole, and the minute subdivision of its parts, render the examination of
its internal structure very diflicult. The still more minute forms described by Messrs. Parker
and Rupert Jones (lxxix) under the names OrhitoUna simplex and 0. semianuularis, are
obviously young or imperfectly developed examples of the type that has now been described.

405. Patellina concava : External Characters and Internal Structure. — From the
Nummulitic limestone of the Pyrenees I have fossil specimens which resemble the preceding
in form and in superficial characters, but which are of comparatively gigantic dimensions,
attaining a diameter of 1-4 th of an inch; these appear to me to be identical in structure
(so far as their metamorphic condition allows me to judge) with the fossil which has been
recently described by Mr. Carter (xxiii a) under the name OrhitoUna lenticular is, being re-
garded by him as identical with the species so named by Blumenbach, which had been first
described and figured by Deluc (' Journal de Physique,' torn. Ivi, p. 344). I believe them also
to be identical with the OrhitoUna conica of JJ'Archiac (' Mem. Soc. Gdol. France,' torn, ii,
p. 178), and the 0. conoidea of Gras, (' Foss. de I'lsere,' p. 51, pi. i, figs. 4 — 6), from the
Cretaceous beds of France, as also with the 0. discoidea of Gras and the 0. plana and 0.
mamillata of D'Archiac. As all these appear to be varieties of the 0. concava of Lamarck, it
seems convenient to adopt this last (as Messrs. Parker and Rupert Jones have done, lxxix)
as the specific designation of the type, since it expresses a form intermediate between its
conical and its discoidal varieties.* The form of this fossil (Fig. XXXVII, a, b, c) seems to

* I must freely confess, however, tliat I am not as 3'et prepared to say with certainty what of

232

FAMILY GLOBIGERINIDA.

vary from that of a high to that of a depressed outspread cone ; and the diameter of the Indian
specimens ranges between l-8th and 2-3rds of an inch, the smallest being relatively the highest.
The general plan of structure of this fossil corresponds with that of the recent Patellina ; the
cone being formed externally of a succession of annular segments subdivided by transverse
partitions into chamberlets (d, 3) ; whilst its interior is more or less completely filled up by a
secondary umbilical growth. But there are two very important differences in detail. In the
first place, each of the chamberlets of the annular series is again partially subdivided into four
or more, by septa which project from tlieir external wall, but which do not extend above half-
way towards the interior (Fig. XXXVII, d,2,3, g,1,2); so that the surface of the cone

Fig. XXXYIT.

Patellina lenticularis : — A, B, c, couical surface, basal surface, and edge view, one half larger than the natural size:
— D, Diagram showing 1, arrangement of chambers at the centre or apex, which is at first more or less confused, and then cyclical ;
2, external or reticulated chamber-lajer; 3, subjacent or large chamber-layer; 4, engine-turned arrangement of chambers
below the last-mentioned layer : — e. Magnified view of portion of patulous surface, to show the arrangement of the ends of
the columnar chambers in tiie form of granulations : — f, Horizontal section, showing, 1, reticulated layer ; 2, large chamber-
layer ; 3, colunuiar chamber-structure : — G, Vertical section of half the fossil, showing, 1, reticulated layer externally ; 2, large
chamber-layer; 3, columnar chamber-structure. — After Carter.

shows a very minute subdivision of its external layer, whilst the removal of this brings into
view the larger chamberlets formed by the primary subdivision of the annulus. This
arrangement is represented in the accompanying figures, which are copied from Mr. Carter's
somewhat diagrammatic delineations. I feel certain, however, that in my own specimens
the large chambers of the peripheral annuli are prolonged inwards in a radial manner much
further than Mr. Carter represents them, and that they communicate freely with those
which fill up the hollow of the cone, instead of being terminated on their inner side by
transverse walls. The umbihcal growth consists of an aggregation of compressed chambers,
which are described and figured by Mr. Carter (d, 4) as having an engine-turned arrange-
ment ; and these rest one upon another in columnar piles, more or less completely filling
the cone, and sometimes extending even beyond its base, so as to give this a convex surface.
This surface is marked by tubercular granulations (e), which probably result (like those of
Tinojwrus, ^ 392) from septal limbation. In my own specimens of this fossil, the

the Orhitolinm of Lamarck and subsequent writers are to be referred to the genus Tinoporus, and what
to the genus Patellina ; since their forms are derivable from those characteristic of either type, and
their internal structure is seldom sufficiently well preserved to afford the means of positive diagnosis.
I am inclined to believe, however, that all those conoidal, lenticular, or discoidal forms which exhibit a
more or less distinct animlation are true Paiellinte.

GENUS PATELLINA.

233

umbilical chambers have been so completely altered in fossilization, that I can give no
account of their structure; and it is to be regretted that Mr. Carter, whose specimens
appear to be in better condition, should have given so imperfect a description and so merely
diagrammatic a representation of it. But I can scarcely hesitate in the belief that this
columnar chambered structure must essentially correspond with that which we have seen in
Tinopoms (f 394), and with which we shall meet again in Orbitoides (^^ 505, 506). It
seems most likely that the discoid fossil which has been designated CychUna crclacea by
D'Orbigny, is nothing else than a very outspread form of the Orbitolina lenticuhriH of
Lamarck, which is probably to be regarded as the fully developed type of our genus Patellina,
the recent forms being comparatively feeble. Such a form, agreeing in all essential parti-
culars with the foregoing, has been recently described by Mr. Carter (xxiii a). On the
other hand, Mr. Carter has met with the same type of structure in very high conical forms ;
and in some of these the reticulation of the surface is wanting, and the septa are indistinctly
developed. It is not a little curious that in some of these there should be exactly the same
disposition of semi-annular imperfectly subdivided chambers interdigitating with each other,
as has been described in the recent P. corritgata (^ 404).

405. Patellina Cooki : External Characters and Internal Structure. — The lossil de-
scribed by Mr. Carter (xxiii a) under the new generic name Conulites does not appear to me
to differ so essentially from the preceding in general plan of structure as to require being
generically separated from it. Like P. lenticularis, it is a more or less depressed cone (Fig.
XXXVIII, A, B, c), of which the exterior is formed of a series of chamberlets ( G, 1) arranged in

Palellina Cooki: — A, B, c, Conical surface, basal surface, and edge view, one half larger than the natural size : — D, Central
portion of the spire and chambers magnified, as seen on the surface after the incrustation of the apex has been removed : — e,
Vertical section of lialf the fossil, showing, 1, incrustation ; 2, lateral view of chamber-layer ; 3, horizontal layers of chambers ;
4, opaque, white columns of condensed shell-substance : — F, Basal surface, showing, 1, ends of the columns of white substance ;
2, ends of the columns of chambers :—g. Horizontal section, showing, ], part of the spiral chamber-layer ; 2, truncated ends of
opaque white columns ; 3, ditto, of columns of chambers. (After Carter.)

regular succession, whilst the interior is filled by columnar aggregations of compressed
chambers ( g, 2). The arrangement of the chamberlets of the exterior, however, seems from

30

234 FAMILY GLOBIGERINIDA.

Mr. Carter's figure and description to follow a regular spiral plan throughout (d ), the spire
being continuous from the base to the apex of the cone ; and the chamberlets are simple as
in P. corrit(/ata, not again subdivided as in P. lenticularis. The upper part of the cone is
covered by an exogenous deposit of shell-substance (c, 1), which gradually subsides, about
half way down the cone, into granulations that project in rows from the septal bands, forming
a superficial limbation. On the other hand, the chambered structure of the interior of the
cone is strengthened by solid columns of a somewhat conical form (e, 4), the apices of which
are directed to the interior of the cortical layer, whilst their bases form large tubercles which
project from the basal surface ( f, 1). These columns are obviously analogous to those which
we have seen to be formed in Tinoporus haculatus by the accumulation of solid shell-substance at
the meeting angles of the septa which divide tlie piled-up chambers (^ 397) ; and the whole
description given by Mr. Carter justifies the belief that the chambered structure is essentially
the same in the two cases. Now, from what we have already seen in Tinoporus, and from
what we shall hereafter find to be the case in OpercuUna, Nunimulina, and Orbitoides, it may
be stated with certainty that the presence or absence of these sohd columns is a character so
extremely variable as not in itself to have even a specific value. And when the account
already given of the recent Patdlina is taken in connection with the facts formerly stated
in regard to the varieties in plan of growth shown by OrhitoUtes and OrhicuUnn, it becomes
obvious that the persistence of the early spiral succession through the whole period of
increase is not in itself a character of sufficient importance to constitute a specific differen-
tiation ; more especially as we are informed by Mr. Carter that the spire is subject to irregu-
larities, sometimes becoming double. The subdivision of the superficial portion of the
chambers of P. lenticularis, however, if it should prove to be a constant character of that
type, and to be altogether wanting in P. Cooki, would be held sufficient for the specific
differentiation of the former from the latter.

406. Affiniiies. — So far as the minuteness of the recent examples of this genus, and the
imperfect preservation of its larger fossil specimens, allow us to form an opinion of its affini-
ties, these appear to connect it, on the one hand, with those aberrant forms of the Rotaline
series in which the spiral tends to give place, at an earlier or later period, to the cyclical plan
of growth ; whilst, on the other, it seems related to the minutely sub-divided spiral and
cyclical forms of the Nummuline series. There is something in its sharply defined trochoid
cone which strongly reminds us of the typical Pulvinuliins ; and although it is only in the
P. Cooki that the spiral plan of growth is maintained throughout, yet the vermiculate spiral
in which P. comyata often commences no less strikingly resembles that of the complanate
forms of Pulviniilina. And it seems further to be allied to that genus, rather than to Discor-
hiiia or to PianorbuJina, in the fineness of the porosity of its shell. To Discorhina, how-
ever, it is specially related in the occupation of its deep umbilical cavity by an aggrega-
tion of secondary chambers, which thus conceal its inferior lateral surface ; and in its general
plan of growth it may be considered as specially related to Ci/nibalopora. The relation of the
large, highly-developed, fossil forms oi Patelliiia to the conical, outspread examples oi Tinoporus
seems to be exceedingly intimate ; the essential difference appearing to lie in the limitation
of the secondary chamber-growth to one side, and in the distinctness of that growth from the
layer in which the organism originates. At present it can scarcely be said with certainty what

GENUS POLYTREMA. 235

fossil forms are to be referred to these two types respectively ; and the diagnosis will probably
rest essentially on this, that whilst the surface-markings of the ujiper and under side are alike
in Tinoporus, though one side may be convex and the other concave, the convex side of Fatel-
lina always shows either a continuous spiral or a succession ofannuli of chamberlets.

407. Geographical and Geological Disfribxtion. — The little PaiellincB which constitute the
existing representatives of this genus are very generally diffused, but do not seem to be any-
where very abundant. They have been found in Arctic, British, Mediterranean, Indian, and
Australian seas, between the littoral zone and depths of five hundred fathoms. — If we are right
in identifying with this type the Orbitolina lenticularis of Blumenbach and the Ci/clolina
crcfarea of D'Orbigny, this genus was highly developed at the Cretaceous epoch ; and the
same fundamental type seems to have presented itself under great diversities of form,
twelve or more different specific names having been given to its varieties. This genus is also
represented, as we have seen, by examples of considerable size in the Eocene Tertiaries of
India. Subsequently, however, it seems to have declined ; the Patellvia of the Grignon sands
being neither so large nor so well developed as those at present existing in the Australian
seas.

Ge?mXXl.— PoLYTREMA (Plate XIII, figs. 18—20).

408. History. — The genus Polytrema was instituted by Blainville (vi, «),for the reception
of the curious little bodies which had been previously described by Lamarck (lx), under the
name of Millepora rubra. Neither of these systematists appears to have entertained any
doubt of its Zoophytic character ; but its probable relationship to the Foraminifera was sug-
gested by Dujardin {xxxvi, p. 259), who, after speaking of the probably Rhizopodal nature
of Rofalia, PkuiorbitUna, &c., continues : — " J'ai bien constate que toutes les loges sont occu-
pees ^ la fois par la substance glutineuse ; mais je n'ai point vu les expansions filiformes, non
plus que dans le Polytrema rubra, que je conjecture appartenir a cette meme famille d'apr^s
la nature de la partie vivante." A similar view was afterwards taken by Dr. J. E. Gray
('Proceedings of the Zoological Society,' April 27th, 1858), who further suggested that Polu-
trema might be specially related to Carpentcria, an idea which is not confirmed by examina-
tion of the internal structure of these types.

409. External Characters. — Of all Foraminifera there is none so decidedly Zoophytic in
its form and Irnbit as Polytrema ; for although it sometimes spreads itself as a scaly incrusta-
tion on the surfaces of shells, corals, &c., it not unfrequently rises from those surfaces in an
arborescent form ; whilst sometimes its stalk, instead of branching, swells into a globular
protuberance, which bears a strong resemblance in size and general aspect to the globular
form oi Tiiioporim (Plate XIII, fig. 18). The surface is always areolated, but the character of
the areolation is not uniform, even on different parts of the same specimen ; for sometimes the
boundaries of the areolae are elevated as in Tinoporus, sometimes a little depressed as in Car-
pentcria, while sometimes they are on the same level with the spaces they enclose, and are
only distinguishable by their difference of texture, the areolae being porous, whilst their boun-

236 FAMILY GLOBIGERINIDA.

daries are formed by solid shell-substance (fig. 19, a). In the arborescent forms oi Polytrema
it is generally to be noticed that the extremities of the branches are rugged, instead of being
smoothly rounded off; and when these are looked at with a sufficient magnifying power, they
are seen to present several openings of considerable size (fig. 19, IJ). Similar openings are
sometimes observable in the solid spheroidal forms. Occasionally, moreover, solid tubercles
resembling those of Tlnoporiis haculatus are seen on the surface of the spheroidal forms. It
is a fact not undeserving of notice that specimens of Po///'/-e/«a which have been kindly placed
in my hands by Mr. Denis Macdonald (late of H. M.S. "Herald"), were completely coated over
with a membranaceous Sponge, the spicules of which seemed to radiate from the extremities
of the branches. Of the parasitic characters of this sponge, I can entertain no doubt what-
ever ; and it is a fact of some importance with regard to the presumed spongeous characters
of the body of Carpenferia (■[ 31.3), that although (as will be presently seen) the openings at
the extremities of the branches of Polyfrcma communicate very freely with the chambered
interior, I have not been able to find the least trace of the penetration of the spongy parasite
into its substance.

410. Infernal Stmcfitre. — When the interior of Polytrema is laid open by section
(Plate XIII, fig. 20), its structure is found to be essentially the same with that of Tinoporus,
but less regular, and with freer communications between the chambers. In the arborescent
forms it is generally to be observed that in the centre of each branch there is a cluster of
longitudinal canals (a, a), each of which seems to have been formed by the coalescence of
several segments, or rather to result from a want of segmental division ; and it is
by the termination of these canals at the extremities of the branches, that the openings are
formed which are commonly seen there. The canals communicate with each other
and with the surrounding chambers by large, circular orifices ; and similar orifices of
communication, though of smaller size, are observed between the chambers elsewhere ;
but sometimes there are spaces of considerable size which present scarcely a trace
of subdivision, so as to bear a considerable resemblance to the chambers of Carpenleria. Thus
the whole shelly texture has ordinarily a less solid character than that of Tinoporus, although
formed on a plan essentially the same ; but we occasionally find an aggregation of calcareous
substance in solid pillars {b, b) exactly resembling those which we have seen in T. bnculatus
and in PateUina Cooki. The presence of these appears simply due to an exuberance of calci-
fying material; and it is obvious, from their extreme variability of distribution, that no reliance
can be placed upon them as furnishing differential characters. I have not been able to ascertain
with certainty the mode in which the growth of Polytrema commences ; but from the indica-
tions presented by the youngest specimens in my possession, I have little doubt that its
original development is essentially " planorbuline ;" that is, that its early segments are arranged
in an outspread spire, attached by its flat side ; and that when its growth becomes " acervu-
line," the newly added segments tend to go on piling themselves upon its upper surface,
instead of extending the disk horizontally.

'o

411. Affinities. — No lesson can be more instructive to the systematist who aims to
arrange the Foraminifera upon truly natural principles, than to trace out the affinities of this
singular genus. At the first statement of the proposition that the zoophytoid Polytrema is

GENUS POLYTREMA. 237

nothing but a modified Rotaline, any person unacquainted with the essential characters of
this group might be excused for incredulity. But I cannot question that any candid
inquirer, who, having first mastered my general principles, may have followed me through
the preceding details, will be disposed to acquiesce even in this remarkable result. If it be
true that the character of the individual segments, as marked by the texture of the shell and
the mode of communication of the chambers, is a character of more importance than the
form which these segments may develope by their aggregation, then it cannot be questioned
that the serial assemblages of " globigerine" chambers {% 270) which form the turbinoid spire
of Discorbina, the outspread disk of Planorbulina, the conoidal or spheroidal mass of Tino-
porus, and the arborescent ramifications of Polyirema, are all most intimately related one to
the other. In the general plan of its chambered structure, Poli/frema is obviously most
nearly allied to Tinojiorm ; but if I am correct in the idea I have formed of its early mode of
growth, its fundamental affinity is rather to Planorbulina, since its subsequent increase takes
place, as in. that genus, upon only one side of the original spire, instead of upon both sides as
in Tinoporus. It is not a little curious that there should be a strong external resemblance
between Poh/trema and some of the less regular forms of Carpenteria ; a resemblance which is
increased by the presence of free openings at the extremities of the branches in the former,
and by the precise conformity which its areolation often presents to that of Carpenteria. The
relation is one, however, of mere isomorphism, as we have seen the internal structure of the
two organisms to be essentially different.

412. Geographical Distribution. — All the specimens of this genus hitherto collected have
been obtained from the surfaces of shells, zoophytes, stones, &c., brought from tropical or
sub-tropical regions ; the large foliated bivalves of the Indian and Polynesian seas being its
favorite habitat. — We have not as yet any certain knowledge of the occurrence of this type
of structure in a fossil state ; but it is very probable that a considerable number of the arbo-
rescent fabrics which have been detached by D'Orbigny from the genus Ceriopora and thrown
into Polytrema will prove on examination to be referable to it, and will have to be removed
from the Bryozoa, with which they are at present associated.

CHAPTER X.

FAMILY NUMMULINIDA.

413. The Nummulites and their alhes, as they are the most gigantic, are also the most
highl}^ developed representatives of the Foraminiferous group : their structure presenting
in every particular an advance upon that of the types already described. It is in this
family that the shell attains its greatest density, that of some genera being of an almost
ivory-like toughness ; and this character seems in some way related to the exceeding
fineness of its tubularity, being most pronounced in those cases in which the tubuli
are most minutely and most regularly disposed. It is here, too, that we find it to be a rule
without exception, that the septal plane is completely differentiated from the rest of the shell,
the ordinary tubular structure being deficient, and no other passages than the principal
aperture existing in the septum, except a few large " orbuline" pores. Again, it is here a rule
almost without exception that the wall of each chamber is complete in itself, instead of being a
mere " tent ;" hence each septum consists of two laminae, one belonging to each of the cham-
bers which it divides ; and between these laminae is interposed a set of radiating canals, which
communicate with a system that passes along the successive turns of the spiral or the annuli
of the cyclical disk — according to the plan of growth. The development of this canal-system
is related to that of the " intermediate" or "supplemental skeleton," which is here in almost
every instance superadded to the proper walls of the chambers, consolidating into one compact
fabric what would otherwise be a series of slightly connected segments.

414. The typical plan of growth in this family is a symmetrical spiral, with progressive
increase in the breadth of its convolutions, giving to the shell more or less of the character
of that of a Nautilus or an Ammonite. And, as a general rule, each convolution invests the whole
of the preceding on both sides ; the spiral lamina of shell being continued to the umbilicus, even
where it so closely adheres to that which it overlies as to leave no space whatever for the
extension of the soft body between the two. In the typical Niimmidin(P, however, each
segment of the body gives off a pair of alar lobes (^ 71), which prolong themselves to the
umbilicus in alar extensions of the chamber which it occupies. These alar lobes, moreover,
in certain Xtimmulinida, are detached by intervening septa from the segments to which they
seem properly to belong, and may even be broken up into small sub-segments, so as to form
on either side of the spire an overgrowth of secondary chamberlcts which bears a strong
analogy to that of Tinoporus. Even in those genera, however, in which the complete invest-

FAMILY NUMMULINIDA. 239

ment of the earlier whorls by the later is the typical plan, we not unfrequently find that llie
last convolution tends to detach itself from the spire, being adherent to its margin only, and
flattening itself out into so remarkable an extension as often completely to alter the original
contour of the shell. The aperture, in the typical nautiloid forms of tiiis family, is a narrow
fissure that is left between the outer margin of the penultimate convolution and the inner
margin of the septum ; and alike in its form, and in its position with regard to the two lateral
surfaces of the shell, it is consequently quite symmetrical. The fissure may, however, be
bridged over by processes of shell, so as to be converted into a row of discrete pores.

415. The NuMMULiNiDA which conform to this general plan of symmetrical spiral
growth, may, therefore, in some respects, be considered as more nearly related to the higher
Lagenida than they are to the BotalincB ; for in respect to the nautiloid form of its shell, and
the fineness of its texture, there is an obvious resemblance between Cristellaria and Opercu-
liiia. But we shall find that this resemblance is superficial only ; the latter possessing a
complex internal structure which is wholly wanting in the former, but to which we have
found a very decided approach in the most elevated forms of the genus Botcdin. Now, it is
not a little remarkable that whilst llotulia thus forereaches on the Nummulinida, we should
find among Nummulinida a most distinct reversion to the Rotaline type ; the genus J//;yj///.s'-
ti'fjina having not only a unsymmetrical spire that sometimes approaches the turbinoid forui,
but having its aperture also on the under side of the spiral plane, and being also destitute
alike of the double septal laminae and of all trace of canal-system. In these last respects,
therefore, it is decidedly inferior to the highest forms of Rofalia ; yet in the arrangement of
its alar lobes and in its general morphology it conforms so closely to the Nummuline type,
that there can be no more question of its title to a place in this family, than there can be as
to the retention of the true Rofalia anionsr the Rotaline Globigerinida.

's

416. In the genus Polt/stomella, again, some of the characteristic features of the
Nummuline type are almost entirely absent ; the texture of the shell being far less elaborate,
the alar extensions in the later whorls being often deficient, and the spire being frequently
in some degree unsymmetrical. But we have, on the other hand, in this type, the highest
development of the canal-system that we anywhere meet with ; and even in those simple
" nonionine " forms which are among the most degraded examples of the Nummuline series.
we find this canal-system presenting a definiteness and symmetry much greater than that
which it exhibits in the most developed Rotalta.

417. Passing onwards now from the typical NimmulincB to a higher plan of growth,
instead of reverting to a lower, we find that by a process of subdivision exactly analogous to
that by which a Pcneroplh becomes an Orblculina, the undivided chambers of Ojjcrculina are
converted into the rows of chamberlets, whose regular soiral increase is the essential cha-
racter of the genus Ileterostegina. If, however, this increase should take place on the cycli-
cal plan, as in Or/jitolifes, instead of on the spiral, we have a Ct/cIocIi/peHS, a type in which
the plan of structure of the individual segments is so completely conformable to that whiili
prevails in IIeicrostc(jhia, that marginal fragments of the two could no more be distinguished
from each other than could marginal fragments of Orhilolites and OrbicuUna. And, finally,

240 FAMILY NUMMULINIDA.

in Orbitoides we have the discoidal plane of cyclically arranged chamberlets, overgrown on
either side with piles of flattened secondary chamberlets, which on the one hand bear a strong
resemblance to those of Tinoporus, and on the other are analogous to those formed by the
subdivision of the alar lobes in certain Nummul'mce. In regard to complexity of structure,
Nummulina and Orbitoides may be considered as holding a corresponding rank ; and it is very
interesting to remark that these two types attained their highest development at the
same geological periods, and that they represented each other in different localities.
Owing to the metamorphic condition of the shell of FusuHua, a type which is only known
as occurring in the Palseozoic series, it is not certain whether it is to be rightly referred to
this family, or should be placed in the porcellanous group in close proximity to Alveolina,
which it resembles in its plan of growth ; and the only reason I can advance for regarding it
as an early and somewhat rude representative of the Nummuline type, is afforded by faint
indications of a tubular structure in its shell, and by an appearance of duplication in its
septal lamella.

418. According to the system of M. D'Orbigny, the genera which we group together in
this family would be distributed under three of his orders, as follows :

Order II. — Cyclostegues. Cycloclypeus, Orbitoides.

Order IV. — HELicosxiiGUES. Fusulina, Nummulina, Operculina, Polystomella
(including Nonionina).

Order V. — Entomostegues. Amphistegina, Heterostegina.

In our view their affinities may be represented somewhat as follows:

FAMILY NUMMULINIDA.

Amphistegina.

Polystomella Nummulina

Nonionina Operculina .

Fusulina ? Heterostegina . Cycloclypeus . Orbitoides-

Alike by Amphistegina and by Polystomella this family is connected with the genus
Eotalia ; whilst by some of its most degraded Nonionine forms Polystomella is related to
Pulvinulina. The relation of Heterostegina to Orhivulina, and of Cycloclypeus and Orbitoides to
Orbitolites, is one of analogy only, arising from the similarity of their respective modes of
growth, and is no more indicative of any real affinity than is that which arises out of the
superficial resemblance between Peneroplis and Operculina, two types which are separated
from each other in every character of real importance as widely as any two polythalamous
Foraminifera can be.

GENUS AMPIIISTEGINA. 241

419. It is a point of no slight interest in regard to the Geographical Distribution of this
family, that it is scarcely at all represented at the present time in the seas of temperate
or arctic zones, being almost exclusively confined to tropical or sub-tropical regions. The
few examples that occur nearer to the poles than to the equator are the least developed of
their respective genera, in regard both to size and to complexity of structure ; whilst the
larger and more developed forms of those genera, like the great J/eferosfr</ina and the
gigantic C//duch/pe/fs, are only to be met with between or near the tropics. This fact is one
of considerable interest and importance in relation to the question of the climate tliat
prevailed in Europe during the earlier portion of the Tertiary Epoch.

Genus I. — Amphistegina, (Plate XIII, figs. 22 — 29.)

420. History. — This genus was first constituted by M. D'Orbigny in 1825 (lxix) for the
reception of a type of Foraminiferous shells whicli does not seem to have been previously
distinguished by systematists who have given their attention to this group, in consequence,
it may be, of its limitation to the seas of warm latitudes. Notwithstanding the very close
relationship which it will be presently shown to bear to JVummulinida in general plan of struc-
ture, it was considered by M. D'Orbigny to depart from them in a character which he
regarded as of such fundamental importance as to serve for the basis of a distinct order, that
oi Enfomosteffues, of which the following is his most recent definition (lxxiv) : " Animal com-
pose de segmens alternes, formant une spirale. Coquille composee de loges empilees ou
superposees sur deux axes alternant entre elles, et s'enroulant en spirale." The mode of
increase in these shells, he elsewhere says (lxxiii, p. 199), presents a singular mixture of
that of the Eiiallostegiies with alternating chambers, and of the spiral involution of the Heli-
costefftces. I have already pointed out that such a combination does actually exist in Cassi-
diclina (^ 3.38), which, so far as I know, is the only type that exhibits it ; but the alternation
of chambers supposed by M. D'Orbigny to characterise Amphistpgiiia will be found not to have
a real existence. His account of it, however, has been taken upon trust by all those Natu-
ralists who have adopted his system ; the only investigator, so far as I am aware, who has
questioned his views being Prof. W. C. Williamson, who, in his extremely valuable memoir
" On the Minute Structure of the Calcareous Shells of some Recent Species of Foraminifera"
(cviii), gave an account of the Amphisieyhta fj'ibbosa of the West Indian seas, which, as far as
it goes, is extremely accurate. He rightly apprehended the fact of its close conformity to
the Nummuline type, save in the fact of the want of symmetry which is occasioned by the
turbinoid declination of its spire ; but he failed to detect that peculiar " asterigerine" arrange-
ment of the alar prolongations on the under side, the misinterpretation of which seems
to have been the source of M. D'Orbigny's erroneous conception of the essential cha-
racters of this type. Tlie elucidation of the real nature of these is due to Messrs. Parker and
Rupert Jones, who have kindly furnished me with the materials on which the following
account of it is based.*

* In the tliird series of my " Researches on the Foraminifera" ('Phil. Trans./ 1859), I described
under the name of Amphistegina Cumbigii what I am now convinced to be a Nummuliiia, since it is not
only perfectly symmetrical, but is destitute of the " astral lobes" which characterise all true Amphistegina.

31

242 FAMILY NUMMULINIDA.

421. Krteriial Cliaracters. — The shell of Ampldstegina closely corresponds in external
form with that of Nmuiudlna ; but it is only for some of the smaller Nummulines that Am-
jjliisfi'f/ina could be mistaken, since its diameter seldom exceeds l-8th of an inch, which is
not uncommon among the larger RotaUnes. When viewed from either side (Plate XIII,
figs. 22, 23), it presents an almost exact circular outline, its spiral growth not much affecting
the regularity of the curvature of its margin ; this is partly due to the fact that its chambers
are very numerous, and the increase of their size p^radual, and partly to the peculiar direc-
tion of its septa (iig. 25). In certain varieties, however, the later chambers thin-out and
extend themselves rather suddenly, so that the primordial segment loses its central position,
and the entire shell becomes ear-shaped. When viewed edgeways, the shell presents a form
somewhat resembling that of the crystalline lens in the unequal curvature of its two surfaces,
but having a more acute margin, as is well seen in vertical section (fig. 2G). The under
side, that is, the one on which the aperture presents itself, is normally the most prominent ;
but frequently there is very little diflTerence between the curvature of the two faces ; and some-
times even it happens that the general convexity is greatest on the upper side, whilst the
surface of the shell so sinks in around the umbilical " boss" on the lower side, as to render it
" circumvallate." On the other hand, the upper surface may be nearly flat, whilst the um-
bilical portion of the lower surface becomes very prominent ; so that the general form of the
shell, like that of Botalia Schroeteriana, comes to resemble that of a Conns. Occasionally, though
rarely, the shell is more or less curled or twisted, and may even become saddle-shaped, like
certain individuals among Nummidina and Orbitoides. As, in conformity with the general plan
of construction of the Nwmmulinida (^ 414), each convolution normally invests the whole of
the preceding, only the last convolution for the most part is visible on the surface of the
shell. On looking at its upper side (fig. 22), we see the subjacent septa marked out by lines
of a different texture from the rest of the shell, which proceed in a nearly radial direction
(though slightly curving forwards) until within a short distance of the margin, and then
suddenly bend backwards. On the under side, however, the lines which radiate from
the centre are interrupted at a short distance from the margin (fig. 23), returning as
it were upon themselves, whilst the marginal backward-curving lines in Uke manner
seem to return upon ;'//««selves, thus apparently marking out two sets of chambers
which slightly iuterdigitate with one another. The centre of each surface is occupied
by a large "boss " of non-tubular shell-substance, which is so pellucid as to allow
the subjacent structure to be distinctly seen through it. The contour of this boss is com-
monly " flush" with the general curvature on the upper side (fig. 26, h), whilst on the low^er
side {1}) it is more prominent. When a vertical section of the shell is examined, each boss
is seen to have its origin from the surface of the primordial chamber, and to increase in
diameter with every new overgrowth which this receives, so that it comes to acquire a pretty
regular conical shape. Hence, as the central terminations of the chambers of each whorl
usually stop sliort of those of the preceding whorl, the. latter can be seen to project beneath
the former, so that the whole series of these central terminations may be traced inwards
from those of the latest to those of the earliest convolution. This is more constantly to be
seen on the upper surface than on the lower ; as it is on the former that the alar prolonga-
tions of the later whorls stop short at the greatest distance from the centre. Sometimes,
however, the alar lobes of the later segments extend nearer to the centre than do those of the

GENUS AMPHISTEGINA. 243

earlier, so as partially or even entirely to conceal the central boss ; and there is occasionally
an apparent interdigitation between the alar lobes of successive wliorls, arising out of diffe-
rences in the extent of their central prolongation. This appearance is sometimes seen also
on the under surface ; but as the alar lobes of that side much less frequently stop short of
the centre than they do on the upper side, those of each whorl usually conceal those of the
preceding. — The position of the aperture and the direction of the septal plane in Ampldstegina
constitute very marked features of differentiation from the ordinary Nunmiuline type, and of
approximation to the Rotaline. For whilst in X/ninimlina and its immediate allies, the septal
plane is at right angles to the median plane of the spiral, and the aperture is a narrow fissure
between its inner margin and the edge of the penultimate convolution, the septal plane of
AnipJmfet/ina is very oblique, making a very obtuse angle with the under surface of the shell
nd an acute angle with the upper, and it adheres closely to the penultimate convolution
from its margin to its upper umbo, separating from it on the lower side at about one-third
of the distance between the margin and the lower umbo, so as to form a much wider and freer
opening than exists in the typical Nummuhnes. Thus, whilst the proper Nummuline aperture
belongs equally to both sides, the Amphistegine aperture belongs exclusively to the lower side,
as in the Rotaline group. The septal plane is differentiated in texture from the ordinary
chamber-wall, being destitute (except near its margin) of the fine tubularity by which the
latter is characterised ; but it is usually perforated by a few large " orbuline" pores.

422. The ornamentation of the proper surface of the shell by exogenous deposit consti-
tutes a very peculiar feature of this type. The septal bands are often rendered " limbate"
by rows of tubercles composed of non-tubular shell-substance ; and a smooth deposit of the
like substance along the margin often forms a sort of projecting keel. The general surface fre-
quently receives an investment of the like character, which may be composed of very minute,
closely-set granules, or of larger and more separated tubercles ; this may cover the whole of
each lateral surface, but if restricted to one portion, it is found rather upon the older than
upon the newer segments ; and such an investment is so constant upon that portion of the
under side which lies nearest to the aperture, that its presence there is one of the ordinary
characters of this type, the surface being crowded with granulations which are generally
arranged in rows, and sometimes melt into ridges, whose direction is transverse to that of the
septal bands. The outer surface of the septal plane is itself very commonly ornamented (as
in many Biscorbina) by tubercles, tears, or ridges, of clear substance, which are arranged in
lines that pass from the apex to the base of the plane, and which often so project over the
low-arched aperture as almost to divide it into a line of pores (fig. 24). In some of the conus
shaped fossil Awp/iistef/incs from St. Domingo, the upper (flat) surface presents several large
tubercular masses, each about equal to an ordinary upper " boss."

423. Internal Sfrucfure. — Although most of the principal features of the organization of
Amj]Jii!if('(/iiu( may be made out by transparent sections of tlie shell taken in different directions,
yetthere are others which such sections altogether fail to elucidate ; and it is fortunate for the
true comprehension of these, that we have the additional means of information afforded by
" casts" of the interior of the chambers (see p. 10). Turning our attention in the first instance
to the vertical section which is represented in Plate XIII, fig. 26, we observe a very marked diffe-

244 FAMILY NUMMULINIDA.

rence in tlie convexity of the upper and the under surfaces, and in the position of the primordial
chamber in respect to each ; and this difference is due in part to the gradual declination of
the spire along the plane traversed by the line g, h, and in part to the excess in the growth of
all the parts below that line as compared with that of the parts above it, this being apparent
not merely in the size of the cavities, but also in the thickness of the layers of shell by which
they are separated. It will be observed, moreover, that whilst the alar lobes {a, a) of the
upper sides thin-out rapidly as they approach the centre of each convolution, those of the lower
side [a, a^) thin-out much more slowly, and are often continued as far as its centre. The
shell is finely-tubular, like that of Eotalia, Operculum, and NiimmitHna ; and is composed
of several lamellre superposed one on the other, the tubuli being continuous throughout.
At the umbonal portion ib, b'^,) of each surface, however, the tubuli are deficient, the
shell-substance being there quite pellucid ; and the same condition usually presents itself at
the margin {c, c^ c", c') of each convolution. A very considerable difference presents itself
between the thickness of the chamber-walls of the last convolution {e, e^) and that of the pre-
ceding {d, (P) ; and this will presently be found to depend, as in Calcarina, upon an exogenous
shell-growth superimposed upon the proper chamber-walls ; such increase, however, being made
by the successive addition of laminae exactly corresponding in structure to the original one, and
so perfectly continuous with it and with each other that the pseudopodial tubuli may be traced
■without the least interruption througli their entire thickness. This section further shows the
position of the aperture (/,/^) entirely below the marginal plane of each convolution ; and it
exhibits also the projection of the tubercles formed by exogenous deposit upon the older parts
of the surface, into the cavities of the chambers by which that surface subsequently comes to
be invested. At i is shown an apparent subdivision of the outer wall of tlie convohition, so
as to form a small additional chamber outside the principal one ; but it will be found, when
the vertical section is compared with the horizontal (fig. 25), that this apparent subdivision
is due to the remarkable backward curvature of the septa, whicli often causes sections that
are taken in a radial direction to traverse the inner portion of one chamber, and the outer
portion of another chamber of the same convolution.

424. Owing to the turbinoid form of the spire, a section through any horizontal plane
cannot traverse more than one convolution in its median plane, and must pass either above or
below the median plane of the rest. The horizontal section shown in fig. 25, passes through
the median plane of the outer convolution ; consequently it lays open the penultimate convolu-
tion along its under side ; and it passes altogether beneath the interior convolutions. The
remarkable backward curvature of the septa, by wliich every septum glides (so to speak) into
the periphery of the convolution, along which it is continued, is a very distinctive feature in
this type ; the continuity of the shelly lamina formed at each increase over the whole of the
surface previously exposed, being made evident by the regularly progressive increase in the
thickness of the peripheral layer from the newest chamber to the earliest of the same convolu-
tion. It is a very peculiar feature of this type, that its septal lamellae are not double, as in
the proper Nummulines, but single, as in the lower Rotalines ; so that each chamber is a
" tent " set upon the exterior of the preceding. At the inner margin of certain septa, we
see that they stop short of the wall of the previous convolution ; this being where the
plane of the section has happened to pass through the aperture. Tiie anterior surfaces of the

GENUS AMPHISTEGINA. 245

septa, like the margins of the enclosed whorls, are seen to be studded with large tubercles,
which project into the cavities of the chambers. In the central portion of the section arc seen
the indications of the converging prolongations of the septa, which are interposed between
the alar lobes of the under surface. In those portions of tlie inferior chamber-wall which have
not been removed by the section, we see the general surface minutely studded with the
orifices of the pseudopodial tubuli, which are considerably larger on the inner surface than
they are on the exterior ; these, however, are wanting in tiiose parts that underlie the
tubercles of the surface, which are always composed of non-tubular substance (fig. 25, a).

425. Nothing is shown either in vertical or in horizontal sections to explain that peculiar
disposition of the septal lines which has been already stated to present itself upon the under
surface of the shell; and this might have remained without adequate elucidation, but for the
fortunate accident which has placed in the possession of Messrs. Parker and Rupert Jones the
means of obtaining internal casts of the cavities of this shell in silicate of iron. These casts
so perfectly represent the form of the sarcodal segments which occupied the interior of the
chambers, that their surfaces are rendered hispid by the minute projections which passed into
the entrances of the tubuli of the chamber-walls. On looking at the upper side of one of these
casts (fig. 27), we see, as we should expect, the "alar lobes '' prolonged inwards from the anterior
portions of the peripheral lobes or "bodies" of the successive segments, and gradually narrowing
towards the centre, which they do not quite reach. But on looking at the under side (fig. 28),
we observe that the peripheral bodies of the segments only fold over that surface for a
short distance, and then suddenly round themselves off; whilst the place of their alar pro-
longations is occupied by a set of " astral lobes," which interdigitate in a very peculiar
manner with the bodies of the segments, and send extensions peripherally to the very margin
of the spire. Although, at first sight, these astral lobes appear to be altogether disconnected
from the bodies of the principal segments, yet, on a careful scrutiny of the most perfect casts,
we find that the peripheral extension of each astral lobe is continuous with the retral extension
of the body of the segment that lies in front of it, as shown at a, u ; this continuity being
sometimes established by a thick neck, and sometimes by a very slender peduncle. Hence it
is obvious that these " astral lobes " are nothing else than the alar prolongations of the
chambers on the under side, each being pinched oif (so to speak) from its principal segment
by the intervention of a septum, and being also somewhat displaced backwards.

426. We have seen that the surface of the shell in the neighbourhood of the aperture
so commonly becomes studded with tubercles of exogenous deposit, that their presence may
almost be regarded as among the characteristics of this genus ; and since, as each new chamber
is formed, the tuberculated surface is received into it, and a new exogenous deposit takes place
beyond, every chamber will thus exhibit a projection of these tubercles into its interior.
Now it commonly happens that this deposit extends from the margin towards the centre of the
shell, so that the floors of the alar prolongations of the chambers become studded with
tubercles ; these are sometimes small and closely set without any particular arrangement,
whilst in other instances they are fewer and more prominent, in which last case they are very
commonly arranged in radial lines. These varieties are very beautifully marked in the
"casts" of the alar and astral lobes. In some instances the inner surface of these lobes is

246 FAMILY NUMMULINIDA.

honeycombed with minute depressions, which do not extend, liowever, veiy far into their
thickness ; whilst in other cases each lobe is divided for a great part of its length into two,
three, or even four, narrow bands, connected with each other at intervals, so that the whole
lobe has the character of a network, the meshes of which are occupied by the tubercles or
elevated lines of shell-substance (Plate XIII, fig. 29). These tubercles or lines, rising through
the whole thickness of the alar lobes, join themselves on, like the septa between the lobes
themselves, to the spiral lamina; and, as they consist of non-tubular shell-substance, there are
no tubuli to pass on into the portion of the spiral lamina which overlies them ; and thus their
position is marked on its surface by clear lines, usually more or less interrupted, which inter-
vene between those that mark the position of the subjacent septa (fig. 22). The alar lobes
often communicate with those adjacent to them by connecting bands of their own ; and it
sometimes happens, especially in specimens in which these lobes are most broken up, that
these communications are almost as numerous as those uniting the different bands of the same
lobe ; so that the portion of the sarcode body covering the lateral surface of the shell forms
one continuous network, in which the division into alar lobes is scarcely distinguishable.
This varietal modification is of peculiar interest, as representing in this type the still more re-
markable modification of the alar prolongations which we shall find to be characteristic of
certain forms of Nummulina (^ 462).

427. The various forms of AmpMstefjina which have been ranked as distinct species differ
from each other only in characters which our extended study of this group has led us to
regard as non-essential ;• — such as the degree of convexity of the shell in proportion to its
diameter; the amount of inequality between its two lateral halves; the amount and kind of
exogenous deposit on its surface ; the number of chambers in each whorl, and the proportional
distance between their septa ; the degree of backward curvature of the septa of the marginal
portion of the convolution ; and the mode in which the astral lobes of the under side are
intercalated between the marginal segments. The differences in all these particulars which
may be presented by individual specimens, arc found, when large numbers are examined, to be
so gradational, that no definite lines of division can be drawn between them. In point
of size, there would seem at first sight to be a marked distinction between the recent
and the fossil examples of this genus ; for whilst the diameter of the former does not
ordinarily exceed 1-1 4th of an inch, and is often not more than l-20th, that of the latter some-
times attains l-7th of an inch. This difference, however, no more constitutes a valid specific
distinction, than do any of the preceding ; for I have recent specimens from the Philippine
seas, which attain a diameter of 1-lOth of an inch, and which are yet unquestionably of the
same type with the ordinary examples of not half their diameter.

428. Affiniiies. — From a comparison of the preceding description with the account of the
Rotaline type given in the preceding chapters, it will be evident in what particulars Ampliisfe-
fji'iia presents the characteristic features of that type. The turbinoid spire, the consequent
inequality of the upper and under sides, the limitation of the aperture to the under side, and
the obliquity of the septal plane, are all Rotahne peculiarities ; the singleness of the septal
lamella: is a most important additional hnk of affinity to that group, and so also is the distinct-
ness of the " astral lobes," which specially links An/ji/iisfc^ina to Itotalia (% 371). All these

GENUS OPERCULINA. 247

peculiarities, whilst they indicate the relationship of Amphistegina to the Rotalines, differentiate
it in the like degree from the Nummulines. To the latter group, however, it presents so close a
conformity in the texture of its shell, in the complete investment of each convolution by that
which succeeds it, in the presence of alar lobes upon its upper as well as on its under surface,
and in its general tendency to bi-lateral symmetry, that we cannot hesitate in considering
it as most nearly related to tlie Nummulines ; its special affinities being to Nummlina its
general plan, and to the simple "nonionine" Poli/stomella in the exogenous deposit whicli
forms its umbilical "bosses." It may thus be considered in the light of a Nummuline
degraded to the Rotaline level ; just as the true BotaJia is a Rotaline elevated to the Nummu-
line level, so as to stand, in grade of development, considerably higher than Amplmtegina.

429. GeofjrapJiical and Geological Distribution. — The range of this type through tropical
and sub-tropical regions appears to be very general, as it has been found in various parts of
the Indian Ocean, the great Polynesian area, and the West Indian seas ; the furthest limits to
which it is known to extend northwards are the Red Sea and the neighbourhood of the Canary
Islands ; while southwards it has not been traced further than New Zealand. It occurs in
greatest size and abundance at depths of from 15 to 50 fathoms ; but small specimens have
been brought up from abyssal soundings in the Red Sea. No true Amphistegina has yet been
discovered earlier than the Tertiary epoch ; and this genus does not seem to have become
abundant until after the period when the proper Nummuline type attained such an extra-
ordinary development, presenting itself especially in the Miocene and Pliocene deposits of
Bordeaux, Vienna, San Domingo, the Sub-Apennine group, Virginia, South Carolina, Alabama,
and New Zealand.

Genus II. — Operculina (Plate XVII).

430. Historg.— The genus Operculina was first created by D'Orbigny (lxix) for the recep-
tion of a type of Foraminiferous structure allied to N'lmmulites, but definitely (as he considered)
differentiated from it ; examples of this type, however, had been previously described by
Gronovius (l) and Schroter (xcv) under the generic designation A^autilus, and by Basterot
and Defrance (xxix) under that of Zenticulites, a name which has been applied to such a great
variety of dissimilar organisms that it cannot with any propriety be retained. According to
D'Orbigny (lxxiii), Operculina is distinguished from Nummulina by the extreme compression
of its discoidal shell, by the smaller number and more rapid increase of its whorls, by tlie
non-investment of the earlier whorls by the later, so that the former remain apparent on
both sides through the whole of life, and by the form of the aperture, which is a transverse slit
in Nummulina but triangular in Operculina. The genus, as characterised by D'Orbigny, has
been adopted by -many subsequent systematists, as Bronn and Pictet ; and it is also admitted
by D'Archiac and Haime (i), who, however, seem to have clearly perceived the fallacy of
D'Orbigny's description of the convoluiions as non-embracing, and of the aperture as
triangular, since they consider it to be distinguished from Nummulina only by the depression ot
its form, the small num.ljer of its convolutions, and the rapid increase in breadth of the last
whorl, which (according to them) constantly remains open, whilst that of Nummulina always

248 FAMILY NUMMULINIDA.

tends to close in. As I shall show hereafter, I cannot admit the validity of the last distinction ;
and the difference between Operculina a-nd Nummulina comes to rest only on the general form
of the spire and the conspicuousness of its convolutions, — characters which seem by no means
sufficient for the separation of the former as a genus distinct from the latter. As, however,
they mark a difference in the respective physiognomies of these types which enables them to
be at once distinguished by their external conformation, it seems for the present desirable to
retain Operculina as a generic type ; more especially as it is very generally diffused at the
present epoch, whilst Nummulina proper is almost extinct.

431. The minute structure of this type had been investigated by two excellent observers
previously to the appearance of my own description of it (XA'). Under the designation of
"an undescribed species of Nonionina^' VvqI. Williamson gave an account (cviii) of the
structure of a shell abounding in the Manilla sand, which, not merely from his figures and
descriptions, but from a comparison of the specimens which he has kindly enabled me to
make, I know to be one of the smaller forms of the Philippine Operculina. Mr. H. J. Carter
(xviii) still more minutely described the organization of an Operculina which he obtained in
great abundance on the south-east coast of Ai-abia, the shells coming up attached to the
grease of the sounding lead from sandy bottoms of between ten and twenty fathoms
depth ; and of the identity of this with a larger form of Philippine Operculina I am enabled
to speak, from an examination of specimens which Mr. Carter has obligingly transmitted to
me. Tiie rich store of material placed at my disposal by Mr. Cuming from his Philippine
collection, not only enabled me to prosecute my inquiries into the minute structure of this
organism upon specimens of unparalleled size and degree of development, but also enabled
me to bring together a great body of data for comparison as to the extent of variation which
it may undergo, alike in external conformation and in internal organization. And as the
information hence obtained has a most important bearing upon the study of the closely-allied
genus Nummulina, I consider it desirable to go into more minute detail on this point than
would be otherwise accordant with the general character of the present treatise.

432. E.rternal Characters. — The shell of a fully developed Operculina of the ordinary type
(Plate XVII, fig. 1)* is a compressed spiral of about •25 inch in diameter, and about 015 inch
in thickness, consisting of between three and four convolutions gradually increasing in breadth ;
these are in general nearly flat, but are sometimes a little arched between their inner and
outer margins, and are sometimes depressed so as to present a slight concavit)', especially
near the outer margin of the last whorl. The chambers are about seventy-five in number,
commencing from a primordial spheroidal cell, and progressively increasing in dimensions with
the widening of the spire ; their septa have for the most part a radial direction, but they bend
backwards near the outer margin of each whorl ; and they are marked externally by bands
which are distinguished by their semi-transparent aspect from the dull brownish hue of the
general surface. These septal bands are commonly on the same plane with the intervening
portions of the shell ; but sometimes the walls of the chambers are a little arched between

* For the better display of tlie internal structure, the ideal figure has been constructed on the
model, not of the ordinary compressed Operculina, but of a variety with a more turgid spire.

GENUS OPEllCULINA. 249

the septa that bound them, so that the septal l)an(ls arc slightly furrowed ; whilst the
walls of the chambers arc sometimes a little depressed, so that the septal bands arc
prominent ; and such varieties may present themselves in different parts of one and the
same shell. Not unfrcquently the whole surface is seen to be marked by very minute
punctations ; luit more commonly they are larger and fewer in number, and are often
arranged in pretty regular lines parallel to the septal bands, — one, two, or three rows of such
punctations being seen on the wall of each chamber : these punctations, which often present
themselves abundantly on some parts of the surface, whilst they are entirely absent from
others, are found, when sufficiently magnified, to be spots of semi-transparent shell-substance
resembling that of the septal bands ; and, as in the case of these, their surface is sometimes
on the same plane with that of the general surface of the shell, sometimes a little elevated so
as to form papilkc, and sometimes a little depressed into minute fossae. Sometimes, instead of
a limited number of comparatively large and regularly arranged punctations, we find a vast
number of very minute papillae, scattered without order over the entire surface of the
chambers ; these, again, may be absent from some parts of a shell over other portions of
which they are abundantly distributed. There is commonly a large semitransparent tubercle
at the umbilicus, and smaller tubercles are often seen along the septal bands, especially of the
earlier whorls : not unfrcquently, however, the umbilicus is depressed instead of being elevated
into a tubercle, and the moniliform tubercles along the septal bands are wanting.

434. The departures from this typical form, however, are very wide. A glance at any
considerable collection of specimens reveals to us an extraordinary variety not merely in size
but also in proportion ; and our attention is first attracted by a series which are not only
distinguished by a size greatly above the average — their long diameter reaching nearly4-l0ths
of an inch, — but also by the extraordinary flattening of the later convolutions, and the rapidity
with which the spire opens out. The approximation between the two lateral walls of the
chambers is here so close, that not only are the septal bands rendered very prominent by the
depression of the lateral surfaces between them, but even the outer marginal band stands up
as a ridge from which the walls of the chambers slope down. In fact, an examination of
this form leaves the observer impressed with sui-prise that any room can be left for the
animal, the segments of which must be extraordinarily attenuated, losing in thickness what
they gain in area. Now a careful comparison of this form with the ordinary type, not only
makes it obvious that the former difi'ers from the latter in no other particular than this attenua-
tion, which (as already pointed out in the case of Pcneroplis) is a common feature of the
later growths in Foraminifera, but also that the attenuation takes place in such difl'erent
degrees in different individuals, that any attempt to use it as a differential character is com-
pletely baffled by the continuous gradation of forms which is presented between the one
assumed as the typical and such as most widely depart from it in this particular. Among the
smaller Philippine specimens, on the other hand, a very different configuration is presented.
In those whose diameter docs not exceed 1-lOth.of an inch, the spire, instead of being flat,
or even somewhat hollowed, is often so highly arched between its inner and its outer margins
that the breadth of the septal plane is equal to its length or nearly so ; and a like turgidity, to
the degree represented in Plate XVII, fig. 1, sometimes shows itself in specimens of nearly
twice that dimension. This variety of conformation, however, being limited to shells whose

32

250 FAMILY NUMMULINIDA.

earlier period of growth is evinced by their smaller number of convolutions and of chambers,
and beinf^ often seen, moreover, in the earlier whorls of those which afterwards present the
greatest flattening, may safely, I think, be regarded as partly a character of age. It will be
recollected that the young of the flattened Fencropl'iH often resembles BendrUina in the com-
parative turgidity of the spire (1[ 130) ; but I do not find that Operculum ever continues long-
to increase upon such a plan ; for the compression af the spire always shows itself in the third
whorl, if it has not previously done so, and is accompanied with a corresponding augmenta-
tian of its breadth, so tliat the septal plane becomeh' narrowed in Fig. XL. Such a section
makes it obvious that no basis for specific distinction can be afforded by the most marked
differences in the form of the spire, as shown in the proportions of the septal plane ; since
differences equal to those presented by the most compressed and the most turgid forms of the
spire are there exhibited by the successive convolutions of one and the same individual.

435. Another marked feature of difference to be noted among individual OpercuIuiah^Q
depression or elevation of the central region relatively to the peripheral. In what I have as-
sumed as the typical form, the central region presents the same general level with the rest, though
the umbilicus itself is often marked by a prominent tubercle. In young specimens with a turgid
spire, however, the umbilical region is rather depressed than elevated ; and tiiis depression
is often observed in older specimens whose early growth has taken place on this type. But a
form is not uncommon, in which the whole central region is so exceedingly prominent as to
form a cone whose apex is marked either by one large tubercle or by a cluster of smaller
ones ; find this conformation gives so peculiar a physiognomy to the shells which present it, that
few systematists would hesitate in placing them apart as specifically different from the rest. On
a careful comparison of a large number of individuals, however, it becomes apparent, that this
difference, like the preceding, is gradational; every degree of prominence being traceable from
the individuals which have the umbilicus marked only by a tuljcrclc, through those in which
the region generally is slightly elevated, to those in which it presents the most marked pro-
minence. We shall presently find (^441) that this difference depends mainly on the degree in
which the investing layer, prolonged from the later convolutions over the surface of the earlier,
is separated from that surface by the extension of the alar prolongations of the chambers of
the investing whorls ; as to which point there is a most remarkable diversity, not only among
different individuals, but between the several convolutions of the same individual.

436. A third very obvious character of differentiation among the individuals of this col-
lection, consists in the presence or absence of tubercles on the septal bands. In wliat I have
described as the typical form, there are no considerable prominences over the greater part of
the surface ; the septal bands are generally smooth and continuous ; and it is only in the
central region that we observe any departure from this uniformity, the umbilicus being occu-
pied by a small tubercle, and the smooth septal bands being replaced in the first whorl by
moniliform rows of little tubercles. In other instances, however, we find not onl}' the central
tubercle, but the rows of tubercles marking the septa, much larger and more prominent ; and
this marking-out of the septal bands by elevated tubercles is not limited to the first whorl, but
may extend to the second, and even to the third. The specimens whose central region is very
prominent usually show this feature in the most decided manner ; but it is occasionally pre-

GENUS OPERCULINA. 251

sented also in no less a degree by those whose umbilicus is flat or even depressed. The most
remarkable departure from the ordinary type is seen in a small group of specimens in which
the tubercles are not only extremely large and prominent, but are distinguished by their
opaque whiteness, which contrasts strongly with the semi-transparence ordinarily charac-
terising these prominences. But even this character has no diagnostic value ; for a specimen
which has the tubercles opaque in one part may have them semi-transparent in another ; and
as to the size of the tubercles, their degree of prominence, and the proportion of the entire
spire over the septa of which they occur, there is every degree of variety. In one of my
largest and flattest specimens, the central region is strongly tuberculated, but the tubercles
almost suddenly cease when the spire begins to open out, and the septal bands are thenceforth
as smooth as in the ordinary type.

437. A less obvious but still very decided feature of individual difference, consists in
the presence or absence of papillary elevations hdwecu the septal bands. I have already
spoken (^ 433) of the frequent existence of symmetrically arranged spots, sometimes slightly
depressed, but more commonly elevated, that are distinguished from the rest by the semi-
transparence of their shell ; these spots are sometimes considerably enlarged, and their elevation
increased, so that they become prominent papilla), closely resembling the tubercles upon the
septal bands. Their size and disposition vary considerably. Sometimes they are small,
numerous, and scattered without any definite arrangement over the entire surface of the wall
of the chamber ; whilst in other cases they arc considerably larger, and form single, double,
or even triple rows between the septal bands. Another remarkable variety of external aspect
is produced by the elevation of the general surface into rounded eminences closely abutting
on one another (like the pustules of the skin in a case of confluent smalUpox), and distin-
guished from the preceding by the absence of any peculiarity in the texture of the shell.
That these and other analogous variations of surface-marking have no value as differential
characters is at once demonstrated, not merely by their gradational approximation in different
individuals, but by the fact that they are presented in very diS'erent degrees on different
parts of the surface of the very same shell ; the chambers of one part of the spire being
strongly marked by certain of these peculiarities, whilst those of another may only present
indications of them, and those of a third may be perfectly smooth.

438. The collection of Mr. Cuming, however, furnished me with a group of forms which
are at once distinguished from the rest by their general physiognomy, and which, when their
characters are examined in detail, appear to be separated from them by well-marked dif-
ferences. Their aspect is much more lustrous, and their hue much whiter, varied, however, by
a tinge of green diffused in irregular patches ; the spire does not in the largest specimens
make above three turns, and it begins to open out sooner than in the type already described ;
the septa are usually considerably more convex anteriorly, and are also rather more distant
from each other, so that the interval between them is greater in proportion to the breadth
of the spire, the shape of the chambers being thus modified, and the number of chambers in
each whorl being diminished ; the septal bands, not merely of the earlier whorls, but even of
the last-formed portion of the shell, are raised into prominent tubercles ; and multiple rows of
large tubercles are seen between the septal bands. It is to this multiplication of smooth

252 FAMILY NUMMULINIDA.

lyi

tubercles, composed of a variety of shcU-substance which reflects light much more strongly
than the rest, that the more glistening aspect of this type is chiefly due ; and I have not met in
it with any instances of that general brownisli coloration of the surface which is the ordinary
characteristic of the other. The most constant and remarkable distinctive feature of this type,
however, is the presence of a large hemispherical cluster of semi-transparent tubercles in the
centre of the spire. — Having had no difiiculty in setting apart a large number of specimens
agreeing very closely with each other, and differing from the rest, in all the foregoing cha-
racters, I should have arrived at the unhesitating conclusion that this type deserves to take
rank as a species of Operculina distinct from the preceding, were it not for the circumstance
that every here and tliere I met with an example in which the di0"erential characters were less
strongly marked than usual. Thus in some individuals which preserve the general propor-
tions of the spire, the green coloration is wanting, the large central cluster of tubercles is re-
placed by a single tubercle of extraordinary size, the septal bands of the neighbourhood are
not more tuberculated than in many examples of the ordinary type, and the rows of tubercles
over the chambers are either wanting altogether, or are not more prominent than in many
individuals of the preceding type. This evidence of the negative value to be attached
to the number or prominence of the tubercles as a specific character, is confirmed by a
curious fact of an opposite nature ; namely, that in certain individuals we find them deve-
loped to an extraordinary and obviously abnormal degree. — From the difliculty of deciding to
which type particular specimens are to be referred, I had been almost led to adopt the con-
clusion of the specific identity of this with the ordinary form ; when Dr. Gould, of Boston
(U. S.), kindly placed in my hands some Opcrcullnce which had been collected on the coast of
Japan by the recent American expedition to that country. These specimens combined in so
remarkable a manner the most distinctive features of the two types, — namely, the general
form and proportions of the one, with the umbilical hemispheric cluster of tubercles and the
general abundance of tubercular elevations characteristic of the other, — as to remove all doubt
from my mind with regard to their specific identity. Similar variations present themselves
among the dwarfed examples of this type which are found on the shores of temperate seas
■ (^450), and also among the fossil forms of it which abound in the Eocene and other Tertiary
deposits. Tlie minute form most common in northern seas has been described and figured
by Prof. Williamson (ex,) under the designation oi Nonionina elegans ; but I fully agree with
Messrs. Parker and Rupert Jones (lxxx h, lxxxi), in identifying this as a varietal form of
Operculina complanata.

439. Internal Structure. — The study of the internal organization of Operculina may be
prosecuted in two modes; — b}' the examination, under sufficient magnifying powers, of thin
transparent sections taken in difi'erent directions ; — and by viewing under a low power, as
opaque objects, fragments obtained by breaking the shell, especially (as Mr. Carter was the
first to suggest) after these have been allowed to absorb carmine or indigo by being placed
upon water in which either of these colours has been rubbed up. By the former method
alone can certain minutise of structure be detected ; but the latter is extremely serviceable in
enabling the observer to trace out the relations of various parts, which sections exhibit to him
disconnected from one another. Owing to the circumstance that large specimens of Opercutiua
are rarely if ever quite flat, it is next to impossible to make a section through the median

GENUS OPERCULINA.

253

plane that shall traverse all the whorls to the central cell; by choosing a sufficiently flat
specimen, however, a sufficiently near approach to this may be made to i)ring into view the
general disposition of the chambers. This is much less regular than would be supposed from
a superficial examination of the exterior. For while there is a certain general average in the
proportion which their long diameter (that is, the breadth of the whorl) bears to the short (or
the distance between the septa) which may be slated as about 4^ to 1, this is by no means
constantly maintained, the long diameter being sometimes as much as 7 times, and sometimes
no more than 2| times, the short. The ordinary course of the septa, too, is often strangely
departed from. There are few individuals which do not present — besides abnormal sinuosities,
greater or less in degree — very marked irregularities in the conformation of the chambers,
analogous to those which occur in Numwulifeii. Frequently a septum, instead of passing con-
tinuously from the inner to the outer margin of the whorl, stops short witliout reaching the
latter, and bends backwards to join the last-formed septum ; and sometimes a second septum
unites itself to the first in the same manner. The abortion is often still more marked ; thus
in Fig. XXXIX we see three septa thus interrupted, of which two do not traverse half the
distance, and the third not a quarter, thus dividing the space between two complete septa into
three small chambers along the inner margin, and one large irregular chamber extending to
the outer.

Fig. XXXIX.

Irregular disposition of septa in Operculinct: — «, a, n, uormal apertures at inner margin of spue; h, b', b", apertures
of communication between abuormallj divided clumbers.

Generally speaking, the more nearly we approach the centre of the spire, the more regularly do
we find the septa disposed, until we come into close proximity with the central chamber. In
Plate XVII, fig. 6, we have an illustration of what may be considered the normal mode of
commencement of the spire ; from which it will be seen that it originates, as in Foraminifera
generally, in a spheroidal cell, from which others are successively developed around it, the
earlier chambers having no very definite shape, but those which succeed them gradually
coming to assume the characteristic form and proportions.

440. Each chamber communicates with the neighbouring chamber on either side, by a
long narrow crescentic fissure left by the non-adhesion of the septum to the outer margin of
the preceding whorl (Plate XVII, figs. 1, 2, e, e, e). This fissure is best brought into view
either by making thin transverse sections (as Fig. XL), or by breaking a specimen transversely
and examining its fractured edges, by which such views will be obtained as are presented in

254

FAMILY NUMMULINIDA.

Fig. XLIII (p. 258), A, B, c, d. Besides this principal aperture, wc observe in the septa, espe-
cially of the larger chambers^ a variable number of " orbuline " or secondary pores (Plate XVII,

Fig. XL.

Vertical or transverse section of three outer
convolutions of OperatUiia.

figs. 1, 3,/;/), generally circular, and of comparatively small size; these are disposed without
any regularity, as is shown in Figs. XL, XLIII. They may or may not be brouglit into view
in a horizontal section, according as its plane does or does not happen to pass through them ; but
when they are thus traversed (Fig. XLI, b, h, b), it is seen that these secondary pores, like the
principal aperture, a, «, establish a direct communication between adjacent chambers. In the

Fig. XLI.

Section of tke two septa of Operculina through the median plane, showing the secondary pores, h, h, h, in addition to
the principal apertures, o, a, at the inner margin of tlie spire.

irregular formation represented in Fig. XXXIX, these secondary pores {h, I', b") present a
disposition which would seem to indicate that they are scarcely less important for the mainte-
nance of the communication between the chambers, than is the principal aperture itself; and
it is curious to observe how exactly they repeat at h' and b" that mode of communication
between two segments on the inner side and one on the outer, which is so characteristic of
Or/j'doUtes and Orbiculinu. These secondary pores may be considered as representing, in the
more elevated type with which we are at present concerned, the multiple pores which consti-
tute the sole communication between the chambers in PeneropUs (1 124). Every septum is
composed of two laminae (Plate XVII, fig. 1, d, d), each being the proper wall of one of the
chambers which it separates; these laminae are commonly in close apposition with eacli
other; but they separate at certain spots, to give passage to the very curious system of
interseptal canals to be presently described.

441. A comparison of numerous vertical sections brings into view a most remarkable
variety in the form and disposition of the chambers, not merely in different individuals, but

GENUS OPERCULINA.

255

in different parts of the same individual. Commencing with one of the flattest variety, Fig.
XLII, c, we observe that the breadth of the septal plane is very small in comparison with its
length ; and that although the spiral lamina of each whorl except the last obviously extends
itself over the preceding whorls, the cavity of the chambers is not so extended, those of each

Fig. XLII.

^ -*JjiiJl!liLL_

Vertical or transverse section of six specimens of Opeicidina, exliibiting marked variations iu the form and proportions

of the convolutions.

whorl being bounded internally by the external margin of the preceding. Passing from this,
however, to forms {c) which are slightly elevated in the centre, we find not only that the
breadth of the septal plane is increased, but that the cavity of each chamber is extended into
two «/^, which are more or less prolonged over the enclosed whorls; so that the spiral
lamina of the investing whorl is kept by their interposition from coalescing with that which
it embraces, except in the central region. The degree of this extension, however, varies in
different convolutions ; the alae being usually smaller in the chambers of each consecutive
whorl, and being absent altogether from those of the last — a transition well shown in Fig.
XL, which also exhibits the marked variation in the general proportions of the chambers that
may present itself between the inner and the outer whorls. In forms which are distinguished
by a yet more turgid spire, the proportions of the chambers are very considerably modified ;
but among these there is a considerable difference in the degree in which the chambers
of the later whorls arc prolonged over the earlier; thus in Fig. XLII, a, whose centre is on a
level with the rest of the spire, and in e, whose centre is elevated, we see the ate prolonged
so as quite to reach that region ; whilst in d and f, which have the central region depressed

256 FAMILY NUMMULINIDA.

(the umbilicus itself being occupied by a prominent tubercle of solid shell-substance), though
the general proportions of the chambers correspond with those of the preceding, the aire are
so little extended that the spiral laminjc of the successive whorls coalesce not only at the
centre, but at some distance around it. — After an attentive examination and comparison of
a large number of vertical sections, I feel justified in affirming that no importance can be
attached to the form and proportions of the chambers, whether shown in the relative
length and breadth of the septal plane, or in the degree in which their al?e are prolonged
over the enclosed whorls, as furnishing characters of specific difl'erence ; seeing that it is not
only found to vary gradationally when a sufficiently large series of specimens is compared, but
that it is often equally inconstant in different parts of the same individual.

442. The spiral lamina, in typical specimens, is much thicker in the inner than in the
outer convolutions, that of the last whorl being always comparatively thin (Fig. XL) ; and a
careful examination of transparent vertical sections makes it apparent, that the greater thick-
ness of the spiral lamina of the earlier whorls is partly due to the prolongation of that of the
later whorls over them, and to its coalescence with them. I have not been able to satisfy
myself that the spiral lamina of the last whorl is thus extended over the preceding whorls;
and it has rather appeared to me to be merely applied to the margin of that which it surrounds.
The difficulty of certainly determining this point chiefly arises from the circumstance that
the spiral lamina of the last whorl is reduced in thickness in proportion to its extension, as if
in consequence of a limitation of the amount of calcareous matter employed in its formation.
The spiral lamina is made up of a variable number of lamellre of minutely-tubular substance
(1 58) ; and its tubuli may be traced continuously through all its lamellie, as shown in Plate
XIX, fig. 3. In examining extremely thin transverse sections of this tubular shell-substance
with a sufficiently high magnifying power, I have been able to perceive that the orifices of the
tubuh are separated by a very delicate areolation (Plate XVII, fig. 9), as if the whole substance
were composed of an aggregation of prisms with a tubulus in the centre of each, as is shown
under a still higher magnifying power at fig. 8, a ; and this accords well with the idea that
each prism is really a hollow spicule (like that of Amnihomctra, 118), formed around one of
the pseudopodia. The diameter of the tubuli is greater at and near the inner surface of the
walls of the chambers than it is at a little distance from them, as will be seen by comparing
fig. 1 3 of Plate XVII with fig. 12; so that when a thin lamina from the innermost part of
the wall is examined under a high magnifying power, the tubes are seen almost to fill the
areolae, as is shown in fig. 8, b, which is drawn on the same scale as a.

443. The shell-substance over the septa is not penetrated by tubuli, and is consequently
far more transparent than the rest ; and it is in consequence of this difference in texture, that
the septal bands are so strongly marked on the external surface, as well as in sections parallel
to it (Plate XVII, figs. 12, 13, aa, a' a). The same is true, also, of the substance of the
tubercles, whether occurring as elevations of the septal bands, or upon intermediate parts of
the spiral lamina. In the latter case, the tubercles are seated upon inverted cones of the like
substance, which do not usually reach down to the inner lamina, so that the internal surface pre-
sents the orifices of the tubuli regularly disposed over the interior of the chambers (as
seen in fig. 13), even where sections passing at a little distance from these show rounded or

GENUS OPERCULINA. '_>:;7

elongated spots of transparent substance (fig. 12, b, /A, around wliicli the tubuli arc crowded
together, as if they had been displaced by its interposition. Such spots occasionally present
themselves in the ordinary type of Opercitlhui ; but it is of course in sections of the strongly
tuberculated variety that we find them most marked, and this especially in the investing
layers of the central region, where, from the size and upproximation of the tubercles, the
spaces between them are rendered almost opafpie by the crowding together of the tubuli. The
tubuli are generally seen, moreover, to be somewhat more crowded in the neighbourhood of
the septal bands. The greatest local development of the non-tubular substance is seen in
those varieties which have a large elevated tubercle in the centre ; a section of such a variety
has been shown in Fig. XLII, d, where it is seen that this tubercle springs from the spiral
lamina of the innermost convolution, but that it increases in diameter as it is built-upon (so
to speak) by each of the whorls by which this is subsequently invested.

444. The texture of the shell-substance which bounds the chambers at the outer margin
of each whorl (Plate XVII, fig. I, a, a), however, presents a marked departure from that of
the spiral lamina ; a difference analogous to that which was first indicated by me in iSnmmu-
I'lles (xii), and which has been found by MM. D'Archiac and Haime (i) to present itself so
constantly in that genus, that they give to this marginal portion the special designation
"bourrelet." The speciahty in the structure of this part of the shell of Opercnlina was
recognised by Mr. Carter (xvii), who described it as made up of an aggregation of fusiform
spicules, and hence designated it as " the spicular cord."* Now I am very familiar with the
appearance which has led him to take this view of its nature, since it is one which is commonly
presented by thin sections that pass either through the median plane or parallel to it, as shown
in Plate XVII, fig. 3, «'" a"; but this is only one out of many aspects which are presented
by sections taken in various directions ; and a comparison of the whole seems to me to
lead to quite a different conclusion, — namely, that the supposed spicular composition of this
" marginal cord " (as it may be appropriately termed) is due to the peculiar manner in which
the homogeneous substance of which it is composed is traversed by the set of canals that are
correctly described by Mr. Carter as forming the " marginal plexus." For if the section
should happen to traverse a portion of this plexus in which the canals form a tolerably regular
network of elongated meshes in one plane, the appearance delineated in fig. 3 is pre-
sented ; but just as often a less complete layer of the network is traversed by the section,

* Mr. Carter !ias recently (xxiii a) criticised my account of the structure of the " marginal cord,"
and has re-stated his reasons for persisting in his original account of its "spicular" structure. So fiir
from finding in tliis latter statemeut any reason for modifying my own views, I draw from it additional
reason for believing that Mr. Carter has been misled by the results of the metliod of examination on
which he seems to place most reliance ; since by " cutting off taugentially portions of tliis cord with a
small sharp scalpel," lie must have almost necessarily found his sections frittered into the semblance of
an aggregation of spicules. The true structure of the cord is much more certainly shown by sections
made in various directions, and carefully reduced by rubbing down wliilst attached to glass; of such
sections I have numbers in ray possession. It may be well for me to add that MM. D'Archiac and
Ilainie have been equally unable with myself to admit the correctness of Mr. Carter's interpretation of
the appearances he has witnessed.

33

258

FAMILY NUMMULINIDA.

and the form of the meshes is very inconstant, so that the appearance presented is rather
that shown in fig. 4. Moreover the appearances exhibited by transverse sections of this
marginal cord, highly magnified (fig. 5, a a), do not at all confirm the idea of a spicular
arrangement, hut are altogether conformable to the view I have expressed ; the most complete
confirmation to which is afforded by tangential sections, of which a very successful example,
— giving a beautiful view, not only of the canal-system of the " marginal cord," but also of
its communications with that of the septa, and of its relations M'ith the two principal spiral
canals to he presently described,- — is represented in fig. 7, a, a. In this it is clearly
seen how irregular is the disposition of the inosculating passages, whilst there is not a
trace of the spicular structure, which ought, if it existed, to be as well brought into view in a
section taken in this direction, as it is in the one shown in fig. 3, which is takeii in a plane
at right angles to it. The " marginal cord " is traversed on its external surface by longitu-
dinal furrows, which are sometimes very shallow (fig. 5), but sometimes dip down deeply like
those between the convolutions of the brain. These furrows usually form a kind of network
with fusiform interstices, whilst in other cases they run parallel to each other and inosculate
rarely. From the correspondence between their arrangement and that of the passages in the
interior, I am inclined to think that they belong to the same system with these, being, in fact,
canals not covered in by shell-substance, that communicate with the plexus within by
inosculating branches, whose apertures may sometimes be detected in the bottom of the furrows.

445. The " marginal plexus " of canals communicates freely with the system of " inter-
septal canals" (Plate XVII, fig. \, <),(/), which are disposed between the two layers of the
septa. The distribution of these is well seen, not only in vertical sections which have
happened to traverse the septa as in Figs. XL, XLII, and in Plate XVII, fig. 7, but also
in specimens laid open by fracture in the same direction, especially after the canals have
been more distinctly marked out by the imbibition of a colouring liquid (Fig. XLIII, and

Pig. XLIII.

Septal planes of four specimens of OpcrcuUiia, showins); varieties in the disposition of the iiilerscptal canals.

GENUS OPERCULINA, 259

Plate XVII, fig. 2). It will be seen from these delineations, all of which arc faithfully copied
from specimens in my possession, that the distribution of the interseptal canals, whilst presenting
a certain general uniformity of plan, is by no means constant in detail. In Figs. XLII, a, and
XLIII, D, we see two principal trunks passing from the two angles of the fissure at the interior
edge of each septum to join the marginal plexus at its exterior (as shown in Plate XVII, fig. 4),
and sending out branches which ramify over the part of the septum that joins the spiral
lamina (Fig. XLIII, d), leaving the intervening portion untraversed. But in Fig. XLII, a
(as in Plate XVII, fig. 2), we observe two or more such trunks proceeding from each angle
of the fissure, those of the same side frequently inosculating with each other; in Fig.
XLIII, c the two principal trunks on the opposite sides inosculate as they approach one
another in their course towards the outer margin of the septum ; and in Fig. XL this inos-
culation is seen to take place much nearer the inner margin of the septum of the last whorl,
so that the greater part of the septal plane is occupied by the plexus formed by their inter-
lacement. The interseptal canals of one septum are occasionally, if not invariably, connected
with those of another, by loops formed between the ramifications of those canals which
extend along the alar prolongations of the septa towards the centre of the shell. Moreover,
branches of the same system are generally found to penetrate the non-tubular shell-substance
whenever it accumulates in any quantity ; these branches are at once distinguished from the
ordinary tubuli (as in fig. 12, Plate XVII), by their much larger size, their diameter being
commonly about 1 -5000th of an inch. Those which proceed towards the spiral lamina
sometimes pass towards the surface in the non-tubular shell-substance that constitutes the
septal bands, as is shown in Fig. XLIII, d, and in Plate XVII, fig. 1 ; they are also frequently
seen to diverge from the septa over the walls of the chambers, — still, however being usually
invested by a layer of transparent shell-substance, as is shown in Plate XVII, fig. 4. This
last figure represents an appearance of areolation I have several times met with in the walls
of the chambers, — though usually less conspicuously than in this instance, — which has made
me suspect that the ramifications of the interseptal canals sometimes (if not as a regular rule)
form a network in the spiral lamina over the entire surface of the chambers.

446. The interseptal system of each whorl is connected with the marginal plexus of the
preceding by a very remarkable arrangement. At each junction of the marginal cord with
the tubular substance of the spiral lamina, the orifice of a large canal (Plate XVII, fig. 2,
/.', //) may be seen in a vertical section which divides this canal transversely ; and either of
these canals (fig. 1 , //, h,) may be clearly traced in sections parallel to the surface that have
happened to pass through its plane, as at //, //, fig. 6, in which, by a fortunate accident, one
of the spiral canals has been laid open in its entire course through the inner whorls, and can
be traced nearly to the central chamber. In the tangential section, fig. 1 0, the two canals
n, a', can be seen running on the outside of what may be called the iiurJeus, consisting of the
central chamber and the chambers immediately surrounding it. The branching-off" of the suc-
cessive interseptal passages from these two spiral canals, is shown in fig. 6 ; and the relations
of the different parts of the system are brought extremely well into view in fig. 7, which
represents a tangential section of a young shell, the rapid curve of whose spire causes the planes
of even the contiguous septa to vary greatly in their direction. The spiral canals //, //, though
only running along the angles of the marginal cord, as shown in transverse section at fig. 5, //, li ,

260

FAMILY NUMMULIINIDA.

pretty obviously communicate with the plexus of passages which it contains ; and thus the
interseptal system of one whorl is brought into direct connexion with that of the preceding.
It is to be remembered, however, that independently of such connexion, the spiral mode of
growth of itself brings about a continuity of the canal-system throughout, by means of the
marginal plexus ; the consecutive whorls not being added one to another like the successive
annuh of <75^c7oc/y^««, each of which is (so to speak) closed ov complete in itself; but being
formed by the prolongation of the spiral lamina and of the marginal cord, which may be
considered as always open to indefinite extension.

Fig. XLIV.

447. Reverting, now, to the generic differentiation between OpercuUna and Nummulina
that has been based by MM. D'Archiac and Haime on the closing-in of the spire, which
thev affirm to be a constant character of the latter, whilst in the former the spire seems ordi-
narily to open out so long as it continues to increase, — I have to remark that this is by no
means an invariable difference ; for I have met with several specimens of OpercuUna in which
the spire closes-in by a somewhat abrupt inflexion of the marginal cord, so as to produce a
rapid diminution in the size of the last four or five chambers, ending (as it would appear) in
a complete cessation of growtli. The closing septum of one of these specimens is shown in
fig. XLIV. Looking, however, to the circumstance that these specimens
bear but a very small proportion to those which exliibit no such tendency,
and also to the fact that some of the specimens in which this closing-in
is seen are very far from having attained their full growth, I am ilis-
posed to regard it as an abnormal, or at least as only an occasional
occurrence in OpercuUna ; and I must confess that, notwithstanding the
positive assertion of MM. D'Archiac and Haime, I still entertain doubts as
to whether it is to be accounted a uniform characteristic of NummuUHa
(^ 456). At any rate, the occasional occurrence of this condition in
OpercuUna deprives the character of that constancy which is requisite to
make it good for generic differentiation ; and if OpercuUna and Nummulina
are to be retained as separate genera, I cannot perceive by what features
they are to be distinguished, save by the marked compression in form,
the limited number of convolutions, and the external display of the
whole spire, which are the most obvious though not very important
characteristics of the former.

448. It only now remains to speak of certain appearances indicative
of reparation after injuries, which throw some light upon the physiology
of liiis type of organization. Specimens are not unfrequently met with,
exhibiting marked irregularities that may fairly be regarded as having
been produced by fracture. A portion of the outer part of the spire being
broken off, the wound heals by the formation of new shell at the margin ;
but in its further progress the spire often shows the effect of the injury,
in a narrowing of that part of the convolution which succeeds it, the
new chambers being formed (as it were) on the contracted basis to which their pre-
decessors have been reduced. A very remarkable feature in all these reparations is the

Front view of tlie
septal plane closing-in
the last chamber of
Opercnliiia.

GENUS OPERCULINA. 201

continuation of llic marginal cord along the fractured edge. It might have been supposed
tliat the wound would have been healed with some rude exudation, which would have
given rise to an amorphous shell-structure; but instead of this, we find the reparation
chiefly effected by a new production (probably by extension from the old) of that portion
which gives the most evidence in its canalicular striicture of being intimately connected
with the vital changes taking place in the organism. In one specimen in my possession,
a reversal seems to have taken place in the direction of growth after the fracture, the
spire having been broken across, almost through its centre, after the first two convolutions had
been formed; and the extension of the marginal cord which has closed-in the fractured por-
tion having proceeded not from the later but from the earlier of the two fractured extremi-
ties of the second convolution, its backward growth produces a reversal in the direction of
the spire. A somewhat similar retrograde increase has been alrcad)^ noticed among the
modes in which Orbitolifes is occasionally repaired \*\ 17.5) ; and it obviously shows that
every portion of the organism is equally capable of extending itself when left free to do so.
It is worthy of remark that the growth of this specimen subsequently to the injury has
taken place more after the plan of NuDuiuilinn than on the ordinary plan of Opercidina, the
convolutions being more numerous than usual and their rate of increase slow : there is
evidence, however, in the presence of a small fragment of the final whorl, that it underwent
the thinning-out which is characteristic of its type. — Notwithstanding the great number of
specimens which I have examined, I have not met with one that presented any such depar-
ture from the normal type of growth as woidd deserve to be termed a monstrosity ; so that
it would seem as if such aberrations were more frequent in the cyclical than in the helical
forms of Foraminifera.

449. Afjinities. — Since in this genus we have a complete development of all the cha-
racters that essentially distinguish the Nummuline type, it is obvious that it can bear no
direct relationship to any true Rotahne ; and although several approximations to the form of
Operculina are presented in the Rotaline series (^^ 353, 359, 367), yet as these are deficient
in all its other distinctive features, its relationship to them is one of analogy only, not of true
affinity. To Jinjjhistcgina it is obviously related much more closely, but it is difi^erentiated from
that type not only by its perfect symmetry and by the suppression of the alar and astral lobes,
but also by the development of the additional septal lamella, of the marginal cord, and of the
canal system. With Nummnlina the relationship of Operculina is so intimate, that, as we have
seen, it is difficult to find a valid generic distinction between them ; that suppression of the
alar lobes which constitutes the most obvious differentiation between the typical Operculina
and the typical Nummulince, being a character which (as we shall presently see, ^ 462) presents
itself in the " assiline" group of true Nummulites. Although there is no very intimate rela-
tionship between the typical Operculina and the typical Polystomella, yet the approximation
between some of the least developed examples of the former and the " nonionine'' forms of the
latter is so close that it is difficult to distinguish them ; and the essential distinction will
probably be found to lie in the distribution of the canal-system respectively characteristic of
these two types. To lleterostcgina the relationship of Operculina is extremely intimate ;
nothing more being required than the subdivision of its chambers into chamberlets, to con-
vert the latter into the former. Such a subdivision we have seen to occur in numerous other

262 FAMILY NUMMULINIDA.

instances (f^ 64, 119, 143), without any essential departure from the characters of the
respective types in which it occurs.

450. Geof/raphical a/ul Geolor/ical Disfributioti. — The statements already made regarding
the geographical diffusion of Amphistegina apply equally well to Operculina, except that the
dwarfed forms of the latter have a much wider geographical range, being found in European
seas, and even within the Arctic circle. It is only between or near the tropics, however, that
this type attains its characteristic development. — The earliest recognised appearance of Oper-
culina in geological time is in the Cretaceous series ; it seems to have become abundant at
the commencement of the Eocene period, numerous forms having been described from the
early Tertiaries of England, Continental Europe, and Asia ; and it is traceable throughout
the whole series of Tertiary formations, specimens of no inconsiderable dimensions being
found in the Crag of Sufiblk.

Genus III. — Nummulina (Plate XVIII).

451. History. — Among all the diversified types presented by Foraminifera, there is none
which has either so long or so generally attracted the attention of Naturalists as that which
is now familiarly known under the designation Ninmnilife. And this is easily accounted for,
on the one hand by the comparatively gigantic size which it usually attains, on the other by
the enormous aggregations of individuals which constitute, with some intermixture of other
t)^es of animal life, a stratum of limestone not unfrequently attaining a thickness of 1500
feet, which extends in an east and west direction through Southern Europe, Lybia and
Egypt, and Asia Minor, and is continued through the Himalayan range of Southern Asia into
various parts of the great Indian Peninsula, where it acquires a very extensive development.
It is of this Umestone that the Pyramids arc partly built ; and it is in relation to those struc-
tures that we find the first-recorded mention of Nummulitcs. Putting aside the question
whether they are the bodies referred to by Herodotus and Pliny, it seems indubitable that they
attracted the notice of Strabo, who adverted to the local traditions that they were the petri-
fied remains of the lentils employed by the workmen as food, and remarked that this was
improbable, since in his own locality (Amasia, of Pontus in Asia Minor) there existed a hill
prolonged into the middle of a plain, the stone of which is filled with similar lentil-like bodies,
— a statement which has been recently confirmed by M. de TchihatcheS", who has brought from
that locality a beautiful series of Nummulites. The first examples of this type noticed in
Europe seem to have been those of the neighbourhood of Paris, which were described by
Agricola and Conrad Gesner, the latter of whom regarded them as a kind of Cornu Ammonis.
Aldrovandus adverted to them as " freaks of nature ;" Kircher, who seems to have formed
his notion of them from the vertical sections often produced by fracture, compared them to
willow-leaves; while Clusius, who designates them "numismales lapides Transylvaniap,"
refers to the popular belief of the Transylvanians that they were pieces of money turned into
stone by King Ladislaus, in order to prevent his soldiers from stopping to collect them just
when they were putting the Tartars to flight !

GENUS NUMMULINA. 263

452. The commencement of a more exact knowledge of this type may be considered to
date from Scheuchzcr ; who, at the beginning of the last century, gave a description of the
examples of it occurring in Switzerland, which, as far as it goes, is very exact,*' regarding
them as a new type of Cornu Ammonis. Among succeeding naturalists, however, a great
variety of notions prevailed as to their essential character ; all which will be found elaborately
set forth in the admirable monograph of MM. D'Archiac and Haime (i). It will be suffi-
cient here to state that Lancisi (1719), who described them under the name of iiuinmi lapidci,
supposed them to be the madreporiform plates of marine Echinites ; whilst Buckmann, who
wrote specially on the lapis iminismaUs of Transylvania (1727), considered them to be bivalve
Mollusks ; and Bourguet in his Treatise on Petrifactions (1729), maintained that they were
the opercula of Ammonites. Notwithstanding that Guettard, in a special memoir devoted
to them (1770), pointed out that they have neither the large open mouth nor the siphon of
those chambered shells, they were ranked by Plancus (lxxxiii), Gualtieri (li), Soldani (c),
and most writers of the latter half of the eighteenth century (sometimes under the name of
Helicifes and Camerina, the latter given by Bruguicre), among Nautili or Ammonites. This
erroneous view was adopted even by Cuvier, who in his first systematic classification
('Tableau Elcmentaire,' 1798), ranged this type under the name of Camerinu after OrthorerK-
tites, at the end of his series of Cephalopod Mollusks ; and also by Lamarck, by whom the
genus NummuUtes was first created (lvii). The first good descriptions of specific forms were
those of Bruguiere ('Encyclopedic Muthodique,' 1792), who distinguished four species of his
genus Cdiiierinii, amongst them the C. lievif/ala ; and his descriptions of these were followed
by Lamarck.

453. The greatest confusion prevailed at the commencement of the nineteenth century,
in regard to the objects ranked together under the several designations applied to Nummulites ;
and this confusion is especially apparent in the memoir of Fortis (' Mem. pour servir a I'Hist.
Nat. de ITtalie,' 1 802), who introduced the new name Discolitlms for the bodies previously known
under the names of " pierres lenticulaires, numismales, frumentaires, helicites, et dernierement
caracrines \' and ranged under it the very different types which are now distinguished
as Nunimidbia, OrhUolite-'<, FaJjiilaria, Alveolhia, Orbiloides, and Ccdcarina. Towards clearing
up this confusion an important step was made by the separation effected by Lamarck (lvhi,
1804, 1806), between the Nummuline and the Orbitoline types; the genera Nummulites and
Lenticulltes (the latter founded on differences which have since proved not to be of generic
value) being retained among the chambered Cephalopods, whilst OrbitoUfes (under which
designation were ranked some of the forms now distinguished as Orbifoides) was referred to
the group of Zoophytes. As an illustration of the vagueness of the opinions yet prevalent on
the nature of these bodies, it is worthwhile to mention that Deluc (1802) and De Roissy
(1805) considered them to be altog-ether internal shells, analogous to the so-called "bone" of
the cuttle-fish ; whilst Dumcril in his ' Zoologie Analytique' (1806) likened them to the disks
of Forpitn, and ranged them among the Medusas. De Montfort (lxvii), according to his
wont, erected certain species of Nummulites into the new genera Lycopliris, llotalites, and
E(/eo)i ; names which are now entirely discarded. Subsequently (lx) Lamarck came to

* ' Specimen litliographiae Helveticse curiosse,' &c., Tiguri, 1702.

•iGJ FAMILY NUMMULINiDA.

perceive the strongly marked difFei-ences that exist between Niimmulites and the ordinary
siphoniferous Cephalopods ; and he regarded them as internal shells, completely enclosed (like
Spiri/Ia) within the animal, instead of giving lodgment to its body in its own chambers. In
this view he was followed by Deshayes and Defrance (xxix).

454. It was in 1825 that the Nummulites were detached by D'Orbigny (lxix) from the
siphoniferous chambered shells, and ranged with the minuter shells then first distinguished
by the term Foramiiiifera ; still, however, being considered to belong to the class of Cephalo-
poda. The Lamarckian designation Numnmlites was altered by D'Orbigny to Numnmliua, on
the ground that the genus had existing representatives; the genus LrnticnUte^: was not
adopted, having been previously shown to be untenable ; but a new genus JsnUiua was
created for the reception of those forms in which the investment of the earlier whorls bv the
later is incomplete, so that the turns of the spire are partially apparent, — a distinction which
we shall presently find to be of no essential importance. His description of the Nuramulitic
type was extremely inexact ; and the first approach to a more precise account of it was given
by Sowerby in his 'Mineral Conchology' (1829), who accurately described and figured the
true aperture of communication between the chambers (which does not seem to have been at
that time recognised by M. D'Orbigny), and traced the alar prolongations of the septa from
the peripheral margin towards the centre on either side. Numerous dissimilar forms of
Nummulites were subsequently brought to light by the researches of geologists in various
localities ; but for some time no essential advance was made in the knowledge of their struc-
ture ; and the discovery of M. Dujardin in regard to the Rhizopod character of the animal of
Foraminifera generally does not seem to have been applied to this particular type, until
MM. Joly and Leymerie applied themselves to the investigation of its conformation. Their
Memoir (liii), published in 1848, brought together most of the results attained by previous
inquiries, which were confirmed by their own researches ; but they did not discover any
new points of importance, — the chief novelty which they announced having been previously
put forth by M. de Keyserhng,* though probably without their knowledge. According to
these observers, the spiral lamina of Nummulites is perforated with large apertures, the con-
tinuity of which through successive layers forms canals reaching from the median plane to the
surface on either side ; these canals are filled up in the process of fossilization by calcareous
infiltration ; and the projection of the ends of the columns thus formed, from the surface
of specimens that have l^een subjected to attrition, gives rise to the granulations often
observable thereon. The inquiries into the minute structure of Nummulites on which I was
myself at that time engaged led me to the same view, without any knowledge that it had been
previously arrived at ; and having found myself fortified by the concurrence of MM. Joly and
Leymerie (with whose researches I became acquainted before the pubhcation of my own"), I
expressed it without hesitation (xii, p. 26) in the Memoir which contained the results of m)*
carliest researches into the microscopic structure of Foraminifera. It was from the first
opposed, however, by Prof. Williamson and Mr. T. Rupert Jones, wdio maintained that the
supposed passages filled up by infiltration w-ere really solid non-tubular portions of the original

* ' licmarques sur quelques points dc la structure dcs Nummulites,' in '•' Vcrliandl. dcr I'ussi^icli
Kaiser, miner. Gesellscb. zu St. Petersburg," 184'7, p. 17.

GENUS NUMMULINA. 265

shell, resembling those wliich occur in many recent types of Foraminifera ; and a more extended
acquaintance with the latter, and particularly the study of ( 'i/doch/peiis (xiv), satisfied me of the
correctness of their interpretation of the appearances by wliicli M. de Keyserling, MM. Jolj"
and Leynierie, and I myself had been originally misled. The error has l)cen endorsed, however,
by the high authority of MM. D'Arehiac and Haime (i) ; and, though I shall have to revert to
this subject more fully hereafter (^ 463), I may here remark that the contrast between the
transparent semi-crystalline aspect of the non-tubular portions of the shell, and the brown
semi-opacity of the tubular portions, is so striking in many Nummulites, whilst the limits
between the two are often so sharply defined, that the misinterpretation of these appearances
by such as have not familiarised themselves with analogous appearances among recent Fora-
minifera is almost inevitable.

455. In my own Memoir, which was for the most part restricted to an account of the
structure of a single species, iV. lavif/ata, attention was for the first time drawn to the double-
ness of tlie septa that divide the chambers, and to the existence of a set of interspaces
between their laminoe, communicating with passages excavated in the walls of the chambers ;
to the minute tubularity of the shell forming the spiral lamina, and to the coarser tubularity
of that which forms the marginal cord ; as well as to the various structural features which
indicate the conformity of Nummulites to the general type of Nautiloid Foraminifera, as
elucidated by Prof. Williamson's observations on Polystonella crispa : and I further drew
attention to the varieties in the mode in which the alar prolongations of the septa are
disposed on the surface of the previous convolutions, as likely to afford characters of value
in the differentiation of species. — Not long afterwards (xviii) Mr. Carter published the results
of his inquiries into the structure of the allied sub-genus Operculina, which led him both to
confirm and to extend my discovery of the canal-system in Nummulite; and having examined
specimens of Nummulite with the additional light thus obtained, he saw enough to satisfy
him of the essential similarity of the distribution of the canal-system in the two types. The
elaborate monograph (i) of MM. D'Arehiac and Haime, which appeared a few years later,
brought together every discoverable notice of this type from the earliest times, giving a con-
nected history of the progress of knowledge respecting it, of which I have freely availed
myself in the preceding outline. They embodied also the most important parts of the
descriptions of its structure which had been given by those who had investigated it ; and to
these they added some new facts of importance, by following out the modifications which the
fundamental type undergoes, especially in regard to the course of the alar prolongations of
the septa, — an inquiry which I was myself only prevented from pursuing by the want of the
requisite materials. We shall hereafter see (^ 462) that these modifications (to the importance
of which as differential characters I had specially directed attention) furnish the basis of their
division of the genius into subordinate groups. All the reputed species and their synonyms were
most carefully investigated by them ; and they succeeded in reducing a chaotic assemblage of
about a hundred and fifty* to an orderly arrangement of fifty-five. According to the ideas of
classification then prevalent, they were fully justified in the differentiation of the greater part of

* According to the Authors ubove referred to, (wenlij-two of the best kuowii species of Num-
mulite figured in catalogues as mnety-eight ; of these, 5 had been placed in tvjo genera, 1 in

34

266 FAMILY NUMMULINIDA.

these, if not of all ; but the knowledge since acquired of the range of variation among Fora-
minifera generally, and in the allied genus OpercuUna in particular, justifies a doubt whether
the diiferences between them are really more than varietal, and whether, if a sufficient number
of individuals -were compared, they would not be found as gradational as are those wc have met
with elsewhere (see ^^ 434 — 438). The latest contribution to our knowledge of the structure
of Nummulites is contained in a recent paper by Mr. Carter (xxiii a), which contains the
results of his further study of the subject, especially in regard to the distribution of the canal-
system. I feel it due to myself to state that the account of that system which I shall pre-
sently give is entirely based on my own previous re-investigation of it, with the light which
I have derived from my examination of Opercullna ; and that the illustrations in Plate XVIII
had all been not only drawn but printed before the appearance of Mr. Carter's paper,
in which as to most points it will be found that I fully concur. In regard to the question of
specific distinctions in this genus, I have been led by my own independent observations to an
entire concurrence with the views recently put forth by Messrs. Parker and Rupert Jones
(lxxx h), whose very careful and thorough investigation of the subject entitles their views to
the respectful consideration of such as have formed their notions of the differentiation of
species on the ordinary descriptions based on the examination of small numbers of specimens.

456. External Characters. — What may be considered the typical or characteristic form
of the Nummulite, is a double-convex lens of moderate thickness ; but the convexity gives
place in certain cases to a flattening which approaches that of the flattest varieties of Oj^er-
ctdina, whilst in other instances it is so greath' augmented that the lenticular form is con-
verted into the spheroidal. A wide range of variation exists in this respect among indi-
viduals of what must be accounted (according to the views of the best systematists) one and
the same species. Thus, in a Nummulite very common in Scinde (which was formerly con-
sidered by INIr. Carter to be the N. obtusa of Sowerby, but which he now regards as the N.
perforata of D'Orbigny), the thickness of the lenticular specimens is a little less than half the
diameter, the former being 4| lines while the latter is IOt ; but the proportion of the
thickness to the diameter may increase until it reaches nearly three-fourths, the former
being 9 lines whilst the latter is 1 2\, so that the body becomes globose ; whilst, on the
other hand, the thickness may diminish until it is scarcely more than one-third of the
diameter, the former being 2\ lines and the latter 7. And what is even more remarkable, in
a recent form which I have described (xv) under the name Amphister/ina Cuniingii, but which
I am now satisfied, for reasons already given (^ 420, note), to regard as a true Nummidina,
although the form of the shell up to neai-ly its full growth is that of a rather thick bi-convex
lens, yet the last whorl spreads out in a manner which alters its contour to even a more
remarkable degree than we ever see in OpercuUna. The two lateral surfaces have usually a
nearly equal curvature ; and any want of s)'mmetry is usually due rather to a departure of
the median spiral from the plane on which it normally revolves, than to any excess in the
growth of one side beyond that of the other — though such an excess unquestionably does
occasionally present itself. The diameter of Nummulites usually ranges between 1-I6th inch

three, 2 in four, 3 in five, 1 in siie, 1 in seven, and 1 in eigtit different genera ; and of specific names,
4 species had received tliree, 1 four, 3 five, 2 six, 1 seven, 1 nine, 2 ten, and 1 eleven.

GENUS NUMMULINA. 267

and 4^ inches ; a considerable proportion of the reputed species ranging between half an inch
and'an inch. This type is consequently the most gigantic in its dimensions of all Foraminifera ;
its largest forms being only approached by Tliioporiis, Cychclypcm, and Alvcolina, whilst its ordi-
nary size is equalled by that of none save PatdUna, Orbitoides, and OrhiloUte^. The fossilized
specimens which afford us the most abundant means of studying this type, very seldom present
what was probably their original surface quite unaltered, having nearly all been subjected
to more or less of abrasion or decomposition ; but in those which seem to have been least
affected by such agencies, the surface may be either entirely smooth, without any indication
whatever of the spiral convolution concealed within, or it may exhibit various inequalities
which are related to the peculiarities of internal structure to be presently described. In the
typical Nummulites, the last turn of the spire not only completely embraces but entirely
conceals all those which preceded it ; but in the group which has been formed by some into
the separate genus Jssilina, ranked by others as a sub-genus of Nummulites, and merely
distinguished by MM. D'Archiac and Haime as the exj}Ianate form, the earlier whorls remain
more or less visible, in consequence of cither not being invested at all by the later, or being
so invested that (as in Operadind) their spiral and septal partitions are not concealed. This
feature, however, is by no means peculiar to the explanate group ; since it presents itself
occasionally in specimens which are referred by other characters to a different position ; and
this kind of variation will not be surprising to such as have learned to appreciate at their true
value the corresponding variations of Operculina (% 441). In the type of this genus which
has come down to the present epoch, the N. plannlda, of which the N. radiata of Fichtel
and Moll is a varietal form, we find the centre of each lateral surface occupied by a " boss" of
transparent shell-substance, exactly resembling that which has been described as occurring
in Ampldstegina (% 421), and formed like it, by the filling-up with exogenous deposit of the
umbilical hollow left by the stopping-short of the alar prolongations, which, in the later
whorls, do not by any means extend to the centre.

457. The lateral surfaces, again, are often marked by punctations, which are sometimes
depressed, but are more commonly elevated into rounded tubercles. The presence of these
in unusual abundance and jjrominence has been held by MM. D'Archiac and Haime to cha-
racterise their group ol punctidata ; but as I am nov^- fully satisfied that these punctations
(whether elevations or depressions) only mark, as in Operculina, the spots in which the
ordinary canaliculated shell-substance is replaced by the solid or non-tubular, and that they
are not (as supposed by those and other observers) the indications of canals filled-up during
fossilization, I cannot attach any essential importance to their larger or smaller size, or to their
greater or less abundance, feeling confident that this character must be subject to the same
kind of variation in Nuramulito that we have seen it to present in OjjnrcuHna^- When the
surface has been worn by abrasion, moreovei', the non-tubular portions of the sliell, being

* On tliis point, I find myself supported by tlie careful observations of Mr. Carter, who re-
marks (xxiii a, p. 371) : — "The presence of the puncta, again, or their absence, their attachment to the
septal lines, or their separation from them, or the existence of both in the same specimen, or, indeed,
the absence of septal lines altogether, and the presence of an abundance of pinicta, may exist, re-
spectively, in the dift'erent forms of the globose Nummulite, N. inrforalu, which abounds in the valley

26S FAMILY NUMMl-LTNIDA.

harder tliau the rest, stand out in greater relief; and thus it happens that the septal hands and
tubercles, which maybe scarcely distinguishable on some specimens, become very conspicuous
on others, although the structure of the shell may be precisely the same in the two cases.
Not only are the septal bands of the regular spire thus brought into view where this remains
unconcealed by subsequent overgrowth, but those alar continuations of them may be rendered
visible superficially, which, in the typical Nummulites, extend themselves from tlie last turn
of the spire over the whole of each lateral surface ; and thus those surfaces may come to be
marked by striae, which sometimes directly converge from the margin towards the centre,
sometimes follow a course more or less sinuous, sometimes remain distinct from each
other through their whole length, and sometimes divaricate and inosculate more or less
freely so as to form an irregular reticulation. — From what has been stated of the diversities
of form among Nummulites, it will be readily apprehended that their margin will some-
times be rounded or obtuse, sometimes thinned away to an acute edge. In adult specimens
it seems to be always smooth, not being marked by those furrows wjiich wc shall find (as in
Opereidina) to traverse the surface of the " marginal cord" of the inner whorls ; and it is
affirmed by MM. D'Archiac and Haime that this type is distinguished by the entire closure
of the last chamber, since, even in the best preserved specimens, they have not been able to
distinguish that fissure between the inner margin of the septum and the outer edge of the
preceding whorl whicli elsewhere constitutes the passage of communication between adjacent
chambers. To this point I shall presently more particularly advert (^ 466).

458. Internal &fn/efurr. — For the satisfactory investigation of the internal structure of
Nummulites, it is requisite to make thin sections in various directions, capable of being viewed
under the microscope by transmitted light, and also to break the shell in various modes, so
as to obtain fragments which may be examined by reflected light.* Valuable information is
also furnished, especially in regard to the distribution of the canal-system, by the siliceous
casts of their internal cavities which have been occasionally preserved to us whilst the shells
underwent disintegration. — The indications afforded by these methods are such as to leave
no doubt that Nummulina very closely accords with OjiercuUna in the most essential features
of its internal structure ; and it will therefore be unnecessary to do much more than indi-
cate the differential characters by which the former type is specially distinguished.

459. When wc examine the spire of a Nummulite as laid open by a section through the

of Kelat and Scinde ; sliowing that much dependence must not be placed on the puucta or septal lines
for specific distinetiou." (See also Parker and Rupert Jones, lxxviii and lxxx i).

* Nummulites are generally most disposed to split through the median plane, so as to lay open
the cavity of the spire. This property, which has been noticed in all ages, is due partly to the larger
jiroportiou of cavitary spaces which occup}' that plane (as seen in Plate XVIII, fig. 9), and partly to
the inferior density of that portion of tlie shell— the marginal cord — which hounds the edge of the
spire. If a Nummulite be lieated in a flame, or over the fire, it will often split into two halves
through the median plane, if it be thrown into cold water or be struck lightly on its edge with a
hammer : and this it will he more disposed to do, in proportion as it has been but little changed by
fossihzation, and has its cavities free from mineral infiltration.

GENUS NUiMJlULIXA. 2Gy

median plane (Plate XVIIl, fig. 5), wc sec that the mimbcr of wliorls is usually much greater
than in Opcrcdinn, and that their increase in breadth is by no means so rapid, especially between
later convolutions. The progressive increase is tolerably regular in the earlier whorls ; but
it afterwards not unfrcqucntly happens that the spire enlarges rather suddenly, whilst some-
times it contracts again to a breadth inferior to that of the convolution it embraces. The division
into chambers, also, is far from being regular, the distance of the septa from each other being
subject to great variation even in the same whorl ; and chambers much smaller than the rest, and
apparently ahortkc (resembling tliose shown in Fig. XXXIX, ]). 253), being not unfrequently
seen. It is worthy of remark that \\hen the septa thus fail to divide the whole breadth of the
convolution, it is invariably on its outer side (so far as my observation extends) that they are
defective ; thus indicating that their development does not commence from the marginal cord
(as supposed by Mr. Carter, xxiii«), but from the internal edge of the spire, — as might
naturally be inferred from the position of the aperture through which the mass of sarcode
projects itself, whereon the new chamber is moulded. It is occasionally observed that a con-
volution subdivides into two, sometimes of equal, sometimes of unequal breadth ; this abnor-
mality is chiefly observable in such large and somewhat contorted forms as N. (/yzehensit and
N. disfaiis. When the subdivision is equal, each portion soon acquires the dimensions of the
original convolution, and continues to maintain a distinct course, sometimes undergoing
further subdivisions. But it often happens that the supplemental convolution is so much
smaller as to be a mere appendage to the principal, into which it returns after having retained
its distinctness through a course of greater or less extent. I am not acquainted with any
other helicoid type of Foraminifera in which such subdivisions occur ; and I am disposed to
connect it with the peculiar distribution of the canal-system to which I shall presently direct
attention (5[ 464) as tending to favour growth in a radial direction corresponding to that of
Cijdoclnpeus, in which type a multiplication of incomplete annuli is so common as to be
the rule rather than the exception. In specimens whose chambers are occupied by trans-
parent calcareous infiltration, it not unfrequently happens that the central portion of each
crystalline aggregation (as shown in the upper part of fig. 5) is deeply tinged with dark brown
matter, which has every appearance of being the carbonaceous residue of the original sarcode-
body.

4G0. The form and position of the apertural fissure which establishes the communication
between successive chambers, are precisely the same as in Operculina (If 440) ; and in this
type also we meet with " secondary pores"* scattered irregularly over the surface of the
septum, as shown in figs. 7, 8, 10. Each septum, in all well-preserved specimens, can be
distinctly seen to be composed of two lamcllce, between which the canal-system is interposed,
as shown in fig. 4 ; and it generally happens that the lamella which forms the anterior face of
one septum can be traced along the inner edge of the "marginal cord" (as shown in fig. 4),

* These " secondary pores" were first observed by nie in N. hevigata (xii, p. 34f) : I then be-
lieved, however, that they do not pass through both layers of the septa, but only establish a com-
munication between the chambers and the iutcrseptal passages — a notion which was supported by
Mr. Carter (xviii), but of the fallacy of which I afterwards became convinced by my own study of
the alUed recent types Opercidiim and Cycloclijpeus.

270 FAMILY NUMMULINIDA.

a considerable interval being sometimes left between them, so as to become continuous with
that which forms the posterior face of the next septum, as is well shown in many of
MM. D'Ai'chiac and Ilaime's beautiful figures. Hence it appears that each segment had its
own proper and complete investment, and that the marginal cord is really to be considered as
representing the " intermediate" or "supplemental" skeleton of Calcarina (•[[382). Where, on
the other hand, the septal lamellae abut against the " spiral lamina," they become absolutely
continuous with its innermost lamella, the structure of w^hich is precisely the same as that of
the numerous minutely-tubular lamellae, of w hich (as in Opcrc/ilina, ^ 442) its whole thickness
is made up.

461. This minutely- tubular structure is as distinctly seen in thin sections of Nummu--
lites whose texture has not been altered by fossilization, as it is in Opercidina ; but sometimes
the texture of tlie shell is so altered by fossilization that the tubular structure is replaced by
a minute prismatic arrangement. The explanation of this is, I believe, to be found in the
mode in which the shell is originally formed, which is doubtless the same as in Opercidina,
(^ 442). — The shell-substance over the septa (as shown at h, h, fig. 6) is not traversed by
tubuli, and is thus more transparent than the rest ; and it is of this dense hyaline substance
that the septal bands are composed, which are visible over the whole surface of the " assiline" or
" explanate" Nummulites. These bands are often broken up externally (as in Operculbia,
*{ 436) into rows of tubercles ; and such tubercles form the bases of columns of non-tubular
substance, which are traceable into the superjacent investments formed by the later convolu-
tions of the spiral lamina, so that they may even be continued through several of these to the
external surface, as shown at e, e, '-, fig. S. I have not met in the portion of the spiral lamina
that bounds the median portion of the chambers of an)'- Nummulite, with those intermediate
spots of non-tubular substance which are very common among OpcrmliiKe (^ 437) ; and
though such intermediate spots frequently occur in the portion of the spiral lamina which
invests the preceding convolutions, they are really formed on the basis of the septal tubercles
of the included whorls.- — ^The " marginal cord"which is shown in horizontal section at n, a,
figs. 1, 3, 4, 6, 9, and invertical section at a, a', figs. 3, 7, and of which the furrowed surface
is seen at a", fig. 7, bears a close general resemblance to that of OpercuHiia (^ 444) ; but
differs from it, as will be presently showii, in the disposition of the canal-system (^ 464).

462. When a typical Nummulite is divided by a section passing through its centre per-
pendicularly to the median plane, it presents an aspect (as shown in fig. 10) which remark-
ably difi"ers from that of a typical OjiermUna. For although the spiral lamina in the latter, as
well as in the former, is usually continued to the centre of the spire, yet in Opercidina it is
generally applied so closely to the lateral surfaces of the included whorls, that the cavities of
the chambers are but little or not at all extended inwards by alar prolongations ; and if, as
sometimes happens (Fig. XLII, a, e, p. 255), such prolongations should exist, they converge
uniformly towards the centre of the spire in which the alar prolongations of their septa all meet
(see Plate XVII, fig. 1). In NumnmVma, on the other hand, it is the rule (the exceptions being
chiefly found in the ' assiline' or ' explanate' group) for the investing portion of each convolution
of the spiral lamina to be separated from the lateral surfaces of the convolution it includes,
by the alar extensions of the chambers of its own marginal portion, which extensions are

GENUS NUMMULINA. 271

divided by prolongations of the marginal septa. These prolongations, in several of the
smaller Nummulites (for the most part belonging to the group of Flicata vel striata of
MM. D'Archiac and Hainie), converge radlalli/ towards the centre, sometimes with a slight
sinuosity. In a considerable proportion, however, of the middle-sized and larger Nummulites
(including the whole of the Laves and sublaves, and several of the Piuictulatce, of MM.
D'Archiac and Haime), the septal prolongations, though commencing radially at the
margin, as shown in Plate XVIII, fig. 1, />,' h' , soon become more or less sinuous, and meander
without any definite direction over the whole surface of the disk, occasionally bifurcating
near their origin, as shown at h" , b" . Another variety in the disposition of these alar prolonga-
tions of the septa consists in the formation of inosculations between those which adjoin one
another, so that the extensions of the chambers over the lateral surfaces are divided-up
into numerous isolated portions, as shown in fig. 9 ; and it is this arrangement which gives
rise to those numerous interruptions in the interspaces between the successive whorls, which
mark such vertical sections as the one represented in fig. 10. Further, these inosculations
may be so frequent as to convert the whole system of septal prolongations into a reticulation
covering the invested whorl, as shown at U , L', fig. 3 ; in which reticulation the continuity of
those prolongations is altogether lost. The Nummulites in which this plan prevails are
distinguished by MM. D'Archiac and Haime as Reiicidata and Sabreficulalce. Thus, as has
been pointed out by Messrs. Parker and Rupert Jones (lxxx /j), there are three typical plans
on which these alar prolongations are arranged, namely, the radiate, the sinuate, and the
reticulate ; but the first of these graduates imperceptibly into the second, and the second,
with the like absence of any definite boundary, into the third. Among the I'cputed species of
Nummulina, there are some {N. striata and N. Biaritxensis, for example) of which some indi-
viduals have radiate and others sinuo-radiate septal prolongations ; whilst there are several
(especially among the medium-sized '•' granulate" forms) which are radiate in their young
state and sinuate when older. The passage from the sinuate to the reticulate plan,
moreover, is marked by varieties of N. eomphmata, wherein inosculations of the septal
prolongations occur which assimilate their arrangement to that presented by varieties of
some of the sub-reticulate forms, as N. Immgata, which depart but little from the sinuate
type.

463. In all the larger forms of typical Nummulites we find columns of non-tubular
substance based upon the septal bands of tlie interior convolutions, and recdving additions
to their height from successive investments of the spiral lamina, the substance of which is
tubular where it overlies a surface whose tubularity allows the exit of pseudopodia, whilst it
is non-tubular when the subjacent surface is of the like description. In N. loevigata and
several other Nummulites, we see these columns (the form of which is very irregular) to be
included between the two lamellae of the alar prolongations of the septa, which diverge to
give them passage, as shown at e,' e , e', fig. 9. In other instances, however, these columns
pass up through the intermediate portions of the chambers, as is the case in N. Garansensis
(fig. 3), but still more remarkably in N. Vernettili (see i, plate vii, fig. 1 d) and N. Leymeriei
(i, plate xi, fig. 10 e). It is certainly the exception rather than the rule to be able to trace
these columns from the inner convolutions to the surface with the continuity shown in

272 FAMILY NUMMULINIDA.

Plate XVIII, fi?. 8 ; but such exceptions undoubtedly do occur,* although it is more common
to find the columns stopping short after they have been traced through several floors, or to
find that, without an absolute loss of continuity, their axes are shifted a little to one side or the
other — of both of which conditions examples are seen in fig. 9. Extensions of the non-tubular
substance from the septal bands of the spiral lamina over its intermediate substance are not
uncommon ; and it is stated by jMr. Carter (xxiii a, p. 321) that in T. jjerforata these
extensions inosculate so as to form a minute reticulation all over the cameral spaces.

464. The intcrseptal portion of the '" canal-system" of Nuiiij/ii/liita bears a very close
general resemblance to that of Opcrcidiiw. In every septum (Plate XVIII, fig. 7,,/) there seem
to be at least two principal branches (seen in horizontal section at/',/, fig. 4, and in vertical
section at f ,/', fig- 8) which originate from the marginal cord of the previous convolution, and
which converge as they pass outwards, and inosculate so as to form a network (fig. 7), some
branches from which enter the marginal cord of tiieir own convolution as shown in fig. 6.
The marginal cord, however, somewhat difl'ers in structure from that of Opcrculliia. Although
such a minute reticulation as that shown in the siliceous cast of i\". stria1a,\ represented in
Plate XXII, fig. 0, may undoubtedly exist, yet the evidence of sections all tends to show
that the marginal cord is usually penetrated by canals of a larger size, of which some run
across it either radially or obliquely, w^iilst others traverse it in a longitudinal direction, the
two sets occasionally inosculating, but not forming anything like a network. The radiating
canals are well seen in vertical sections which divide the cord transversely (Plate XVIII,
fig. 2, d , a) ; and their existence was pointed out by me in my former memoir, although I
was not then aware of their import. Such sections also show the orifices of the large longi-
tudinal canals which they divide transversely. The disposition of these canals is somewhat
irregular ; but generally there are found two passing in close proximity to each other along
the inner edge of the cord, of which one is often brought into view in sections traversing the

* I cannot but feel .surprised at the protest entered by MM. D'Arcbiac and Haime (p. 48),
against the accuracv of tlic figure in my former memoir on Nummulilcs of which fig. 8, Plate
XVIII, is a copv. Not only are tliose figures exact representations of a specimen in my possession,
draivn bv an artist (Mr. George West), whose accuracy in tlie delineation of subjects of this class
cannot (I ventiu-e to say) be surpassed, but they are precisely paralleled as to this particular by several
of the admirable figures in !MM. D'Arcbiac and Haime's own Monograph ; whicli show an equal
continuitv in the non-tubular columns (sec especially plate iii, fig. 7, e, and plate iv, fig. 9, d).
The theoretical objection drawn from the spiral plan of construction seems to me altogether without
weight, wheu it is borne in mind how entirely destitute of any definite direction are the alar pro-
longations of the septa in Nummulites of the sinuate and reticulate types. I am strongly inclined to
believe, from considerations based on the probable mode of formation of the tubular shells (^1f 59, 442),
that the disposition of the alar prolongations of the septa will be governed in no small degree by that
of the tubular and solid portions of the surface of the spiral lamina of the previous convolution, over
which they extend themselves.

t It is worthy of note that this species belongs to the radiate group, which is most nearly allied
to Operculina.

GENUS NUMMULINA. 273

median plane (figs. -4, 6) ; and two more nearer to its outer edge, at a wider interval from
each other. These last, which seem to be the representatives of the spiral canals in Opercu-
liiia, sometimes lie close to the surface of the marginal cord, from which their outer M'alls
form a projection, as shown in fig. 7; whilst in other instances they seem to be merely
furrows in its surface of unusual depth, not covered-in externally, as has been noticed by
MM. D'Archiac and Haimc in N. planulata (i, p. 63, pi. ix, fig. 7), and by Mr. Carter ia
N. Iiaimo)idi (xxni, a, p. 311, pi. xvii, fig. 15). All the longitudinal furrows with which
the surface of the marginal cord is always strongly marked, arc probably to be regarded (as
in Operculina, ^ 444) in the light of canals not completed into tubes by shell-substance ; the}'
seldom present that inosculation by transverse or oblique furrows which is often to be seen
in Operculina ; but the orifices of the radiating canals are v'cry plainly to be distinguished in
them in well-preserved specimens, especially when the surface of the marginal cord has been
cleaned by dilute acid. It is evident both from vertical and from horizontal sections (figs. 2
and 4), that the radial canals which cross the marginal cord, and which establish a direct
continuity between the interseptal system of each whorl and that of the succeeding whorl,
constitute the most important feature of the canal-system ; this communication being quite
independent of the spiral canals, with which the radial canals here only incidental!}^ inoscu-
late. Thus the canal-system of NummuUna comes to bear a stronger resemblance to that of
Cydocli/pcus than to that of OjJerculbia ; the manner in which the interseptal systems of
successive convolutions are brought into direct continuity with each other by the canals that
cross the marginal cord, being almost identical in the two former cases (compare Plate XVIII,
fig. 4, with Plate XIX, figs. 6, 7), whilst in the latter there is no such continuity, the
"marginal plexus" of the cord itself afi'ording all the means of communication that exists in
addition to the spiral canals. Hence it seems fair to surmise that whilst in Operculina the
growth is continuously spiral, the increase being effected by successive gemmations from the
stolon that issues from the apertural fissure, the extension of large pseudopodial prolongations
through the radial canals of the marginal cord may take a considerable shave in the process
in NummuUna, so that its growth may be partly radial, as in Cijchchjpeus ; especially since this
indication harmonises in a remarkable degree with that which we have seen to be furnished by
the occasional bifurcation of the spire (^ 459). — Besides the radial and spiral canals, we find
branches from the interseptal system proceeding towards the two lateral surfaces, usually either
in the substance of the non-tubular columns (as shown at e, e, fig. 7) or in close contiguity to
them. These branches, however, do not seem to attain the number and importance which they
possess in some other instances. Other branches, again, occasionally extend themselves from
the interseptal system over the intermediate portions of the spiral lamina, here again being-
surrounded by non-tubular substance ; this, however, seems rather an abnormal than an
ordinary distribution. — The interseptal system of canals is continued through the alar prolon-
gations of the septa • and where these inosculate into a network, tlicsc canals form a complete
reticulation surrounding the subdivisions of the chambers, as shown in fig. 3.

465. Varieties. — -It will doubtless seem strange to such Palaeontologi-sts as have made a
special study of Nummulites, and have not familiarised themselves with the wide range of
variation that characterises the group to which they belong, for mc to affirm that among all the
reputed qjecies of this type, I cannot satisfy myself that there are any which are entitled to a

35

274 FAMILY NUMMULINIDA.

higher rank than that of varieties. Taking the admirable monograph of MM. D'Archiac and
Haime as a guide, and testing the value of their specific differentiations by the knowledge
I have gained from the study of other types, and especially from that of OpercuUna, I find
that these are nearly all based upon characters which I have found to be so inconstant as to be
altogether fallacious. It is quite true that it would be a matter of no difficulty to pick out a
series of well-marked types presenting respectively the radiate, the sinuate, and the reticulate
arrangement of the septal prolongations, and characterised by great differences in figure and
proportion ; and under these types a large number of individuals might be unhesitatingly
arranged. But each series of individuals thus grouped together under one designation will
be sure to exhibit very considerable diversities ; and with every increase in the number com-
pared, especially when fresh specimens are brought from different localities,the range of these
diversities will be found to increase, and doubts will hence arise as to the place of particular
individuals, which mark the fallacy of any attempt to establish definite boundary lines between
the groups in question. Referring to my detailed comparison of different varieties of Opercu-
Una (xv) as affording the chief basis of my conclusions on this point, I might here limit
myself to the general statement that neither external form and proportions, the relative size of
the primordial chamber, the number and breadth of the convolutions, the number of chambers
in a convolution, the size and proportion of the chambers, the closeness with which the lateral
surfaces of the earlier convolutions are embraced by those which succeed them, the degree to
which the alar prolongations of the chambers extend themselves over the lateral surfaces,
nor the amount of non-tubular shell-substance which forms columns and plates within, and
shows itself on the surface in the granular tubercles or ridges with which it is occasionally
marked, — form any sufficient justification, either separately or collectively, for specific differen-
tiation. Nor, for the reasons already stated (^ 462), can I attach any higher value to
the course taken by the septal prolongations ; since, although they serve to mark three
primary types under which the numerous varieties may be distributed, they do not furnish
characters of sufficient definiteness and constancy for that absolute differentiation which is
required to satisfy the ordinary notion of a zoological species. — On this point I am happy to
find myself in full accordance with Messrs. Parker and Rupert Jones, by whom the relations
of the different forms of Nummulites have been studied far more systematically than they
have been by myself (lxxviii, lxxx h) ; their general conclusion being that " although it is
expedient to have binomial terms at hand wherewith to name the more important varieties of
NummuUnce, recent and fossil, yet for the purposes of philosophical zoology, NummuUua may
be recognised as a genus with but a single species, which, for our part, we should consider to
be typified by N. perforata." And it is obvious from Mr. Carter's recent investigations
(xxiii a) that he, too, has been led to feel the impossibility of clearly defining the species of
Nummulites;

466. Affinities. — It cannot be requisite again to point out in detail the very intimate
nature of the affinity which exists between Nummulina and Operculina ; indeed the difficulty
lies in drawing a definite line of demarcation between them. For whilst in undoubted
OpercuIiiicB we occasionally find in tlie earlier whorls that the alar prolongations of the
chambers extend themselves over the lateral surfaces of the included spire even to its centre,
we often find in undoubted Nummulina, especially those of the radiate group, that the alar

GENUS NUMMULINA. 275

prolongations of the chambers of the later whorls do not extend over the central portion of
the earlier, but leave its spire exposed. This is the case with some of the largest existing
Nummulrna;, — those of the Australian coast; between which and the OperciiJina of the same
seas, there is a continuous gradation. And the closing-in of the last whorl in the adult, which is
affirmed by MM. D'Archiac and Haime to be the characteristic distinction oi Nummulina, can no
longer be so regarded, when we find that not only does the same closure occasionally occur in
O'percnliiia (^ 447), but that, in an indubitable NirnniiiiJlna, the last whorl opens out as rapidly as
that of the most widely spreading Opercidina (^456). The large "boss" of solid shell-substance
which occupies the umbilical region on either side in many forms of the recent N. jjlanidata
(^ 456), filling up the space which would otherwise be left by the non-advance of the alar
lobes to the centre, exactly resembles that which we have seen in Atnpldsteghia. Although
the " reticulated " Nummiiliua differ widely from Orhiioides in their plan of growth, yet they
present a marked approximation to that type in one character which is of considerable importance,
namely, — the interposition of multiple flattened and isolated chamberlets between the successive
lamellse which intervene between the camerated median plane and the lateral surfaces. If Plate
XVIII, fig. 10, be compared with Plate XX, fig. 1, it will be seen how strong a resemblance
is thus imparted to the vertical sections of the two organisms ; and if the condition of the
segments of sarcode that occupy the reticulations into which the spaces between the .spiral
lamellae are divided in N. Garansensis (Plate XVIII, fig. 3), be compared with that of the
segments occupying the flattened polygonal chambers which are superposed one upon
another in Orhifoides MaidcUi (Plate XX, fig. 4), it will be seen that there is a strong simi-
larity in the two cases. In fact it is difficult to conceive how these reticular spaces can be
formed in Nnmmulina in any other way than the superficial flattened chambers of Orbitoides, —
namely, by the extension of the sarcode from the tubes of the surface immediately subjacent,
since their cavities are no less completely cut off from the chambers of the median plane in
the former case than they are in the latter.

467. Geographical Distribution. — Notwithstanding the extraordinary development of the
Nummulitic type within a comparatively recent geological period, it is now represented only by a
small number of forms, all of them referable to the type N. plamdata, occurring in arctic, tem-
perate, and tropical seas, and for the most part of very humble dimensions. The biconvex variety
found on our own coasts, N. variolaria, was first described as an existing NummuUte by Prof.
Williamson (ex, p. 37) ; its diameter usually ranges between 1- 12th and 1-1 6th of an inch. The
tropical variety, N. radiata (the Naidilns radiatm of Fichtel and Moll, who obtained it from the
Red Sea), attains on the Australian shores a diameter of l-5th of an inch ; while the diameter of
its Philippine specimens,* of which the younger examples seem exactly conformable to the
preceding, is increased in one direction by the spreading-out of their last whorl to more than
l-4th of an inch. This form belongs to the group with radiating septal lines, which pi-esents

* This remarkable recent form of Nummulina, fully described by me (xv) under the erroneous
designation Amphistegina Cumingii, whilst agreeing with the typical Nummulinee in every essential
particular, differs from them only in possessing a central boss of non-tubular substance like that of
Amphistegha, and in the opening-out of its last whorl like that of Operculina.

276 FAMILY NUMMULINIDA.

the closest approximation to Operculina ; and its relationship to that type is still more remark-
ably evidenced by the spreading-out of its last convolution.

468. Geological Distribution. — There is no fact in Palaeontology more striking than the
sudden and enormous development of the Nummiilitic type in the early part of the
Tertiary period, and its almost equally sudden diminution, bordering on complete extinction.
The precise position of the immense beds of " Numraulitic limestone," the vast geographical
extent of which has been already sketched (1 451), has been a subject of much discussion ;
but the researches of M. D'Archiac, Sir R. Murchison, Sir Charles Lyell, and others, leave
no further doubt that these beds belong to the early part of the Tertiary period, and that
they correspond in position with the " Calcaire Grossier" of the Paris basin, and with the
" Bracklesham" and " Bagshot" beds of the London and Hampshire basins, in which
deposits alone are Nummulites found in the British islands. Although Nummulites have
been described as existing at periods anterior to this, it seems probable that such descrip-
tions have been founded on the occurrence of other helicoid Foraminifera bearing an incom-
plete resemblance to them. What could have been the conditions which so specially
favoured their production at the period in question, — which forced them (so to speak) to the
attainment of a size so uncommon among Foraminifera, — which occasioned the development of
such a multitude of varietal differences (some of these being limited to particular localities,
whilst others present themselves in nearly all the regions in which Nummulites abound), — and
which promoted and sustained the multiplication of individuals through a sufficiently long
succession of ages to cause a vast thickness of solid rock to be formed of little else than
their remains,* and what change in those conditions put a sudden and almost complete stop
to these operations, constitute most interesting subjects for physiological and geological
inquiry. Comparatively insignificant forms referable to N. jiilaimlata are the only examples
of this type which can be traced into the later Tertiary strata ; and these have continued
to maintain themselves to the present time through changes which have proved fatal to tlicir
gigantic congeners.

Genus IV. — Polystomella (Plate XVI).

469- Histon/. — Of the minute shells to which the generic name Puli/stomella is at present
assigned, one species, now known as P. crispa, secm.s to have early attracted the attention of
conchological observers and collectors, on account both of its beauty and of the frequency of
its occurrence ; having been described and figured more than a century ago by Plancus and
Gualtieri, and adopted by Linnreus under the designation Nautili's into his ' Systema Naturae.'
By this designation it continued to be generally known from the time of Linna;us to that of
Lamarck ; having been described and figured by Walker, Soldani, Fichtcl and Moll, Montague,

* I have found, by the examination of numerous thin sections of Nummulitic limestones, that
the matrix wherein the entire Nummulites arc embedded is chiefly made up of more minute specimens
of the same types, and of comminuted fragments of the larger ones.

GENUS POLYSTOMELLA. 277

Dillwyn, and many other writers of the latter part of the last and the early part of tlie present
century. Bv Do Montfort, indeed, tlic examples of this type that had been described and
figured by Fichtel and ^loll were erected into no fewer than six new genera ; neither of these,
however, was adopted by any succeeding systematist, until Ehrenberg (xl) revived the name
Geoponus long after the present designation of the genus had been fixed. Its dissimi-
larity to Ncuililiis \\<x% first clearly pointed out in 1822 by Lamarck, (lx) who conferred
upon it the generic distinction Foli/Nfo.nclla ; and his definition of the genus was as follows: —
" Coquille disco'ide, multiloculairc, a tours contigus, non apparens au-dehors, et rayonnee a
I'exterieur par des sillons ou des cotes qui traverscnt la direction des tours. Ouverture com-
posce de plusieurs trous diversement disposes." By Blainville this type was described (vi)
under the name Vorficialk ; but Lamarck's designation was restored by M. D'Orbigny (lxix),
who, however, altogether misconceived the structure of the organism to which it was applied.
The aperture, which had been but vaguely indicated by Lamarck, was described by D'Orbigny
(lxx) as formed by " Ouvertures nombreuses, eparses, en bordure ou formant un triangle a la
pmiie siiperieure de la derniere loge, et se montrant encore ouverts dans les fossettes suturales
des dernieres loges;" he repeated (lxxui, p. 121) the assertion that " L'animal fait sortir
des filamens non seulement par des ouvertures du dessus de la dernicre loge, mais encore
par des pores des cotes des dernieres;" and in his latest publication on the subject
(lxxiv) he more concisely reaffirms the same error as follows: — "Coquille nautiloi'de,
pourvue de nombreuses ouvertures sur la derniere loge et sur les cotes de la coquille ;
une cavite simple au loges :" — notwithstanding that the true structure of Poli/stomeUa criqja
had in the mean time been elucidated by Prof. Williamson in his admirable memoir on
that species (cvii). — Subsequently to Prof. Williamson's memoir, an elaborate account
of the characters of the genus Poli/stonicJlu, and especially of a species designated P.
strii/ilata (which is only one of the multiform varieties of P. crispa), has been given by
Prof. Max Schultze (xcvii) ; who had the advantage of being able to study this organism in
tiie living state, and has thus been enabled to give a beautiful figure, not merely of the
shell, but also of the pseudopodia protruded from various parts of its surface, as well as to
make preparations of the sarcode-body of the animal by dissolving away the shell in dilute
acid. He does not seem, however, to have had the advantage of a full knowledge of Prof.
Williamson's memoir, his acquaintance with it being apparently limited to the abstract of it
contained in 'I'lnstitut' (No. 787); and he has not availed himself as fully as is desirable of
the mode of examining the intimate structure of these minute objects by the preparation of
very thin sections. In every point, in fact, in which he differs from Prof. Williamson, I am
satisfied that the truth lies with the latter ; and this not merely on account of the entire coin-
cidence between the results of my own inquiries into the structure of Polystomella crispa and
those of my accomplished predecessor, but also because our views are in every respect borne
out by the structure of the much larger and more highly developed form of PoJijalomdla which
I am presently to describe.

470. As this type presents itself under a variety of forms, which differ not only in
external features, but in internal structure, it will be desirable to give sepai'ate descriptions
of two of its most characteristic examples, known as P. criyja and P. cratimlata ; the former of
which is a common inhabitant of British and other temperate seas, whilst the latter, which is a

278 FAMILY NUMMULINIDA.

far more highly-developed organism, is met with in the seas of warmer latitudes, my largest
specimens of it being those collected by Mr. Jukes on the coast of Austraha.

471. PoLYSTOMELLA CRISPA. External Characters. — The shell of T. crispa is usually
lenticular in form, its edge being sometimes rounded, and sometimes carinated ; its diameter
is usually from l-16th to l-25th of an inch. Not unfrequently, especially in young specimens,
short spines project at intervals from its margin. Only the last whorl of the spire is anywhere
visible ; this, however, does not extend as far as the centre,* the umbilical region being
occupied by a solid deposit of shell-substance, in which minute punctations can be distin-
guished. The septal bands, which are convex anteriorly, are very conspicuous, dividing the
surface into well-marked segments. On the exterior of each of these segmental divisions,
strong transverse crenulations present themselves, which are deepest near the convex margin
of the preceding septal band, where they terminate somewhat abruptly, and usually disappear
before reaching the concave margin of the subsequently-formed chamber. The depressions
between the elevated ridges often present the appearance of orifices ; but this appearance is
fallacious, since at no period in the growth of the shell is there any passage through these
depressions to the cavity of the chamber; the only communication which the system of
spirally-disposed chambers possesses with the exterior, being afforded by a variable number
of minute orifices which are to be found near the inner margin of the sagittate septal plane
(Plate XVI, fig. 5, c), close to its junction with the preceding convolution. These orifices,
however, are often discernible with difficulty from the exterior. When the surface of tlie
shell is examined with a sufficient magnifying power, it is observed to be crowded with
minute tubercles ; and this tuberculated structure is often especially evident upon the septal
plane, and in the rows of depressions between the segmental divisions. These tubercles often
so strongly resemble apertures, that it is only when thin sections of the shell are examined
under a variety of aspects, that their real nature is determinable with certainty ; and some
excellent observers (amongst others Prof. Schultze, xcvii) have been deceived into the
belief that they are pores.

472. Internal Structure. — When the shell of P. crispa is laid open by a section passing
through the median plane, it is found to consist of a small number of convolutions, somewhat
rapidly increasing in breadth ; and each of these convolutions is shown by a vertical section
(fig. 5) almost entirely to enclose the preceding, the alar extensions of its segments being pro-
longed towards the centre, until they meet the solid umbilical nucleus. When the outer walls
of the chambers are examined from within (which is readily done by crushing a specimen, and
mounting the fragments in Canada balsam), a series of grooves are found to correspond with
the elevated ridges of the outer surface ; these grooves shallow towards the anterior or con-
cave margin of each segment, and deepen towards the posterior or convex margin ; and for a
short distance from the posterior septum each groove is converted into a tube by a narrow
lamella given off internally from the septum (Plate XVI, figs. 5, //, k'). These tubes, however,
establish no communication between the contiguous chambers ; for they are cnls cle sac, closed-in
by the lamella of the septum which formed the boundary of the previously-formed chamber.
In the living state they are occupied (as is shown by examination of the decalcified body,
Plate IV, fig. 28), by a set of processes h, b, of sarcode (see also Plate XVI, fig. 0, /?), which extend

GENUS POLYSTOMELLA. 279

backwards for a short distance from both the outer or lateral margins of each segment of the
sarcode-body, and then terminate abruptly. From the neighbourhood of the inner arch of each
segment, on the other hand, there proceeds a series of threads of sarcode (fig. 6, c) much
slenderer than tlie " retral processes " just described, which unite each segment to the two
contiguous segments before and behind, passing through the row of pores already mentioned
as visible along the inner margin of the septum. The substance forming the spiral lamina is
finely tubular ; but no such tubuh arc discernible in the septa, which exhibit only the > -shaped
rows of septal pores (fig. 5, r, c), whose number progressively increases with the dimensions
of the septal plane, and indications of interseptal canals, d, d, which seem to resemble those of
Operculina in their derivation from a pair of spiral canals whose transverse sections are seen
at e, c The solid umbilical deposit, /, V , is traversed through its whole thickness by straight
parallel canals proceeding directly towards the external surface, where their terminations
form the punctations already mentioned.

473. PoLYSTOMELLA CRATicuLATA : Evtcnuil CJiaracters. — The Australian examples
of P. craticulafa (Plate XVI, figs. 1, 2, a, b), are remarkable not only for their comparatively
large dimensions (the diameter of some of the specimens in my possession exceedino- one-
sixth of an inch), but for the considerable proportion of their two lateral surfaces occupied by
that solid calcareous nucleus which is confined in other forms to the umbilical region. The
diameter of this nucleus is usually about three-fifths of the whole diameter of the specimen ;
so that it covers and conceals all the earlier convolutions, meeting at its outer maro-in the
chambers of the last-formed whorl (as is made evident by vertical sections, fio-. 3 / / /' /')
which are consequently the only chambers that show themselves externally, although the last-
formed whorl does not itself extend far over the preceding. I have not unfrequently found
this umbilical nucleus, however, to be suflaciently transparent (after its surface has been cleaned
by a short immersion in dilute acid) to allow of the inner convolutions being discerned through
it, when the microscope is focussed down to their surface and a strong light directed upon
this; and it then becomes obvious that, if the solid nucleus were removed, the form of the
shell would be bi-concave instead of bi-convex (figs. 1, 3), the thickness of each whorl (/. e. the
distance between its two lateral surfaces) being greater than that of the preceding, and the
later whorls not extending themselves over those previously formed. The septa are marked
externally by bands which indicate their junction with the outer walls of the chambers : these
bands are meridional (so to speak) in their direction, extending from the margin of the
nucleus on one side to that of the nucleus on the other side ; they are not usually (in adult
specimens at least) either elevated above or depressed below the surface of the walls of the
chambers on either side of them ; but they are distinguished by their difference of texture,
their substance being much more transparent and glistening than that of which those walls
are composed. The surface of the central nucleus is marked at pretty regular intervals with
minute punctations (fig. 2, a), each of which occupies the centre of a little dimple or depres-
sion ; and rows of similar punctations are very commonly seen to extend from the nucleus on
either side, in a direction corresponding to that of the septal bands (fig. 2, b), two such
rows usually intervening between each septal band and that which precedes or follows it
(fig. 1, hh, h'Ji'). In the older portion of the last-formed whorl, it is sometimes to be observed
that these punctations with their surrounding dimples constitute the only interruption to the

280 FAMILY NUMMULINIDA.

general uniformity of the surface, the septal bands not being clearly distinguishable ; and this
disposition is commonly found to prevail on the surface of the inner whorls when it is exposed
by the removal of the outer [ii', it'}. In the newer portion of the last-formed whorl, on the other
hand, we may observe that instead of each punctation having a separate dimple of its own,
the corresponding punctations of the two rows lie in a succession of furrows that pass trans-
versely between the septa {gy ■, <j(i')- In the most recently formed portions of specimens that
have not attained their full growth, we find these furrows to be deeper towards the posterior
than towards the anterior margin of each interseptal space ; and in the deepest portion of
each of these furrows, which obviously correspond with tlic depressions of P. criqnt (although
much less pronounced), a minute punctation may be brought into view by careful examina-
tion, a corresponding row of punctations being also traceable on the other side of the septum.*
These varieties of superficial aspect may present themselves on different parts of one and the
same specimen ; and it will appear from the explanations which I shall presently have to
furnish, that they are occasioned by differences in the degree in which the proper external
wall of tlie chambers is thickened b)' an exogenous deposit upon its surface, continuous with
tliat of which the central nucleus is composed (f[ 476).

474. In stud3'ing the internal structure of P. craticidata , I have not been dependent only
upon the information afforded by sections of the sliell ; for I have had the opportunity,
through the kindness of Messrs. Parker -and Rupert Jones, of examining the beautiful siliceous
"casts" which they have obtained by treating with dilute acid specimens whose cavities had
been filled by an infiltration of silicate of iron. These casts (of one of which a somewhat diagram-
matized view is given in Plate XVI, fig. 9) represent, with the utmost fidelity, the forms and con-
nections of the various parts of the sarcode-body which occupied the cavities and channels of
the shell in the living state of this organism ; and for the reason already mentioned (p. 10) they
really afford us more information on those points than we could obtain from the decalcified body
the animal itself. In the general shape and proportions of its segments, P. cratlcuJata differs
remarkably from P. crispa as from most other nautiloid Foraminifera ; the breadth of each of
the later whorls being many times exceeded by the distance between its two lateral surfaces.
Thus the segments come to have somewhat of the form and arrangement which the carpels
of an orange would exhibit, if, instead of lying in a single circle round a central axis, tliey
w^ere disposed in a succession of whorls, with a progressive increase in their dimensions.
This comparison may be conveniently carried a little further. For as each carpel of the
orange has its own investing membrane, so that the partitions between the adjacent carpels
are double, so each segment of PoI^stomeJIa has its own proper shelly investment ; and further,
as the separate carpels of the orange are collectively invested by a general integument, which
also to a certain degree dips down between them, and which fills up what would otherwise
be void spaces about the two poles of the spheroid, so are the proper walls of the spirally

* In order to distinguish the orifices of these punctations, it is advantageous to remove from tlic
surface of the shell that opacity vrhich it derives from abrasion, and to get rid of the fine particles of
calcareous matter which often choke up and obscure its pores. This is readily effected by immersing
it for a short time in water so slightly acidulated with nitric or hvdrocliloric acid as only to e.xert a very
feeble degree of solvent power.

GENUS POLYSTOMELLA. 281

arranged segments of PoJi/sfomeUa strenglhencd and consolidated by a secondary calcareous
deposit upon their external surface, which constitutes a " supplemental skeleton" (^ 63).

475. The dimensions of the central chamber in which the spire of P. craliculata commences
are extremely variable ; the difference between the extremes of its size being, in fact, not less
remarkable than that which I have shown to present itself in Orhitolites (^ 177). Tims in
one specimen we may trace a progressive diminution in the size of the chambers as we
approach the central chamber, which is itself no larger than the chambers in nearest proximity
to it ; whilst in another not only is the size of the earlier wliorls and of their component
chambers considerably greater than usual, but the central cell alone occupies about tlic
same space as the first 2J whorls of the preceding. The average seems to be intermediate
between these two extremes. The lu'cadth of the successive whorls increases much more
gradually than in most other nautiloid Foraminifera, in this respect resembling Xiimmtdinn ,-
and there is no tendency whatever, even in the oldest and most developed specimens, to that
rapid opening-out of the spire, which is so marked a feature of the older specimens of Pciie-
roplis, OpercuJina, and Heterostet/ina. The largest number of whorls I have met witli in any
individual is eleven : the earlier four or five of these completely invest the preceding, tlieir
chambers extending on either side to the centre of the spire, as is partly shown in the
vertical section (Plate XVI, fig. 3) ; but as new whorls are added around these, the chambers
cease to be thus prolonged over the preceding whorls, which would consequently be
apparent externally if not concealed by the nucleus. The distance between the successive
septa remains nearly the same after the spire has made two or three turns ; and thus the
size of the segments as seen in an equatorial section remains pretty much the same through-
out all the later growth of the shell, while the number of chambers in the successive convo-
lutions increases nearly in proportion to the length of their gyration. The chambers of each
whorl seem normally to alternate in position with those of the adjacent whorls ; so that lines
drawn from the centre of the spire through the septa of one convolution would pass through
the middle of the chambers of the next, and would again meet the septa of tiie convolution
beyond. This arrangement, however, is by no means constant, being very liable to be
disturbed by that hderpohdloii of additional chambers which is required for the augmentation
of their number in successive whorls : it will presently be seen to be related to the peculiar
disposition of the canal-system (^f 479), which here acquires a remarkable development and
importance.

476. Although, however, there is but little progressive increase in the dimensions of the
successive chambers, and of the segments of the sarcode-body which occupy them, as seen in
sections taken through the equatorial plane, it is made obvious by sections made at right
angles to this (Plate XVI, fig. 3) that a rapid augmentation takes place in what may be
termed the meridional direction ; the distance between the two lateral surfaces of eacli whorl
being considerably greater than between those of the preceding, so that the chambered
portion of the shell progressively increases in thickness from the centre towards the circum-
ference. The conical hollow thus left on each side in the central portion of the shell, is
entirely filled up by the solid nucleus already adverted to : the calcareous deposit of which
the nucleus is composed, however, is by no means limited to it, but extends over the whole

36

282 FAMILY NUMMULINIDA.

outer surface of each whorl, except where (in well-preserved specimens) the portion last
formed is as yet unconsolidated by it. For a careful examination of sections taken in
different directions makes it clear that whilst the internal portion of the spiral lamina that
forms the outer wall of each chamber is continuous with the nearest lamella of the adjacent
septum on either side (as is shown in the portion of fig. 1 which traverses the median plane),
the substance of the external portion is no less continuous with that of the calcareous nucleus.
The whole thickness of the spiral lamina formed by the coalescence of these two lamellae is
generally traversed by minute tubuli, passing in a radial direction from one surface towards
the other; but these have by no means either the closeness or the regularity which distin-
guishes the tubular structure in Operculina and Cj/cloclt/pcus, and the shell-substance is in
many parts so destitute of tubuli as to be of almost glassy transparence. The farrowing of
the external surface (^ 473) is seen in vertical sections not to be produced by mere superficial
excavations, but to proceed from a plicated arrangement of the spiral lamina as shown in
fig. 1 ; and this is related to the prolongation of the posterior margin of each segment into a
series of " retral processes" (fig. 9, 1-, /•)> corresponding to those of P. cri.yia (^ 175). They are,
however, much less elongated in this type, simply giving a crenulated margin to that angle
of the segment, which contrasts remarkably with the smooth unbroken aspect of its anterior
border. The spiral lamina which forms the outer wail of the chamber, being modelled (so to
speak) upon the surface of these retral processes, presents internally a corresponding series of
grooves, which are deepest towards the posterior margin, and become rapidly shallower in
passing towards the anterior margin, of each chamber, as is shown at a, a}, a", fig. 8 ; these
grooves are not, however, as in P. cri-ypa, completed into tubes for part of their length by an
additional lamella of shell given off from the septum (1| 472) ; but they are sometimes shown,
in sections which happen to traverse them, to be extended into ca;cal prolongations by back-
ward inflexions of the septa at their junction with the spiral lamina. The communication
between the successive segments of the same whorl is established by a number of minute
processes or stolons of sarcode (fig. 7, c, fig. 9, c), which pass at regular intervals between
their internal margins through a series of pores that can be distinguished along the inner
border of each septum (fig. \, c, c, c) close to its junction with the preceding convolution. I
have not detected in any instance, either in sections of the shell or in the siliceous casts
which so exactly represent the sarcode-body, any other communications between the chambers
or their contained segments; and lam therefore satisfied that Prof. Max. Schultzc must
have been misled by appearances when he stated (xcvii, p. 65) that various other parts of
the septal plane are marked by similar pores, — more particularly as his figures of the
decalcified body do not show that any other threads or stolons of sarcode pass between its
segments, than those just described.

477. So far, then, the structure of this comparatively gigantic type of Polustomella accords
very closely with that of the more delicate species previously described. I have now, however,
to give an account of a remarkable feature in its organization, namely, its highly developed
canal-system ; which, though not entirely wanting in P. crisjxt, is so imperfectly presented there
that Prof. Williamson may well be excused for having overlooked it, especially when it is
borne in mind that at that period the existence of such a system in Foi-aminifera was alto-
gether unknown. The general arrangement of this canal-system may be most readily aj)pre-

GENUS POLYSTOMELLA. 283

hended from an examination of the delineations of the internal casts given in Plate XVI,
figs. 7, 9 ; for the infiltrating substance which has penetrated the chambers has also found
its way not only into the main trunks, but also into the minute ramifications of this system,
and has thus given just that representation of their distribution and relations, which is
afforded in regard to the blood-vessels of the higher animals by a well-injected and clearly
dissected anatomical preparation. We observe, in the first place, that in each of what may
be termed the two polar regions of the spheroidal body, there is a continuous spiral canal
(fig. 9, e, c, e), which overlies the extremities of the segments. These two spiral canals com-
municate with each other by a very regularly disposed series of canals {dcV, dd'), which pass in a
meridittnal direction between the adjacent e.Kternal margins of the segments. And each of
these meridional canals gives off, in its course from one polar region to the other, a uniform
succession of pairs of short passages (/,/) that diverge from each other widely, one series
inclining backwards over the uniform anterior margin of the segment next behind it, whilst
the other series passes forwards in the intervals between the " retral processes" of the
segment next in front of it. The passages which thus diverge from the meridional canals of
the outer whorl speedily debouch at its surface ; but if we examine into the termination of
those appertaining to the inner whorls (which is best seen in such fragments as the one
represented in fig. 7), we find that they become continuous with the stolons of the whorl
which surrounds them, as is shown at c, c , fig. 9. Further, it may be perceived that each
of the meridional canals receives branches from the canal-system of the segment internal to
it J this point, however, can be more clearly made out in sections of the shell.

478. The spiral canals are frequently brought into view for part of their course, by
sections passing through the shell in a direction parallel to the equatorial plane but at no
great distance from one of its lateral surfaces ; and if such a section passes through the plane
of the inner convolution of the spiral canal, it often shows that the spiral canal communicates
towards its centre, with an irregular set of lacmice, which are excavated in the deepest part
of the solid umbilical nucleus. If, again, the plane of such a section is nearer to the lateral
surface, the portion of it which passes through the solid calcareous nucleus is seen to be
perforated by numerous apertures disposed at pretty regular intervals, and corresponding to
the superficial punctations. The relation of these to the canal-system is clearly evidenced by
vertical sections, such as that represented in fig. 3 ; in which we see at e, e the orifices of the
spiral canals transversely or obliquely divided, whilst the solid calcareous nucleus (//, /'/') is
itself shown to be traversed by straight canals, which spring from the successive convolutions
of the spiral canal, and pass directly without branching or inosculation to the external
surface. That this remarkable portion of the canal-system does not fully show itself in the
"casts" represented in fig. 9, is easily understood, when it is remembered that the whole
substance traversed by the straight canals having been removed, their long and slender casts
would be left entirely without support ; and the points at which these have been broken oft"
from the cast of the spiral canal are in fact to be seen on a careful examination.

479. It is shown by the comparison of vertical and horizontal sections of the shell with
fragments obtained by fracture (fig. 8), that tlie meridional canals {d d', d cl) are in reality
spaces left by the divergence of the two layers of which each septum is composed, in the

284 FAMILY NU.AIMULINIDA.

immediate neighbourhood of its junction with the spiral lamina constituting the external wall
of the chamber; and that they are thus homologous with the arches of the interseptal
system of canals that connect together the spiral canals of OpercnJina (■[ 445) — presenting,
however, a much greater uniformity and constancy in their disposition. The diverging
branches given off from these pass at once into the spiral lamina, beneath the ridges of the
shell which intervene between the furrows for the lodgment of the retral processes, as seen in
fig. 8 ; and through the thickness of the spiral lamina they run obliquely towards the external
surface of the convolution, usually increasing in diameter as they proceed. The divergence of
the branches of each meridional canal causes those proceeding from adjacent canals to
approach one another; and when the spiral lamina has attained its full development they
not unfrecjuently open at its surface into the same depression, this being midway between the
septa from which they respectively sprang ; and it appears to be from the correspondence of
these junctions with the intervals between the segments of the succeeding whorls, that the
alternating arrangement of the chambers of consecutive whorls arises, of which mention has
already been made (^ 475), the prolongations of sarcode which occupy the diverging branches
there passing into the stolons which connect the adjacent segments. It will be easily under-
stood, however, that the position of the external orifices of these diverging branches will
depend upon the thickness of the spiral lamina which they have to traverse before gaining its
surface. In the newest portion of a shell which has not yet attained its full growth, we find
that lamina comparatively thin ; its surface is distinctly marked by the septal bands (fig. 1,
<ig' (/(J) ; and the external walls of the chambers present an alternation of ridges and furrows
passing directly across from one septal band to another — the ridges corresponding to the
grooves of the internal surface that receive the " retral processes " (^ 476), and the furrows
with the internal ridges that separate these grooves. Into these furrows, wdiich represent the
deeper " fosscttes " of P. cri^jja, the diverging pairs of branches from each meridional canal open
by minute pores on either side of the septal band, as is shown aty/, yy', fig. 1. The subse-
quent formation of a calcai'eous deposit, continuous with that which solidifies the umbilical
portion of the shell, upon the external surface of the spiral lamina, renders the septal bands less
distinct, and obliterates the ridges and furrows of the intervening surface, as is shown in the
portion h //of fig. 1 ; and at the same time it carries the orifices of the diverging bi-anches from
the neighbourhood of the septa into closer proximity with those of the branches proceeding
from the adjacent meridional canals. As the diverging branches enlarge greatly in diameter
with their augmentation in length, their superficial orifices become more and more conspicuous ;
each is surrounded by a little pit or depression of its own (fig. 1, ii' , ii'); and the rows of
these depressions, when the spiral lamina has acquired its full thickness, constitute the only
markings wdiich it presents, the septal bands being completely obliterated, — as is best seen
on the surface of one of the interior whorls exposed by the removal of that which covered it.
The removal of the superficial portion of the spiral lamina, however, even when it is thickest
(which may easily be accomplished by the assistance of dilute acid), brings back these orifices
of the diverging canals to the immediate neighbourhood of the septal bands, which then
again become apparent. It is obvious, therefore, that these depressions in the thickened
portion of the shell of P. craticulata, being related only to the distribution of the canal system,
are essentially different in character and position from the superficial depressions of P. cr'ispa,
which intervene between the ridges that cover-in the retral processes.

GENUS POLYSTOMELLA. 2S5

480. The meridional canals are further connected with the older and more internal por-
tions of the organism, as well as with the newer and more superticial ; this connexion being
established by a series of branches that pass between the two layers of septa in a radial
direction (as is shown on the septum If, fig. 1), from the meridional canals of each convolution
to the stolons which unite the segments of that convolution. These, which may be distinguished
as the converging branches, are, liowever, much less regular in their distribution than
those which pass outwards from the meridional canals to the stolons of the succeeding
whorl.

481. Thus, then, it becomes apparent that by the two spiral canals, the number of con-
volutions of which equals that of the whorls of the shell, — by the very numerous meridional
canah, of which there is one for every segment of each whorl, — by the vast multiplication of
pairs of diverging brandies, of which each meridional canal sends off a number equal to that of
the connecting stolons between the segments, — and by the very considerable aggregation of con-
verging branches, which probably do not fall far short of the preceding, except in being single
while the}' are in pairs, — a very complete system of intercommunications is maintained between
the external surface and even the innermost portions of the shell. That these passages are
occupied in the living animal by prolongations of the sarcode-body, there can scarcely, I
think, be any reasonable doubt; and when we look to the remarkable development of what has
been elsewhere termed the " intermediate skeleton," but which may here be more appropriately
termed the " supplemental skeleton,"— namely, the secondary calcareous deposit which not
only forms the solid nucleus, but spreads itself over the entire surface, adding considerably
to the thickness of the spiral lamina, — it cannot be deemed improbable that the special pur-
pose of the canal-system is the formation and nutrition of this supplemental skeleton, which
has obviously no direct relation to the segments of the animal body contained within the
chambers. Through the trumpet-shaped diverging branches which open in such numbers
upon the surface of those chambers, and the straight canals which arise from the nucleus,
there will be abundant opportunity for the sarcode-body to extend itself over the whole
exterior of the shell, and thus to form any additional deposit upon its surface.

482. The two forms of Polgstomella now^ described differ from each other simply in
those particulars wliich mark degree of development, and which the experience of similar
diversities elsewhere forbids us to account as of specific value, the general plan of structure
being essentially the same in both. The excess of size and turgidity which distinguish
P. craticiilata, as compared with P. crispa, are not more remarkable than the like excess by
which the large Dendritina of tropical seas is distinguished from the starved-out Peneroplis of
the Mediterranean ; and the extraordinary development of the supplemental skeleton with its
i-elated canal-system in P. craticduta loses its value as a differential character, when the series
of intermediate forms is traced out, in which the superadded parts are gradually reduced to the
rudimentary condition in which they present themselves in P. crispxt. In these forms (which
have been accounted distinct species by D'Orbigny and other systematists) we meet with
various kinds of surface-marking, which are related (like the diversities already described, H 473,
in P. craticiilata itself) to the varying amounts of calcareous deposit which have been added
to the exterior of the spiral lamina. Other species, again, have been founded on the extension

286 FAMILY NUMMULINIDA.

of this exogenous deposit into solid prolongations radiating from the margin of the spire.
I quite agree with Prof. Williamson (ex) in regarding all these as varieties of P. crisjxi, since
the specimens collected on our own shores exhibit all the modifications by which they are
severally distinguished, though in a less obvious degree. Certain of these varieties have a
tendency to become partially unsymmetrical, one side being quite flattened and exhibiting the
whole of the spire, but the septal plane and aperture being but little affected. This is espe-
cially the case' with the P. macella {Nautilus maceUiis of Fichtel and Moll). It is one of these
unsymmetrical forms which has been described by D'Orbigny (lxxiii) from the Chalk of
Maestricht under the name of Faiijasina carinata. For additional remarks on the reputed
species of PoJystomdIa, I may refer to the judicious criticisms of Messrs. Parker and Rupert
Jones (lxxviii).

483. There is a group of forms, however, in which we meet with a greater departure
from the ordinary type of the genus ; the crenulations of the shell and the retral processes
of the sarcode-body lodged in them being altogether wanting, whilst the perforations in the
septal plane, instead of forming a series of isolated pores, run together into a continuous slit
or fissure along the margin of the included whorl, like that of Ojieradina and XuimnnUna.
The transition to this sub-generic type, which has been distinguished by the generic designa-
tion NoNiONiNA, is effected by the interesting form which was originally described by Fichtel
and Moll (xlv) as Naidllus striato-jmndalus, and which has been described and figured by Prof.
Ehrenberg (xl) from living specimens as Gcoponus slelln-horealis. This must be regarded as
in all essential characters a true Poli/stomella ; for, notwithstanding its minuteness as compared
with the larger forms of that type, it presents in a most complete form the canal-system by
which they are specially distinguished, a row of orifices of the diverging branches being
conspicuous externally (in favorable specimens) on either side of each septal band ; it has,
moreover, a solid umbihcal deposit, perforated by canals from which pseudopodia issue in its
living state; its septal aperture, though sometimes a single fissure, is very commonly sub-
divided by transverse bars of shell into a row of isolated pores ; and the whole shell is
covered with an exogenous deposit in the form of tubercles or minute granules, a feature
which is especially apparent in the variety distinguished by Schultze (xcvii) as P. r/ibba.
Moreover we have frequently an indication in this form (which seems like a reduced copy of
P. craticulata) of crenulations along the posterior margin of each of the segments marked out
by the septal bands. The Nautilus faha of Fichtel and Moll is another transitional form
between the typical PotystomeJla and the Nonioninc group ; of which last the Nautitus asteri-
zans of Fichtel and Moll may be considered a typical example. This derives its name from
the radiation of the exogenous deposits from the umbilical region along the septal bands ; a
feature which is still more pronounced in the N. limba of D'Orbigny (Modcles, No. 11), and
which is curiously modified with flaps in his N. stcltifera (v, plate iii, figs. 1, 2). The reputed
species of Nonionina need a careful investigation to ascertain how far they are conformable to
what has here been given (in conformity with the views of Messrs. Parker and Rupert Jones,
Lxxvin) as the true " idea " of a form which has hitherto been so vaguely defined as to
lead some systematists to propose the entire suppression of it as a generic type, whilst others
(ex) have proposed to include in it OpcratVma and Assilina.

GENUS POLYSTOMELLA. 287

484. J^ni/ies.— Although the typical Pohjsiomdla differs so remarkably from any other
known form of Foraminifera, yet in those varieties in which its peculiarities are (so to speak)
softened down, we trace an obvious affinity to the ordinary Operculine type. Thus in P. nixpa
the reduction of the umbilical deposit to what is little more than the large tubercle often
presented by Operculina, the lenticular form of the shell as displayed in a vertical section, and
tlie limited distribution of the canal-system, constitute one set of hnks; whilst in tlie P. slrialo-
jy«;/e/'«fo another set is established in the suppression of the crenulations for the lodgment of the
retral processes, and in the conversion of the cribriform aperture into a continuous slit. Thus
we may regard Poli/sfoiiicUa as a sort of offset from the Nummuline series ; distinguished, in
its highest evolution, by the extraordinary and very regular development of its canal-system,
by the crenulations for the lodgment of the retral processes of the segments, by the excessive
amount and peculiar disposition of the exogenous deposit which forms its supplemental skele-
ton, and by the substitution of a row of separate pores for the single continuous fissure. If,
however, we carefully examine into the value of any of these characters as marking an abso-
lute difference of type, we find that they are all gradational, and are in no instance all com-
bined in the highest degree. Thus the approximation of the canal-system in P. crlsjjn to the
ordinary Operculine type makes it evident that the meridional canals which are so remarkable
in P. craticiilata and P. sfriato-pmdafa are really nothing else than the intra-septal arches of
the canal-system in Opcnul'ma (^ 445) ; and that the rows of diverging branches of the
former correspond with the extension of the intraseptal system into the marginal cord of the
latter, its peculiar modification being related to the marked difference in the disposition ot
the layer of exogenous substance, which in the one case completely invests the external
surface of the shell, whilst in the other it is limited to a narrow marginal band. Again, the
retral processes which constitute the" most distinctive feature of the animal in P. crispa, and
are lodged, not only in grooves but in tubes of its shell, are far less developed in P. craficitlata,
and are almost or completely suppressed in P. ninato-puHctata. The exogenous deposit, which
is generally abundant in P. cratiailata, is sometimes present in a comparatively small amount
both in that and in other forms ; so that its presence or absence affords no proof of essen-
tial distinctness. And the cribriform aperture gives place in the Nonionine modification of
this type to the ordinary Operculine fissure. There is nothing, therefore, to forbid the idea
that this diverging form may have been the result of gradual modification.

485. Geographical Distribution.— This genus has a world-wide range, representatives of
it being found in all seas. The predominant form in the tropical ocean seems to be P.
craticuluta ; in temperate seas it is P. crispa ; and in the arctic zone it is P. striato-piniclata.
The Nonionine sub-type seems to prevail especially in temperate latitudes and in shallower
seas than those frequented by the typical Polystomella.

486. Geological Bistriljulion. — The only example of the typical Polystoniclla that has
yet presented itself earher than the Tertiary period is that described by D'Orbigny
(lxxiii) under the name Fuujasina carinatu (^ 482), which occurs in the Upper Chalk of
Maestricht. With the Eocene period, however, this generic type seems to have become
more widely diffused ; as it occurs in the early Tertiary strata of various parts of the world, and
abounds in many deposits of the middle and later Tertiary periods, its examples being espe-

288 FAMILY XUMMULINIDA.

cially numerous and varied in the Vienna basin and in the Sub-Apennine strata. The geological
distribution of the Kontoniiie sub-type, so far as we certainly know at present, corresponds
closely with that of the typical PolptomrJla -. there are, however, some Foraminifera in the
Carboniferous Limestone of Russia, described by Eichwald, that very much resemble
Konionina.

GcniisX. — Heterostegina (Plate XIX, fig. 1).

487. Hlsiori/. — Although the genus Heterostegina was established by RL d'Orbigny in his
first systematic arrangement of Foraminifera (lxix), its essential structure was altogether misap-
prehended by him, and has been misrepresented by others on his authority. Even in his latest
classification (lxxiv) he continued to rank this genus in his order Entomostet/ues, placing it in
close approximation to Aiiipliisfegina, from which he considered it to be chiefly differentiated
by the subdivision of its principal chambers by transverse partitions. I have had the oppor-
tunity of examining, by the kindness of Mr. Cuming, a very extensive series of specimens of
this type from the Philippine islands ; many of these are of large size, attaining as much
as half an inch in diameter ; and the appearance of the adult specimens scarcely diflers less
from that of the young (which latter are alone figured by M. d'Orbigny), than it does in the
case of Orbiculiiia. The dredgings of Mr. Jukes have furnished me with numerous specimens
of Ilelerosteghui from the Australian coast; these closely correspond with the figures of
M. d'Orbigny, being of comparatively small size, and not exhibiting that peculiar mode of
development which is characteristic of the adult ; and as the Australian forms correspond
precisely with the young of the Philippine, there can be no doubt of their specific identity.
I recognise the shells of the same species as almost the sole components of a fossilized deposit,
evidently belonging to the Tertiary epoch, which is very commonly met with in Malta in
fissures of the rocks, but of which the precise age is uncertain.

488. Eaier/ird Characters. — The older specimens of Heterostegina (Plate XIX, fig. 1)
present a form which, when regular, may be characterised as discoidal, and whicli is almost
perfectly symmetrical ; some degree of twisting, however, is almost constant in the larger
specimens. There is a large umbilical tuberosity, somewhat excentrically placed, from which
the turns of a spire are seen to commence; and the last of these becomes continuous with
one part of the margin of the disk {a, b, c), which there possesses a thick and defined border.
x\s this spire opens out, however, it becomes thinner and flatter; and this thinning is
especially noticeable at that part of tlie margin of the disk [a, J, c) which corresponds witli
the opening of the spire. The whole surface of the disk, except the portion which is occupied
by the umbihcal tuberosity, is marked by septal bands, which follow one another at very
small intervals, and are strongly curved with their convexity anterior. Not unfrequentl)'
these bands do not extend continuously across the convolution, but join themselves to otiier
bands, so that the chamber included between them is more or less incomplete. Between
each septal band and the one whicli succeeds it, the surface is marked by transverse lines.

GENUS HETEROSTEGINA.

289

disposed at pretty regular intervals ; these are similar in appearance to the septal bands, and
are indicative, like them, of subjacent partitions. The septal bands, and these transverse
lines, like the septal bands of Opcrculiita, may or may not be level with the general surface,
being sometimes a little elevated above it, but being always most distinguished by the
non-tubular texture of the shell, which causes them to present a glistening appearance under
reflected light. Small spots of the same substance are occasionally to be seen, as in
Operculina, in the interspaces between the septal bands ; and the umljilical tuberosity
sometimes has in its centre a large round spot of the same kind.

489. Internal Structure. — When we examine, by sections taken parallel to the surface
and passing through the median plane (Fig. XLV), the structure and arrangement of that first-
formed portion of the disk which is hidden beneath the umbilical tubercle, we see that, as in
the helical Forarainifera generally, the first chamber {a) is globular, that the second {b) l)uds

Fig. XLV.

\.

Section of Hclcroslti/iiHf tliiough the mediau plane.

forth from one side of this, and that each successive chamber originates from the outer margin
of the preceding, just as in Operadi/ia or any other simple helical form. But before one turn
of the spire is completed, each newly-formed chamber is seen to have a small portion divided
off (as it were) by a transverse partition near the marginal part of the whorl, so as to consist
of two chamberlets {c, c) ; just about the part where the second turn is completed, the gradual
opening out of the spire gives room for the interposition of a third chamberlet in each row
((/) ; and the number is soon further augmented in accordance with the progressive increase
in the breadth of the spire and the width of the entire chambers, the dimensions of the

37

290

FAMILY NUMMULINIDA.

individual chamberlets retaining a pretty close conformity to a constant average. The
general plan, in fact, bears a very close resemblance to that of OrbicwKna (% 139) or to that
of the spirally-commencing variety of Orhitolites i^ 180). The increase in the number of
chamberlets in successive rows always takes place at the inner margin of the spire ; some
of those nearest the outer margin dying-out, as it were, without giving origin, to new
chamberlets in the next row. This may, I think, be connected with the fact, that there
is always a free aperture (e, e) between one row of chamberlets and the next, at the inner
margin of each spire (the situation of the aperture in Opercniina), and that the chamber-
let which abuts on the preceding whorl is nearly always much larger than the rest of
the chamberlets in the same row, and gives origin to two or even three chambers in the
next row. Further, it is shown by vertical sections (Fig. XLVII), that the innermost cham-
berlets of the whorl are not only deeper but broader, their lateral walls diverging from
each other where they are to be continued over the spire they invest. Hence it is pretty
obvious that this portion of the whorl is that wherein the most active increase takes place ;
and it is here that the marked accession to the number of chamberlets occurs, which tends to
carry the later rows around the whole circumference of the spire, and thus to convert it into
a disk, as in Orbiailina (1 136). After careful and repeated examination of a great number
of sections, I have failed to detect any communication between the adjacent chamberlets of
the same row. The chamberlets of successive rows for the most part alternate with each
other in position ; and each chamberlet seems, as a rule, to communicate (as shown in
Fig. XLVI, a, a) with each of the two chamberlets against which it abuts at either extremity,

Fig. XLVI.

More enlarged portion of a section of Eeierostegina, through the median pKine : a a, communications between the
chamberlets of successive rows ; b, h, canal-system of the marginal cord.

in the manner to be more fully described in Cydochjpeus (IF 496). Thus it would appear
that each new chamber or row of chamberlets is formed by the independent gemmation of
the segments of the preceding row ; and hence it is easy to see why the formation of an
incomplete row should be so much more frequent an occurrence in this type, than it is in
those similarly-complex types in Avhich a free lateral communication exists between the
chamberlets. Each chamberlet is surrounded by its own proper wall, so that the septa which

GENUS HETEROSTEGINA. 291

divide it both from the adjacent chamberlets of the same row, and from the chamberlets
against which it abuts at its extremities, are all double. The latter (forming the septa
between the principal chambers) are strengthened by the interposition of an additional deposit
of shell-substance, forming an "intermediate skeleton ;" but this is scarcely traceable in the
former. There are distinct indications of a canal-system resembling in its general distribution
that which is more fully developed in C//clocl>/peus (T 498); and these are most obvious
(Fig. XLVI, h, h) in the thickened marginal band, which resembles the "marginal cord" of
Operculiua (^ 444), save in its much inferior development.

490. By examining a vertical section, such as is shown in Fig. XLVIl, it is unmistakeably
shown that the spire is perfectly symmetrical, and that each convolution not only surrounds
but completely invests its predecessor. The investing whorl does not, in the younger part
of the spire, come into immediate contact with the two surfaces of that which it includes,
but is separated from it by alar prolongations of the chambers and of their septa, very much

Fig. XLVII.

Vertical section of a youug Heierostegina, showing its symmetrical plau of growtli : a, a, openings between the

chamberlets of successive rows.

as in ordinary Numm/iIi/itB (^ 462), these alar prolongations showing little or no subdivision
into chamberlets. But between the later whorls there are no such interspaces, and the
successive laminte come into absolute continuity with one another ; both the tubuli and the
cones of non-tubular substance being continued from each into the one external to it. From
the time that the rapid thinning-away and opening-out of the spire commences, the investment
of the previously formed whorls seems to discontinue ; the spiral lamina of the last whorl
being merely applied to the external margin of that of the penultimate (as in OjxrcuUi/a, % 442),
instead of being continued over its surface.

491. JJjfiJiities. — It is obvious from what has preceded, that Heterostc/jina bears precisely
the same close relation to Operculina that Orhicid'ma bears to PeneropUs ; the subdivision of
the principal chambers into a row of chamberlets, by partitions extending transversely from
each septum to the next, being the essential character of difference in each case. The
relation of analogy between Heterosteghia and Orbiculiiia is extremely striking ; since in each
type the earlier convolutions invest those which precede them, whilst the later extend
themselves peripherally instead of centrally, and the mouth of the spire or " apertural plane "
widens on each side so as to pass round (it may be) the whole circumference, and tlius to

292 FAMILY NUMMULINIDA.

convert the spiral into the cyclical plan of growth. But the differences between these two
types in regard to the texture of the shell, the mode of communication of the chambers and
charaberlets, and the presence or absence of an intermediate skeleton and canal system, are
such as most widely to separate them in any classification that is founded on characters of
true physiological value. The affinity of Ileferostegina to Cyclocli/peits again, is extremely
close ; the conformity of these two types, as regards every point of minute structure, being
complete ; and their difference being precisely that wiiich exists between OrhkuVma and
Orhifolites, — namely, that of the earlier plan of growth, which, in the former case, is spiral,
with a tendency to the cyclical, whilst in the latter it is cyclical from the beginning. To
Amphistegina, on the other hand, the relationship of this genus is very remote.

492. GeograjjMcal and Geological DisfribuHon. — The genus Ilcferostegina is at present
known only as an inhabitant of tropical and sub-tropical seas ; having been found near
various parts of the East Indian, Australian, Polynesian, and West Indian shores, but not in
any colder latitude.— No other fossil examples of Hderosiegina have yet been met with, than
those which present themselves in the Vienna Tertiaries, in the Maltese deposit already
adverted to, and in a limestone apparently of Tertiary age on the south-east coast of
Arabia, in which Mr. Carter (xxiii a) has found HeterostegintB together with Orbitoides
and Cydoclypeus.

Genus VI. — Cycloclypeus (Plate XIX, figs. 2 — 7).

493. Historg. — This genus, first instituted by myself (xiv), is among the most interesting
of all the Foraminifera at present existing, on account botli of the large dimensions which it
sometimes attains, and of the light which its structure throws upon that of various fossil
types. The only specimens of it yet known were dredged by Sir Edward Belcher from a
considerable depth of water off the Coast of Borneo. Two of these, which are now in the
British Museum, are complete circular discs, measuring no less than 2\ inches in diameter ;
and by the kindness of Dr. J. E. Gray I have had the opportunity of making microscopic
sections of a fragment of a disk, which, when entire, must have nearly equalled these in size.
Smaller disks of various dimensions presented themselves in the same dredgings.

494. External Characters. — The external aspect of these disks is sufficiently like that of
Orbifolites to prevent the two genera from being readily distinguished by a superficial
examination, especially when young specimens of Cgcloclgpeus are compared with OrbitoUtes
of the complex type ; since, on the two surfaces of the former (Plate XIX, fig. 2), there can
be distinguished concentric rings of oblong chambers, which are not at all unlike the
similarly disposed superficial cells of the latter. The peculiarly compact texture of the shell
of Cgcloclgpeus, however, gives to its surface a smooth and glistening appearance, which is very
different from that of Orbitoliles ; while the annular divisions and the radiating subdivisions
are indicated not so much by any inequahty of the surface (though they are usually somewhat

GENUS CYCLOCLYPEUS. 293

elevated), as bj' the substitution, along the septal lines, of the hyaline non-tubular sliell-
substancc for that which is rendered opaque by its tubularity '{% 58). And further, the
forms of the two genera ordinarily differ in this — that whilst the centre of Orbitulifes is
usually rather depressed than elevated, and the thickness of the disk generally increases
towards the periphery, the central portion of Cyclodypem always presents a knobby elevation,
on the surface of which the oblong boundaries of the chambers are superseded by rounded
spots of non-tubular shell-substance (sometimes rising into tubercles), whilst the thickness of
its disk gradually diminishes towards its margin, where it is so I'educed as to come to a sharp
edge. In older specimens of Cydodiipeus, the boundary markings of the chambers are scarcely
distinguishable, save near the margin ; their concentric annuli are marked out, however,
by rows of spots resembling those of the central eminence, which will be presently shown
(*]y 497) to be the bases of cones of non-tubular substance (fig. 5, d, d, d). In either
case, it is usually observable that the breadth of the annuli is far from constant, and that the
annuli are not unfrequently incomplete, extending round only a portion of the disk. This
irregularity has been noticed in OrbifoUtes (^ 171) as of rare occurrence; in Cijdodypeii>i it is
so common that I have not yet met with specimens which are entirely free from it.

495. Internal Structure. — Whilst agreeing with Orbitolites in those external features
which result from the cydical mode of growth that is common to both forms, Cydodypeus
presents as wide a contrast to it in every other feature of its organization, as is anywhere
known to exist within the limits of the Foraminiferous group. On making horizontal and
vertical sections of the Cydodypeus disk, its central plane is found to be occupied by chambers,
disposed (ordinarily in a single layer) in concentric annuli ; these are covered-in above and
beneath by compact plates of shell, which are thicker towards the centre, thinner towards the
circumference (Plate XIX, fig. 2). The typical form of these chambers seems to be a parallelo-
gram with its angles rounded off, whose sides are to each other as I5 to 1, or as 2 or even 3 to I,
the longest side lying in the direction of the radius of the disk ; but owing to the variation
in the leiiyth of the chambers which results from the before-mentioned irregularity in the
bi'eadth of the annuli, the breadth of the chambers remaining more constant, their pro-
portions vary greatly in diflerent parts of the same annulus, or in adjacent parts of different
annuli, as shown in fig. 7. I have occasionally met with chambers whose length was to their
breadth as 4 to 1 . The vertical thickness or height of the chambers seems usually to be
pretty constant in different parts of the disk, except near its centre ; the thinning away
towards its margin being due, not so much to a diminution in the vertical height of the
chambers, as to the reduction of the thickness of the shelly plates that enclose them above
and below. But although the existence of only a single layer of chambers is obviously the
rule in this type, yet exceptions to it are not unfrequent ; a subdivision of the entire stratum
into two or even three presenting itself when its thickness is above the average ; whilst
occasionally one or two chambers only are thus subdivided.

496. The cavity of each chamber is surrounded by a proper wall of its own, quite
distinct from that of the chambers which it adjoins ; and hence the septum by which each
chamber is divided from the adjacent one on cither side, is formed of at least two lamella;.
These come into close contact with each other at the junction of the vertical septum with the

294 FAMILY NUMMULINIDA.

horizontal roof and floor of the chamber ; but elsewhere they diverge from one another,
leaving an interseptal space, which is partly filled up by an interposed lamina of shell-
substance, but is partly occupied by the inferscpfal canals to be presently described
(fig. 5, h, h, li). A thicker space of the same kind is in like manner left between the proper
walls of the chambers forming one annulus, and those of the chambers forming the annuli
internal and external to it ; this space is almost entirely filled up by a shelly deposit, the
interseptal canals which pass between the successive annuli being less numerous than those
which run between the chambers of the same annulus (H 498). This intervening deposit
constitutes the " intermediate " or " supplemental " skeleton of this type. As in Orbifolites,
the chambers of each annulus usually alternate in position with those of the annuli internal
and external to it. But this is by no means constantly the case ; since additional chambers
are ' interpolated' here and there, so as to increase the number according to the augmented
diameter of the annulus ; and such an interpolation disturbs the regular arrangement of the
neighbouring chambers. The adjacent chambers of the same annulus have not, so far as I
have been able to ascertain, any direct communication with each other ; an indirect com-
munication, however, is perhaps established through the system of interseptal canals. But
each chamber normally communicates with two chambers of the annulus within it, and also
with two of that which surrounds it, by large passages (shown in horizontal section in
fig. 7, a b, a b, a b, and in vertical section in fig. b,f,f,f, and as seen in perspective view in
fig. 5, ff, (/), which traverse the annular septa ; of these passages there are generally two, and
occasionally three, one placed directly or obliquely above the other, for each pair of chambers
thus to be brought into communication. Thus at each extremity of the oblong chamber,
there are normally two passages on one plane (fig. 6,/;/) leading to two chambers (c, c , d, d')
in each of the annuli next internal or external to it ; but since to each of these chambers
there may be two or even three passages on different planes, the total number at each end
may be foui-, five, or six. But since, on the other hand, each of the 'interpolated' chambers
communicates with only one chamber in the annulus next internal to it, it will have but
a single set of passages in place of two.

497. The shelly plates which enclose the chambered plane above and below, are formed of a
succession of superimposed lamellse (figs. 2, 5). These lamelte, which are of tolerably uniform
thickness, are most numerous in the older or more central portions of the disk, and diminish
in number towards the marginal or last-formed portions ; so that it seems pretty certain that
new laraellse must be added from time to time, as the disk is augmented by the formation of
new annuli. I have often met with appearances which might seem to indicate that the
formation of a new lamella over the entire surface of the disk, and the addition of a new
annulus at its margin, were parts of one and the same act of growth, the new lamella being
continued into the annular septum ; but if this were constantly the case, the number of
lamellre which form the ceiling or floor of any chamber would always correspond with the
number of annuli internal to it, which I do not find to hold good. Each of these ]amell?e is
perforated by an assemblage of parallel tubuli very closely set together, which pass from its
inner towards its outward surface (figs. 3, 4) ; and there is such a continuity between the
tubuh of successive lamellae, that a communication is thus established between the
cavity of the thickest-walled chamber and the external surface of the disk. These tubuli,

GENUS CYCLOCLYPEUS. 295

however, are very minute, their diameter being not above 1 - 1 0,000th of an inch. They are
wanting in certain parts of the shell [a, a), which there presents a transparence that contrasts
strikingly with the semi-opacity produced by the tubular perforations. By the comparison
of vertical with horizontal sections taken in difterent planes, it appears that these non-tubular
portions of the shell have a conical form, the base of each being on the surface of the shell,
and its apex pointing to one of the angles at the outer margin of a chamber (fig. 5, c c, d d).
Their gradual widening towards the surface causes the diameter of their bases to increase
with every addition to the thickness of the shell ; and thus it is on the older portion of the
shell, and especially on its central protuberance, that they become most conspicuous as
rounded spots, sometimes rising into tubercular elevations (1 494) . In horizontal sections of
the superficial lamellas, they form a large proportion of the area ; whilst in similar sections
near the chambered plane they become blended with angular projections of the annular
partitions, whicli fill up the spaces left between the proper walls of the chambers by the
rounding-off of their angles (as shown in fig. 4). The lamellated structure is seen in these
conical pillars (fig. 3, a, a), the lamellae being continuous with those of the tubular part of
the shell ; so that at each increase in thickness a tubular and a non-tubular portion must be
superimposed upon the corresponding parts of the preceding lamella. Both in the tubular
structure of the shell, and in the presence of these non-tubular columns, there is an exact
conformity to the structure of Nummulina, OpercuJijia, &c.

498. I have now to speak of the system of iidersej}fal ciuiah, which is traceable
throughout the whole of the solid skeleton, though less regularly distributed than in some
of the preceding types. It may be conveniently described as consisting of radial, vertical,
and annular canals. The radial canals are seen both in vertical and in horizontal sections
(fig. 5, h, h ; fig. 6, y, //,) excavated in the shelly substance which is interposed in the
radiating partitions between the proper walls of adjacent chambers of the same annulus.
When the canal reaches the end of the radial septum, it usually subdivides into two, which
diverge at a considerable angle from each other, so as, by traversing the annular septum, to
reach the two alternating radial partitions of the next annulus ; and as each branch, before
entering the partition (fig. 6, i, /') towards which it runs, unites with another branch that inclines
towards it from the radial canal next adjacent. It follows that just as every chamber com-
municates (normally) with the two alternating chambers in the annuli internal and external
to it, so do the interseptal canals of every radiating partition communicate with those of the
partitions alternating with it in the internal and external annuli. In each radial partition
there are at least two, and very commonly three tiers of such canals, and sometimes they
are yet more numerous (fig. 5, i). Short transverse branches, apparently communicating
with the cavity of the chambers (fig. 6), are sometimes seen to proceed from the longitudinal
canals ; in regard to these communications I would not speak with confidence from what I
have seen in Cijdoclypeas ; but that they exist in other organisms is unquestionable. The
horizontal radiating canals communicate (as at g ■, g, fig. 6) with vertical canals, which ^^ass
directly towards the two surfaces of the disk, whereon they open ; these canals are best seen
in horizontal sections taken near the upper or under surface of the chambers (fig. 4), in
which they present themselves in regular rows, c, c, corresponding to the radial partitions ;
whilst in similar sections taken nearer the surface they are seen to be less regularly disposed,

296 FAMILY NUMMULINIDA.

in consequence of their following a somewhat oblique direction. Still their continuity
is maintained through all the successive layers of which even the thickest part of the
shelly disk may be composed, and they open upon the surface along the borders of the
septal bands or spots of non-tubular shell-substance (fig. 5, e, e). The annular system
of canals traverses the thick band of shell-substance that usually intervenes between
the successive annuli, and is continually brought into view in horizontal sections
(fig. 6, h li, Ii! H). It appears from vertical sections traversing the annular septa, that
several tiers of these annular canals may exist. I have frequently ti'aced them running con-
tinuously for a considerable distance, without appearing either to give off any branches, or
to communicate with the radial canals ; but I have occasionally seen appearances which
indicate that such a communication is estabhshed by means of canals passing vertically
downwards at the angles of the chambers, so as to unite the three sets of canals into one
continuous system, furnished with a multitude of orifices upon tlje surface of the disk. A
representation of the whole canal-system, as I believe it to exist in this organism, is given
in fig. 5.

499. Monstrosities. — Although the number of specimens of this type which I have had
the opportunity of examining is but small, yet two among them exhibited the same kind of
monstrosity as that which is common in Orhitolites ; namely, the superposition of a vertical
plate upon the horizontal disk (If 181). And in each it is sufiiciently apparent that this
plate has originated from the central cell, and that its increase has taken place pari i)assu
with that of the horizontal disk.

500. AJfmiiies. — There cannot be a better case than that which is afforded by the type
under consideration, for testing the relative values of a classification based upon plan of
yrowtk, and of one based upon the internal structure of the sJiell, as affording the key to the
natural affinities of an organism for which a place has to be assigned ; and it will, therefore,
be worth while here to review the principal facts relating to the structure of Cycloclypeus, and
to compare them with those furnished by Orbitolitcs and its allies on the one hand, and by
Ninnmulina and other members of the Nummuline series on the other. The sole point of
resemblance between Ci/clocli/pci(s and Orltitolites consists in this — that the mode of growth
is cyclical, the extension of the disk being effected by the formation of successive annuli,
each of which is divided by radiating partitions into secondary chamberlets. But it has been
shown that the lateral communication between the chamberlets of each annulus of the simple
type of Orbitolitcs is so free, that the sub-segments of the animal body which occupy them
are simply beaded enlargements of the continuous annular stolon that constitutes the
principal segment ; and that it is from the intermediate portions of that stolon, not from the
sub-segments, that the radiating extensions issue which go to form a new annulus. In
Cyclochjpeus, on the other hand, the chamberlets of each annulus are completely cut off from
direct communication with each other laterally, opening only into the chamberlets which lie
next them in the central and pei'ipheral directions ; so that the adjacent sub-segments forming
each annulus have no mutual connection, and their extension in a radial direction by means
of the extensions they put forth will take place with entire independence, except as regards
the coalescence of these radiating stolons after they have issued from the marginal pores.

GENUS CYCLOCLYPEUS. 297

This independence is strikingly manifested by the frequency with which incomplete annul i
are added to the previous margin of the disk, extending (it may be) along not more than a
third, a half, or two thirds, of the entire circumference. Thus the growth of Cjjclucli/peu.i is
in reality rather radial than cyclical ; the formation of concentric rings being simply due to
the fact that the sub-segments occupying the last-formed annulus of chamberlets are for the
most part ready to originate a new series of chamberlets at the same period. This restriction
of the communication between the different parts of the sarcode-body, which is in such
marked contrast with the extreme freedom that prevails throughout OrbifoUtes, is probably
related to the circumstance that whilst the aggregate animal of the latter is nourished by the
pseudopodia protruded through the marginal pores alone, each sub-segment of the former
may imbibe its nutriment by pseudopodia passing through the tubuli of the walls of its own
chamber (^ 59). Tiiat these tubuli, notwithstanding their minuteness, serve for the passage
of pseudopodia, and that these pseudopodia may coalesce on the exterior of the disk into a
layer of sarcode forming a continuous investment of its surface, appears from the fact that
successive laminre are added to the e.rfcrior of the shell, the tubuli of which are continuous
with those of the laminae to which they are applied, — a fact which can scarcely be explained
on any other supposition.

500. Thus, then, whilst in the isolation and independence of the subdivisions of its
body, in the enclosure of each of them in its own proper wall, in the interposition of an
intermediate skeleton and of a canal-system between the contiguous walls of adjacent
chamberlets and annuli, and in the minutely-tubular structure of the shell, — all of them
points of high physiological importance, — Cycloclijpeus agrees with Operculina and other forms
of the Nimimidine type, its only point of accordance with OrbifoUtes or any member of the
MUioline type is the subdivision of its principal segments into sub-segments, and the multi-
plication of these upon a plan which is essentially cyclical. But the subdivision in question
is common, as we have seen, to all the principal types of Foraminifera ; and we have already
seen it presented in the Niniimidine series by Heferoster/iiia, the relation of whose chamberlets is
exactly the same as that which exists in Cycloclypeus. The affinity between these two forms,
in fact, is as intimate as that between Orbiculina and OrbifoUtes (^^ 143, 183), and is of
precisely the same nature ; for peripheral fragments of these two organisms could not be
distinguished from each other ; and the tendency of the later stages of growth in
Hefcrosfecjina, as in Orbiatfina, is to a change in the mode of increase, by the lateral
extension of the growing margin, from the spiral to the cyclical.

501. Geographical and Geological Distribution. — We have at present no knowledge of the
present existence of Cgcloclj/pci/s in any other locality than that already mentioned (^ 493) ;
and no other examples of it have yet been discovered in a fossil state than those stated by
Mr. Carter (xxiii a) to occur in company with Orbiluides and Heferosfet/ina, on the south-east
coast of Arabia, in a white limestone apparently belonging to the early Tertiary epoch.
The structure of one of Prof. Ehrenberg's " casts " (Plate XXII, fig. 5) is in every
respect so conformable to that which would be presented by the body of Cgcloclj/peus, in
regard to the communications between the segments and the interseptal system of canals (as

38

298 FAMILY NUMMULINIDA.

shown in Plate XIX, fig. 6*), as apparently to indicate the existence of this genus at the
Nummulitic epoch to which these casts are to be referred ; but, as will presently appear,
this cast may not improbably represent a portion of the median layer of Orhifoides.

Genus VII. — Orbitoides (Plate XX).

502. History. — The genus Orbitoides vidiS first instituted by M. D'Orbigny in 1847 for
the reception of a peculiar fossil brought from the United States by Sir C. Lyell, who had
noticed it ('Quart. Journ. of Geol. Soc.,' vol. iv, p. 12) under the name of Nmnmulites
Mantelli previously conferred upon it by its discoverer Morton. I have not, liowever, been
able to discover that M. D'Orbigny gave any definition of the genus previously to the pub-
lication of the second volume of his 'Prodrome de Paleontologie Stratigraphique ' (1350), in
which he characterises it by a portion of tlie description which he afterwards (1852) more
fully gave in his ' Cours Elementaire ' (torn, ii, p. 194). It was then first that he instituted
the order Cydostegues, in which he ranked Orbitoides in sequence to Cyclolina, Orbitolites, and
Orhitolina, distinguishing it from those genera by the following characters : — " Coquille
discoidale convexe des deux cotes, formee d'une seule rangee des loges autour du disque ;
test fortement encroutc exterieurement au milieu, et montrant soit des lineoles rayonnantes
soit des granulations." Some time previously, however, I had given (xii) a nearly complete
description of the Orbitoides Mantelli ; and had further shown that a form of which small
specimens had been previously described under the name of Orbitolites Prattii (probably the
" Discolit/ius, IV, a," of Fortis), as well as the Lycophris epldppium and L. dispansus of Sowerby
(' Geol. Trans.,' 2nd ser., vol. v, pi. xxiv, figs. 15, 16), were all referable to the same type.
The genus has been adopted by Mr. Carter, who, however, in the first instance (xix), mis-
conceived its true structure (affirming its mode of growth to be spiral instead of cyclical), and
who now (xxiii «t) rejects from it the very type on which the genus was founded, referring
it (on fallacious grounds, as I shall presently show) to the genus Orbitolites. The genus has
also been adopted by MM. D'Archiac and Haime (i), and by Bronn (xi), who, however,
re-names it Hymenocyclus, objecting to Orbitoides as a hybrid word.

503. External Characters. — It is impossible to discriminate Orbitoides from Nummulina
by external characters alone ; for although the most characteristic forms of each type cannot
be mistaken for each other by any one who has familiarised himself with their respective

* The very close conformity of this somewhat diagrammatic representation to Prof. Elirunberg's
figure, might suggest the idea of its having been derived from the latter. But the former had been
constructed by Mr. G. West, from specimens prepared by myself, long before the publication of Prof.
Ehrenberg's researches.

t I think it well to state that Plate XX had not only been drawn, but printed, before I became
acquainted with ^Ir. Carter's later researches.

GENUS ORBITOIDES. 299

aspects, yet specimens are often met with in which all distinctive features are so completely
wanting, that nothing save an examination of their internal structure can enable their real
nature to be determined with certainty. The typical form seems to be a flattened lenticular
disk, as represented in Plate XX, fig. 1, which very closely resembles that of the thinner
Nummulites, except in the relatively greater convexity of the central region, — in this respect
corresponding closely with Cydodypnis (Plate XIX, fig. 2). This convexity sometimes
increases so remarkably that the central region becomes almost globular, whilst the peri-
pheral thins-out and becomes almost flat, as in the ibrm delineated by Sowerby (loc. cit.) as
Lycophris dispansits. In other instances, on the contrary, the convexity of the central is not
greater than that of the peripheral portion ; the form being then so regularly lenticular as
to afford no means of distinguishing such an Orhiloides from a Nummulite. Again, the disk,
instead of being lenticular, may be nearly as flat as a piece of money, being commonly of the
like proportionate thinness, but sometimes as thick as two or three ordinary coins laid one
upon another ; in either of these cases, however, there is usually a central tubercle that serves
to mark the type ; and the thinner forms are frequently reduced to extreme tenuity at their
margin, whilst the margin of the thicker is abruptly rounded-off with little or no previous
reduction. The thinner forms are often more or less contorted, and not unfrequently they
assume a regularly ephippial shape, as in \he Lycophris ephippimi of Sowei'by (loc. cit.). I am
disposed to think that such contortion is due to the inequality of the surface to which the
specimens were attached during life ; for in a specimen from Biaritz kindly presented to me
by Mr. S. P. Pratt, it was pretty evident that the organism had spread itself irregularly over
a rock, after the manner of an incrusting Zoophyte. — The only surface-marking that can be
distinguished, and this only in well-preserved specimens, is an irregular areolation, in the
midst of which rounded tubercles of variable size are often disposed. These tubercles are
sometimes of a more opaque white than the rest of the disk ; whilst sometimes, on the other
hand, they have an aspect of greater transparency. Not unfrequently they occupy the
centres of groups of areolse, which are quincuncially disposed around them, as is shown at
e, e, fig. 2, Plate XX. In the smaller and thinner specimens they are most commonly
absent, or, if present, they are comparatively few and insignificant. The presence of the
tubercles alone would not serve to differentiate an Orbitoides from a Nummulina ; but the
areolation, when distinguishable, is a positive character, since nothing like it is ever pre-
sented even by the " reticulate " Nummulites.

504. Infernal Structure. — The disk of Orlj'itoides essentially is composed (Plate XX,
fig. 1) of a median plane of chamberlets arranged cyclically round a large central chamber;
and of numerous layers of flattened chamberlets, having neither regularity of form nor
systematic plan of arrangement, that are interposed between the multiple lamellre of shell
which enclose the median plane of chamberlets on either side. — Although the chamberlets of
the median plane are disposed in concentric annuli, yet these annuli are often incomplete, as
shown in Plate XX, fig. 1 ; thus bearing a much closer resemblance in arrangement to those
of Cycloclypeus (H 499) than to those of Orhitolitvs (t 171). There is so decided and constant
a difference as regards the form of the chambers between 0. Mantclll and 0. Fortinii, that,
until such a gradational series of connecting links shall be discovered as unites the similarly

300 FAMILY NUMMULINIDA.

diversified varieties of OrhUolites (If 1 78), they must be retained as distinct species. The cham-
berlets of the former are nearly as cylindrical as are those of the simple type of OrhUolites,
being sometimes slightly flattened against the margin of theannulus within, as shown in fig. 5,
and sometimes rendered hexagonal by mutual pressure, as shown in the lower part of fig. 9.
The chamberlets of the latter, on the other hand, are rectangular, and are generally con-
siderably longer in the radial direction than they are in the tangential, as is shown in figs.
1, 3, 14 ; the proportion of these two dimensions, however, varies greatly in different annuli,
and even in different parts of the same annulus, as I have shown to be the case in
CycJodypeus (1 495). The height of the chamberlets, that is to say, the thickness of the
median layer, is no less inconstant than in the simple type of Orbifolltes (^ 157); sometimes
being pretty uniform throughout the disk, especially in 0. Foriisii; sometimes, on the other
hand, increasing and sometimes diminishing from the centre to the periphery (see Plate XX,
figs. 1, 7, 10, 11*^).* The typical arrangement of the chamberlets in both species appears to
be alternate in successive rows, as in other cyclical Foraminifera ; but this arrangement,
shown in figs. 3 and 5, is very often departed from. When examined with a sufficient mag-
nifying power, the partitions between the chamberlets are seen (in well-preserved specimens)
to be double, each chamberlet being everywhere surrounded by its own proper walls (figs. 3, 5) ;
and indications of a canal-system are distinguishable in the interseptal spaces left between
these. Each chamberlet normally communicates by oblique passages with two chamberlets in
each of the adjacent annuli. These passages are shown at a b, a b, fig. 5, as they present
themselves in sections that traverse the median plane of 0. Maidelli ; and it is observable
that, like the two divergent passages which in like manner connect the columnar chambers
in the complex type of Orbitolltes (IT 168), those of the same pair are not on the same plane,
so that sometimes one of them is not brought into view by the section that displays the other.
1 have usually obser\ed three pairs of such passages, one above the other, between eacli
chamberlet and the two alternating chamberlets of the next annulus, as is shown in vertical
section at c, c, fig. G ; and these seem to be the six "radiating sarcodal channels" described
by Mr. Carter, (xxiii a, p. iiSO), of which he states that the orifices are distinguishable at the
margin of the test, arranged in zigzag one above the other, as in the complex type of
Orbitolitcs. Similar communications exist between the rectangular chambers of 0. Fortisii,
as represented at c, c, fig. 2, and as shown in the "cast" delineated in Plate XXII, fig. 5,
which seems very likely, from its geological position, to belong to this type, to which it is
referred by Professor Ehrenberg. I have not been able to distinguish in 0. Furti-s/i, any more
than in Cjjcloclijpeus, any indication of lateral communications between the adjacent cham-
berlets of the same annulus; and Mr. Carter seems to have been equally unsuccessful. In
0. Manfelli, however, such a lateral communication seems to exist close to the inner side of
each chamber, as shown in fig. 5 and in the lower part of fig. 8 ; and along this it may be
presumed that a continuous stolon of sarcode passed, like one of the annular stolons of

* By Mr. Carter it is affirmed (xxiiio, p. 329), that tlie chamberlets of 0. Afffw^e/Ziincrease
considerably in height from the centre to the circumference, wliilst those of 0. Fortisii (liis
0. dispansa) present no sucli increase. I cannot but think, however, that the examination of a larger
variety of specimens would have caused him somewhat to modify this statement.

GENUS ORBITOIDES. 301

OrbitoHtes, so as to unite all the chamberlets of the same circle. If the " cast" represented
in Plate XXII, fig. 3, be really that of an Orhi hides, it appears to afford a confirmation of
this inference ; for we there see annular stolons* passing along between the successive rows
of sub-segments, on a different level from the radial peduncles, of which it will be seen that
usually only one shows itself at each extremity of the sub-segment.

505. The shelly layer by which each of the lateral surfaces of the median disk is
covered-in, is nearly always thickest in the centre, thinning away more or less gradually
towards the margin, as shown in figs. 1, 7, 10, 1 1*. In some of those large, thick specimens
of 0. Fortisii, however, that occur in Scinde, in which the thickness of these superficial
layers is very great in proportion to that of the median layer, there is little or none
of such thinning-away towards the margin ; and occasionally we find the margin itself
to be covered-in by an extension of the outer portions of these superficial layers, which meet
each other in such a manner as completely to enclose the median layer and the inner portions
of the superficial layers, as is shown in fig. 15. This extension seems to mark the full
growth of the disk, and may be considered analogous to the closing-in of the spire of Niou-
mulina. — Each of these superficial layers is made up of a number of lamellae, having inter-
spaces between them, which are divided into flattened chamberlets by partitions formed by a
thickening of the lamellae, as shown in figs. 1, 2, 4, 6, 16. The form of these chamberlets
is very irregular, as shown in fig. 4, in the upper parts of figs. 8, 9, and in figs. 12, 13, 14 ;
it bears no relation whatever to the form of the chamberlets of the median disk ; and there is
no constant difference between the forms presented by 0. Mantelli and 0. Fortisii respectively.
These chamberlets are usually much flattened in the direction parallel to the median plane,
so that the thickness of many of them piled one on the other would not equal that of the
chamberlets of the median disk, as in shown in 0. Mantelli in fig. 6, and in 0. Fortisii in
fig. 16. But sometimes their height is considerably greater in proportion, and may equal, or
even surpass, that of the chamberlets of the median disk, as in the specimen of which a
vertical section is shown in fig. 11*. These chamberlets are usually ai'ranged in piles, one
upon the other, as is shown in figs. 2, 11, 16 ; and this arrangement seems to be peculiarly
definite when the superficial layers are traversed by the cones of non-tubular substance pre-
sently to be described. The chamberlets forming any one of these piles usually alternate in
level with those of the adjacent piles ; and each of them communicates by a pair of oblique
passages with two chamberlets, one lower and the other higher than itself, in each of the piles
surrounding its own, as shown in figs. 2, 6, 11. These communications are seen also, as brought
into view by a section parallel to the surface, in the upper part of fig. 9. The lamellae of
shell which form the floors and ceilings of these flattened chamberlets are themselves tubular,
as showm in figs. 2, 4, 6. Their tubuli are not so minute or so closely set as those of
Niimmtilina, OpermUna, or Ci/cloclypeus ; but they are much less coarse, on the other hand,
than those of Tinoporm, the arrangement of whose piled chambers is almost exactly similar
(t 394). This tubular structure (it seems desirable to mention) is often obscured, as in

* I am by no means certain that these are not really the lepi-esentatives of annular canals
passing along interseptal spaces, rather than of stolon-passages uniting tlie cavities of the
chambers.

302 FAMILY NUMMULINIDA.

• Nummuliles, by the changes in the texture of the shell which have taken place in fos-
silization.

506. In both forms of Orbitoides, and not (as stated by Mr. Carter) in 0. Fortisii only,
we often find the superficial layers traversed by columns of non-tubular substance, which are
of conical form, having their bases on the two surfaces (where they commonly form prominent
tubercles), whilst their apices rest on the vertical partitions of the chambers of the median layer
(fig. 2, e, e). These columns are most developed in the large, thick 0. Fortisii of Scinde, in
which they are both large and numerous (figs. 10, 11) ; and being usually rendered opake by
pecuhar changes in fossilization, they present the appearance, in sections parallel to the
median plane, of opaque spots, e, e, figs. 12, 13, the diameter of which in proportion
to that of the chamberlets varies according to the depth at which the section has passed,
being of course greater as its plane is nearer to the surface. In the small, thin varieties of
this fossil which present themselves abundantly in Southern Europe, the columns are
frequently wanting altogether, and if present are very insignificant in size. In the American
variety of 0. Mantelli I have not met with any indication of the presence of these columns ;
but they are very conspicuous in some of the Scindian specimens of that type, although
entirely absent in others, — this variation in their development being in harmony M'ith the
similar variation that occurs among Nummulites. The columns, when present, always occur
at the points of junction of three or more of the partitions between the chamberlets, as is
shown in figs. 2, 12, 13, 14, and may be regarded as formed by an augmented development
of shell-substance at those points, as shown at e, c, fig. 16. When they are brought into
view by vertical sections of thick specimens, it very often happens that they are only
traversed by the plane of section for a part of their length, as shown in figs. 10, 15 ; but it
must not be supposed that they really stop short, as they seem to do, since there can be no
reasonable doubt of their continuity through the successive laminoe of the superficial layer,
as shown in the lower part of fig. 10.

507. The indications of a canal-system which I have met with in 0. Fortisii have been
sufficient, when interpreted by the distribution of that system in Ci/docypeus, to justify the
belief that it is essentially the same in the former case as in the latter. I have been able
clearly to make out annular canals intervening between the successive rings of chamberlets,
and cross branches connecting these which run between the two lamella; of the partitions
between the chamberlets, as shown in fig. 3; and I can also perceive indications (as in
figs. 10, II), that the conical columns were traversed by branches of the same system, which
pass in them towards the surface. Even in the partitions between the superficial chamberlets
I have been able to detect traces of canals (shown in the upper part of fig. 9), just as in the
partitions that subdivide the alar prolongations of the chambers of the reticulate Nummulites.
The interseptal canal-system of the median plane is nearly as well displayed in the " cast"
represented in Plate XXII, fig. 5, as it is in my ideal figure of that system in Ci/cloc/i/pei/s
(which was drawn without the least knowledge of Prof. Ehrenberg's casts) ; so that if the
former really represents an Orbitoides, which there is no reason to question, the entire con-
formity in structure between the median chambered planes of these two organisms is extra-
ordinarily close. — I have not succeeded in making out the canal-system of 0. Mantelli with

GENUS ORBirOlDES. 303

the same distinctness. It seems to form a reticulation which includes each chamberlet in
one of its meshes, as shown in fig. 5 and in the lower part of fig. 9 ; but I have not been able
to satisfy myself of the existence of distinct annular canals.*

508. Affinities. — In the general plan of structure of Orbifoidefi we are reminded on the one
hand of Ci/cloclj/pci/s (Plate XIX, fig. 2), and on the other oi Nnmmiilina (Plate XVIII, fig. 9) ;
for (as will be apparent on a comparison of the figures just referred to) if the superficial
chambers of an Orbitoides were obliterated by the approximation of their laminse, it would be
converted into a Ci/cJocIypeus ; whilst, on the other hand, if its growth were spiral instead of
cyclical, it would come to resemble one of those Kiunmidinm in which the alar prolongations
of the chambers have been broken-up into insulated chamberlets by the inosculation of their
septa. This is much more than a mere superficial resemblance, such as exists between the
arrangement of the chamberlets of the median plane in Cyclodypcus or Orbitoides, and that of
the chamberlets of the disk of the simple type of Orbitolites ; the affinity of Orbitoides to
Ci/clocli/peus and to Niciiimidina being marked by its approximation to those types in all the
characters which have been heretofore specified as of the most fundamental importance, such
as the minutely tubular structure of the shell, the doubleness of the septa (each chamber
possessing its own proper wall), and the interposition of a canal-system between their two
lamellpe. In all these particulars it is equally removed from Orbitolites, with which it has
nothing whatever in common save its cyclical plan of growth, and the mode of communication
between the chambers of its median disk which appears to exist in 0. Mantelli.-\ In the
arrangement of the chamberlets of its superficial laminae, Orbitoides is so closely related to
certain forms of Tinoporus (Plate XV, figs. 3, 4), that if the chambers of the latter were
more compressed vertically, and were more completely differentiated from those of the median
plane, they would resemble those of Orbitoides in every essential particular save the want of a

* In the description of the canal system of 0. Mantelli given by Mr. Carter (xxiii a, p. 330)
there seems to me a confasion which I am unable to unravel, between the apertures which connect
the cavities of the chambers and gave passage during life to stolons of sarcode that united the segments
of the body, and the system of interseptal canals which has little connection with the cavities of the
chambers, being confined to the spaces between the two lamellae of their partitions.

t I must confess myself at a loss to understand the grounds on which Mr. Carter considers that
0. Mantelli should be removed from this genus and placed in near proximity to Orbitolites, though he
would no longer (as formerly) rank it with that type. There is absolutely no difference that I can
discover between the superficial layers of the 0. Fortisii and the O. Mantelli ; the diflerence between
the forms and proportions of the chamberlets of the median plane iu these two types are clearly of
not more than specific value, even if they amount to that ; and if there should prove to be a lateral
communication between the chamberlets of O. Mantelli which does not exist between those of
O. Fortisii, and the canal-systems in the two types should prove to be distributed on distinct plans
such differences would assuredly not render necessary the generic separation of organisms which
resemble each other so closely in all other respects. In approximating 0. Mantelli to Orbitolites, it is
clear that ]\Ir. Carter has not appreciated the grounds on which Orbitoides and Orbitolites are placed,
according to the plan of classification jointly adopted by ^Messrs. Parker, Rupert Jones, and myself, in
two different primary divisions of Forarainifera.

304 FAMILY NUMMULINIDA.

canal-system. Of all existing Foraminifera, Thioporus most approximates Orbifoides in the
structure of its superficial laminae, as Cyclocli/peus does in that its median plane.

509. Geolopcal Distribution, — This genus seems to have made its first appearance in the
Maastricht Chalk, but to have been more fully developed in association with Nummulina in
most of the localities in which that type attained its extraordinary predominance at the com-
mencement of the Eocene period. Its smaller forms, chiefly belonging to the species
0. Fortisii, present themselves abundantly in the Nummulitic limestone of the Western
Pyrenees, in that of Northern Italy, and in that of the borders of the Black Sea ; the larger
and more developed examples of both species occur intermingled with Nummuhtes and
Orbitolites in Scinde and other parts of northern India ; but this tj^pe is found in the
greatest abundance in the American Continent, the so-called " Nummulite limestone " of
Alabama, which extends over an immense area in that state, being almost entirely made up
of the remains of 0. Mantelli. It occurs also in Madagascar, and is abundant in Jamaica,
where it is associated with Nummulites.

Genus VIII.— Fusulin.a. (Plate XII, figs .24—29).

510. History. — The genus Fiisulina was instituted in 1829, by Fischer de Waldheim
(■ Oryctograph. Moscou,' p. 126), for the reception of a group of fusiform Foraminifera
occurring in sreat abundance in the white Carboniferous Limestone of Russia. It was first
adopted by D'Orbigny, in his palaeontographical contribution to Sir R. Murchison's ' Geology
of Russia,' and was subsequently associated in his systematic treatises (lxxiii, lxxiv) with
Nonionina and Nujumulina, to which he stated it to correspond in its single median fissured
aperture, and in the absence of subdivision in its chambers, notwithstanding the close approxi-
mation which its form presents to that of Alveolina. By Prof. Ehrenberg, on the other hand,
the most elongated forms of Ftisiilina were described and figured (xlii) under the name of
Alveolina, whilst to the more globular forms he gave the name BoreJis, which he adopted
from Montfort (^ 146) ; though it is not a httle singular that among the specimens which he
figured are internal ' casts ' which very clearly indicate the Nummuline affinities of this
type. Messrs. Parker and Rupert Jones (lxxx a) have associated Alveolina and Fusvlina as
allied, if not identical generic forms ; but in so doing they have been misled, as I conceive,
by a resemblance which is certainly more striking than D'Orbigny recognised between the
plans of growth of these two types ; whilst they have not given what I consider to be
adequate value to the essentially Nummuline character of the aperture, which will be found
to harmonise with the best information I have been able to obtain respecting the texture of
the shell.

511. Eaiernal Characters. — The ordinary form of Fi(sulina, well expressed by its name,
bears a very close general resemblance to that of Alveolina (^ 147) ; and, as in that genus, we
find that it may, on the one hand, be elongated into a cylinder, or, on the other, be shortened
to a prolate spheroid. The F. hjperbona of Salter ('Belcher's Arctic Voyage,' 1855, vol. ii.

GENUS Fl SILINA. 305

p. 380), the Borrlis cou.'slrivld, Ehr., has been supposed to be differentiated by a constriction in
the middle of its length; but this is onlj' an occasional modification. When the shell can be
sufficiently freed from its matrix for the characters of its surface to be distinguished, this is seen
(Plate XII, fig. 27j to be marked out by ])arallel septal bands running in the direction of the
axis, into a succession of segments of nearly uniform breadth ; but these segments are not
crossed on the surface, as they arc in , /Ave////'/, by regular and distinct secondary furrows,
though there is sometimes an external indication of that subdivision of the principal chambers
which will be shown to exist in the interior. The form of the septal plane (fig. 27, <\ e) very
closely corresponds with that of Aheolinn, as it is comparatively narrow in the centre of its
length, and spreads out widely at its extremities ; but the nature of the aperture differs com-
pletely. For instead of a single or multiple series of pores extending along its entire
length, we here find only a single slit-like fissure (fig. 27, «) limited to its middle region ; the
limitation of the communication between the successive elongated segments, and between the
last of these segments and the exterior, thus contrasting very strongly with the freedom which
we have seen to prevail in the segmental communications of Alceolina, whilst it closely cor-
responds vrith that which is characteristic of the Nummuline series.

512. Interna/. S/nicfure. — In this, as in most other fossils of the Carboniferous Lime-
stone, the ultimate texture of the shell has been so far altered by molecular change as to
make it impossilile to speak with certainty as to its character. But in several of the sections
which I have made, I find an appearance (fig. 26) indicative of a porosity resembling that
of the Nummuline and Rotaline shells ; this appearance, so far as I can judge, having been
produced by closely set, parallel tubuli, intermediate in diameter between the fine tubuli
characteristic of the former group and the coarse pores usually seen in the latter. In the
very numerous sections which I have made of Alvcoliua and other porcellanous Foraminifera,
fossil as well as recent, I have never seen any appearance which at all corresponds to this ;
and I cannot but think it much more probable that it indicates a definite structure which has
been in great degree altered by molecular change, than suppose that the homogeneous
texture of a porcellanous shell has given place to one in which differentiation of some kind is
so distinctly marked. The general structure of the interior of the most developed forms of
this type will perhaps be best understood from the " cast" figured by Prof. Ehrenberg (xlii)
from one of its simpler forms ; for we see in this (fig. 24), an arrangement very like that which
the segments of a simple Nummuline shell would present if their alar prolongations were to
extend themselves on either side in a line with the body of each segment, instead of folding-in
towards each other as they do in discoidal shells. The difference between this and the
ordinary more complex type, of which sections are represented in figs. 25 — 29, consists essen-
tially in this, that in the latter each of the elongated alar prolongations is broken up into a
necklace-like series of sub-segments connected by a longitudinal stolon. In the transverse
section taken across the median portion of the shell, represented in fig. 25, we see the spiral
succession of the principal chambers, which are divided from each other by septa formed by
the inflection of the external wall ; these septa, which are composed of a single lamella, do not
reach the surface of the penultimate whorl, but leave a .fissured passage («), through which
the chambers communicate with each other (as is better seen at ", a, fig. 26), just as
in the ordinary shells of the Nummuline type. The same transverse sections show the

;J9

306 FAMILY NUMxMULINIDA

separation of the principal chambers from their lateral extensions by the transverse septa
{c, (■), which are perforated close to the external side of the chambers, by the large, round, or
oval apertures (i, li), for the passage of the longitudinal stolons. The alar extensions are
themselves subdivided by similar septa, so that when they are laid open longitudinally, as at
d, fig. 27, we see a succession of rounded chamberlets, connected by a continuous gallery, as
is shown on a larger scale in fig. 27, li, V . The chamberlets of successive chambers alternate
with one another in position, as seen at d, fig. 27, and on a larger scale in fig. 28 ; and hence
arises a peculiar appearance presented by sections, by which at first 1 was considerably per-
plexed. In fig. 29 it will be seen that whilst at b, 1, the stolon-passages open into the
cavities of the chamberlets, they seem at U , V to lie between lamellae of the septa, which
separate to give them passage ; but it becomes obvious, from a comparison of this figure with
fig. 28, that whilst a section across the line a a , will traverse the open cavity {(■) of the cham-
berlets of one row, it will traverse the narrow gallery {!/) between the aUernating chamberlets
of the next row ; and thus the apparent lamellse are really two distinct septa, which here
close together around the connecting stolon, but which presently separate again to form a
chamberlet. The alar prolongations widen out greatly towards their extremities ; and their
secondary septa (as shown at fig. 27, ./'.,/■), instead of crossing them transversely to the axis of
the shell, come to lie very obliquely to it, giving rise to a variation which is at first very
perplexing in the appearances presented by sections dividing this part of the shell either
transversely or longitudinally. The appearance of divarication between two septal lamellae,
for the purpose of giving passage to the longitudinal stolons, is here such (fig. 29, 0', //') as very
strongly to suggest the idea of a canal-system ; but I am satisfied that this appearance is to
be explained by the alternation already described as existing between the chamberlets of one
row and those of the next ; so that if we could trace onwards any one of these passages, it
would be found immediately to open-out into a chamberlet. I have not been able to discover
in this type any real indication of the existence of a canal-s}^stem.

Affinities. — It is not without hesitation that I have assigned to this type the position in
which I have here placed it ; Messrs. Parker and Rupert Jones having strongly expressed
themselves (lxxx a), in favour of its intimate relationship to AJveoliiia. The balance of
evidence, however, appears to me decidedly in favour of its Nummidine character ; for although
the tubularity of the shell cannot be certainly afiirmed, yet it is verj^ strongly indicated ; and
its indications arc confirmed by the Nummuline character of the aperture, as well as by the
very close conformity to the general structure of the Nummuline type, which is admitted by
Messrs. Parker and Rupert Jones themselves to be presented by the simpler forms oi FusuJIua.
It appears to me, therefore, that the relation of Fit-mUm to Alveolina is one of ' isomorphism'
only, each type representing the other in its own series ; and thus a very interesting
parallelism is completed between the four principal plans of conformation which are presented
by the higher types of the Porcellanous and the Vitreous series respectively :

Porcellani'u . V'tlrea.

Simple complanate spiral Pcneroplis. Opeiculiiia.

Spiral, with the chambers subdivided into chamberlets . . Orbiculina. Heterostegina,

Cyclical, with annuli subdivided into chamberlets . . Orbitolites. Cycloclypeus.

Spiral with elongated axis, chambers subdivided into chamberlets Alveolina. Fusuhna.

GE^VS FUSULINA. 307

The apparent absence of a canal-systcni, and the ostensible singleness of the septal lamellae,
may be due to the molecular change to which the shell has been subjected; but even
admitting them to be real, they do not negative the title of F/mi/hx/ to a place in the Num-
nuiline series, since, as we have seen, the same characters of degradation arc presented by

Geolofjicol Distrihutum. — This type is not known to present itself in any other formation
than the Carboniferous Limestone, occurring especially in that of Russia, a particular bed of
which is in great prat made up of vast accumulations of its fossilized shells ; it occurs also in
the same formation in the State of Ohio (North America, civ), and in the Arctic regions.

APPENDIX

The following Tabic exiiibits the names assigned by Messr.s. Parker and Rupert Jones to tlic speeies
and varieties described and figured in Professor Williamson's ' ^Monograph on the Recent Foraminiferu
of Great Britain.' This nomenclature is founded on the principles set forth by those authors in their
successive memoirs "On the Nomenclature of the Foraminifera" in the 'Annals of Natural Historv,' and
adopted, with some modifications, in the present work. Their rule has been to retain the qjccijic names
assigned by the systematist by whom the type was first properly designated. Hence some of the names
ol' types and varieties which liavc since been differently designated, are those assigned by D'Orbigny in
his first memoir ('Ann. des Sci. Nat.,' torn, vii) to the forms delineated by Soldani, whose figiu'cs have
been carefidly collated. Another reason why some altered names appear, is because Messrs. Parker and
Rupert Jones have been led by the wider range of their studies to adopt in several instances a different
style of type from tliat furnished by the simple forms of the British Fauna surveyed by Professor
Williamson; their aim having been to adopt those forms iis types of speeies, which give a fair repre-
sentation of all or neai'ly all the characters that seem properly to belong to each.

Plate. Fig. Names uscJ in Pinf. 'W^illiamson's Jlonograph.
1. 1. Proteonina fusiformis

Names now proposed.

Single joint (last) of Lituola nautiloidea, Lu-
mdrck, var. scorpiurus, Montfort.

2,3.

— pseudospiralis .

Lituola nautiloidea. Lam. (Feeble form.)

4.

Orlmlina universa ....

Orbulina universa, D' Orb.

5.

c.

Lagena vulgaris ....

— — var. cla\'ata

— — ,, perlucida .

Lagena hcvis, Mun-
taiju.

s.

— — » — • •

L. semistriata, W'll-

9.

— — ,, semistriata

Uamson.

10.

— — ,, striata

L. sulcata, IVulkcr and

11.

— — „ interrupta

Jacoli.

12, 13.

14.

— — „ gracilis . . -^

— — ,, substriata .

; L. striata, Montar/ii.

15, IG.

17.

18.

Entosolenia globosa ....

— — var. lineata.

— costata ....

L. globosa, Moidai/i'.
L. eaudata, D' Orhiijiiij.
L. sulcata. W. and J.

Type, Lagena sulcata,
IFuUcer cV Jacob.

19—21.

— marginata

22, 23.

24..

— — var. lucida

— — „ oruata .

L. mar;;iiKita, lilijji-

25, 26.

27, 28.

— — ,, lagenoides

— — „ quadrata . ,

29.
30.

— ■ squamosa

— — var. scalariformis

L. squamu.-,n. Man-
ia r/u.

31.

— — „ catenulata

L. melo, D'Orlj.

32,

— — „ hexagona

L. ^r[nvimosa. M on! a (/a.

310

APPENDIX.

PiuATE. Fig. Names used in Prof. A\'i!Iiainson's JIono2rai>l
II. 33 — 35. Linsrulina carinata .

30 — 38. Nodosaria radicula .

39. — pyrula

■10, 41. Dentaliiia subarcuata

42. — —

43, 44. — —

var. jugosa

45. — legumcii .

4(5 — 49. — — var. linearis

.OO. Frondicularia spatliulata .

51. — Arcliiaciana.

52, 53. CristeUaria calcar

54.
55.

56—59.
60, 61.
(52.

63.
64—67.

III. G8, 69. Nonionina Barleeana

70, 71. — umbilicatula

72, 73. — Jeffreys! .

74, 75. — elegans

76, 77. Nummulina planulata

— oar. rotifer

— „ oblonga
subarcuatula

— var. scapha

Names uow proposed.

Liuguliua carinata,
D'Orb.

Nodosaria lougicauda.

Type, Nodosaria ra-
phaiins, TAnn.

D'Orb.
N. pyrula, D'Orb.
Dcutaliua communis,

D'Orb.
D. aeicula, Lamarck.
Nodosaria rapbanus,

Linn.
Vaginulina linearis,

Montaffu.
Fi'ondicularia compla-

iiata, Defrance.
F. Archiaciana. D' Orb.
CristeUaria rotulata,
Lamarck. .
\ C. crepidula, Fichtel
i and Moll.

C. Italica, Defrance.
,, elongata Margiuulina lituus,

D'Orb.
„ costata . ^I- laphanus, WOrb.
„ — . Planularia strigilata,
Reuss.
Nonionina umbiiica-
tula, Mont. (Var.
of N. asterizans,
Fichtel and Moll. )
N. depressula, Walker
and Jacob. [Var.
of N. asterizans,
F. and M.)
Litnola Cauaricnsis, Z)'Ori. (F«r. ofL. nauti-

loidea, Lamarck.)
Operculina ammonoides, G ronovins. ( Var. of

Nummulina planulata. Lam.)
Nummulina planulata, Lamarck, var. radiata,

Fichtel and Moll.
Polystoniella crispa, Linn.

^ Type, PolystomcUa
crispa, Liim. sp.

78 — 80. PolystomeUa crispa .

81, 82. — umbilieatula . . . i

j^o^. _ _ j.^,,. inco-la. J ^' '^''^^P'^' ^''"'■' ''"'■• striato-punetata, 7''. ^V^^^-

83—85. Pencroplis plauatus .... Peneroplis planatus, F. and M.

86— 89. Patellina corrugata . . . . Patcllina corrugata, rF5//i«w«o«. (r«r. of P.

concava, Laniarc/c.)
IV. 90—92. llotaliua Beccarii .... Rotalia Bcccarii, Linn.

93,94. — iuflata .... TrocLammina inflata, Montagu. [Var. of T,

squamata, Parker and Jones.)

APPENDIX.

.311

Ti-ah. Fig. Names used ia Prof. Williamson's Rlonojifraph.
9.") — 97. Tvotaliiia turgida

98—100. — oblonga ....

101—10.3.
101, 105.
106—108.
109—111.
112.
V. 113.

Ill, 115.

— concamerata

— — Yoini

— nitida

— mamilla

— ochracca

— fiwi-ii

116 — 118. Globigcrina Liilloides
119,120. Plauorbulma vulgaris

121—123. Ti-imcatuliiia lobatula

124, 125. Bulimiiia piipoicle.-^

126, 137. — — var. marginata

128. — — „ spinulosa

129, 130. — — „ fusiformis
131. — — „ comprcssa

132, 133.
134, 135.
136, 137.

convoluta

elqgantissima
areuacca

138, 139. Uvigerina pygnifea .
140. — angulosa

VI. 141, 142. Cassiduliua la;\dgata
143, 1 11. — obtusa

145. Polymorpbina lactea

IIG,

147.

148.

119.

150.

151,

1.52.

153-

-155

156,

157.

158,

159.

100,

161.

162,

163.

161,

165.

160,

167.

— rar. acuminata

— „ oblonga

— „ fistulosa

— , , concava

— ,, communis
myristiformis

variabilis

Names now proposed.

Nouiouiua astcrizans, F. iy; M., vur. turgida,
Williamson. (Typo, I'olystouiclla crispa,
Linn.)

Pulviaulina auricula, F. tuid M. [far. of P.
rcpanda, F. arid M.)

Pulviuulina rcpauda, F. and M.

Discorbina turbo, D' Orb., var. globularis, D'Orh.

llotalia Ecccarii, L'liiii., var. nitida, IVilUamsoii.

Discorbuia tiu'bo, D'Orh., vur. rosacea, D'Orh.

Discorbina turbo, luir. ocliracca, U'illiamsoii.

Valviilina triangularis, D'Orh., vur. Austriaca,

D'Orh.
Globigcrina biilloidcs, D'Orh.
Planorbulina I'arcta, F. and M., vur. Medi-

tcrraucnsis, D'Orh.
Truucatnlina lobatula, IV. and J. [Var. of

Planorbulina farcta, F. and M.)
Bulimina Prcsli, Reiiss, var. pupoides, D'Orh.
B. Presli, Reuss, var. marginata, D'Orh.
15. Presli, Reuss, var. aculcata, D'Orh.
B. Prcsli, Reuss, var. ovata, D'Orh.
Virgulina Sclireibersii, Czjeck. (Type, Bulimina

Presli, Reuss.)
B. Prcsli, Reuss, var. convoluta, Williamson.

B. Presli, Reuss, var. elegantissima, D'Orh.
Verneuiliua polystropha, Reuss. (Type, Tex-

tularia agglutinans, D'Orh.)
Uvigerina pygmaja, D'Orh.
U. pygmaia, D'Orh., var. angulosa, Williamson.
Cassididina laevigata, D'Orh.

C. IsEvigata, var. erassa, D'Orh.
Polymorpliina lactea, IV. and J., var. com-
prcssa, D'Orh.

P. lactea. Walker and Jacuh.

I P. lactea, r:arieties.

I

vur. coniea

var. spathnlata
„ difformis .

P. lactea, var. tubulosa, D'Orh.
P. lactea, varieties.

Tcxtularia sagittula, Defrance. (Type, T. agglu-
tinans, D'Orh.)

T. troclms, Z)'Oci. (Type, T. agglutinans, C'Or/i.)

T. agglutinans, D'Orh., rar. variabilis, Wil-
liamson.

T. agglutinans, D'Orh., var. pygmaia, D'Orh.

T. agglutinans, D'Orb., var. difformis, D'Orh.

312

APPENDIX.

Plate. Fig. Names used in Prof. Williamson's .Monograph.

168. Textularia variabilis rar. lievigata •

169 — 171. Biloculina ringens

172 — 171. — — rar. cariiiata

175, 176. — — „ Patagonica. .

177. Spiroloculina depressa

178. — — rnr. rotundata.

179. — — „ Cymbium
180—182. Miliolina trigonula ....

183-185.
186, 187.

188, 189.

190—194.

195.

196.

197, 198.
199—201.
202.
203.

20 1.

— scminulum

— — rnr. oblonga

disciformis

biconiis

I'ar. elegans
„ .ingulata

Vertebralina striata
Spirillina foliacea .
Spirillina perforata .

— arenacea .

— margaritifeni

Type, Miliola scmi-
uuhim, Linn.

Names now proposed.
T. agglutinaus, D^Orb., vur. variabilis, U'il/iam-

A'Offl.

^liliola seminidum, Linn., rar. ringens. Lam.

Bdoculma compressa, ""
D'Orb.

B. elongata, D'Orb.

Spiroloculina limbata,
D'Orb.

Sp. complanata, La-
marck.

Spiroloc. canaliculata,
D'Orb.

Triloculina trigonida,
Lamarck.

Miliola seminulum, Linn.

Tiiloculina oblonga,
Montagu.

Quinqueloculina se-
cans, D'Orb.

Quinqueloculina bi-
coniis, IV. and J.

Triloculina Brongni-
artii, D'Orb.

Quinqueloculina Fe-
russacii, D'Orb. ,

Vertebralina striata, D'Orb.

Cornuspira foliacea, PhiUipjn.

Spirillina vivipara, Ehrenb.

Trochammiua sqnaruata, P. and J., rar. inccrta,
D'Orb.

Spirillina vivipara, Ehrenb., var. margaritifera,
Williamson.

Type, Miliola semi-
nulum, Linn.

C'OKRKiEXDA.

I'aye 17, lines 15 and 20, .ir^d jiagc 2J, lini' 11, I'm- IIexicclosa read Eeticuiahia.

Page 18, itoie. The autlior lias been informed by Prof. KiiUiker that he did not employ the term " nucleus " in its technical
signification, but that by the terms "cortical" and "nuclear" substance he meant only what is described in the text as "ectosarc"
and ** endosarc."

Page 53, line 20, the words " the duplication of the septal jiartitions " to be omitted ; the author having found since
writing them that this structm-al feature is limited to the higher types of the hyaline Foraminifera, instead of being comnmn (as he at
first believed) to the whole series.

Page 105, last five lines. In here stating Cyclolina to he a variety of OrbitoUles, the author was misled by Mr. Carter, who
had described under the name Cyclolina a fossil which (as he has since discovered, p. 230, «ofc) does not really accord with
D'Orbigny's type of that genus. Mr. Carter's Cyclolina is a true Orbitolites, as stated in •; 186 ; but D'Orbigny's Cyclolina is
probably a Fatellina (p. 233). Further, of the forms to which D'Orbigny's designation Orbitolina has been applied, a ))art seems
referable to the genus Tinoponis, and another part to Fatellina, as explained in the account of those genera.

Page 174, line 7, for " Exallostegues " read " E.NTOMOSTiiGUES."

Page 191, line 8 from bottom, for " Bigerina" read " Sigenerina."

Page 198, line 5, for " plan " read " plane."

Page 201, line 2 of explanation of Fig. XXXII, for " Montague " read " Montfort."

Page 202, line 1 of T 347, for "genus" read "group."

Page 207, line 7 of f 359, for " 20 " read ^' 201."

Page 215, line 1, for "it is neither abundant nor of more than half its cn-dinary size," i-ead "althongh abundant, it is npt of
more than half its ordinary size."

Page 229, line 1 of f 402, for " Geographical" read "Geological."

Page 232, line 1 of explanation of Fig. XXXVII, for " hntiailaris " read '■ <

INDEX.

Acunfhometra, 21

ACANTHOMETRINA, family, 21

Acervulina (Sell.), 209

Acervuline mode of growth, 55

Aciciduria, geaus, 137-139 ; its history, 137; external
characters, 13"; internal structure, 138 ; affini-
ties, 138; geological distribution, 139

Actinophys, genus, 15 ; its structure and actions,
18-20 ; reproduction, 34-30

AcTixoPHRYXA, family, 18-21 ; reproduction of, 34-37

Adelosina (D'Orb.), 75

Agathistfegues (D'Orb.), 5, 75

Alar prolongations of chambers, 58,59 ; inNummulina,
270, 271

Alveolina, genus, 99-104; its history, 99; external
cliaracters, 99; internal structure, 100; simple
type, 100; complex type, 101; casts, 102; va-
rietal forms, 103; affinities, 104; geographical
and geological distribution, 104

Alveolina Coscii, 103

— elongata, 103

— melo, 103

— ovoidea, 103

— Quoii, 99

— rotella, 103

^OTOsia, genus, 15; its structure and actions, 23-26;

reproduction, 33 ; encysting process, 34 ; sexual

generation, 35-30
Amoeba bilimbosa, 23, 24, 20

— limax, 25

— porrecta, 24

— princeps, 24

— quadrilineata, 25

— radiosa, 24

Amoeba verrucosa, 36, 39

Amiebixa, family, 26-28 ; reproduction of, 35-30.

AmpMstegina, genus, 241,247; its history, 241 ; ex-
ternal characters, 242, 243 ; internal structure,
243-245 ; casts, 245, 240 ; varietal forms, 246 ;
affinities, 246 ; geographical and geological distri-
bution, 247

Amphistegina Cumingii (Carp.) 241, 275.

Anomalina (D'Orb.), 200, 207, 208

— coronata, 208

— punctulata, 201

Aperture, septal, relative dimensions of, 51, 52; value

of as differential character, 55
Arcella, genus, 27

Arenaceous shells of Foraminifera, 46, 47, 54, 140
Articulina (D'Orb.), 73, 75
Assiline forms of Nummulina, 204, 207, 270
Asterigerina (D'Orb.), 200, 213
• — • earinata, 213

— lobata, 213

— vulgaris, 213
Asterigerine flaps of Rotalines, 202, 204
Astral lobes of Amphistegina, 245

B.

Bigeuerina (D'Orb.), 190, 191

Biloculina (D'Orb.), 75, 78

Bolivina (D'Orb.), 194, 190

Borelis (Moutf.), 99, 304

Borelis constricta (Ehr.), 305

BuHmina, genus, 194-197; its history, 194; external
characters and internal structure, 194-196 ; varietal
forms, 190 ; affinities, 196 ; geographical and geo-
logical distribution, 197

40

314

INDEX.

Kulimina arei)a<-ea (Will.), 102

— convoluta, 195

— costata, 196

— elegantissima, 195, 190

— marginata, 195, 196

— pupoidcs, 195, 190

— pynila, 195

C.

Calcarini,, genus, 216-22:', ; its history, 199,200; ex-
ternal characters, 210-219 ; internal structure,
219-222; canal system, 221 ; irregularities, 222 ;
varietal forms, 217, 218, 223; affinities, 223;
geological and geographical distribution, 223

Calcarina calcar, 223

— pulchella (D'Orb.), 213

— Spengleri, 210

Canal-system of Foramiuifcra, 50, 51 ; of Calcarina,
221 ; of Carpenteria, 18S ; of Cycloclypeus,
295,290; of Heterostegiua, 291 ; of Nnramulina,
272, 273 ; of Operculiiia, 25S-200 ; of Orbitoides,
302; of Polystomella, 213-215 ; of Rotalia, 214

Candeina (U'Oi-b.), 190-192

Carpenteriii, genus, 186-189; its history, 180; ex-
ternal characters, ISO ; internal structure, 187-
189; spougeous nature of animal, 188, 189 ; affi-
nities, 189; geographical and geological distribu-
tion, 189

Cassidulina, genus, 190, 198; its history, 197; cx-

tei-nal characters and internal structure, 197, 198;
affinities, 1 98 ; geographical and geological distri-
bution, 198

Casts, internal, of Foraminifera, 10; of Alveoliua, 102;
of Amphistegina, '245, 246; of Orbitoides, 300;
of Polystomella, 280, 283

Ceriopora cribrosa (Goldf.), 189

Chrysalidind, genus, 183; history, 193; external cha-
racters and internal structure, 193; geographical
and geological distribution, 193

Chrysaora damtecornis (Lamour.), 189

Classification, of Foraminifera, 40-02 ; of Rhizopoda,
12-17

Clavuhna (D'Orb.), 147, 192

Clavuline forms of Valvulina, 147 ; of Yerneniline
Textularia, 192

Coccoliths, 47

Coeccspheres, 47

Collospha;ra Huxleyi (Miill.), 23

Conulites (Carter), 229, 233

Cornuspira, genus, 68, 09 ; history, 68 ; external cha-
racters, 08; internal structure, 08,09; affinities,
C9 ; geographical distribution, 09 ; geological
distribution, 09

Cornuspira foliacea, 08

— perforata (Sch.), 68

— planorbis (Sch.), 08
Coscinospira (Ehr.), 84

Cristellaria, sub-genus, 159-100; its external charac-
ters, 162; internal structure, 102, 103; varietal
forms, 163; affinities, 165; geographical and
geological distribution, 105

Cristellaria calcar, 102

subarcuatula, 163

Cruciloculina (D'Orb.), 75, 80

CuneoUna, genus, 193, 194 ; its history, 193; external
characters, 193; internal structure, 194 ; affinities,
194 ; geological distribution, 193

Cycloclypeus, genus, 292-298 ; its history, 292 ; exter-
nal characters, 292 ; internal structure, 293-296 ;
canal-system, 295, 296; monstrosities, 296;
affinities, 290, 297 ; geographical and geological
distribution, 297

Cyclohna, of D'Orhigny, 229; of Carter, 120, 230

Cyclolina cretacea (D'Orb.), 233, 235

Cyclost^gues (D'Orb.), 5, 7, 105, 240

Cymhalopora, genus, 200, 215, 216; its history, 215;
external characters and internal structure, 215,
216 ; affinities, 210 ; geographical and geological
distribution, 210

Cymbalopora bulloides, 210
— Foeyi, 215

D.

Dffc/y/o/jorff, genus, 127-137; its history 127; external
characters and internal structure, 127-136; affini-
ties 130; geographical and geological distribution,
137.

Dactylopora auuuhis, 129

— clypeina, 131

— cylindracea, 132
— - digitata, 130

— cruca, 128

— glandulosa, 132

— reticulata, 131
Dendritina (D'Orb.), 84, 88-91.
Dentaliua (D'Orb.), 100, 103
Dictyosoma, 22

Difflmjia, 27

Diraorphina (D'Orb.), 103

BiscorUaa, genus, 200, 203-200 ; its history: 200 ;
external characters and internal structure, 203, 204 ;
varietal modifications, 205 ; affinities, 205 ; geo-
graphical and geological distribution, 295

Discorbina biconcava, 201

— dimidiata, 201

— GerviUii, 204

INDEX.

315

Discorbina globularis, 204

— iiiamilla, 205

— rimosa, 20")

— rosacea, 20.")

— trocbidiformis, 20 I, 205

— turbo, 20 1

— vesicularis, 204, 205

Distribution, Geograpbical and Geological, of Aciculaiia,
139; of Alveolina, 104; of Ampliistegina, 217;
of Bulimina, 197; of Calcariua, 223; of Carpen-
teria, 189; of CassiduHua, 198; of Cbrysadiliiia,
193; of Cornuspira, C9 ; of Cristellaria, 1C5 ; of
Cuneolina, 193 ; of Cycloclypeus, 297 ; of Cym-
balopora, 210; of Daotylopora, 137; of Discor-
bina, 205; ofFabidaria, 84; of Fusuliua, 307 ; of
Globigerina, 183; of Heterostegina, 292; of
Lagena, 159; of Lituola, 145; of Miliola, 92; of
Nodosarina, 105 ; of Nubecularia, 72 ; of Nummu-
lina, 275 ; of Operculina, 2G2 ; of Orbiculina, 98 ;
of Orbitoides ; 303; of Orbitolites, 120; of Orbu-
lina, 178; of Ortboccrina, 166; of Ovulites, 180;
of Patellina, 255 ; of Planorbulina, 209; of Poly-
morpbina, 169; of Polystomella, 287; of Poly-
treraa, 237; of Pullcnia, 184 ; of Pulvinulina, 21 1 ;
of Kotalincc, 214 ; of Spbxroidina, 185 ; of Spiril-
liua; 181 ; of Textiilavia, 192 ; of Tinoporus, 229 ;
of Trochammina, 142; of U vigerinn, 170; ofVal-
Tulina, 148; of Vertcbralina, 74
D'Orbigny's classification of Foraminifcra, 5-7
Dujardin's designation of Rbizopod type, 7 ; bis classi-
fication, 61, 62

E.

Ectosarc, differentiation of, 18

Ebrenberg, Prof., his classification of Foraminifcra, 8

Ebrenbergina (Eciiss), 198

Enallostegues (D'Orb.), 5, 171

Endosarc, differentiation of, 18

Entomostegues (D'Orb.), 5, 171, 240

Entosolenia (Ehr.), 157

Euplypha, 21 ; reproduction of, ;16

F.

Fabularia, genus, 75, 82-84 ; its bistor}', 82 ; external
characters, 83 ; internal structure, S3 ; affinities,
83 ; geological distribution, 84

Faujasina of Williamson, 213

Fanjasina carinata (D'Orb.), 2SC

Flabellina (D'Orb.), 160, 161

FORAMINIFERA, first constituted as a group by
D'Orbigny, 5 ; nature of first truly determined bv
Dujardin, 7 ; structure of first minutely studied by
Williamson, 9 ; relations of to other I!hizopods,
10 ; characters and actions of animal of, 28-32 ;
reproduction of, 33, 37-39 ; general principles of
classification of, 40-62 ; relation of nionotbalamous
and polytbalamous forms of, 41, 49; texture of
shell of, 44-48 ; mode of increase of shell of, 48-50;
intermediate skeleton of, 50-53 ; canal-system of
50-53; isomorphism among, 53, 54; relative value
of ch.aracters in, 54-56 ; mode of grouping into
genera, 56 ; instability of specific distinctions in,
56-61 ; primary subdivisions of, 61, 62

Frondicularia (D'Orb.), 160, 164

Frumentaria (Sold.), 74

Fwrnlina, genns, 304-307 ; its history, 304 ; external
characters, 304 ; internal strnctiire 305 ; affinities,
306; geological distribution, 307

G.

Gaudryina (D'Orb.), 190, 191

Gemmulina (D'Orb.), 190, 191

Genera, value of, iu Foraminifcra, 56

Geographical Distribution of Foraminifcra, see Distri-
bution

Geological Distribution of Foraminifcra, see Distribution

Gcoponus stella-borealis (Ehr.), 28i)

Glandulina (D'Orb.), 160

(llobir/erina, genus, 181-184; its history, 181 ; external
characters and internal structure, 181, 182; affini-
ties, 182, 183; relation to Orbidina, 177, 178;
geographical and geological distribution. 183, 181

Globigerina bilobata, 177

— bulloides, 181

— hellcina, 181

— hirsuta, 181

— inflata, 183
Globioekin.e, sub-family, 173-175
Globigerinid.v, family, 171-175 '
Globulina (D'Orb.), 167
Grammostomum (Ehr.), 190, 192

Gromia, genus, 64 ; animal of, 29 ; reproduction of, 39
Gkomida, family, 63
Guttiilina (D'Orb.), 167

H.

llauerina, sub-genus, 81
Ilauerina compressa (D'Orb.), 81

316

INDEX.

Helicostfegues (D'Orb.), 5, 171, 240

Heterostegina, genus, 288-292 ; its history, 288 ; ex-
ternal characters, 288 ; internal structure, 289-
291; affinities, 291; geographical and geological
distribution, 292

Ilymenocjclus (Bronn), 298

Hyaline texture of shell of Foraminifera, 45, 46

I.

Impeeforata, Sub-order, Gl, C2.

Intermediate skeleton 50-52 (see Supplemental Skeleton)

Isomorphism of Foraminifera, 53, 54

L.

ia^eMff, genus, 15C-1 59 ; its history, 156-159 ; external
characters and internal structure, 157, 158; mons-
trosities, 158; affinities, 158; geographical and
geological distribution, 159

Lagenida, family, 150, 154-156

Lagynis, genus, 65 ; encysting process in, 34

Larvaria reticulata (Defrance), 132

Lieherkuhnid, genus, 63 ; animal of, 28, 29

Lingulina (D'Orb.), 163
— mutabilis, 164

Lituola, genus, 143-145; its history, 143; external
characters and internal structure, 143, 144;
affinities, 145 ; geographical and geological dis-
tribution, 145

LiTUOLiDA, family, 140

LoBOSA, Order, 16, 23

Lycophris dispansus (Sow.), 299

Lycophris ephippium (Sow.), 299

M.

JIarginal Cord, of Xummulina, 269, 270 ; of Operculiua,
257, 258

MarginuHn^ (D'Orb.), IGO, 163

2Iiliola, genus, 74-82; its history, 74, 75; external
characters and internal structure, 75-81 ; varietal
forms, 77-81 ; affinities, 81 ; geographical and
geological distribution, 82 ; reproduction, 37

ililola cyelostoma, 79
— saxorum, 80

iliLioLiDA, family, 66

Miliolina (Will.), 75

jMiliolites (Lam.), 74, 75

Millepora rubra (Lam.), 235

Monostfegues (D'Orb.), 5

Jlouothalamous Foraminifera, 41, 42, 49, 139
Jlonstrosities of Lagenida, 39, 158; of Orbitolites,

123; of Cycloclypeus, 296
Multilocular Foraminifera, 41, 42, 49

N.

Nodosaria, sub-genus, 161; its varietal forms, 163,

164
Nodosarina, genus, 159-166; its history, 159, 160;

external characters, internal structure, and varietal

form.s, 161,165; affinities, 165; geographical aud

geological distribution, 165
Nonionina, sub-genus, 286
Nonionina asterizans, 286

— buUoides (D'Orb.), 184

— elegans (Will.), 252

— faba, 286

— limba, 286

— sphfcroides (D'Orb.), 184

— stellifera, 286

— striato-punctata, 286

Nuhecularia, genus, 69-72 ; its history, 69 ; external
characters, 69, 70; internal structure 70 ; varietal
forms, 7 1 ; affinities, 72 ; geographical and geologi-
cal distribution, 72

Nummiilina, genus, 262-276 ; its history, 262-266 ;
external characters, 266-268 ; internal structure,
268-273 ; alar prolongations of chambers, 270-271 ;
canal-system, 272, 273 ; varieties, 273 ; affinities,
274 ; geographical distribution, 275 ; geological
distribution, 276

Nummulina Biaritzensis, 271

— complanata, 271

— Cumingii, 266, 275

— distans, 269

— Garensensis, 271

— Gyzehensis, 269

— laevigata, 265, 271

— Leymerii, 271

— obtusa, 266

— perforata, 266, 272

— planulata, 267, 275

— striata, 271

— variolaria, 275

— Verneuili, 271
NU5IMULINIDA, family, 238-241
Nummulites, see Nummulina

0.

Opercidina, genus, 247-262; its history, 217, 248;
external characters, 248-252; internal structure,
252-260; marginal cord, 257, 258 ; canal-system.

INDEX.

317

25S-2G0; reparalion after injuries, '_'fiO ; affinities,
2G1 ; geograpliical aiul geological distriljution, 202

Operculina incerta (D'Orb.^, 141

OrhiaiUnn, genus, !)3-0!l ; its liistory, 03 ; external
characters, 94, !)j ; internal structure, !).")-!)/ ; affi-
nities, 98 ; geographical and geological distribu-
tion, 98

Orbiculiua adunca, 93

— angulata, 93

— Malabarica, 97

— orbiculus, 93

Orlitoides, genus, 298-304 ; its history, 298 ; external
characters, 298, 299 ; internal structure, 299-302 ;
casts of, 300 ; canal-system of, 302 ; affinities, 303 ;
geological distribution, 304

Orbitoidcs dispansus, 298

— cphippium, 298

— Fortisii, 300

— Mantelli, 298, 300

— Prattii, 298
Orbitohna, genus of Lamarck, 224

— coucava (Lam.), 231

— conica (D'Arch.), 231

— gigantea (D'Orb.), 228

— lenticularis (Blnm.), 231

— vcsicularis (P. & J.), 224

OrbifoUtes, g&nns,, 105-12G; its history, 105; external
characters, lOG; simple type, external characters,
107; internal structure, 107-110; animal, 110-
112 : — co»ipte.c type, external characters, 112-114;
internal structure, 114-118; animal, 115, IIC;
reparation of injuries, 118-120; varieties, 120-
123; monstrosities, 123 ; affinities, 124-12G; geo-
graphical and geological distribution, 12G; re-
production, 37, 38

OibitoUtcs, macropora, 107

— Jlalabarica (Cart.), 97

— marginalis, 107

OrLulina, genus, 176-178; its history, 17(); external
characters and internal structure ; 170, 177; sup-
posed relation to Globigeriua, 177, 178; affinities,
1/8 ; geographical and geological distribution,
178 ; formation of ova, 39

Orders of Rhizopoda, 15-17

Ortkocerina, genus, IGIJ; its history, ICG; external
characters and internal structure, ICG; affinities,
ICG ; geographical and geological distribution, IGC

Ova, supposed, of Foraminifera, 3G, 39

Ovttlites, genus, 179; its history, 179; external cha-
racters and internal structure, 179 ; affinities,
179; geological distribution, 180

Ovulites clongata (Lam.), 179

— niargaritula (Lam.), 178

P.

Pamphagus mutabilis (Bailey), 28

Patellina, genus, 229-235 ; its history, 229 ; external
characters and internal structure, 230-234 ; affi-
nities, 234 ; geographical and geological distribu-
tion, 235

Patellina concava, 231

— Cooki, 233

— corrugata, 230

PeneropUs, genus, 84-93 ; its history, 84 ; external
characters, 84-80 ; internal structure, 8G ; varieties,
87-91; dendritine form, 88, 91; spiroline form,
88, 89 ; affinities, 91 ; geographical and geologi-
cal distribution, 92

Perfok.\t.\, sub-order, Gl, 149

Perforated shells of Foraminifera, 45, 4G

Placentula pulvinata (Lam.), 210

Plaffiopknjs, 20

Placopsilina cenomana (D'Orb.), 143

Plan of growth, value of as differential character, 48-55

Plamrbulina, genus, 200, 2UG-209 ; its history, 199,
200 ; external characters and internal structure,
20C, 207; truneatuliue form, 207; varieties, 208,
209 ; affinities, 209 ; geographical and geological
distribution, 209

Planorbulina farcta, 206

— meditcrranensis, 206

— retinaculata, 209

— vulgaris, 208, 209
Planularia (Defr.), ICO
Planulina (D'Orb.), 200, 207
Podostoma, 25, 26
PoLYCYSTix.i, family, 21

Pohjmorpltina, genus, 1G6-1G9; its history, 106-16/ ;
external characters and internal structure, 1G7,
168; affinities, 168, 169; geograpliical and geo-
logical distribution, 169

Polyniorpliina lactea, 1G7

— myristiformis, 1C7
Polymorphism of Foraminifera, 54, 55
Fulystomella, genus, 27C-288 ; its history, 276 : —

P. crispa, external characters, 278 ; internal struc-
ture, 278, 279 : — P. cratkulata, external cha-
racters, 279, 280 ; internal structure, 280-285 ;
casts, 280, 283 ; canal-system, 283-285 ; relation
to P. crispa, 285, 2S6 ; nonionine sub-genus,
286 ; affinities, 287 ; geographical and geological
distribution, 287, 288
Polystomella gibba, 286

— niacella, 286

318

INDEX.

Polystomella strigillata, Til

Polytlialamous Foraminifera, 4!, 42, 4P, 139,

Polytrema, genus, 235-237 ; its Listor3', 23.') ; external
characters, 235, 230 ; internal structure, 23fi ; affi-
nities, 23G, 237 ; geograpliical distribution, 237

Polytrypc cylindracea (Defr.), 133

Porcellanous shells of Foraminifera, 44, 45

Prattia glandulosa (D'Arch.), 132

Protozoa, sub-kingdom, 12

PseudocMtimys, 27

Pseudopodia, 13; of Kadiolaria, 15; of Lobosa. 16;
of Reticularia, 16

Pullenia, ^enus, 184; its history, 1S4; externa! cha-
racters and internal structure, 184; affinities, 184 ;
geographical and geological distribution, 185

PuUenia obliquiloculata, 183
— sphteroides, 184

Pulvinulina, genus, 200, 210, 211; its history, 200;
external characters and internal structure, 210;
varieties, 211; affinities, 211; geographical and
geological distribution, 211

Pulvinulina Badensis, 201

— caracolla, 210

— elegans, 21 1

— verniiculata, 211

Quinqueloculina, 75, 78

R.

Kadiolaria, 0-der, 15, 18-23

Renulina (Lam.), 74, 84

Renulites (Lam.), 74

Reparation of Injuries, in Orbitolites, 1 1 8- 1 20 ; in Oper-

culina, 260, 261
Reproduction of Rhizopoda, 32-39
Reticularia, Order, 17, 28-32; subdivision of, 61, 62
Rhabdogonium anomalum (Reuss), \6(}
RHIZOPODA, Class, first constituted by Dujardin, 7 ;

its organization and physiological characters, 12-

14; subdivision into orders 14-17: reproduction,,

32-39
Rimulina (D'Orb.), 160
Robertiua (D'Orb.), 195
Robuliiia (D'Orb.), 160

— arimiuensis, 162

— echinata, 162
Rosalina (D'Orb.), 200

— bulloides, 216

— Poeyi, 215

Rotalia, genus, 199, 201, 212,215; its history, 199-
201; external characters, 212, 213; internal

structure, 214; canal-system, 214 ; affinities, 214;
geographical and geological distribution, 215;
reproduction, 37, 38
Rotalia ammoniformis, 212

— Beccarii, 212

— elegans (D'Orb.), 210

— Gervillii, 204

— Menardii (D'Orb.), 210

— orbicularis, 213

— Partschiana (D'Orb.), 210

— pnlchella, 213

— repanda (D'Orb.), 210

— rosacea (D'Orb.), 205

— Schreibersii (D'Orb.), 210

— Scliroeteriana, 213

— Soldaui, 213

— turbo (D'Orb.), 204

— umbilicata, 213
Rotalina (Will.), 200

— iuflata (Will.), 141

— mamilla (Will.), 205

— nitida (Will.), 212

— oblongaCWill.), 210

— ocbracea (Will.), 205
Rotalin.e, sub-family, 174, 198-203
Rotalites trochidiformis (Lam.), 204

Sagrina pulcbella (D'Orb.), 169

Saracenaria (Defr.), 160

Sarcode, characters of, 1^

Sculpture of Shell, value of, 57-59

Segments, multiplication of, in Foraminifera, 4 1 ; con-
nection of, 51, 52

Septal aperture, relative dimensions of, 51,52; value
of as difi'erential character, 55

Septal plane, variations in form of, 57-59

Shell, intimate structure of in Foraminifera, 14, 48;
porcellanous, 44, 45 ; hyaline, or vitreous, 45, 46 ;
arenaceous, 47, 48

Sidcrolitcs (Lam.), 199, 223

Siphonia (Reuss), 200

Skeleton, value of characters furnished by, 43, 44

Sorites orbiculus, (Ehr.), 107

Specie.*, instability of in Foraminifera, 56-61

Spermatozoids, supposed, of Foraminifera, ."5, 36

Sphceroidina, genus, 7b, 185, 186; its history, 185;
external characters and internal structure, 185;
affinities, 185 ; geographical and geological distri-
bution, 18.5, 186

Sphserozoum punctatum (MUll.), 22

INDEX.

319

Spicular cord (of Carter), 25", 258

SpirUVuia, genus, 68, 180, ISI; its history, ISO;

external characters and internal structure, ISO ;

affinities, 180, 181 ; geographical and geological

distribution, 181 ; reproduction, 38
Spirillina arenacea (Will.), 1-11

— foliaeea (Will.), (i8
Spiroliua (D'Orb.), 88, 8!)

— agglutinans (IVOrb.), S!l, 144
Spiroline forms of Lituola, 89, 144
Spiroloculina, 75, 77
Sponges, related to Thalassicolina, 15, 22; to Carpen-

teria, ISS, 189; parasitic on Polytrcma, 2;)G
SqvnmuUna, genus, G7
Stichost^gues, 5, IGO
Supplemental Skeleton of Foraminifera, 50,51 ; of Cal-

carina, 220, 222; of Polystomella, 281-285
Surface-marking, value of in Foraminifera, 57-00

Test of Rhizopods, 11 ; of Arcella, 27 ; of Diffliigia,27 ;
of Gromia, 04

Textularia, genus, 189-192; its history, 189, 190;
external characters, 190-191 ; internal structure,
191; varieties, 191, 192; affinities, 192; geo-
graphical and geological distribution, 192

TrxTDLARiNyE, sub-faniily, 173, 175

Texture of the shell in Foraminifera, see Shell

Tlialaraopora vesiculosa (Mich.); 189

ThalassicoUa morum, 22
— uucleata, 23
• — punctata, 23

Thalassicollina, family, 22

Tilwporus, genus, 223, 229 ; its history, 223, 224 : —
T. vesicularis, external characters, 224, 225 ;
internal structure, 225, 226 : — T. haculatus,
external characters, 22 C ; internal structure, 227 ■
varieties, 228 ; affinities, 228 ; geographical and
geological distribution, 229

Trichodiscus, 20

Triloculina, 75, 78

Tiochamminu, genus, III, 142; its liisto;-y, 141;
external characters and interna) structure, 141,
142; affinities, 142; geographical and geological
distrilxilion, 142

Trochamniina charoides, 141

— incerta, 1 4 1

— infiata, 141

— irregularis, 142

— squamata, 141

Truncatulina (D'Orb.), 200, 207 ; reproduction of,

37, 39
Truncatulina lobatula, 201

— refulgens, 201, 207

— variabilis, 207
Tubular structure of shell, 45, 46

U.

Unilocular Foraminifera, 41, 42, 49

Uniloculina (D'Orb.), 75

jr»/(/e)'ma, genus, 169, 170; its history, 1(!9 ; external
characters and internal structure, 109, 170; affini-
ties, 170 ; geographical and geological distribution,
170

V.

Vaginulina (D'Orb.), IGO

Valve, of Jliliola, 70, 79; of Yalvulina, 14"; of Sphse-
ruidiua, 185

ViihuUna, genus, 146-148; its history, 14G; external
characters and internal structure, 146 ; varietal
forms 147; affinities, 148; geographical .and geo-
logical distribution, 148

Vermiculum (Mont.), 74

Verneuilina (D'Orb.), 190, 192

— arenacea, 192

— pygmsea, 192

Vertehriiliita, genus, 72-7-1 ; its history, 72 ; external
characters, 72,73 ; internal structure, 73 ; varieties
73, 74 ; affinities, 74 ; geographical and geological
distribution, 74

Vcrtebralina cassis, 72

— mucronata, 72

— striata, 72
Virguhua (D'Orb.), 194, 196

Vitreous texture of shell of Foraminifera, 45, 46
Vulvuhna (D'Orb.), 190, 192

W.

Webbina (D'Orb.), 69, 142.

rniNTF.D BY
J. E. ADLAED, BARTnOLOMKW CLOSE.

EXPLANATION OF THE PLATES.

PLATE I.

In this Plate is represented a series of typical forms of Rhizopoda, chiefly belonging to the Orders

LoBosA and Radiolaria.

Fig.

1. — Aciinophrys sol, with its radiating pseudopodia;
V, contractile vesicle. (After Claparede.)

2. — Actinophrys sol, in the act of engulphing a
Vorticella, a ; at v is seen the contractile
vesicle. {After Weston.)

3. — Aciinophrys sol, in the act of nearly completed
self-division (or incipient conjugation ?) ; v, v,
two contractile vesicles. (After Weston.)

4. — Actinophrys sol, in an earlier stage of self-
division (or more complete conjugation ?) ;
V, V, two contractile vesicles. (After Cla-
parede.)

5. — Eughjpha alveolata. (After Dujardin.)

6. — Plagiophrys cylindrica. (After Claparede.)

T. — Central portion of Acanthometra tetracopa.
(After Miiller.)

8. — Central portion of the siliceous framework of
Acanthometra echinoides ; a, furrowed entrance
to the canal of one of the rays. (After Cla-
parede.)

0. — Haliomma hexacanthum. (After Miiller.)
10. — Sphcerozoum punctatum ; at a, a is seen the
gelatinous investment in which are imbedded
the spheroidal bodies b, b. (After Miiller.)

Pig.

11. — One of the spheroids of Sphcerozoum punctatum
more highly magnified, showing its spicular
framework. (After Miiller.)

12. — Thalassicolla morum. (After Miiller.)

13. — One of the spicules of Thalassicolla morum.
(After Miiller.)

14. — Siliceous test of Collosphara Huxleyi. (After
Miiller.)

15. — Amceba radiosa, unier four different forms, a, b,
c, D ; n, nucleus. (After Auerbach.)

IG. — Amoeba princeps, under three difl"erent forms,
a, b, c. (After Auerbach.)

17. — Amaba bilimbosa, under two different forms, a, b;
n, nucleus. (After Auerbach.)

18. — Amoeba (?) porrecta. (After Schultze.)

19. — Arcella vulgaris. (After Ehrenberg.)

20. — Bifflugia globulosa. (After Ehrenberg.)

21. — Lagynis baltica, with the animal expanded at a,
and retracted at b into the posterior ex-
tremity of the test. (After Schultze.)

22. — Squamulina lavis ; a, its attached surface ; b, its
free surface, showing its oral aperture and the
pseudopodia extending themselves from it.
(After Schultze.)

Geo West ktli

riGS 1-6, ACTINOPHRYJMA.

15-

7,8. ACAIMTHOMETRINA. 9,P0LYCYSTINA. 10-14, TH ALAS SIC OLLINA-
■20, AMCEBINA. Zl.LAGYNIS. 22. SQUAMULINA.

W.West,™^.

PLATE II.

This Plate represents Lieberkiihnia Wageneri, the naked type of the Order Reticularia, with its pseudopodia
extended to no more than a third of the proportional length they often exhibit. (After Claparede.)

PLATE III.

In this Plate are shown three typical examples of testaceous Reticularia.

Fig.

1. — Discorbina globularis [Rosalina varians, Sch.),
with its pseudopodia put forth from the pores
of the lateral surface of the shell, as well as
from the apertural plane. (After Schultze.)

2.^Gromia oviformis, with its pseudopodia put forth,
not only from the aperture, but from the

Fig.

extension of the sarcode-body which invests
the whole surface of the "test." (After
Schultze.)
?y. — Miliola tenera, with its pseudopodia put forth
from the aperture only. (After Schultze.)

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PLATE IV.

This Plate is chiefly devoted to illustrations of the various forms of Reproduction among Rhizofoda generally,
and to representations of the sarcode-bodies of Orbitolites and Polystomella.

Fig.
1.-

10.—

11.

1:2.-

13..
11..

Portion of the body of an OrbitoUtes of the
complex type, in which the sarcode has
broken up into spherules ; a, a, superficial
segments j b, b, part of the annular stolon :
180 diam.

■Peculiar bodies (gemmules or ova ?) found in the
substance of different parts of the sarcode-
body of OrbitoUtes, showing successive stages
a, b, c, d, e, f, of binary subdivision ; ff, other
bodies of somewhat larger size, found in one
of the superficial chamberlets of a vertical
section : 130 diam.

■Rotalia, whose sarcode-body has dark spherules
imbedded in it. (After Schultze.)

•Reproduction of a triloculine Miliola ; a, parent
giving off young ; b, one of the young, more
highly magnified. (After Schultze.)

•Decalcified specimen of Truncatulina ; a, a, mem-
branous basis of shell ; b, sarcode ; c, c, c, c,
ova (?) with germinal vesicles and germinal
spots ; d, d, two segments destitute of ova.
(After Wright.)

■Amceba radiosa, with its nucleus (a) beginning to
enlarge and become granular, preparatory to
the development of sperm-cells. (After Carter.)

-One of the sperm-cells of Amwba radiosa, more
highly magnified, in its actinophorous stage,
previously to the hardening of the pellicle and
the development of the spermatic granules.
(After Carter.)

■Ammba verrucosa, of which the body is converted
into an ovisac filled with granuliferous germ-
cells. (After Carter.)

-Euglyjjha alveolata, in the interior of which have
been evolved from the nucleus delicate granu-
liferous sperm-cells. (After Carter.)

Euglyplia alveolata, of which the body is con-
verted into an ovisac filled with germ-cells.
(After Carter.)

EuDlypha alveolata, in which sperm-cells (a) and
germ-cells (b) are developed within the same
test J c, supernumerary scales. (After Carter.)

Portion of the sarcode-body a, a, of a Poti/sto-
niella, extruded by pressure from the fractured
shell; b,b, detached spheroids of the same; c,
another detached spheroid beginning to put
forth pseudopodial extensions resembling those
of a, a. (After Schultze.)

Nuclear (?) bodies imbedded in the sarcode of
Gromia. (After Schultze.)

Entire sarcode-body of an OrbitoUtes of the
simple type, the shell having been removed by
maceration in dilute acid ; in the peripheral
portion the segments of the sarcode-body
are wanting, and the structureless basis of the
shell is alone seen : 40 diam.

Kg.

15 — 20. — Central portions of the sarcode-bodies of
OrbitoUtes, showing varieties of the mode in
which the first annulus originates from the
circumambient segment ; a, primordial seg-
ment ; b, b' , circumambient segment ; c, seg-
ments of first annulus; d, peduncle connecting
primordial with circumambient segment ; e, e,
peduncles connecting circumambient segment
with first annulus : 84 diam.

21. — Central portion of the disk of an OrbitoUtes of
the simple type, showing an abnormal com-
mencement of growth.

22. — Pi'imitive disks produced by a large OrbitoUtes
of complex type, as seen at a on one of their
lateral surfaces, and at b edgewise, showing
the marginal pores.

23. — Part of the peripheral portion of Fig. 14 enlarged,
to show the ordinary mode in which the seg-
ments c, c, of each zone are connected by
radiating peduncles e, e, with the annular
stolon h, h, of the preceding zone, so as to
alternate with its segments ; showing also the
occasional interpolation of additional segments
c" , c" , whose peduncles, e , e , come off from
the segments of the preceding zone : 90 diam.

24. — Portion of one of the superficial strata of the
sarcode-body of an OrbitoUtes of complex type,
as seen from above ; aa' , a a' , a a , zones of
superficial segments, connected at their two
extremities with the annular stolons bb' , bb :
150 diam.

25. — Portion of the sarcode-bod}' of OrbitoUtes of com-
plex type, as seen in vertical plane ; a a, a a' ,
upper and lower rows of superficial segments,
each connected at its two extremities with the
annular stolons b b, and b' b' , of two zones;
the annular stolons b b, b b, connect the ex-
tremities of the columnar segments c, c, c, c,
which occasionally inosculate with each other,
and which conimuuicate with the iilternating
columns c', c , of the zone behind (whose ex-
tremities are in like manner connected by the
annular stolons V b') by rows of oblique pedun-
cles alternately passing towards one side and
the other : 150 diam. (n.b. This figure is
somewhat ideal, being made up from several
preparations ; but for every point which it
represents, these preparations give warranty.)

26. — Disk of OrbitoUtes repaired after fracture ; a, a,
the new zone by whose extension around the
broken margin the reparation has been
effected : 35 diam.

27.- — ^Disk of OrbitoUtes reproduced from a detached
fragment ; a, a, the zone from which the re-
paration seems to have proceeded : 35 diam.

28. — Sarcode-body of the animal of Polystomella
crispa, showing at a, a, a its segments, and
at b, b their retral processes. (After William-
son.)

Ceo West kth

TflTTest imp

Or^amzation and Reproduction of Forammifera

PLATE V.

This Plate is cliiefly devoted to illustrations of the varieties of form and development presented by the
Genera Nubecularia and Vertebralina. All the figures of each genus are drawn under the same magnifying
power, to show the remarkable variation which they exhibit in the size of their component parts.

Fig.
1. — Interior of a specimen o( Nubecularia m which
the spiral mode of growth continues with
unusual regularity. (See Fig. 6.)

2. — Interior of a specimen in which the regular
spire has very early given place to a succession
of large, irregularly-disposed chambers,

3. — Interior of a specimen in which the regular
spire has early given place to an assemblage
of chambers arranged without any succes-
sional regularity whatever.

4. — Under surface of a specimen in which the
dimensions of the chambers, which follow one
another in a regular spiral for about two
turns, are at first unusually small, and then
suddenly increase.

5. — Interior of a specimen in which the chambers
are unusually large from the commencement.

n. — External surface of a specimen resembling that
of which the interior is shown in Fig. 1.

7. — Interior of a specimen in which the original
spiral has very early given place to a rectilineal
series of very large chambers, the highest of
which seems not only to have continued the
series in nearly the same direction, but also to
have given forth an elongated chamber, which
doubles back (on the left side of the figure)
along the line of the preceding chambers.

S. — Exterior of a specimen formed by the acervuline
clustering of chambers around the horny stem
of a Zoophyte.

9. — Exterior of a specimen formed by the acervuline
clustering of chambers around a small branch
of Isis hippuris.

10. — Interior of part of a specimen in which a uni-
serial plan of growth is giving place to a more
extended arrangement ; the lowest chamber
opens into the next by a single aperture, but
the succeeding aperture is divided into two,
both leading to one chamber, the aperture of
which again is single. This chamber, how-
ever, opens by two apertures into two separate
chambers, each of which seems from its direc-
tion to have given origin to a distinct series.

13

14

Fig.

11. — Under side of a specimen in which a spiral suc-
cession of very small chambers is maintained
with great regularity for several turns ; near
its margin the chambers show a disposition to
become elongated, as in Fig. 13, in which case
the spiral would probably give place to a
cyclical plan of growth.

12. — Interior of a specimen in which a nniserial is
converted into a biserial arrangement of cham-
bers, apparently in accordance with the branch-
ing of the stem of a Zoophyte, probably an
Isis, to which it was attached.

Exterior of a specimen growing on the surface
of a flat shell, in which the chambers are ex-
traordinarily extended laterally.

Under side of a similar specimen, showing the
manner in which the original spiral plan of
growth soon gives place to another, in which
a series of chambers, extended laterally (as in
the preceding figure), communicate with each
other by multiple orifices.

15. — Interior of a specimen which connects such
aberrant forms with the more general type,
the chambers not departing much from the
form they usually have in the nniserial arrange-
ment, but communicating with each other by
multiple orifices instead of by a single wide
aperture.

16. — CortiKspira foliacea. (After Williamson.)

17. — Small milioloid variety of Vertebralina striata,
from the Tertiary sand of Baltjik.

18. — Renuline variety of Vertebralina striata, from
the Eocene at Hauteville.

19. — Articuline variety of Vertebralina striata, from
the Tertiary sand of Baltjik.

20. — Arrested variety of Vertebralina striata (the V.
cassis of D'Orbigny).

21. — Irregular specimen of the typical form of Verte-
bralina striata.

22. — Typical specimen of Vertebralina striata.

23. — Stunted specimen of Vertebralina striata.

24. — Dwarfed specimen of Vertebralina striata, from
a depth of 360 fathoms.

25. — Broad, compressed specimen of Vertebralina
striata.

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WrWcst,rarp.

PLATE VI.

With the exception of the last eight Figures, ^vhich represent different forms of Lituola, this Plate is devoted to a
series of illustrations of the principal varieties of the Milioliiie type.

Fig.
1.-

.3.-

4.—

6.— I

7.-
8-

13.—

14.-

15.-
16-

19-

34.-
35.-
36.-

-Lateral view oi -a Spiroloculina, of nearly circular
outline and almost continuously spiral mode
of growth.

-Similar view of a Spiroloculina, of very elongated
form and narrow aperture.

-Similar view of an elongated Quimjuelocu ina
with longitudinally furrowed surface.

Similar view of a more rounded Quinqueloculina,
■with longitudinally furrowed surface.

Similar view of a QuinquelociiUna, with strong
transverse plications.

Similar view of a Quinqueloculina, whose exterior
is arenaceous.

-Front view of a BUocuVuia, with smooth surface.

12. — Outline views of BilocuUiKe, to show the
variety in the forms of their apertures. (After
D'Orbigny.)

■Lateral view of TrilocuUna, with strong, super-
ficial reticulation.

—Lateral view of TrilocuUna, whose surface is in-
dented by minute pits.

-End view of CiucilocuUna. (After D'Orbigny.)

-18. — Apertures of Spirolondina and TrilocuUna,
showing three stages in the development of
the lingula.

-32. — Apertures of different specimens, and of
different parts of the same specimens, of a
Targe Biloculina from the Philippines, which
is represented with the last chamber laid open
in Fig. 33.

—Section of Hauerina, through the median plane.

— Lateral view of a deeply plicated Hauerina.

— A, Lateral view of Hauerina ; b, its cribriform
aperture.

Fig.

37. — A, Lateral view of Fabiilaria, with its surface
abraded in parts, so as to lay open the passages
immediately beneath ; b, end view, showing
its cribriform aperture.

38. — Transverse section of Fabularia, showing its
general biloculine plan of growth (the cham-
bers at the opposite sides meeting each other
along the line a, b), and the occupation of the
principal part of its chambers with solid shell-
substance, which is channelled out by inos-
culating passages ; a' , portion of this section
more enlarged, showing the junction along
the Hue a, b of the interior tuberculated wall
of oue chamber with the external pitted wall
of the preceding; a, a small portion of the
internal layer, showing the minute tubercles
projecting from its surface ; b, a small portion
of the external layer, showing the pits of its
internal surface, into which the tubercles of
the subjacent layer are received.

39, 40. — Lateral and front views of Lituula canariensis
[Nonionina Jeffrcysii, Will.)

41. — Portion of the shell of the same, highly magnified,
to show the manner in which it is made up of
agglutinated grains of saud.

42. — Portion of the shell of Lituola Soldanii, highly
magnified, sho^Ting the larger arenaceous par-
ticles to be imbedded in a cement composed
of amorphous particles united by an adhesive
exudation.

43. — Lituola Soldanii.

44. — Lituola nautiloidea ; a, lateral aspect, showing
the interior partly laid open by attrition ; b,
septal plane.

45. — Septal plane of another variety of the same.

40. — Another variety of the same.

Geo West. deLstlith

th.

FIGS. 1-33, MILIOLA. 34-36, HAUERINA. 37, 38,FABl]MRIA. 39-47, UTUOUV.

PLATE YII.

PeneropHs, with its Dendritine and Spiroline varieties.

Fig.
1.-

3.—

6.-

11.-

12.—

Ideal figure of the Dendritine variety of Pene-
ropHs, partly laid open, so as to show the
arrangement of its chambers, the nature of
their communieation by a single fissure of irre-
gular form (simpler in the earlier whorls, or
even replaced by a set of multiple pores), the
investment of the earlier whorls by the alar
prolongations of the chambers of the later, and
the detachment of the last convolution from
the preceding.

Portion of the surface of a specimen of Pene-
ropHs on which the plications are obsolete,
but the punctations are arranged in rows cor-
responding to them iu distance : 100 diam.

Portion of the surface of a specimen of PeneropHs
over which the punctations are scattered with-
out definite arrangement: 100 diam.

-Lateral view of Spiroline variety of PeneropHs ;
at a is seen the septal plane of its rectilineal
extension : 40 diam.

-Septal plane of another SpiroHne form, showing
a transition between the isolated pores of
PeneropHs and the coalesced fissures of Den-
dritina ; 40 diam.

-Lateral view of a young specimen of PeneropHs,
showing the greater turgidity of the spire and
the greater breadth of the septal plane (a) in
that stage, with a coiTCspouding ari'angement
of the multiple pores: 40 diam.

10. — Front views of young specimens of Pene-
ropHs, showing various departures fiom the
normal type in the form of the septal plane
and the disposition of the multiple pores :
40 diam.

-Lateral view of a young specimen of PeneropHs,
showing in the disposition of the apertures of
its septal plane (a) a tendency towards the
Dendritine variety : 40 diam.

Lateral view of a specimen of PeneropHs, of whicli
the later growth is rectilineal, as in the Spiroline
variety, but of which the form is compressed
and the pores quite distinct from each other,
though arranged in a double row, as seen at
a : 40 diam.

Fig.
13-

14.—

-Lateral view of a typical specimen of the Den-
dritine variety : 40 diam.

15.-

IG.-

17.-

18.-

19.—

20.-

21.—

Septal planes of the same — a, from the Ia.st
chamber ; b, from the preceding whorl ; c,
from an earlier whorl, — showing the progressive
increase in the complexity of the dendritic
aperture; al, at, alar prolongations of the
chambers of the earlier convolutions : 40
diam.

Septal plane of a specimen resembling in general
form that represented in Pig. 13, but showing
a want of coalescence of the fissures of which
the dendritic orifice is made up ; the ridge-
and-furrow arrangement of the walls of the
chambers is here prolonged in an unusual
manner over the borders of the septal plane :
100 diam.

Lateral view of a typical specimen of PeneropHs ;
at a is seen its long, narrow, septal plane, with
a single row of isolated pores arranged at
pretty regular intervals : 40 diam.

Front view of a Dendritine variety of peculiarly
turgid form, showing the lateral extension of
its aperture in accordance with the shape of
its septal plane : 40 diam.

Ideal figure of PeneropHs, partly laid open, so as
to show the arrangement of its chambers, the
nature of their communications by isolated
pores, and the difi'crcnces in the arrangement
of these in the earlier and in the later convo-
lutions, iu accordance with the form of the
septal plane.

Front view of a Dendritine variety of peculiarly
compressed form, showing the narrowing of
its aperture in accordance with the shape of
its septal plane : 40 diam.

Portion of the ordinary surface of PeneropHs,
showing its ridge-and-furrow plication and its
rows of minute punctations : 100 diam.

Portion of the ordinary surface of a Dendritina,
showing precisely similar characters : 100
diam.

Pl:iU-, VJI

Creo "Wsst, Jel el hll

WWcal.,iiiif>.

PENEROPLIS

PLATE VIII.

Orbiculina and Alveolina.

Fig.

1 — 5. — Successive stages of growth of the cyclical
type of Orbiculina adunca, showing the trans^i-
tion from the spiral to the cyclical plan of
growth : 16 diam.

('>. — Horizontal section of a disk in which the cyclical
type has heen completely attained, the original
spiral being surrounded by a succession of
annuli : 16 diam,

7 — 9. — Successive stages of growth of that type of
Orbiculina adunca in which the spiral plan
is maintained through life ; a, centre of the
spire, which forms the inner extremity of
every new zone ; c, its peripheral extremity ;
a b c, apertural surface : Ki diam.

10. — Horizontal section of a large spiral example of
Orbiculina adunca : 16 diam.

11. — Portion of the foregoing section much enlarged,
showing the chamberlets and their communica-
tions ; aa' , a a' , a a' , a a' , four zonal partitions,
perforated by the transverse passages b, b' ,
which communicate between the successive
galleries c c , c c' , c c' , that connect the
rows of chamberlets d, d, d, which are divided
by the transverse partitions e, e, e, e : 100
diam.

1^. — Vertical section of disk of Orbiculina adunca,
passing through its centre, 1, and showing the
mode in which this is invested by the suc-
cessive whorls, 2 2, 3, 3, 4, 4; a, multiple
zonal galleries between the columnar cham-
bers ; b, marginal openings of the radial
passages connecting successive zones : 100
diam.

Fig.
13.-

14.-

15.-

External aspect of Alveolina Quoii, showing its
longitudinal septal furrows, the spaces inter-
vening between which are crossed by secondary
furrows ; the elongated apertural plane is seen
to be perforated with rows of rounded pores,
of which those lying along the external margin
are smaller and more closely set than the rest ;
the apertural plane widens out greatly at its
two extremities, and the number of rows of
pores is greatly augmented, but they are less
regularly arranged : 40 diam.

-Transverse section of Alveolina Qtioii, showing
the division of the spire into principal seg-
ments indicated by the inflection of the super-
ficial laminae at a, a, a ; each of these seg-
ments is divided by the lamina; d, d^, d~
into a series of superposed chamberlets,
e, e', e', e", which open at their two extremities
into vertical spaces /, /, that extend through
the entire depth of the segment ; and in each
of these spaces are seen the orifices b, c, of
two galleries which pass along the entire
length of the shell, and connect the vertical
spaces with each other laterally : 80 diam.

-Longitudinal section of Alveolina Quoii, showing
the mode in which the spire is arranged
around the primordial chamber, and in which,
by the irregular multiplication of chamberlets
at the two extremities, its length is augmented
much more rapidly than its diameter. Each
convolution of the solid spire is seen to be
perforated along its external margin by a
closely set row of minute pores, which are the
transverse sections of the long, narrow, super-
ficial chamberlets ; and beneath these are
several rows of larger and less approximated
pores, which are the transverse sections of the
subjacent chamberlets : 40 diam.

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I'lOfJ.I LV,, OiiliiGULINA. I'iGS.13 It;, Al.ViaJl.l T-l A

PLATE IX.

All the figures in this Plate illustrate the structure of the calcareous disks of Orbitolites ; and the same
letters are used to mark corresponding parts throughout.

a. Primordial chamber.
b b V . Circumambient chamber.
c, c. Chamberlets of the concentric zones ; c , c , c' , c' , the same, as seen in vertical section.
d. Passage from the primordial to the circumambient chamber.
e, e, e. Radiating passages, connecting the chamberlets of successive zones.

f,f,f. Marginal pores on the external surface of the last annulus, in which the radiating passages terminate.
(/, g, (/. Inner surface of annulus separated by fracture from the outer surface of that to which it was applied,
showing the incompleteness on their inner side of the proper walls of the chamberlets, into each
of which a wide fissure is seen to open.
/(, /*, h. Annular galleries, connecting the chamberlets of their respective zones ; where the galleries are double,
as in figs. 7, 8, 9, A', /(', /(', point to the second series, and the space between the two constitutes
the intermediate stratum.
■ i, i, i. Superficial chamberlets, with the two passages at their extremities ; i', i', i', the same as seen in vertical
section.

Fig.
1.-

Ideal representation of a disk of the simple type,
the details of the different parts made up from
actual specimens ; showing the natural sur-
face, with the external indications of the con-
centric zones of transversely oval chamberlets ;
the natural margin, with the single row of
pores /, /, between the protuberances of the
chamberlets ; a portion of the interior c, c,
e, e, as displayed by a (horizontal) section
parallel to one of the surfaces ; another por-
tion c', c' , as displayed by a (vertical) section
perpendicular to this, passing in a radial
direction ; and another portion g, g, as dis-
played by a fracture following the circular
course of one of the zones.
2. — Vertical section of a disk of simple type :
30 diam.

section of a disk of simple type,
the excentricity of its early growth :

section of a disk of simple type,
a regularly concentric growth from

of simple type,
commencement :

3. — Horizontal
showing
35 diam,

i. — Horizontal
showing

very large central and circumambient cham-
bers : 35 diam.

5, — Horizontal section of a disk
showing a regularly spiral
90 diam.

6. — Portion of a horizontal section of a disk of
simple type, enlarged to show the mode of
connection of the chamberlets c, c, c, by
annular galleries h, h, h, from which come off
the radiating passages e, e, e, that lead to the
succeeding zones ; at c", c" are seen two in-
terpolated chamberlets, whose radiating pas-
sages come off from chamberlets of the zone
within : 120 diam.

7. — Ideal representation of a disk of complex type
(a portion of which is shown on a larger scale
in fig. 9), the details of the different parts

Fig.

made up from actual specimens ; showing the
natural surface, with the external indications
of concentric zones of narrow, rectilineal
chamberlets ; the natural margin, with its
multiple rows of pores lying in furrows /, /,
between the protuberances of the chamberlets ;
horizontal sections of the interior through
different planes, so as to lay open, at i, i,
the superficial chamberlets, at h, h, h, the
annular galleries into which these open be-
neath, at e, e, e, the cylindrical chamberlets of
the intermediate stratum, connected by the
radiating passages, and at h' h' , the lower set
of annular galleries ; at c , c', c , a vertical
section in the radial direction ; and at g, g, g,
the inner surface of an annulus, separated by
concentric fracture from that to which it was
applied.

8. — Vertical section of a disk of complex type :
k, first diflerentiation of superficial chamber-
lets from intermediate stratum ; /, summits of
interzonal partitions, forming the floors of the
superficial chamberlets ; m, m, passages of
communication between the superficial cham-
berlets and the annular galleries ; n, first dupli-
cation of the annular galleries, and differen-
tiation of the intermediate stratum : 30 diara.

9. — Portion of fig. 7, more enlarged.

10. — Marginal surface of a thick fossil disk, showing
the rows of pores /, /, lying in the furrows
between the protuberances of the cylindrical
chamberlets, the irregular junctions and subdi-
visions of these, and the incomplete diffe-
rentiation of the superficial chamberlets from
the intermediate stratum : 35 diam.

11. — Inner surface of a zone from the same disk,
separated by concentric fracture from that
which it enclosed : 35 diam.

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PLATE X.

All the figures in this Plate illustrate the structure of the different forms of Daclijlopora.

Fig.
1 —

18.

19.
20.

—Varietal forms o[ Dactylopora eruca, magnified
30 diameters, except Fig. 4 a, which is en-
larged to CO diameters. All these are from
recent specimens, except Figs. 4 and 8.

9 — 14. — Varietal forms of Dactylojmra anmilus ;
40 diam.

15. — Dactijlopora chjpelna, magnified 15 diameters;
A, small portion magnified 10 diameters.

16. — Fragment o( Daclijlopora diyitata ; 15 diam.

17. — Dactylopora reticulata; at a, magnified 15 dia-
meters, and at b, enlarged to 40 diameters ;
a a', juMctural interspaces, as seen externally;
b b', interior furrow, in which are seen the
internal entrances to the junctural interspaces;
c, c, outer walls of the chambers ; c c' , cavities
of the chambers laid open from the outside by
the attrition of their walls ; d, d, cavities of
the chambers laid open by vertical section ; e,
apertures of tlie chambers.

Another variety of Dactylopora reticulata, showing
the outer wall of each annulus between the
junctural interspaces a a', strengthened with
projecting ribs : 40 diam.

■The same viewed from above.

Specimen of the simplest variety of Dactylopora
cylindracea, magnified 15 diameters; — a, por-
tion of its external surface, enlarged to 40
diameters; n, portion of its fractured edge,
enlarged to 40 diameters, showing the gallery
a a, into which the chambers of the chambered
portion b, b open.

21. — Variety of Dactylopora reticulata, in which the
chambers are not arranged in regular annuli ;
thus leading towards D. (jlandulosa : 15 diam.

23. — Portion of a specimen resembling that sho.vn in
Fig. 20, laid open by acid from its exterior,
so as to show the cavities of the cliamljers, of
which the internal orifices are seen at a, a,
and which are surrounded by passages diverg-
ing from the necks of those orifices, the cross
sections of which are seen at b, b : 40 diam.

23. — Portion of a specimen of the more complex type
of Dactylopora cylindracea sliown in Fig. 29,
of which tlie external surface has been re-
moved by attrition : 15 diam.

2 1. — Portion of a specimen oi Dactylopora cylindracea,
resembling that shown in Fig. 20, hut more
highly developed, showing at a' a' the gallery
formed by the coalescence of the junctural
interspaces, communicating internally with the
general cavity of the cylinders by a row of
orifices in nipple-shaped protuberances, and

Fig.

opening externally into the chambers, b, b,
which are laid open by vertical section ; around
the neck of each of these chambers there ori-
ginates a set of diverging branches, d, d, which
pass round the chamber to reach the ex-
ternal surface, where they open into its funnel-
shaped depressions seen in section at c, c, c, c.
At A the same parts are represented as seen
in a horizontally fractured surface ; its differ-
ence from Fig. 20 a consisting in the more
complete continuity of the internal gallery,
a, a, and in the development of a thick wall
of solid shell-substance on the outside of the
chambered portion b, b : 40 diam.

25. — Portion of the edge of a fractured specimen of
Dactylopora glandulosa, showing at a, a, the
internal orifices of the chambers, and at b, li,
the junctural interspaces left between the pro-
jections of their external walls : 40 diam.

26.- — Portion of the internal surface of a specimen of
Dactylopora glandulosa (the chambers of which
are much smaller than the average) showing at
a, a, the mam miliary protuberance in which
the orifices of the chambers are situated, and
at b, b, the junctural interspaces here narrowed
to pores : 40 diam.

27, 28. — Portions of the external and internal surfaces
of the ordinary form o{ Dactylopora glandulosa ;
a, a, internal orifices of the chambers ; b, b,
junctural interspaces : 40 diam.

29. — Portion of the most complex type of Dactylopora
cylindracea, as seen under various aspects :
a, a, cavities of the chambers laid open ; b, b,
junctural canals, opening into the general
cavity of the cylinder by the orifices c, c, c, c :
at d, d, are seen the dilated citls de sac of
the junctural canals, from which originate the
diverging branches, e, e, wliich run towards
the surface, where they terminate in the funnel-
shaped depressions shown at g, g ; in the
lower part of the figure the diverging branches
are seen in cross section at e , e , whilst at /,
the external sheath has been so far removed as
to lay open the cuts de sac of two of the prin-
cipal canals from which they originate : 30
diam.

30. — Portion of the solid sheath of a specimen of the
same type of the preceding, which has been
subjected to the action of acid ; showing a
division by sutural lines into areola, in each of
which are seen the transverse sections of the
diverging branches of one of the junctural
canals : 40 diam.

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PLATE XI.

Trochammina, Lituola, ValvuUna, and Acicidaria.

Pig.

1 — 10. — -Various forms of Trochammina, magnified

50 diameters.
I .' — Trochammina squamata.
2. — Trochammina incerta.
3. — Trochammina charoides.
4. — Trochammina gordialis.
5. — Trochammina inflata.

6 — 10. — Various forms of Trochammina irreyularis.
1 1 — 14. — Placopsiline forms of Lituola cenomana ;

magnified 15 diameters.
15 — 26. — Various forms of ValvuUna; magnified

15 diameters.
15. — Typical example of ValvuUna trianffularis as seen

from its apex.
If). — Depressed variety of ValvuUna; the moutli of

the same shell is shown in Fig. 23.
17, 18. — Clavuline varieties of ValvuUna.

19, 25. — Bulimine varieties of ValvuUna.

20, 26. — Mouths of other examples of the same.

Fig.

21, 24. — Large valvular mouths of semioval variety

of ValvuUna.
22. — Portion of the shell of one of the outer chambers
of ValvuUna, showing the perforations in its
proper shelly layer in the part from which the
arenaceous incrustation has been most com-
pletely removed.

27 — 31 Various forms of Acicidaria, showing the

openings of the chambers, each of which, in
specimens whose natural surface has not been
destroyed by attrition, is surrounded by a lip,
as shown in Fig. 28 ; in Fig. 29, the attrition
has proceeded so far as to lay open the cavities
of the chambers ; magnified 20 diameters.
32. — Cylindrical specimen of Acicularia, of which the
chambers have been laid open by attrition,
and in which they present a honeycomb ar-
rangement ; magnified 40 diameters.

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PLATE XII.

The figures in this Plate represent various forms of tlie Nodosarine, Globigerine, and Textularine types, and

illustrate the structure of Fusuliiia.

Fig.

1.-
2.-
.'5.-

7.-
H.-

10.-
11.-
12.-
13.
14.-
15.-
16.-
17.-
18.-
19.-
20.-
21.
22.-
23.

at. I

-Lingulina costata. (After D'Orbigny.)
-Nodosaria hispida. (After D'Orbigny.)
-Cristellaria {Robulind) echinata. (After D'Or-
bigny.)
-Rimulina glabra. (After D'Orbigny.)
-GlanduUna lavigata. (After D'Orbigny.)
-Flabellina cordala. (After Reuss.)
-Orthocerina {Triplasia) 3Iiirchisoni. (After

Reuss.)
-Orbulina universa ; at a, is seen a small portion
of its surface more highly magnified, showing its
tuberculated aspect ; and at b, a small portion
reduced in thickness, and more highly m.ag-
nifieil, to show its two sets of pores.
-Ovulites margaritifera ; a, a small portion en-
larged, showing the hexagonal areolation of its
surface, with a pore in each areola.
- Ovulites elongata.
-Globigerina helicina.
-Pullenia bulloides.
Spheeroidina austriaca.
-Animal of Textularia.
-Vulvulina gramen. (After D'Orbigny.)
-Chrysadilina gradata. (After D'Orbigny.)
-Cuneolina pavonia. (After D'Orbigny.)
-Bulimina Presli. (After Reuss.)
-Bulimina Buchiana. (After D'Orbigny.)
-Bulimina pynda. (After D'Orbigny.)
-Bulimina [Roberiina) arctica. (After D'Orbigny.)
-Bolivina costata. (After D'Orbigny.)
-Cassidulina [Ehrenbergind) serrata. (After
Reuss.)

Cast of the chambers of a FusuUna of simple-
type, showing the alar prolongations extending
on either side nearly in straight lines from the
median segments. (After Ehrenberg.)

Fig.

(After D'Orbigny.)

(After Schultze.)

26.-

28.—

20.

Transverse section of Fusulina, through its
centre, showing at a, a, the aperture con-
necting together the principal chambers c, c ;
and at b, b, the origins of the alar prolonga-
tions from the principal chambers.

-Portion of the same section more enlarged,
showing an appearance of tubularity in the
outer walls of the chambers.

Ideal view of Fusulina laid open in different
modes, to show its internal structure ; at a, is
seen the single fissured aperture situated in
the centre of the length of the shell (of which
nearly a half on the left hand has been re-
moved by a transverse section), communicating
with c, c, the principal chambers laid open
from the surface ; near the right hand ex-
tremity the septal plane e, e has been removed
to show the subdivision of the alar prolonga-
tions by the elongated secondary septa /, /,
which do not quite reach the spiral lamina, a
continuous gallery being left at b, b, by which
the chamberlets are connected ; at d the in-
terior has been laid open by the removal of
the septal plane, showing the necklace-like
form of the alar prolongations, and their alter-
nating arrangement.

A portion of this last more enlarged, showing at
c, c, c , the cavities of the chamberlets, and at
b' , b, b the communicating jiassages ; a section
in the line a a will pass alternately through
the chamberlet c , and the gallery b' , giving
rise to the appearances shown in fig. 29.

Transverse section taken near the extremity,
showing the elongation of the septa, and
their apparent divarication to give passage to
the narrow galleries U b' connecting the cham-
berlets, of the alar prolongations.

Plate HI.

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PLATE XIII.

The figures in this Plate represeut various forms of the RotaUne tvpe, and illustrate tbe structure of AmpMstegina.

Pig.
1.-

2..
3.

4.-

5.-
6.-

v.-
8.

9.
10.-

n.-

13.-
13-
14.-

15.-
16.-

17.-

18.-
19.

-Portion of the shell of an Acervuline Planorbu-
lina, much enlarged, as seen at a in its super-
ficial aspect, and at b in vertical section.
(After Schultze.)

-Discorbina vestcularis, seen on its upper side.

-The same, as seen on its lower side.

-Pulvinulina vermlculata, seen on its upper side ;
at a is shown a small portion more enlarged
(seen as an opaque object), showing its granular
surface.

-The same, as seen on its under surface.

-Portions of the under surface enlarged, showing
at a its large orbuline pores, and at b its
minute tubuli arranged in clusters.

-Rutalia Schroeteriana, viewed obliquely.

-Transverse section of the same ; a, bifurcation
of the canals.

-Vertical section of the same.

-Side view of Cijmbalopora [Rosallna) Poeiji.

-Basal view of the same.

-Basal view of another specimen of the same.

-Planorhullna vulyaris, as seen on its attached side.

-Portion of the margin of the same, much more
enlarged, showing the communication of the
chambers by the apertural neclis a, a.

-Portion of the free surface of tropical variety of
Planorbulina vulgaris, showing its prominent
tubercles.

-PateUina corriigata, as seen from its upper sur-
face, showing a central and circumambient
chamber resembling that of Orbilolites, sur-
rounded by annular rows of chamlierlcts.

-The same viewed from the under side, showing
the prolongation of the chamberlets towards
the centre, and the filling-up of the umbilical
cavity by a secondary growth.

-Pohjtrema rubra ; a, globular form ; b, arbores-
cent form.

—Portions of its surface more enlarged ; a, porous
areolae bounded by solid shell-substance ; b,
openings of large canals at the ends of the
branches.

Fig.
20.-

21.-
22.-

23.-
24.-

25.

26.-

28.—

29.-

Sections of the same, showing at a, a, large
canals formed by the coalescence of cham-
berlets, and at b, b, solid columns formed by
the deposit of calcareous matter in excess.

Calcarina calcar. (After D'Orbigny.)

Upper surface of Amphlsteginn mamniUlata.
(After D'Orbigny.)

Lower surface of the same.

End view of the same, showing the mouth, and
the superficial granular deposit in its neigh-
bourhood.

Horizontal section of Amphisiegina, showing the
disposition of the chambers, the singleness of
the septa, and the tuberculated surface of the
septal planes and of the external surface of
the penultimate whorl ; a, small portion more
enlarged, to show the free openings of the
tubuli on the internal surface of the chambers.

-Vertical scctiou of the same ; showing at a a,
the alar lobes of the upper surface, and at
a' a the alar lobes of the lower surface ;

b, b' , the upper and lower umbilical bosses ;

c, c\ c', c^, non-tubular portion of the spiral
lamina at the margin of the successive con-
volutions ; d, d' , thin cliamber-wall of the
last convolution ; e, e', thickened chamber-
wall of penultimate convolution ; /, the
aperture ; g, h, line marking the declination
of the spire ; i, apparent subdivision of the
outer wall of the convolution, resulting from
the backward elougation of the chambers.

-Cast of the interior of Amphistegina, showing
the disposition of the alar prolongations of
the upper side.

Cast of the interior of AmpMstegina, showing
the nearly complete detaclimenc of the alar
prolongations on the under side from the
principal segments, with which they are only
connected by the narrow necks a, a, and their
intercalation as " astral lobes."

Cast of the interior of Amphistegina, showing a
subdivision of the alar lubes of the upper side
by incomplete partitions.

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PLATE XIV.

All the figures in this Plate illustrate the structure of Calcarina.

Fig.

1. — Characteristic specimen of the Maltese variety of
Calcarina SpengJeri, showing its large club-
shaped radiating outgrowths, the tubercles of
the central part of its surface, and the septal
divisions of the last half turn of the spire,
hidden elsewhere by the overgrowth of the
intermediate skeleton; magnified 12 dia-
meters.

2.' — Characteristic specimen of the Philippine variety
of C. Spengleri, showing the tendency to elon-
gation and subdivision of its radiating out-
growths; magnified 12 diameters.

In the succeeding figures, the same letters are
used to indicate corresponding parts, as follows :
a, a}, a', d", o', interior chambers of successive
convolutions ; h, h, b, external surface of the
proper walls of the chambers, shown in section
at b' b' b'.

c, c, c, septal pores, constituting the only
communication between the chambers.

d,d,d, intermediate or supplemental skeleton,
the progressive increase of the thickness of
which in the last convolution is shown at
d, d\ d", d\ fig. 4.

e, e, e, e, summits of the solid tubercles,
which are seen in section at e , e , e .

f, /, /, radiating outgrowths, of which the
furrowed surface is shown in fig. 8, whilst
their canal-system and its connections are
better displayed in fig. 4, where also is shown
the diiference in the stage of growth at which
the radiating outgrowths /, /, /, /, /', f, re-

FlG.

3.

4.

5.—;

6.

spectively originate from the intermediate
skeleton.

Section of the disk of Calcarina taken through
the axis of the spire ; magnified 50 diameters.

Section of the disk and radiating outgrowths
of Calcarina taken through the later whorls
(thereby passing over the inner ones) trans-
versely to the axis of the spire ; magnified 50
diameters.

Small specimen of Calcarina, of which the spire
has detached itself from the disk, and has
" run wild ;" magnified 12 diameters.

-Young specimen of hispid variety of Calcarina ;
magnified 30 diameters.

Portion of the surface of the preceding specimen,
more highly magnified, showing that the
spines are tubular, being formed around the
pseudopodia as they issue from the shell.

-Ideal representation of Calcarina, hiid open to
show the relations of its different parts, the
apes of its turbinoid spire being placed down-
wards for more convenient display.

Portion of a section passing through the inter-
mediate skeleton in the immediate neigh-
bourhood of one of the chambers, showing the
free distribution of the canal-system; mag-
nified 75 diameters.
— Portion of a section passing through the inter-
mediate skeleton near the surface of the disk,
showing the distribution of the orifices of the
canals around the solid cones, transversely di-
vided at e, e, e; magnified 75 diameters.

8.

9.—

Plate XIV.

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PLATE XV.

All the figures in this Plate illustrate the structure of Tinoporus.

Fig.

1. — External view of a couical specimen of Tino-
porus vesicularis ; magnified 23 diameters.

2. — Portion of a section of the same, parallel to the
base, showing an irregularly concentric ar-
rangement of chambers, the floors of which are
perforated with numerous foramina; magnified
50 diameters.

3. — Section of the same in the direction of the axis
of the cone, showang at a the spherical pri-
mordial chamber, and at b and c the chambers
first connected with it on either side ; show-
ing also the manner in which the succes-
sively-formed chambers are piled one upon
another vertically, with the large lateral
orifices of communication between adjacent
chambers ; magnified 50 diameters.

4. — Ideal representation of a portion of the same, to
show the relations of the chambers, which are
divided from each other horizontally by cribri-
form floors, and laterally by solid walls, in
■which there are large apertures, a, a, a, open-
ing into adjacent chambers.

5. — Australian variety of Tinoporus baculatus, en-
larged 50 diameters, to show the areolated
character of the surface of the disc, with
elevated tubercles disposed between the

Fig.

areolse, and the furrowed surface of the ra-
diating prolongations.

6, 7 . — Other specimens of the same variety, showing
marked difierences in conformation ; magnified
20 diameters.

8, 9. — Specimens of the Philippine variety of the
same ; magnified 12 diameters.

10. — Portion of a section of the Philippine variety,
showing at a the canal-system interposed be-
tween the chambers, and at b its reticular
distribution in the solid commencement of one
of the radiating outgrowths.

11. — Section of the basal portion of one of the radiating
outgrowths of T. baculatus, showing the man-
ner in which the chambers are clustered round
the axis, and in which the axis is traversed by
canals radiating from its centre to its circum-
ference.

12. — Section of the central portion of T. baculatus
passing through the median plane, showing at
a, a, its regularly spiral commencement (not
distinguishable from that of a Calcarina), the
origin of the spines from the intermediate
skeleton of the spire, aud the early exchange of
the spiral type for an irregular clustering of the
chambers, as seen at b ; magnified 80 diameters.

Plate ly.

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GeoTfest.lnh.

TINOPORUS.

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PLATE XVI.

All the figures in this Plate illustrate the structure of Polystomella, and the same letters are used to

mark corresponding parts throughout.

a, (^, or. Chambers of successive whorls ; in figs. 7, 8, 9, consecutive segments of the same whorl.
b, h^, b^, 6'. Septa of alternating whorls.

c, c, c, c. Septal apertures ; in figs. 7, 9, c' c', the stolons passing through those apertures.
d d! , d d' . Meridional canals.

e, e. Spiral canals ; e e' , the same transversely divided.
/, /. Diverging canals.
9 o' 1 'J 9 • Surface of the last-formed portion of the spiral lamina, showing a row of furrows passing
across the septal bands, into which the diverging canals open in immediate contiguity to them.
h li , h li . Older portion of the spiral lamina, showing the replacement of each series of furrows by two
rows of punctations.
i i' , i i'. Surface of the interior whorl, showing the obliteration of the septal bands, and the rows of

dimpled depressions into which the diverging canals open.
k, k, k. Retral prolongations of the segments ; in fig. 5, k', k', mark the cuh de sac in which they are
lodged in the shell of Pohjstomella crispa.
I I, I' I' . Exogenous deposit of shell filling up the depressions in the umbilical regions of both lateral
surfaces, and traversed by straight vertical canals.

Fig.

1. — Ideal representation of a specimen of Polysto-
mella craticuluta, laid open to show its internal
structure, and the umbilical deposit removed
from its upper surface to show the spiral
canal.

2. — Polystomella craticulala, as viewed at a in its
lateral aspect, showing the septal ridges and
the intermediate double rows of punctations,
and the irregular distribution of similar punc-
tations over the umbilical deposit of exogenous
substance ; the same shown in front at b, so
as to bring into view the septal plane, and its
row of multiple apertures.

3. — Vertical section of P. craticulala ; magnified 20
diameters.

4. — Side view of P. crispa, showing the fossettes
along the anterior margin of each septal band ;
magnified 25 diameters.

Fig.

6.—

Vertical section of P. crispa ; magnified 50
diameters.

Segments from two consecutive whorls of the
animal body of P. crispa, showing their forms
and connections ; magnified 100 diameters.

Portion of a cast of three adjacent segments of
the same whorl of P. craticulafa, showing
their forms and connections ; magnified 40
diameters.

Fragment of P. craticulala, showing the furrowed
internal surface of three of the chambers, and
the relation of the furrows to the diverging
canals ; magnified 40 diameters.

Internal cast of the chambers and canals of
Polystomella craticulala, representing the form
of the body and the distribution of the canal-
system ; magnified 40 diameters.

Plate xyi.

(■.to."West,daeiJiili

POLYSTOMEI.LA.

PLATE XVII.

All the figures in this Plate illustrate the structure of Operculina complanata.

1. Ideal figure of Operculina, laid open to show its

structure : a, a, a, marginal cord, divided
transversely at a', so as to show the orifices
of its canals, the distribution of which is seen
at a" a" in tangential section, and at a" a"
in section through the median plane ; b, b, b, ex-
ternal surface of the chambers, marked out by
the septal bands ; c, c, interior of the chambers
of the outer whorl, the alar prolongations of
which extend, as shown at c', c', over the sur-
face of the inner whorl, towards the centre of
the spire ; d, d, septa dividing the chambers,
formed by two lamellae, between which lie the
interseptal canals, whose smaller branches are
seen irregularly divided in the septa d' , d', while
in the septum d", d,'' one of the principal
trunks is laid open through its whole length ;
at the approach of each septum to the marginal
whorl is seen the fissure, e, e, e, e', which
forms the principal communication between the
chambers ; /, /, the secondary orifices ; g, g,
the distribution of the interseptal system of
canals, which branch from the two spiral
canals h, h ; and. at i, i are seen the conoidal
columns of nou-tubnlar shell-substance that
overlie the septa, forming tubercular projec-
tions on the surface, and frequently penetrated
by branches of the interseptal canals.

2. — Portion of the outermost and penultimate con-
volutions, laid open by vertical fracture : a, a ,
e, e, /, /?, y, h, h, as in the last figure ; h', h' ,
transverse sections of spiral canals ; k, k, spiral
lamina, that of the last whorl coalescing with
that of the penultimate whorl at k' , k' , and
augmenting its thickness ; 75 diameters.

3. — Portion of the marginal cord, a" , a", as seen in
a section passing through the median plane,
showing the fusiform spaces formed by the
inosculation of the canals ; 120 diameters.

4. — Portion of a section through the median plane,
showing the connection of one of the inter-
septal canals g, lying in the midst of non-
tubular substance, with the reticulation of
the marginal cord a" a'" ; 100 diameters.

3. — Exterior of the marginal cord, showing at a, a
its furrowed surface, a a the transverse section
of its canal system, and at li h' the trans-
verse sections of the spiral canals which lie
just at its junction with the ordinary tu-

FlG.

6.-

bular substance k, k, forming the lateral walls
of the chambers.

-Section through the median plane of a very
young OpercuUna, showing the origin of the
spire from a globular primordial chamber, and
showing the presence of the spiral canal and
of its extensions even in the very first convolu-
tions ; 75 diameters.

-Portion of a vertical tangential section passing
near the margin of the innermost convolution
of a young Operculina, and afl'ording a most
advantageous view of its canal-system ; «', a ,
marginal cord of the inner convolution ; g, g,
interseptal canals, springing from h, h, the
spiral canals ; i, i, cones of non-tubular sub-
stance which take the place of the ordinary
tubular substance of the spiral lamina, k, k, at
the parts where this is joined by the septa ;
80 diameters.

8

9.-

Portions of the spiral lamina magnified 250
diameters, sliowing at a its prismatic appear-
ance, with a tubulus in the centre of each
prism, and at a the large orifices of the tubuli
upon its internal surface.

•Very thin section of a portion of the spiral
lamina, showing the ordinary appearance of its
tubuli divided transversely, with a delicate
areolation between them ; 100 diameters.

10. — Vertical section of the inner convolutions, which
has happened to pass close to the primordial
chamber and the one that springs from it, and
which shows at a, a, the two spiral canals
running along their exterior ; 80 diameters.

11. — Vertical section of a small Operculina, showing
the general distribution of its interseptal canal-
system, and the marked difference in thickness
between the spiral lamina of the last and that
of the penultimate convolutions ; 40 diameters.

12. — Section of the spiral lamina of a tuberculated
variety, showing the partial deficiency of the
tubuli in certain spots, b, b, as well as in the
septal bands a a, a' a', with their crowding to-
gether in the neighbourhood of these ; 120
diameters.

Internal surface of the spiral lamina of another
chamber of the same, showing the uniform
distribution of the tubuli, except along the
septal bands, and the comparatively large size
of their orifices ; 120 diameters.

1

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PLATE XVIII.

All the figures in this Plate illustrate the structure of Nmnmulina ; and the same letters indicate corresponding

parts throughout.

a, a. Marginal cord, as seen in section through the median plane ; a', a', the marginal cord, as seen in

sections dividing it transversely ; a", furrowed surface of the marginal cord.
h, h. Septa dividing the chambers of the median plane; b' , h' , prolongations of those septa over the

lateral surface of the included whorl; b" , b" , bifurcating prolongations.
c. Apertural fissure.

d, d. Spiral lamina enclosing the chambers of the median plane ; d', d' , investing layers of the spiral lamina.

e, e. Columns of non-t\ibular substance, divided longitudinally by sections at right angles to the median

plane ; e , e , the same divided by transverse sections.
/, /. luterseptal canals, as seen traversing the septa longitudinally ; /, /', the same, as seen in transverse
section.

Fig.

1. — Portion of A^. gi:ehensis, showing the alar pro-
longations of the marginal chambers over the
included whorl. (After D'Archiac.)

2. — Portion of a vertical section of N. Itevigata,
showing the tubular structure of the spiral
lamina, with non-tubular columns interposed,
the canal-system of the marginal cord as seen in
a transverse section, and the apertural fissure.

3. — Portion of N. garansensis, showing the reticular
disposition of the alar prolongations of its
septa, forming numerous isolated chamberlets.
(After D'Archiac.)

4. — Small portion of a thin section of N. Icevigata
through the median plane, showing the distri-
bution of the canal-system in the septa and
marginal cord.

5. — Larger portion of the same section, less highly
magnified, showing the general disposition of
the spiral convolutions.

6. — Portion of another section taken parallel to the
median plane, highly magnified, showing the
tubular structure of the spiral lamina, the
transparent, non-tubular structure of the septal
bands, and the distribution of the canals in
the septa and marginal cord.

7. — Portion of N. lavigata laid open by a vertical

Fig.

fracture, showing the furrowed surface of the
marginal cord of the included whorl, and parts of
two large spiral canals, from which proceed the
interseptal canals that pass towards the mar-
ginal cord of the outer convolution.
8. — Portion of N. Icevigata as laid open by vertical
fracture in the direction transverse to the
radius of the disk, showing the interseptal
canals transversely divided, and the columns
of non-tubular substance commencing on the
septa of the median layer, and extending to
the surface through the successive layers of
the spiral lamina.
9. — Portion of A^. kevigaia, showing the sub-reticular
disposition of the alar prolongations of the
septa.

10. — Vertical section of N. lavigaia, showing the
septa and apertural fissures of the chambers
of the median plane, the continuity of the
successive layers of the spiral lamina over
both lateral surfaces, the interposition of the
alar prolongations of the chambers, with their
dividing septa between those layers, and the
columns of non-tubular substance which pass
sometimes through one or two of them, some-
times through several.

PlaiB XVIII.

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FU^MULITES.

PLATE XIX.

Heterostegina and Cyclochjpeus.

Fig.

1. — Surface view of a full-grown specimen of Heteros-
tegina, showing its tendency to assume the
discoidal form by the opening out of the spire ;
a, b, c, thickened margin of the spire ; c, d, a,
its growing edge or septal plane : 10 diam.

2. — General view of a disk of Cycloclypeus, showing
the aspect of its surface, and the appearances
presented by horizontal and vertical sections :
12 diam.

3. — Vertical section of the shelly lamina enclosing
the chambers of Cycloclypeus, showing its
lamellated structure ; a, a, one of the cones
of non-tubular substance replacing the ordi-
nary tubular substance b, b, over the septa;
c, section of one of the interseptal canals : 150
diam.

4. — Thin section of the same lamina taken parallel
to the surface of the disk, showing its mi-
nutely tubular structure, except where it over-
lies the annular septum a o ,■ at c c are seen
the divided ends of vertical branches of the
interseptal system of canals : 100 diam.

5. — Ideal figure of a portion of a Cycloclypeus disk,
laid open to show the details of its structure ;
a, a, a, upper lamina, consisting of superim-
posed tubular lamellae ; b, b, b, lower stratum ;
c, c, c, cones of non-tubular substance, some-
times perforated by larger canals ; d, d, d,
their bases, forming tubercles on the surface ;
e, e, plates of non-tubular substance overlying
the septa ; /, /, passages of communication be-
tween the chambers through the inter-annular
partitions, as seen in section ; ff, g, the same,
as seen from the interior of the chambers ;
h, h, interseptal canals cut across ; ;, a chara-

FlG.

ber on the walls of which the system of in-
terseptal canals is represented as fully dis-
played ; k, k, passage of the principal canals
along the line of junction between the roof of
the chambers and the vertical septa: 60 diam.
6. — Diagram of a single chamber of Cycloclypeus,
showing its relations to other chambers and to
the interseptal system of canals ; a, cavity of
chamber ; b, b, adjacent chambers of the same
annulus, each separated from a by a double
septum ; c, c', and d, d' , chambers of external
and internal annuli, separated from a by the
partitions e c, e e , but communicating with it
by the passages/, /,/,/"; in the septa between
a and b, b, are seen the interseptal canals g, g,
each of which sends two oblique branches
across the annular septa, to communicate with
corresponding canals i, i in the septa dividing
c, c and d, d' ; these interseptal canals seem
to communicate by short, lateral twigs with
the cavities of the adjacent chambers, whilst
at g' g they become connected with vertical
branches, which unite them with those of other
planes ; at h, h, h' , h' are seen the canals
proper to the annular septa.
7. — Section of Cycloclypeus passing through its
median chambered plane, showing portions of
four annuli, 1 1, 2 2, 3 3, 4 4, with the general
relations of their chambers and their connec-
tion by the passages a b, a b, the double septa
by which they are separated, the thickening
of the annular partitions by intermediate de-
posit, and (in parts) the interseptal system of
canals : 36 diam.

Pl.iie AIX.

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PLATE XX.

All the figures in this Plate illustrate the structure of Orbitoides.

Fig.

1 — Ideal representation of a half disk of 0. Fortisii,
laid open by vertical and horizontal sections,
showing the resemblance of its median cham-
bered plane to that of Cydoclypeus, and the in-
terposition of flattened charaberlets between the
lamellae enclosing them on either side: 20 diam.

2. — Ideal representation of a small portion of a
similar disk, more highly magnified ; a, a, a,
interior of the chambers of the median plane ;
c, c, their passages of communication with the
chamberlets of the annuli internal and ex-
ternal to them ; d, d, oblique passages of
communication between the chamberlets of
the superficial layers ; e, e, non-tubular cones ;
h, h, canal system : 60 diam.

3. — Section of the chambered structure of the
median plane, showing the septa to be com-
posed of two lamellae, with an interseptal
canal-system : 50 diam.

4. — Section of the chambered structure of the
superficial plane, showing the irregular form
of the chamberlets, and the tubularity of the
horizontal partitions : 50 diam.

5. — Section of the chambered structure of the
median plane of 0. Manlelli, showing the com-
munications of the chambers of successive
annuli by the oblique passages, a b, a b, and
showing also an appearance of communica-
tions between the adjacent chambers of the
same annuli at their inner margin : 60 diam.

6. — Vertical section of 0. Mantelli, showing at a, a,
the chambered structure of the median plane ;
c, c, apertures of communication between its
chambers; d, d, oblique passages between the
chamberlets of the superficial layers; /, /,
interseptal canals : 60 diam.

7. — Vertical section of a small specimen of 0. For-
tisii, showing a strong resemblance to a cor-
responding section of Nummulina : 20 diam.

8. — Portion of section of O. MantelU, passing some-
what obliquely from the chambers of the
median plane, seen in the lower part of the
figure, to those of the superficial layer seen in
the upper part ; showing in the former the
lateral communications between the chambers :
50 diam.

9.— A similar section from another part of the same
specimen, showing at its lower part a different
form of the chambers of the median plane

Fig.

10.—

11.-

11*.

13.—

li-

15.—

16.-

and the interseptal canals between the two
lamellae of their septa, and showing at its
upper part the communications between the
chambers of the superficial layer : 50 diam.

Vertical section of a large, thick specimen of 0.
Fortisii, showing the very small proportion
which its median chambered plane bears to
its superficial layers (that of the under side
having been partly broken a-^vay), and showing
the conical pillars of solid shell-substance,
traversed by canals : 10 diam.

Portion of the same section more enlarged, show-
ing at e, e, one of the solid pillars, traversed
by brauches of the canal-system: 100 diam.

—Vertical section of a very small specimen of
O. Mantelli, showing the very large size of its
primordial chamber, and the unusual height of
the charaberlets of its superficial layers: 20 diam.

Section of the superficial layer of O. Fortisii,
taken parallel and near to the surface, show-
ing the verj' large size of the solid jiillars
e, e, e : 100 diam.

Similar section, taken nearer the median plane
(being part of the section represented on a
smaller scale in fig. 14), showing the smaller
size of the pillars, and their penetration by
branches of the canal-system : 100 diam.

Section of 0. Fortisii, taken in the same direc-
tion as the preceding, but much less enlarged,
and passing in part through the chambered
median plane, and in part through one of the
superficial layers ; in the former is seen the in-
completeness of several of the annuli : 20 diam.

\ ertical section of a large, thick specimen of
O. Fortisii, showing the median chambered
plane divided transversely, the great thickness
of the layers by which it is invested, and the
prolongation of the superficial parts of these
so as to meet at the margin and thus com-
pletely to enclose the median portion : 16 diam.

Portion of a similar section more enlarged, show-
ing the chambers a, a, a, of the median plane,
divided by double septa, between the lamellje
of which are seen indications of interseptal
canals ; above these are seen the piles of
flattened chamberlets of the superficial plane,
communicating by the oblique passages d, d,
and partly separated from each other by the
columns e, e, of solid shell-substance : 40 diam

Plate JQC.

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ORBITOIDES

■WWe.i

PLATE XXI.

All the figures in this Plate illustrate the structure of Carpenteria.

Fig.
1-

G.-

8. 9

10.-

11.

5. — Interior of the first-formed chambers of five
specimens, showing their Globigerine cha-
racter and arrangement ; at a, a, are shown
the remains of the yellowish-brown spougeous
substance by which those chambers were occu-
pied : 50 diam.

-Portion of a group attached to the surface of
Poriies (Coral) : 5 diara.

-Isolated specimen growing on the shell of Pecten,
in which the chambers of the last whorl
diverge so widely at the base of the cone as
to be in great degree separated from each
other : 25 diam.

— External apertures at the apex of the cone of
two specimenSj showing their peculiarly Milio-
line character : 20 diam.

-Portion of a specimen partially laid open by grind-
ing away the apical portion of the cone ;
showing at a the vertical funnel transversely
divided, at b its communication with the last
chamber, at c its communication with the
penultimate chamber ; d, d}, and d^, three of
the complete septa dividing the principal
chambers ; e, ei, e", secondary septa, partially
dividing the principal chambers, but not ex-
tending to their central portion; f,f^,f-, in-
complete septa projecting inwards from the
external wall, but not crossing the cavity of
the chamber to reach the opposite wall : 20
diam.

— Section of a very flat specimen, parallel to the
base of its cone, but not far from its apex ;
a, b, c, d, as in the last figure ; g and ^', por-
tions of the canal-system : in some of the
chambers are seen spicules resembling those
of Sponges : 20 diam.

— Portion of the external wall, showing the areo-
lated aspect it derives from the gentle con-
vexities into which it rises between the reti-
culations that project on its internal surface ;

Fig.

at a is shown the natural external surface on
which the foramina are regularly disposed ; at
b that surface has been removed by grinding,
so as to bring into view the inner layer of the
wall, on which the foramina are seen to be
deficient along the projecting ribs, but to be
more closely set together in the portions sur-
rounded by these (see fig. 16) : 30 diam.
13. — Portion of a section taken in the same direction
as Fig. 11, but represented on a larger scale,
showing the annulations of the foramina that
are seen obliquely traversing the shell, and the
two layers of which not only the principal
septa «, a, but also the incomplete septum b,
are formed, with the cauals included between
them; at c is seen a large dilatation of one
of the canals : 75 diam.
14. — Portion of the group of Carpenteria growing on

the surface of Poriies, of the natural size.
15. — An unusually large specimen, of the actual size.
16.-^Portion of the external wall of a specimen which
has been thinned away by the action of acid,
showing the reticulated arrangement of the
incomplete septa ; the spaces included in the
reticulations are in some instances covered in
by a thin layer of the shelly wall which has
not been removed ; but in most other cases
this wall has been eaten away by the acid in
the central portion of the reticulation, so as
to display the dark, spiculiferous substance
■within : 30 diam.
17. — Siliceous spicules (resembling those of Hali-
chondria) from the spongeous tissue occupying
the chambers of Carpenteria : 75 diam.
18. — Section traversing the external wall of one of
the chambers perpendicularly to its surface,
showing at a, a, the annulated foramina by
which it is traversed, and at b, b, b, sections of
the imperfect septa on which the foramina do
not open : 75 diam.

l^at.:.XXL

Geo.TWest, del et lnii

CAR.PENTERIA.

ifistjimp.

PLATE XXIT.

All the figures in this Plate represent casts of tlie interior of Foraminifera of different types, described
and figured by Prof. Elireuberg in Lis Memoir ' Ueber ilen Griiusand uud seine Erlauterung des organiscben
Lebens/

Fig.

1. — Cast of tbe interior of a Nummuline sbell from
the Nummulitic Limestone of Traunstein, and
considered by Ehrenberg as representing a
new genus, to Mliicb be gives the name
Meso2iora.

2. — Cast of the interior of Orbitoides Fortisii (Prattii),
from the Nummulitic Limestone of Traunstein.

3. — Cast of a portion of the median layer of a
similar specimen, showing the connections of
its chambers and its annular canals.

4. — Cast of the central chambers of an organism
designated by Ehrenberg Orbitoides javanicus.

5. — Cast of two of the perijiheral chambers of the
same, showing their connections and the inter-
septal system of canals.

N.B. The ijroad bifurcating band by which
this figure is crossed pretty certainly represents

Fig.

the excavation of some parasitic plant or animal,

such as has made the irregular canals in fig. 2.

G. — Cast of two chambers of Nummidina striata, show-
ing the forms of their segments and the com-
munication between the canal-system of the
interseptal spaces and that of the marginal
cord.

7. — Cast of the interior of a Nummuline shell, desig-
nated by Ehrenberg Nonionina (?) bavarica, from
the Nummulitic Limestone, showing the forms
and connections of the chambers, and a portion
of the canal-system.

8. — Casts of (.v) Nodosaria, and (b) Vaginulinu, the
latter from the Zeuglodon (Nummulitic) Lime-
stone of Alabama.

<). — Cast of the interior of a Textularia {Gram-
mostomum, Ehr.) from the same.

PkteXXII.

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