" Spongiada(

I

•KR tf •

v CA'

THE

RAY SOCIETY

INSTITUTED MDCCCXLIV.

This volume is issued to the Subscribers to the BAY SOCIETY for

the Year 1864.

LONDON:

MDCCCLXIY.

6 1
A MONOGRAPH

OF THE

BRITISH SPONGIADJE,

B5

J. S. BOWERBANK, LL.D.,

F.K.S., F.L.Si, F.G.S., F.Z.S., F.H.A.S.,
MKUBJSK Of THE ENTOMOLOGICAL SOCIETY OF LONDON; OF THE MICROSCOPICAL SOCIETY

OF LONDON; CORRESPONDING MEMBER OF THE DUBLIN UNIVERSITY

ZOOLOGICAL AND BOTANICAL ASSOCIATION; OF THE PLYMOUTH INSTITUTION, AND
DEVON AND CORNWALL NATURAL HISTORY SOCIETY, ETC., ETC.

VOL. 1.

LONDON:

PUBLISHED FOR THE EAY SOCIETY BY
ROBERT HARDW1CKE, 192, PICCADILLY.

MUUCCLXIV.

FEINTED BT
J. E. ADLAED, BARTHOLOMEW CLOSE.

TO

PROFESSOR R. E. GRANT, M.D.,

F.R.S., F.K.S.E., F.L.S., F.G.S., F.Z.S., ETC.,

I'ROFESSOB OF COMPARATIVE ANATOMY AND ZOOLOGY IN UNIVERSITY COLLEGE, LONDON.

ETC., ETC.,

'ris M\\m is

AV1TH THE MOST SINCERE RESPECT
FOR HIS PROFOUND KNOWLEDGE OF NATURAL HISTORY IN GENERAL,

AND ESPECIALLY FOR THE LUCID AND ABLE MANNER
IN WHICH HE LED THE WAY IN THE SAME FIELD OF INVESTIGATION AS THAT

OF THE PRESENT WORK,

AND WITH MUCH GRATITUDE FOR THE KIND ADVICE

AND LIBERAL ASSISTANCE THE AUTHOR HAS RECEIVED FROM HIM

DURING THE COURSE OF ITS PREPARATION.

PREFACE,

IN treating a subject so new, and to a great extent so
obscure, as the ' History of the Spongiadae/ it may reason-
ably be deemed necessary that the author should explain to
his readers the origin and object of the work which he
presents to them.

The highly interesting and valuable researches of Pro-
fessor Grant in the unexplored field of their anatomy and
physiology published in the ' Wernerian Memoirs/ and in
the ' Edinburgh New Philosophical Journal/ and the labours
of Dr. Johnston, in collecting and identifying the species
described by numerous authors, ably concluded and pub-
lished in his ' History of British Sponges/ in 1842, natu-
rally created an interest in these singular creatures that had
never before been excited to so great an extent, and which
led naturalists to believe that a new and pleasing field of
investigation lay before them.

Impressed with these ideas, I made some desultorv

b

VI PREFACE.

observations on their structure, the publication of which
led to frequent communications with my late amiable and
talented friend, Dr. Johnston, who strongly urged me to
commence a more extended systematic investigation of the
structural peculiarities of exotic as well as of native species.
Thus stimulated, I commenced my investigation of their
anatomy, and speedily found in their structure so much
that was curious and beautiful, so many admirable mechani-
cal and physiological contrivances that I soon became deeply
interested in the subject.

The British sponges alone have afforded me a very exten-
sive series of new and beautiful forms of organization, and
as my knowledge of the number of the species and the peculi-
arities of their structure became extended, I quickly became
aware that the list of our native species contained represent-
atives of nearly every known genus of these animals, and
that such an extension of my investigation as that published
in the present volume became absolutely necessary to com-
plete the terminology not only of the British species already
described, but those also which the future researches of
naturalists may make known to us.

In the pursuit of this object I have done my best to
rescue the hidden Avonders and beauties of these extraordi-
nary creatures from comparative oblivion, and their exami-
nation and investigation have been for more than a quarter
of a century a continuous source of fresh pleasures and
surprises to me ; but, although in the course of these re-
searches I have examined a very large number of exotic as
well as of native species, I can assure my readers that I
have by no means exhausted the subject, and that a rich
field of pleasure still remains to be explored by future

PREFACE. Vll

naturalists who may be induced to pursue similar investi-
gations, and they will, I trust, find their labour facilitated by
the endeavours I have made to systematise the species, and
to construct a language of description by which their parts
may be known and described by future students of their
history. The necessity for this extension of my subject
beyond the limits of the British species, becomes the more
apparent when we consider that in the larger portion of
living creatures our knowledge of them may be greatly
facilitated by accurate figures of their external forms and
their colour, but we have this assistance to a very slight
extent with the Spongiadae. No two specimens of a
species agreeing precisely in form with each other, and
the discrepancies in shape arising from differences in
age, degree in development, and the varied influences of
locality, are such as to perfectly bewilder the student who
depends on external form as a means of recognition, and to
complete his confusion the variations of colour to which
many species are subject is almost as great in proportion as
that of external form. To these difficulties, perhaps, we
may in a great measure attribute the neglect with which
this branch of marine natural history has been treated, and
the slow progress that has been made in acquiring a know-
ledge of them, even by the most enlightened and philo-
sophical of the naturalists of the past and present centuries.
Their nature is also such as to present scarcely any at-
tractive feature to the curious student in zoology. No
animal motion, no functional demonstration is visible to the
eye of the casual observer to attract his attention from the
active and more beautiful tribes of marine animals amidst
which they are found, and it is only when we sit down
studiously to examine their anatomical structure by the aid
of a good microscope that we become aware of the ex.

Vlll PREFACE.

ceeding variety and beauty of their structure, and are
thence induced to investigate the living actions of organs
so numerous, varied, and beautiful as those displayed to us
by a careful examination of their structure. With these
difficulties surrounding ray earliest attempts at the recog-
nition of species, and with a rapidly increasing knowledge
of the variety and beauty of the tissues which presented
themselves, as I proceeded with my investigation I felt
the necessity of abandoning external form and colour as
descriptive characters, and determined patiently to work out
a series of descriptive characters based on the peculiarities
of anatomical structure, and thus it is that in accordance
with the necessities of this preliminary labour, the introduc-
tion to the history of the British species has become di-
lated into an attempt at a general history of the anatomy
and physiology of the whole of the Spongiadae.

The accomplishment of this task would have been com-
paratively hopeless without the very kind and liberal assist-
ance of numerous friends

To the late Dr. Ayres, of the Mauritius, I am indebted
for a very interesting collection of sponges from that
locality ; and to Mr. Joshua Alder, of Newcastle-upon-
Tyne, for frequent contributions of British species. The
late Professor Bailey, of New York, kindly supplied me
with specimens of Spongilla from North America. To
Mr. H. W. Bates I am indebted for my knowledge of some
of the most interesting species of the Spongillidae of the
river Amazon ; and Mr. J. Spence Bate I have to thank
for the loan of many interesting species of British sponges.
To my late friend, Mr. G. Barlee, I am deeply indebted
for repeated collections of British species of sponges from

PREFACE. IX

the Orkneys and Shetlands, containing the types of some of
the most interesting of onr native species. To Mrs. Brett,
of Tenby, I have in like manner to return my best thanks
for repeated contributions of new and interesting species ;
and I am also greatly indebted to my friend Mr. Bean, of
Scarborough, who has, with his accustomed kindness and
liberality, contributed numerous specimens to my cabinet,
and has placed the whole of his rich collection of sponges
at my service for examination and description. I am also
greatly obliged to the late Mrs. Dr. Buckland for many
interesting specimens collected by her at Sark and Guernsey.
Mv late friends, Mr. Robert Brown and Mr. Lucas Barrett,

V

have also favoured me with valuable contributions of speci-
mens. I have also to thank Dr. Battersby, of Torquay, for
similar kind assistance. To Mr. H. J. Carter, late of
Bombay, I am greatly indebted for an abundant supply of
the species of Spongilla so ably described by him in the
' Journal of the Bombay Branch of the Royal Asiatic
Society/ No. XII, 1849, and for an interesting collection
of sponges from the neighbourhood of Aden. To my
friend Mr. George Clifton, late of Freemantle, Western
Australia, I am especially grateful, for the numerous and
large collection of the sponges of that locality with which
he has favoured me, through which, from their fine state
of preservation, I have obtained many beautiful varieties
of organization that I was before unacquainted with. To
Mrs. Collings, the lady of the Seigneur of Sark, I have also
to return my best thanks for much kind information and
assistance regarding the marine productions of the Channel
Islands. Mr. Hugh Cuming has also my best thanks for
having assisted me in obtaining many interesting specimens,
and especially for the kind and liberal use he has allowed
me of his beautiful specimen of Eupleddla asperyillum,

X PREFACE.

Owen. Professor Dickie, of Aberdeen, has also kindly
allowed me the nse of his valuable collection of northern
specimens of sponges. To my friend Mr. Dunsterville, of
Algoa Bay, I am indebted for a fine collection of the
sponges of that locality ; and to Mr. H. Deane, of Clapham,
for rare specimens of Spongilla from India. I have to
thank Professor Milne Edwards, of Paris, for much kind
assistance during my visits to the museum of the Jardin des
Plantes ; and also my friend Dr. A. Farre, for the liberal use
he has allowed me of his fine specimens of Farrea occa and
Euplectella cucumer, Owen ; nor must I forget my late friend,
Professor Edward Forbes, who kindly supplied me with seve-
ral rare species of British sponges. To my friend Professor
Grant I am, indeed, deeply indebted, especially for the use
of the type specimens of British species described by the late
Colonel Montagu, and those presented to him by the late
Dr. Fleming, and also of specimens of those species which
he had himself described, by the means of which I have
been enabled to recognise many species described by the
authors mentioned above, and also by Dr. Johnston, the
identity of which must otherwise have remained in much
doubt and uncertainty. To my late friend, Mrs. Griffiths,
of Torquay, and to the Rev. Walter Gregor, of Aberdeen,
I am equally indebted for numerous interesting species
collected in the neighbourhood of Torbay, and Macduff in
Banffshire. My best thanks are also due to Dr. Davvson,
of McGilTs College, Montreal, for several contributions of
North American marine sponges, and for specimens also of
Spongilla from the river St. Lawrence. Dr. Asa Gray, of
Boston, and Dr. J. Leidey, of Philadelphia, United States,
I have to thank for specimens of North American Spongillas,
and Mr. J. K. Lord, for the loan of similar specimens from
Vancouver's Island.

PREFACE. XI

To my friend, Dr. Leared, I am much indebted for some
valuable and highly interesting specimens of the sponges
of commerce, in the condition in which they came from the
sea, and for a collection of marine sponges from the shores
of Iceland. To Dr. Lister, of Madeira, and to my friend,
Mr. J. J. Lister, of London, my thanks are also due for
donations of marine sponges. Professor Harvey, of Trinity
College, Dublin, has also favoured me with some interesting
specimens of sponges from Australia. To my friend Mr.
James Hilton, I am indebted for several new and interesting
forms of sponge spicula from the Indian Ocean, and to Mr.
George Hyndman, of Belfast, for many interesting species
from Belfast Lough, and other Irish localities. My late
friend, Commander Ince, R. N., favoured me with a collection
of sponges from the Chinese seas and other localities. To Mr.
J. Yate Johnson, of Madeira, I am much indebted for sponges
containing several new and very interesting forms of spicula
and organization, which are figured in this work, and also to
my late friend Dr. Johnston, of Berwick-on-Tvvecd, for nu-
merous acts of kindness, and for many interesting specimens
of West Indian sponges. My late friend Mr. Thomas
I n gall, contributed largely to my knowledge of new forms
of spicula and other organs of the Spongiadae by numerous
donations of interesting species, and by placing the whole
of his extensive collection of sponges and of microscopic
objects illustrative of their structure at my service for exami-
nation. My late friend, Mr. Rupert Kirk, of Sydney,
kindly supplied me with a large collection of sponges from
Wollongong, near Sydney, and his son, Mr. Richard Kirk,
a similar collection from Port Fairey. My best thanks are
also due to Mr. Robert McAndrew, for numerous specimens
of British species, and for several highly interesting and
valuable sponges from the Coast of Norway, the structures

Xil PREFACE.

from which are figured in this volume. My friend, the
Rev. A. M. Norman, of Sedgefield, near Ferrybridge,
Durham, has largely contributed to the list of new
British species, which will be published in the second
volume of this work, by having with the greatest liberality
and kindness, continually placed the results of his
numerous dredging excursions at my disposal for exami-
nation.

My indefatigable friend, Mr. C. W. Peach, of Wick,
N.B., has also continually and frequently favoured me with
numerous northern species ; and to my friend, Mr. Robert
Patterson, of Belfast ; my late friend Mr. William Thomp-
son of the same locality, and to Mr. William Thompson of
Weyrnouth, I am similarly indebted. My late friend Mr. S. P.
Pratt, favoured me with a collection of East Indian sponges,
from which several highly interesting types of beautiful forms
of organization have been figured in this volume. My friend
Captain Thomas, R.N., of the Hydrographical Survey, has
also assisted me greatly with numerous interesting speci-
mens acquired in the course of his professional avocations.
To my late friends, Professor John Quekett and Mr. J.
H. Stewart, of the Royal College of Surgeons, I am under
great obligations for numerous kind acts and many valuable
specimens of organization, and I am also much indebted to
my friend Mr. Charles Tyler, for much valuable assistance
in the examination of exotic sponges in search of new forms
of organization. In addition to the above I must also tender
my thanks to Professor Ansted, Professor King, of Galway,
Mr. N. H. Mason, Mr. J. Gwyn Jeffreys, Mr. Howes, of
Newcastle, Mr. Tumanowicz, Mr. Vickers, of Dublin, and
Mr. C. M. Topping, for their kind donations of specimens.
To my friend, Mr. William Ferguson, of Burton-on-Trent, I

PREFACE. Xlll

am also indebted for much kind classical assistance in the
preparation of the nomenclature.

And lastly, I must not omit expressing my acknow-
ledgements to Mr. W. Lens Aldous, for the exceedingly
accurate and beautiful delineations, by the aid of the micro-
scope and camera-lucida, of the delicate and frequently com-
plex tissues which illustrate this work.

I fear that, in the performance of this agreeable duty of
thanks to the numerous friends who have so generously
assisted me, I may have inadvertently omitted the mention
of some who have favoured me with specimens or other
assistance, but to those I have named, and to all who have
contributed either information or specimens, 1 beg to pre-
sent my most sincere thanks.

CONTENTS.

ANATOMY AND PHYSIOLOGY OF THE SPONGIAD.E.

PAGE

PllEFACE . . i

OROANO GRAPH Y . 1

The Spicula . . 5

The Essential Skeleton Spicula . . 13

Auxiliary Spicula . 16

Connecting Spicula . . 16

Prehensile Spicula . . 20

Defensive Spicula . 21

Internal Defensive Spicula . . 28

Spicula of the Membranes . .39

Tension Spicula . 39

Eetentive Spicula . . 42

Anchorate Spicula . . 45

Spicula of the Sarcode . 50

Simple Stellate Spicula . . . .51

Compound Stellate Spicula . 52

Spicula of the Ovaria and Geminules . . 57

Keratode . . 62

XVI CONTENTS.

PAGE

Membranous Tissues . . . .66

Fibrous Structures . 68

Primitive Fibrous Tissues . . .68

Keratose Fibrous Tissues . . 71

Solid Simple Keratose Fibre . 72

Spiculated Keratose Fibre . . 73

Hetro-spiculated Keratose Fibre . . 74

Multi-spiculated Keratose Fibre 75

Inequi-spiculated Keratose Fibre . . .75

Simple Fistulose Keratose Fibre . 75

Compound Fistulose Keratose Fibre . 76

Eegular Arenated Keratose Fibre . 77

Irregular Arenated Keratose Fibre . . 78

Siliceous Fibre . 78

Prehensile Fibres . . . .80

Cellular Tissue . ..81

ORGANIZATION AND PHYSIOLOGY . 83

The Skeleton . . 84

Sarcode ... .88

The Sarcodous System 90

The Interstitial Canals and Cavities . 97

Intel-marginal Cavities . . 100

Dermal Membrane . 106

The Pores . 109

The Oscula . . .112

Inhalation and Exhalation . .113

Nutrition . .121

The Cilia and Ciliary Action . 128

Eeproduction . . 132

Gemmules . » . 144

External Gemmulation . . 149

Propagation by Sarcodous Division . . 149

Growth^and Development of Sponges . 152

CONTENTS. xvu

PAGE

ON THE CLASSIFICATION OF THE SPONGIAD^E . . 158

On the Generic Characters of the Spougiadie . 156

Tabular View of Systematic Arrangement . . 159

Order 1. CALCAEEA . . . 160

Grantia . . . .162

Leucosolenia . . . 164

Leuconia . 161

Leucogypsia ... . 165

Order 2. SILICEA . 166

Geodia . 167

Pachymatisma . . 171

Ecionemia . .173

Alcyoncellum . .174

Polymastia . . . 177

Halyphysema . .179

Ciocalypta . . 179

Tethea . .181

Halicnemia . . 184

Dictyocylindrus . 185

Phakellia . 186

Microciona . . . 188

Hymeraphia . . 189

Hyrnedesmia . . 190

Hymeniacidon . . 191

Halichondria . 195

Hyalonenia . . 195

Isodictya 197

Spongilla . 199

Desmacidon . 200

Eaphyrus . 201

Diplodemia . . 201

Dactylocalyx . . 203

Farrea 204

XV111 CONTENTS.

PAGE

Order 3. KERATOSA . . . . 205

Spongia ..... 205

Spongionella . . . . 200

Halispongia . . . 207

Chalina . ... 208

Verongia ..... 209

Auliskia . . . 210

Stematumenia .... 211

ON THE DISCRIMINATION or THE SPECIES OF THE SPONGIAD^; 212

The Spicula . .213

The Oscula . . 215

The Pores . 216

The Dermal Membrane . . 216

The Skeleton . . 217

The Interstitial Membranes . .218

The Intermarginal Cavities . . 218

The Interstitial Canals and Cavities . .219

The Cloacal Cavities . .219

The Barcode . . . 220

The Ovaria and Gemmules . . .221

ON THE PRESERVATION OF THE SpONGIAD^ . . . 225

TERMINOLOGY, AND DESCRIPTIONS OF THE ILLUSTRATIVE

FIGURES . . 228

Spicula of the Skeleton . . .229

Connecting Spicula . . . 234

Prehensile Spicula . . 237

Defensive Spicula . . 237

Spicula of the Membranes . . 243

Tension Spicula . . . 243

Retentive Spicula . . . . 246

Compound Stellate Spicula . . . 257

Spicula of Ovaries and Gemmules . 262

CONTENTS. XIX

PAGE

Elongate Spicula . . 262

Birotulate and Boletiform Spicula . 264

New forms of Spicula . . . 267

Spicula the position of which is unknown . 269
Membranous Tissues . . .271

Fibrous Structures .... 272

Keratose Fibrous Tissue . 272

Prehensile Fibre .... 274

Fibrilated „ . 274

Cellular Tissue . . . 274

Sarcode . . . . 275

Internal and External Defences . . 275

Intermarginal Cavities . . . 277

Cilia and Ciliary Action . . . 279

Eeproductive Organs . . . 279

ILLUSTBATIONS or THE GENERA . . . 283

Order 1. CALCAEEA ... . 283

Grantia, Leucosolenia, Leuconia, Leucogypsia . 283

Order 2. SILICEA . . . 284

Suborder 1 . . 284

Geodia, Pachymatisma, Ecionemia, Alcyoncellum . 284
Polymastia, Halyphysema, Ciocalypta, Tethea,

Halicnemia . . . 285
Dictyocylindrus, Phakellia, Microciona, Hyme-

raphia . . . 286

Hymedesmia .... 287

Suborder 2 . . .287

Hymeniacidon . . . 287

Suborder 3 . . .287

Halichondria, Hyalouema, Isodictya, Spongilla . 287

XX CONTENTS.

PAGE

Suborder 4 . . .288

Desmacidon, Raphyrus . . 288

Suborder 5 . . .288

Diplodernia .... 288

Suborder 6 . . . . 288

Dactylocalyx . 288

Suborder! . . 288

Farrea . . 288

Order 3. KEEATOSA . . 288

Suborder 1 . .288

Spongia . 288

Spongionella . 289

Suborder 2 . . 289

Halispougia .... 289

SuborderZ .... .289

Chalina . .289

Suborder 4 . . 289

Verougia . .289

Suborder 5 . . 289

Auliskia . . 289

Suborder 6 ... .289

Stematumenia . .289

Suborder 7 . .289

Dysidea . . 289

ON

THE ANATOMY AND PHYSIOLOGY

OF THE

SPONGIAD^l.

I. ORGA.NOGRAPHY.

NATURALISTS are deeply indebted to Dr. Johnston for
having, with great labour and patient research, collected to-
gether all the widely scattered information that existed on
the subject of the Spongiadae, and for having, with so much
sound judgment, reduced the comparative chaos of facts
and opinions regarding them to such a condition of order
as to greatly facilitate the labours of succeeding students.
He has displayed in the three introductory chapters to his
c History of British Sponges ' such an extent of reading
and research, from the earliest writers on natural history
to the latest authorities on those subjects, such an admirable
and lucid condensation of the information he has thus
obtained, as to render them one of the most valuable and
satisfactory treatises on this obscure branch of natural
history that has hitherto been written. It would, therefore,
be a work of supererogation on my part to endeavour to
dilate on that portion of our subject, and I am satisfied that
I cannot do better than to recommend to students in this
branch of natural history the careful perusal of his intro-

2 ANATOMY AND PHYSIOLOGY

duction to the study of the Spongiadse, as an excellent
preparation for the investigation of the British species.

From the researches of Dr. Johnston, detailed in Chapter
III, " The Discovery of British Species," it appears that the
first British sponge recorded was by Mathias de FObel, in
1616. Ellis, in his 'History of British Corallines/ 1755,
described two species, and in his ' Zoophytes/ 1786, edited
by Solander, the number is increased to seven ; other spe-
cies were described by Professor Jameson and Mr. James
Sowerby ; and, in 1 809 fifteen indigenous species were
known. In 1812 Colonel Montagu extended the number
to thirty -nine, and in 1852 Dr. Johnston further in-
creased the number to fifty-six. But from these we must
deduct eleven, which are only repetitions under new names,
or, otherwise, no species ; reducing the correct number of
species known to forty-five.

In endeavouring to verify these species, I found, appa-
rently, insuperable difficulties arising from the exceedingly
unsatisfactory condition of the descriptive language em-
ployed by preceding authors, while, at the same time, I was
struck by the abundance of excellent characters that were
to be derived from the structural peculiarities of the ani-
mals. Up to the present time the Spongiadae have been
classified either by their external form or in accordance
with their chemical constituents. In the second edition of
Lamarck's 'Anim. s. Vert./ 138 species are included in
the genus Spongia, without the slightest reference to their
internal structure ; and they are divided into seven groups
by external form only, the same characters serving also, in
a great degree, to discriminate the species.

Fleming, Grant, Johnston, and other modern naturalists,
have made their principal divisions depend on their che-
mical constituents, and have therefore constructed three
great divisions as genera : — Spongia, composed of keratose
fibres unmixed, as it was supposed, with earthy matter ;
Halichondria, formed principally of siliceous spicuJa ; and
Grantia, having the skeleton composed of calcareous spicula.
Included in the second of these divisions are the genera
Tetliea, Geodia, Pachymatisma, Spongilla, Dysidea, and

OF THE SPONGIAD^E. 3

Halisarca, and these nine genera are all that are contained
in Dr. Johnston's ' History of British Sponges.'

Both of these arrangements are very insufficient, and
that of Lamarck completely ineffectual, inasmuch as there
is no class of animals in which the form varies to so great
an extent, according to the difference of locality or other
circumstances; and also even when there is a striking
normal form, it is rarely thoroughly developed until the
animal has reached its full maturity. According to the
practice of Lamarck, even under the most favorable cir-
cumstances there are frequently recurring difficulties in the
determination of the species by this method, as the same
forms are found to be common to a great number of
sponges, the internal organization of which are widely
different to each other. Prom these causes it is, that no
naturalists with whom I have conferred on this subject
have been able to determine with certainty the species of a
sponge by the description given by Lamarck in his ' Anim.
s. Vert./ or by those of any other author who has adopted
the same method of description, with the exception of, per-
haps, a few very striking species.

The division of the Spongiadac by their chemical consti-
tuents may serve very well to separate them into primary
groups, but they are far too limited to be applied as generic
characters. I have therefore for this purpose rejected both
systems, and have retained the latter one for the purpose of
forming primary divisions only, and I purpose founding
the generic characters principally on the organic structure
and mode of arrangement of the skeleton. Spongilla differs
in no respect from Halichondria, as now accepted by natu-
ralists ; and the latter, even in the narrow circle of the list
of British species, contains at least ten distinct modes of
arrangement of the skeleton, each of which is constant and
well defined in its character.

It is not my intention to propose the rejection of any of
the well-established genera of my predecessors, but to con-
fine each genus strictly within the bounds indicated by the
peculiar mode of the structure of the skeleton which exists
in that species of sponge which is the oldest-established

4 ANATOMY AND PHYSIOLOGY

and best-known type of the genus, and to refer all others
that may distinctly differ from that type to new genera
founded on structural principles.

When I commenced in a similar manner a critical exa-
mination of the specific characters of preceding authors,
and endeavoured to collect and classify them, I found them
to l)e still more indeterminate than those of class or genera ;
in truth, it appeared that there was scarcely an approach to
a distinct terminology to the science, and that the same
author frequently designated the same organ, under dif-
ferent circumstances, by a totally different name ; I there-
fore felt it absolutely necessary, before proceeding to the
description of new species, to enter into a thorough syste-
matic examination of the organization of the whole of the
species within my reach, and to characterise the organs in
such a manner as to render the terms I applied to them
definite in their meaning and limited in their application ;
and in pursuing this object I quickly found an abundance
of constant and well-characterised forms and combinations
of organization, capable of being applied with precision to
the purposes of generic and specific descriptions.

I propose, therefore, in the first instance, to characterise
the elementary tissues in the following order :

1. Spicula.

2. Keratode or horny substance.

3. Membranous tissues.

4. Fibrous tissues.

5. Cellular tissues.

And, in the second place, to treat of the organization
and physiology in the following order :

1. The skeleton.

2. The sarcodous system.

3. The interstitial canals.

4. Intermarginal cavities.

5. Dermal membrane.

6. The pores.

7. The oscula.

OF THE SPONGIAD^E. 5

8. Inhalation and exhalation.

9. Nutrition.

10. Cilia and ciliary action.

11. Reproduction, ovaries, gemmules, &c.

And to conclude with observations on

The generic characters ;
The specific characters ; and
On the method of examination.

In my references to the views of preceding writers
regarding the anatomy and physiology of the Spongiada3,
I shall endeavour to correct the errors, rather than to point
out the authors of them, feeling satisfied that posterity will
care as little about the petty angry discussions concerning
the facts and opinions of the present period as we do about
those of our ancestors ; at the same time I shall endeavour
to do justice to the industry and research of preceding
naturalists, whose errors of omission are entitled to every
possible excuse, when we remember the difficulties they
laboured under in the course of their investigations, for
want of competent microscopic powers with which to work
out the organization of the minute and delicate objects of
their research, while we are in full possession of all the
advantages of the modern improvements of the microscope,
giving a pleasure and facility to our investigations that
must have been comparatively almost unknown to our
predecessors.

THE SPICULA.

The spicula are essentially different in character from the
fibres of the sponge, although the latter may be equally
siliceous with the former. However closely the spicula may
be brought into contact with each other or with siliceous
fibre, they do not appear to unite or anastomose, while the
fibre, whether siliceous or keratose, always anastomoses
when it comes in contact with other parts of its own body
or of those of its own species.

6 ANATOMY AND PHYSIOLOGY

111 the early stage of their development the spicula
appear to consist of a double membrane, between which
the first layer of silex is secreted, and in this condition they
present an internal cavity approaching very nearly to the
size of their external diameter. In this state they readily
bend abruptly in any direction without breaking, as may be
seen in Pig. 247, Plate XI, which represents a porrecto-
ternate spiculum from the termination of one of the radial
lines of the skeleton at the surface of Tetkea cranium.
This spiculum has been considerably distorted by pressure
on the points of the rays at its apex. The deposit of the
silex is not continuous and homogeneous, but is produced
in successive concentric layers, which it would appear are,
at least for a period, equally secreted by the inner surface
of the outer membrane and the outer surface of the inner
one ; for we always find that as the development of the
spiculum progresses, the internal cavity gradually becomes
less, until finally it exists only as a central canal of very
minute diameter in comparison with that of the spiculum
itself. These stages of development may often be seen in
the spicula of young specimens of Spongilla fluviatilis,
especially in the spring, when they are growing rapidly. If
small fragments of the sponge be slightly charred in the
flame of a lamp, and then submitted to microscopical ex-
amination, the outer and inner membranes of the spicula
will readily be rendered visible (Figs. 248, 249, Plate XI) ;
in immature spicula the internal membrane is represented by
a dense black film of charcoal, as in Pig. 249, Plate XI ;
while in the mature ones the small central cavity is seen to
be lined by so thin a membrane as to afford by its charring
a slight brown tinge only to its walls (Pig. 248, Plate
XI). The concentric deposition of the layers of silex or
carbonate of lime in the spicula are also readily to be
seen (Pig. 250, Plate XI) in transverse fractures of almost
any large spiculum, either siliceous or calcareous, and they
present the same aspect as similar sections of either the pris-
matic cells of shell tissue or the spicula of a Gorgonia. The
amount of silex, and the manner of its deposition in the
spicula, is not the same under all circumstances. Where

OF THE SPONGIAD^E. 7

the spiculum is simply required to give strength and firm-
ness to the skeleton, as in the greater number of the
Halichondraceous sponges, the whole interior of the spiculum
becomes rapidly filled with silex ; but where strength is
required to be combined with great elasticity and tough-
ness, the mode of deposit is especially adapted to the
requirements of the occasion ; the amount of the silex
deposited is small, and confined wholly to the surface, while
the interior appears to be filled with keratode. These laws
of deposit will perhaps be best illustrated by my detailing
a series of experiments I made by the incineration of the
spicula of various sponges in the flame of a small spirit-
lamp. I was led to this series of experiments by frequently
observing during the course of my investigations the great
amount of flexure that many of the large and long spicula
would sustain without fracture, and the perfect elasticity
with which they regained their original form and position.
Thus, in mounting the spicula of Tetliea cranium in Canada
balsam, the long and slender porrecto-ternate defensive
spicula projected from its surface would frequently have the
shaft bent in a series of sigmoid curves or even loops ; and
the thickest portion of the same spicula, while in their
natural condition, may be bent down to the surface of the
sponge, from which they spring at right angles, so as to
form an arc of the third of a circle with perfect impunity.
This great flexibility appeared to me to be so incompatible
with a purely siliceous structure, that I determined to select
the spicula of Tetliea cranium, more especially to work out
this problem, and from the large size of those of the
skeleton fasciculi they are more than usually favorable for
the purpose. If we view these spicula in their natural
condition, mounted in either water or Canada balsam, by
transmitted light and a linear power of 150, they present
all the usual appearances of solid siliceous spicula ; there is
a small central tubular cavity, and the substance of the
spicula intervening between it and the external surface
presents to the eye the linear appearance that characterises
a deposit in concentric circles ; and the fractured ends have
precisely the same aspect that filaments of the same size of

8 ANATOMY AND PHYSIOLOGY

hard dry glue or glass would present to the eye. If these
spicula be now burned in the flame of a small spirit-lamp
until the combustion is completed and the mass is brought
to a white heat, and it be then examined as before, the
results are widely different in their aspect ; the spicula have
become considerably increased in diameter, and instead of
being solid, they are now extremely thin tubes of silex, lined
with a dense and nearly opake film of charcoal, rough and
granulated in its appearance. I thought in the first instance
that I might have unwittingly selected a fasciculus of young
spicula only, for burning, and I therefore repeated the
experiment, burning only half of the fasciculus and pre-
serving the remainder in an unaltered condition ; and on
carefully mounting the specimen in Canada balsam, I found
the same results precisely ; the unburned half of the
fasciculus presented all the characters of solidity that I
have before described, while the burned half was in perfect
unison with the previous results of incineration ; and at
the junction of the two, the transition from the one state to
the other might be readily traced even in single spicula. The
external coat of silex in these spicula is so thin and the coat
of charcoal with which it is lined so rough and opaque, that
the thickness of the silex cannot be readily ascertained ;
but in one of the short, stout, fusiformi-acerate spicula of
the dermal coat of the sponge, which is about the same
diameter as that of the skeleton spicula, I succeeded in
measuring the thickness of the siliceous coat accurately after
incineration. The length of the spiculum was ^th of an
inch, the greatest diameter ^th of an inch, and the thick-
ness of external siliceous case ^cth of an inch. Figs.
251 and 252, Plate XI, represent portions of two of the
large spicula of the skeleton after incineration.

I have very little doubt that the combustible matter in
the interior of these large spicula is really keratode, one of
the most elastic and durable animal substances with which
we are acquainted. The mode of its deposition within
these organs is precisely the same with that presented in
all the varieties of keratose fibre with which I am ac-
quainted ; and from its concentric arrangement, the nature

OF THE SPONGIAD.E. 9

of the material itself, and its combination with a thin
external case of silex, it presents perhaps one of the most
admirable natural combinations of strength, elasticity, and
durability.

The structure which I have described as prevailing in
Tetliea cranium is not peculiar to that genus. I obtained
similar results from the incineration of the spicula of Geodia
M'Andrewii, Bowerbank, MS., a new and remarkably in-
teresting species. In this sponge there appeared to be a
greater amount of silex secreted in the large skeleton
spicula than in Tethea ; while some of them after incinera-
tion were resolved into thin shells of silex, others withstood
the operation and retained their form ; and some were so
completely siliceous that, on plunging them into the drop
of water for examination while red-hot from the flame of the
lamp, the result was the same as if they had been solid
glass rods, and these were cracked and shattered in every
direction (Fig. 254, Plate XI).

I submitted to the same mode of incineration a few of
the long siliceous spicula or fibres of Euphctclla aspergillum,
Owen, burning about half of each fibre, and the result,
although somewhat different, was equally satisfactory. The
unburned portion appeared perfectly solid, but exhibited
the usual trace of concentric structure. The end thoroughly
burned became reduced to a thin filament of densely black
matter like charcoal, but the junction of the burned and
unburned portions were extremely interesting. At this
point the action of the heat upon the concentric layers had
separated them from each other in the form of a series of
thin curved flakes or coats, illustrating the concentric
structure in a very satisfactory manner ; demonstrating that
the outer coat of siliceous matter was not the only one, and
that probably there were several coats, each containing a
sufficient amount of silex in its composition to resist
disintegration by incineration (Fig. 253, Plate XI).

On operating in like manner on the spicula of Chalina
oculata, Bowerbank, little or no alteration was perceptible
in the spicula, the inner cavity remaining the same as in
the imburned ones, and distinguished only by a slight

10 ANATOMY AND PHYSIOLOGY

brown tint, indicating the existence of but a very small
amount of animal matter within. This result might be
expected ; the spicula, being imbedded in the keratose fibre
to give it additional firmness and strength, are not required
to be elastic ; they are therefore short, comparatively stout,
and solid in their structure.

A specimen of Halickondria panicea, Johnston, burned
in the flame of a spirit-lamp to a white heat, exhibited no
alteration in the mature spicula, in many of which I could
not detect a central tubular cavity ; and I presume in these
cases the spicula were entirely filled with silex, as in
younger spicula it was more or less apparent. When the
cavity was very small, the colour had a very faint tinge of
brown, and, as in other cases, when the cavity increased in
diameter, the amount of colouring matter produced by the
incineration of the animal matter within became greater
and deeper in its tint, until in the young and immature
spicula the internal cavity occupied the greater part of its
diameter, and it became perfectly black and opaque; and in
one spiculum the gaseous matter generated within expanded
one part of the spiculum to such an extent as to cause it
to resemble exactly a hydrometer in form.

The result of the incineration of HalicJtGndria incrustans,
Johnston, was very similar to that of Hal. panicea. The
adult spicula remained unaltered, and the central canal was
rendered more apparent than it was before.

On burning portions of Sponyilla Jluviatilis and lacuslris,
Johnston, and of Spongilla cerebellata, Bowerbank, I found
the results were similar to those obtained from Halickondria
panicea and incrustans, as regards the spicula of the
skeleton ; but in the small spinous spicula investing the
ovaria of the last-named species there was no apparent
alteration, nor could any indication of a central cavity be
seen .

The calcareous spicula of Grantia compressa withstood
incineration better than I expected. The surface was studded
with numerous little vesicles, generated by the heat, and
which interfered with their transparency ; but they re-
tained nearly their original colour and proportions, and it

OF THE SPONGIAD^E. 11

may therefore be concluded that they contained so great a
proportion of calcareous matter as to prevent their disin-
tegration by heat.

Many of the forms of the spicula are by no means
peculiar to the Spongiadse ; but, on the contrary, as I shall
hereafter show, their types are frequently to be found in the
more highly organized classes of animals, and especially
among the Zoophyta, the Tunicata, and the Nudibranchiate
Mollusca. They are always of an organic type, never
crystalline or angular.

Each of the elongated forms of spicula may be said to
be composed of three parts, the base, the apex, and the
shaft intervening between the two ; and, generally speaking
these parts may be readily determined, even when the
spicula are isolated.

Each species of sponge has not one form of spiculum
only, equally dispersed throughout its whole substance ;
but, on the contrary, we find that separate parts have each
its appropriate form ; and thus we find that three, four, or
even more forms often occur in the same individual ; and
in Tctkea cranium there are no less than seven distinct
shapes. But these differences in structure must not lead
us to believe that every strange form of spiculum that meets
the eye is a normal one ; remarkable variations are often
produced for especial purposes in the construction of the
skeleton or for other objects ; and in some species, Sjwngilla
lacustris, for example, the number of malformations that
are occasionally found is very remarkable. The size also of
the normal forms of spicula will often vary to a considerable
extent in the same sponge ; but if adult, they are always in
accordance with the type form, and if not adult, inter-
mediate states of growth are generally present to assist us
to form correct conclusions regarding them. The forms
thus appropriated to the different parts of the sponge are
not always peculiar to certain species, but, on the contrary,
they are frequently found to be repeated in other species
differing widely in their construction.

The spicula thus appropriate to particular parts of the
sponge are uniform in their general characters throughout

12 ANATOMY AND PHYSIOLOGY

the whole of the Spongiadae, and a great portion of them,
when adult, are so well characterised by their form as to
enable the student, when once well acquainted with their
peculiarities, to assign each readily to its proper place in the
sponge. In many cases they preserve the same form from
the earliest to the latest period of their development, while
in others the variations they undergo during their growth
are very remarkable. It is therefore necessary that these
mutations of form should be carefully noted whenever they
are observed, lest they be mistaken for normal ones.
Some of the most remarkable changes in form, during the
course of their development, will be described under their
respective heads.

The spicula in the skeletons of the Spongiadae appear to
be the homologues of the earthy deposits in the bony
structures of the more perfectly developed living forms.
In the higher tribes of animals we find the disintegrated
condition of the earthly deposits in the first stages of the
development of the bony structures in the form of minute
radiating patches, which in a more advanced stage unite
and form the solid mass of bone, as in the mammalian
tribes of animals, while in the cartilaginous tribe of fishes
these radiating centres of bony secretion never attain a
higher degree of development, but remain isolated points of
bony structure during the whole of the life of the animal.
And in the compound tunicated animals we find the cal-
careous stellate and sphero-granulate forms of spicula
developed in close accordance with the similar siliceous
forms in various species of sponges. Thus the stellate and
cylindro-stellate spicula of the sarcode in the Spongiadae
are apparently the homologues of the bony centres of
development in the higher animals. It is so likewise with
the other forms of sponge spicula. We find isolated
calcareous spicula of an irregular fusiformi-acerate shape,
representing the bony skeleton of the higher animals in
the outer integuments of several species of Doris.

Messrs. Alder and Hancock, in their admirable ' History
of the British Nudibranchiate Mollusca/ describe calcareous
spicula occurring in Doris aspera, bilamellata, and Triopa

OF THE SPONGIAD^E. 13

claviger, which appear to be analogous to the rectangulated-
triradiate spicula of Grantia; and they also state that in
the first-named species crucial or dagger-shaped spicula
occur in the branchiae and margins of the cloak of the
animal, and forms very similar to those occur on the inter-
stitial membrane o^Leuconia nivea, Bowerbank. Numerous
forms of tuberculated and smooth calcareous spicula are also
found in the extensive family of the Gorgoniadse. And the
siliceous simple bihamate form of retentive spiculum, so
abundant on the interstitial membranes of many species of
sponges, are closely represented by the calcareous bihamate
spicula so numerous on the tubular suckers of Echinus
sphfsra. Thus we find in the spicula only, a series of links
in the chain of animal development, intimately connecting
the Spongiadse with the higher tribes of animals.

In the solid siliceous fibres of Dadylocalyx (Pig. 274,
Plate XV), and in the tubular siliceous fibres of Farrea occa,
Bowerbank, MS. (Fig. 277, Plate XV), and especially in
the latter, we obtain a very much closer approximation to the
tubular forms of the bones of the higher classes of animals.

From our knowledge of the great scheme of the natural
development of animal life, the most perfectly organized
sponges appear to be those which secrete carbonate of lime
as the earthly basis of their skeletons, and the least perfect
those which secrete no earthy matter in the skeletons ;
those which secrete silex taking an intermediate position ;
but it must also be remembered that there is no form of
spiculum found among the calcareous sponges, or in the
higher tribes of animal life, that is not repeated among the
siliceous forms of spicula of the Spongiadae.

The spicula may be conveniently classed under the fol-
lowing heads :

1. The essential skeleton spicula.

2. The auxiliary spicula.

The Essential Skeleton Spicula.

In the siliceous sponges they are usually simple, elongate
in form, slightly curved, and occasionally more or less fur-

14 ANATOMY AND PHYSIOLOGY

nislied with spines. They are either irregularly matted
together, collected in fasciculi, or dispersed within or upon
the keratose fibres of which the skeleton is to a great extent
composed. Occasionally, but not frequently, they assume the
triradiate form. In the calcareous sponges, beside the simple
elongate form, the triradiate spicula are found in abundance.

All the elongate forms of spicula of the skeleton are sub-
ject to extreme variety in length. In some species they
maintain a great degree of uniformity, while in others they
vary to a very considerable extent, according to the neces-
sities arising from the mode of the construction of the ske-
leton. When the areas of the reticulations are large, they
are generally long and rather stout, and are usually shorter
when the proportions of the network are small and close.
When enclosed in keratose fibre, they are most frequently
smaller and shorter in their proportions than those in the
Halichondroid sponges. And in those species in which
they are dispersed over the membranous tissues, as in
Hymeniacidon, Bowerbank, they are generally long, slender,
and frequently flexuous. In the sponges of this structure
having siliceous spicula the triradiate form of spiculum
occurs but rarely, while in the calcareous sponges, which
consist of membranes and dispersed spicula, the triradiate
forms of skeleton spicula are the normal ones.

When the skeleton is constructed of large fasciculi of
spicula, as in Tetliea and Geodia, they attain their greatest
dimensions as essential spicula of the skeleton, frequently
exceeding the eighth of an inch in length.

The greatest known length of spicula occurs in the pre-
hensile ones of Euplectella asperf/illum and cucumer, Owen,
where they are found to exceed three inches in length ; and
in HyaloRema mirabilis, Gray, where in the spiral column
of the great cloacal appendage they reach the extreme di-
mensions of six or seven inches in length ; but in both
these cases the spicula must be considered as auxiliary, and
not essential forms.

The larger number of forms of skeleton spicula are per-
fectly smooth, but in some species they are partially or en-
tirely covered with spines.

OF THE SPONGIAD^E. 15

In every case they appear in the living state to have the
capability of a change of position within the fibre to a con-
siderable extent, in accordance with the natural alterations
arising from the extensions or contractions of those tissues.

The spicula are among the earliest developed organs of
the sponge. Dr. Grant, in his valuable " Observations on
the Structure and Functions of the Sponge," published in
the 'Edinburgh New Philosophical Journal,' vol. i., p. 154,
states that spicula are developed in the locomotive gem-
mules of HaUcondria panicea (Hal. incrustans, Johnston)
before they attach themselves for life and commence their
development as fixed sponges. And in the gemmules of
Tethea cranium they are abundantly developed even before
the gemmules are detached from the parent, and some of
them are forms peculiar to the gemmule.

The growth of the spicula and their mode of extension
appears to vary according to circumstances. Thus an ace-
rate spiculum is at first short and very slender ; as the de-
velopment proceeds, it increases in diameter, and appears to
lengthen equally from the middle towards both ends ; but
in spinulate ones the increase in length does not appear to
be effected in the same manner as in the acerate form, as
we often find spinulate spicula fully developed at the base,
while the shaft is exceedingly short and the apical termina-
tion hemispherical instead of acutely pointed, as in the
adult state. As the shaft lengthens towards its full propor-
tions, it attenuates ; but in all the intervening stages the
apical termination is usually more or less hemispherical.
The progressive development from the base to the apex of
the spinulate form is beautifully illustrated in the skeleton
spicula of a new and very singular British sponge from
Shetland, Halicnemia patera, Bowerbank, represented by
Pigs. 228, 229, 230, 231, 232, and 233, Plate X. Pig.
230 represents a short variety of the normal spinulate form.
In Fig. 228 we have a bi-spinulate, and in Fig. 229 a tri-
spinulate, form. The latter two are not mere malformations,
but they prevail to a great extent in the structures of the
sponge, subject to variations in the distances in the deve-
lopment of the second and third inflations from the basal

16 ANATOMY AND PHYSIOLOGY

one. Figs. 231, 232, and 233, represent immature spicula
in progressive stages of development, the apices having
hemispherical terminations.

Auxiliary Spicula.

Beside the spicula essential to the structure of the skele-
ton, there are several other forms of these organs, many of
which, although not absolutely necessary in the structure of
the skeleton, are of very frequent occurrence in subsidiary
organs found in particular species and in peculiar genera.
They may be conveniently classed under the following
heads :

Connecting spicula.

Prehensile spicula.

Defensive spicula.

Tension spicula.

Retentive spicula.

Spicula of the sarcode.

Spicula of the ovaries and gemmules.

In the above designations of the auxiliary spicula, it
must not be understood that their respective titles strictly
define their offices, as it frequently occurs that under pecu-
liar circumstances the same form of spiculum is destined to
serve two, or even three, distinct purposes. Thus, an ex-
ternal defensive spiculum will occasionally perform reten-
tive offices for the purpose of securing prey; or internal
defensive spicula will combine the offices of defensive
spicula against the larger and more powerful of their ene-
mies with that of wounding and securing their smaller ones.

The Connecting Spicula.

These spicula are not necessarily a part of the skeleton ;
they are a subsidiary portion of it, occurrring under special
circumstances in a few genera only, such as Geodia, Pachy-
matisma, and other sponges which have a thick crustated
surface, which they serve to support and retain in due

OF THE SPONGIAD/E. 17

connection with the mass of the animal beneath. The trira-
diate apices also serve to construct areas in which are
situated the proximal orifices of the intermarginal cavities,
which are imbedded in the crustated surface of the sponge.
The normal form of these spicula is very different from that
of the spicula which constitute the general mass of the
skeleton, and they are far more complex and varied in their
structure. They usually have a long, stout, cylindrical, or
attenuated shaft, terminating either acutely or hemispheri-
cally at the base, while the apex is divided into three stout
equiangular radii, which assume in different species a con-
siderable amount of variety as regards form and direction.
The triradiate apices are usually cemented firmly to the
inner surface of the crustated coat of the sponge, while the
stout and elongated shaft is intermingled with and firmly
cemented by keratode to the general mass of the skeleton.
From the trind nature of the apex, I have designated these
forms as ternate spicula, prefixing such terms as may best
serve to distinguish them individually in accordance with
their permanent variations from each other. The prefixed
designations of the spicula must necessarily in some mea-
sure be arbitrary, as the differences in the degree of the ex-
pansion of the radii cannot be strictly defined; and although
the forms are well characterised in each species, yet even
within these bounds a slight degree of variation, arising
from the local necessities of the case, \vill occur. The ter-
nate spiculum, therefore, as a general designation, may be
said to be an elongate spiculum, with a triple apical ter-
mination. These spicula are not confined to the office of
connecting only, but are also found among the defensive
ones, as will be hereafter shown they are best developed in
Geodia McAndrewii and Barretti, Pacliymatisma Johnstonia,
and others of similar structure.

I have never seen the progressive development from a
simple elongate shaft of an expando or patento-ternate con-
necting spiculum, as I have those of the porrecto-ternate
external defensive form, and the spinulo-recurvo-quaternate
internal defensive ones, but from the great similarity that

exists in their structure there can be little doubt that their

2

18 ANATOMY AND PHYSIOLOGY

mode of growth is the same ; and I am very much inclined
to believe that the cylindro-expando-ternate form from
Pachymatisma Johnstonia, Fig. 46, Plate II, is an incom-
pletely developed form of the mature attenuato-expando-
ternate spiculum that belongs to that sponge, and which is
represented by Fig. 45 in the same Plate.

There is a progression of development in the ternate
terminations of these forms of spicula that is very interest-
ing. The simplest form has three nearly straight attenuating
radii. In the next stage the distal ends of the primary
radii become furcated, but the secondary radii remain in
the same plane as the primary ones. In the third stage of
development the terminations of the secondary radii again
divide into furcations, becoming dichotomo-patento-ternate
(Fig. 53), but in this case the radii of the extreme furcations
are not all in the same plane, as appears always to be the
case with those of the secondary radii, and thus we have
produced an additional power for combined action. But in
the whole of these varieties, in the structure of these ternate
terminations, hitherto there is no appearance, further than
their general form, of their being destined to become a
united structure, and in some sponges in which they do
occur they rarely, or ever do, become thus united ; but this
demonstration of their destination for combined action is
obtained in an irregular ternate form, as exhibited in the
dermal structures of a new species of siliceo-fibrous
sponge from India, Dactylocalyx Prattii, Bowerbank, MS.,
in which we have the primary radii sinuated and flattened
in such a manner as to splice together and form a strong
and regular reticulated structure for the support of the
dermal membrane of the sponge, as in Fig. 300, Plate XX,
which represents a few of these spicula uniting to form the
reticulations of the dermal tissues, while Fig. 52, Plate II,
represents one of these spicula separated by boiling
nitric acid. By this structure, as exhibited in D. Prattii,
there is rendered apparent a more visible and common
purpose in their form and mode of development, and we
are gradually conducted to the still more complete and
continuous form of fibro-siliceous dermal network that

OF THE SPONGIAD.E. 19

exists in the beautiful harrow-shaped tissue of the dermal
structures of the sponge Farrea occa, Bowerbank, support-
ing the fine specimen of Ewplectella in the possession of
my friend Dr. A. Farre, and described by Prof. Owen in
the 'Transactions of the Linnean Society,' vol. xxii, p. 117,
plate 21, and which tissue I shall describe more fully in
treating on the subject of the dermal structures of the
Spongiadae.

There are two distinct purposes in the physiological
application of the ternate spicula; the simplest is that of
strengthening and connecting the dermal membrane
with the mass of the animal beneath. The second and
more complex one, is that of forming an internal reticu-
lating framework for the support within its areas of the
valvular tissues forming the bases of the intermarginal
cavities. These offices of the ternate spicula are not demon-
strated in an equal degree of perfection in all sponges in
which they occur. Where the organs which they subserve
are best and most abundantly developed, these forms
of spicula are found in the greatest quantities, and in
the most regular and perfect mode of arrangement, but
where the intermarginal cavities or porous areas are in a
less regularly developed state, they are deficient in a cor-
responding degree; thus evincing the design and purpose
of their structure and presence. The most perfect and
beautiful illustration of their physiological purpose, in their
first mode of application, is afforded by the dermal mem-
brane of Dactylocalyx Prattii. Here we find their radii,
as described above, overlapping each other longitudinally,
and cemented together by keratode, forming a continuous
and regular network, upon the upper surface of which the
dermal membrane reposes, and to which it is firmly united.
The mode in which the radii are united, and the material
with which they are cemented together indicate a unity of
firmness and elasticity in the living state that is truly
admirable ; and this mode of structure we perceive is
especially necessary to the action of the dermal membrane,
as the whole of the skeleton beneath is perfectly rigid and
inelastic. Thus while their shafts are deeply plunged in,
and firmly secured to, the immoveable mass beneath, their

20 ANATOMY AND PHYSIOLOGY

ternate apices are capable of such an amount of oscillating
motion, as would be required for the organic expansion and
contraction of the membranous structure they support.
By the action thus generated each pair of the united radii
would glide in a longitudinal direction upon each other, and
thus, although in each separate instance the amount of
motion would appear to be exceedingly small, the aggregate
of the whole would afford a very considerable range of
expansion, as exhibited in Fig. 306, Plate XX.

In their second mode of application, that is to the bases
of the intermarginal cavities, it appears that as their office
is different, so their form, and the mode in which the radii
of their apices is connected is also different. Thus at the
inner surfaces of the thick dermal crust of Geodia
McAndrewii and Barretti, we find them forming a network
equally regular and continuous as that in Dactylocalyx
Prattii, but the mode of its construction is varied. The
radii do not in these cases glide upon each other longitu-
dinally, but they cross each other at various angles ; and as
the whole mass of these sponges are fleshy and very elastic,
so by this mode of interlacement of the radii a very consi-
derably greater amount of expansion and contraction of the
reticulated structure is provided for, while at the same time
the power of maintaining the common plane of the reticulated
tissue is equally as great as in the similar structure in
Dactylocaly.v Prattii. Thus far we can trace the physiolo-
gical purpose of their structure ; but why in one species
we find their terminations simple as in Geodia McAn-
dreivii, and furcated as in Geodia Barretti, or still further
complicated as in the dichotomo-patento-ternate form, is
a question which cannot be so readily solved without a
further acquaintance with the species of Geodia bearing
these forms in a living state.

Prehensile Spicula.

Spicula projected from a sponye as a means of attachment
to other bodies. — I know of but one form of this description
of spiculum, an exceedingly elongated, fusiformi-acerate
one, with a stout recurvo-quarternate apex. It occurs at

OF THE SPONGIAD.E. 21

the bases of Euplectella asperyillum and E. citcuwer, Owen.
Tlie long attenuated basal portions of the shaft being
without spines, are incorporated with the longitudinal
fasciculi of the skeleton, while the apical portions of them
are projected from the base of the sponge, and embrace
and hook on to any extraneous mass near which it may be
situated ; and this free portion is thickly beset with strong
acutely conical spines, reflected at about the same angle
and in the same direction as the radii of the quaternate
apex, and to which they are auxiliary as prehensile organs ;
and as we proceed towards the central portion of the
spiculum, the spines successively decrease in length, until
at about one third of the length of the spiculum from its
apex they become obsolete. I am indebted to my friend
Dr. Arthur Farre for the specimen figured of this singular
and interesting form of spiculum ; and the only sponge in
which they have been found in a perfect state, is the deli-
cate and beautiful one designated by Professor Owen
Euplectella cucumer. They occur in great profusion,
embracing the mass of matter at its base in every direction.
I propose, therefore, to designate this form as an apically
spined recurvo-quaternate spiculum (Fig. 59, Plate III : a,
the apical portion of the spiculum ; b, a portion from that
part of the shaft at which the spines become obsolete).

Defensive Sjncula.

There are two classes of defensive spicula :-

1st. Those of the exterior,
2nd. Those of the interior of the sponge.

They are neither of them necessarily present in every species,
nor are they confined to particular genera, but occur occa-
sionally, and in certain species of various genera, apparently
as the necessities of the animal may render their presence
requisite. If the exterior of the animal be amply supplied
with them, the interior rarely possess them. Their office
is evidently to defend the sponge from the attacks of
predacious animals that would otherwise very probably

22 ANATOMY AND PHYSIOLOGY

destroy it ; and thus it is that the external defensive spicula
are frequently of more than the usual length and strength
of these organs. They are projected for about half or two-
thirds of their length, at various angles from the surface of
the sponge, apparently with the object of meeting the
attacks of the larger class of depredators ; but as between
the large spicula the smaller tribes of annulate animals
would readily insinuate themselves, there is frequently a
secondary series of defences, consisting of innumerable
short, finely-pointed spicula, the apices of which are pro-
jected a short distance only beyond the surface of the
dermal membrane, thus rendering the progress of the
smaller and more insinuating enemies extremely difficult,
if not impossible. In young sponges, as in Spougilla
flitviatilis and others, the office of external defensive spicula
is frequently performed by the continued extension of the
radial lines of the skeleton, the terminal spicula of which
often project to more than the extreme length of a spiculum
beyond the surface of the dermal membrane.

The arrangement of the spicula, in regard to their
especial office in the sponge, can only be approximately
correct as we frequently find them applied to what appears
to be abnormal offices ; thus the stellate forms, which are
especially applied to the protection of the sarcodous surfaces
of the interstitial membranes of the sponge, are occasionally
appropriated as external defences for the preservation of
the dermal membrane as in Tethea muricata, Bowerbank,
MS. (Fig. 35, Plate I). And the connecting spicula so
abundant within the crustular dermis of Geodia and Pliachy-
matisma are frequently, with various modifications of form,
applied as externally defensive and as tension spicula in the
dermal membrane, as in Dactyhcalyx Prattii, Bowerbank,
MS., as connecting and tension spicula and in the allied
form, with the addition of an external spicula ray and the
additional office of external defence, as represented by
Tig. 55, Plate II, from Geodia Barretti, Bowerbank,
MS. Similar spicula are found abundantly on the sur-
face of Dadylocalyx Bowerbankii, Johnson, in the British
Museum. The offensive is so frequently combined with the
defence office in the structure of some of these spicula,

OF THE SPONGIAD^E. 23

and it is so difficult, in some cases, to determine which of
the two, or whether both, are designed in the structure of
the spiculum, that I have not made a distinction between
presumed offices indicated by their structure, but have
classed the whole under the designation of the defensive
spicula.

When the defensive spicula are internal they usually
assume a different character from the external ones. The
most common form under these circumstances is that of
a short, stout attenuato-acuate spiculum, profusely and
entirely spined (Fig. 289, Plate XVII) ; they are firmly
based in the substance of the skeleton ; and the greater
portion of their length is projected at various angles from
the sides of the interstitial canals and cavities of the sponge.
They would thus render the passage of minute annelids
and other small enemies extremely difficult; and in one
instance, the mode in which the protection of the interior of
the sponge is provided for is very remarkable and curious.
Large spinulo-recurvo-quaternate spicula with attenuating
radii are grouped together on the angles of the network of
the skeleton, and are projected in a radiating manner into
the cavities of the interior of the sponge, forming a most
effectual prevention to the passage of any small animal
(Fig. 292, Plate XVIII). The occurrence of this complicated
and beautiful form of spiculum is a singular deviation from
the normal mode of defence, and almost induces the belief
that it was intended that such intruders as effected an
entrance were meant to be retained, and their decomposed
particles appropriated to the nutrition of the sponge. In
other cases, where no definite form of defensive spiculum
forms a part of the sponge, the office of those organs is
frequently performed by the projection of spicula similar to
those of the skeleton into the canals and cavities of the
interior.

If I were to attempt to enter upon a description of
every variation in the mode of the application of spicula
to defensive purposes, it would extend this portion of the
subject to a greater length than we can afford under the
present circumstances. I shall therefore confine my
observations to a description of the general principles of

21 ANATOMY AND PHYSIOLOGY

defence as exhibited in some of the principal genera of the
Spongiadse.

In the external defences, the mode of the application of
the spicula depends in a great degree on the structure of
the skeleton of the sponge. The most simple cases are
those where the structure of the skeleton consists of spicnla
radiating from the centre or the axes of the sponge, and in
these cases they usually consist of the terminations of the
radial lines of the skeleton, the distal spicula of which arc-
frequently projected for a considerable part of their length
through the dermal membranes, and in many sponges the
surface is thus thickly studded with them ; and in species
where the terminal radial lines of the skeleton contain
many spicula, they are frequently found at their apices to
assume a radiating direction, so as to present the greatest
possible number of points to their external enemies. This
mode of defence is very general in the numerous British
species of the genera Isodictya and ChaJina, Bowerbank.
Fig. 287, Plate XVII, represents a small portion of a section
at right angles to the surface from Ckalina seriafa, Bower-
bank, illustrating very distinctly this simple mode of
external defence.

In the genus DidyocyRndms, Bowerbank, which con-
sists principally of slender branching sponges, many of
which in their living state are exceedingly fleshy in their
appearance, the skeleton is formed of a central cylinder,
composed of a network of spicula, from the surface of
which radiate in vast quantities long, slender and acutely
pointed spicula, which in the living condition project
slightly beyond the dermal membrane of the sponge, so
that in the event of any small fish attempting to feed upon
or suck this tempting bait, instead of a mouthful of soft
and grateful gelatinous matter, he would find himself
assailed in every direction with an infinite number of
minute points, many of which he would carry away with
him deeply imbedded in the soft lining of his mouth, as
the reward of his temerity and a warning against a repe-
tition of a like assault. Fig. 365, Plate XXXII, represents
a small portion of a young branch of Dictyocylindrmrugosus,
Bowerbank, frequently found on shells and stones dredged

OF THE SPONGIADJ;. 25

up at Shetland, or the Orkney Islands. In the genus
Tethea, in which the skeleton consists of fasciculi of large,
stout spicula radiating from the base or centre of the
sponge, the system of defence is somewhat more compli-
cated. It is a combination of the terminations of the
skeleton fasciculi with, in some species, the addition at the
surface of the sponge of porrecto-ternate and recurvo-
ternate spicula ; the latter two forms being probably
aggressive as well as defensive, subserving the purpose of
entangling prey as well as that of defence.

This mode of defence is very beautifully illustrated in
Tethea cranium. Pig. 362, Plate XXXI. The distal ends
of the skeleton fasciculi, composed of large fusiformi-
acerate spicula, are projected through the stout coriaceous
surface of the sponge, and in the midst of this thick coat
each of the passing fasciculi is surrounded by a cluster of
stout short fusiformi-acerate spicula, their distal points
closely embracing the fasciculus, while their proximal
terminations are spread widely out in a circle around the
lower part of the skeleton fasciculus at b, so as to form a
strong and most efficient conical buttress to sustain it in

^j

its proper position, at the same time allowing a considerable
amount of elasticity to meet pressure from without. Each
skeleton fasciculus terminates with from two to eight or ten
porrecto-ternate spicula, and occasionally we find one or
two of the recurvo-ternate ones accompanying them ; but
their apices are rarely projected much beyond the dermal
membrane of the sponge, while the rest of the spicula
extend considerably above it. The same system of defences
prevails also in Tethea similiuia, Bowerbank, MS., from the
Antartic regions ; but in this species the recurvo-ternate
spicula appear to be protruded in greater numbers, and in
more regular order than in our northern species, T. cranium.
In Tetliea miricata, Bowerbank, MS., the skeleton
fasciculi are not protruded beyond the surface, but imme-
diately beneath it we find the heads of numerous large
furcated expando-ternate spicula, with remarkably long and
acute terminal radii, while the dermal membrane is pro-
fusely furnished with attenuato-elongo- stellate spicula,
Figs. 304 and 305, Plate XIX.

26 ANATOMY AND PHYSIOLOGY

In Tethea Norvegica and Int/alli, Bowerbank, MS., and
in T. lyncuriinn, Johnston, the same protection is attained
in a different manner. Instead of the spicula of the
skeleton fasciculi gradually converging towards a point,
they diverge considerably as they approach the surface, so
as to present an infinite number of minute and nearly
equidistant points, and in addition to these the dermal
membrane and the coriaceous coat of the sponge is supplied
with an infinite number of closely packed stellate spicula.

In some species of the genus Geodia the system of
external defences is still more complex. Thus in G.
McAndrewii and G. Barretti the defences are double, one
system consisting of a continuation of the great radial
fasciculi of the skeleton as a protection against the assaults
of the larger and more powerful assailants ; and then of a
secondary series consisting of an infinite number of minute
acerate spicula, based immediately beneath the dermal
membrane and projecting to a slight extent beyond its
external surface, effectually protecting it and the porous
system of the sponge from the attacks of its minute and
more insidious enemies,

Similar modes of external defences exist in various
species of Packymatisma and Ecionemia, but no two
.species appear to agree precisely in these respects.

In the genera Microdona and Hymeraphia, Bowerbank,
differing widely in the structure of their skeletons from any
of the sponges hitherto described, and frequently not
exceeding in thickness the substance of a stout sheet of
paper or a thin card, the same principles of defence are
carried out, although their structure is widely different
from each other. In the first genus, the skeleton of which
is formed of short pedestals of keratode combined with
spicula, each of the pedestals, which reach nearly to the
surface of the sponge, is terminated with a radiating
cluster of long curved and acutely-pointed spicula, the
apices of which pass through the dermal membrane in
every direction, and thus form a most effectual series of
external defences, while their shafts beneath serve as the
framework of the mtermarginal cavities of the sponge
(Figs. 368, Plate XXXIII, and 369, Plate XXXIV). In

OF THE SPONGIAD^E. 27

«

Hymeraphia, where the sponge is less in thickness than
the length of one skeleton spiculum, and where they pass
from the basal membrane of the sponge through the
dermal membrane, their apices acting as external defensive
organs, while their shafts form the essential skeleton of
the animal, there is an especial provision for their pre-
servation from injury. Their bases are expanded in the
form of large bulbs, so as not only to afford a greater
surface for attachment, but to allow them at the same time
to act on the principle of a ball-and-socket joint, giving
them a more than usual amount of attachment, and a
power of yielding in every direction to pressure on their
apices from without (Fig. 370, Plate XXXIV). The
defence of the surface of the Halichondroid sponges is
less apparent, but equally efficacious ; the abundantly
spiculous reticulations immediately beneath and supporting
the dermal membrane, would render attacks of annelids
or other small predaceous creatures exceedingly un-
palatable.

In the calcareous sponges the spicular defences are
exceedingly interesting. In Grantia compressa, the distal
ends of the great interstitial cells are amply protected
by numerous flecto-attenuato-acuate spicula grouped
around their porous terminations, with their club-shaped
ends curving in every direction over them, but in no
degree interfering with the freedom of their inhalant action.
In Grantia ciliata they are grouped in circles around the
distal ends of the interstitial cells (Fig. 345, Plate XXVI),
but in this species they are acutely pointed ; and when the
inhalant system is in a state of repose, they are concen-
trated at their extreme points so as to form an elongate
cone, effectually enclosing and protecting the porous ends
of the cells within them ; but when the inhalant action is
in full activity, their apices recede from each other until
they assume the form of a cylinder, and then freely admit
the incurrent streams of water, but effectually repel the
advances of any dangerous assailant that may attempt an
entrance. The distal termination of the cloaca in this
species is also abundantly protected by a marginal fringe
of long and very acute spicula, and is furnished with the

28 ANATOMY AND PHYSIOLOGY

same simple but beautiful mechanical contrivances for
opening and closing in accordance with the necessities
of the animal. For a more complete description of the
anatomy and physiology of this highly interesting species I
must refer my reader to the ' Transactions of the Microsco-
pical Society of London/ vol. vii, p. 79, pi. v.

In other species of Grantia the same principles of
external defensive action exists, but the precise mode is
never exactly the same in any two species.

Their external defences are the homologues of those of
the dermis of some of the Holothuriada and of Synapia.
Thus in Cucumaria communis we have the dermis fur-
nished with an infinite number of beautiful perforated
circular plates, from the centre of each of these is projected
outward a spiculated umbo terminating in numerous acute
points ; when the animal is irritated the whole of these are
projected from the dermis and the surface becomes bristling
with an infinite number of minute organs of defence. In
like manner Synapta is furnished with numerous anchor-
shaped spines which lie parallel to the dermal surface while
the animal is in an unexcited state ; but when irritated a
muscular contraction of the dermis takes place, the shank
of each anchorate spine is drawn inward, forming a
minute pit or depression, so that it becomes erect, and the
sharply pointed flukes, if we may so term them, are brought
into defensive position over the whole surface of the body
of the animal.

Internal Defensive Spicula.

The internal defensive spicula of sponges are exceedingly
various in their forms and modes of application to their
especial purposes ; and they seem naturally to resolve
themselves into three distinct groups : — 1st, those which
are destined simply to repel; 2nd, those which wound and
lacerate as well as repel ; and 3rd, those which are calcu-
lated not only to destroy but also to retain intruders.

The purposes of the first class of spicula are frequently
performed by the ordinary spicula of the skeleton, which
are projected more or less into the cavities immediately

OF THE SPONGIAD.fi. 29

within the oscula and other spaces requiring such pro-
tection ; but when especially formed for and appropriated
to defensive purposes, they are always free from spines and
usually terminate acutely ; and they are frequently pro-
vided with widely extended basal radii, so as to fix them
rigidly and firmly in their proper positions, as exemplified in
the various forms of spiculated triradiate spicula represented
by Figs. 85, 86, and 87, Plate IV.

The best illustrations of the application of the simple
defensive spicula are to be found in the cloaca in several
species of Grantia, as in G. ciliata, Johnston, and G.
tessettata and ensata, Bowerbank, MS. In all these
species this great central cavity is abundantly furnished
with spiculated triradiate spicula, which are so disposed
that while the basal radii are firmly cemented on the
surface of the cloaca, the spicular or defensive rays are
projected from its surface, not at right angles to its plane,
but always at such an inclination towards the mouth of
the cloaca as to present a combined series of sharp points
in the best possible position of defence, so that an
intruding assailant could scarcely escape being seriously
wounded by them, while a retiring enemy would pass
with impunity over their inclined apices. In some species,
as in G. tesselhita, the defensive ray is naturally curved to
the desired angle for defence (Fig. 86, Plate IV), and it is
also of such a form as to be readily released from the
creature it has wounded, either by being attenuato-acuate
or ensiform, as in Fig. 85, Plate IV, from G. ensata, and
as represented in situ by a small portion of a longitudinal
section of the cloaca of a specimen of Grantia tessettata
in Fig. 286, Plate I, in which the defensive radii are all
curved in the direction of the mouth of the cloaca.

In the second division the internal defensive spicula
are usually short and straight, and more or less covered
with strong conical acutely pointed spines, projected either
at right angles to the axis of the spiculum, or recurved
considerably towards its base ; generally speaking the
spines are dispersed on all parts of the spiculum without
any approach to order, as represented in Fig. 66, Plate III,

30 ANATOMY AND PHYSIOLOGY

while in other cases, as in Figs. 67 and 68 in the same
Plate, they are arranged in verticillate order on all parts of
the spiculum. In each of these varieties the bases of
the spicula are usually profusely furnished with spines
so as to ensure a strong and somewhat rigid mode of
attachment.

There is undoubtedly a special purpose in every variation
of the spination of these spicula, and in their presence
generally. The short strong form and acute distal termi-
nation admirably adapts them to encounter the larger
description of intruding annelids, the most dangerous
internal enemies of the Spongiadae ; while the spination
of their shafts presents a series of minute weapons that
would prove equally formidable to those intruders that
were too minute to be affected by the larger weapons
of defence.

The acuate entirely spined defensive spicula are of very
common occurrence in sponges, and are by no means
confined to particular tribes or genera. As a general
rule, when the external defences are very full and suffi-
cient, we should not expect to find the internal defences
abundant, and, on the contrary, when there appears to be
a paucity of external defences, the internal ones are fre-
quently exceedingly numerous. Thus, in the genus
Dicti/oci/lindrus, Bowerbank, where in almost every species
the surface of all parts of the sponge is bristling with the
acute terminations of the radiating external defensive
spicula, although in most of the species we find acuate
entirely spined internal defensive ones, yet in many of
the species they are so rare as to be by no means readily
detected.

When the skeleton is formed of keratose fibres, we find
them dispersed on their surface without any approach to
order, and projected at every imaginable angle. If the
skeleton be formed of any of the varieties of spiculous reticu-
lations, they are based in a similar manner on the prin-
cipal lines of the reticulated structure, and sometimes, but
not very frequently, they occur in groups.

I will not extend this portion of my subject to an

OF THE SPONGIADyE. 31

unnecessary length by describing every mode of their
occurrence, but select a few of the most interesting
cases as illustrations of the general principles of their
application.

Fig. 288, Plate XVII, represents a small portion of
the kerato-fibrous skeleton of an Australian sponge, with
the attenuato-acuate entirely spinecl internal defensive
spicula in situ. Fig. 289, represents a few fibres from a
kerato-fibrous sponge from the West Indies, in which the
vertici] lately spined internal defensive spicula are dispersed
over the fibres ; and Fig. 290 represents the same descrip-
tion of defensive spicula from a West Indian kerato-
fibrous sponge, having the defensive spicula congregated in
bundles. Sometimes, but not very frequently, they are
found on the interstitial or basal membranes of the sponge,
and under these circumstances many of them are prostrate
in place of being erect ; and in one sponge, Hymeniacidon
CUftoni, Bowerbank, MS., a singular parasitical species
from Freemantle, Australia, this prostration appears to be
effected by an especial law. This singular sponge enve-
lopes several fan-shaped portions of a Fucus, and syste-
matically appropriates the minute ramifications of its stem
to the purposes of an artificial skeleton ; the whole sponge
abounds with short stout attenuato-cylindrical entirely
spined internal defensive spicula ; but the remarkable
circumstance attendant on their presence is, that where-
ever the membranes supporting them envelope and firmly
embraces a portion of the vegetable stem, they assume an
erect position, and exhibit all the usual characters of
defensive spicula ; but where the membranes merely fill
up the areas of the vegetable network, they are nearly
all of them perfectly prostrate and apparently performing
the office of tension, rather than of internal defensive
spicula. Their form also is singular, being attenuato-
cylindrical. not having the acute termination that is usual
in this description of spicula.

Fig. 291, Plate XVII, represents a small portion of the
fibrous stem of the Fucus coated by the membranes of the
sponge, and covered with spicula ; those immediately over

ANATOMY AND PHYSIOLOGY

the stem being erect, while those on the membrane are
prostrate, (a) represents one of these new form of internal
defensive spiculum X 175 linear and (5) a small portion of
the surface of the Fucus showing its cellular structure
X 400 linear.

In Hi/merapltia steUifera, Bowerbank, an exceedingly
thin coating British sponge, the internal defensive spicula
present a singular variation from the normal form. In
this case they assume the shape of an ordinary Florence
oil flask, with a somewhat elongate neck, and having a
beautiful star-shaped apex in place of a stopper. They
occur in considerable quantities ; their large bulbous bases
are firmly attached to the strong basal membrane of the
sponge, and they are projected thence at every possible
angle upward into the interstitial spaces. Their apices
are crowded with stout acutely conical spines, which
radiate in all directions. Fig/ 730 a, Plate XXXIV,
represents a group of these spicula in situ, elevated by
a grain of sand beneath the basal membrane ; and Fig. 34,
Plate I, one of the same form of spiculum, magnified 260
linear. In this form of spiculum, as in that of Ilymeni-
acido/i Cliftoni, their purposes seems to be the infliction
of laceration, rather than that of destruction by deep
wounds. In another species of Hymeraplua, H. davata,
these spicula have the same large bulbous bases as those of
H. steUifera, but their apices are acute, like those of the
normal forms of such spicula. In all these cases we
observe in their attachments the same approximation to
the structure of the ball-and-socket joints of the higher
tribes of animals, rendering them capable of yielding in
every possible direction to the struggles of any enemy with
whom they may be entangled.

In the third division of the internal defensive spicula
there is an especial construction for retention as well as for
destruction. Their apices are usually more or less hamate,
as represented in Figs. 70, Plate III, and Figs. 81 and 82,
Plate IV, and their attachments to the sponge are usually
such as to alloAv of a considerable amount of flexibility
or motion.

OF THE SPONGIAD.E. 33

I will not attempt to describe the whole of the numerous
variations in the modes of application to defensive pur-
poses, but select a few of the most interesting cases as
illustrations of the general principles of combined internal
defence and aggression.

The spinulo-recurvo-quaternate spiculum (Fig. 76, Plate
III), presents an admirable illustration of the combined
defensive and aggressive character of some of those internal
defensive spicula. The sponge in which they occur
belongs to the Halichondroid tribe, the skeleton being
composed of a network of spicula cemented together by
their apices, which cross each other at the angles of the
areas of the reticulations. The recurvo-quaternate spicula
are not dispersed on all parts of the skeleton, but are
congregated in groups, frequently consisting of as many as
fifteen spicula, the whole of their bases being concentrated
on one of the angles of the reticulations of the skeleton,
while their shafts and apices radiate thence in every
direction into the interstitial spaces of the sponge ; they
are thus placed on the strongest and most elastic portion
of the skeleton, with their hemispherical bases firmly
imbedded in the cementing keratode of the skeleton,
which abounds at the angles of the network, and which
by its inherent elasticity and strength renders the insertion
of the base of the spiculum, in strength and extent of
action, quite equivalent to the powers of the ball-and-
socket joints in the higher tribes of animals. A small
annelid or other minute intruder entangled amidst these
numerous sharp hooks would struggle hopelessly in such a
situation, as the spicula, from the nature of their attach-
ment, would yield readily to its struggles in every possible
direction, and at every new contortion arising from its
efforts to escape it would inevitably receive a fresh series of
punctures and lacerations.

Fig. 292, Plate XVIII, represents a small portion of
the skeleton of the sponge bearing the spinulo-recurvo-
quarternate spicula in situ.

The gradual development of this form of spiculum is
interesting and very instructive. In an early stage of

3

34 ANATOMY AND PHYSIOLOGY

its development it has the appearance of a slender inequi-
biclavate cylindrical spiculura (as represented in Plate III,
Fig. 73) ; in the next stage there is a slight indication
of the spinulate base, and a corresponding amount of
expansion of the apex, but no indication of the radii
(Fig. 74). From this state to the next well-marked stage
of growth (represented in Fig. 75) the progressive develop-
ment of the radii may be readily traced, and thence to the
adult condition represented in Fig. 76.

In its fully- developed state we find a great increase in
its size in every respect ; the base becomes fully developed
and globular, and the radii elongated to a very considerable
extent.

In other instances, where defence alone appears to be
contemplated, we do not find these beautiful adaptations
for motion in every direction prevail. The bases of the
spicula in those cases are abundantly spinous, and are
evidently intended to maintain a firm hold by their
attachments, and are destined rather to rigidly maintain
their position than to yield to any struggling body with
which they may be in contact. The numerous spines with
which these shafts are frequently covered are calculated to
wound and lacerate, rather than to retain the enemies with
which they are engaged.

I have received from my friend, Mr. J. Yate Johnson, of
Madeira, a new and very illustrative instance of the combi-
nation of defence and aggression in the structure and
offices of the internal defensive spicula ; and in this case it
is not a new organ, but an adaptation of a well-known
form to a new purpose, in the shape of a contort trenchant
bihamate spiculum of unusual size and structure. In the
course of my examination of the results of the deep-sea
soundings in the Atlantic, I found several of these spicula,
and was much interested by the singularity of their struc-
ture, which at that time I could not comprehend.

The general outline is much like that of the type-form
so commonly found imbedded in the sarcode, but it is
somewhat less flexuous in its curves, and the shaft and
hami are very much larger and stouter than those of the

OF THE SPONGIAD^E. 35

spicula of the sarcode. But the most singular point
in their structure is, that while the curved portion of
the hami and the middle of the shaft are perfectly cylin-
drical, the inner portion of the hooks and those parts
of the shaft immediately opposed to them present sharp
trenchant edges, so that each hook assumes to some extent
the form of spring hand-shears. The acute termination of
the hook and the opposed trenchant edges exhibit every
facility for effecting an entrance through the tough skin of
the victim, while the perfectly blunt and cylindrical state of
the arch of the hook bespeaks the design of retention as
well as of destruction. As soon as the hook has penetrated
to the inner blunt surface of the curve it no longer cuts,
and the prey wounded in every direction is securely
retained for the nutrition of the sponge. This result is
not indicated only by the form of the spiculum ; their
position in the structure of the sponge bespeaks their
office equally unmistakably. They are not immersed in
the sarcode like their congeners in form, but are firmly
cemented by one hook to the reticulating lines of the
skeleton, while the other ends are projected at various
angles into the interstitial cavities of the sponge in such
numbers and in such a manner, that it would be next
to impossible for an intruder within the sponge to escape
being entangled and destroyed amongst them. Fig. 293,
Plate XVIII, represents a portion of the reticulated
skeleton of the sponge with the trenchant contort bihamate
spicula in situ, magnified 50 linear ; and Fig. 112, Plate V,
one of the spicula, magnified 400 linear, to exhibit the
trenchant edges and the cylindrical portions of the hami
and shaft.

This sponge is allied to Hymedcsmia by the structure of
the skeleton, and it is described by my friend, Mr. J. Yate
Johnson, as being a thin coating species spreading over
the surface of rocks and stones to the extent of two or three
inches in diameter.

In Hyalonema mirabilis, Gray, a sponge nearly related to
the genus AlcyonceUnm Q/toy et Gaimard, we find another
extraordinary series of internal defences ; one portion of

36 ANATOMY AND PHYSIOLOGY

the spicula appearing to be destined to wound and lacerate,
rather than to retain intruding enemies, Avhile a larger
and stronger series of spicular weapons bear all the
evidences of being to retain rather than to repel the
assailants.

The first description of spiculmn I have designated
entirely spined, spiculated cruciform spicula. They con-
sist of a short stout cruciform base with a long spicular
ray, ascendingly and entirely spinous, projected at right
angles from the centre of the basal radii. The spines are
acutely conical, and very sharply pointed. They pass off
from the spicula ray at an angle of 12 or 15 degrees in
the direction of its apex. The apices of the basal radii
are attenuated and slightly spined. These spicula are
thickly distributed on the fasciculi of the skeleton, and
frequently equally so on one side of the interstitial
membranes, probably that which forms the surfaces of the
interstitial spaces, and they are especially abundant near
the exterior of the sponge. The four basal radii appear
firmly cemented to the membrane, but not immersed in
its substance, as they do not appear to leave their impres-
sions when removed from it, nor do they bring any portion
of the membrane away with them. In some parts of the
tissue these spicula are very much modified in form. In
the ordinary cases we find the basal radii short and stout,
and not more than a fourth or a fifth of the length of the
spicular ray, while in other cases the basal rays are very
nearly as long as the spicular one ; the only difference
in their structure being that the latter is very strongly
spinous, while the former have the spines comparatively
very slightly produced.

The second form is a large fimbriated multihamate
birotulate spiculum, which occurs dispersed amid the
interstitial tissues of the large basal mass of the sponge.
There are usually not more than one or two together, but
occasionally they occur in groups of ten or twelve, without
any approach to definite arrangement.

These spicula are comparatively large and stout. They
have eight rays at each end of the shaft ; the two groups of

OF THE SPONGIAD^E. 37

radii curving towards each other to such an extent that
each forms the half of a regular oval figure ; the opposite
apices being separated to the extent of about the length of
one of the radii. Each ray is in form like a double-edged
blunt-pointed knife, bent near the handle in the direction
of a line at right angles to one of its flat sides ; and each
ray is strengthened and connected with the shaft of the
spiculum by a stout curved web of silex, which extends
from a little below the inner surface of the ray to a point
on the shaft about opposite to its middle. The shaft is
cylindrical, and has short stout tubercles dispersed over all
its parts when fully developed.

The structure of every part of this singularly beautiful
spiculum is strikingly indicative of its office in the economy
of the sponge ; the form and mode of bending of the radii,
with their thin edges at right angles to the line of force in
a struggling animal, and the powerful web at the base of
the ray enabling it to sustain an amount of stress that the
unsupported flat ray would never otherwise be able to endure.

The spiculated cruciform spicula are exceedingly
abundant in every part of the sponge, and no victim
entangled and retained by the large multihamate spicula
could avoid innumerable wounds while struggling to effect
its escape ; while the one held it secure within the sponge,
the others, from the peculiarity of their form and mode of
the disposition of their acutely pointed spines, would
readily release it after the infliction of every puncture,
only that the wounds might be multiplied until the
creature was pierced in every part, and bled to death for
the nutrition of the sponge.

Tig. 294, Plate XVIII, represents a small portion of
the skeleton of Ihe sponge with the two forms of defensive
and aggressive spicula in situ, magnified 50 linear. Fig.
60, Plate III, represents one of the multihamate bihamate
spicula with a power of 83 linear, displaying the adap-
tation of its structure to purposes of retention. Fig.
295, Plate XVIII, represents one of the spiculated cruci-
form spicula magnified 175 linear, on the same scale as
Fig. 60, Plate III, showing their relative proportions.

38 ANATOMY AND PHYSIOLOGY

It would be almost an endless task to describe every
variety of those singularly beautiful contrivances for com-
bined defence and offence in the interior of the Spon-
giadae. Those which I have particularised are some of
the most elaborate and beautiful that I have seen during
the course of my researches. In many other cases, where
all that is required is defence, the means employed are of a
much more simple nature. We find in the Spongiadse, as
in other animals, that nature frequently economises her
means by the conversion of one organ to the purposes
of another by slight adaptations or additions ; thus in
Halichondria incrustans, Johnston, and in other sponges,
the skeleton spicula are made to perform the duties of
internal defensive spicula, by being more or less furnished
with spines, as represented in Fig. 28, Plate I, and in other
cases where we find them medially or apically spined, as in
Figs. 30 and 32 of the same Plate.

In like manner we find the spicula of the sarcode, by
the extreme profusion in which they occur in that sub-
stance near the surface of some sponges, are turned to good
account for the general purposes of external and internal
defence, as well as for their special purpose of protection
and support of the sarcode. So likewise in the tension
spicula of Sponyilla lacustris (Fig. 90, Plate IV,) they are
made to serve as defensive organs as well as tension
spicula; and, again, in the spicula of the ovaries of the
Spongiadae their skeleton spicula also perform the office of
defensive as well, as represented by Figs. 203 and 204,
Plate IX.

As regards, then, their protection from their enemies,
there appears to be almost a natural prohibition to the
sponges becoming, to any great extent while alive, the food
of other creatures. The keratode of their skeletons
appears to be almost indestructible by maceration or
digestion, and the abundance of the acutely pointed
spicula that exists in so many of their bodies must render
them anything rather than desirable or digestible food
to the generality of other marine animals ; and in truth I
do not know of a single large fish, or other marine creature,

OF THE SPONGIAD^E. 39

that appears to prey upon them. The only animal in the
stomach of which I have ever seen the spicula of any
sponge was a Doris. But although appearing to enjoy
almost an immunity from the common lot of animals,
that of being eaten by others, they may yet serve at
their death by natural causes to supply an immense
quantity of animal molecules for the sustenance of the
myriads of minute creatures that exist around them.

Spicula of the Membranes.

There are two distinct classes of spicula appropriated to
the membranous tissues of sponges. The office of the first
of these is simply to strengthen and support those delicate
tissues when necessary, and to communicate to them a cer-
tain amount of tension when it is required. The forms are
few in number, and their structure comparatively simple.

The office of the second class is that of assisting in the
retention and protection of the sarcode on the interstitial
and other membranous structures. They are usually mi-
nute in size, and often very complicated in form.

I propose to designate these organs as —

1st. Tension Spicula.
2nd. Retentive Spicula.

Tension Spicula.

In some species of sponges the dermal membrane is
without spicula especially appropriated to it, and it then
appears, as in Spouf/illa fluviatilis, to be a simple trans-
lucent membrane filling up all parts of the network of the
external surface of the skeleton, and closely adhering to it ;
but the membranous areas thus formed are devoid of pecu-
liar forms of spicula. In other cases, as in Spongilla lacns-
tris, we find spicula dispersed more or less abundantly over
the whole of the surface of the membrane, which are entirely
unconnected with the skeleton, and give to the dermal
membrane a degree of firmness and tension that it would

40 ANATOMY AND PHYSIOLOGY

not otherwise possess. These spicula are sometimes of the
same form as those of the skeleton, as in Halichondria
panicca, Johnston, where we find them thickly, but irregu-
larly dispersed on the inner surface of the dermal mem-
brane. In some cases they are not readily to be distin-
guished from those of the skeleton, as they are frequently
so nearly of the same size, and are intimately intermingled
with them, as in the genus Hymeniacidori ; but in others,
as in some species of Clidlina and Isodictya, they may be
distinguished by their position, and by the total absence of
keratode around them, while those of the skeleton are al-
ways more or less coated by that substance.

In other species they differ materially in form and pro-
portion from those of the skeleton. Thus in Halichondria
incrustam, while the skeleton spicula are stout, short, en-
tirely spined and acuate, as represented by Fig. 28, Plate I.
The tension spicula are smooth, slender mucronato- cylin-
drical, as represented by Fig. 92, Plate IV. They are fre-
quently dispersed on the dermal membranes, much in the
same manner as they are on the interstitial ones, aboun ding-
most where the areas are largest, and where the areas are
small they are few in number or entirely absent ; but in
other cases, as in the dermal membrane of HaUchondria
incrusians, they are congregated in flat broad fasciculi,
which are disposed on the membrane with little or no ap-
proximation to order.

In the interstitial membranes the same object is fre-
quently attained by the incipient skeleton spicula, and we
often find either very young and minute skeleton spicula in
the membranous areas of the network of the skeleton, or
there will be one or more spicula very little less in size
than those of the skeleton, imbedded in the surface of the
membrane, but quite unconnected with the surrounding
skeleton ; or occasionally connected by one termination
only, but ultimately by the development of other spicula,
becoming incorporated with, and forming part of the skele-
ton. And it is not in the Halichondraceous sponges only
that the tension spicula occur, for we find them abundantly
dispersed in the dermal membrane of one of the Turkey

OF THE SPONGIAD^. 41

sponges of commerce, the honeycomb sponge of dealers, in
which siliceous spicula play a very subordinate part in the
construction of the skeleton.

The tricurvo-acerate form in all its varieties is better
calculated to effect their peculiar office in small and irregu-
lar spaces, and with greater economy in numbers, than the
straight elongated forms, and they are also better adapted
to membranes having unequal surfaces, such as those in
Microciona armata, Bowerbank, where we see them follow-
ing the undulations of the membranes and sustaining them
in their proper positions around the columnar parts of the
skeletons. The varieties of form in these spicula are well
represented in Figs. 96, 97, and 98, Plate IV. They are
all out of the same sponge. In Grantia compressa, and
other closely allied species, where the structure is systema-
tically membranous, the skeleton spicula are triradiate,
supporting the membranes in uniform planes in the most
effectual manner ; and they are in fact systematically tension
spicula, as well as skeleton ones. In Lenconia nivea, Bower-
bank, which is not symmetrical in its structure, like G. com-
pressa and its congeners, other forms of tension spicula are
developed to suit their especial purposes, such as repre-
sented by Figs. 100 and 101, Plate IV.

In siliceous sponges we also occasionally find triradiate
spicula developed and performing the office of tension
spicula in the midst of comparatively large membranous
areas ; but these forms, in every case under such circum-
stances in which I have seen them in situ, appear to belong
to the exception, rather than the general rule obtaining in
such sponges.

The foliato-peltate spicula — for a full account of the pro-
gressive development of which I must refer to Terminology,
number 102 — appear to be a development of the apices of
connecting spicula into dermal tension ones, bearing a
strong resemblance in form and purpose to the bony scutes
in the skins of some of the higher animals ; while the ex-
treme crenulation of their margins probably served the
purpose of facilitating the action of the porous system.

In all the varieties in form which I have hitherto de-

42 ANATOMY AND PHYSIOLOGY

scribed, and with which I am acquainted, where they per-
form the office of tension spicula only, they are destitute of
spines. In other cases the tension spicula not only fulfil
their own especial office, but they subserve that of defen-
sive spicula also. Thus in the dermal membrane of Spon-
yilla lacustris, Johnston, we find them dispersed rather
numerously, covered with short acutely conical spines, as
represented by Fig. 90, Plate IV. In Spoiigilla alba, Carter,
we find the tension spicula as abundantly spinous as those
of S. lacustris, but in this case the spines are truncated
(Fig. 91, same Plate). They have a similarly blunted im-
perfectly produced character in those of Pachymatisma
Johnsfonia, as represented by Fig. 93.

The production of tension spicula in the membranes of
the Spongiadae is by no means a peculiarity of that class of
animals. We find them in numerous beautiful forms in the
skins of the Holothuriadas, varying in shape in the different
parts of the animal to adapt themselves to the necessities
of their situation ; but the closest approximation, both in
size and form, to those of the Spongiadas are the bihamate
ones that are found so abundantly dispersed on the mem-
branous tubular suckers of Echinus sphcera ; and I have
also seen another variety of these spicula in the tubular
tentacles of a large common species of Actinia ; and in
the latter case they were even more minute than those of
the Spongiadas.

Retentive Spicula.
1st. Bihamate Spicula.

In the interior of the sponge we find a series of retentive
organs in the various forms of bihamate and anchorate
spicula, which exist in large numbers attached to the
surfaces of the interstitial membranes. The simplest forms
of spicula of this kind are those of the bihamate, in which
we have an acerate form of spiculum, bent near each termi-
nation into the shape of a hook, the curves being either in
the same plane or at right angles to each other, and the
terminations being attenuated and acute.

OF THE SPONGIAD.E. 43

The variety in the amount of curvature at the middle of
the shaft of the spiculum is also very great, as represented
in Plate V, Figs. 109 to 121"; but these variations are not
purely accidental ; on the contrary, they are more or less
constant in each species of sponge, and frequently afford
good specific characters.

In the simple bihamate form, where the two hami are
curved in the same plane and towards each other, the
spiculum, in its natural condition, is usually attached to
the surface of the membrane by the middle of the back of
the curved shaft, and the two hooks are projected into the
sarcode at right angles to the plane of the membrane on
which it is based. When the hami are developed reversed
or at right angles to each other, one of them is then usually
imbedded sideways on the membrane, and the other with
the shaft is projected from the plane beneath into the
sarcode at various degrees of angle. Or in the deflected
form the shaft may be firmly cemented to the membrane
by one side, while the hami are both projected upward into
the mass of sarcode. In some species of sponge one or the
other of these forms especially prevails, but in others, as
in Halichondria incrustans, Johnston, the simple, reversed,
and contort forms are indiscriminately mixed in the tissues,
and they occur in every imaginable form of attachment
in great profusion, and accompanied by the anchorate
forms as well.

However varied they may be in form, when they are in
their normal positions their office appears to be purely
retentive. They are generally produced singly, and are
dispersed without any approach to regularity over all
parts of the sarcodous membranes of the sponge, abound-
ing in some situations to a very much greater extent than
in others. Their positions on, and mode of attachment
to, the membrane are exceedingly varied, but in almost
every instance it is such as to render the spiculum obviously
subservient to the retention of the sarcode on the mem-
branes which it covers. In one instance only I have found
the simple bihamate spicula congregated in loose fasci-
culi. In this sponge, a new and very interesting species,

44 ANATOMY AND PHYSIOLOGY

Hymedesmia Zetlandica, Bowerbank, they occur in great pro-
fusion. Very few of them occur singly ; nearly the whole
of them are found in rather loose fasciculi, and the number
is generally so great in each as to render it very difficult
or impossible to count them. The mode of their dis-
position in the bundles is symmetrical, all the hami being
in the same plane and coincident in direction, as repre-
sented in Fig. 296, Plate XVIII, bundles of reversed
bihamate spicula was observed, and these in like manner
were coincident in every respect like the simple bihamate
ones.

The type of this form of spiculum, the simple bihamate,
is not peculiar to the Spongiadse ; it occurs in a much
more highly organised class, in a radiate animal, Echinus
sphcera, Forbes, ' British Starfishes,' where we find an
abundance of these organs disposed on the external surface
of the tubular suckers of the animal, but they are composed
of carbonate of lime instead of silcx. I am indebted to
my friend, the late Mr. John Howard Stewart, for my
knowledge of this interesting fact.

From the simple bihamate forms there appears a pro-
gressive development through the uniclavate and biclavate
forms represented by Figs. 118, 119, and 120, Plate V,
and the unipocillate and bipocillate forms represented by
Figs. 123, 124, 125, 126 and 127, Plate V, to the fully
developed anchorate forms of spicula.

In the simple form of pocillated bihamate spicula, the
terminations of the curved shaft resolve themselves into
two nearly equal, circular, concavo-convex plates, the
convex surfaces being in each case outward, and the sides
of each plate curving considerably towards the other, their
planes being at a right angle to the axis of the shaft. In
other cases, one cup will be developed with its plane in the
same direction as the axis of the shaft, while the other cup
is produced with its plane at right angles to the axis, and
also of the plane of the first cup. In these variations
of development, therefore, this form of spiculum may be
compared to tne simple and contort forms of bihamate
spicula ; and in truth they differ from them only in this,

OF THE SPONGIAD.E. 45

that in the one the terminations of the haini are attenuated
and acute, and in the other they are expanded into concavo
convex discs.

These two modes of development appear to be subject
to a considerable amount of variation in the growth of the
terminal discs ; as in some cases we find the distal part of
the terminal plate to consist of a uniform curve, while in
other cases the shaft is carried through the centre of that
curve, forming, as it were, a supplemental hook. These
variations are in perfect accordance with the general laws
of development in this class of spicula, as we find, both in
the'bihainate and anchorate forms, a considerable amount
of difference in the structure and position of these organs in
the same species of sponge.

A similar organic relationship appears to exist between
the umbonate forms of bihamate spicula represented by
Figs. 115, 116 and 117, Plate V, and the eccentric
trirotulate forms represented by Figs. 133 and 134,
Plate X.

2nd. Anchor ate Spicula.

The anchorate spicula, unlike the bihamate forms,
appear never to occur reversed or contorted, but always
to present their terminations in the same position as those
of the bow of an ordinary ship's anchor. In some sponges
they are tolerably uniform in shape and proportions, while
in others they vary exceedingly, not only while in course of
development, but even in their adult condition ; they glide
so insensibly from one form into another that it is difficult
to draw a distinction between them ; and yet, notwithstand-
ing this latitude in shape and development, they are very
.characteristic of species, as there are always a sufficient
number of fully developed ones that exhibit the normal
form.

In almost every case of their occurrence, beside the large
and fully developed organs, we find a secondary series
accompanying them, which are very much smaller in size,
and vary exceedingly both in symmetry and amount of

46 ANATOMY AND PHYSIOLOGY

development ; and there is every appearance that they are
simply abortive developments of the larger and more perfect
organs, with which they always appear to agree in their
normal characters.

There are two primary divisions of these forms of spicula,
— equi-anchorate, when both terminations are produced to
an equal extent, as in Figs. 140, 141 and 142, Plate VI,
and inequi-anchorate, when the distal termination is largely
and fully developed, while the proximal one is, compara-
tively, produced to a very limited extent, as in Figs. 137
and 138, Plate VI, each of these is subject to a certain
extent, to similar degrees of further diversity of form,
which may be designated biclentate, tridentate and
palmate. These forms are in truth but different degrees of
development of the normal palmate form ; but as we find
these variations constant in different species of sponges, it
is desirable that they should be separately designated,
as they afford excellent specific characters. Thus in
Halicliond/ria granulata, Bowerbank, we find large equi-
anchorate spicula, in which the lateral expansions of each
end of the curved shaft or bow which forms the palmate
terminations of the spiculum extend along the shaft towards
the middle of the bow, very little beyond the point of
curvature forming the basal commencements of the hooks ;
but although not decurrent on the shaft, the lines of the
inner margins are projected forward at an angle of about
45 degrees to the axis of the shaft; and as the outer lines
are projected in a corresponding degree, we have the palm
produced in the form of two concave conical teeth or palms
at each end of the spiculum ; and between these there is
not the slightest appearance of the ends of the hami, which
appear to be equally divided between the terminal palms or
teeth. This form I therefore term bidentate equi-anchorate..
The same termination occurs among the inequi-anchorate
forms ; and this mode of the development of the teeth
is well shown in the distal or larger portion of the bidentate
inequi-anchorate spiculum, represented in Tig. 137, Plate
VI. In other cases the termination of each hook does not
thus merge in the teeth, but is carried forward between

OF THE SPONGIAD.E. 47

them either in the form of a simple attenuated termination,
as represented in Fig. 140, Plate VI, or it expands laterally
and forms a third intermediate tooth of a hastate form,
as represented in Fig. 147, Plate VI. In either of these
cases I therefore designate the spiculum as tridentate. In
other cases, the lateral expansions forming the palm are
continued along the shaft of the spiculum to nearly, or
quite, the full extent of the palm, forming a single,
undivided, more or less concave termination, as in Fig. 138,
Plate VI. I propose, therefore, to designate this form as
palmato-anchorate ; and intermediate forms between the
decidedly dentate or palmate ones would be designated as
tridentato-palmate (Fig. 138, Plate VI), the palmate form
being in excess of the dentate structure ; or palmato-tri or
bi-dentate, when the teeth are in the ascendant.

Generally speaking, the ends of the shaft of each
anchorate spiculum either become obsolete at the base of
the teeth, as in bidentate forms, or they are continued in a
regular curve, forming the third tooth, as in the tridentate
form ; but in some cases, as in Halichondria phiinosa,
Johnston, the shaft appears to terminate abruptly at each
end, and the palms or teeth are projected towards each
other at a sharp angle to the ends of the shaft or I)OAV
of the spiculum : in this case we should term the spiculum
angulated anchorate, as represented in Figs. 141, 142 and
143, Plate VI.

The anchorate spicula are not, like the acerate, acuate
and other simple forms, of the same shape, or nearly so,
from the commencement to the termination of their
growth, but, on the contrary, they are developed pro-
gressively.

In a new species of Halichondria, for which I am
indebted to my late friend, Mr. Thomas Ingall, the
course of their development is displayed in a very interest-
ing and instructive manner. The first condition in which
we detect them is in the form of an exceedingly slender
and elongated simple bihamate spiculum, which is readily
distinguished from the true bihamate form by the straight-
ness of the shaft, the comparative shortness of the hami, and

48 ANATOMY AND PHYSIOLOGY

the obtuseness of their terminations,, as represented in
Pig. 144, Plate VI. We next find the same form increased
in strength, and with slight lateral fimbriae near each end
of the shaft at the commencement of the hami, as in Yi&.

* o

145, Plate VI. In a more advanced state we find a
regularly curved extension of the fimbriae, slightly so
at one extremity of the shaft, and considerably so at the
other ; and as the development progresses, the curves
of the fimbrise are extended in an outward direction, and
become angular; the extremities of the hami expand
laterally and assume a foliated appearance, as seen in
the distal or larger end especially (Fig. 140, Plate VI),
but the fimbriee at the smallest or proximal end of the
spiculum, and the foliated extremity of the adjoining
hamus, are still separated from each other; and this
progressive development may be observed in all its stages,
until the connexion of the parts is completed, and the fully
developed form represented in Pig. 147, Plate VI, is
produced. The same progressive development of this form
of spiculum may be traced in those of Hymeniacidon linguat
Bowerbank, from the Hebrides.

In the performance of their natural office in the sponge,
we find the same laws of attachment and projection obtain
that I have described in treating of the bihamate spicula.
In the equi-anch orate forms, where the terminal palms
or teeth are equally developed, the shaft is attached by the
middle of the external curve ; but in the inequi-anchorate
forms, where one palm is developed to a very much greater
extent than the other, we find the smaller one is attached
to the membrane, and the larger is projected at about
an angle of 45 degrees. Generally speaking, the ancho-
rate spicula, like the bihamate ones, are irregularly dis-
persed over the surface of the membranes, but occasionally,
as in Ht/meniacidon lingua, they are developed in circles or
rosette-formed groups.

In many cases these groups contain so large a number of
spicula as to render any attempt to count them ineffectual,
and in some instances so many are developed that the
group assumes the form of a ball rather than that of a

OF THE SPONGIAD^E. 49

rosette. Fig. 297, Plate XVIII, represents a rosette-
shaped group containing about the usual number of
spicula.

Besides the rosette-shaped groups in Hymemacidon lingua,
there are a considerable number of these spicula dispersed
over the surfaces of the membranes, but the attachment of
these spicula is more frequently at the middle of the shaft
than at the smaller end of the spiculum, their normal point
of attachment. In the single and separate mode of dis-
position they are performing the office of equi-anchorate
spicula, and the mode of their attachment is varied accord-
ingly ; but under these conditions they are rarely ever so
fully developed, nor do they attain the same size as those
which form the radiating groups. Notwithstanding the
numerous groups and dispersed spicula of .the inequi-
anchorate form, this sponge is also abundantly furnished
with bihamate spicula of various forms, but they are never
congregated like the anchorate ones.

The same radiating mode of arrangement occurs in
a parasitical Australian sponge from Freemantle, but the
form of the terminations of the spicula is very different
from those of Hymemacidon lingua. The distal termination of
each of the inequi-anchorate spicula is shortened in length,
but expanded laterally to a considerable extent, and
its terminal edge is furnished with three thin pointed
teeth. The distal end has two small expanded and raised
wings, projected in the direction of the inner curve of the
spiculum, and so disposed as to cause it to resemble very
closely an engineer's spanner for bringing up to their
bearings projecting square-headed screws. Thus, although
the forms of the termination of the two varieties of spicula
vary to a considerable extent, the principles of their
structure and purposes are in perfect unison. Pig. 135,
Plate VI, represents a single spiculum highly magnified
to display the peculiarity of their structure.

As may be imagined, from their office and situation in a
thin stratum of a gelatinoid sarcode, they are at all times
small, and in many cases so minute as to require a micro-
scopic power of at least 600 linear to render their structure

4

50 ANATOMY AND PHYSIOLOGY

distinctly visible. They occur in all parts of the sarcodous
surfaces of the interior of the sponge, and are frequently
found in greater profusion than usual on the inner or
sarcodous surface of the dermal membrane ; but I do
not recollect an instance of their occurrence on the outer
surface of that organ, while on the sarcodous or interstitial
membranes they are frequently to be observed in about
equal proportions on both sides of the same membrane.

It will not be necessary to describe or figure the whole
of these variable forms of spicula. I have therefore selected
those only that may be considered more especially as type
forms.

Spicula of the Sarcode.

As the tension spicula of the membranes are destined to
strengthen and support those tissues, so the numerous and
beautiful tribe of stellate spicula appear to be devoted to
connect and give substance, and in some instances to
defend the gelatinoid sarcode, which so abundantly covers
the whole of the interior membranous structures of the
sponges in which they occur. It is difficult at first sight
to determine the difference in the office of this class of
spicula, and those of the internal retentive ones ; and it is
probable that in some cases, when it so happens that the
radii of the stellate forms rest on, and become cemented to
the membranous structures, they may perform, to a certain
extent, the same function, that of assisting to connect the
membranes and sarcodous structures more firmly together.
But generally speaking this is not the case, and especially
with the smaller forms of these organs ; for in compara-
tively thick layers of sarcode we find them in all parts, and
manifestly unconnected with the membranes beneath ;
and in sponges which have undergone such an amount
of decomposition as to leave the membranous structures
entirely, or very nearly, free from sarcode, while we see
the retentive forms remaining firmly attached to the
membranes, we rarely find the stellate ones, excepting
when entangled among the surrounding spicula of the

OF THE SPONGIAD^l. 51

skeleton. We may, therefore, reasonably conclude, that
their normal function is that of increasing the strength and
substance of the sarcodous structure of the sponge.

In the performance of this office of strengthening and
supporting the sarcode, we find a singular class of spicula,
consisting of from three to six rays, emanating from a com-
mon centre, and always disposed at right angles to each
other. Between the extreme forms of development of these
and the simple stellate spicula, there is a very great amount
of structural difference ; but on a more intimate acquaint-
ance with the intermediate forms, we find them passing
into each other so gradually as finally to connect the whole
into one group.

It is not in the Spongiadae only that these singular and
beautiful organs are found. In the soft parts of the
extensive family of the Gorgoniadae they are in vast
abundance, and in every variety of form, from an elongate
tubercular spiculum to the elon go-stellate forms of the
Spongiadae, and the prevalence of the bluntly terminated
radii is strongly indicative of their non-defensive character.
But this latter quality does not obtain in other cases,
either as regards the higher tribes of animals or the Spon-
giada3. Thus we find in numerous species of compound
tunicated animals their fleshy substance is crowded with
sphero-granulate spicula, very closely resembling in form
those of the sphero and subsphero-stellate shapes so abun-
dant in Tethea Ing alii and T. robusta (Figs. 164 and 165,
Plate VI). In both these cases the acute termination and
the peculiarities of their respective situations are indicative
of their subserving the office of defensive, as well as that of
consolidating spicula.

Simple Stellate Spicula.

Stellate spicula are composed of few or many radii
emanating from a centre in all directions. Their simplest
form is when the bases of the radii all proceed from a
common central point (Fig. 158, Plate VI), in which case
they should be designated simply, stellate spicula ; but

52 ANATOMY AND PHYSIOLOGY

when the radii spring separately and distinctly from a
common central spherical or oval base, they should be
designated sphero-stellate spicula (Figs. 162, 164, 165,
166, 167, Plate VI). In both these classes of spicula there
is a very considerable difference in their size and form, in
the various species of sponges in which they occur.

Compound Stellate Spicula,

The curious and beautiful forms of this series of spicula
all belong to the class of sponges that have a skeleton
composed of siliceous fibre, and they are principally from
tropical climates. The central basal structure from which
the radii are projected, in every case with which I am
acquainted, is a rectangulated hexradiate spiculum, from
the apices of which a variety of beautiful terminations are
projected, which vary in form exceedingly in different
species of sponges. In the class of sponges to which I
have alluded there are also numerous rectangulated spicula,
varying in the nu-mber of radii from three to six, the
apices of the radii being either acutely terminated or more
or less elevated, and these forms vary very much in size.
They are unconnected with the skeleton, and evidently
belong to the Sarcodous system of the sponge. They are
very much larger than the hexradiate centres of the com-
pound stellate spicula, but as they are evidently the normal
forms of that tribe, I shall describe the general characters
of these large, simple, hexradiate forms before those of the
more complicated stellate ones.

Attenuated rectangulated hexradiate (Fig. 174, Plate
VII.) — The first state in which we find them is in
that of an inequi-acerate spiculum (Fig. 175), in which
condition they are in fact the two axial radii of the
hexradiate form which they ultimately attain when in
their fullest state of development. In the next stage we
find a bud-like projection issuing from the side of the
thickest portion of the inequi-acerate spiculum (Fig. 176),
which is ultimately developed in the form of a rectan-
gulated triradiate spiculum, as in Fig. 179. Or two buds

OF THE SPONGIAD^E. 53

are simultaneously projected, as in Figs. 177 and 178, and
the result is a regular rectangulated quadriradiate form, as
in Fig. 181. Or if the second ray be at a right angle to
the one first projected, the result is an irregular quadrira-
diate figure, as represented by Fig. 180. In like manner
the irregular pentradiate form arises from the absence of
one of the four secondary rays, as in Fig. 182; or it some-
times occurs that the apical portion of the inequi-acerate
axial spiculum is deficient, and the result is, as represented
by Fig. 183, a regular pentradiate form. If the whole
of the radii are equally produced, the result is then the
regular attenuated rectangulated hexradiate spiculum,
(Fig. 174.)

Sometimes, but rarely, we find a single ray more or
less spinous at its distal end ; in this case it is probable
that it was attached by that point to the membranous
structure, or to some part of the keratode of the
skeleton.

The whole of these interesting spicula were obtained
from Mr. Cuming's specimen of Euplectella aspergiUum,
Owen. They are abundant in that sponge, frequently
filling up the interstices of the network of the siliceous
skeleton, or otherwise entangled in the tissues. hi
Dr. A. Farre's specimen of Euplectella cucumer, Owen,
they are equally abundant, and are not to be distinguished
from those in Mr. Cuming's specimen. They are, like
the great external prehensile spicula, and the fibre of
the skeleton, composed of numerous concentric layers of
silex, which readily separate from each other by decom-
position.

I cannot say with absolute certainty that this tribe
of spicula belong really to the sarcode, as I have never seen
specimens of either of the species I have named, in which
they occur in profusion, in such a state of preservation
as to allow of their position being positively determined ;
but as in another specimen of sponge with a siliceous
skeleton like that of Dactylocalyx pumicea, Stutchbury,
the sarcode is preserved in excellent condition, and occurs
in such abundance, filling all the interstices of the skeleton

54 ANATOMY AND PHYSIOLOGY

of the sponge, and affording ample space for the imbed-
ment of such spicula in its substance, I am, therefore,
induced to think it probable that a similar abundance
of sarcode may exist in Dadylocalyx and other similarly
constituted sponges, and that hereafter even the largest
of this tribe of spicula will be found completely imbedded
in the sarcode.

Slender attenuated rectanyulated hexradiate (Fig. 184,
Plate VII). — Beside the large and stout attenuato-
hexradiate spicula in EuplecteUa asperyillum, there are
comparatively small and very slender ones, many of which
are nearly of the same proportions as the larger ones ; but
generally speaking the axial radii are more elongated,
and in some cases the basal end is extended to four
or six times the length of the apical portion.

These spicula do not present the same irregularity in
their development that we observe in the stout ones,
and it is a rare occurrence to find one without the full
number of rays. They are exceedingly numerous in the
sponge, and they occur in closely packed fasciculi, the
axes of the spicula nearly touching each other. Amidst
these fasciculi we find the large stout forms imbedded, the
whole of them apparently having been completely enveloped
by the sarcode of the sponge.

Cylindro-rectangulated hexradiate : apically spined (Fig.
185, Plate VII). — This form is very abundant in an
un described species of AlcyonceUum in the Museum of
the Jardin des Plantes, Paris. The figure represents
the upper portion of the spiculum only, the lower portion
of the axial shaft being exceedingly elongated. When
examined with a power of 400 linear, the apices of the
radii are seen to be abundantly, but minutely spined.
The axial shaft of this spiculum, without any of the lateral
radii developed, is also abundant ; it is exceedingly long,
and at the proper distance below the apex we often observe
a gradual enlargement of the diameter, as represented in
Fig. 187, and the rudimentary canals for the lateral radii
are frequently apparent.

This form of spiculum is also very abundant in Dae-

OF THE SPONGIAD^l. 55

tylocalyos pumicea, Stutchbury, Iphiteon of the French
Museum. In general character they are very similar to
those of the Alcyoncellum described above, with the addition
of the apices of the radii being more or less elevated.

All the simple rectangulated hexradiate forms of spicula
hitherto described are large compared with the rectan-
gulated hexradiate spicula which form the central bases of
the compound stellate forms, and excepting the disparity
in size, the transition from the last form described, to the
complicated and beautiful compound stellate ones, is easy
and natural ; the apices of the hexradiate form becoming
the bases of the numerous radii of the stellate ones. This
transition from the simple to the compound forms is
admirably illustrated in a bifurcated spiculum that occurs
in the new species of Alcyoncellum in the Museum of the
Jardin des Plantes. This form I have designated bifurcated
rectangulated hexradiate stellate, represented by Fig. 188,
Plate VIII. The next stage of development is when we
find each ray of the simple rectangulated hexradiate
spiculum terminated by either three, four, or eight symme-
trically disposed spicula, as represented by Figs. 189, 190,
191, and 192, Plate VIII, and their terminal secondary
radii are either acute or spinulate.

A still further amount of development is apparent in
the beautiful Floricomo hexradiate form represented by
Figs. 193 and 194, Plate VIII.

The central radii consist of six rectangulated primary
rays of equal length, with slightly expanded terminations,
from each of which there issues seven or more petaloid
secondary spicula, the whole forming one of the most
beautiful simulations of a flower imaginable.

Each petaloid spiculum is slender at its proximal termi-
nation, and continues to be so until near its distal end,
where it expands laterally, and presents a nearly semi-
circular concavo-convex termination, with a beautiful
dentate margin, the number of the dents being usually
seven. Each of the petaloid spicula curves gently outward
from its base, the flowing line returning towards the
central axis of the flower at about half of its height from

56 ANATOMY AND PHYSIOLOGY

the base, and then it again curves outward, until the
apical expansion is at right angles to the floral axis ; so
that the whole resolves itself into a form like that of the
flower of a Jasmin. The beautiful terminal petaloid
expansions, with their regularly disposed marginal dents,
renders the illusion complete ; the united basal curves
looking as if they had been produced by the swelling
ovarium of a flower.

I have obtained a considerable number of these elegant
spicula from my friend Mr. Cuming's beautiful specimen of
Euplectella aspergillum, Owen, which, with his accustomed
liberality, he placed at my disposal for examination. They
are found also in Dr. A. Farre's specimen of Euplectella
cucumer, Owen, agreeing in every respect with those from
Mr. Cuming's sponge.

Generally speaking, the slender rectangulated hexradiate
spicula occur singly, but I have sometimes found them
grouped together; in this case their axes were coincident
and their radii in the same plane, or very nearly so, but not
always agreeing in their direction ; such a framework would
form a very fitting support to a large mass of sarcodous
tissue partially separated from the framework of the skeleton
and occupying a portion of a large interstitial space.

In the large open areas of the skeleton of Euplectella
aspergillum, Owen, the hexradiate forms, ranging from
Figs. 174 — 183, Plate VII, are exceedingly abundant, and
a considerable number of them are not developed to
the extent of the full number of their radii. This mav

i/

probably arise from the development of the radii being
stimulated bv the necessities of the mass of sarcodous

V

tissues in which they are imbedded, and consequently
where no necessity for their presence exists they would
not be put forth. In the trifurcate and quadrifurcate
hexradiate forms, if we may judge from the termination
of their radii, they, like the simple stellate forms, are either
purely consolidating, or they combine with that office that
of defensive spicula also, as far as regards the sarcodous
substance in which they are imbedded.

We can scarcely imagine any defensive properties in the

OF THE SPONGIAD.E. 57

slender and complicated but elegant forms of the floricoino-
stellate spicula, and it is probable that their office is purely
that of assisting in the consolidation of the sarcodous
substance.

The whole of these beautiful stellate forms of spicula are
siliceous, while their homologues in the Gorgoniadae and
the compound tunicata are calcareous ; and it is somewhat
remarkable that hitherto none of these forms have been
found in the calcareous species of sponges.

Spicula of the Ovaria and Gemmules.

We find the same laws in force regarding the spicula in
the structure of the minute bodies which have been
designated gemmules by previous writers on the Spongiadse,
that obtain in the sponges themselves. In some they
serve the purposes of internal skeleton and defensive
spicula as well. In others they combine the offices of
tension aud defensive organs, and frequently they are very
different in form from those of the parent sponge. They
occur in various modes of disposition.

1. Those which have the spicula disposed at right angles
to lines radiating from the centre of the ovarium to its
surface.

2. Spicula disposed in lines radiating from the centre to
the circumference of the ovarium.

3. Those having the spicula disposed in fasciculi in
the substance of the gemmule from the centre to the
circumference.

In the first mode of disposition they are sometimes
of the same form as those of the skeleton, but considerably
less both in length and diameter, to adapt them to the
office they have to perform. In other cases they differ
materially in both size and form from those of the
surrounding skeleton ; but in every case with which I
am acquainted, their long axes are parallel to the outer
surface of the case of the ovarium, or to the surface of
the ovarium itself.

In the second mode of disposition they are immersed in

58 ANATOMY AND PHYSIOLOGY

the comparatively thick crust of the ovarium, their long
axes being always at right angles to lines radiating from
its centre to its circumference. Their forms become
widely different from those of the skeleton spicula, and
especially adapted to their peculiar office ; and their
terminations frequently expand into broad plates, as in
Sponyilla Jluviatilis, Johnston. Their forms vary con-
siderably in shape and structure in different species. In
the ovaries of some sponges, one of these modes of the
disposition of their spicula only can be observed.

In the third mode of arrangement, where the spicula
abound in every part of the gemmule, as in Tethea cranium,
Johnston, they are various in form, but resemble to a
considerable extent those of the skeleton, with an inter-
mixture of forms peculiar to the gemmule.

In ftpongilla Carteri, Bowerbank, and S. Jluviatilis,
Johnston, our commonest British species, belonging to the
first group, the external series of spicula of the ovaria are of
the same form as those of the skeleton, but frequently
somewhat shorter. They are disposed irregularly over the
surface of the ovarium, and firmly cemented to it by
the middle of the shaft, while each of their apices are
projected in tangental lines. Thus their shafts perform
the office of tension spicula, while their terminations
become efficient weapons of defence. Fig. 201, Plate IX,
represents the spiculum of the ovary of $. Carteri.

In other cases in this group we find these spicula
differing from those of the skeleton of the parent sponge ;
thus the one represented by Fig. 203, Plate IX, from the
surface of Spo ng ilia lacustris, Johnston, is curved so as
to accommodate it to the rotundity of the ovary (Fig. 320,
Plate XXII), and we do not find its apices projecting
as in those of S. Jluviatilis, but instead of the projecting
apices, the whole spiculum is covered with minute spines,
assimilating it in character with the general structure
of those spicula which combine the office of tension and
defensive spicula, but differing considerably in their pro-
portion from the tension spicula of the same sponge,
S. lacustris, represented by Fig. 90, Plate IV, the one

OF THE SPONGIAD^E. 59

being evidently destined to sustain and protect extended
membranes, while the other is especially adapted for a
small curved surface by its form and small size ; each of
the figures being drawn with the same power, 660
linear.

On the surface of the ovarium of Spongilla cinerea,
Carter, we find this description of spiculum still more
decidedly produced. It is of a cylindrical form and
entirely spined, and has just the amount of curvature that
is in unison with the surface on which it reposes. The
spines on the middle of the shaft are cylindrical, and
terminated bluntly so as to strengthen its hold on its
imbedment. Those of its apices, on the contrary, are
acutely conical and recurved, and are strongly produced so
as to form very efficient weapons of defence. This spiculum
is represented by Fig. 207, Plate IX.

The birotulate and boletiform spicula of the second
group appear to be more purely structural, as regards
the skeleton of the ovarium. The rotulae are very closely
packed at both the external and internal surfaces of that
body, and the crenulation or dentation of each rotula is as
well produced on the internal as on the external ones, and
it appears to be very influential in maintaining each
spiculum in its proper position. In the natural condition
of the ovaria these spicula are entirely imbedded in its
walls, and other spicula of a truly defensive nature are
superimposed for its protection. The large spine in the
shafts of the birotulate spiculum from Spongilla plumosa,
Carter (Fig. 208, Plate IX), are also apparently subservient
to strengthening and maintaining the spiculum in its
proper situation, although they are acutely terminated, as
defensive spines usually are ; but in the same relative
position on the birotulate spicula of ftponffilla Meyeni,
Carter, we find the spines short, stout, and cylindrical,
spreading or budding at their apices, and evidently more
fitted for assisting to retain the spiculum in its proper
place than for defensive purposes. This spiculum is repre-
sented by Fig. 219, Plate IX.

There is an apparent analogy between the expansions of

60 ANATOMY AND PHYSIOLOGY

the rotulae and those of the foliato-peltate spicula, but they
do not appear, like the latter, to be derived from the
ternate forms. The radiation of the canaliculi, as repre-
sented by Pig. 222, Plate IX, are not derived from three
primary rays, but each appears to emanate from a central
cavity at the end of the shaft; and their number, 22,
at their proximal termination, is not reconcilable with any
regular number of bifurcations arising from three primary
rays, however short we may imagine them to be.

The progressive decline of the inner rotula in the inequi-
birotulate spiculum of Sponyilla paulula, Bowerbank (Pig.
221, Plate IX), and its all but total extinction in SpongiUa
reticulata, and Sponcjilla recurvata, Bowerbank (Pigs. 223
and 224), until the distal rotula merges in the scutulate
form, with an acute external umbo in place of an internal
shaft as in Spongilla Brownii, Bowerbank, Figs. 226 and
227, exhibits a very interesting series of gradations of
development in the same description of organ.

The whole of this beautiful group of spicula occur in
the thick coriaceous proper coat of the ovaria of the Spon-
gillidae. Sometimes we have but one form thus located, as in
Spongittajluviatilis, Johnston, where we find them very close
together in the case of the ovariurn, as in Pig. 318, Plate
XXII, the outer rotula supporting the external membrane,
and the inner one performing the same office for the internal
one, as represented by Pig. 319, Plate XXII. At other times
we find two distinct forms in the coat of the ovarium, as in
Spongilla recurvata, Bowerbank, from the River Amazon ;
the inner one being slender boletiform (Pig. 224, Plate IX),
and the outer one multihamate birotulate (Fig. 220,
Plate IX). In every case these spicula are so completely
immersed in the thick coriaceous coat of the ovarium, that
they are perfectly invisible under ordinary circumstances ;
and it is only after the ovary has been boiled in nitric acid
for a very short period, that it is rendered sufficiently
transparent to allow of the spicula being seen in situ.

The progressive development of these forms of spicula is
very beautifully exhibited in the spicula from the ovaria of
Spongitta plumosa, Carter. We first observe them, with a

OF THE SPONGIAD^l. 61

linear power of 660, in the shape of slender, smooth,
cylindrical spicula, with a slight enlargement at each ter-
mination, and without the slightest indication of spines on
the shaft ; and in this condition the central cavity is large,
occupying about one third of its diameter (Fig. 210,
Plate IX). In the second stage, the only alteration in its
form is an enlargement of the terminations, the edges
assuming an angular shape, and a few slender spines are
observable (Fig. 211). In the third stage of development
the terminations assume the form of distinct circular plates
or incipient rotulaB, the margins of which are slightly
crenate ; the shaft exhibits numerous long slender spines,
and the central cavity now does not occupy more than one
fifth of the diameter of the spiculum (Fig. 212). From
this form specimens in every stage of development may be
readily traced, until the strongly spinous margin, the pro-
minent convexity of the rotulse, and the robust shaft with
its long conical spines, indicate the completely adult con-
dition of the spiculum, and in this state the central cavity
can very rarely be seen (Fig. 208).

The growth of these spicula in their early stages is
probably very rapid, as the number of those in the first
and second stages is remarkably small as compared with
those in the third and subsequent stages.

In the inequi-birotulate spicula of Sponyilla paulida,
Bowerbank, we find a number of radial canals passing
from each end of the central cavity of the shaft to the
extreme circumference of the rotulse ; and it is therefore
probable that this expanded part of the spiculum is similar
in character to that of the foliato-peltate spiculum which I
have described (Terminology, 102) in treating of the
spicula of the membranes ; and that they are, in fact,
originally composed of a series of terminal radial spicula
expanding and coalescing laterally, and thus forming one
plane circular surface in place of numerous separate
radii (Fig. 222).

The spicula of the third group, those having the spicula
disposed in fasciculi in the substance of the gemmule, differ
less in character from those of the parent sponge than

62 ANATOMY AND PHYSIOLOGY

those of either of the preceding groups. They are in
reality but modifications of the external defensive spicula of
the parent sponges.

The inequi-fusiformi-acerate one (in the Gemmule of
Tethea) differs from the fusiformi-acerate one of the
skeleton in no other respect than in the greater propor-
tionate attenuation towards its distal termination, which
gives it a degree of flexibility that allows of its bending
freely under the pressure of any comparatively large body ;
and I have seen them, when two gemmules have been
pressed closely together, bent to the extent of semicircles
without breaking. In the young gemmules these spicula
are usually projected much beyond the other forms of
defensive spicula that accompany them.

In like manner the small attenuato-porrecto-ternate
form in the same gemmule is a modification of the similarly
formed external defensive spicula of the parent sponge.
In the adult gemmule the apices of these spicula rarely
project beyond the dermal membrane, and it is only on
pressure from without that they would be brought into
effective use. The amount of the angle of their radiation
at the apex of the spiculum is therefore greatly increased
beyond those of the external defensive ones of like form in
the parent sponge, so as to accommodate their apices to
the curve of the surface of the gemmule, and to render
each point equally effective ; and as they are not projected
beyond the dermal surface, as in the sponge, their shafts
are shortened proportionally.

The unihamate, bihamate, and recurvo-ternate forms of
the same gemmules are also modified forms of the recurvo-
ternate external defensive spicula of the parent sponges,
Tethea cranium and similima.

KERATODE

Is the substance of which the horny elastic fibres of the
skeleton of the officinal sponges of commerce are composed.
It has, correctly speaking, no relationship either chemically

OF THE SPONGIADJ3. 63

or structurally with horn, and Dr. Grant has judiciously
rejected the term " horny fibre" as applied to the sponges
of commerce, and has substituted that of keratose by way
of distinction ; and in accordance with that term I propose
to designate the substance generally as keratode, whether
it occurs in the elastic fibrous skeleton of true Spongia,
which are composed almost entirely of this substance, or of
those of the Halichondraceous tribe of Spongiadae, where
it is subordinate to the spicula in the construction of the
skeleton, and appears more especially in the form of an
elastic cementing medium. In a dried state it is often
extremely rigid and incompressible, but in its natural
condition it is more or less soft, and always flexible and
very elastic. It varies in colour from a very light shade to
an extremely deep tint of amber, and it is always more or
less transparent. In its fully developed condition, in the
form of fibre, it appears always to be deposited in con-
centric layers ; but in the mode of the development of
these layers there are some interesting variations from
the normal course of production. As we find in Aranea
diadema, the common Garden Spider, that the creature has
the power of modifying the deposit of the substance of its
web so that the radiating fibres dry rapidly while the
concentric ones remain viscid for a considerable period, so
we find in the production of the young fibres of the
skeletons of the Spongiadse in some species, as in those of
commerce, there is no adherent power at the apex of the
young fibre, excepting with parts of its own substance;
while in Dysidea, and in some other genera, the apex of the
newly-produced fibre is remarkably viscid, adhering with
great tenacity to any small extraneous granules that it may
happen to touch in the course of its extension (Fig. 272,
Plate XIV) ; but this adhesive character appears to be
confined to the earliest stages of its production only, as
exhibited at the apices of the newly-produced fibres, the
external surface immediately below the apex exhibiting no
subsequent adhesive property.

Lehman, in his ' Physiological Chemistry,' Cavendish
Society's edition, vol. i, p. 401, states that Spongia officinalis

64 ANATOMY AND PHYSIOLOGY

of commerce consists of 20 atoms of fibroin, 1 atom of
iodine, and 5 atoms of phosphorus ; and in treating of the
physiological relations of fibroin as regards sponges, he
observes, " Its chemical constitution affords one of the
arguments why the Spongia should be classed among;
animals and not among plants, since in the vegetable king-
dom we nowhere meet with a substance in the slightest
degree resembling fibroin."

From the general physiological characters of the skeletons
of the Sertularian and other Zoophytes, I had long suspected
that their component parts were identical, or very nearly
so, with those of the skeletons of the Spongiadse, and
I therefore applied to my friend, Mr. George Bowdler
B nekton, to assist me in determining this point, and he
very kindly undertook to make comparative qualitative
analyses with two species of Zoophytes, Sertularia oper-
culata and Flustra foliacea, with the fibres of Spongia
officinalis and of raw silk, and I cannot do better than
to quote entire the report of the results of his exami-
nation :

" I have examined the Zoophytes you sent me, and
have compared their deportment under chemical agency,
with that shown by white silk and the fibre of ordinary
sponge.

" All the specimens were treated in a similar manner,
being purified from foreign matter, as far as possible, by
boiling for two hours in water, and subsequently for the
same period in strong acetic acid. With the exception of
Flustra, the substances exhibited by this treatment little
change in their outward appearance. Carbonate of lime
enters so largely into the composition of Flustra, that its
disintegration by acids ought to cause no surprise.

"From the results of the first seven experiments,* I
conclude that all these bodies contain the same, or a very
similar animal principle, which I suppose to be identical
with Mulder's fibroin. The varying colours of the pre-
cipitates from tannic acid and ammonia, I think is probably

* Fora table of the results of the analysis of Mr. Bucktou, sec 'Philo-
sophical Transactions ' for 1863, page 740.

OF THE SPONGIAD.E. 65

due to the traces of sesquioxide of iron present in the
fibres, and the difference in shade is simply caused by the
greater or less preponderance of that metal.

"Although I have not been able to obtain fibroin in
a state of chemical purity, I would state that, to my
knowledge, there is no vegetable principle which behaves
itself towards reagents in a manner similar to that shown
by the substance of silk, sponge, &c.

" Mulder and Crookewit's analyses show silk and sponge
scarcely to differ in composition.

Fibroin
from Silk.

Carbon 48'5

Hydrogen . . Pr5

Nitrogen . . 17'3

Oxygen 1

Sulphur }• . . . 27'7

&c. &c. J

100-0

Fibroin from

Sponges.

Carbon . 46'5 to 4S'5

Hydrogen . . 6'3 Cv3

Nitrogen . . lf,-l Ifrl

Oxygen
Sulphur
Phosphorus
Iodine

31-1 29-1

100-0 100-0

Schlossbcrger has recently expressed his doubts of the
identity of composition of these bodies, from the cir-
cumstance that silk is readily soluble in strong ammonia,
saturated with oxide of copper, whilst sponge is scarcely, or
not at all, affected by long maceration. My own expe-
riments prove the same fact, yet it is not impossible that
the minute quantities of iodine, phosphorus, and sulphur
present in sponge may modify the solubility of the
fibre.

" Under the supposition that a resinous gum might act
as a protection, portions of sponge were boiled in benzol,
ether, and alcohol, but these solvents did not modify the
characters in any noticeable degree.

" I consider, however, that this difference between
sponge and silk in no wise affects the question of the
former substance being a product of the animal kingdom,
which the other experiments, I think, satisfactorily
prove."

In considering the results of these analyses with a view

5

66 ANATOMY AND PHYSIOLOGY

to proving the animal nature of the Spongiadae, the
evidence afforded by the coincidence of its structural
character and its chemical constituents with those of Sertu-
laria operculata, are still more conclusive than that derived
from the chemical constituents of silk ; and, in truth,
the action of the chemical agents on the zoophyte and the
sponge, as might naturally be expected, are almost in
perfect accordance.

MEMBRANOUS TISSUES.

These structures may be divided into two classes :

1st. Simple membranous tissue.

2nd. Compound membranous tissue.

The first is a simple, apparently unorganized, thin,
pellucid tissue. It is evidently not composed of an exten-
sion of keratode, as it is rapidly decomposed after the
death of the animal. It is found in abundance filling up
the areas of the network of the skeleton in a great variety
of sponges, and it appears to be capable of secreting sarcode
on both its surfaces when thus situated ; on the dermal
membranes the sarcode is found on the internal sur-
face only.

Compound membranous iissties. — These structures con-
sist of simple membranous tissue combined more or less
with primitive fibrous tissue. Their most simple forms
exist in the membranes lining the interstitial cavities of the
sponge, and in the dermal membranes.

It is difficult in some cases to discriminate between this
class of tissues and simple membranes, unless it be by the
aid of their functional characters, as the compound tissues
are frequently quite as pellucid, although not so thin, as
the simple ones.

In dermal membrane, and the membranous linings of
the internal cavities of the sponge, they are thin and
very translucent ; but by a careful examination with high
microscopic powers and transmitted light, with the aid of
polarization, we frequently detect the elastic primary

OF THE SPONGIAD.E. 67

fibrous tissues incorporated with the structure. In the
contractile membranes forming the oscular diaphragms in
Grantia, and in those at the base of the intermarginal
cavities in Geodia and Pachymatisma, they attain a greater
degree of thickness, and especially in the two latter genera
of sponges. In Alcyoncellum, Quoy et Gaimard, the orga-
nization of their tissue is still more complex, and we there
find them constructed of repeated layers of membranous
structure, abounding in primitive fibrous tissue disposed
in parallel lines in each layer, the fibres disposed so closely
together as to completely cover the membrane beneath, and
the direction of the fibres being at various angles to the
axis of the great cloacal appendages of the sponge, so as
most effectually to aid in the contraction or expansion
of that organ. They are so closely packed together and so
intermingled, that I could not ascertain their length but
from the gradual attenuation of some of their terminations ;
they would seem not to be continuous for any considerable
distance. On some of the layers of this compound
membrane the fibres were disposed in an even and con-
tinuous stratum, while in others they were gathered
into broad, flat, parallel fasciculi. When the compound
structure consists of several layers of fibro-membranous
structure, the disposition of the fibres on the different
layers are not coincident. In some cases they cross each
other at right angles, while in others the angle does not
exceed 45 degrees. The latter mode of arrangement
appears to prevail in the membranes connecting the great
longitudinal fasciculi of spicula, forming to a great extent
the skeleton of the cloacal appendages of the sponge ;
while the arrangement at right angles appears also in
the tissues immediately surrounding the great skeleton
fasciculi.

This fibre-membranous tissue abounds in the dermal
and interstitial structures of the sponges of commerce,
but the greatest development of this structure is exhibited
in the genus Stematmuenia.

Fig. 255, Plate XII, represents a small portion of the
lining membrane of one of the great excurrent canals of

68 ANATOMY AND PHYSIOLOGY

the common honeycomb sponge of commerce, in the con-
dition in which it came from the sea. The primitive
fibrous tissue is seen arranged in a single layer in parallel
lines at right angles to the long axis of the canal, but
partially obscured by the stratum of sarcode on the
membrane.

Fig. 256, Plate XII, represents a small portion of
the dermal membrane of a Stematumenift, in which the
primitive fibres are seen wandering in every direction over
the surface of the membrane.

Figs. 257 and 258 in the same plate represent portions
of a stouter and a more compound membranous structure,
from the walls of one of the great cloacal projections from
the surface of Alcyoiiccllum rolmsta, Bowerbank. In this
case the membrane is strengthened by two or more layers
of primitive fibrous structure, the parallel fibres of each
crossing the others at various angles.

FIBROUS STRUCTURES.

There are two well-characterised classes of fibrous
structure :

1st. Primitive fibrous tissue.
2nd. The fibres of the skeleton.

1 . Primitive Fibrous Tissue.

The first of these tissues is exceedingly minute. The
fibres are cylindrical in form, and are usually of considerable
length ; but where they are fully developed, they occur in
such numbers, and in such a matted condition, that I have
been unable to separate an unbroken one from the mass.
They continue through the whole of their length as nearly
as possible of the same diameter, and there rarely appears
to be any attenuation towards their terminations, which are
usually obtuse. They are evidently very elastic and
contractile. When partially separated from their attach-
ments to the membranes, the free ends seldom remain

OF THE SPONGIALLE. 69

straight, and most frequently they curl considerably in
different directions. They appear to be perfectly solid ; I
could not by the aid of polarization discover the slightest
indication of a central cavity. They vary in diameter
in different species of sponge, and frequently so even
in the same individual. In a species of Stematumenia from
the Mediterranean, I measured an average-sized fibre which
was 3^5 inch in diameter, while a smaller one, closely
adjoining, measured ~ inch. In this genus these fibres
are more fully developed and larger in size than in any
other sponges with which I am acquainted. In the
sponges of commerce, in the membranes of which they are
exceedingly numerous, they are much more slender. In one
of the excurrent canals of the common honeycomb sponge,
one of the largest measured Tr,\^, inch in diameter, and one of
the smallest p,^ inch. In the dermal membrane of the
best Turkey sponge they were still less, not exceeding

u;,oou men.

This description of fibre is not an absolutely necessary
constituent of a sponge, and in many of the Halichondrace-
ous tribes it is exceedingly difficult to find even a single
straggling fibre on the interstitial or dermal tissues, while
in other genera, as in JSpotiffia, Stematumenia, and Alcyoii-
cellum, they form an important element in the structure of
the compound membranous tissues, in which they are
closely disposed in parallel lines, occasionally giving off
branches, but never appearing to anastomose with each
other like the larger fibres of the skeleton.

These fibro-membranous tissues were described by me
in the ' Annals and Magazine of Natural History,' vol.
xvi, page 406, plate xiv, figs. 1, 3, 4, and 5, in my
description of the genus Stematumenia.

If a small portion of the dermal membrane of a young
Stematumenia be carefullv removed from the surface of the

t/

sponge, the primitive fibres will be seen projecting from
the edges of the membrane in considerable numbers ; and
occasionally they may be seen to be furnished with a
terminal bulb, the greatest diameter of which is about three
times that of the fibre. The bulbs are variable in form ;

70 ANATOMY AND PHYSIOLOGY

sometimes they are largest at the base, or pear-shaped,
at other times regularly oval, or nearly globular. By far
the greater number of fibres exhibit no bulbs at their
terminations ; those which have them are always less in
diameter than the general average of the fibres. Some-
times, but not very frequently, the bulb exhibits faint
traces of a nucleus. On examining the dermal membrane
by transmitted light and a linear power of 666, I found
numerous globular cells collected in groups on various
parts of its inner surface, many of them having a well-
defined central nucleus ; and among these cells I found the
bulbs imbedded, with the fibres emanating from them, and
in no respect differing in appearance from the non-fibrous
cells around them (Fig. 259, a, a, Plate XII). On carefully
observing a number of these bulbous fibres that had been
removed from their positions on the membrane, I found
that the part of the fibre nearest to the bulb was frequently
flexuous, as if in a tender and immature condition, and in
these cases the marginal line of the fibre was continued
without the slightest break or interruption into and around
the bulb, as represented in Fig. 260, a, Plate XII. At this
period of the development the young fibre does not
measure above half the diameter of a mature one, and there
is no indication of an ultimate separation from the bulb ;
but when the fibre has attained nearly the full size the
separation is then distinctly indicated ; the basal end of
the fibre immersed in the bulb becomes hemispherical, and
a constriction appears at the junction of the fibre with the
exhausted cell. Sometimes, when thus affording indi-
cations of their ultimate separation, the cell still retains its
rotundity, but all indication of its nucleus has disappeared,
and it is perfectly transparent, as represented in Fig. 2 60 A
Plate XII, while in other cases it is visible only as a
collapsed and shrivelled vesicle adherent to the hemi-
spherical termination of the fibre, as represented in Fig.
260, c, Plate XII. I could not find the slightest indication
of bulbs amid the matted mass of fibres lying on the inner
surface of the membrane, and it was only at the torn
edges of the pieces of membrane under examination, or

OF THE SPONGIAD.E. 71

among the groups of cells, that the bulbs in connexion with
the fibres were to be discovered.

This form of fibrous tissue is not essentially a sponge
structure ; it enters largely into the composition of the
niembrana putaminis, and the shell of the egg of the
domestic fowl, arid I have also found it in the foliated por-
tion of a coral, Pavonia lactuca, when deprived of its
earthy matter by dilute hydrochloric acid ; and it occurs
also in the membranes of some species of Ascidians. Prof.
Bowman, in his treatise on mucous membrane, in the
' Cyclopaedia of Anatomy and Physiology/ in his descrip-
tion of the white fibrous element of areolar tissue, says,
" Beside these bands, commonly called fasciculi, there are
some finer filaments of the utmost tenuity, which seem to
take an uncertain course among the rest." These fila-
ments, it is very probable, are the homologues of the
primitive fibrous tissue which I have thus described.

2. Keratose Fibrous Tissue.

General character of the keratose fibres of the horny
skeleton. — The essential character of the fibres of the horny
skeleton is, that their normal form is always that of a cylinder,
while the network of the skeletons of the Halichondroid
sponges, which approach nearest in structure to that of
spiculated keratose fibre, is always more or less irregular
in shape ; and in the fully developed state generally com-
pressed to a very considerable extent ; but a careful exami-
nation of the youngest portions of the two forms of skeleton-
tissue will always render the difference in the two structureb
apparent. In the spiculated keratose fibre the keratode is
always the predominant element, and the spicula the sub-
ordinate one ; while in the skeletons of the Halichondroid
sponges the spicula always predominate, and the keratode
is merely the secondary or surrounding medium. In the
former structure, in the extension of the terminations of
the skeleton, the keratode is the leading element, while in
the latter the spicula take the lead.

The fibre is formed of a succession of concentric layers,

72 ANATOMY AND PHYSIOLOGY

its increase in diameter being apparently effected at the
external surface. Its longitudinal extension appears to be
caused by a progressive elongation of their terminations,
and new fibres are frequently to be seen pullulating from
the sides of the mature ones. In the dried state it is often
extremely rigid and incompressible, but in its natural con-
dition, notwithstanding there is frequently an internal axis
of extraneous matter or of spicula, it is often remarkably
soft and flexible. The spicula, although immersed in the
fibre, evidently possess a considerable amount of mobility
within the surrounding medium.

The colour of the fibres is always amber-yellow, varying
in different species from a very light to a deep yellow-brown
tint, and it is always semi-transparent. In the living state,
when the fibres happen to touch each other, whether by
their terminations or laterally, they appear at all times to
unite.

The keratose skeleton-fibres vary in their organization to
a very considerable extent, but the whole of them may be
comprised in the following nine typical forms :

1. Solid simple keratose fibre.

2. Spiculated keratose fibre.

3. Hetro-spiculated keratose fibre.

4. Multi-spiculated keratose fibre.

5. Inequi-spiculated keratose fibre.

6. Simple fistulose keratose fibre.

7. Compound fistulose keratose fibre.

8. Regular arenated keratose fibre.

9. Irregularly arenated keratose fibre.

1 . /Solid Simple Keratose Fibre.

The typical form of this description of fibre is that which
forms the skeleton of the Turkey sponges of commerce, the
structure of which I described in a paper read before the
Microscopical Society of London, and published in vol. i,
p. 42, of its ' Transactions.' The mature fibre is perfectly
solid, and no vestige of a central cavity can be observed in
any part of it, either when viewed by transmitted light or

OF THE SPONGIAD.E. 73

in transverse sections of the fibre, by the aid of a Lieber-
kuhn. Occasionally, but very rarely, I have seen in young
and immature fibres faint and irregular indications of there
having been a very small central cavity in perhaps the
earliest period of its development, but in the mature fibre
I have never been able to trace such cavities (Fig. 201,
Plate XIII).

This description of fibre is occasionally surrounded by a
membranous sheath, on which is imbedded a beautiful
system of hollow fibrils or vessels, which sometimes wind
round the skeleton-fibre in a spiral direction ; at others it
assumes a longitudinal course, giving off" short csecoid
branches ; or it forms a complex and irregular network.
In an Australian sponge in my possession, the latter mode
is the only form in which it occurs. In some of these
minute fibrils or vessels I observed numerous minute
globules, which were rendered movable by a slight pres-
sure on the glass under which they were exhibited. The
mean diameter of these tubes or vessels was — inch. This
tissue is of rare occurrence, and I have been unable to de-
termine whether it is a specific character, or whether it is
due to a peculiar condition of the sponge. Fig. 279,
Plate XVI, represents a portion of fibre from the skeleton of
one of the sponges of commerce. Fig. 2SO, Plate XVI, is
from a rigid species of Australian sponge. This singular
tissue is described more fully in a paper which I read
before the Microscopical Society of London in 1841, and
which is published in their ' Transactions,' vol. i, p. 32,
plate iii.

2. Spiculated Keratose Fibre.

This structure is essentially a solid form of keratose
fibre, no central cavity ever being visible in its axis. The
normal form of the fibre is cylindrical, but it is occasionally
more or less compressed, and always contains a thin central
line or axis of spicula arranged in longitudinal series. The
spicula are secreted within the fibre, and are nearly uniform
in size, and always of the same shape in the same species

74 ANATOMY AND PHYSIOLOGY

of sponge. In the production of the young fibres, the
projection of the new keratode and the secretion of the
new spicula appears to be simultaneous. In this class of
structure the keratose fibre is the predominant element,
and the spicula the subordinate one, and we accordingly
frequently find the fibres destitute of spicula for short dis-
tances ; but these occurrences are the exceptions, and not
the rule of the structure. Fig. 262, Plate XIII, represents a
portion of a longitudinal section of the skeleton of Hali-
c/tondria oculata, Johnston (Chalina, Bowerbank).

The mode of the progressive development of this form of
fibre is interesting. In a young specimen of Chalina
Montayid, Bowerbank, I observed that when a new fibre
was projected from the skeleton it usually contained a
single spiculum, thinly covered by keratode at the apex,
and more thickly so towards the basal end. Another

i/

spiculum followed the first, the terminations of each over-
lapping the other; and at the junction of the two the
keratode was accumulated in the form of a plumber's joint,
as represented in Fig. 263, Plate XIII, so as to give additional
strength to the junction of the spicula, while the middle
portion of the second spiculum remained very thinly
covered by keratode. When the distal end of the new
fibre has attained its proper length, or has become cemented
to the side of another fibre, the remaining portion of the
keratode is produced, and the fibre then assumes a regular
cylindrical form.

3. Hetro-spicidated Keratose Fibre.

This form of fibre has a somewhat irregular axial series
of spicula, with occasionally exter-axial ones disposed in
accordance with the axial spicula, and others at intervals at
right or nearly right angles to the axis of the fibre. The
only sponge in which I have found this form of fibrous
tissue is Diplodemia vesicula, Bowerbank, from deep water,
Shetland. Fig. 273, Plate XIV, represents a portion of a
skeleton-fibre.

OF THE SPONGIAD^E. 75

4. Multi-spiculaled Keratose Fibre.

This description of fibre is literally a cylindrical mass of
spicula cemented together by keratode, and surrounded by
a thin case of the same substance. The spicula are
exceedingly numerous, and very closely packed in parallel
lines in accordance with the axis of the fibre. They are
nearly uniform in size, and always of the same shape in the
same species of sponge. In this structure the spicula are
the predominant element, and the keratode the subordinate
one. Fig. 264, Plate XIII, represents a fibre from the
skeleton of Desmatidon agayropila, Bowerbank.

5. Inequi-spiculated Keratose Fibre.

This form of fibre is composed of an infinite number of
spicula disposed in every possible direction, cemented
together by keratode, and surrounded by a sheath of the
same material. The spicula agree in form in all parts of
the sponge, and are nearly of the same size. In these
fibres the spicula are the predominant element, the keratode
the secondary one. In the only sponge in which this form
of structure has yet been found, Bapltyrus Griffithsii,
Bowerbank, the fibre is very unequal in size and much
varied in its form, frequently becoming very much flattened
and expanded. Fig. 265, Plate XIII, represents a longi-
tudinal section of a small portion of a fibre from the
skeleton, showing the irregular disposition of the spicula
within it.

6. Simple Fistulose Keratose Fibre.

This form of fibre is usually very much larger and more
rigid than the solid keratose fibre. It is cylindrical, and
continuously fistular. The great central cavity of the fibre
usually occupies about one third of its diameter. It is
nearly uniform in its size, but occasionally it is dilated
considerably for a short space, and then resumes its original

76 ANATOMY AND PHYSIOLOGY

diameter. In the young state the cavity is as large, or
nearly so, as in the adult fibres, while the enveloping
keratode assumes the form of a thin, transparent, amber-
coloured coat, which in the mature state becomes frequently
twice or three times the thickness of the diameter of the
central cavity.

This great fistular space is lined with a thin pellucid
membrane, which, in specimens that have been dried,
appears to have been thickly covered with minute semi-
opaque granules. At the time of my first description of this
form of fibre, published in the ' Annals and Magazine
of Natural History/ vol. xvi, p. 403, I believed that in
the natural condition of the fibres the central cavity was an
open tube, but subsequent observations on specimens which
have never been dried have led me to the conclusion that
the whole of the central space is filled with a minutely
granulated substance, which presents all the characteristics
of sarcode.

There is no communication between the great central
fistular canal and the interstitial cavities of the sponge, the
projecting ends of the fibres of the skeleton being always
hermetically sealed. Eig. 2G6, Plate XIII, represents a
fibre from the specimen of Spongia Jistidaris, Lamarck, in
the Museum at Edinburgh, given to me by Prof. Grant.

7. Compound Fist dose Keratose Fibre.

In its external characters this description of fibre is not,
under ordinary circumstances, to be distinguished from
the simple fistulose fibre, and it is only when submitted to
a microscopical power of about 100 linear that its peculiar
character can be detected. We then find that the fibre is
not only furnished with a large continuous central cavity,
but that it also has numerous minute caecoid canals
radiating from the central one at irregular distances, at
nearly right angles to its axis. These secondary canals are
very unequal in length, and very few of them reach to near
the external surface of the fibre, and none of them appear
to perforate it. Their direction is usually in a straight

OF THE SPONGIAD.E. 77

line from the parent canal ; a few assume a tortuous
direction, and a still fewer number bifurcate or branch.
Within the central tubes of the fibres there are frequently
one or two minute simple tubular fibres ; when more than
one they do not unite, but they divide and traverse each
a separate cavity, when they happen to reach one of the
anastomosing points of the great skeleton-fibre. The
structures are described more at length in the ' Annals and
Magazine of Natural History,' vol. xvi, p. 405, under the
head of " AulisMa" a new genus of sponges, founded prin-
cipally on the compound fistulose structure of its skeleton-
fibres. Kg. 2G8, Plate XIV, represents a portion of com-
pound fistulose keratose fibre as seen with a linear power
of 100. Fig. 267, Plate XIII, a portion of a similar fibre
under a power of 300 linear.

8. Rec/ ii Jar Area tiled Keratose Fibre.

This description of fibre under ordinary circumstances
has very much the appearance of simple fistulose fibre, but
when examined by transmitted light with a linear power of
about 100 we find in the centre of the fibre a series of
grains of extraneous matter, occupying the place of the
large continuous canals of the fistulous forms of fibre.
The series of extraneous matters is not always con-
tinuous, and when an interruption takes place the fibre
becomes solid, or faint traces only of a central cavity remains.
The mode of the inclusion appears to be due to the extreme
terminations of the young fibres being viscid, and thus
seizing on any extraneous particles that happen to come
in contact with them. The growing keratode quickly
envelopes them, and, proceeding on its course of extension,
seizes in like manner on other particles of sand or solid
matter, and thus a continuous and regular chain of extrane-
ous material is imbedded in the axis of the fibre, as repre-
sented by Fig. 269, Plate XIV. This description of fibre
is found in a great variety of keratose sponges, and especially
so among the coarse rigid skeletons of the Australian species.
And among the flexible sponges, as represented by Fig. 269.

78 ANATOMY AND PHYSIOLOGY

9. Irregular Arenaied Keralose Fibre.

I have described this form of fibre in a paper descriptive
of two species of Dysidea, read at the Microscopical Society
of London, Nov. 24, 1841, and subsequently published in
vol. i, p. 63, of their ' Transactions.'

The adult and fully produced fibre is frequently half a
line or more in diameter. It is built up in all parts of its
substance, of grains of extraneous matter, each one being
separately enveloped in keratode. The adhesive power in
the young progressing fibre not being confined to its apex
only, its sides also seize upon the surrounding grains of
solid matter, and the keratode speedily passing round and
enveloping them, the whole fibre becomes a solid cylinder
of irregularly imbedded molecules. There is a great variety
of substances imbedded in these fibres, dependent, as a
matter of course, on the amount of material surrounding
them at the period of their development. The skeleton of
Dysidea frayilis, Johnston, a British species very common
on the south coast of England, presents one of the best
types of this form of fibre. And single grains of sand are
frequently to be found among the fibres of the surface of
the sponge, elevated on short pedicels of the rapidly grow-
ing young fibres, sometimes entirely, and at others only
partially, enveloped by the progressing keratode. Figs. 270,
271 and 272, Plate XIV, represent portions of fibre from
the same individual.

This genus of sponges appears, to the best of my
knowledge, to be the only animals that construct an inter-
nal skeleton almost entirely of extraneous matter.

Siliceous Fibre.

This structure is widely different from any of the keratose
fibres which contain either secreted silex in the state of
spicula, or extraneous silex in the form of sand. The
whole substance of the skeleton-fibre consists of solid silex,
secreted and deposited in concentric layers, exactly after

OF THE SPONGIAD.E. 79

the manner of the secretion of pure keratode in the fibres
of the sponges of commerce. When cleansed from the
sarcodous matter by which they are surrounded in a living
state, the fibrous skeleton bears a striking resemblance to
fibres of spun glass, and is quite as pellucid and colourless
as the artificial material, and the dead sponge quite as
brittle. The fibrous skeleton of Dactylocalyx pumicea,
Stutchbury, in its mode of arrangement strikingly resembles
that of one of the sponges of commerce ; it is equally com-
plex and irregular in its structure, and the component
fibres quite as much anastomosed. In that species the
fibres are smooth and cylindrical, but in others they
frequently abound with minute, obtuse, wart-like elevations.

There is every indication in the skeletons that the increase
in diameter, and the extension in length in the fibres, is
effected in the same manner as in the solid keratose fibres.
The free terminations of the young fibres have the same
attenuated but obtuse form, and the pullulation of the
young fibres from the sides of the mature ones is quite as
apparent as in their keratose congeners, but they never
appear to be in the young state, as the keratose ones fre-
quently are, viscid ; and extraneous matters are never
detected at their apices, or on their substance.

There are two distinct forms of this class of fibre :

1st. Solid siliceous fibre.

2nd. Simple fistulose siliceous fibre.

The structure of solid siliceous fibre is very similar to
that of solid keratose fibre. Occasionally there are indica-
tions of a former existence of a minute central canal ; but
in the fully developed fibre this is rarely visible. The
external characters of these fibres vary in each species. In
a new siliceous sponge in the British Museum, designated
by Dr. Gray M'Andrewsia azoica, the fibres are quite
smooth, as represented by Fig. 274, Plate XV. But in
the greater number of species they are more or less tuber-
culated, as in Fig. 275, Plate XV, which represents a group
of fibres from the type-specimen of Dactylocalyx puwicea,
Stutchbury, a portion of which is in the possession of Dr.
J. E. Gray. In other species in my possession the tuber-

80 ANATOMY AND PHYSIOLOGY

dilation is very strongly produced, as represented in a few
fibres of Dactylocalyx Prattii, Bowerbank, MS., Fig. 270,
Plate XV.

Of the second form, simple fistulose siliceous fibre, I know
but one example, and that is the remains of the siliceo-
fibrous sponge, Farrea occa, Bowerbank, MS., on which
the beautiful specimen of Euplectella citcumer, Owen, is
based.

The tabulation of the skeleton-fibre is very similar to
that of some varieties of simple fistulose keratose fibre, but
the central cavities are not so invariably continuous as in
the keratose varieties of fistulose skeleton-fibre. Fig. 277,
Plate XV, represents a small piece of the spinulated simple
fistnlous fibres of the skeleton of Dr. Arthur Farre's speci-
men. The spinulation of these fibres is a remarkable cha-
racter. It is the only case of the production of acute spines
on the skeleton-fibre of a siliceo-fibrous sponge with which
I am acquainted.

Prehensile Fibres.

In the course of my examination of the fibrous skeleton-
tissues, I have found but one instance in which they have
developed prehensile organs to assist in the attachment of
the sponge, and this in a minute siliceo-fibrous species,
parasitical on the base of a specimen of OcuJina rosea, from
the South Sea. In this sponge the basal fibres curve down-
ward in the form of numerous small, nearly semicircular
reversed arches, from the lowest portions of each of which
there is a short stout portion of fibre projected, and at
about the length of its own diameter downwards a ring of
stout prominent bosses, six or eight in number, is produced,
very considerably increasing its diameter at that part ; im-
mediately beneath which the fibre is attenuated to a point.
These singular organs are admirably calculated to penetrate
the porous cavities or fleshy envelopes of the coral, and
thus to securely attach the sponge to its adopted matrix
(Fig. 278, Plate XV).

OP THE SPONGIADvE. 81

CELLULAR TISSUE.

The cellular structures in the Spongiadae are few and
very simple in form. We find no series of conjoined cells
in the body of the sponge, as in vegetable tissues. The
only forms in which true cellular structures occur in the
bodies of sponges, are those of detached spherical molecular
cells, and of discoid or lenticular nucleated cells. The first
forms are found in abundance on the fibres of many species
of the true sponges, and are believed by Dr. Johnston to
be the reproductive organs of that genus. They are very
minute, not exceeding ~m inch in diameter. They are
pellucid, and afford no indications of a nucleus, either single
or multigranulate (Figs. 315, 316, Plate XXII).

Imbedded in the sarcodous stratum on the interstitial
membranes in many of the Halichondroid tribes of sponges,
we frequently find numerous compressed circular cells. In
the greater number of cases they are so translucent as to
readily escape observation even with a tolerably high power;
but in other species, as in Ecionemia acervus, Bowerbank,
MS., a new genus of sponges from the South Seas, in the
collection of the Royal College of Surgeons, and in Hali-
ckondna nigricans, Bowerbank, a British species, these
tissues are developed in a more than usually distinct
condition.

In the first-named sponge they are thickly dispersed on
the surfaces of the interstitial membranes, but without any
approach to order or arrangement. They are decidedly
lenticular in form, with a well-defined transparent nucleus,
which varied in size from about one fourth to three fourths
the diameter of the cell in which it was contained. The
cells varied considerably in size : the largest I could find
was 3355 inch in diameter, and one of the smallest y^ inch ;
but the greater number were about ~ inch in diameter
(Fig. 281, Plate XVI). In Halichondfia nigricam they do
not appear to be quite so convex as in Ecionemia acervus,
nor are they so numerous as in that species, but they are

6

82 ANATOMY AND PHYSIOLOGY

somewhat larger in size; one of the largest measured ~l}
inch in diameter, and a small one ^ inch : they are repre-
sented in situ in Fig. 282, Plate XVI.

The most complete development of cellular structure
exists in the genus Grantia, where we find them lining the
great interstitial cavities of the sponge, as represented in
Fig. 312, Plate XXI, — each, probably, in a natural and
healthy condition sustaining a cilium. The nucleus in each
cell is constantly present, and strikingly apparent when
viewed with a power of linear, as represented in Fig. 314,
Plate XXI. The only instance with which I am acquainted
of a conjoined arrangement of such cells exists in the enve-
lope of the ovaries Q/iSpongilla Carter i, the species described
by Carter in his ' Account of the Freshwater Sponges in
the Island of Bombay,' which that author believed to be
Sponyilla friabilis, Lamarck, but which proves to be a dis-
tinct species, which I have named after its discoverer, as
a slight recognition of the good services he has rendered to
science by his excellent and accurate observations. These
cells may be detected in situ after the envelope of the ovary
has been submitted for a very short time to the action of
hot nitric acid, so as to render the coriaceous envelope
semi-transparent without destroying it. The structure of
its walls is then seen to consist of linear series of cells, six
or eight in length, closely packed together in lines radiating
from the centre of the ovary to its external surface. They
do not appear to be absolutely in contact with each other,
but are usually seen to be separated by a thin stratum of
a transparent substance, probably an indurated membrane
or sarcode. At the surface of the envelope they frequently
appear to be somewhat hexagonal from mutual compres-
sion. I could not detect a nucleus in any of them (Fig. 284,
Plate XVI). Carter and other writers on Spongilla have
designated the granulated forms of the sarcode in those
sponges, " Sponge cells," but I cannot coincide with that
opinion. I have frequently tried in vain to detect a proper
coat of cellular tissue on the Amoeba-like granular masses
into which Spongilla Jluviatilis resolves itself at certain
periods of its existence, and neither in a healthy and active

OF THE SPONGIADjE. 83

condition, nor in a state of partial decomposition, have 1
ever been able to satisfy myself of the existence of a sur-
rounding membrane. It appears to me that these bodies
are the result of a natural resolution of the sarcode into
granular masses of various sizes, each of which, on being-
liberated from the parent body, becomes an independent
gemmule, which is capable of reproducing the species of
sponge from which it emanates. And I have long suspected
that the Aincebae found in ponds and rivers, and also in
sea-water, are not in reality distinct species of animals, but
that they are free portions of the sarcode of various species
of Spongiadifi.

ORGANIZATION AND PHYSIOLOGY.

Previously to entering on the subject of the organization
and physiology of the Spongiadae in detail, it will be neces-
sary to take a brief view of the general structure of these
animals. Whatever may be their form, or however they
may differ from each other in appearance, there are certain
points in their organization in which they all agree. In
the first place, however variable in its form and mode of
structure, there is always a skeleton present on which the
rest of the organic parts are based and maintained. Amidst
the skeleton, and intimately incorporated with it, are the
interstitial canals, consisting usually of two series ; the first
appropriated to the incurrent streams of the surrounding
water, and the second to the excurrent streams, which they
conduct from the interior of the sponge to the oscula at its
surface, through which they are discharged. In the event
of the absence of the excurrent system of canals, their office
is served by the great cloacal cavities that are found to exist
in some forms of sponges, extending from the base to the
most distant parts of the animal. Beside these large cavi-
ties, there are others of a much more limited character,
the interrnarginal cavities, which are situated immediately
below the dermal membrane, and which receive the water

84 ANATOMY AND PHYSIOLOGY

inhaled by the sponge, and transmit it to the mouths of the
incurrent canals which have their origin in the mtermar-
ginal cavities. Enveloping the entire mass of the sponge
we find the dermal membrane, in which are situated the
pores, for inhalation and imbibition of nutriment, and the
supply of the incurrent canals ; and the oscula, through
which the excrementitious matter and the exhausted streams
of water are poured from the terminations of the excurrent
canals. These parts are indispensably necessary, and are
always present in a living sponge. The attachment of the
Spongiadse to the body to which they adhere during life,
is effected by a basal membrane which presents a simple
adhesive surface, following the sinuosities of the body on
which it is based, entering into holes or cracks and filling
them up, thus securing a firm hold of the mass on which
they are fixed. When it so' happens that the locality con-
sists of sand or mud, their bases frequently assume the
form of branching roots, which penetrate the mud or sand
to a considerable extent ; but they are never instrumental
to the nutrition of the animal — they are simply the anchors
by which it is fixed to its locality for life.

We will now proceed to consider the structure and func-
tions of these organs in the order indicated at the beginning
of this volume, page 4 ; commencing with

THE SKELETON.

There are two important distinctive characters for con-
sideration in treating of the structure of the skeleton :—
1st, the material of which it is constructed; and, 2nd, the
mode of its arrangement.

By selecting the material substance of the skeleton as
the means of dividing the Spongiadas into Orders, we obtain
three well-defined natural groups, which are again readily
divisible into Families, based on the mode of the arrange-
ment of the substance of which the skeleton is com-
posed.

The first Order Calcarea has the primary essential mate-

OF THE SPONGIAD.E. 85

rial composed of calcareous matter, and this division con-
tains but one group :-

Spicula dispersed without order on membranous surfaces,
as in the genus Grant la as denned by Johnston.

The second Order, Silicea, comprises those sponges
in which the primary essential material of the skeleton
consists of siliceous matter. It may be divided into four
sections or groups.

1. Those sponges which have the skeleton composed of
radiating fasciculi of siliceous spicula, as in Tethca Dictyo-
cylindrus, &c.

2. Those in which the skeleton consists of spicula dis-
persed without order on membranous surfaces, as in
Hymeniacidon caruncula, Bowerbank.

3. Sponges having the skeleton consisting of spicula
cemented together into a network by keratode, as in
Halichondria panicea, Johnston.

4. Those sponges which have the skeleton composed of
solid siliceous fibres, as in Dactylocalyas pumicea, Stutchbury.

The third order, Keratosa, consists of those sponges in
which the primary essential material of the skeleton is
keratose fibre, and this may be divided into three sections :

1. Those which have the skeletons constructed of
keratose fibre only, as in the best cup-shaped Turkey
sponges of commerce.

2. Those having skeletons of arenated keratose fibre, as
in the genus Dijsidea.

3. Those which have the skeleton formed of spiculated
keratose fibre, as in Chalina oculata, Bowerbank,
and some of the common West Indian sponges of com-
merce.

In the first group no earthy material of any kind enters
into the structure of the skeleton.

The sponges of the second group, by a natural transition,
pass into the nearly-allied great division of the Halichon-
droid skeletons ; the inability of the former to secrete silex
in an organized form connecting them closely with the
purely keratose, while the instinctive habit of appropriating
extraneous matters recognises the necessity of other material

86 ANATOMY AND PHYSIOLOGY

in the skeleton beside pure keratode ; and the secretion of
it by its own inherent power appears to be the next
natural step in the development of the animals.

In the third division, those having the skeleton formed

* O

of speculated keratose fibre, the gradual development is
also well marked, as in one group we find spicula only in
the primary or radiating fibres of the skeleton, while in
another group they are found in both the primary and
secondary fibres, and are developed simultaneously with the
keratode of the young fibres of the skeleton.

1. Calcarea . a. Spicula dispersed on membranes.

2. Silicea . . a. Spiculo-radiate skeletons.

b. Spicula dispersed on membranes.

c. Spicula cemented together by keratode.

d. Solid siliceous fibre.

3. Keratosa . a. Keratose fibre only.

b. Arenated keratose fibre.

c. Spiculated keratose fibre.

These divisions afford a general view only of the principal
types of the skeleton structure. Other well-defined varia-
tions of these divisions, on which the sub-orders will be
based, will be pointed out and described at length when
we arrive at that portion of our subject in which we shall
treat on the classification of the Spongiada?.

The essential parts of the skeleton of the Spongiada? are
keratode, carbonate of lime, silex, and membrane ; and on
the different modes of the combination and arrangement of
these materials their division into orders, sub-orders, and
genera will depend. It will not be necessary to enter here
into a detailed account of the structure of these respective
parts, as each of them are treated on at length under their
respective heads in the portion of this work devoted to
organography and terminology. I shall therefore confine
my observations to a brief general view of the combinations
of the parts essentially necessary to the construction of the
skeleton.

Keratode, in its application to skeleton structure, has an
exceedingly wide range. In the order Keratosa it is the

OF THE SPONGIADvE. 87

most essential element, and in some genera, as in Spongia,
Spongionella, Verongia, and Auliskia, the skeleton is entirely
composed of it, in the form of anastomosing fibres. In
other genera the keratose fibres are strengthened either by
siliceous spicula or by grains of extraneous matter, selected
and incorporated in their structure by the fibres. In the
order Silicea it performs a much more subordinate part,
appearing only as a cementing material in the formation of
the various combinations of spicula of which the skeletons
of the sponges of this order are principally composed ; but
although in these cases only appearing as a subordinate
element, it is frequently very abundant. In the order
Calcarea it is less in the ascendant than in either of the
other orders, and in many species we are scarcely able to
distinguish it from the membranous tissues of the sponge.
Carbonate of lime, as an element of the skeleton, always
presents itself in the form of spicula of various forms in
combination with membranous structure.

Silica in the skeletons of the order Silicea, presents itself
in a great variety of forms and combinations of spicula.
Sometimes the skeletons assume the shape of a beautiful
regular or irregular reticulation, composed either of a nearly
single series of elongate forms of spicula cemented firmly
together at their apices by keratode, or by numerous
spicula similarly cemented together, forming a strong and
complicated fasciculated thread of reticulations, as in the
Genera Hcdichondria and Isodictya. In other cases, as in
Tethea and Geodia, we find no reticulated structure, but
the spicula are arranged in elongated compound fasciculi,
which radiate from either the base or the central axis of the
sponge, and in Dictyocylindrus we find the reticulate and
the radial system both entering into the structure of the
skeleton, a modification of the former prevailing in the
axis, and the latter existing in the peripheral portion of the
sponge. In Hymeniacidoti neither of these modes of
structure exist, the spicula being simply and irregularly
dispersed over the membranous base of the skeleton ; and
finally we find it simulating the form of pure keratose
fibre, and becoming a rigid and solid siliceo-fibrous skeleton,

B8 ANATOMY AND PHYSIOLOGY

as ill the genus Dactylocalyx. These are but a few of the
numerous varieties of form that exist in the order Silicea,
but as the whole of them will be described in detail in the
course of the characterisation of the genera, it is unneces-
sary to enter further into a description of them at present.

The membranous structures as applied to the composition
of the skeleton assume generally a much less prominent
position than the previously described part, yet in some
few genera they are really the principal element. Thus in
Hymeniacidon they are the primary part of the structure,
and the spicula dispersed over their surfaces are the sub-
sidiary portions only ; and in Microciona Hymerapkia and
Hymedesmia the basal membrane is the indispensably
necessary part of the structure.

SARCODE

Is a pellucid, semi-transparent gelatinoid substance,
variable in colour and insoluble in water. It dries readily,
and its physical characters are restored by immersion in
water with little or no apparent alteration. It is usually
spread thinly and rather evenly over the internal tissues,
but the surface is rarely perfectly smooth ; sometimes it
abounds in obtuse elevations, and occasionally separates
naturally into innumerable irregularly round or oval masses
which are exceedingly variable in size. When examined
by transmitted light with a microscopic power of 400 or
500 linear, it is always found to contain innumerable
minute molecules of apparently extraneous animal or
vegetable matter, the molecules being always more or less
in a shrivelled or collapsed condition, and very variable in
size. Occasionally it is found abundantly furnished with
lenticular nucleated cells, nearly uniform in size, and often
highly coloured. Fig. '285, Plate XVI, represents a portion
of the interstitial membrane of the honeycomb sponge of
commerce, with the sarcode in its natural condition, filled
with the remains of the nutrient molecules in a collapsed
state. Fio-s. 281 and 282, Plate XVI, exhibit the same

OF THE SPONGIAD^E. 89

tissues with the addition of nucleated cells immersed in the
sarcode. In the sponges of commerce it is exceedingly
largely developed, and nothing can be more different in
character than their soft and flexible skeletons and the
animal in its natural condition. Specimens of it in this
state, which have been preserved in spirit immediately on
being taken from the sea, have the whole of their interior
nearly as solid and firm as a piece of animal liver ; the
colour being a very light grey, or nearly white. While the
sponge, as a whole, is sensitive and amenable to disturbing
causes, the sarcode does not appear to be especially so, as I
have frequently observed a minute parasitical annelid which
infests the interior of Spotigilla fuviatilis, passing rapidly
over the sarcodous surfaces, and biting pieces out of its
substance without apparently creating the slightest sensa-
tion to the sarcode, or at all interfering with the general
action of the internal organs of the sponge; and in many
cases we find foraminiferous and other minute creatures
permanently located in its large cavities without appearing
to cause it the slightest inconvenience.

O

When separated from the living sponge, it has at certain
periods an inherent power of locomotion ; small detached
masses of it may be observed slowly but continuously
changing their form, and occasionally progressing in different
directions ; and Carter, in his valuable ' History of the
Freshwater Sponges of Bombay,' describes such detached
masses of sarcode, when progressing and encountering a
fixed point, as dividing longitudinally to avoid the impedi-
ment, and again uniting when it has been passed. This
gliding motion appears to be dependent on an inherent
contractile power, as no cilia appear to have been detected
on the surface of such locomotive masses. Dujardin has
recorded similar movements in portions of the sarcodous
substance from specimens of his genus Halisarca (Hymenia-
cidon Dujardinii,} Bowerbank ; and similar observations
have been recorded by Lieberkuhn and other writers during
their observations of the Spongiadae. I have frequently,
at different seasons of the year, taken portions of the sarcode
from living and healthy specimens of Sponyilla, in which I

90 ANATOMY AND PHYSIOLOGY

could not by the closest observation detect these motions,
which are so readily to be seen at other periods of their
existence ; and even at the same period of the year the
sarcode of some specimens exhibit these motions, while in
others they could not be detected. I have often sought for
these phenomena in portions of the sarcode of llalichondrla
jyanicea, Hymeniaoidon caruncula, and other marine species,
but I have never yet been fortunate enough to detect them.
It is highly probable that the capability of such notions
exists in the sarcode of these and other marine species for a
limited period, but it does not appear that such powers of
motion are a constant condition of this substance.

THE SARCODOUS SYSTEM.

The physical characters and the peculiarities of the
sarcodous matter of Spongilla has engaged the attention of
naturalists of late years to a considerable extent, and its
inherent vitality and mobile powers have long been known
and treated on by many eminent observers ; but its general
functional powers in the marine Spongiadse have scarcely
received that amount of attention that their importance in
the system of the animal demanded. With a view of
assisting in the elucidation of these phenomena, I com-
menced a series of experimental researches on the ' Vitality
of the Spongiadse' in the spring and summer of 1856, at
Tenby, where I had every facility for continually observing
them in a living and healthy state ; and the results of these
observations are published in detail in the reports of the
British Association for the years 1856 and 1857, at the
special request of the Natural History Section. It is
unnecessary, therefore, to repeat these observations here,
and I shall confine myself accordingly to a few general
conclusions arising from the facts developed by previous
observations and by my own experiences as detailed in
these reports. In thus considering the subject, and on
comparing the sarcodous system as it appears in the Spon-
giadse with its structure and functions in other and higher,

OF THE SPONGIAD^E. 91

classes of animals, we must bear in mind that the term
sarcocle is applied in the sense in which it is employed by
Kolliker in his observations on Actinoplirys Sol, and in
accordance with its appearance and functions in the Amoebae,
and not in the more extended sense and general application
of the word as applied to muscular masses of flesh.
Dujardin has also employed the same term in the same
sense many years before Kolliker wrote on these subjects.
As we descend in the organic scale of life, we find the

c> *

great systems of animal functions, the osseous, the muscular,
the nervous, the sanguineous, all becoming simplified, until
at last one or more of them is found entirely wanting.
But the sarcodous digestive system appears never to be
absent. We find it from the highest organized mammals
in the form of the mucous lining of the alimentary organs,
passing through animals of every degree of development,
until the animal itself becomes simplified to the degree of
appearing as a mass of gelatinoid sarcocle only, or with
possibly a central nucleus of membrane, as in Actinoplirys
Sol, &c.

The presence of the stomach has been insisted upon by
some naturalists as the organ absolutely necessary to con-
stitute an animal. On the contrary, it would appear, from
its functions in the higher animals, that it is at best but a
preparatory organ for the less striking but more important
one of the sarcodous system which appears invariably to
cover the digestive surfaces of animals. In mammals it
has hitherto been considered by many physiologists as a
subordinate portion of the digestive system, a merely
lubricating material to assist the passage of the faecal
matters in its course downwards. On the contrary, if we
view it in the light in which it exhibits itself as sarcode,
and not as mere mucous effusion, it becomes the ultimate
and most important part of the digestive system ; the final
receptacle, through its wonderful inherent powers of imbi-
bition of the fully elaborated pabulum presented to it, and
the ultimate refiner and digester of all the nutriment that is
destined to pass into the sanguineous system.

If we examine the digestive surface of the sacular polypi,

92 ANATOMY AND PHYSIOLOGY

of Actinia, or of the common Starfishes, we find this
substance presenting the same unmistakable and peculiar
characters, the pellucid, semi-transparent gelatinoid appear-
ance, abounding in molecnles and minute vesicles always
more or less in a state of collapse. The mucous membranes
of the intestines of a mouse which was drowned in warm
water to preserve the tissues during examination as nearly
as possible in a natural condition, when examined by
transmitted light with a microscopical power of 666 linear,
presented the same characteristic appearances. Some por-
tions of the mucous lining of the intestine abounded more
in the particles than others ; they also varied considerably
in size, and were all more or less in a state of collapse, and
none had the appearance of living and fully distended
vesicles. These molecules were not confined to the surface
of the mucous or sarcodous matter, but were also embedded
at various depths in its substance. They varied consider-
ably in size and character within a small distance. At
one place I observed a group of them, each being of, com-
paratively, a considerable size, while, at a very little
distance, there was but very rarely a large particle to be
observed, and when they appeared to be of more than
average number and size, they were observed to be at the
surface of the mucous or sarcodous structure, as if they
had not yet been absorbed and lessened in size by the pro-
cess of digestion. All these circumstances are indicative of
the molecules being extraneous to the sarcodous structure
itself, and tend to induce us to believe them to be the
nutritive matters in course of preparation for final assimila-
tion with the blood after the previous preparatory portions
of the process of digestion in the stomach.

These are the general characteristics of the sarcodous
system throughout the whole range of the animal kingdom,
and, as may naturally be expected, may be traced in the
Spongiadse, however they may differ in their structure and
organization. Every cavity in the interior of the animal is
coated with a thin stratum of sarcode, over which the incur-
rent and excurrent streams of water, continually passing
through the sponge with a greater or less degree of activity,

OF THE SPONGIADJE. 93

are flowing, bearing with them the molecules of animal or
vegetable matter that are floating in the surrounding water,
and in small specimens of SpongiUa the molecules, thus
imbibed by the pores, may be seen rapidly traversing the
tortuous canals of the sponge, being frequently suddenly
arrested in their course, and adhering to the sarcodous sur-
face over which they are gliding ; and if, while the rapid
inhalent process is going on, and an infinite number of
extraneous particles of matter are seen entering the pores
in every direction, we turn our attention to the excurrent
streams from the oscula, we shall be at once struck with
the comparatively small number of effete particles that
issue from those orifices. While on the contrary, if we
examine the oscula while the gentle breathing inhalation
only is proceeding — and the nutrient particles are rarely
seen entering the pores — we shall not fail to observe that
the amount of effete particles ejected from the oscula is
still continuing with a regularity that is strikingly indi-
cative of their systematic and gradual liberation from the
sarcodous surfaces of the interior of the animal, and it may
be further observed that the molecules thus ejected are
very much below the average size of those previously
imbibed, and that they are always in an exhausted and
collapsed condition.

If sections of a sponge in a living state be examined by
transmitted light with a power of about 500 or 600 linear,
the whole of the sarcodous substance will be seen abound-
ing in the nutrient particles, some simply adhering to the
surface, while others are embedded at different degrees of
depths, exhibiting all the varieties of form and condition
that are so characteristic in the molecules described as
existing in the mucous lining of the intestine of the mouse,
and in many cases, excepting that in the Spongiadas, the
sarcodous surfaces are somewhat more evenly spread over
the membranes on which they repose ; such is their simi-
larity, that the two tissues, so distant from each other in
the scale of created beings, can scarcely be distinguished
from each other under the microscope.

There are other points of similarity existing between the

94 ANATOMY AND PHYSIOLOGY

sarcode lining the interior of the sponge and the so-termed
mucous lining of the intestines of the higher animals.
Under natural circumstances the two substances are in-
soluble in water, but under the effects of certain stimuli
they are each discharged from their natural bases with
great facility ; and where this discharge prevails to any
great extent, it appears to be speedily fatal to the life of
the animal. Thus in cases of extreme diarrhoea in warm-
blooded animals, immediate prostration of the vital powers
is the inevitable result ; the final and most important act
in the sustentation of the vital powers is greatly interfered
with or entirely destroyed, and great prostration of strength
or death is speedily the result. The marine Spongiadaa,
under ordinary circumstances, may be kept in their natural
element, and death may ensue for want of a supply of fresh
water, without any remarkable amount of viscous dis-
charge. But if we remove a living specimen of Halichon-
dria panicea from salt water and plunge it into fresh water,
the result is frequently an immediate and profuse discharge
of a glairy gelatinoid matter. The same result may be
induced by an addition of a considerable quantity of salt to
the sea water in which the animal was contained, or by the
addition of a small portion of alum ; and when once this
viscous discharge has been induced, the life of the sponge is
inevitably destroyed. In others of the lower marine
animals the same effect is induced by similar causes, and
with many of them the immersion in fresh water is noto-
riously the quickest and most certain mode of destroying
vitality, and in these cases the decease is almost always
accompanied by an abundant flow of viscous matter.
Thus if we have this substance upward from ActynopJirys
Sol to man, through the Spongiadse and all its other gra-
dations of animal existence, it is always found to be pre-
sent, and always intimately connected with the digestive
process. Especial organs for respiration, nerves for sensa-
tion, muscles for motion ; all these may apparently be
dispensed with in turn, and yet the animal will perform its
accustomed functions ; but this substance, as mucous lining
of intestine, or sarcode, as I have before observed, appears

OF THE SPONGIAD^:. 95

never to be absent. It even seems to acquire a greater
importance in the animal economy as we descend in the
scale of beings, until the animal in Amceba and Adinoplirys
Sol becomes entirely composed of it ; and in these creatures
it seems to perform all those varied functions which in
other animals are distributed among a numerous set of
especial organs. It thus appears to be the most constant
and perhaps the most important attribute of animal life.
In its most isolated form it apparently supersedes every
other organ in the animal. In Amoeba it appears to exist
in its simplest and most isolated condition, it moves by its
contractile power, and absorbs nutriment. In Adinophrys
it adds another function to its list of capabilities, that of
throwing out pseudo-tentaculse by which it entangles and
conveys its prey to its surface. In the foraminated animals
it develops further powers, it secretes a chambered shell for
the protection of its surface, and throws out pseudo-podia
by which it moves over comparatively a considerable space
in a short period, and anchors itself at its pleasure in any
position or locality it may choose to remain in. As we
proceed higher in the scale of creation its functions become
more limited, but in the act of digestion it always appears
to take a most important part.

The internal vital powers of the Spongiada3 seem to be
resident in this substance, which appears to fulfil in these
animals all the functions of the nervous systems in the
higher classes of creation, gifted with elaborately developed
nervous systems, and if we view this extraordinary sub-
stance in reference to nervous matter, it seems to lead us
irresistibly to the hypothesis that they are to a certain
extent identical, or that the latter enters in a diffused state
into the composition of the former. In plants wre have
movements resulting from irritation closely resembling
those arising in animals from nervous action ; but wrho has
ever seen the nerves in plants ?

In the dermal membrane of sponges we have actions
arising from alarm or injury analogous to those induced by
nervous influence, but no nervous filaments can be detected.
We naturally ask, why does alarm immediately cause the

96 ANATOMY AND PHYSIOLOGY

closing of the pores in Spongitta, and suspend inhalation
and imbibition? What unknown cause is it that effects
these actions usually dependent on the exertion of nervous
energy ? In the opening and closing of the defensive cones
of spicnla in Grantia ciliata we have a resemblance of
muscular action, without the presence of muscles ; but here
we have a sufficient cause for the effect in the active vibra-
tion of the cilia inducing a flow of water which produces
the same results that might otherwise have ensued from
muscular action, but we have no such solution to the
inherent powers of action in the sarcodous membranes of
the Spongiadse, or in sarcode in its purest and most iso-
lated forms. Whence then comes the power that inspires
the action of the cilia in the sponges, if it be not from the
sarcode in which their bases, or the cell whence they ema-
nate, are embedded ? If the cilia be removed from the
animal, enveloped in their surrounding sarcode, their action
is continued vividly for a considerable period, but if a
single cilium be accidentally separated from the mass, its
vibratory motion is almost immediately extinguished ; it
has been separated from the vital influence that endowed it
with action.

But let us return again to the dermal membrane of the
Spongiadae, and its internal lining of sarcode, — what
inherent power then is it that renders this wonderfully
plastic tissue so sensitive and self-acting. Is sarcode
another form of nervous matter? Or is that vital prin-
ciple infused in sarcode ? That it contains an inherent
vitality independent of its connexion with other parts of the
animal, is distinctly proved by its pure existence in Acti-
noplirys Sol, and by its independent action and movements
when portions of it are removed from SponyiUa, or from
some of the marine Spongiadse. If this supposition be
true, then the whole of the phenomena of its existence in
Actinoplinjs Sol, in the Spongiadas and in every other form
is at once explained. Why should we not have nervous
matter without tubular structure surrounding it ? If this
hypothesis, that sarcode is a diffused form of nervous
matter, or that it exists in a diffused form in sarcode, be

OF THE SPONGIAD.E.

true, we have an intelligible solution to an infinite number
of phenomena among the lower classes of animals that
have hitherto been inscrutable. In the higher classes of
animal existence we know well that nervous energy is the
spring whence every other vital power proceeds, and we
trace the nervous system downward in the scale of animal
existences until from a few simple fibres it becomes obso-
lete ; and yet in those creations in which tubular nerves
are no longer to be detected life and action is as vivid in
proportion to their necessities as in the higher classes,
abounding in complicated nervous ramifications. Again,
then, we may ask, whence, in the absence of nerves, comes
the inspiration of all these vital actions, if it be not that
they are due to the inherent nervous properties of sarcode
—a never-failing material in animal existences. Every other
organ may in turn become obsolete, but sarcode never. It
continues its downward course in the chain of existence
until it at last becomes the sole representative of animal life.
If under all these various conditions \ve consider its
modes of action, we shall find that its imbibing powers are
not exerted continually. In the Spongiadce, as in all other
animals, it has its intervals of action and of rest,* and this
habit will perhaps afford us a useful mode of distinguishing
between animals and vegetables. Thus in animals the
imbibition of nutriment is voluntary and at intervals, while
in vegetables it is involuntary and continuous.

THE INTERSTITIAL CANALS AND CAVITIES.

These organs exhibit their most complete mode of de-
velopment in the genus Spongia and in the Halichondroid
sponges, occupying nearly the whole of the masses of the
animals. They consist of two distinct systems, an incurrent
and an excurrent one. The incurrent series have their
origin in the intermarginal cavities immediately within the
dermal membrane, and their large open mouths receive
from these organs the water inhaled through the pores,

* "Report on the Vitality of the Spongiadse," 'Brit. Assoc. Reports ' for
1856, p. 441, &c.

7

98 ANATOMY AND PHYSIOLOGY

and convey it to the inmost depths of the sponge, ramifying
continually like arteries as they proceed in their course
downward, until they terminate in numerous minute
branches. The inhaled fluid is then taken up by the
minute commencements of the excurrent series, which
continually unite as they progress towards the surface of
the sponge, in the manner of veins in the higher animals,
until they terminate in one or more large canals which
discharge their contents through the oscula of the
sponge. This system is found to obtain in the whole
of the genus Spongia and in the massive Halichondroid
sponges, which have their oscula dispersed over their
external surfaces. By this mode of organization the
inhaled fluid, laden with nutritive particles, is poured at
pleasure into the internal cavities of the sponge, flowing
over extensive membranous surfaces coated with sarcode ;
so that the aggregated surfaces become a great system of
intestinal action, fully equal in proportional extent to that
of the intestines of the most elaborately organized mammal.

They do not in every genus exhibit the regularity of
structure described above, and in some cases the canalicular
form resolves itself into a series of irregularly formed spaces.
In other cases, where a common cloaca exists, there appears
to be but one system of interstitial canals, those which
convey the inhaled fluid from the pores through the sub-
stance of the sponge to the parietes of the great central
cloacal cavity which receives the whole of the faecal streams,
rendering the system of excurrent canals unnecessary.

In the Cyathiform sponges we find a somewhat similar
structure. The outer portion of the cup is essentially the
inhalant surface, and the interior of it the exhalant one, and
there accordingly we generally find a great number of small
oscula dispersed on all parts of it, very often having their
margins slightly elevated, that the feecal matter that issues
may be discharged free of the surrounding membrane.

The large fistular projections which form such striking
and beautiful objects in the genus Alcyoncellum are also
great cloacal organs, their dermal membranes abounding in
pores, and their inner surfaces furnished with oscular orifices,

OF THE SPOXGIAD^E, 99

the intervening space being occupied by the interstitial
cavities, the interior forming one large cloaca! cavity,
which discharges its contents through a cribriform mouth
at its distal end. In Grantia both systems, the incurrent
and excurrent interstitial canals, become very nearly obso-
lete, the large intermarginal cavities or cells imbibing the
water through their pores on the distal extremities, and
becoming enlarged and elongated until they reach the
parietes of the great central cloaca, into which they dis-
charge their contents, each through a single osculum, into
a short depression or cavity in the parietes of the great
cloaca, and this shallow cavity represents the nearly obsolete
system of excurrent canals.

The membranes lining the incurrent and excurrent canals
are frequently highly organized. In the common honey-
comb sponge of commerce, when in the same condition as
when taken from the sea, these canals are constructed of a
series of compound membranes, each consisting of simple
interstitial membrane with a layer of primitive fibrous tissue
beneath it ; the fibrous portion consisting of a single series
parallel to each other, and so closely adjoining as to touch
each other through nearly their whole course (Fig. 255,
Plate XII).

When the fibres are clear of the membranous tissue
they appear as simple pellucid threads, but when covered
by the membrane they frequently appear as if moniliform ;
this character seems to be due to minute molecules arranged

O

in linear series on the membrane immediately above them.
These membranes abound in large, open, oval spaces, so that
the tissue assumes very much the appearance of areolar
tissue, as described bv Professor Bowman in his treatise on

7 »/

mucous membrane in the ' Cyclopaedia of Anatomy and
Physiology.''

The layer of membrane forming the surface of the canal
has its fibres disposed at right angles to the axis of the
canal, while those of the layers beneath it assume various
directions, usually in straight lines, excepting in the vicinity
of the areas of communication, around which they curve to
strengthen their margins.

100 ANATOMY AND PHYSIOLOGY

Tn the canals deeply buried in the mass of the sponge
the sides frequently consist of but one layer of membrane
and primitive fibrous tissue, and in this case also the fibres
are always disposed at right angles to the axis of the canal ,
but they are neither so numerous nor so closely packed as
in the sides of the great excurrent canals.

The interstitial membranes are also furnished with these
fibres, sometimes in considerable quantity, but rather irre-
gularly disposed, while in other cases a single fibre only
will be observed meandering across the tissue.

The interstitial membranous tissues in a beautiful little
specimen of Alcyoncellum from the North Sea, for which I
am indebted to my friend Captain Thomas, of the Hydro-
graphical Survey, are very similarly constituted to those of
the sponges of commerce. The membranous walls of the
interstitial cavities are each formed of a series of fibro-
membranous layers, the fibres of each layer being disposed
at angles varying from those above and below it.

Figs. 255, 256, 257, and 258, Plate XII, represent,
portions of the lining membranes of the incurrent and ex-
cnrrent canals, and the mode of the disposition of the
primitive fibrous structure upon them.

INTERMARGINAL CAVITIES.

In the Halichondroid sponges, immediately beneath the
dermal membrane, there are numerous and, comparatively
speaking, large irregularly formed cavities, which receive
the water inhaled by the pores, and convey it to the
mouths of the incurrent canals, which have their origin in
the deepest portions of the spaces. These organs, from
their irregularity in size and form, are not always very
apparent, but if a section be made at right angles to the
surface in a dried specimen of Halichondria panicea or
Ckalina swmlans, Bowerbank, they may be readily detected
and distinguished from the interstitial canals and spaces of
the sponge.

Fig. 800, Plate XIX, represents a section of

OF THE SPONGIAD^E. 101

dria panicea, and Fig. 299, Plate XIX, a similar section of
a branch of Chalina simulans, Bowerbank, showing that,
however varied the forms of the sponge may be, the inter-
stitial cavities are the same in structure and position.

I have never been able, in the Halichondroid sponges, to
detect valvular diaphragms separating these spaces from
the interstitial canals and cavities beneath.

In the genera Geodia and Pachymatisma these organs
assume a very much greater degree of regularity and a
complexity in their organization that are never apparent in
those of the Halichondroid sponges. In Geodia Barretti,
Bowerbank, MS., a highly organized species of the genus,
they are found in the crustular dermis in great abundance.
They are in form very like a bell, the top of which has
been truncated. They are situated in the inner portion of
the dermal crust ; the large end of the cavity being the
distal, and the smaller end the proximal one. The open
month or distal end of the cavity is not immediately
beneath the dermal membrane. There is an intervening
stratum of membranes and sarcode, of about two fifths the
entire thickness of the dermal crust, which is permeated by
numerous minute canals which convey the water inhaled
by the pores to the expanded distal extremity of the cavity.
The proximal end is closed by a stout membranous valvular
diaphragm, which the animal has the power of opening and
closing at its pleasure. It is usually entirely destitute of
the characteristic dermal spicula that are found abundantly
in the adjoining membranous tissues.

The action of the diaphragm of each cavity appears to
be independent of the surrounding ones, the condition or
degree of opening of no two adjacent ones being alike. In
the greater number of cases they were in a closed state,
and in this condition the membrane was filled with con-
centric circles composed of minute rugse or thickened lines,
and at the centre it was closely pressed together, completely
closing the orifice. In some cases the membrane was only
partially closed, and the orifice was either circular or
slightly oval ; in others it was nearly as large as the diameter
of the basal end of the cavity. The pursing of the centre

102 ANATOMY AND PHYSIOLOGY

of the membrane of the diaphragm was always outward as
regards the cavity, so that when viewed from within it
appeared as a slightly funnel-shaped depression, the bottom
of which was conical. The cavities are lined by a smooth
and tolerably strong membrane, abundantly supplied Avith
slender fibrous tissue, disposed in nearly parallel lines at
right angles to the long axis of the cavity.

The adaptation of the skeleton to the support of these
elaborately constructed organs is very remarkable. The
sponge is furnished abundantly with large expando-ternate
spicula, the radii of which are furcated at their apices.
They occur in a series of bundles; the long attenuated
shafts of each fasciculus approximate at their bases, and
diverge thence until the ternate head of each is about
equally distant from its surrounding neighbours, and the
extremities of the rays touch or slightly cross each other,
thus forming a beautiful and regular network, the meshes
being six- or seven-sided, according to circumstances. The
upper surfaces of the radii are firmly attached to or par-
tially imbedded in the under surface of the crustular stratum,
and the areas thus formed are occupied each with the
proximal valvular terminations of one of the intermarginal
cavities.

The progressive development of these inhalant areas,
formed by combinations of the radii of the ternate forms of
spicula in different species of sponges, is very interesting.
In PacJiymatisma they are so indefinite that they can
scarcely be said to exist. The ternate spicula are few in
number, and very irregular in their mode of disposition, and
a faint indication only of their future regular combination to
form the dermal reticulation is apparent. In the more
highly organized genus Geodia we find them in different
species in progressive stages of combination, until, in G.
M'Andrewii and Barretti, the apices of the radii of the ter-
nate spicula are interlaced with each other, and a continu-
ous irregular network is formed, each area of which is filled
with the proximal termination of an intermarginal cavity.
In Dactijlocahjx Prattii, Bowerbank, MS., the structure
advances another stage towards perfection.

OF THE SPONGIAD.E.

There is the same design as that exhibited in the construc-
tion of the dermal areas in Geodia M'Andrewii and Baretti,
but there is a considerable difference in the application of
the areas produced by the combinations of the ternate
apices. In Geodia these areas are placed beneath the highly
organized and regularly formed intermarginal cavities, and
form the framework and support of their valvular proximal
ends ; while in Dactylocalyx Prattii they are situated above
the distal ends of the intermarginal cavities of the sponge,
which have not the regular structure and valvular appendage
of those of Geodia, but are similar to the like organs in the
Halichondroid sponges, and in this position they serve only
to support and strengthen the dermal membrane, which
adheres firmly to their distal surfaces. In this situation
they are subject to a greater chance of pressure and dis-
ruption than in the more deeply seated ones of Geodia, and
accordingly we find extra provisions for the safety of the
junctions of their radii. The shafts of these spicula are
short, stout, and conical, and they penetrate but a very short
distance into the substance of the sponge. They do not
appear to be cemented to any part of the rigid siliceo-fibrous
skeleton, but are merely plunged into a somewhat thick
stratum of membranous structure reposing on the surface of
the skeleton. Their radii are compressed considerably and
extended laterally, so that their planes are in accordance
with that of the dermal membrane, and they present a
greater amount of adhesive surface than those having
cylindrical radii. The ternate rays ramify irregularly.
Sometimes one ram us, after slightly pullulating, remains
nearly obsolete, causing the branch to assume a geniculated
form, like some of the ramifications of a deer's horn, and
no two appear to be exactly alike ; in fact, there is every
appearance that each ray is influenced and modified in its
development by the necessities of combination with the
adjoining spicula, and their apices are directed in such a
manner that they lap over each other in opposing lines, so
that each two form a spliced joint, giving a much greater
amount of strength than the mere crossing of the radii at
various angles, as in those of Geodia. The inhalant areas

104 ANATOMY AND PHYSIOLOGY

thus formed appear to differ very slightly from those of
Halichondr'ta panicea, in each of which several pores are
opened, while those of Dactylocalyx Prattii seem to be
devoted each to a smaller number (Fig. 306, Plate XXIX).

As the ternate spicula thus united for the support of the
dermal membrane would afford it little or no protection
against the voracity of its smaller enemies, we find the ne-
cessary defence in innumerable short, stout, entirely spined,
cylindrical spicula, not exceeding — inch in length ; thus
minute, there is no conceiving a predaceous creature with a
mouth so small that they would not enter and become a
subject of annoyance so great as to interfere seriously with
its attacks on the membrane ; and they are so numerous,
and so closely packed together, that no portion of it equal
in size to the length of a spiculum could be removed
without one or two of them accompanying it.

A still further advance in this system of dermal support
and defence is exhibited in the beautiful harrow tissue of
Dr. A. Farre's siliceo-fibrous sponge, Farrea occa, Bower-
bank, MS., to which his specimen of Euplectclla cucumer,
Owen, is attached. In this case we have a perfect and
regular quadrilateral network of smooth siliceous fibre, from
the angles of which a double set of short, conical, spicular
shafts are projected, each about ~ inch in length and
entirely spined. Each set are at right angles to the plane
of the network, one series pointing inward and serving
the purposes of attachment to the mass of the sponge
beneath, while the other set are directed outward, serving
as defensive weapons ; so that a small piece of this tissue
beneath the microscope closely resembles an agricultural
harrow, with the difference that it has two sets of teeth in
opposite directions instead of one. The dermal membrane
has been nearly all destroyed; but entangled with the
fibres of the skeleton there are some attenuate-stellate
spicula, with which it is probable the dermal membrane was
amply furnished as secondary defences against its minute
enemies.

I believe the surface presented to the eye in the portion
represented by Fig. 811, Plate XXI, to be the external

OF THE SPONGIAD^E. 105

surface, as the fragments of the dermal membrane which
remain all seem to cover that side of the fibres. Generally
speaking, there is some difficulty in detecting the double
series of spicular organs at the angles of the network, but a
reversal of the object beneath the microscope immediately
removes all doubt on that subject.

In Grantia coinpressa and ciliata the intermarginal cavities
appear to attain their highest degree of development, and
are multiplied and expanded to such a degree as to almost
supersede every other organ. The whole sponge in these
species is formed of a great accumulation of elongated cells
or cavities, closely adjoining each other and angular by com-
pression. Their conical distal terminations, abounding in
pores, represent the external surface of the sponge, while
their valvular proximal ends form the inner surface, in con-
junction with the shallow cavities, into the distal ends of
which each cell discharges its contents. These shallow
depressions, intervening between the intermarginal cavities
and the cloaca, are all that remains to represent the incur-
rent portion of the interstitial systems so largely developed
in the Halichondroid sponges, the great cloacal cavity
entirely superseding the excurrent spaces and canals (Figs.
312 and 313, Plate XXI).

In these species of Grantia there is no doubt regarding
the existence of cilia, the whole of these great cavities being
completely lined with them.

It is a question whether the intermarginal cavities share,
in common with the interstitial canals, in the function of
the assimilation of nutriment, or whether they are devoted
solely to the aeration of the fluids of the animal ; and this,
if we consider the structure and extent of the interstitial
canals in the Halichondroid sponges, is probably the case.
In Granlia the abundant provision of cilia in those cavities
at once stamp them as breathing organs ; and although
cilia have never yet been satisfactorily proved to exist in
the intermarginal cavities of the Halichondroid sponges,
there can be no reasonable doubt of their being the hoino-
logues of the large ciliated cavities in Grantia cowpresm
and other similarly constructed sponges. Now, in these

106 ANATOMY AND PHYSIOLOGY

sponges, although the cilia may be readily seen in vivid
action within the open oscula, as I have described at length
in my paper " On the Ciliary Action of the Spongiadae,"
published in the ' Transactions of the Microscopical Society
of London,' vol. iii, p. 137, not the slightest trace of cilia
exists without those organs ; and this seems to indicate that
the aerating functions were strictly confined in these

O t/

sponges to the large intermarginal cavities.

The same mode of reasoning applies equally well to the
intermarginal cavities of Geodia and Pachymatisma, to
which it is probable that the cilia are in like manner con-
fined. The great valves at the proximal ends of these
cavities in this tribe of sponges appear to strongly indicate
a decided separation of the functions of aeration and di-
gestion ; and if this conclusion be true in regard to the in-
ter-marginal cavities of Geodia and Pachymatisma, it will
probably be so in the homologous organs in Grantia ; and
in this case we must look for the digestive surface in the
shallow cavities intervening between the terminal valve of
the intermarginal cavities and the parietes of the great
cloaca, and of the surfaces of that organ itself. The
structure and functions of the intermarginal cavities, and
especially as displayed in Geodia and Pachymatisma, indi-
cates a closer alliance with the great class Zoophyta than
has hitherto been suspected to exist. In the one case we
have an accumulation of individual animals conjoined in
one mass ; in the other, a similar congregation of organs in
place of individuals.

DERMAL MEMBRANE.

The dermal membrane envelopes the sponge entirely.
When denuded of sarcode by partial decomposition, it has
the appearance of a simple, pellucid, unorganized membrane.
In the living state its inner surface is somewhat thickly
coated with sarcode, and it has the appearance of, com-
paratively speaking, a stout, tough skin, and in many
sponges it requires a considerable amount of violence to

OF THE SPONGIAD.E. 107

tear it. The dermal membrane of the Turkey sponge of
commerce, Spongia officinalis, is abundantly supplied with
primitive fibrous tissue. It curves round the margins of
the porous areas, thickening and strengthening the whole
of the dermis to a very considerable extent, but it exists to
a very slight extent in the pellucid membranes of the areas
in which the pores are opened. When alive, it is replete
with powers of life and action of a very remarkable descrip-
tion. Without the slightest appearance of nerves or
muscles, it has the power of opening pores on any part of
its surface, and of closing them again at pleasure, without
leaving a trace of their existence to indicate the spot they
occupied ; and there is no amount of laceration or destruc-
tion that it does not seem capable of repairing or replacing
in a very short period, reproducing itself over extensively
denuded surfaces in a very few hours. It also shares, in
common with the interstitial membranes, the power of
strongly and quickly adhering to other sponges of the same
species with which it may be brought in contact, but never
with those of a different species, however long the two may
remain pressed against each other. In some sponges the
distal extremities of the skeleton pass through and project
beyond the surface of the dermal membrane, while in other
cases the whole of the skeleton is confined within it.

I will not describe at length these remarkable powers of
the dermal membrane, but refer the reader to a series of
observations on the " Vital Powers of the Spongiadae,"
published in the ' Reports of the British Association ' for
1856, p. 438, and for 1857, p. 121, in which I have de-
scribed in detail a series of observations and experiments
on living sponges, which demonstrate in a satisfactory
manner the extent of the vital powers and capabilities of
this highly sensitive membrane.

In some species of sponges the outer surface of the
skeleton is especially modified to strengthen and support
the dermal membrane. Thus, in some of the keratose
sponges of commerce, in parts of the sponge which have
been in contact with other sponges, or with rocks or stones,
we find a fine network of stout fibres immediately beneath

108 ANATOMY AND PHYSIOLOGY

the dermis, as represented by Fig. 310, Plate XX, and
Isodictya varians, Bowerbank, is always furnished with a
fine network of spicula, the reticulations consisting of a
single series of spicula only, and on this framework the
dermal membrane is firmly cemented. Fig. 309, Plate XX,
represents a small portion of this dermal reticulation, mag-
nified 108 linear.

In Halicondria panicea the same description of reticula-
tion prevails, but in this sponge the fibres of the network
are always composed of numerous spicula cemented
together, as represented in Fig. 303, Plate XIX, illustrating
the porous system of the above-named species of sponge.
But this regularity of structure is not constant even in the
same individual ; thus, in Hal. panicea you will often
observe one portion of the dermis beautifully reticulated,
while a closely adjoining spot will be supported by a series
of matted spicula, without any indication of areas for the
pores, and these variations in structure are evidently de-
termined by the presence or absence of those organs at
particular parts of the surface. In other cases, beside a
general attachment of the inner surface of the dermal mem-
brane to the surface of the skeleton, we find it supported
by numerous flat fasciculi of spicula dispersed irregularly on
its inner surface, and differing materially in size and form
from those of the skeleton, as in our common British
species, Hcdichondria incrustans, Johnston. Great variety
exists in these modes of strengthening and supporting the
dermal membrane ; but those which I have described above
will suffice to illustrate the general principles of their appli-
cation. Beside the general systems of external defence, the
dermal membrane is often supplied with special defences.
Thus, in Tetlt.ea muricata, Bowerbank, MS. (Figs. 304 and
305, Plate XIX), we find its outer surface abundantly sup-
plied with elongo-stellate spicula, which project externally
to a considerable extent ; and in Dicfyocylindrus stuposus,
Bowerbank, beside the numerous defensive spicula pro-
jected through the surface, we find the membrane filled
with minute sphero-stellate spicula, which would effectually
protect it from the assaults of any minute enemies that

OF THE SPOTs GIAD.E. 109

might attempt to prey upon it. Fig. 298, Plate XVIII,
represents a small portion of the dermal membrane of this
sponge. This mode of defence is very general in the
genera Geodia, Tethea, and Pachymatisma, and it occasion-
ally occurs in other genera of Spongiadse.

THE PORES.

The pores in the Spongiadse are the orifices or mouths
through which the animals breathe and imbibe their nutri-
ment. They are situated in the dermal membrane, and are
exceedingly numerous when the imbibing powers are in
full operation. In Pachymatisma and Geodia, and in some
other highly organized genera, there is good reason to
believe that they are permanent organs, opening and closing
repeatedly in the same situations. But in the greater part
of the Halichondroid types of sponges they are certainly
not permanent orifices, like the mouths of higher classes of
animals, and in these sponges, when they are in a state of
complete repose, there is not the slightest indication of
their existence. Their usual form is circular, bnt they fre-
quently assume the shape of an elongated oval, and within
a limited range they vary to a considerable extent in their
dimensions ; on the whole, they exhibit a very constant and
universal type of form and size ; however different may be
the internal structure of the sponges, or however great may
be the difference in size of the individuals, they always
appear to maintain their normal characters. No definite
law appears to prevail in their distribution over the surface
of the sponge, and they are liable to appear to a greater or
a less extent on every part of its external surface, wherever
there are intermarginal cavities beneath. The situations
where they may be expected to appear may in many in-
stances be readily recognised. Thus, in Halichondria
panicea, wherever we see on the dermal membrane a well-
defined reticulation of spicula, with clear and distinct areas,
there, when the sponge is inhaling, we may expect to find
the open pores, as represented in Fig. 303, Plate XIX,

110 ANATOMY AND PHYSIOLOGY

while on spots perhaps immediately adjoining where the
dermal membrane is occupied by a thickly interwoven mass,
a felting of spicula, the probability is that not a single pore
can be detected.

In some of the West India fistulose sponges we find the
large or primary area of the dermal surface composed of
keratose fibre, and within these large areas the dermal
membrane is strengthened and supported by a secondary
reticulation of spicula, in the areas of which the pores are
opened. In these secondary reticulations the spicula are
abundant, while in other parts of the sponge the tension
spicula are rather of rare occurrence. In Grantia, a sponge
of a widely different construction to those of the Hali-
chondroid type, they occupy the distal extremities of the
large intermarginal cavities of the sponge, and they appear
to open over the whole of those portions of the cavities not
in contact with the adjoining ones.

In Pachymatisma Joltnstonia, Bowerbank, a British
sponge closely allied to the genus Geodia, we find the
dermal membrane perforated by innumerable pores, some
as minute as -^ inch in diameter, while others attained the
size of —, inch. They are nearly equidistant from each
other, but without any order in their arrangement. Imme-
diately beneath the dermal membrane there is a stratum of
membranous structure and sarcode destitute of ovaries, and
about equal in thickness to one third of that of the whole of
the dermal crust, the remaining two thirds of which consists
of a stratum of ovaries closely packed together, but per-
forated at intervals by the intermarginal cavities. Through
the upper stratum, destitute of ovaries, a small canal
passes from each pore to the nearest adjacent intermarginal
cavity, so that there are a series of them at various angles,
all concentrating their streams of inhaled fluid at the distal
end of the cavity, which is gradually expanded in diameter
to receive them. In these sponges, therefore, each mouth
appears to be furnished with a separate oesophagus, if I
may be allowed the term, connecting it with a stomach-
like cavity, common to a group of mouths above it ; a
system of organization strikingly in unison with that of the

OF THE SPONGIAD.^. Ill

higher classes of animals. In some cases, as in Geodia
M'Andrewii and Barretti, Bowerbank, MS., we find the
pores systematically congregated in groups, as in Fig. 302,
Plate XIX, which represents two groups from the latter
species, and this congregation is accounted for by the
peculiarities of the form and arrangement of the inter-
marginal cavities of that class of sponges.

In my "Further Report on the Vitality of the SpongiadaB,"
published in the 'Reports of the British Association' for 1857,
I have described at length the opening and closing of the
pores in Sponyilla fluviatilis ; each operation is commenced
and terminated in less than a minute ; they are perfectly
dependent on the will of the animal, and in neither case are
they simultaneous, but follow in irregular succession, in
accordance with the necessities of the animal ; and when
once closed, they do not appear to ever open again in pre-
cisely the same spot.

In these wonderful opening and closing operations in the
dermal membrane of Sponyilla, every movement is accom-
plished as systematically and accurately as if there was a
perfect system of nerves and muscles present, while not a
vestige of fibrous structure can be detected in the thin
translucent membrane and its sarcodous lining. No
cicatrix remains for an instant after closing, no indication
of the spot where the opening is the next moment to be
effected.

In sponges exposed to the action of the atmosphere,
between high- and low-water marks, and in dried speci-
mens, the pores can rarely be detected. In the first case
they are carefully closed on the receding of the tide, that
the Avater within them may be safely retained during their
exposure to the atmosphere, and in the latter case the
violence offered to it, and the shock of its removal from its
native locality, is sufficient to induce an immediate closing
of those organs, as I have shown in the details of my
observations on these organs in SpongUla in the volume of
the ' Reports of the British Association' for 1857, to which
I have before alluded. But should a specimen of marine
sponge, after a careful removal from its place of growth, be

112 ANATOMY AND PHYSIOLOGY

placed in a shallow pan of sea-water, and be allowed to die
of inanition, it then frequently expires with the whole or a
considerable portion of the pores open, and in that state it
may be readily preserved for the cabinet.

THE OSCULA.

The oscula are the faecal orifices of the sponge. They
are situated at the distal terminations of the single or con-
centrated excurrent canals of the animal. They vary
considerably in form and size ; sometimes they appear as
single large orifices, while at others they consist of several
small orifices grouped together. When the sponges are
massive and solid, they are usually to be found dispersed
over the dermal surface, but occasionally they are grouped
on the highest portions or on the elevated ridges of the
mass. In Geodia Barretti, Bowerbank, MS., they are
concentrated in deep depressions or pits. In other cases
they are entirely hidden from the view, lining the interior
of elaborately constructed cloacae, situated in the centre of
the sponge, as in Grantia compressa and citiafa, Verongia
Jisti/losa, and a numerous series of species of fistulose
sponges from the West Indies.

They are permanent organs, and are capable of being
opened or closed at the will of the animal, and are subject
to a considerable amount of variation in size and form, in
accordance with the variations in the actions of the sponge.
Thus in littoral sponges they are frequently entirely closed,
and their situation even quite indeterminable during the
period of their exposure to the air ; but when immersed in
water, and the sponge is in the energetic action of the imbi-
bition of nutriment, they are expanded to their full extent ;
but when this action ceases and that of gentle respiration
only exists, many of them close entirely, and others exhibit
apertures not exceeding half their former diameters, while
the imbibition of nutriment was in vivid action. Their
expansion or contraction is not rhythmical ; each can be
opened or closed at the will of the sponge without any

OF THE SPONGIAD.E. 113

apparent effect on the others. Nor is the habit of opening
and closing the oscula the same in every species. Thus in
the course of my observations on Halichondria panicea and
Hymeniacidon caruncula in their natural and undisturbed
localities, I have frequently observed during their exposure
to the air at low tide, that while no oscula in an open
condition could be found in Hymeniacidon caruncula, the
greater portion of those on the specimens of Halichondria
panicea were more or less in an open state.

They appear also to be subject to a considerable amount
of modification as regards situation, even in the same
sponge. Thus in our common British species, Halichondria
pamcea, when of small size, they are situated on the surface
of the sponge, and are scarcely, if at all, elevated above the
dermal surface ; while in large specimens of the same
species we find them collected in the insides of large elongated
tubular projections or common cloacae, and these organs
vary from a few lines only in height and diameter to
tubular projections several inches in height, with an
internal diameter of half or three fourths of an inch. When
they attain such dimensions their parietes are often of con-
siderable thickness, and their external surface becomes an
inhalant one, like that of the body of the sponge.

In many species the oscula are always elevated above
the dermal surface, and these thin pellucid elevations are
permanent, while in others, as in Spongitta fliiviatilis, the
tube exists only during the course of the energetic excur-
rent action ; and in such cases it appears to be subject to
great variation in size and form, as I have shown in the
description of Sponyilla in my " Further Report on the
Vitality of the Spongiadse," ' Reports of the British Asso-
ciation ; for 1857.

INHALATION AND EXHALATION.

The works of the old writers on Natural History are full
of vague opinions on the nature of sponges, but none of
them seem to have seriously studied their anatomy, or to

8

114 \XATOMY AND PHYSIOLOGY

liave kept them alive in sea-water and examined their daily
habits. They appear to have excited abundant attention
in the closet, and but very little in their natural localities.
Their ideas are so loose and incleh'nite that it would really
be a loss of time to seriously examine and attempt to
refute them ; and as Dr. Johnston, in his ' History of
British Sponges/ has given in his Introduction, Chapter II,
an excellent digest of the various opinions of the previous
writers on the subject, I shall content myself with referring
my readers to the work of that eminent author for further
information on these subjects, and of briefly referring to
the few actual observations that appear to have been made
by naturalists.

Marsigli, at the beginning of the eighteenth century, has
stated that he had seen contraction and dilatation in the
oscula of several sponges just removed from the sea.

After Marsigli, Ellis (Ellis and Solander), pp. 184, ISO,
and 187, (see also ' Zool. Journ.,' pp. 375, 370,) enunciated
similar opinions founded on his own observations on the
action of the oscula and their currents ; but neither of those
authors was aware of the true mode of the entrance of the
water into the sponge — a much more difficult problem to
solve than its exit through the oscula.

Cavolini, in his researches, although made on sponges
recently taken from the sea, failed in seeing the action of
the oscula as Ellis had done, and he accordingly disputed
their truth. At a later period, Colonel Montagu, although
actually examining them in the places of their growth,
arrived at similar conclusions to those of Cavolini, and, like
that author, he believed them to be animals of a very torpid
nature. Montagu's reasoning to prove the animality of
sponges is for the most part sound and excellent ; he says :
" Whether motion has ever been discovered or not in any
species of sponge, is not, I conceive, of so much importance
as some naturalists would appear to consider. Those who
are solicitous in their inquiries after the animals which they
have supposed to construct the vesicular fabric of sponges,
have expressed their surprise that in this age of cultivated
science no one should have discovered them, must have

OF THE SPONGIAD^E. 115

taken a very limited view of matter possessing vitality, and
have grounded their hypothesis only upon supposed ana-
logy." He also observes, " The true character of Spongia
is that of a living, gelatinous flesh, supported by innume-
rable cartilaginous or corneous fibres or spicula, most com-
monly ramified or reticulated, and furnished more or less
with external pores or small mouths which absorb the water,
and which is conveyed by an infinity of minute channels or
capillary tubes through every part of the body, and is there
decomposed and the oxygen absorbed as its principal nou-
rishment, similar to the decomposition of air in the pul-
monary organs of what are called perfect animals."
' Wernerian Memoirs,' vol. ii. pp. 74, 75.

Lamouroux's conclusions regarding the nature of sponges
are so thoroughly vague and supposititious as scarcely to
require notice.

Lamarck has placed the Spongiadae in a higher position
than any naturalist who had preceded him, giving them
precedence of the sertularian and celliferous corallines, and
even of the corallidse ; but I cannot concur with him to
the full extent of his conclusions, which, like those of most
previous writers, were derived to a much greater extent
from comparative reasoning than in actual observation of
the animals in a living and natural condition.

Professor Schweigger's opinions are very much more
those of a practical naturalist, and it is evident that he had
closely observed them in a living condition ; but he too
shares the erroneous opinion of his predecessors, that the
oscula were the organs of imbibition, and that no water
entered through the dermal surface. Professor Bell, in the
'Zoological Journal' for June,' 18 24, states that he saw the
action of the streams from the oscula, but, like previous
writers, concluded that they were organs of imbibition as
well as excurrent organs. And it was not until the excel-
lent and accurate " Observations and Experiments on the
Structure and Functions of the Sponge ': were published
in the ' Edinburgh Philosophical Journal,' vols. xiii and xiv,
by Professor Grant, that a correct notion was entertained
by naturalists of the inhalant and exhalant powers of those

11G ANATOMY AND PHYSIOLOGY

bodies. These details by the leamed Professor are so fall
and complete as to leave but little room for the improve-
ment of our knowledge of this portion of their natural
history. And the facts of the imbibition of the surrounding
water by the pores in the dermal membrane, its circulation
through the internal cavities of the sponge, and its final
ejection through the oscula, has been firmly established
and acknowledged by all naturalists who have studied
these animals closely in a living state. Dr. Grant has, in
truth, proved himself to have been, in regard to the aqueous
circulation in the sponge, what Harvey was to that of the
blood of the higher classes of animal life, the first to dis-

o *

cover and to publish the true mode of the circulation of the
water in the animal.

This learned and accurate observer says, " I first placed
a thin layer from the surface of the S. papillaris, in a
watch-glass with sea-water under the microscope, and on
looking at its pores I perceived the floating particles driven
with impetuosity through these openings ; they floated with
a gentle motion to the margin of the pores, rushed through
with a greatly-increased velocity, often striking on the
gelatinous networks, and again relented their course when
they had passed through the openings. The motions were
exactly such as we should expect to be produced by cilia
disposed round the inside of the, pores." — ' Edinburgh New
Philosophical Journal,' vol. ii. p. 127.

The same author, in describing the excurrent action,
says, " The Spongiapanicea (Halichondria incrustans, John-
ston) presents the strongest current which I have yet seen."
Two entire round portions of this sponge were placed
together in a glass of sea-water with their orifices opposite
to each other, at the distance of two inches ; they appeared
to the naked eye like two living batteries, and soon covered
each other with feculent matter.

Stimulated by the recital of the observations of Dr.
Grant, I have often sought these currents flowing; from the

7 o O

oscula, and there is no species in which I have had the
opportunity of examining in a fresh and vigorous condition
in which I have not succeeded in seeing them. In the

OF THE SPONGIAD/E. 117

one observed by Dr. Grant, Halicltondna incrustans, John-
ston, the osctila being few in number and very large, the
excurrent streams are more than usually powerful. In the
course of my investigations " On the Vitality of the
Spongiadas," at Tenby, which are published in the ' Reports
of the British Association' for 1856, and in the "Further
Report," published in the same work for Is57, I have
described a long series of observations of the vital actions
of the Spongiadse as displayed in Hymeniacidon caruncula
and SpongUla fluvial His, in both of which species there was
a perfect accordance in the habits and modes of exertion of
these vital actions.

The power of inhalation appears to be exerted in the
Spongiada3 in perfect accordance with the similar vital
functions in the higher classes of animals, not involuntarily
and continuously as in the vegetable creation, but at inter-
vals, and modified in the degree of its force by the instincts
and necessities of the animal. And it may be readily seen
that the faculty of inhalation is exercised in two distinct
modes ; one exceedingly vigorous, but of comparatively
short duration, the other very gentle and persistent. In
the exertion of the first mode of inhalation, that is during
the feeding period, a vast number of pores are opened, and
if the water be charged with a small portion of finely-
triturated indigo or carmine, the molecules of pigment are
seen at some distance from the dermal membrane, at first
slowly approaching it, and gradually increasing their pace,
until at last they seem to rush hastily into the open pores
in every direction. In the meanwhile the oscula are widely
open, and pouring out with considerable force each its
stream of the excurrent fluid ; and if the reflection of one
of the horizontal portions of a window-frame be brought
immediately over an excurrent stream, it will frequently be
seen that the surface of the water is considerably elevated
by its action, even although the osculum be half or three
fourths of an inch beneath its surface, and this vigorous
action will sometimes be continued for several hours, and
then either gently subside or abruptly terminate. Occa-
sionally a cessation of the action may be observed in some

118 ANATOMY AND 1'HYSIOLOGY

of the oscula, while in others it is proceeding in its full
vigour, and sometimes it will be suddenly renewed for a
brief period in those in which it had apparently ceased.
These vacillations in the performance of its functions is
always indicative of an approaching cessation of its
vigorous action. When the vivid expulsion of the water
has ceased, the aspect of the oscula undergoes a consider-
able change ; some of the smaller ones gradually close
entirely, while in the larger ones their diameters are reduced
to half or one third of what they were while in full action.
Simultaneously with the decline in the force of the excur-
rent action the greater portion of the pores are closed, a
few only dispersed over the surface of the sponge remaining
open to enable the gentle inhalation of the fluid to be
continued, which is necessary for the aeration of the
breathing surfaces of the sponge. The breathing state of
inhalation appears to be very persistent, and I have rarely
failed in detecting it when I have let a drop of water,
charged with molecules of indigo, quietly sink through the
clear fluid immediately above an open osculum. These
alternations of repose and action are not dependent on
mere mechanical causes, and sponges in a state of quiescence
may be readily stimulated to vigorous action by placing
them in fresh cool sea-water, and especially if it be poured
somewhat roughly into the pan, and agitated briskly for a
short period ; and this will take place even in specimens
that have very recently been in powerful action.

No general law seems to guide the animal in the choice
of its periods of action and repose, and no two sponges
appear to coincide entirely in the time or mode of their
actions. In fact each appears to follow the promptings of
its own instinct in the choice of its periods of feeding and
repose.

In the littoral sponges there is a third condition of the
animal, and that is during its exposure to the atmosphere
in the intervals between high and low water, and in some
sponges the pores and oscula are both completely closed.
But this condition does not obtain in all species. Thus,
during the course of my investigations at Tenby, I observed

Ol1 THE SPONGIAD^E. 119

that while amidst the numerous specimens of Hymeniacidou
caruncula and Halichondriapanicea that covered the rocks in
the neighbourhood of St. Catherine's Cave the former rarely
exhibited an open osculuni in the absence of the water,
those of the latter species were frequently more or less
open.

The most beautiful and striking view of the differences
existing between vigorous action and the comparative repose
of the breathing process is exhibited in Grant ia ciliata. In
this species the pores are situated on the obtusely conical
distal terminations of the intermarginal cells or cavities, each
of which is furnished with a long fringe of spicula surround-
ing its porous end (Fig. 34<5, Plate XXVI), their proximal
terminations beini*; cemented, for about a third of their

D J

length, to the slightly curved surface of the base of the cone.
In the state of the comparative repose of aerating inhala-
tion, and when the base of the conical extremity of the
cavity is not distended by the incurrent action, these spicula
all converge to a point at the level of their own apices, and
the water thus gently inhaled passes between the shafts of
the spicula, forming the protective cone to the inhalent pores
and effectually preventing any extraneous matter from
approaching them. But when the vigorous feeding action
commences, the distention of the base of the conical portion
of the cavity brings it into lines parallel to the axis of the
cell, and thus the conical fringe of spicula assumes a cylin-
drical form, and the molecular food of the animal is freely
admitted to the pores.

A corresponding action obtains in the exhalant system
of this interesting sponge. The mouth of the great central
cloaca is furnished with a thick fringe of very long and
slender spicula, which by the contraction of its sides near
the mouth are all brought to assume a conical form like
those appended to the inhalant cavities ; but when the in-
halant action is in vigorous operation, and the oscula are all
pouring their streams into the cloaca, the force of the water
thus accumulated distends the mouth of the cloaca to such
an extent as to cause the fringe of long spicula to assume
the form of an open cylinder, or in some cases it is expanded

120 ANATOMY AND PHYSIOLOGY

to such an extent as to become slightly funnel-shaped, and
in this condition the fecal stream may be seen issuing from
it with considerable force. There are many other interesting
points in the structure of this highly organized and interest-
ing sponge which I will not advert to at length, but refer
my reader to a fuller and more complete history of its
structure published by me in the ' Transactions of the
Microscopical Society of London ' for 1859, vol. 7, p. 79,
Plate V.

Thus we find that inhalation is the primary vital opera-
tion induced by ciliary action, and that exhalation is merely
a mechanical effect arising from the primary cause. We
find also that these actions are separated into two distinct
modes ; the one exceedingly active and vigorous, exerted
only at intervals and for short periods, and the other gentle
and continuous. If we combine the consideration of these
peculiarities of function with those of the anatomical struc-
ture, we find that the incurrent streams are always received
in intermarginal cavities, and that these organs, however
modified, are always present, and in some cases can be dis-
tinctly and strikingly separated from the great mass of the
interstitial canals and cavities of the sponge. If we trace
the course of the inhaled fluids, we find that on their
entrance through the pores they are first brought into con-
tact with the parietes of the intermarginal cavities, and
passed thence into the complicated system of digestive
surfaces which line the incurrent and excurrent canals and
cavities of the sponge, and that the exhausted fluids charged
with fecal matters are finally discharged without the slight-
est return to or intermixture with the contents of the inter-
marginal cavities. We may therefore, it appears to me,
safely conclude that the respiratory and digestive functions
are separated, and that the latter has its seat in the inter-
marginal cavities, and the former in the interstitial canals
and cavities.

The vital energy of the Spongiadse must be very con-
siderable, and the quantity of oxygen consumed by their
respiration great, if we may judge by the effects of their
presence in the vivarium, where their introduction makes

OF THE SPONGIAD^E. 121

sad havoc among the other inhabitants, few being able to
withstand their deleterious presence, and without a large
supply of water and a frequent change of it they them-
selves quickly expire of exhaustion.

NUTRITION.

In treating on the subjects of inhalation and exhalation,
I have described the energetic period of action in the
sponge during the imbibition of the surrounding fluid as
equivalent to the operation of feeding in the higher classes
of animals. And in my " Further Report on the Vitality
of the Spongiadse/' published in the ' Reports of the British
Association' for 1857, p. 121, 1 have described the results of
feeding a small specimen of Sponyillajliiviatilis with finely
comminuted indigo in water, and I have there stated that
" many of the molecules might be readily followed, as they
meandered through the interior of the sponge, and were
seen flowing in every direction. During the maintenance
of this action in full force, when I directed my observation
to the osculum, it was pouring forth a continuous stream
of water, and along with it masses of flocculent matter, and
many of the larger molecules of the indigo that had entered
by the pores ; but it is remarkable that although the finer
molecules of indigo were being imbibed by the pores in
very considerable numbers, very few indeed of them were
ejected from the osculum ; and if the imbibition of the
molecules continue for half an hour or an hour, and then
cease, the sponge is seen to be very strongly tinted with
the blue colour of the indigo, and it remains so for twelve
or eighteen hours, after which period it resumes its
pellucid appearance, the whole of the imbibed molecules
having undergone digestion in the sarcode lining the
interior of the sponge, and the effete matter having been
ejected through the osculum." If we kill the sponge im-
mediately after being thus fed, and examine the interstitial
canals and cavities, we find their sarcodous surfaces thickly
dotted with molecules of indigo.

122 ANATOMY AND PHYSIOLOGY

The faecal matters discharged by the oscula exhibit all
the characteristics of having undergone a complete diges-
tion ; whatever may have been the condition of molecules
of organized matter when they entered the sponge, their
appearance after their ejection is always that of a state of
thorough exhaustion and collapse.

It is difficult to decide with any degree of certainty what
is really the nature of the nutriment of the Spongiadse,
but in the greater number of species it is probably mole-
cules of both animal and vegetable bodies, either living or
derived from decomposition. This appears to be the case
with the greater number of the Halichondroid sponges; but
even among them, as well as other genera, there are pecu-
liarities of structure that are strongly suggestive of car-
nivorous habits. Thus in the first portion of this paper
published in the ' Philosophical Transactions ' for 1858, p.
293, I have described among the interior defensive spicula
a remarkable form, which has been hitherto found in one
sponge only, the spinulo-recurvo-quaternate spiculum,
which " occurs in great profusion in the cavities of the
sponge, clusters of them consisting frequently of as many as
twelve or fifteen radiate from the angles of the reticulations
of the skeleton into the interstitial cavities of the animal."
I have also described, while treating on the internal defensive
spicula, the recurvo-ternate forms, the heads of which are
found projecting their radii, more or less, into the interstitial
cavities beneath the intermarginal ones in Geodia and
Pacliymatisma. The spinulo-recurvo-quaternate spicula,
represented in situ in Fig. 292, Plate XVIII, and the re-
curvo-ternate ones figured in situ in Pig. 354, Plate XXVIII,
e, e, are both admirably adapted to destroy the victims
entangled among them.

I have for a long time entertained the idea that these
elaborate and varied forms of defensive spicula, probably
subserved other purposes than that of the protection of the
digestive surface against the incursions of minute annelids
and other predaceous creatures. They are admirably fitted
to retain and make prey of any such intruders. No small
animal could become entangled in the sinuosities of the

OF THE SPONGIAD^:. 123

interstitial cavaties of sponges thus armed without extreme
injury from the numerous points of these spicula, and every
contortion arising from its struggles to escape from its pain-
ful and dangerous entanglement would contribute to its
destruction, and it may then by its death and decomposition
eventually become as instrumental to the sustentation of
the sponge as if actually swallowed by the animal. How
far this mode of mitrimentation may obtain in the physiology
of these creatures it is impossible, in the present imperfect
state of our knowledge of their habits, to say, but from the
complex, varied, and elaborate structure of these organs, and
from their evident adaptation to retain such intruders,
as well as to defend the internal surfaces from injury, it is
not improbable that their office extends beyond that of the
mere defensive function, and that they are in fact auxiliary
organs for securing nutriment for the use of the sponge. If
this supposition, that the elaborately formed and ingeniously
disposed recurvo-quaternate spicula combine the office of
securing prey with that of defending the interstitial organs
of the sponge, be correct, it may afford a clue to the organic
purpose of the recurvo-ternate spicula with the exceedingly
long and attenuated shafts that so frequently accompany
the stout patento-ternate ones in Geodia Barretti. The
apices of these spicula (Fig. 54, Plate II) rarely attain the
height of the plane of the true connecting spicula, and their
recurved radii are most frequently projected into the large
interstitial spaces immediately beneath the plane of the
proximal ends of the cells of the intermarginal cavities, and
may thus form subsidiary defences to those organs. Although
emanating from the fasciculi of the shafts of the true con-
necting spicula, their form, slender proportion and position
evidently indicate a different office from the spicula with
which they are associated, and no other purpose for them
occurs to me so probable as the one I have suggested above.
Or we may carry the supposition further, and believe them
to be not only defensive but aggressive organs ; also, like
the recurvo-quaternate spicula, their office may be to retain
soft annelids that have intruded themselves through the
oscula into the digestive organs, to aid in the nutrimenta-

124 ANATOMY AND PHYSIOLOGY

tion of the sponge; and this idea appears the more feasible,
as these spicula are never observed in the inter-marginal
cavities, where the decomposition of animal matters would be
offensive to their especial function, but always in the spaces
beneath them, which are the commencements of the diges-
tive system.

The same course of reasoning will apply to their occur-
rence in such considerable quantities amidst the defensive
fasciculi of spicida projected from the surface of Tethea
simillima, Bowerbank, MS., and also of T. crania, the latter
being represented by Fig. 362, c, c, Plate XXXI, in which it
will be seen that the recurvo-ternate heads of the spicula
are always situated beneath the level of the true defensive
spicula. Thus situated they would form an admirable trap
for the entanglement of soft annelids that might attempt to
crawl over the surface of the sponge, and thus they would
be destroyed and retained for the imbibition of their parti-
cles liberated by their gradual decomposition. If this be
not their especial purpose in this situation, I must confess
myself at a loss to imagine their proper function, as the
surface of the sponge is effectually protected by the por-
recto-ternate and large acuate spicula that compose the
defensive fasciculi projecting in such abundance from all
parts of the sponge. If we also consider the structure and
positions of the ordinary forms of internal defensive spicula,
the entirely spined attenuato-acuate ones, in reference to
the idea of their being offensive as well as defensive organs,
we shall not fail to see that, although less striking in their
forms and modes of disposition than the spicula already
described, they are calculated to subserve the office of
retaining prey quite as effectually as the more singular
ones. The abundance in which they occur, the vast
number of spines with which they are covered, the apices
of which are frequently long and recurved, combined with
the mode in which their bases are attached to the fibres of
the skeleton, exhibiting a beautiful combination of strength
and flexibility, are strongly indicative of a purpose beyond
that of mere repulsion.

In the two species of sponges in which are found the

OF THE SPONGIADtf:. 125

acuate entirely and verticillately spined defensive spicula in
situ, represented by Figs. 289, 290, Plate XVII, one
of them has the spicula collected in groups in a manner
very similar to those of the spinulo-recurvo-quaternate
form, and if the latter be considered as organs for the
retention of prey, the physiological purpose of the grouping
together of the former can scarcely be considered in any
other light.

In the isolated positions of these forms of spicula, viewed
in reference to some ideas regarding their physiological pur-
poses, there are circumstances of a very remarkable nature.
These forms of spicula occur in several distinct genera of
sponges, and especially in those having a strong kerato-
fibrous skeleton. Their usual locality is on the fibre of the
skeleton, in which their bases are firmly imbedded, and
from which they are projected at various angles into the
canals and cavities of the sponge, and they are very rarely
seen on the membranes. In Hymeraplda stellifera (Fig.
370, a, Plate XXXIV) and H. clavafa, Bowerbank, both
exceedingly thin coating species, they occur in great quan-
tity, but only on the basal membrane ; a portion of them
being erect, the remainder prostrate. But in another
sponge, a remarkably curious parasitical species, Hymenia-
cidon Cliftoni, Bowerbank, MS. (Fig. 291, Plate XVII),
which having no fibrous skeleton of its own, covers and
appropriates a small fibrous FUCKS, and converts its anasto-
mosing vegetable stalks into an artificial skeleton, closely
coating each stalk of the plant with its membranous struc-
ture, so as to cause them at first sight to be readily mis-
taken for keratose sponge fibre. The whole of the mem-
branous structure of this sponge abounds with attenuato-
cylindrical entirely spined defensive spicula, but they are
all prostrate and intermingled with the skeleton spicula of
the sponge when not in contact with any part of the fibres
of the vegetable, but wherever they are in contact with the
plant they instinctively, as it were, assume the erect posi-
tion, and the false skeleton is bristling with them to as
great an extent as if it were truly a kerato-fibrous struc-
ture. This feature in the habit of the sponge is very

126 ANATOMY AND PHYSIOLOGY

remarkable, and highly suggestive of a capability of adapta-
tion to circumstances that we should scarcely have expected
to find. By the two instinctive habits, — first, that of con-
verting the plant into an artificial skeleton, and then
erecting its spinous spicula on its fibres, — it at once simu-
lates the habits of a kerato-fibrous sponge, and becomes
capable of the carnivorous habits that I have attributed to
those sponges that are so strikingly adapted for preying on
intruding annelids or other such small creatures. In the
species above described, Hymeniaddon C/iftoni, Bowerbank,
MS., the erection of the spicula on the adopted skeleton is
an established habit ; and it may be said to be instinctive
in the species, but I have observed the same fact in sponges
not habitually parasitical. I have a specimen of Micro-
dona carnosa, Bowerbank, a British species, in my posses-
sion in which some small fibres of a tubular zoophyte have
been accidentally included during its growth, and which the
sponge has coated with its own tissues, and from these
adopted columns defensive spicula are projected in a similar
manner to those of the columnar skeleton of the sponge.
In this case we have an instinctive adaptation of an
extraneous substance in a sponge in which the introduction
of foreign substances is the exception, and not, as in other
tribes of sponges, the rule.

In Hyalonema mirabilis, Gray, a sponge nearly related
to the genus Alct/oncellum, we find another extraordinary
series of internal defensive spicula, the structure of which
I have described at length under the head of " Defensive
Organs." These elaborately and wonderfully-formed weapons
are evidently destined for other purposes than that of simple
repulsion. The spiculated cruciform spicula, with their
short stout basal radii planted firmly on the lines of the
skeleton, and projecting from their centre at right angles
to their own plane ; the long spiculated ray furnished with
numerous strong sharp recurved spines, it will be at once
seen, is eminently fitted to retain annelids or other such
prey, and to cause every motion of the struggling victim to
contribute to its own laceration and destruction, while the
structure and mode of attachment of the cruciform base is

OF THE SPONGIADJE.

admirably calculated to resist the force and motions it has
to sustain in such encounters. But these spicula, although
exceedingly numerous, are not the only organs capable of
retaining intruders into the body of the sponge with which
it is furnished, there is in addition numerous large multi-
hamate birotulate spicula dispersed in various positions on
the sides of the interstitial cavities of the sponge, each of
the rotulae consisting of seven or eight stout recurved
flattened radii, which, if immersed in any struggling
animal, would be capable of sustaining a vastly greater
amount of force than many of the spiculated quadriradiate
ones combined, could endure without injury ; and that their
especial office is that of auxiliary retentive organs, is well
demonstrated by the fact that the trenchant edges of the
flattened radii are all at right angles to the line of force
required to tear away their hold of any body in which they
may have been inserted. Thus they appear destined by
nature to secure the prey while its own struggles among
the lacerating organs contributes to its destruction (Fi°-s.
294, 295, Plate XVIII, and Fig. 60, Plate III).

In the modification of the structure of the contort biha-
mate spicula, and their peculiar adaptation to the retention
and destruction of intruders within the sponge, which I
have described when treating on the internal defensive spi-
cula, and which is represented in Fig. 293, Plate XVIII, and
Fig. 112, Plate V, we have precisely the same physiological
principle carried out, but by means widely different from
those I have previously described.

If we consider the whole of these extraordinary organs to
which I have referred in relation to each other, we cannot
fail to see that, however varied their forms may be, there
is every appearance of perfect harmony of design in the
purposes they are destined to effect in the economy of the
Spongiada3.

128 ANATOMY AND PHYSIOLOGY

THE CILIA AND CILIARY ACTION.

Our knowledge of the cilia of the Spongiadae is, compa-
ratively speaking, very small. Dr. Grant is, I believe, the
first author who has seen and described these organs in situ.
This learned and accurate observer, in his paper ' Observa-
tions on the Structure and Functions of the Sponge/ has
described the origin and gradual development of the ova or
gemmules of Spongia panicea (Halichondria incrustans,
Johnston). After the liberation of these bodies from the
sponge, he writes, " The most remarkable appearance exhi-
bited by these ova, is their continuing to swim about by
their own spontaneous motions for two or three days after
their detachment from the parent, when they are placed
separately in vessels of sea-water, at perfect rest. During
their progressive motions they always carry their rounded
broad extremity forward, and when we examine them under
a powerful microscope, we perceive that these motions are
produced by the rapid vibration of cilia, which completely
cover over the anterior two thirds of their surface." And
he further states that they are " longest and exhibit the
most distinct motions on the anterior part," and that they
" are very minute transparent filaments, broadest at their
base, and tapering to invisible points at their free extre-
mities ; they have no perceptible order of succession in
their motions, nor are they synchronous, but strike the
water by constantly and rapidly extending and inflecting
themselves." The author describes the attachment and
spreading out into a thin disk of the ovum or gemmule,
and the cessation of action and gradual disappearance of the
cilia ; and he further observes, " although all visible cilia
have ceased to move, we still perceive a clear space round
the ovum, and a halo of accumulated sediment at a little
distance from the margin." This observation is important,
as tending to prove the existence of ciliary action, although
the organs themselves were too minute to be detected.

Dujardin, in his work on the Infusoria, in Plate III, 19, b,

OF THE SPONGIAD^E.

represents what are apparently the detached cilia and their
basal cells, and which were probably from Grantia compressa.

If portions of a living sponge of this species be torn into
small pieces, and placed in a cell in sea-water under a
power of about 400 linear, groups of the detached cilia and
their basal cells will be readily seen at the margins of the
specimen ; they are usually thus clustered together, and
have a tremulous and indistinct motion. If a small speci-
men of the sponge be slit open and placed in a cell with
fresh sea-water, with the inner surface of the sponge towards
the eye so as to command a distinct view of the oscula, the
cilia will be seen in the area of that organ in rapid motion,
and the extraneous molecules attached to them exhibit the
extent and nature of their oscillations very distinctly (Fig.
313, Plate XXI). If the sponge be carefully torn asunder
in a line at right angles to its long axis, and the torn surface
be placed in a cell with a little fresh sea- water, we occa-
sionally obtain a favorable longitudinal section of some of
the large cells of the sponge, and we then see the cilia in
situ and in motion (Fig. 312, Plate XXI).

The whole length of the cell, from the inner edge of the
diaphragm to its origin near the outer surface of the sponge,
is covered with tessellated nucleated cells, which have each
a long attenuated and very slender cilium at its outer
end. They are oval in form, and have a distinct nucleus.
When in vigorous condition their motions are rapid and
cannot readily be followed, but in some in which the action
was languid, the upper portion of the cilium was thrown
gently backward towards the surface of the sponge, and
then lashed briskly forward towards the osculum, and this
action was steadily and regularly repeated. Their motions
are not synchronous, each evidently acts independently of
the others (Figs. 314, a, b, Plate XXI).

The numbers, situation, and peculiarities of their actions
fully account for the continuous and powerful stream that
issues from the great cloacal aperture of this and other
similarly constructed sponges. The natural rate of the
motions of these organs must not be estimated from the
sections last described, but the estimate must be made

9

130 ANATOMY AND PHYSIOLOGY

from the appearances manifested at the oscular orifices at
the inner surface of the sponge ; a more detailed account
of these investigations is published in the 'Transactions of the
Microscopical Society of London,' vol. iii, p. 137. Fig. 312,
Plate XXI, represents a longitudinal section of the inter-
marginal cavities of Grantia cowpressa with the cilia in
situ. Fig. 313, a view of the small portion of the inner
surface of the sponge, exhibiting the oscular orifices and the
appearance of the cilia in motion within them, and detached
cilia and cells from the same sponge.

In the course of my endeavours to detect the cilia in
Halichondroid sponges, I have frequently observed in slices
of the sponge taken from the surface, that the incurrent
action has continued for a considerable period, while in
sections of the same sponge taken from deep amid the
tissues, no such action of the currents could be detected.
In sections from the surface in which the inhaling process
was in vigorous condition, when the inside of the section
was examined, that peculiar flickering appearance was often
visible in the cavities immediatelv beneath the dermal

t/

membrane, which is so characteristic of minute cilia in
very rapid motion ; and although many molecules were
rushing inward with considerable velocity, others might be
seen which continually waved from side to side but made
no progress forward ; in fact they presented precisely the
appearance that I have described as taking place in the
oscula of the proximal ends of the great intermarginal cells
of Grantia compressa ; and I have no doubt, in my own
mind, that those of the Halichondroid sponges were also
extraneous particles of matter adhering to the apices of the
minute cilia, rendering their motions apparent, while the
cilia themselves were perfectly invisible.

Carter, in his paper on " Zoosperms in Spongilla"
published in the ' Annals and Mag. Nat. Hist.,' vol. xiv,
Second series, p. 334, describes ciliated bodies from a
Spongilla from the water-tanks of Bombay, somewhat
similar to those of Grantia compressa, but the basal cell
appears to be larger and the cilium shorter in their pro-
portions than those of G. compressa. The author, in

OF THE SPONGIADjE. 131

describing the detached cells and cilia, says, " At first the
polymorphism of the cell and movements of the tail are so
rapid, that literally, neither ' head nor tail' can be made out
of the little mass. Presently, however, its power of pro-
gression and motion begins to fail, and if separated from
other fragments it soon becomes stationary, and after a little
polymorphism assumes its natural passive form, which is
that of a spherical cell. During this time the motions of
the tail become more and more languid, and at length
cease altogether." The author continues, " If on the other
hand, there be very large fragments in the immediate
neighbourhood, or an active sponge-cell under polymor-
phism sweeps over the field, it may attach itself to one or
the other of these, when its cell becomes undistinguishable
from the common mass, and the tail floating and undulating
outwards is all that remains visible." This observation is
important, as it accounts in a great measure for our inability
to find the cilia in situ in the living and active condition
of the Spongilla ; and if the structure and imbedment of the
basal cell in the marine sponges be like those in that genus,
the same results would probably arise in the marine species,
rendering it extremely difficult, if not impossible, to detect
these organs in situ and in action.

Lieberkuhn, in his paper in Muller's 'Archiv,' 1856,
pp. 1-19, 319-414, gives an account of the cilia and their
cells in situ. He describes them as forming a single layer
of spherical cells, ~ millim. in diameter, and which, though
touching each other, are not in such contact as to lose their
rounded figure. Lieberkuhn's description of the mode of
disposition of these cells in Spongilla would serve equally
well for those in Grantia compressa. Professor Huxley, in
a paper " On the Anatomy of the Genus TetJtya" published
in the 'Annals and Mag. Nat. Hist.,' vol. vii, p. 370,
describes cells and cilia from an Australian sponge, which
he designates spermatozoa, and which he describes as
having " long pointed, somewhat triangular heads, about
j^th of an inch in diameter, with truncated bases, from
which a very long filiform tail proceeds." These bodies
are figured in Plate XIV, vol. vii, fig. 9.

132 ANATOMY AND PHYSIOLOGY

On a careful consideration of the descriptions of the
ciliated cells seen by the authors I have quoted above, it
strikes me forcibly that the so-called zoosperms and sper-
matozoa of Carter and Huxley are identical in origin and
purpose with the similar organs described by Lieberkuhn,
and those found in situ and in action in Grantia compressa,
and in truth that they are the homologues of the breathing
and feeding organs of the zoophytes and more highly
organized animals.

REPRODUCTION.

The ovaria in sponges exhibit considerable variety in
shape and structure. The most familiar form is that of
Sjjongilla Jluviatilis, represented in Fig. 317, Plate XXII,
in its natural condition.

These bodies have hitherto been usually designated as
genmmles, but this term appears to be inappropriate. Each
of them contains numerous minute vesicular, round or oval
molecules, which are discharged from the foramen in suc-
cession, and each of these appears to be capable of pro-
ducing a sponge. The terms ovarium and ova are there-
fore more in accordance with the rules of modern nomen-
clature, and this alteration in their designation is the more
necessary, as I shall hereafter be enabled to show that in
Tethea lyncurium propagation by true external gemmatian
in that species at least really exists. I propose, therefore,
for the future that all such large vesicular organs containing
numerous molecules or ova capable of reproducing the
species, and of being successively ejected from the sponge,
should be designated ovaria and ova, and that the term
gemmule should be restricted to the isolated bodies which
pullulate from the internal or external surfaces of the parent,
and by ultimate separation become each a distinct indi-
vidual.

The reproductive powers of the Spongiadae have been
treated on to a considerable extent by preceding authors,
and the amount of our information on this subject is, I

OF THE SPONGIAD^l. 133

believe, both extensive and accurate. I will not attempt a
recapitulation of all that has been written on their repro-
duction, but content myself with a slight sketch of our
knowledge of the various modes of propagation that have
been well ascertained and described. From the researches
of the various authors who have written on the structure
and development of Sponyilla and on the marine Spongiadae,
it appears that there are three well-established modes of
propagation: 1st, by ova ; 2nd, by gemmation; and 3rd,
by spontaneous division of the sarcode. The terras ova and
gemmule have been used so indiscriminately by authors,
that it seems to me advisable to endeavour to define and
limit their application in such a manner as to distinctly
separate the one form of reproductive body from the other.
On a careful review of the results of the labours of pre-
vious observers and of my own researches, it appears that
the following may be considered as the varieties that exist
in the modes of the propagation of the Spongiadae : —

1st. By ova without an ovarium.

2nd. By ova generated within ovaria.

3rd. By gemmules secreted within the sponge.

4th. By gemmules produced externally.

5th. By spontaneous division of the sarcode.

On the first mode of propagation by the means of ova
generated in the sponge without the presence of ovaria, very
little seems to be known, and this mode appears to be con-
fined to the true sponges, the genus Sponyia. If we ex-
amine microscopically the fibres of the sponges of commerce
in the condition in which they come into the hands of the
dealers, and before they have been soaked, cleaned, and
prepared for sale, we frequently find the fibres covered with
innumerable minute irregularly ovoid vesicular bodies nearly
uniform in size, dispersed evenly over the surface of the
fibres, and imbedded in a thin stratum of sarcode that coats
the membranous sheath that surrounds them. These
bodies Dr. Johnston believes to be "the matured gemmules
or sporules," and I feel strongly inclined to agree with him
in the conclusion that they are the reproductive bodies of

134 ANATOMY AND PHYSIOLOGY

that tribe of sponges, and no other reproductive bodies
have, I believe, been discovered in the true sponges ; but
in arriving at this conclusion, we must not fail to remember
that our knowledge of these animals in the fleshy and solid
condition in which they are when alive, is so limited and so
few observations have been published regarding them in
that state, that we must not attach too great a value to
these conclusions.

In size and form these ovoid vesicles are very similar to
the ova liberated from the well-characterised ovaria of other
marine species of Spongiadae ; and like them, they present
no appearance of a nucleus. They are somewhat irregular
in their form, and vary to a slight extent in size; an
averaged-sized one measured ^th of an inch in diameter.
Fig. 315, Plate XXII, represents a portion of a fibre from
a Bahama sponge under a power of 400 linear, and
Fig. 316, a part of the same fibre 1250 linear.

Until very recently our knowledge of the vesicular ovaria
of the Spongillidae has been confined to two European
species, but Carter, in his excellent account of the Spongillas
found in the water-tanks of Bombay, has described several
new and interesting varieties of these organs ; and I have
also become acquainted with eight new species from the
River Amazon, through the kindness of Mr. Bate, and of
three un described species from North America, through the
kind and liberal assistance of Dr. Asa Gray, Professor
Leicley and Professor Dawson, of McGill College, Montreal,
Canada. The greater portion of these organs resemble each
other very closely in their natural condition, presenting
generally the appearance of a more or less spherical coriaceous
body, but the structure of their walls, when developed by
treating them carefully with hot nitric acid, is so varied
and strikingly characteristic of their organic and specific
differences, as to render it necessary that I should enter
somewhat minutely into their history. Their structual
peculiarities naturally divide them into two great groups.

1st. Those in which the walls of the ovaria are strength-
ened and supported by birotulate or unirotulate spicula
radiating in lines from the centre to the circumference of

OF THE SPONGIADJ3. 135

the ovarium ; and 2nd, those having the walls of the ovaria
supported by elongate forms of spicula, disposed on or
near its surface at right angles to lines radiating from the
centre to the circumference of the ovarium ; and fortu-
nately the types of these two forms of spicular arrange-
ment on the cortex of the ovarium are admirably illus-
trated in the two European species of Spongilla ; the first
mode existing in Spongilla fluviatilis, and the second
one in S. lacustris. After having described the ovaria
of these two species as types of their respective groups,
I shall in my future descriptions of these organs confine
my observations rather to their anatomical structure
than to their external characters, excepting when the latter
are of an unusual description. These bodies occur in great
profusion in the basal portions of S. JliiviatUis ; they are
spherical and of an average diameter of ~th of an inch, and
they are furnished with a circular foramen at their distal
extremity of about 8i3rd of an inch in diameter. In their
natural condition they exhibit very slight indications of the
birotulate spicula imbedded in their coriaceous-looking
envelope. In the dried state they become cup-shaped by
the contraction of the upper half inward during the process
of desiccation, and in this condition the foramen appears at
the bottom of the cup. The edges of the cup being thick
and round in consequence of the presence of the birotulate
spicula beneath the fold of the membrane, and the surface
becomes pitted with numerous minute lacunae, which are
produced by the adhesion of the inner surface of the
envelope to the distal extremities of the birotulate spicula.
Immersion in water for an hour restores them to their
spherical form, but does not obliterate the lacunae produced
by desiccation ; and I have several times observed that,
under these circumstances, the expansion of the ova within
has forced one or more of them through the foramen.

If we take several of the ovaria, either in the living con-
dition or in the expanded state I have described above, and
place them in a test-tube with a little nitric acid, and raise
the temperature of the whole until the ovaria becomes of a
bright yellow colour and semi-transparent, and then arrest

136 ANATOMY AND PHYSIOLOGY

the operation of the acid by immediately pouring in a
quantity of cold water, we shall have preserved their form
and have retained the spicula in their natural positions, and
have rendered the whole so transparent, as to exhibit their
form and arrangement in the walls of the ovarium, either
in water or mounted in Canada balsam, in a very beautiful
and satisfactory manner. They are packed very closely
together, their shafts being in lines radiating from the centre
of the ovarium to the circumference ; their distal rotulae
supporting the outer surface of its wall, while the proximal
rotulse sustain the inner one. Fig. 319, Plate XXII, re-
presents a portion of one of these prepared ovaria, and
Fig. 319, a, one of the detached spicula. Two views of this
form of spiculum are also represented in Figs. 217, 218,
Plate IX, and a perfect ovarium prepared by acid by
Fig. 318, Plate XXII.

Carter, in his paper " On the Freshwater Sponges in the
Island of Bombay," in describing the birotulate spicula of
the ovaria of Spongilla Meyeni and plumosa, species with
ovaries of very similar structure to those of S. fluviatilis,
states that the spaces between the rotulse are " filled up
with a white siliceous amorphous matter which keeps them
in position." 1 am indebted to the kindness and liberality
of the author for specimens of these species, and I have
frequently subjected their ovaries to the action of hot nitric
acid, but I have never succeeded in finding any intervening
siliceous matter, nor have I ever found any such siliceous
cementing material in any other similarly constructed ovary
of a Spongilla.

In the second group of ovaries of the Spongillidae, re-
presented by those of /Sy. lacustris, in which the walls of the
ovaria are supported by elongate forms of spicula disposed
at right angles to lines radiating from its centre, the ovaria,
in their natural condition, exhibit but very slight traces of
the spicula imbedded in their walls. When dried they cup
inward like those of 8. lacustris ; but the margin of the
cup is thin and sharp compared with that formed in a
similar manner by those of S. Jluviatilis, and they expand
also in like manner when immersed in water. When

OF THE SPONGIAD^E. 137

treated with hot nitric acid they display an abundance of
short, stout, entirely spined subarcuate acerate spicula, one
of which is represented in Fig. 203, Plate IX. These
spicula are in many instances exceedingly numerous ; they
are disposed without order, and overlie each other at
various angles, forming, in their imbed ment in the envelope,
a strong and very efficient irregular network of spicula. A
portion of one of these prepared ovaria is represented in
Fig. 320, Plate XXII.

In the ovaries of the different species of Sponyilla, to be
arranged hereafter in accordance with these structural
peculiarities, there is a considerable amount of general
resemblance, but accompanied with such permanent
variations in the structure of the spicula, and in other
portions of the development of these organs, as to render a
somewhat detailed description of them necessary. Thus
in the development of the birotulate spicula, the ovaries
of Sponyillapltimosa, Carter, exceed any other known species.
The thick walls of these organs are rilled with them in the
state represented by Fig. 208, Plate IX, and the intervals
between their shafts appear to be filled with indurated
sarcode or keratode. In Spot/gilla Meyeni, Carter, the
structure of the walls of the ovaria are strikingly similar to
those of S.Jtiiviatilis, and the form of the spicula the same,
with the exception of the shafts being very much more
spinous, and the size of the spiculum twice that of S.
Jliwiatilis. Fig. 219, Plate IX, represents a spiculum from
an ovary of S. Meycni. The smallest and most simple
development of birotulate spicula exists in Spongilla gregaria,
Bowerbank, from the River Amazon, represented by Figs.
213, 214, 215, and 216, Plate IX.

A gradual transition from the birotulate form to that of
the unirotulate one takes place in the ovaries of S. paulnla
(Fig. 221) and &'. reticulata (Fig. 223), until we obtain the
perfect and beautiful unirotulate form in the ovaries of
8. recuruata, represented by Figs. 224 and 225 in the
Plate quoted above. In all these species there is a general
accordance in the mode of their structure.

The gradual transition from the birotulate to the uniro-

138 ANATOMY AND PHYSIOLOGY

tulate form of spiculimi in the ovaries of Spongilla
reticulata is not the only characteristic difference that
exists between it and its congener. The form and structure
of the ovarium also exhibit marked peculiarities of character,
and it is also furnished with a beautiful reticulated spicular
envelope or case. In its natural condition the ovary fills
the reticulated case, and the coriaceous external surface is
pressed into the areas of the network.

It is usually oviform, but it varies to some extent in
its shape. When treated carefully with hot nitric acid, the
outer coriaceous substance of the ovarium is dissolved,
leaving the inner membrane and the boletiform spicula in
situ; their larger terminations being applied to the distal
surface of the membrane, while their smaller clavate or
stellate ends are projected outward, reaching, in the natural
condition, to very near the external surface of the ovarium.
The foramen is situated at the small or distal end of the
ovary, and differs from that of any other form of the organ
with which I am acquainted, inasmuch as it exhibits a
tubular elongation outward of the lining membrane equal
in length to about its own diameter, causing the ovarium,
when prepared with nitric acid, to appear like an oil-flask
with a very short neck. Fig. 323, Plate XXIII, represents
one of the ovaria prepared with acid, and Fig. 322 one of
the cases in which they are contained.

In Sponyilla Brownii, Bowerbank, there is a still further
deviation in the structure of the spicula of the ovary. The
shaft entirely disappears, and the spiculum is reduced to
the umbonato-scutulate form. They are situated on the
outer surface of the inner membrane of the ovarium, with
the umbones of the scutellse outwards. This mode of dis-
position obviously renders them inefficient for external
defence, and the ovaries have therefore been further defended
by being inclosed within an elaborately constructed case
of reticulated acerate spicula. The ovary is closely em-
braced by this envelope, and small elongate masses of its
outer surface are projected through some of its interstices,
causing it to be more or less tuberculous ; and, from the
smallness of the interstices, the tubercles of the envelope of

OF THE SPONGIAD^E. 139

the ovary are much greater in length than in thickness.
The spicula of the case are disposed in a close and irregular
network, seldom exceeding two spicula in thickness. By a
careful treatment with hot nitric acid, the thick coriaceous
outer portion of the ovariuin may be removed, and its thin
lining membrane, with its stratum of umbonato-scutulate
spicula, becomes an exceedingly beautiful object. The same
mode of operation displays the structure of the reticulated
case of the ovary very much more distinctly than when
viewed in its natural condition. Fig. 321, Plate XXII,
represents two of the cases after treatment with acid, one of
them (d) having the ovary very much reduced in size by the
dissolution of the thick coriaceous portion of its structure.

In the second group of the ovaries of the Spongillidse
there is also a strong general resemblance in structure to
the type-form of S. lacustris, but each species is distinctly
characterised by peculiarities of form and arrangement of
the spicula.

The normal form is spherical, and the walls of the ovaries,
in six out of the seven species with which I am acquainted,
are comparatively thin. In the seventh species, S. Carteri^
Bowerbank (S. friabilis, Carter), they are very thick and
abundantly furnished with cellular structure, arranged in
lines radiating from the centre to the circumference ; each
line consists of nine or ten cells, the length of each being
about equal to the diameter. They are very closely packed
together, and are irregularly angular by compression. Their
combined length varies from about one-fifth to one-sixth
the length of the diameter of the ovariuin. This is the
only species in which I have detected this description of
cellular structure. Fig. 284, Plate XVI, represents a portion
of the surface and a view of the cells in situ.

Although the spiculated coriaceous form of ovariuin pre-
vails so constantly among the freshwater sponges, it is one
of extremely rare occurrence among the marine species ;
and I have met with only one instance of its occurrence, and
that is in a new genus of sponges from Shetland, for which
I am indebted to my late indefatigable friend Mr. Barlee.
The specimen incrusts a portion of the valve of a Pecten,

140 ANATOMY AND PHYSIOLOGY

covering a space about half an inch in length and the eighth
of an inch in breadth, and it does not exceed half a line in
thickness. The ovaries are numerous and closely packed
together, and are distinctly visible to the unassisted eye,
looking like very minute cocoons of some terrestrial insect.
There were nearly thirty in an area equal to about a quarter
of an inch. They are attached by the sides to one or more
branches of the fibrous portion of the skeleton.

The wall of the ovary is very thin, and appears to consist
of a single membrane profusely furnished with acerate
spicula, like those of the skeleton. They cross each other in
every possible direction, and occasionally appear to assume
a somewhat fasciculated arrangement. The ovaries are not
uniform in shape, some being regularly oval, while others
are more or less ovoid. I could not detect any trace of a
foramen in those I subjected to examination. I have
designated this interesting species Diplodemia vesicula in
my description of it. Fig. 324, Plate XXIII, represents
two of the ovaries in their natural condition after immersion
in Canada balsam, magnified 83 linear.

In the genera Geodia and Pacliymcdisma ovaria are pro-
duced in great abundance. They agree in form very closely
with those of Spongilla, but their structure is widely
different, and the soft animal matter that enters so largely
into the structure of those of the freshwater sponges scarcely
makes its appearance in the ovaries of Geodia, their walls
being composed of closely packed spicula, firmly cemented
together by silex. Their situation in the animal is also differ-
ent from those of Spongilla, in which they are dispersed amid
the interstitial tissues, but principally towards the base of the
sponge, while in Geodia and Pacliymaiisma they are con-
gregated in large quantities immediately beneath the dermal
membrane ; and when they have shed their ova they per-
manently retain their situation, forming a thick crustular
dermis for the protection of the softer portions beneath :
a few only are found dispersed in the interstitial membranes
of the sponge. The progressive development of this kind
of ovarium is very nearly the same in every species of Geodia
or Pachymatisma in which I have had an opportunity of

OF THE SPONGIAD.E. 141

examining them. In an early stage they appear as a
globular body of fusiformi-acerate spicula, radiating regu-
larly from a central point in the mass. As the individual
spicula increase in diameter there is a corresponding disten-
sion of the ovarium, and as the spicula do not lengthen
in proportion to their increase of diameter a central cavity
is produced, in which the incipient ova very shortly appear.
The spicula of the wall of the ovary continue to increase
considerably in diameter, but very little in length, and their
distal terminations become gradually less acute as they
approach the period of the full development of the ovary.
When this organ has attained its greatest diameter, their
distal extremities cease to lengthen, and a gradual change
in the form of the spicula is effected, their apices extending
in diameter and assuming a truncated form, and the whole
of them becoming firmly cemented together, so as to form
a common flat smooth surface to the siliceous skeleton of
the ovarium, each spiculum having now changed from the
acerate to the acuate form, their proximal acute terminations
forming the common inner surface of the cavity of the
ovarium, which is now filled with an opaque mass of ova.
A single conical orifice or foramen has also been produced
in a portion of the wall, through which the ova are destined
to be ejected. The proximal end of this foramen is very
much the smaller of the two, so that, as soon as an ovum
has fairly entered this conical tube, there is no longer any
impediment to its ejection : and the manner in which this
is effected is very interesting, and appears to be as follows.
When the ova have attained maturity, the proximal termi-
nations of the spicula which have not been cemented
together like their distal ones, are progressively and simul-
taneously lengthened, thereby encroaching on and gradually
lessening the diameter of the cavity within, so that the ova
are compressed and forced through the foramen ; and this
process appears to be continued until the whole of them
have been ejected, and the cavity becomes completely filled
by the continued encroachment of the proximal ends of the
spicula of the walls of the ovarium.
L In Fig. 327, Plate XXIII, two ovaries from Geodia

142 ANATOMY AND PHYSIOLOGY

McAndrewii containing ova are represented : (a) contains
abont the greatest quantity of ova that is found within
these organs. In this one the distal terminations of the

O

spicula of the skeleton are still somewhat rounded, and
slightly elevated above the common surface ; while in (b\
which has been partially exhausted of the ova, the spicula
have their distal terminations flat and somewhat angular,
and they are level with the general surface, thus indicating
a greater age and a fuller development than obtain in the
one represented by (a], and not a less amount of secretion
of ova, as might possibly be imagined. These circum-
stances are strongly indicative of the fact that the ovaria,
both in an active and effete state, are permanently seated
in the sponge, and that the ova only are discharged from
it. So in like manner the existence of the ovarium in
SpongiUa retictilata and Brow?iii, Bowerbank, confined
within a strong spicula case firmly incorporated with the
skeleton, is strong presumptive evidence of their also being
permanent organs, and not of the nature of gemmules which
separate from the body of the sponge when they arrive at
maturity and are ejected through the great faecal orifice.

Many other species of Geodia with which T am acquainted
afford these ovaria in great abundance, and with some vari-
ations in size and form from those in G. McAndrewii,
Bowerbank, MS., but in no other sponge are they so large
and so completely developed.

Fig. 325, Plate XXIII, represents an adult ovarinm from
Geodia McAndrewii with the conical foramen on its summit,
and the distal ends of the skeleton spicula flat and angular.
.Fig. 326 represents a small portion of the surface of the
same specimen as seen with a linear power of 308, ex-
hibiting the flatness and angularity of their distal apices.
Pig. 329, Plate XXIV, represents a portion of a young
ovarium having the distal ends of the skeleton spicula
disunited and acutely conical. Fig. 328, Plate XXIII,
represents a portion of a section of an ovarium of G.
McAndrewii, exhibiting the radial arrangement of its
component spicula.

In Pachymatisma Jolimtoma, Bowerbank, a British

OF THE SPONGIADJE. 143

species common on the rocks in the neighbourhood of
Torquay, and which I described in a paper read before the
Microscopical Society of London in 1841, these organs
assume an oval form ; they are also considerably depressed.
In a young specimen of this species of sponge in my pos-
session, the progressive development of the ovaria is very
strikingly illustrated. Fig. 330, Plate XXIV, represents
an adult ovarium. Fig. 331, one in a semideveloped state,
and Fig. 332, one of the same organs in a very early stage
of development. In another species of sponge from the
South Seas we find a singular variety of this class of
ovarium. It is oval in form, the length being to the breadth
as five to three, but it is so much depressed as to appear
rather like a dermal spicular plate than an ovarium ; but the
radiate arrangement of its component spicula is perfectly
visible with a power of 666 linear, and their distal termi-
nations as separate and distinct as those of Geodia or
Pachymatisma. The situation of the foramen is also well
defined in many of them. Fig. 333, Plate XXIV, represents
a mature ovarium ; Fig. 334, a fragment of one to exhibit
its degree of thickness; and Fig. 335 represents one of the
same species of ovarium in an early stage of development.
I have seen four species of sponge which have this descrip-
tion of ovarium ; in one it is very considerably longer in
its proportions than that represented by Fig. 333, Plate
XXIV, and in another species it is somewhat shorter.

Since the preceding portion of the account of the ovaria
was written I have received a very remarkable specimen of
these organs, which differs materially in its structure from
any of the forms that I have previously described. The
sponge consists of a small portion of basal membrane, closely
resembling that of a Halichondraceous species. It was
found by my friend Mr. J. Yate Johnson coating rocks
and stones at Madeira. The remains of several exhausted
ovaria are dispersed over the surface of the membrane, a
few only retaining their original form and proportions.
They do not appear to have had a spicular skeleton, but to
have consisted of a coriaceous envelope strengthened and
supported by a reticulated skeleton of apparently keratose

144 ANATOMY AND PHYSIOLOGY

structure. They are nearly globular, and are firmly
cemented to the membrane by a broad basal attachment.
Although themselves apparently in an effete state, the
membrane on which they are seated was in a decidedly
living and active condition. It is thickly coated with
sarcode, and abundantly furnished with equi-anchorate
spicula. Numerous slender acuate or subspinulate spicula
are also dispersed over its surface, which are occasionally
fasciculated after the manner of the first indications of the
formation of a Halichondraceous skeleton. But the most
interesting feature of the membrane is, that at intervals
over the whole of its surface, and especially at those parts
most free from the dispersed spicula, there are small de-
tached groups of spicula, each consisting of two or three
irregular fasciculi crossing each other at various angles, re-
sembling in every respect the early stages of development
of the gemmules or ova so graphically described by Dr.
Grant in his account of the gemmules of the sponge he has
designated HaJichondria pamcea.* The presence of these
early developments of the ova is precisely in accordance
with the discharged and effete condition of the ovaries, and
is just such an effect as might naturally be expected under
such circumstances. Fig. 336, Plate XXIV, represents
one of these ovaria seen by a microscopic power of 108
linear ; Fig. 337, a small piece of the reticulated wall of
the ovarium with a power of 308 linear ; and Fig. 338 re-
presents the development of one of the ova and the sur-
rounding equi-anchorate spicula with a power of 108
linear.

GEMMULES.

If we adopt as a definition that a gernmule is a body not
containing ova, but that it is a vital mass separated from
the parent and capable of being ultimately developed into
a single individual possessing the same specific characters

* ' Edinburgh New Philosophical Journal,' vol. i, p. 163 plate ii, figs. 24
—29.

OF THE SPONGIAD^E. 145

and capabilities as the parent mass, we must consider the
reproductive bodies so ably and minutely described by
Dr. Grant in his paper " Observations on the Structure and
Functions of the Sponge/'* not under the designation of
ova, but rather under that of gemmules ; and indeed the
learned author seems to have entertained some doubt of
their being correctly designated by the former term, as in
speaking of them in a subsequent portion of his paper in
page 14, he says, " since these germs or so-named ova are,
&c. ;" I have therefore been induced to arrange them under
the designation of Gemmules.

Dr. Grant describes their first appearance in the sponge
in the months of October and November " as opaque yellow
spots visible to the naked eye, and without any definite
form, size, or distribution, excepting that they are most
abundant in the deeper parts of the sponge and are seldom
observable at the surface ;" he also states that " they have no
cell or capsule, and appear to enlarge by the mere juxta-
position of the monad-like bodies around them. As they
enlarge in size they become oval-shaped, and at length in
their mature state they acquire a regular ovate form."
When they have attained a fully-developed condition, they
separate from their attachment to the parent and pass out
of the faecal orifices. At this period of their existence the
learned author states that they are endowed with sponta-
neous motion, in consequence of their larger extremity being-
furnished abundantly with cilia, which the author describes
as " very minute transparent filaments, broadest at their
base, and tapering to invisible points at their free extremi-
ties." After floating freely about for a period, they attach
themselves to some fixed body, adhering firmly to it, and
spreading themselves out into " a thin transparent convex
circular film." The author further states that " when two
ova in the course of their spreading on the surface of a
watch-glass come into contact with each other, their clear
homogeneous margins unite without the least interruption,
they thicken, and produce spicula: in a few days we can

* 'Edinburgh New Philosophical Journal,' vol. i, p. 16, plate ii, figs. 24-29.

10

146 ANATOMY AND PHYSIOLOGY

detect no line of distinction between them, and they con-
tinue to grow as one ovum."

I have never had the good fortune to see the living
gemmule with its cilia in action, as described by Dr. Grant;
but I have frequently found Halichondraceous sponges with
an abundance of these gemmules attached to their tissues ;
and I have in my possession a beautiful little specimen,
dredged off Shetland, for which I am indebted to my kind
friend Mr. Bailee, which is very illustrative of Dr. Grant's
description of the mode of the development of the young-
sponge after the ovum or gemmule has attached itself. On
a fragment of a bivalve shell there are more than twenty or
thirty of Dr. Grant's ova or gemmules, which are all in the
same early stage of development, each forming a small
group of extremely slender spicula. The groups are sepa-
rate from each other, but very closely adjoining. The
diameter of one of the largest does not exceed ^th of an
inch, and their distance from each other is about half or
once the diameter of one of them. In their present state,
as represented by six of them in Fig. 339, Plate XXIV, it
is evident that they are separate developments ; and it is
equally evident that a slightly further amount of extension
would have caused them to merge in one comparatively
large flat surface of sponge. We see by this instance that
a sponge is not always developed from a single ovum or
gemmule, but, on the contrary, that many ova or gemmules
are often concerned in the production of one large indivi-
dual ; and this fact may probably account for the compara-
tively very few small sponges that are to be found,— a few
days probably serving by this mode of simultaneous deve-
lopment to form the basal membrane of the sponge, of con-
siderable magnitude, as compared with the individual ovum
or gemmule, or with a sponge developed from a single
ovum only. This mode of reproduction appears to have
a very wide range. It is common to several distinct genera
of Halichondraceous sponges ; and I have observed it also
in a siliceo-fibrous sponge, Ipldieon panicea of the Museum
of the Jardin des Plantes, Paris. Pig. 340, Plate XXV,
represents a small piece from the interior of the skeleton of

OF THE SPONGIADJS. 147

Ipliiteon panicea. Although the latter sponge is so widely
different in structure from the Ilalichondraceous tribes of
sponges, its mode of propagation by gemmation seems to
be in perfect accordance with them. In Tethea cranium
the same mode of reproduction by gemmnles obtains, but
the form of the organ is different, and there are other pecu-
liarities in its growth and development that are extremely
interesting.

The form of the gemmules is regularly lenticular ; and
there are two distinct sorts of them, which are always
grouped together. The first is rather the smaller of the
two, and has a nucleus of slender curved fusiformi-acerate
spicula only. The bases of the spicula cross each other at
the centre of the gemmule, and the apices radiate in all
directions towards the external surface, but do not, in the
fully developed state of the gemmule, project beyond it.
The second sort of gemmule is furnished with three distinct
forms of spiculum. The first are like those of the genmmlo
described above, slender fusiformi-acerate ; the second arc
attenuato-porrecto-ternate, the radii being given off from
the apex at about an angle of 45 degrees ; and the third
form is attenuato-bihamate or uniharnate, and the hooked
apices of this form arc projected further than either of the
other two forms, but do not pass beyond the inner surface
of the tough dermal envelope of the gemmule when in the
adult state. I have examined a great number of these
gemmules, and could never find in the form first described
any indication of either tern ate or hamate spicula, and I am
therefore satisfied that they are separate descriptions of
gemmule, and that the first form is not a transition state
from the young and undeveloped to the fully developed
one. In like manner I have closely observed the second
form, and have always found it uniform in character, and
furnished with the whole three forms of spicula that charac-
terise it. It is highly probable that this marked difference
in structure is sexual, and, from the more highly developed
condition of the second or large form, that it is the female
or prolific gemmule ; but on this point we must at present
be satisfied with conjecture only, as although I have searched

148 ANATOMY AND PHYSIOLOGY

diligently for spermatozoa in both forms of gemmule and
in the surrounding sarcode, I have not been able to detect
anything resembling them. But that such bodies do occur
in some species of Tcthca appears to be the case, Professor
Huxley having described and figured bodies which he
believed to be spermatozoa in a paper published in the
'Annals and Mag. Nat. Hist.' Second Series, vol. vii, p 370,
plate 14, as occurring in a species of Tetltea found in one
of the small bays in Sydney Harbour, Australia. The
gemmules represented by Pig. 343, Plate XXV, consists of
(a) one of the larger and supposed prolific gemmules, and (b]
one of the presumed male gemmules in situ, X 108 linear.
Wherever the former occurs, the latter appear always to
accompany them in the proportion of about two or three to
one. They are not seated like the ovaria of Geodia at the
surface of the sponge, but are always found on the inter-
stitial membranes at a considerable depth within the
sponge. The immersion of the specimen in Canada balsam
has rendered the marginal lines of the gemmules undis-
tinguishable from the surrounding sarcode, but their
natural boundaries would be just beyond the extreme
points of the spicula.

Fig. 344, Plate XXV, represents one of the larger gem-
mules in its natural condition and separated from the
sponge, by direct light and a linear power of ^0.

The reproductive bodies in the Tethca, described by
Professor Huxley, do not resemble those in T. cranium ;
no spicula are either described or figured as existing in
them, and in these respects they appear much more to
resemble the reproductive organs described by Dr. Grant
as existing in the Halichondraceous sponges of the Firth of
Forth. But I am not surprised at this discrepancy, as in
Tetlica simillima, Bowerbank, MS., in the collection of the
Royal College of Surgeons, from the Antarctic regions of
the South Sea, a species very closely resembling T. cranium,
the gemmules are so like those of the latter species as not
to be readily distinguished from them in their natural con-
dition ; but when microscopically examined, not the slight-
est trace could be found of the smaller, and what I con-

OF THE SPONGIADJ3. 149

ceived to be the male gemmule in T. cranium. 1 have
several other species of Tctkea in my possession, but 1 have
not yet found geni mules in the interior of any of them.

EXTERNAL GEMMULATION.

In Tethea ly natrium we have gemmnles produced ex-
ternally, which are perhaps much more entitled to that de-
signation than any of the reproductive organs previously
described. The fasciculi near the base of the Tethea are
protruded considerably beyond the surface of the animal,
and at the termination of each there appears a small mass
of sarcode, which assumes a more or less globular form. If
their bodies be immersed in Canada balsam and examined
microscopically, they will be found to contain not only the
spicula projected from the parent, but a second series,
which have been secreted in the mass which have assumed
the mode of disposition so characteristic of the skeleton of
the parent Tethea. I am indebted to my late friend Mr.
T. H. Stewart for this interesting fact, and for the speci-
mens illustrating it. They were found in Plymouth
Sound.

Fig. 342, Plate XXV, represents one of these gemmules
with a portion of the skeleton fasciculus on which it is pro-
duced, under a linear power of 50.

PROPAGATION BY SARCODOUS DIVISION.

The fact of the resolution of the sarcode of the interstitial
tissues of Spongilla into small masses of unequal size and
variable form has long been known to naturalists, and that
when separated from the parent body each becomes capable
of locomotion, and of ultimately becoming developed into a
perfect sponge. Carter, in his valuable paper published in
the ' Journal of the Bombay branch of the Royal Asiatic
Society,' No. 12, 1849, has given a minute account of their
structure and motions when separated from the species
which form the subjects of his paper, and his descriptions
are in perfect accordance with the similar bodies separated

150 ANATOMY AND PHYSIOLOGY

from our European species S.Jluviatilis, which I have had
frequent opportunities of observing, and of confirming the
history given by him of their locomotive powers and con-
tinual inherent motions. The author designates these
bodies " sponge- cells," and treats of them as if they had a
well-defined cell-wall, while their eccentric changes of form
are perfectly inconsistent with such a structure. Lieberkulm,
in treating of these bodies under the name of motile spores,
states that he has never succeeded in discerning a " cell-
membrane ' around these particles, and my own observa-
tions are in perfect accordance with his experiences. The
truth appears simply to be that any minute mass of sarcode,
whether separated voluntarily or involuntarily, has inherent
life and locomotive power, and is capable of ultimately de-
veloping into a perfect sponge ; and in the course of this
process the dermal membrane is produced at a very early
period, and this, surrounding an agglomeration of minute
masses of sarcode, may have been mistaken by Carter for a
cell membrane. The same author, in his observations
' On the Species, Structure, and Animality of the Fresh-
water Sponges in the Tanks of Bombay,' states " that when
the transparent spherical capsules which contain the granules
within the seed-like bodies are liberated by breaking open
the latter under water in a watch-glass, their first act is to
burst ; this takes place after the first thirty-six hours, and
their granules, which will presently be seen to be the true
ova of a proteaniform infusorium, varying in diameter from
about the ^th part of an inch to a mere point, gradually
and uniformly become spread over the surface of the watch-
glass. On the second or third day (for this varies) each
granule will be observed to be provided with an extensible
pseudo-pediform base ; and the day after most of the largest
may be seen slowly progressing by its aid, or gliding over
the surface of the watch-glass in a globular form by means
of some other locomotive organs."

This description is strikingly similar to the same author's
account of the masses of sarcode separated from the sarco-
clous lining of the interstitial canals of fyjoiiyilla ; but it
must be observed that, in the development of the egg, the

OF THE SPONGIADJE. 151

tirst act is to liberate itself from the membranous envelope ;
and the contents thus hatched become moving masses of
free sarcode, but without the locomotive cilia that are found
on the so-called ova or gemnmles of the marine sponges, so
minutely and accurately described by Dr. Grant in his
papers " On the Structure and Functions of the Sponge " in
the 'Edinburgh New Philosophical Journal,' vol. ii, p. 129.
This author describes the ova or gemmules of HaUchondria
panicea {Hal. incrustaiis, Johnston), after having floated
freely about for a period by means of the cilia around its
larger extremity, as attaching itself to a fixed body by its
smaller end and then gradually settling down in the form of
a broad flat mass, and after losing its cilia being gradually
developed in the form of the parent sponge. Thus every
description by these close and accurate observers tend to
the conclusion that the multiplication of the sponge is
effected by the origination in the ovum, or by the agglome-
ration in the form of gemmules, of particles of sarcode.
The action of the minute masses of sarcode liberated by the
bursting of the envelope of the ovum, and their subsequent
development, is precisely that of the so-called sponge-cell
liberated from the mass of the sarcode lining the interstices
of the sponge, and of the gemmules described by Grant
when sessile ; each moves independently at first ; each unites
with its congeners into one body : and the results, both in
means and end, are precisely the same, but their origin is
different. The one is a generation of sarcode within a
proper membrane in the form of an egg, while the others
are the production of a gemmule by independent growth,
or by spontaneous division of the sarcodous substance of
the sponge.

Both these modes of propagation occur in the same
species, Spongillajluviatilis, but I have never yet seen them
both well developed in the same individual. Where the
ovaria were abundant, the sarcode appeared even and con-
sistent in its structure, and, on the contrary, if it exhibited
manifest symptoms of granulating, very few or none of the
ovaria could be detected. This double means of propaga-
tion is by no means uncommon among the Zoophytes.

152 ANATOMY AND PHYSIOLOGY

I have never seen the spontaneous granulation of the
sarcocle in any living marine species of sponge ; but as the
vital powers and general physiological characters of that
substance appear to be the same in all the Spongiadae, how-
ever varied in form and structure, it is highly probable that
perpetuation by spontaneous or accidental separation of
minute masses of sarcode is by no means confined to
Spongilhi ; and from the concurrent testimony of all who
have investigated the subject, that every molecule of sarcode,
however minute, has inherent vitality, and the power of
uniting with its own congeners whenever they may chance
to come in contact.

GROWTH AND DEVELOPMENT OF SPONGES.

The growth of the sponge does not appear to be con-
tinuous, but periodical, as we may observe in the branching
species, and especially in Isodlctya palmata, Bowerbank.
If the sponge be held up between the eye and a lighted
candle, as many as five or six of the former pointed termi-
nations of the sponge in succession, from near the base to
the apex, may be seen ; and the former lateral boundaries
are also equally distinct, the oscula being most frequently,
but not always, continued through the new coating of the
lateral development of the spongeous structure. New
branches are also frequently thrown out during the last
period of development at various parts of the stem, where
no indication of branches existed previously. In all these
newly-developed parts, it may be observed that the primary
lines of the structure of the skeleton, or those radiating at
nearly right angles to the axis of the sponge, are those
which are first developed ; and at the extreme points of the
branches they are frequently seen projecting for, compara-
tively, a considerable distance in the form of single unsup-
ported threads or filaments ; but as we trace these lines
inward, we find the secondary, or connecting fibres increas-
ing in number, and the network becoming closer and more
fully developed. The same mode of development may be

OF THE SPONGIAD^E. 153

traced in Chalina ocidata, but not to such an extent as in
Isodictya palmata. In the sessile massive species of Hali-
chondroid sponges the same mode of development seems to
obtain, as I have frequently traced the different stages of
growth in sections at right angles to the surface of the
sponge.

ON THE CLASSIFICATION OF THE SPONGIAM.

WHILE the arrangement of other subjects of natural
science has occupied the attention of some of the most
laborious and talented naturalists of every age, the Spong-
iada3 appear to have scarcely attracted sufficient attention to
have excited any writer on natural history to a serious
attempt at a systematic classification. This neglect has not
arisen from any incapacity for a definite arrangement on the
part of the Spongiadse, as the organic differential characters
of the numerous groups into which, by careful examination,
they may be readily divided are as varied and as widely
removed from each other as are the strikingly distinct and
well defined divisions of the Corallida3, and the number of
species I believe to be very much greater than those of the
latter class. Of British species alone I am already ac-
quainted with more than 150, and new ones are continually
being discovered by the aid of the dredge. It becomes
therefore a matter of necessity that we should classify their
permanent varieties of structure, and found on them a series
of orders, suborders and genera, and through these sub-
divisions become enabled to recognise more readily the very
numerous species of these animals which abound in all parts
of the world.

De Blainville proposed to include the whole of the
Spongiadne under the designation of Amorphozoa ; but this
term is objectionable, as all sponges cannot be considered
as shapeless, on the contrary many genera and species
exhibit much constancy in their form. Neither can the
term be justly applied to their internal structure, as we find

154 ANATOMY AND PHYSIOLOGY

in Grantia, Geodia, Tethea, and other genera, regular and
systematical structures which are very far removed from
shapelessness. I have therefore thought it advisable to
adopt Dr. Grant's designation of Porifera, a term which
embraces the whole of the Spongiadee, and which is truly
descriptive of the most essential general action of the
animal's power and mode of imbibing nutriment, which in
every species with which I am acquainted is, by a series of
minute pores, distributed over the external membrane of
the sponge.

Besides this universally existent character there are others
which are strikingly characteristic of the class, although not
so universally prevalent as the porous one. Thus the
skeletons of the SpongiadcG are always internal, but in the
material and mode of construction they vary to a very con-
siderable extent. Sponges may therefore be defined as
fixed, aquatic, polymorphous animals ; inhaling and imbib-
ing the surrounding element through numerous contrac-
tile pores situated on the external surface ; conveying it
through internal canals or cavities, and ejecting it through
appropriate orifices ; having an internal flexible or inflexible
skeleton, composed of either carbonate of lime, silex, or
keratode ; with or without either of these earthy materials.
Calcareous skeletons always spicular. Siliceous skeletons
either spicular or composed of solid, laminated, and con-
tinuous siliceous fibre.

Propagation by ova, gemmulation, or spontaneous division
of its component parts.

Dr. Grant, in his learned and elaborate ' Tabular View
of the primary divisions of the Animal Kingdom/ published
in ]8G1, has divided the Porifera into three orders, based
on principles which I have adopted. The first order is
Keratosa, in which the skeletons are essentially keratose
and fibrous ; the second, Leuconida, is composed of the
calcareous sponges ; and the third, C//ali.>iida, consisting of
the siliceous sponges. I have not adopted the full and
precise definition of each of these Orders as given by the
learned Professor, as, if the whole of the distinctive cha-
racters in the first and third of them were insisted on in

OF THE SPONGIAD^E. 155

the determination of the orders to which many exotic
.species belong, it would lead in numerous cases to inex-
tricable confusion. The term Leuconida is also objection-
able, as all calcareous sponges are not white, and colour is
at best but a very uncertain character even in the determi-
nation of a species ; I have therefore adopted the principles
of the arrangement of Professor Grant, with the following
modifications of position and descriptions of the charac-
teristics of each order.

1. CALCAREA. Sponges the skeletons of which have as
an earthy base carbonate of lime.

2. SILICEA. Sponges in which the earthy base consists
of siliceous matter.

3. KERATOSA. Sponges in which the essential base of
the skeleton consists of keratose fibrous matter.

While thus assuming the principles of arrangement
enunciated by the learned Professor, I have been induced
to vary the mode of the disposition of his Orders from the
following considerations.

In the highest vertebrated animal types we invariably
hind the skeleton principally composed of phosphate of
lime with a small portion of carbonate of lime and other
substances, the whole consolidated by cartilage. As we
descend the scale of the Vertebrata we find the salts of
lime decrease in proportional quantity until they occur in
minute detached patches only, and cartilage becomes the
essential base of the skeleton.

In the great tribe of Mollusca we find carbonate of lime
prevailing in their shells to the exclusion of phosphate of
lime, and in the compound Tunicata we have a structure
analogous to that of the cartilaginous tribe of Fishes. In
the massive subcartilaginous body of this tribe there is no
continuous or connected earthy deposits. This material of
the skeleton exists only in the form of detached masses of
radiating spicula. As we descend in the animal scale we
find carbonate of lime entirely absent, and silex replacing
it in the elaborate and beautifully constructed loricas of the
marine and freshwater infusoria.

If we are to reason from these gradations of structure

156 ANATOMY AND PHYSIOLOGY

and apply our reasoning to the SpongiadaB, we should then
give precedence to the calcareous sponges as representing
in the class the highest order of secretive power ; and if
we add to these considerations the regularity of structure
and function and the full development of ciliary action that
exists in Grantia ciliata and compressa and the allied
species, I think it scarcely allows of a doubt that this order
should take precedence of the others in an arrangement of
the Spongiadae.

The siliceous sponges naturally follow in succession, and
the Keratosse, from their imperfect secretive powers and
their low order of organization in other respects, would

.

indicate their position to be thd last in the series.

ON THE GENERIC CHARACTERS OF THE SPONGIADAE.

The foundation of the genera of the Spongiadse has
hitherto been based principally upon form and other
external characters of an equally unstable description, and
in many instances genera have been named without the
slightest attempt to characterise them. As a generic
character form is inadmissible, inasmuch as each variety of
it is found to prevail indiscriminately in genera differing
structurally to the greatest possible extent.

I will not enter on the history of the genera that have
been proposed by previous writers on the Spongiadse, as
the greater portion of those which have been published will
hereafter be found to have been adopted, with certain
revisions of their characters, in the series of genera I pro-
pose to establish, but I shall beg to refer such of my readers
as may be desirous of further information on that subject
to page 70 of Dr. Johnston's admirable introduction to his
' History of British Sponges and Lithophytes.'

Having thus rejected form and other external characters
as the foundation of generic descriptions, we naturally
resort to the anatomical peculiarities of the animal for these
purposes ; and here fortunately we rind a variety in struc-
ture and form, and a constant adherence to their respective
types that admirably adapt them to our purpose.

Or THE SrONGTAD^E. 157

If any portion of the animal remains, whereby we may
recognise it as one of the Spongiada3, it is always the skele-
ton, and it is therefore advantageous to adopt this most
persistent portion of the animal as the foundation of our
generic descriptions. But this is not the sole reason for
such a conclusion, as it is not only the most enduring por-
tion of the animal, but it is also the most undeviatingly

n ^

regular in the form and arrangement of its component
structures. However great may be the variations that
exist in size and form between different species of the same
genus, or between individuals of the same species, the cha-
racteristic tissues of their skeletons are always found to
harmonise in their structural peculiarities. It appears,
therefore, advisable in these animals, as well as in the
higher classes, to select the skeleton as the primary source
of generic distinctions. Other portions of the permanent
organs may be occasionally resorted to when necessary as
auxiliary characters, such as the incurrent and excurrent
canals, the intermarginal cavities, the cloaca, and the
various modes of reproduction. Each of these characters
are of use in generic descriptions to a certain extent, but
none of them are absolutely necessary to the determination
of a genus, and occasionally we find one or more of these
modes of organization entirely absent ; we may therefore
consider them not as primary, but rather as secondary or
auxiliary generic characters.

I therefore propose to consider the varieties in the con-
struction of the skeleton as the foundation or primary
source of divisions into genera, and to dedicate that portion
of the animal especially to that purpose ; the auxiliary or
secondary characters being resorted to only when required
to aid and assist the primary ones ; and it is only to a very
limited extent that they are in reality available. Thus the
cloaca in the Order Calcarea becomes a very important
means of generic distinction, and in some cases in the
Order Keratosa it is also a prominent character, while in
Silicea it is generally absent. In some species of this
order, as in Alci/oncella/m, Pofymastia, and JIali/p/i,t/scina, it
assumes a normal character, while in several species of

158 ANATOMY AND PHYSIOLOGY

Halichonclria. and in H. panicca, it assumes very striking-
proportions in excessively developed specimens, whilst in
others it is either an occasional, uncertain, and progressive
organ, or is altogether absent.

The mode of propagation is also an uncertain character.
Thus in Tethea cranium we find it to IDC by internal gem-
mulation ; in T. lyncurium by external gemmules ; and in
other species of the genus no gemmules of any description
have hitherto been detected. In Gcocfia, Pacliymatisma,
and Spowgilla the general structure and mode of disposition
of the ovaria render them valuable auxiliary generic cha-
racters, but in other cases they are of little or no value.

The intermarginal cavities are available as generic cha-
racters in Gcodia and the nearly allied species, and in the
same sponge the relative position of the connecting spicula
form good distinctive characters in the genera Geodia,
Ecioncw/a, and also some of the siliceo-fibrous sponges.
In Alcyoncelliim, Polymastia, and Geodia the position and
appendages of the oscula are also available, but generally
speaking those organs are so mutable as to render them of
little value as generic characters.

The following tabular view of the arrangement I propose
to adopt, will perhaps render the details regarding the dis-
tinctive characters and natural affinities of the genera more
read ily com prchensible ,

OF THE SPONGIAD/E.

159

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Genera.

Grantia, Fleming.
Leucosolenia, Bowerbank.
Leuconia, Grant.
Leucogypsia, Bowerbank.

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Spongia, Linnaeus.
Spongionella, Bowerbank.
Halispongia, Blainville.
Chalina, Grant.
Verongia, Bowerbank.
Auliskia, Bowerbank.
Stematumenia, &c., Bowet
Dysidea, Johnston.

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160 ANATOMY AND PHYSIOLOGY

Order I. CALCAREA.

The number of species of calcareous sponges that are
known are comparatively so few, and the four genera into
which I have divided them are naturally so well charac-
terised as to render the establishment of suborders unne-
cessary. Hereafter, when we are acquainted with a greater
number of species and other varieties of organization
become known, the genera now established may become
the types of suborders, for which office their distinctly
different modes of construction render them eminently
efficient.

Although the calcareous structure of the species of this
order appear to entitle it to precedence in the arrangement
of the Spongiadae, it does not maintain in the structure of
its skeleton throughout the whole of the genera the same
high type of formation that is exhibited in Grantia coiti-
pressa, Johnston, and the allied species, and we observe a
progressive decline in regularity of structure in its genera
very analogous to what we find existing among the Hali-
chondroid tribe of sponges ; but in this respect they only
follow the same laws of gradual degradation that obtain in
every other class of created beings, and this gradual decline
in regularity of structure should not therefore militate
against the claim of even the lowest in organization of the
tribe from taking precedence of the siliceous sponges.

Dr. Grant was the first naturalist who decided that the
spicula of a certain group of small sponges were composed
of carbonate of lime, and he separated them accordingly
from those the spicula of which were siliceous, and assigned
to them the generic name of Leucalia (' Edinburgh Ency-
clopaedia,' vol. xviii, p. 844) ; and subsequently, in his
' Outlines of Comparative Anatomy/ he changed that
name to Leucouia. In 1828 Dr. Fleming gave to the
group the name of Grantia, in compliment to the learned
naturalist who had first pointed out their peculiar
structure.

OF THE SPONGIAD^E. 161

A careful examination of the British species of this
Order will very soon satisfy a naturalist that there are at
least four distinct forms in the organization of the skeleton,
and that each is fully entitled to generic distinction. Thus
in Grantia ciliata and couipressa, Johnston, we find the
sponge to be constructed of a series of cells, each having
separate parietes, and extending from the dermal surface to
near the inner surface of the sponge, where they discharge
the feecal streams into a common cloacal cavity. In
Grantia botryoides, Johnston, the system of cells is entirely
wanting ; the sponge is composed of a single thin stratum
of membranous structure and spicula, surrounding a large
cylindrical cloacal cavity, from the terminations of which
the faecal streams are discharged. In Grantia nivea, John-
ston, we find the sponge massive and irregular in form,
containing numerous capacious cloacal cavities, each termi-
nated by a single large mouth, the interstitial structures
between the sides of these great cavities and the dermal
surfaces of the sponge consisting of irregularly disposed
membranes and spicula, permeated by contorted interstitial
cavities, terminating in simple orifices or oscula in the sides
of the great faecal cavity into which they discharge their
excurrent streams; and in Leucogypsia Gossei, Bowerbank,
the sponge is massive, without cloaca, formed of irregularly
disposed membranous tissues and spicula, and with oscula
at the external surface, thus simulating to a great extent
the mode of structure of the Halichondroid tribes of
sponges.

The sponges of this Order appear to possess a high
degree of vital power, and I have rarely failed in finding
the excurrent orifices in vigorous action in either Grantia
comjjressa, ciliata, or botryoides when recently taken from
the sea. In G. compressa, especially, I have often observed
the inhalant and exhalant actions remarkably vigorous ;
and if a drop of water containing finely comminuted indigo
be mixed with the water in which they are immersed, they
will become deeply tinctured with it in a very few seconds.
This vigorous action is accounted for by the highly deve-
loped ciliary system, which may be readily seen in action

11

162 ANATOMY AND PHYSIOLOGY

if the sponge be carefully split open and immersed in fresh
cold sea-water, and examined with a power of about five
or six hundred linear by transmitted light. The cilia will
be seen in rapid action just within the oscula which termi-
nate each of the large angular interstitial cells of the
sponge. This action, and the mode of the disposition of
the cilia within the cells, I have described at length in the
' Transactions of the Microscopical Society of London/ vol.
iii, p. 137, pi. xix. In accordance with these variations
in structure I purpose dividing the British species into four
genera.

CLASS— P 0 R I F E R A, Grant,
ORDER I.— CALCAREA.

Genera. GRANTIA.

LEUCOSOLENIA.

LEUCONIA.

LEUCOGYPSIA.

GRANTIA, Fleming.

Sponge. Furnished with a central cloaca, parietes con-
structed of interstitial cells, more or less regular and
angular in form, disposed at right angles to the exter-
nal surface, and extending in length from the outer to
very near the inner surface of the sponge, where each
terminates in a single osculum.

Type, Grantia conipressa, Johnston.

The cloaca varies in its form and proportion. In some
species it has invariably one large terminal mouth, while in
others it is furnished with several mouths from which the
excurrent fsecal streams are discharged.

The interstitial structures of the sponges of this genus

OF THE SPONGIA1XE. 163

assumes a greater amount of regularity than is found to
exist in any other genera of these animals. The whole of the
parietes of the sponge are formed of somewhat angular
cells, the sides of which belong to the individual cell, and
are not common to each other. The lengths of the cells
in proportion to their diameters vary in different species,
and also in the same species in proportion to the age and
thickness of the parietes of the sponge. The cell-walls are
formed of comparatively stout transparent membrane,
strengthened and supported by numerous triradiate spi-
cula, and the whole length of the cell from the inner edge
of the osculum to near the outer surface of the sponge is
closely studded with tesselated nucleated cells, each of
which is furnished with a long attenuated cilium. Each
interstitial cell terminates in a single osculum, slightly
within the plane of the inner surface of the sponge. I do
not remember to have ever seen these oscula entirely
closed. When the inhalant action of the sponge is in
vigorous operation, the excurrent streams may be seen
issuing from them with considerable force, and the cilia
appear in action immediately within them.

Hitherto the mouths of the great cloacal cavity of the
sponges of this tribe have been described as Oscula ; but
if we carefully examine the structure of these and similarly
formed sponges, we shall find in all cases that those organs
exist only on the inner surface of the great cloacal cavities.

The construction of the interstitial cells is best demon-
strated in a longitudinal section of a dried specimen of
Grcmtia ciliata, mounted in Canada balsam, and in a
specimen so prepared spaces are seen between the cells
which are often nearly half the size of the cells. These
spaces are most probably produced by the contraction of
the tissues induced by the mode of the preparation of the
object, and do not exist in the living sponge, but they
serve admirably to demonstrate the fact that each inter-
stitial cell has its own special parietes, and that the
divisions between the cells are not common to each other.
Pigs. 31:2, 313, Plate XXJ, and figs. 345, 346, a,
Plate XXVI.

164 ANATOMY ATVD PHYSIOLOGY

LEUCOSOLENIA, Boiverbank.

GRANTIA, Fleming and Johnston.

Sponge. Fistular. Formed of a single layer of triradiate
and other spicula, surrounding a large central cloaca,
which extends into all parts of the sponge.

Type, Grantia botryoides, Fleming.

The structure of Grantia botryoides, Fleming, differs
essentially from that of Grant /a compressa of that author,
inasmuch as there is a total absence of the interstitial
cells which are so characteristic of the latter sponge ; and
its structure is equally discrepant when compared with
that of Grantia nivea of Fleming ; for although it possesses
cloacae in common with that species, it has no approxima-
tion whatever to the massive Halichondroicl form of the
substance of that sponge. On the contrary, its parietes
consist of a single thin layer of spicula and membranous
tissues surrounding a large central sinuous cloaca. Figs.
347, 348, Plate XXVI.

LEUCONIA, Grant.

GRANTIA, Fleming and Johnston.

Sponge. Furnished with cloacae, one or more. Parietes
of sponge formed of a mass of irregularly disposed
interstitial membranes, and triradiate and other spi-
cula ; permeated by sinuous excurrent canals, the
oscula of which are irregularly disposed over the
surfaces of the cloacae.

Type, Grantia nivea, Fleming.

Grantia nivea of Dr. Fleming is very different in its
structure from either G. compressa or ciliata, or of G.
botryoides of that author. It has not the regular inter-

OF THE SPONGIAD^E. 165

stitial structure of either of the first two, nor the simple
fistulose form of the latter one ; but with the exception of
the form of the spicula, it closely simulates the structural
character of the siliceous genus Halichondria, while it is
allied with the before-named calcareous sponges by the
possession of cloacae. In consequence of these marked
differences in the structure of the skeleton, I have separated
it from Grantia as defined by Dr. Fleming, and constituted
it a genus, adopting the term Leuconia, which was pro-
posed by Dr. Grant as a general designation of the whole
tribe of calcareous sponges. Figs. 351, 352, Plate
XXVII.

LEUCOGYPSIA, Bowerbank.

Sponge. Massive, without cloacae ; formed of irregularly
disposed membranous tissues and spicula. Oscula at
the external surface.

Type, Leucoyypsia Gossci, Bowerbank.

The sponges of this genus are still further removed in
structural character from the higher organized genera of
calcareous sponges Grantia and Leucosolcnia than the genus
Lcucoma is. In the arrangement of the interstitial mem-
branes, and the mode of dispersion on them of the skeleton
spicula, there is a manifest similitude to the structural
peculiarities of the genus Hymeniacidon among the Silicese,
and we find a corresponding simplicity in the characters of
the spicula in Lcucoyypsia, the type of this genus. There
are no regularly determined cloaca? projected from the
surface as in Lcuconia, and the excurrent canals of the
sponge merge in each other, until they unite in one large
canal immediately beneath the osculum, in the manner
generally prevailing in the great mass of Ilalichondroid
sponges. These large canals have defensive spicula similar
in structure to those of the other genera of calcareous
sponges. The only known British species of this genus is
L. Gossei, Bowerbank ; but I am acquainted with an exotic

166 ANATOMY AND PHYSIOLOGY

species, L. algoaensis, Bowerbank, MS., which is not un-
common on specimens of Zoophytes and Fuci from Algoa
Bay and its neighbourhood. Figs. 349, 350, PL
XXVI.

ORDER II.— SILICEA.

The genus Halicliondria> as established by Fleming and
adopted by Dr. Johnston, when applied to the arrange-
ment of exotic as well as British species, embraces so wide
a range as to afford but little assistance in the determination
of species. Under this designation every known sponge
would be arranged having silex as the earthy basis of its
skeleton, however varied their anatomical structure might
be, excepting the few species contained in the genera
Geodia, Tethea, and SpongiUa.

Dr. Johnston, in his ' History of British Sponges/
has divided the British species into three sections, de-
pendent on their form, a character so mutable among the
Spongiadse, as to render it of little value under any cir-
cumstances, when unaccompanied by structural peculiari-
ties. I have therefore thought it advisable to distribute the
genera included in the order Silicea among seven suborders,
founded on the most striking peculiarities of the structure of
the skeleton.

The first of these will consist of sponges having spiculo-
radiate skeletons. Skeletons not reticulated, but composed
of spicula radiating in fasciculi or separately from the base
or axis of the sponge. This order will contain as many as
fourteen distinct genera, the whole of which have skeletons
the spicula of which are arranged in radial order. The
mode of the radiation in these fourteen genera is not pre-
cisely the same, but they form three closely according
groups, of which the leading genus of each of the first two
may be considered as the type.

OF THE SPONGIAD^E. 167

1. Geodia, Lamarck. 4. Alcyoncettum, Quoy et

2. Pachymatisma, Bower- Gaimard.

bank. 5. Polt/mastia, Bowerbank.

3. Ecionemia, Bowerbank. G. Halyphysema, Bowerb.

7. Ciocali/pta, Bowerbank.
The second group contains :

1. Tetltea, Lamarck. 3. Dictyocylindrus^QW&fo.

2. ffalicnemia, Bowerb. 4. Phakettia, Bowerbank.

In the whole of the first two groups, excepting Halypky-
sema, the skeleton radiations are fasciculated to a greater or
less amount in the different genera.

The third group will comprise :

1. Microciona, Bowerbank.

2. Hymeraphia, Bowerbank.

3. Hymedesmia, Bowerbank.

The most striking general character in these three genera
is the extremely thin coating form of the sponge, and the
radiation of the skeleton spicula, either singly or in an ir-
regularly fasciculated form, from a common basal membrane,
the thickness of the sponge in some of the species being
less than the length of one of the radiating skeleton spicula.

Suborder I. Spiculo-radiate skeletons. Not reticulate.
Composed of spicula radiating in fasciculi or sepa-
rately from the base or axis of the sponge.

GEODIA, Lamarck.

Skeleton. Spicula fasciculated, radiating from the base or
central axis of the sponge to the surface. Dennis
crustular, furnished abundantly with closely packed
ovaria. Ovaria siliceous, composed of cuneiform
spicula, firmly cemented together by silex, in lines
radiating from the centre of the ovary. Pores fur-
nished with cesophageal tubes, terminating in the
distal extremity of the intermarginal cavities. Inter-

168 ANATOMY AND PHYSIOLOGY

marginal cavities separate, symmetrical, subcylindri-
cal ; each furnished with a membranous valve at its
proximal extremity.

Type, Geodia gibberosa, Lamarck.

The genus, as described by Lamarck,* is so loosely
characterised that I have thought it better to reconstruct it
entirely than to endeavour to amend it. I have therefore
given a new series of characters, founded solely on its
structural and organic peculiarities. I am acquainted with
seven species, all of which perfectly agree in the essential
generic characters as thus constructed.

The type specimen of Lamarck's Geodia gibberosa in the
Museum of the Jardin des Plantes of Paris, the organiza-
tion of which, through the kindness of Professors Milne-
Edwards and Valenciennes, I have had an opportunity of
thoroughly examining, is unfortunately in so deteriorated a
condition in many respects, and especially in regard to the
dermal membrane and pores, that I have been induced to
select G. Barretfi from which, to a great extent, to describe
the interesting and highly organized structures of this
genus ; and I have the advantage also in this species of
having a portion of a specimen which has never been de-
teriorated by drying, having been pickled in strong salt
and water immediately on being taken from the sea, by
my friend Mr. McAnclrew. and in this state it closely re-
sembles a mass of somewhat indurated animal liver.

The skeleton is composed of continuous fasciculi of stout
long spicula, which in massive specimens radiate from the
base to the outer surface of the sponge ; or if the species
be of an elongated form, from the central axis to the cir-
cumference, where in either case they terminate at the inner
surface of the crustular clermis, intermixing with, and
being firmly cemented to, the shafts of the expando-ternate
connecting spicula, which are attached to and firmly support

* " Polyparinm liberum, carnosum, tuberiforme intus cavum et vacuum, in
sicco durum ; externa superficic uiiclique porosa. Foramina poris niajora in
area unica orbicularo et laterali observata." (Lamarck, ' Ann. s. Vert.,' 2de
edit., ii, 593.

OF THE SPONGIAD.E. 169

the inner surface of the crustular clermis. Fio;. 354,
Plate XXVIII.

The organization of this external crust is exceedingly
interesting. The outer surface is composed of a uniform
thin pellucid dermal membrane, perforated with innumer-
able minute pores, variable in their diameter, and ap-
parently possessing the power of opening or closing at the
will of the animal. Immediately beneath the dermal mem-
brane there is a stratum of sarcode of variable thickness in
different species, and this stratum is permeated by numer-
ous short canals, connecting the external pores with the
intermarginal cavities which occupy, at nearly equidistant
points, the thick stratum of ovaria forming the inner layer
of the crustular dermis. In dried specimens, the positions
of the intermarginal cavities are usually indicated on the
surface of the sponge by a series of dimples or pits, fre-
quently assuming, by the contraction of the dermal mem-
brane, more or less of a stellated appearance. The proxi-
mal extremities of these organs is at the inner surface of
the stratum of ovaria, and the distal extremities at the outer
surface of the same stratum ; and this termination has
usually a greater diameter than the proximal end, which is
furnished with a stout contractile diaphragm or pyloric
valve.

The expando-ternate spicula, which are situated at the
distal extremities of the radial fasciculi of the skeleton,
diverge slightly from each other from their basal extremi-
ties, so that their triradiate heads, when firmly cemented to
the inner surface of the ovarian stratum, form a strong and
regular siliceous network, the points of the radii of each
being cemented by keratode to those of its next neighbour ;
and within the area of each of these meshes of the network
there is the proximal end of an intermarginal cavity, the
diaphragm of which frequently occupies the greater portion
of the area, having a much greater diameter than that of
the proximal orifice of the cavity, so that when fully opened
its orifice is quite equal to that of the intermarginal cavity.
The ovaries vary considerably in size in different species.
In the adult and prolific condition they have the form of a

170 ANATOMY AND PHYSIOLOGY

strong, thick- shelled, more or less globose ovarium, having
a funnel-shaped orifice at the apex, which communicates
with the central cavity, which, in the prolific state, is filled
with closely-packed minute vesicular bodies, very similar in
appearance to those contained in the ovaria of the Spon-
gillida?, but apparently more minute. In this condition of
the ovary its parietes are formed of acutely cuneiform
spicula, firmly cemented together by siliceous matter, the
united apices forming the inner surface of the ovarium,
while the united truncate bases form the external surface.
In the early and immature state of the ovaria these trun-
cated bases are not produced, and the young ovary has its
outer surface bristling with pointed spicula, which are most
acute in the youngest specimens, and becoming gradually
more obtuse as they approach maturity. After the prolific
contents of the adult ovary has been liberated, the internal
cavity is gradually filled up by the extension inwards of the
apices of the cuneiform spicula until it becomes eventually
a solid body ; and a similar secretion of siliceous matter is
also frequently continued at the outer surface until it often
assumes an irregular tuberous and quite abnormal ap-
pearance.

The ovarian stratum of the crustular dermis is princi-
pally composed of exhausted solid ovaria, but occasionally
near the outer surface of the stratum a few prolific ones
may be observed ; but the greater number of these bodies
and of those in an early stage of development, are situated
amid the deeply-seated portions of the sponge, scattered
irregularly over the sarcodous membranes and deeply im-
mersed in the sarcode. In the young state they each
appear to be surrounded by a firm stratum of sarcode,
which, from its perfectly smooth and circular form, is ap-
parently contained within a proper membrane, but in the
fully developed and in the exhausted ovaria this sarcodous
envelope is not observable. This description of the organi-
zation of the genus will apply equally well to any one of
the seven species with which I am acquainted, and also to
the nearly allied genus Pachymufisvta, excepting the mode
of the arrangement of the skeleton in the latter.

OF THE SPONGIAD^E. 171

Both the type specimens of Geodia in the Museum at
the Jardin des Plantes appear to have had large central
cavities, but I have not found similar excavations in other
species of the genus excepting in one instance, a Geodia
from Port Elliot, Australia ; the internal surface in each of
the three cases presents precisely the same appearance, a
simple irregularly matted surface of spicula and membranes
without any thickening of the tissues, and differing in no
respect from the surfaces of any of the smaller internal
cavities of the sponge. I am therefore inclined to consider
such excavations as abnormal occurrences, which are not en-
titled to be considered as of either generic or specific value.
Fig. 354, Plate XXVIII, represents a section at right
angles to the surface of Geodia Baretti, Bowerbank, MS.,

a, a, longitudinal sections of two of the intermarginal
cavities ; b, b, the basal diaphragms of the intermarginal
cavities ; c, c, the imbedded ovaria forming the dermal crust
of the sponge ; d, d, the large patento-ternate spicula the
heads of which form the areas for the valvular bases of the
intermarginal cavities ; e, c, recurvo-ternate spicula within
the summits of the great intercellular spaces of the sponge ;

f,f, portions of the interstitial membranes of the sponge
crowded with minute stellate spicula ; y, y, portions of the
secondary system of external defensive spicula X 50 linear.
See also Figs. 301, 302, Plate XIX. Fig. 301 represents
a small portion of the inner surface of the dermal crust
Geodia Barretti with two of the valvular membranes of the
proximal ends of the intermarginal cavities ; a, valve closed ;

b, valve partly open; c, portions of the patento-ternate spicula
imbedded in the tissues and forming the areas for the val-
vular terminations of the intermarginal cavities X 50 linear.

PACHYMATISMA, Bowerbank.

Skeleton composed near the external surface occasionally
of short fasciculi of siliceous spicula, disposed in lines
at about right angles to the surface of the sponge.
Central portion of the sponge unsymmetrical. Der-

172 ANATOMY AND PHYSIOLOGY

mis crustular, furnished abundantly with closely
packed ovaria. Ovaria siliceous, formed of cuneiform
spicula, firmly cemented together in lines radiating
from the centre of the ovary. Pores furnished with
cesophageal tubes, terminating in the distal extremity
of each intermarginal cavity. Intermarginal cavities
symmetrical, subcylindrical, with a pyloric valve at
the proximal end of each.

Type, Pachymatisma Johnstonia, Bowerbank.

Since the first publication of my description of the
sponge on which this genus is founded in the " Synopsis
Spongiarum" of Dr. Johnston's 'History of British Sponges/
p. 243, I have found it necessary to base the generic cha-
racters of the Spongiadse on the structural peculiarities of
the skeleton and reproductive organs. I have therefore
reconstructed the character of the genus in accordance with
this rule.

This genus is closely allied to Geodia in its organic
structure, but the difference in the arrangement of the
skeleton readily distinguishes them. The general aspect of
the species of each genus is also strikingly distinct. I am
acquainted with seven species of Geodia and three of Pachy-
matisma, and in every case the species may be readily
referred to its proper genus even by its general aspect.
All the species of either genus have a crustular dermis,
and the structures of the ovaria are also alike in each. I
have desciibed the anatomical peculiarities of the latter
organs so fully in the description of the generic characters
of Geodia as to render it unnecessary to treat of them
under the present circumstances. Fig. 353, Plate XXVIT,
a view of a section at right angles to the surface from
Pachymatisma Johnstonia, exhibiting the irregularity of the
interstitial structures immediately beneath the dermal
crust X 50 linear.

OF THE SPONGIAD^!. 173

ECIONEMIA, Bowerbank.

Sponge. Having a strong axial column or centre of closely
packed siliceous spicula disposed in lines parallel to
the long axis of the sponge, from which axial column
or centre a peripheral system of spicula radiates at
about right angles. Distal ends of the radii furnished
more or less with tern ate connecting spicula, the
radii of which are disposed immediately beneath the
dermal membrane.

Type, Ecionemia acervus, Bowerbank, MS.

This genus differs from Dictyocylindrus in having the
axial column composed of a dense mass of parallel spicula
instead of a column formed of an open network of spicula ;
and the peripheral system is also different, inasmuch as it
is essentially a portion of the interstitial system of the
sponge, and not more especially a defensive system as it
appears in Dictyocylindrus ; in no species of which genus
has there ever yet been found ternatc spicula at the
surface, while in Ecionemia acervus, the type species of
the genus, they are abundant.

The structure of the peripheral system exhibits a close
alliance with the genera Pachymatisma and Tetliea. Ecio-
nemia differs from Geodia and Pachymatisma in the total
absence of the siliceous ovaries, and of the crustular dermal
coat formed principally of those bodies in the last-named
genera. There are also no cylindrical valvular inter-
marginal cavities, and the ternate apices of the connecting
spicula appear always to be applied to the inner surface of
the dermal membrane. This arrangement of the tissues
therefore forms a natural transition from Pacliymatisma to
Tef/tea, in some species of which genus the ternate spicula
are found without the dermal membrane in the porrecto-
ternate form, and are adapted to defensive purposes, while
in others they occur immediately beneath it as patento-
ternate connecting spicula. I have therefore assigned this
genus a position between Pacliymatisma and Dictyocylin-

174 ANATOMY AND PHYSIOLOGY

clrus. Fig. 355, Plate XXVIII, represents a view of a
section at right angles to the surface exhibiting the radial
fasciculi of the peripheral system with the ternate apices of
the spicula immediately beneath the dermal membrane
X 50 linear.

We have no British species of this genus ; the type
species, Ecionemia acervus, Bowerbank, MS., is in the
Museum of the Royal College of Surgeons of London.

ALCYONCELLUM, Quo?/ et Gaimard (Euplectctta, Owen).

Professor Owen, in his paper on Euplectella aspergillum,
Owen, communicated to the Zoological Society January
26, 1841, and published in the ' Transactions of the Zoolo-
gical Society of London,' vol. iii, part 2, p. 203, pi. xiii,
appears to have fallen into a singular number of errors in
the course of his description of this beautiful sponge. He
has, in the first place, designated it as belonging to the
Alcyonoid family, apparently only because it is cylindrical
in form and reticulate in structure, but without the
slightest reference to the polyps that must necessarily cha-
racterise an Alcyonium ; and he proceeds in his descrip-
tion to describe the base of the sponge as its apex and the
apex as its base. The author then notices the first speci-
men of this genus that was made known to us by MM.
Quoy and Gaimard, in the ' Zoologie de 1J Astrolabe/ Svo,

1833, p. 302, planches fol. Zoophytes, fig. 3, pi. xxvi,
but unfortunately mistakes the generic name Alci/onceJlmn,
applied to the sponge by the French authors, for Alcyonel-
lum ; and having mistaken its name, its base, and its apex,
he proceeds to reason on its generic characters thus : — " If
the basal aperture of the cone were open, the resemblance
to some of the known reticulate Alcyonoid sponges would
be very close, especially to that called Alcyonellum gela-
tinosum by M. de Blainville, ' Manuel d'Actinologie/ Svo,

1834, p. 529 (Alcyonellum speciosum, Quoy et Gaimard):
its closure by the reticulate convex frilled cap, in the pre-
sent instance, establishes the generic distinction ; and in

OF THE SPONGIAD^B. 175

the exquisite beauty and regularity of the texture of the
walls of the cone, the species surpasses any of the allied
productions that I have yet seen or found described. I
propose, therefore, to name it Euplectella aspergillum." In
note 5 appended to this paper, Professor Owen also says,
" If the recognition of the generic or specific identity of
the specimen here figured be impracticable by reason of
its mutilated condition, the generic name applied to it
cannot be adopted while the Lamarckian genus of fresh
water polyps, Alcyonetta, is retained in Zoology." Now as
it is manifest that the reasoning of Professor Owen in
favour of his proposed genus Euplectella is based, not upon
one only, but upon a series of errors, and as he has not
attempted to characterise his own genus, while that of
Alcyoncellum, Quoy et Gaimard, is regularly described in
the ' Histoire Naturelle des Aniuiaux sans Vertebres ' by
Lamarck, 2nd Edit., vol. ii, p. 589, printed in 1836, it is
evident that the generic name of the French authors must
take precedence of that proposed by Professor Owen.

The following is the generic description of MM. Quoy
et Gaimard :

" Genre ALCYONCELLE (Alcyoncellum).

Spongiare, lamelleux, dont la charpente est formee de filets
tres delies, accoles les uns aux autres et entre croises
de maniere a former des mailles nombreuses, arron-
dies, assez regulieres, et semblables a celles d'une
dentelle."

In this generic description the material of which the
sponge is formed is not in the slightest degree indicated,
and the description of its structural peculiarities is so
general that it will apply equally well to almost every
known fistulose sponge. I have therefore thought it neces-
sary to arrange the sponges of this genus with their con-
geners in material and mode of construction, and to recon-

176 ANATOMY AND PHYSIOLOGY

struct the generic characters so as to endeavour to limit
the genus within definite bounds. I propose therefore to
substitute the following characters for those of the French
authors.

ALCYONCELLUM, Quoy et Gaimanl.

EUPLECTELLA, Owen.

Sponge fistulate ; fistula single, elongate, without a massive
base. Skeleton : primary fasciculi radiating from the
base in parallel straight or slightly spiral lines ; secon-
dary fasciculi at right angles to the primary ones.
Oscula congregated, with or without a marginal
boundary to their area.

Type, Alcyoncellum corbicula, Quoy et Gaimard.

The congregation of the oscula in Alcijoncellum corbicula
and asperyillum is not a character peculiar to those sponges.
A similar mode of arrangement exists in several species of
Geodia. In G. yibberosa, in the Museum of the Jardin
des Plantes at Paris, they are congregated in an area with
a well-defined boundary, and in specimens of G. Barretti
in my possession they are situated in deep depressions or
cavities on the surface of the sponges ; and these cavities
or areas are not uniform in either shape or size ; so we may
infer that the presence in some species of Alcyoncellum of a
well-defined marginal boundary to the oscular area, and its
absence in other species, amounts to a specific difference
rather than to a generic distinction ; but in either case the
oscular are congregated at the distal extremity of the
sponge, and the areas of its parietes are the inhalant por-
tions of the animal. The inhalation and exhalation of
water is precisely on the same principle as that which
obtains in Gra/itia ciliala ; the whole of the parietes are
appropriated to inhalation, the incurrent streams are passed
through the interstitial cavities and discharged into a com-
mon cloaca, and the effete stream ejected at the distal

OF THE SPONGIAD^E. 177

extremity of the sponge ; the essential difference being
that in Grantia the distal end of the cloaca is open, and in
Alcyoncellum it is partially closed by a cribriform veil, the
orifices of which appear to be the true oscula of the sponge.
And this opinion is justified by the structure of the
numerous cloacae in the closely-allied genus Polymastia,
where we find the orifices through which the incurrent
streams are poured into the cloaca permanently open.

All the known species of this genus appear to consist of
a single fistulose body, and some of them are apparently of
a parasitical habit. Alcyoncellum aspergillum (Euplectella
aspergilhnn, Owen) especially is furnished with numerous
recurvo-quaternate spicula at its base, by which it attaches
itself to sponges or other bodies. These prehensile organs do
not appear in all the species of the genus, and in one perfect
and beautiful specimen in the Museum of the Jardin des
Plantes at Paris the base is closed, and is entirely destitute of
prehensile spicula. The attachment of the sponge is partly,
on one side, in the form of a thick incrustation, and partly,
close to the base, by a similar patch of thickened tissue.
There is also another striking difference in its structure,
and that is the absence of the raised margin to the oscular
area at the apex of the sponge. In other structural cha-
racters it agrees exceedingly closely with A. aspergillum.

Fig. 356, Plate XXIX, is a view of a small portion of
the surface of Mr. Cuining's specimen of Alcyoncellum
aspergillum, exhibiting the mode of disposition of the in-
halant areas ; a, the primary fasciculi of the skeleton ; 6,
the secondary fasciculi, plus about 5 linear. Fig. 357 re-
presents the congregated oscula within their marginated
area at the distal termination of the sponge. Natural
size.

POLYMASTIA, Boiverbank*

Skeleton. Basal mass. Central portion consisting of a
plexus of contorted anastomosing fasciculi, resolving
themselves near the surface into short straight bundles

178 ANATOMY AND PHYSIOLOGY

disposed at nearly right angles to the surface. Oscula
congregated, elevated on numerous long fistulse. Fis-
tulse composed of numerous parallel fasciculi, radiating
from the base to the apex of each in straight or slightly
spiral lines.

Type, Polymastia mammillaris, Bowerbank.

This genus is closely allied to Alcyoncellum, Quoy et
Gaimard ; the principal difference being that in the latter
the sponge always consists of a single fistula, while in the
former it is constructed of a basal mass from which nume-
rous fistula?) emanate. The form and structure of the
fistular organs in each genus very closely resemble each
other. Beside these structural differences, there are others
of a less striking description, that strongly indicate the
necessity for generic separation. Thus in Alcyoncellmn cor-
bicida, in the Museum at Paris, and Eiiplectella aspen/ilium,
Owen, there are an abundance of interstitial spicula of rec-
tangulated hexradiate forms, which are very characteristic
of those species, while the British species of Polymastia
with which we are acquainted appear to be totally destitute
of these complicated and beautiful forms of spicula. I have
therefore thought it desirable, notwithstanding the close
agreement that exists in the structure of their fistulse, that
a generic distinction should be established between them.

Halichondfia mammillaris, Johnston, is the best type of
the genus Polymastia. Tho whole of the parietes of these
elongated fistulse are inhalant. In some specimens of P.
mammillaris dredged in Vigo Bay by my friend Mr.
McAndrew, the open pores are exceedingly numerous, and
the exhalant organs are as distinctly shown to be confined
to the distal extremities of the fistulse.

Fig. 358, Plate XXIX, represents a view of a small
portion of the side of one of the large cloacas of Polymastia
robusta, Bowerbank, exhibiting the structure and mode of
disposition of the longitudinal skeleton fasciculi, X 25
linear.

OF THE SPONGIAD^l. 179

HALYPHYSEMA, Bowerbank.

Sponge. Consisting of a hollow basal mass, from which
emanates a single cloacal fistula. Skeleton. Spicula
of the base disposed irregularly ; spicula of the fistula
disposed principally in lines parallel to the long axis
of the sponge, without fasciculation.

Type, Halyphysema Tumrmowiczii, Bowerbank.

In its form and habit the type of this genus closely re-
sembles Polymastia brevis ; but the total absence of fasci-
culi in its construction at once marks it as a distinct genus,
although a closely allied one. The type species, H. Tmna-
nowiczii, is remarkable as being the smallest known British
sponge ; it rarely exceeds a line in height. .The base of the
sponge resembles in form the half of an orange cut at right
angles to its axis, and the fistular cloaca is usually dilated at
its distal extremity. I have been unable to detect either
oscula or pores in any of the numerous specimens I have
examined ; but from the general accordance in structure
with the genera Alcyoncellum and Polymastia, there is a
strong presumption that the oscula will prove to be congre-
gated at the distal extremity of the cloacal fistula, as in
those genera.

Fig. 359, Plate XXX, represents a complete specimen of
Halyphysema Tumanowiczii, (pronounced Tumanovitchii)
based on the stem of a Zoophyte, exhibiting the irregular
longitudinal disposition of the skeleton spicula, X 175
linear.

CIOCALYPTA, Bowerbank.

Skeleton. Composed of numerous closed columns, each
consisting of a central axis of compact, irregularly
elongated, reticulated structure, from the surface of

180 ANATOMY AND PHYSIOLOGY

which radiate, at about right angles, numerous short
simple cylindrical pedicles, or stout fasciculi of closely
packed spicula ; the distal ends of each pedestal sepa-
rating and radiating in numerous curved lines which
spread over the inner surface of the dermal membrane,
separating and sustaining it at all parts at a consider-
able distance from the central axis of the skeleton.

Type, Ciocalypia pcnicittus, Bowerbank.

This genus is allied, by its structural peculiarities, to a
certain extent, to Dictyocylindrus, Bowerbank, Hyalonema,
Gray, and Alcyoncettum, Quoy et Gaimard. The central
axial column of the skeleton is composed of elongated stout
reticulations of siliceous spicula, closely resembling the cor-
responding tissues of the axial column of a Dictyocylindrus ;
but the space between the surface of the column and the
inner surface of the dermis is not filled, as in that genus,
by the usual interstitial structures of the sponge, it is com-
pletely and widely separated from the dermis in a manner
very similar to that of the structure of the greatly elongated
cloacal appendage of Hyalonema mirabilis, as it appears in
its present condition in the most perfect specimens in the
British Museum and in the collection of Dr. Gray. There
is this difference between the structures of the two genera.
The coriaceous dermis surrounding the beautiful spiral
axial column of Hyalonema is very thick, and is abundantly
furnished with projecting oscula ; and it does not present
any indications of lateral pedestals, either on its inner surface
or on the surface of the axial column, while these organs
are abundant in C. penicillus ; and its dermis also is com-
paratively thin and delicately reticulated.

The dermal portion of the sponge in C. penicillus, and
the reticulated tissues on its inner surface, closely resemble
the corresponding tissues in Alcyoncellum in their structure.
The pores, in number, size, and mode of distribution, are
very similar to those of Poh/mastia robusta, Bowerbank ;
but the stratum of these reticulated skeleton structures is
not so thick in proportion, and in Alcyoncellum and Poly-

OF THE SPONGIAD^E. 181

mastia there is no central axial column. I could not detect
interstitial membranes in any part of the space intervening
between the axial column and the dermis in C. pencil/us,
but the skeleton column is permeated by numerous inter-
stitial canals.

The structure of the short pedestals passing from the axial
column to the inner surface of the dermis is different from
that of the axis ; the spicula composing them are parallel
to each other, and they are firmly packed together. The
bases of the pedestals arise from the surface and from within
the substance of the central column, with which they appear
to have no further connection than that which is necessary
to secure them firmly in their respective positions. Their
apices present a very beautiful appearance, spreading out
towards the inner surface of the dermis in curves, in the
direction of angles of about 45 degrees, diverging in every
direction over its inner surface, which, when viewed with a
microscopic power of about 100 linear, resembles an elabo-
rately and beautifully groined roof of a Gothic crypt where
the pedestals impinge.

Fig. 360, Plate XXX, represents a longitudinal section
through the central axis of one of the elongate cloacal
portions of the sponge, exhibiting the central column and
the small cylindrical pedestals or short fasciculi of closely
packed spicula, each terminating at the outer surface of the
dermis of the sponge, natural size. Tig. 361, exhibits a
section of the specimen represented by Fig. 360, at about
the middle of the cloacal column, showing the mode of the
radiation of the distal ends of the small pedestals on the
inner surface of the dermis, X 25 linear.

TETHEA, Lamarck.

. The following are the generic characters given by
Lamarck, in his ' Anim. sans Vert.' 2nd edit. ii. 384 : —

182 ANATOMY AND PHYSIOLOGY

"TETHIE (Tetliea).

" Polypier tubereux, subglobuleux, tres fibreux mterieure-
ment ; a fibre subfasciculees, divergentes ou rayon-
nantes de 1'interieur a la circonference et agglutinees
entre elles par un pen de pulpe ; a cellule dans un en-
croutement cortical quelquefois caduc. Les oscules
rarement perceptibles."

Dr. Johnston's version of the generic characters differs
slightly from Lamarck's. They are as follows : —

" Sponge tuberous, suborbicular, solid and compact, invested
with a distinct rind or skin, the interior sarcoid loaded
with crystalline spicula collected into bundles and
radiating from a more compact nucleus to the circum-
ference. Marine."

It is nruch easier to find faults in the generic characters
of both the authors quoted, than it is to improve them.
The extreme simplicity of the structural characters of Tetliea
is a strong temptation to endeavour to multiply them ; but
in doing so, Dr. Johnston has introduced two — the struc-
ture of the dermal portion of the sponges, and the tuberous
nature of its surface — which are not common to all the
known species. If we consider the word " tuberous " in
the usual English acceptation of the word, as a body " full
of knobs or swellings," then very few or perhaps none of
the species of Tetliea would, in their natural condition,
exhibit this character, but all of them would be in a greater
or less degree subglobular. Dr, Johnstone's description of
Tetliea was founded on the structure of T. lyncwrium only,
and in this species the " thick rind ' is very distinctly to
be seen, but in other species this structure is totally
wanting. It therefore ceases to be of value as a generic
character, and becomes a specific one only. Under these"
circumstances I propose the following modification of the
previously published generic characters : —

OF THE SPONGIAU^. 183

Sponge massive, suborbicular. Skeleton consisting of
fasciculi of spicula. Fasciculi radiating from a basal
or excentrical point to the surface. Intel-marginal
cavities unsymmetrical, confluent. Propagation by
internal or external gemmulation.

Types, Tethea lyncurium, Linnaeus, &c.
„ cranium, Lamarck.

This genus affords ns one of the few instances in which
we may avail ourselves of external form as a generic
character; but even in Tct/iea we approach exceptions to
the rule in the depressed form of T. Collinysii, Bower-
bank, as exhibited in the only perfect specimen of that
species which I have seen, and in the still more depressed
form of T. spinularia, Bowerbank.

Although the skeleton structures in the species of this
genus differ to an exceedingly slight extent, the subsidiary
spicula vary exceedingly in the different species. In some,
tern ate spicula are numerous, and in others they are entirely
absent, and stellate forms of spicula occur in many varieties
of form.

The sponges of this genus appear to be highly organized.
Audouin and Milne- Edwards saw the oscula open and the
excurrent streams in action, and I have seen the same
myself in a specimen of T. lyncurium. My friend Mr.
George Clifton, of Freemantle, Western Australia, in a
letter dated 25th January, 1861, writes, "I have sent you
several fine specimens of Tethea. When these animals
are first taken out of the water they are of a brilliant orange
colour, and commence squirting water from the oscula
situated on the centre of the upper surface ; they also
contract considerably, but on being replaced in their native
element they regain their natural size and reabsorb water."

The mode of propagation varies in different species. In
T. cranium and simillima, Bowerbank, MS., it is by internal
gemmulation, in T. lyncurium by external gemmulation, and
"in some other species the mode is not apparent.

Figure 362, Plate XXXI, represents a portion of a slice
at right angles to the surface, from Tethia cranium, showing

184 ANATOMY AND PHYSIOLOGY

the fasciculi of defensive spicula (a) and the mode in which
they are supported by buttresses of spicula beneath the
surface of the sponge at b; c> the recurvo-ternate spicula,
X 50 linear,

HALICNEMIA, Bowerbank.

Skeleton formed of a single superior stratum of spicula
radiating from the centre to the circumference of the
sponge at about its middle, and of an inferior stratum
of spicula distributed without order.

Type, Halicnemia patera, Bowerbank.

The nearest alliance to this genus appears to be Tethea,
in which the skeleton is formed of numerous fasciculi of
spicula radiating from the centre to all parts of a spherical
or elliptical mass ; while in Halicnemia the radiating fas-
ciculi are confined to a common plane, beneath which there
is a second stratum of spicula, which fills the space beneath
the radial stratum and the lower surface of the sponge, but
without being disposed in order; and the spicula of the
inferior stratum differ materially in form and proportions
from those of the superior one.

In all the specimens of this genus that I have seen there
is a small pebble imbedded in the centre of each sponge,
from the surface of which the basal fasciculi of the radial
series emanate ; but although this appears to be the estab-
lished habit of this species, it is advisable not to consider
it as a generic character, although it may eventually prove
to be that the pebble is as much a portion of the skeleton
of the animal as the grains of extraneous matter which are
taken up by and become imbedded in the keratose fibres
of the genus Dysidea. Fig. 363, Plate XXXII, repre-
sents a portion of a section at right angles to the surface of
the sponge, exhibiting the mode of disposition of the
spicula of the skeleton X 25 linear. Eig. 364 is a view

OF THE SPONGIADJE. 185

of a portion of the same section taken at a, fig. 363, X
108 linear.

DICTYOCYLINDRTJS, Sowerdank.

Skeleton. Without fibre. Composed of a loosely com-
pacted columnar axis of spicula, disposed principally
in the direction of the line of the axial column, from
which a peripheral system of long single or fascicu-
lated defensive spicula radiate at right angles to the
axial column.

Type, Dictyocylindrus hispidus, Bowerbank.

Halichondria Jmpida, Johnston, and Spongia stuposa,
var. damicornis, Montagu, are excellent types of the peculiar
mode of arrangement of the spicula which characterises
this genus. The skeleton consists of a central column of
large elongate spicula, disposed principally in the line of
the axis of the sponge and at a slight angle to it, approach-
ing in form an irregular cylinder of network of elongated
meshes, rarely exhibiting an appearance of horny fibre, but
formed for the most part of spicula cemented together near
their terminations. Towards the base of the sponge the
horny substance surrounding the spicula is sometimes so
thick as to simulate a proper horny fibre ; but if it be
carefully traced, it will always be found to be dependent
on the spicula ; where their course is abruptly terminated
the horny structure also terminates ; whereas in true horny
fibrous structures which contain spicula the course of the
fibre is continuous and uniform whether the spicula be
present or deficient, and in the newly produced fibre the
latter is generally the case.

The structure of the skeleton in this genus differs from
that of Halichondria oculata, Johnston, (Chalina oculata,
Bowerbank), in the regularly elongate disposition of the
spicula of the skeleton ; and the spicula are necessarily
very much larger and longer than those included in the

186 ANATOMY AND PHYSIOLOGY

close fibrous network of C. ocidata -, and it is still further
removed from the horny fibrous structure of Halichondria
cervicornis, Johnston, ' Hist. Brit. Sponges,' pi. iv. The
axial column of this genus differs strikingly from that of
the strong, closely packed axis of jEcionemia, and the peri-
pheral system of spicula are never furnished with ternate
connecting spicula. All the species of this genus I have
hitherto seen are more or less ramous in form. Fig.
365, Plate XXXII, represents part of a small branch of
Dictyocylindrus rugosus, Bowerbank, exhibiting the radiating
structure of the defensive fasciculi, X 50 linear ; a, part of
the central axis of spicula. Fig. 366, Plate XXXIII,
represents part of a section through the axial column of
Dictyocylindrus ramosus, showing the elongo-reticulate
structure of the skeleton of the sponge, X 50 linear.

PHAKELLIA, Bowerbank.

Skeleton. Composed of a multitude of primary cylindrical
axes, radiating from a common base and ramifying
continuously, from which emanate at about right
angles to the axes a secondary series of rainuli, which
ramify continuously as they progress towards the
surface, but never appear to anastomose.

Type, Phakettia ventilabrum, Bowerbank.

I know of no other species, either British or foreign,
that possesses the peculiar conformation that distinguishes
the sponge that is the type of this genus. The primary
cylindrical axes very closely resemble those of Dictyocylin-
drus, but in that genus the spicula radiating from the axes
are separate and distinct, each having its proximal end
based on the primary cylinders of the skeleton, and its
distal one reaching nearly to, or passing through the
dermal membrane of the sponge ; or if they be fasciculated,
the fasciculi are simply plumose, and in no case with which
I am acquainted at all raniulous. In PhahelRa the secon-
dary skeleton is formed of distinct slender branches, each

OF THE SPONGIADjE. 187

composed of numerous spicula ramifying continuously, and
each ramulus increases in size and the number of its
spicula as it approaches the surface of the sponge. Single
spicula are frequently projected from the ramuli in an
ascending direction at an angle of a few degrees, and at
their distal terminations at the surface of the sponge ;
the whole of the terminal spicula radiate more or less at
angles from, their axial line, and passing through the
dermal membrane form the external defences of the
sponge. Although constantly ramifying and freely inter-
mingling, I have never detected them anastomosing. The
term Pkakettia is applicable to both the primary and
secondary ramifications of the skeleton. The type of this
genus is Halicbondria ventilabrum, Johnston. I have not
yet met with an exotic species of the genus. Fig. 367,
Plate XXXIII, represents a longitudinal section of one of
the primary radial lines of the skeleton structure, exhibiting
the slender secondary radiations of the skeleton ; a, part of
the primary axial portion of the skeleton ; b, dermal mem-
brane, X 50 linear.

The genera Microciona, Hymeraphia, and Hymedesmia
form a group essentially different in structural character
from the other genera of the Spongiadae ; but they are
closely allied to each other by the peculiar characters of
their basal membranes in conjunction with the other parts
of the skeleton. From the nature of their structures, the
species generally assume a thin coating form and are often
very minute.

In most of the genera of SpongiadsB the basal membrane
of the sponge ceases to be of marked importance after the
earliest stages of its development, but in these genera it
continues throughout the whole existence of the sponge to
form an important part of its skeleton structure. It is a
common base whence spring the whole of the other com-
ponent parts of the skeleton ; and its importance is further
indicated by its also being the common base in some
•species of the internal as well as the external defensive
picula of the sponges in which those organs occur.

188 ANATOMY AND PHYSIOLOGY

MICROCIONA, Bowerbanh.

Skeleton. A common basal membrane, whence spring at
or about right angles to its plane numerous separate
columns of spicula intermixed with keratode, furnished
externally with spicula which radiate from the columns
at various angles towards the dermal surface of the
sponge.

Type, Microciona atrasan guinea, Bowerbank.

The skeleton of the type of this genus, M. atrasawf/uinea,
is different from that of any other genus of sponges that I
have hitherto seen. It consists of numerous, nearly equi-
distant, short, straight, separate columns of spicula and
keratode from all parts of the sides of which spring stout,
long, curved, fusiformi-attenuato-subspinulate spicula, the
convex side of each spiculum being outward, and each
column terminates with five or six of these spicula disposed
in the same manner and at the same angle to the axial line
of the column, that is from about twenty to forty-five
degrees. The proportions of the skeleton-columns vary in
different species. In M. atrasanguinea they are short,
stout, and exceedingly well defined. In M. ambit/ua they
are short and indistinctly produced, and in M. carnosa they
are long, slender, flexuous, and frequently branched ; but
however they may vary in their proportions in different
species, their normal character, both as regards structure
and position in the sponge, is always preserved. Fig. 368,
Plate XXXIII, represents a single column of the skeleton
of Microciona atrasanyuinea, Bowerbank, showing its struc-
ture and the proportions and positions of the external
defensive spicula, X 175 linear. Fig. 369, Plate XXXIV,
represents a section at right angles to the surface of the
sponge exhibiting the columns of the skeleton in situ ; a, the
plane of the dermal membrane with groups of tension
spicula.

OF THE SPONGIAD^E. 189

Genus — HYMERAPHIA, Bowerbank.

Skeleton. A single basal membrane, whence spring nu-
merous large separate spicula, which pass through the
entire thickness of the sarcodous stratum to, or beyond
the dermal surface of the sponge.

Type, Hymeraphia stellifera, Bowerbank.

This genus is nearly allied to Microciona, but is more
simple in its structure ; as in place of the columns of the
skeleton compounded of keratode and spicula cemented
together, and emanating from a common basal membrane
as in the latter genus, we find single spicula only, devoid
of keratode and based on a common membrane, whence
they pass through the entire substance of the sponge ; and
in all the species at present known, they penetrate the
dermal membrane and project beyond its surface to a con-
siderable extent, thus combining the two offices of skeleton
and external defensive spicula. These organs are there-
fore, as compared with the skeleton spicula of other mem-
bers of the Spongiadse, and to the entire mass of the
sponges to which they belong, of exceedingly robust pro-
portions ; their length being frequently twice that of the
entire thickness of the sponge.

These peculiarities of structure indicate a common habit
of extreme thinness in the species, and such is in reality
the condition of those with which we are acquainted.
Fig. 370, Plate XXXIV, represents a section of Hymera-
plua stclUfcra, Bowerbank, showing the large bulbous
skeleton spicula in situ, their apices forming the external
defences ; a, the stelliferous internal defensive spicula ele-
vated by a grain of sand beneath the basal membrane,
X 108 linear. Fig. 34, Plate I, exhibits one of the stel-
liferous defensive spicula, X 260 linear.

190 ANATOMY AND PHYSIOLOGY

HYMEDESMIA, 'Bowerbank.

Skeleton. A common basal membrane sustaining a thin
stratum of disjoined fasciculi of spicula.

Type, Hymedesmia Zetlandica, Bowerbank.

The species on which this genus is founded very closely
resembles in habit and general appearance those of the
genera Microciona and Hymeraphia, and in regard to the
special offices of the basal membrane, it assimilates with
them completely. But it differs from them, inasmuch as
the spicular portions of the skeleton do not emanate imme-
diately from the basal membrane, but are recumbent on it
in the form of disjoined fasciculi of spicula. But although
different from them in this important respect, the close
alliance with them is indicated by the common habit of the
possession by the basal membrane of the whole, or nearly
so, of the defensive spicula of the sponge ; indicating the
common property of extreme thinness of structure which
exists in these genera.

The free condition of the fasciculi of the skeleton con-
nects this genus in some degree with the Halichondroid
genera of sponges, but there are none of the species of those
genera in which the fasciculi of the skeleton are separate
from each other. The nearest allied genus in that direc-
tion appears to be Hymeniaddon. Fig. 371, Plate XXXV,
exhibits the disjoined fasciculi of the skeleton in situ, in
Hymedesmia Zetkmdica, X 108 linear; and Fig. 296
Plate XVIII, represents a small portion of the inner surface
of the dermal membrane of the same sponge, showing the
fasciculation of the simple bihamate spicula, the equi-
anchorate ones dispersed singly on the membranes, and the
large attenuato-acuate entirely spined defensive ones in situ,
X 308 linear.

OF THE SPONGIAD^E. 191

Suborder II. Spiculo-membranons skeletons. Composed
of interstitial membranes, having the skeleton spicula
irregularly dispersed on their surfaces.

The prominent character of this Order is that the spicula
of the sponges composing it do not assume either the
radiate, fasciculate, or reticulate structural arrangement.
The distribution of the spicula on the interstitial mem-
branes being without any approximation to order.

HYMENIACIDON, Boiccrbank.

Skeleton without fibre, spicula without order, imbedded in
irregularly disposed membranous structure.

Type, Hymeniacidon carmcuta, Bowerbank.

In nymemacidon the spicula are subordinate to the mem-
branous structure, they follow7 its course and are imbedded
without order on its surface. The contrary is the case in
Halicltondria. The network of spicula in that genus,
although irregular, is decidedly the predominant structure,
and the membranous tissues are secondary to it, and exist
only as interstitial organs. The larger and stouter of the

«/ O O

spicula in Hymeniacidon, although dispersed amid the
slender ones, may be considered as the representative of
the skeleton spicula, while the slender ones are truly those
of the membranes, the tension ones.

In some species the interstitial tissues are constructed
diffusely, as in H. caruiiada, while in other species, as in
H. suberea (Halichondria suberca, Johnston) and a few
other closely allied species, they are more than usually
compact, so that in the dried state the texture of these
sponges are very like that of fine hard cork. From this
peculiarity of their appearance in the dried condition, and
the exceeding compactness of their structure, I was formerly
inclined to believe them to be generically different from the

192 ANATOMY AND PHYSIOLOGY

great mass of the species of Hymeniaddon, and I accord-
ingly inserted them in the list of British sponges, published
in the " Report of the Dredging Committee" in ' the Reports
of the British Association' for I860, under the titles of
Halina siiberea, fens, &c. ; but a closer examination of
their internal structure has convinced me that their only
real difference from the other species of Hymeniaddon is
in their greater compactness of skeleton structure, and
I have accordingly removed those species to the genus
Hymeniaddon.

In the greater number of the species of this genus the
tension spicula are of the same form as those of the skeleton,
and are only to be distinguished from them by their greater
degree of tenuity, but in a few of the known species they
are different both in size and form.

The mode of propagation in all the species in which I
have found the reproductive organs, appears to be by
internal gemm illation. In H. carnosa and several other
species of the genus they are simple, spherical, aspiculous,
membranous vesicles, filled with round or oval vesicular
molecules. The genus Halisarca, Dujardin, was supposed
by both that author and Dr. Johnston to be entirely des-
titute of spicula ; but I have, since the publication of the
' History of the British Sponges/ found them in H. Du-
jardinii in abundance. They are so minute and so com-
pletely obscured by the surrounding sarcode, that they can
rarely be detected in either the living or the dead specimens
when examined in water ; but if a portion of the sponge be
dried on a slip of glass and covered with Canada balsam,
they may be detected by transmitted light and a power of
400 linear in considerable numbers, dispersed on the inter-
stitial membranes of the sponge. This genus will therefore
merge in that of Hymeniaddon, with which it agrees in
every structural peculiarity. Fig. 372, Plate XXXV,
exhibits the dispersed condition of the skeleton spicula on
the interstitial membranes of a specimen of Hymeniaddon
caruncuJa, X 108 linear.

SPONGIAD^E. 193

Suborder III. Spiculo-reticulate skeletons. Skeletons
continuously reticulate in structure, but not fibrous.

Halichondria.
Hyalonema.
Isodictya.
Sponyilla,

The sponges of this suborder vary in the different genera
to a great extent in the mode of the construction of the
skeleton, but in all cases the spicula are the dominant
material; their terminations overlap each other, and they
are cemented together by keratode. The reticulations thus
formed sometimes consist of a single series of spicula, at
other times they are very numerous, and are crowded
together in the manner of elongated fasciculi.

The genera Halichondria and Isodictya are exceedingly
rich in species, but the inconvenience attending their dis-
crimination arising from their number may be remedied to
a great extent hereafter by subdivisions of each genus, based
on the characteristic forms of the spicula of their respective
skeletons. The structural distinction between Halichondria
and Isodictya is so well marked as to render the recog-
nition of each comparatively certain and easy. The skeletons
of the species of the latter genus, generally speaking, are
very much more slight and fragile than those of the former
one, and the same rule obtains to a great extent as regards
the comparative size of their spicula, and in many species
of Isodictya they are very minute. Hyalonema and Spon-
gilla are readily to be distinguished by the peculiarities of
their structure and localities.

The genus Halichondria, as constituted by Dr. Fleming
in his ' History of British Animals/ and adopted by Dr.
Johnston in his ' History of British Sponges,' contains
species which differ exceedingly in their mode of organiza-
tion. Thus, if we take H. panicea of Johnston, which is
undoubtedly the " sponge-like crumb of bread " of Ellis,

13

194 ANATOMY AND PHYSIOLOGY

and the older authors, and therefore the proper type of the
genus, we find the skeleton destitute of fibre, but composed
of an irregular network of spicula cemented together at their
apices by keratode. If we examine the well-known branching
sponge so common on all our coasts, Halichondria oculata
of the same author, we find an abundance of keratose fibre
containing spicula deeply imbedded in its substance, but
not necessarily uniting at their apices, and the network of
the skeleton is not irregular as in the first instance, but on
the contrary is more or less symmetrically disposed in all
parts of the sponge. If we take Halichondria suberea of
the same authors we find neither network of spicula nor a
keratose fibrous structure, but apparently an amorphous
sarcoid mass containing spicula and membranes, on which
the former are dispersed without any order or connection.
As we extend our researches among the other British
species of Fleming's genus Halichondria, other striking
and permanent variations in the arrangement of their
skeleton tissues present themselves. Their great differences
in structure therefore afford ample grounds for the division
of the species comprehended under Halichondria as consti-
tuted by Fleming into a series of genera, having each for
its base a separate type of organization ; and as the vari-
ations in structural character, some of which are mentioned
above, are both numerous and strikingly characteristic, I
propose to limit the genus Halichondria to those species
only, which agree in their organization with H. panicea of
Johnston, and to distribute the remaining species in other
genera, the distinctive characters being in all cases based
primarily on the different modes of the organization of the
skeleton of the animal, and when necessary taking in aid
such other organic characters as may be found available for
the purpose of accurate discrimination. I therefore propose
to limit the genus Halichondria to those sponges only, that
exhibit the following characters.

OF THE SPONGIADyE. 195

HALICHONDRIA, Fleming.

Sponge. Skeleton without fibre ; composed of an irregular
polyserial network of spicula cemented together by
keratode.

Type, Halichondria panicea, Johnston.

The anatomical structure of the group included under
this genus is distinct and unmistakeable. There is no fibre
whatever, the skeleton being formed of spicula collected
into bundles of a greater or less number cemented together
by keratode, but which substance does not extend beyond
the space occupied by the respective bundles ; and when
parts of the reticulated skeleton are formed of single series
of spicula only, they are simply cemented together at their
points, and the reticulated skeleton thus formed has no
definite arrangement.

In some species of the genus the reticnlar character of
the skeleton is much more distinct than in others. //.
vanicea, although the type of the genus is by no means the
best specimen of its character. Fig. 300, Plate XIX, repre-
sents a section of //. panicea at right angles to its surface,
md Fig. 303, the reticulations supporting the dermal mem-
brane, X 108 linear. Fig. 373, Plate XXXV, represents
a section at right angles to the surface of a specimen of
Halichondria incrustans, Johnston, X 50 linear, a better
type of the structural character of the genus than //.
panicea.

HYALONEMA, Gray.

Dr. Gray has characterised this genus in his descriptions
of genera of Axiform Zoophites, or Barked Corals, as
" coral subcylindrical, rather attenuated, and immersed in
a fixed sponge. Axis in the form of numerous elongated,
slender, filiform, siliceous fibres, extending from end to end

196 ANATOMY AND PHYSIOLOGY

of the coral, and slightly twisted together like a rope.
Bark fleshy, granular, strengthened with short cylindrical
spicula. Polypiferous cells scattered, rather produced,
wart-like, with a flat radiated tip." (' Proceedings of the
Zoological Society of London ' for 1857, page 279.) This
description applies only to the singular cloacal appendage
to the sponge from amidst which it springs, the structure
of the body of the animal being evidently considered by the
author as an extraneous mass. The basal sponge is un-
doubtedly a portion of the animal to which the part de-
scribed by Dr. Gray belongs, the spicula of the elongated
cloacal portion being also abundant in the basal mass of
sponge ; and the basal mass of the specimen described by
Dr. Gray is identical in its structural character with that of
the specimen of Hyalonema mirabifis in the Bristol Museum.
It becomes necessary therefore to remodel the generic cha-
racters so as to embrace the leading distinctive structures
of the skeleton of the animal, and I propose the following
form of description :

Skeleton an indefinite network of siliceous spicula, composed
of separated elongated fasciculi, reposing on continuous
membranes, having the middle of the sponge perforated
vertically by an extended spiral fasciculus of single,
elongated, and very large spicula, forming the axial
skeleton of a columnar cloacal system.

Type, Hyalonema mirabiUs, Gray.

The construction of the skeleton of the mass of the
sponge is intermediate between that of Halichondria pa-
nicea and Hymeniacidon caruncnla, the respective types of
those genera, The network of fasciculated spicula appears
never to be definite and continuous as in the former, nor
are the skeleton spicula in a dispersed condition on the con-
tinuous membranes as in the latter, but are gathered into
elongated fasciculi which cross each other in the same plane
in every imaginable direction, but without ever appearing
to anastomose. The fasciculi vary exceedingly in the

OF THE SPONGIAD^E. 197

number of spicula of which their diameter is formed, some-
times consisting of two or three spicula only, and at other
times of more than it is possible to count. They often
divide, the branches passing in different directions, but they
never reunite or anastomose with other fasciculi. A portion
of this network of spicula is represented by Fig. 375, Plate
XXXV. The columnar axis of the cloacal system consists
of one large spiral fasciculus of spicula, each of which
extends from the base or very near that part of the sponge,
to near or quite to the apex of the column, the direction of
the spiral being from right to left. Fig. 374, Plate
XXXV, represents a portion of the great cloacal column,
exhibiting part of the spiral axial fasciculus surrounded by
the remains of its dermal coat, with numerous oscula pro-
jecting from its surface, copied from ' Zoological Proceed-
ings ' for 1857.

There is a close approximate alliance to this form of the
cloacal appendage of Hyalonema in the corresponding organs
of the British genus Ciocalypta, Bowerbank.

ISODICTYA, Bowerbank.

SPONGIA, Montagu.
HALICHONDRIA, Fleming.
HALICHONDRIA, Johnston.

Skeleton without fibre ; composed of a symmetrical network
of spicula ; the primary lines of the skeleton passing
from the base or centre to the surface, and the
secondary lines disposed at about right angles to the

primary ones. Propagation bv internal, membra-

• i i

naceous, aspiculous gemmules.

Types, Isodictya palmata and Normani, Bowerbank.

This genus, in the structure and arrangement of its
skeleton, is intermediate between Halichondria and Chalina,
as defined in the present work. Like the former, the
spicula of the network composing the skeleton are merely
cemented together, not inclosed within a regular horny

193 ANATOMY AND PHYSIOLOGY

fibre ; but the disposition of the network is not entirely
irregular, but like that of the latter genus, more or less
composed of a primary series of lines radiating from the
axis or base of the sponge, and of secondary series connect-
ing the primary ones at about right angles to them ; in fact
simulating very closely the arrangement of the skeleton of
Chalina oculata, but without the keratose fibre surrounding
the spicula of the skeleton in that sponge.

In some of the species of this genus the symmetrical
arrangement of the lines of the skeleton is distinct only near
the surface of the sponge, while in the more deeply seated
parts, the irregular characters of a Halichondria is simu-
lated. In determining the species of this genus, the
sponge requires to be carefully examined by sections at
right angles to the surface, where the distinctive character
rarely fails to be readily detected. On the contrary, in
Halichondria panicea, the type of that genus, I have never
succeeded in finding such a linear arrangement of the
skeleton as marks that of Isodictya. In a hasty examina-
tion a single linear series of spicula will therefore often
prove an excellent guide to the discrimination of this

genus.

In most of the species with which I am acquainted there
is a generally prevailing character of fragility ; the primary
lines being composed of very few spicula, while the secon-
dary ones, are most frequently unispicular. Most of the
species are thin, coating or encrusting sponges, and rarely
appear to rise in tuberous masses, as the numerous species
of Halichondria are in the habit of doing.

Isodictya infundibuUformis is perhaps the most perfect
type of the genus, as in it we have the primary and secondary
lines of the skeleton distinctly separated by the difference
in the form of their spicula. In some species of the genus,
as in /. simulo, the cementing keratode of the skeleton is
so abundant in some parts as to cause it to simulate very
closely the structure of a Chalina, but the irregularity and
compressed form of this pseudo-fibre is readily to be dis-
tinguished from true keratose fibre by a careful observer.
In other species, as in /. mammeata, the sarcode surrounding

OF THE SPONGIAD^E. 199

the skeleton is so abundant as to cause it to simulate a
delicate form of Chalina, but on immersion in Canada
balsam the fibre-like form disappears, the sarcode con-
tracting into a mere granulated coating, and the skeleton
assumes the normal appearance of Isodictya. Tig. 370,
Plate XXXVI, represents a section at right angles to the
surface from Isodictya Normani, exhibiting the regular and
nearly rectangular structure of the network of the skeleton,
X 108 linear.

SPONGILLA, Linnteus, Lamarck, and Johnston.

HALICHONDRIA, Fleming.

The structural peculiarities of the skeleton of Spongitta
are the same as those of Isodictya, and if there had not
existed a striking distinctive difference in their reproductive
organs the two genera must have been united. Under
these circumstances I propose the following as the characters
of the genus Spongilla.

Skeleton without fibre, composed of a symmetrical network
of spicula ; the primary lines of the skeleton passing
from the base or centre to the surface, and the
secondary lines disposed at about right angles to the
primary ones. Reproductive organs, ovaries, coriaceous
and abundantly spiculous.

Type, SpongillajliwiatiliS) Linnaeus.

All the species are inhabitants of fresh water. As an
illustration of the form of the skeleton in this genus, see
the figure of that of Isodictya Normani, Fig. 376, Plate
XXXVI.

In some species from the River Amazon, the skeleton
fibre is so abundantly spiculous as to cause it closely to
simulate that of a Desmacidon ; but a careful observation
of the more slender portions of the skeleton will dispel this
illusion.

200 ANATOMY AND PHYSIOLOGY

Suborder IV. Spiculo-fibrous skeletons. Regularly fibrous.
Fibres filled with spicula.

Desmacidon.

Raphynis.

The spiculo-fibrous skeletons differ from the fibro-spicular
ones in this respect. In the first the form and proportions
of the fibre are dependent on the greater or the less de-
velopment of spicula, and the keratode serves only as a
cementing and coating material. In the latter the keratode
is the primary agent in the formation of the fibre, and the
spicula the secondary or auxiliary agent only.

DESMACIDON, TSowerbank.

HALICHONDBIA, Johnston.

Skeleton fibrous, irregularly reticulated. Fibres composed
entirely of spicula arranged in accordance with the
axis of the fibre, cemented together and thinly coated
with keratode.

Type, Desmacidon fruticosa, Bowerbank.

The structure of the skeleton fibre in this genus readily
distinguishes it from all others. The form and size of the
tissue is entirely dependent on the greater or less quantity
of spicula present ; the keratode serving only as a cementing
and coating material. Halichondria wgagropila andfntti-
cosa, Johnston, are the only two British species of the genus
known. Fig. 264, Plate XIII, represents a fibre from the
skeleton of Halichondria (eyagropila, Johnston, illustrating
the structure of multispiculated keratose fibre, X 108.

OF THE SPONGIAD^E. 201

RAPHYRUS, Bowerbank.

Skeleton fibrous, but not horny. Fibre composed of a
dense mass of siliceous spicula mixed together without
order.

The structure of this genus is singular. The fibre in
the only species with which I am acquainted, Raphyrus
Griffithsii, is comparatively very coarse, frequently attaining
the size of a line in diameter near the anastomosing parts,
or expanding into a broad plate-like form. The spicula
composing it are closely thrown together without any
approach to the longitudinal disposition which prevails in
the skeleton of Desmacidon. The same absence of definite
arrangement obtains in the interstitial membranes, which
have precisely the mode of structure which characterises
the genus Hymeniacidon, which has " spicula without
order, imbedded in irregularly disposed membranous
structure."

Fig. 205, Plate XIII, represents a longitudinal section
of a small fibre of the skeleton of Raphi/rns Griffithsii,

L «/ t*/

Bowerbank, showing the irregular disposition of the spicula
within it, X 90 linear.

Suborder V. Compound reticulate skeletons, having the
primary reticulations fibro-spiculate, and the interstices
filled with a secondary spiculo-reticulate skeleton.

Diplodemia, Bowerbank.

This Order forms a connecting structural link between
the Orders Silicea and Keratosa. The structure, of the
keratose fibre would indicate its place to be in the third
suborder of the latter, but the presence of the Halichon-
droid secondary skeleton in such force, in conjunction with
the irregular spiculated structure of the kerato-fibrous
primary skeleton, has induced me to place it among the

202 ANATOMY AND PHYSIOLOGY

Silicea. For more minute information regarding its struc-
tural peculiarities, I must refer my readers to the following
description of the generic characters of Diplodemia.

DIPLODEMIA, Bowerbank.

Skeleton fibrous. Fibres keratose, hetro-spiculous ; com-
bined with a secondary skeleton of irregular network
of spicula ; rete unispiculate, rarely bispiculate. Ova-
ries membranous and spiculous.

Type, Diplodemia vesicula, Bowerbank.

The fibres in the skeleton of the only known species in
this genus are very remarkable. They are smooth and
cylindrical, having an axial line of, generally speaking,
single spicula united at their points, running throughout
the whole length of the fibre. But when it is of more than
ordinary diameter, there are frequently other spicula at
intervals imbedded in the fibre parallel to the axial series.
Throughout the whole length of the fibres, at short inter-
vals, there are similar spicula to the axial ones, imbedded
at right angles to the axis of the fibre, frequently project-
ing from the surface for half, or more than half their length.
Some of these projecting spicula originate small lateral
branches of the keratose skeleton, but by far the greater
portion of them are the connecting points of the keratose
fibres and the reticulo-spiculate secondary skeleton ; the
former being thus completely imbedded amidst the latter.

The structure of the ovaria in this genus is also peculiar
to it. The wall is very thin, and appears to consist of a
single membrane profusely furnished with spicula which
cross each other in every direction, and occasionally appear
to assume a somewhat fasciculated arrangement. They
are not uniform in shape, some being regularly oval, while
others are more or less ovoid.

But one species of this singular genus is known, D.
vesicula, Bowerbank, from deep water at Shetland. Fig.

OF THE SPONGIAD^E. 203

273, Plate XIV, represents a single hetro-spiculous fibre
of the skeleton, X 175 linear. Fig. 377, Plate XXXVI, a
portion of the fibrous skeleton with the imi-spiculate
secondary skeleton, X 108 linear; and Fig. 234, Plate
XXIII, a perfect ovarium of D. vesiculata, Bowerbank, and
a portion of a second one showing the interior and the
thickness of its walls in its natural state, X 83 linear.

Suborder VI. Solid siliceo-fibrous skeletons. Skeletons
reticulate. Fibres composed of concentric layers of
solid silex, without a central canal. Reticulations
unsymmetrical.

Dactyl ocalyx, Stutchbury (Iphiteon, French Museum).

The structure and mode of growth in this suborder of
siliceo-fibrous sponges appears to be precisely the same as
that of the kerato-fibrous sponges of the first suborder of
the third order Keratosa.

Dactylocalyae pumicea, Stutchbury, was described in the
' Proceedings of the Zoological Society,' part 9, 1841, p. 86,
October 26, 1841. The author describes it thus : " Sponge
fixed, siliceous ; incurrent canals uniform in size ; excurrent
canals large, forming deep sinuosities on the outer surface,
radiating from the root to the outer circumference."

The sponge was received by the Bristol Museum from
Dr. Cutting of Barbadoes.

The genus Dactylocalyx was established by Mr. Stutch-
bury to designate this fine siliceo-fibrons sponge. Half of
the type specimen is in the Museum at Bristol, and the
remaining portion in the possession of Dr. J. E. Gray of
the British Museum. A1 though the sponge was designated
Dactylocalyx pumicea, no generic characters were given. I
propose therefore to characterise it as follows :

204 ANATOMY AND PHYSIOLOGY

DACTYLOCALYX.

Skeleton siliceo-fibrous. Fibres solid, cylindrical. Reti-

' v

dilations unsymnietrical.
Type, DactylocalyaB pumicea, Stutchbury.

Fig. 274, Plate XV, represents the smooth variety of
fibre, with young fibres pullulating from the adult ones
at («). From the skeleton of McAndrewsia azoica, Gray,
X 175 linear.

Fig. 275, represents a portion of tuberculated siliceous
fibre from the skeleton of D. pumicea, Stutchbury, X 108
linear.

Fig. 276, exhibits very prominently tuberculated fibre
from D. Prattii, Bowerbank, MS.

Fig. 340, Plate XXV, represents a small portion of the
skeleton of Ipkiteon panicea in the Museum of the Jardin
des Plantes, Paris, with gemmules in situ, X 183
(Dadylocalyx, Stutchbury) .

Fig. 34 1 , a gemmule detatched from Iphiteon panicea,
X 666 linear.

Suborder VII. Canaliculated siliceo-fibrous skeletons.
Skeletons reticulate, symmetrical. Fibres composed
of concentric layers of solid silex, with a continuous
central canal.

Type, Farrea occa, Bowerbank, MS.

I have seen in the organic remains from deep sea sound-
ings several varieties of fragments of siliceous fibres with
simple central canals, having every appearance of being
from unknown species of siliceo-fibrous sponges ; but the
only satisfactory specimen of this genus of sponges is the
one at the base of Dr. Arthur Farre's specimen of Euplec-
tella cucumer, Owen, described in the ' Transactions of

OP THE SPONGIADyE. 205

the Linnean Society of London,' vol. xxii, p. 117, plate
xxi.

The fibres in Farrea occa are rather coarse, abundantly
tubercnlated, and the mode of reticulation is rectangular.
Their construction is exactly like those of Verongia, the
type of the fourth suborder of the third order, Keratosa.
Pig. 277, Plate XV, represents one of the simple fistulose
spiculated fibres from the skeleton of Farrea occa, Bower-
bank, MS., X 108 linear.

Order III. KERATOSA.

Suborder I. Solid non-spiculate kerato-fibrous skeletons.

The greater number of the sponges of commerce belong
to this suborder. How many species are comprised under
the designation of " the sponges of commerce " it is very
difficult to decide, as we rarely obtain them in their
natural condition, but it is certain, from their well- washed
skeletons, that their number is considerable, and that at
least two distinct genera occur among them. If we
assume that the well-known cup-shaped sponge, usually
sold as the best Turkey sponge, is the one entitled to the
designation of Spoiigia officinalis, we shall then have the
type of the first suborder of the third order Keratosa dis-
tinguished by the above characters. There are two genera
belonging to this suborder ; the first of these is Spongia,
Linna3iis. Its character is as follows :

SPONGIA, Linnaus.

Skeleton kerato-fibrous. Fibre solid, cylindrical, aspiculous.
Rete unsymmetrical.

Type, Spongia officinalis, Linnaeus.

The number of species of Bpongia appear to be very
considerable, and in all of them the irregular meandering

206 ANATOMY AND PHYSIOLOGY

character of the skeleton fibre readily serves to distinguish
them. Fig. 379, Plate XXXVII, exhibits the irregularity
of the disposition of the keratose fibres from one of the
best Turkey sponges of commerce, X 50 linear, and Fig.
261, Plate XIII, a fibre from a similar description of sponge,
from a specimen preserved in spirit in the condition in
which it came from the sea, X 175 linear.

The second genus is founded on the specimen described
by Sowerby in the ' British Miscellany,' p. 87, plate xlviii,
and named by him Spongia pulcheJIa. I fortunately have
this specimen, and on carefully examining it I find it to
possess all the characters of the genus Spongia, excepting
that the reticulations of the skeleton are very symmetrical,
and this is so important a structural difference that I have
thought it advisable to constitute it the type of a new genus
the characters of which are as follows :

SPONGIONELLA, Bowerbank.

SPONGIA, Sowerby and Johnston.

Skeleton kerato-fibrous. Fibres solid, cylindrical, aspicu-
lous. Rete symmetrical ; primary fibres radiating
from the base to the apex. Secondary fibres disposed
at nearly right angles to the primary ones.

Type, Spongionella pulcheUa, Bowerbank.

Fig. 380, Plate XXXVII, represents a section at right
angles to the surface from the type specimen Spongia pul-
chella, Sowerby, showing the nearly regular rectangular
mode of disposition of the primary and secondary fibres of
the skeleton, X 50 linear.

Suborder II. Solid, semispiculate, kerato-fibrous skele-
tons.

The sponges of this suborder closely resemble in general
appearance those of the genus Spongia, but they differ very

OF THE SPONGIAD.E. 207

considerably in the structural characters of their skeletons,
which consist of a somewhat irregular radiation of primary
fibres from the base towards the apex of the sponge, with
an unsymmetrical series of secondary fibres emanating
from and connecting together the series of primary ones.

The primary fibres are compressed and broad in their
form, frequently three or four times the width of the
diameter of the surrounding cylindrical secondary ones.
But their most striking character is their possessing a con-
siderable number of siliceous spicula, which are irregularly
imbedded in their centres ; sometimes the series of spicula
within the fibre consists of but one or two beside each
other, and at other times they are numerous and very
irregularly disposed. This central series of spicula appears
to exist only in the primary fibres, and I have never been
able to detect the slightest indication of their presence in
any of the secondary series. I first described these
structural peculiarities in a paper read before the Micro-
scopical Society of London, January 27, 1841, and it is
published in vol. i, p. 32, plate iii of their ' Transactions.'

I have met with numerous instances of the occurrence of
this structural arrangement of the skeleton in sponges from
Australia and the Mediterranean, but their well- washed
condition has left them with but very few capabilities for
specific distinction.

I propose to adopt De Blainville's name, Halispongia,
to designate this genus, the characters of which are as
follows :

HALISPONGIA, De Blainville.

Skeleton kerato-fibrous. Fibres solid ; primary fibres com-
pressed, containing an irregularly disposed series of
spicula. Secondary series of fibres unsymmetrical,
cylindrical, without spicula.
Fig. 278, Plate XXXVI, represents one of the large

primary keratose fibres containing siliceous spicula, and the

rregular system of small aspiculous keratose fibres, X 175

inear.

208 ANATOMY AND PHYSIOLOGY

Suborder III. Solid, entirely spiculate, kerato-fibrous
skeletons.

CHALINA, Grant.

Skeleton fibrous. Fibres keratose, solid, cylindrical, and
interspiculate. Rete symmetrical; primary lines ra-
diating from the basal or axial parts of the sponge to
the distal portions. Secondary lines of fibre at about
right angles to the primary ones.

Type, Chalina oculata, Bowerbank.

The type of this genus, Halickondria oculata, Johnston,
differs so materially in the structure of its skeleton from
that of the type of Halichondria, H. panicea, Johnston,
that it becomes necessary that a distinct genus should be
established to receive it and other closely allied British
species. The skeleton consists of a solid, cylindrical, kera-
tose fibre, enclosing a single or compound series of spicula,
imbedded at or near its centre, and disposed in lines parallel
to its axis ; thus forming a structural group intermediate
between that of Halichondria panicea and Spongia offi-
cinalis.

In the sponges of this genus the spicula are decidedly
subservient to the fibre, which is always cylindrical, and
generally very uniform in its diameter throughout the whole
of a section made at right angles to its surface ; while in
the nearly allied genus, Isodictya, the reverse is the case,
the spicula being the essential basis of the skeleton, while
the surrounding keratode, although often abundant, is still
only the subservient cementing medium of the skeleton,
and never assumes the decidedly cylindrical form of that of
the fibre of Clialina.

In the c Edinburgh Encyclopaedia,' vol. xviii, p. 844,
Dr. Grant proposed the name Halina to represent those
species which were designated Halicliondria by Dr. Fleming,
and subsequently by Dr. Johnston, in his ' History of

OF THE SPONGIAD^E. 209

British Sponges,' but as I have already proposed to restrict
the term Halickondria to those species which agree in
structure with the original type of that genus, H. panicea,
Johnston, it becomes necessary to select other names to
represent the sponges which differ essentially in their struc-
ture from that type, and I therefore propose to adopt
Dr. Grant's genus Ghalina, designated in his ' Tabular View
of the Animal Kingdom,' published in 1861, to represent
that portion of them which agree in structure with the well-
known species described in the ' History of the British
Sponges' as HdlicJtondria oculata. Fig. 262, Plate XIII,
represents the fibres of Chalina oculata, Bowerbank (Hali-
chondria, Johnston), illustrating the structure of spiculated
keratose fibre, and Fig. 263 exhibits the mode of growth
of the fibre in Chalina Montagui, Bowerbank, (a] the
apical spiculum of the growing fibre.

Suborder IV. Simple fistulo-kerato-fibrous skeletons.

The type of this suborder is Lamarck's Spongia fistulosa.
The anatomical structure and the general habits of the
sponges of this description are so widely different from the
true Spongias, that I was induced to establish them as a sepa-
rate genus, and I accordingly designated and described them
as such in the ' Annals and Magazine of Natural History'
for December, 1845, vol. xvi, p. 400, plate xiii, fig. 7. It is
unnecessary to enter here into a detailed account of these
tissues, as I have described the peculiarities of the struc-
ture of the simple fistulo-keratose fibrous skeletons at length
in describing the nature and structure of the fibrous tissues
of Spongiadae. Fig. 266, Plate XIII, represents the simple
keratose fibre from Spongiafistularis, Lamarck, X 108 linear.

The genus may be characterised as follows :

VERONGIA, Bowerbank.

SPONGIA, Lamarck.

Skeleton kerato-fibrous. Fibres cylindrical, continuously
fistulose, aspiculotis. Rete imsymmetrical.

14

210 ANATOMY AND PHYSIOLOGY

Type, Verongia fistulosa, Bowerbank.

Suborder V. Compound fistulo-fibrous skeletons.

This suborder is founded on the peculiarities in the
structure of the skeleton fibre of a sponge described by me
in the ' Annals and Magazine of Natural History' for
December, 1845, vol. xvi, p. 405, plate xiii, figs. 1, 2,
and also in the account I have given of the fibrous structure
of the Spongiadce in this volume. Fig. 268, Plate XIV,
represents one of the fibres of the skeleton, X 100 linear,
with minute tubular fibres (a) which traverse the central
cavity of the large fibres. Fig. 267, Plate XIII, repre-
sents a portion of one of the skeleton fibres, exhibiting the
secondary canals radiating from the primary ones, X 300
linear.

The genus AuHslda is the only one in which compound
fistulo-keratose fibres have been found, and it may be thus
characterised :

AULISKIA, Bowerbank.

Skeleton kerato-fibrous. Fibres aspiculous, cylindrical,
continuously fistulose, primary fistulae having minute
csecoid canals radiating from them in every direction.
Rete unsymmetrical.

Suborder VI. Regular, semi-areno-fibrous skeletons.

The sponges of this suborder have the faculty of appro-
priating extraneous matter, such as grains of sand or the
spicula of other sponges, which become imbedded in the
centre of the cylindrical fibres of their skeletons. The
fibres in these cases are regular and cylindrical, and the
space between their surfaces and the central line of extra-
neous matter is frequently one fourth or one third of their
own diameter. The central axis of extraneous matters

OF THE SPONGIAD^!. 211

usually consists of a series of single grains, but occasionally
we find two or three compressed together. In some genera
belonging to this suborder the arenation of the fibres is
confined to the primary or radial ones, and the secondary
system of fibres are destitute of extraneous matters. In
other genera they occur occasionally in the secondary
system as well as in the primary one. In Stematumenia
the primary fibres are frequently somewhat compressed,
and are abundantly arenated. The smaller or secondary
series of fibres are usually cylindrical, and most frequently
without either grains of sand or spicula. Several of the
common Bahama sponges of commerce belong to this sub-
order, but the best type is the genus Stematumenia,
described by me in the ' Annals and Magazine of Natural
History3 for December, 1845, vol. xvi, p. 40G, plate xiv,
figs. 1, 2. The genus may be characterised as follows :

STEMATUMENIA, Bowerbank.

Skeleton. Primary fibres solid, more or less compressed,
containing a central axial line of spicula and grains of
extraneous matters. Interstitial structures abundantly
fibro-membranous.

Fig. 256, Plate XII, represents the fibro-membranous
tissue from the dermal membrane of a species of Stematu-
mema. The fibres are disposed without order, X 1 83
linear ; and Fig. 381, Plate XXXVII, a portion of a Stema-
tumenia exhibiting the skeleton fibres with the axial line of
sand and other extraneous matters, and the fibro-mem-
branous tissue in situ, X 175 linear.

Suborder VII. Irregularly and entirely areno-fibrous
skeletons.

Types, Dijsidea fragitis, Johnston.
Dysidea Kirkii, Bowerbank.

The peculiarity of this suborder is that the fibre of the

212 ANATOMY AND PHYSIOLOGY

skeleton is a full and complete but elongate aggregation of
particles of sand, each separately coated by keratode,
forming a series of stout anastomosing fibres, consisting of
innumerable extraneous molecules encased by a thin coat
of keratode.

In Dysidea Kirkii, an Australian species, both the pri-
mary and secondary fibres of the skeleton are comparatively
large, frequently exceeding half a line in diameter. In our
British species, Dysidea fragilis, Johnston, the primary
fibres are often as abundantly arenated as those of the
Australian species, while the secondary ones are only par-
tially filled with extraneous matter, and in this condition
they are frequently more or less tubular. The structure
and peculiarities of the above-named two species are de-
scribed in detail in vol. i, p. 63, plate vi, of the ' Transac-
tions of the Microscopical Society of London.' Tig. 270,
Plate XIV, represents a portion of one of the skeleton fibres
of Dysidea frag His, Johnston, exceedingly full of sand,
X 108 linear. Fig. 272 exhibits the mode in which a
fibre takes up and envelopes a particle of sand, X 108
linear ; and Fig. 271 represents a small piece of the sponge
in its natural state, X 108 linear.

ON THE DISCRIMINATION OF THE SPECIES OF THE

SPONGIAD.ZE.

One of the reasons why so little progress has been made
in our knowledge of the Spongiadae, is that the generic and
specific characters that are visible to the unassisted eye,
such as form and colour, are in this class of animals
remarkably uncertain and delusive, while all those that are
definite and constant require not only a high degree of
microscopical power to make them visible, but frequently
also a peculiar mode of treatment to render them apparent
even beneath the microscope. Thus it is with many of the
finer forms of stellate spicula, which are very characteristic
in Tethea, Geodia, Spongilla, and other genera. When we
search for them bv the dissolution of the tissues in nitric

OF THE SPONGIAD.E. 213

acid, they are so minute that by far the greater part of
them, even with the most careful treatment, are washed
away ; and when the tissues in which they are imbedded
are examined in water, they are totally invisible in the sar-
code in which they are immersed; and it is only when
small portions of such tissues are mounted in Canada
balsam that they become distinctly visible in situ. The
correct classification, therefore, as well as the anatomy and
physiology, is really a microscopical science ; and it is only
since we have possessed instruments of high defining and
penetrating powers, that we have been properly prepared
for the investigation of the structures and the correct deter-
mination of the generic and specific characters of these
interesting and curiously constructed animals. A careful
and patient examination of their component parts is there-
fore absolutely necessary for the determination of species,
and the whole of the structures present should be noted,
and their peculiarities accurately described.

In the first place we will consider what are the parts of
the organization of the Spongiadas that may be used for the
purposes of specific distinction; and secondly, endeavour
to form an estimate of their relative values.

The parts of the sponge to be thus employed are as
folio WS:_1. The Spicula. 2. The Oscula. 3. The Pores.
4. The Dermal Membrane. 5. The Skeleton. 6. The
Interstitial Membranes. 7-. The Intermarginal Cavities.
8. The Interstitial Canals and Cavities. 10. Sarcode.
11. Ovaria and the Gemmules.

1. The Sjricula.

The spicula in the descriptions of the Spongiadae are of
about the same relative value that the leaves of plants are
in botanical descriptions. I have shown in the preceding
portion of this work, that they are exceedingly various in
form in the different species ; and even when of the same
shape in two different sponges, as represented in Pigs. 1, 2,
Plate I, their relative proportions are frequently so distinctly

214 ANATOMY AND PHYSIOLOGY

different, as to render them almost as valuable as if they
varied from each other in form. Wherever therefore spicula
form a component part of the skeleton, they become a leading
character in the discrimination of species. But it is not only
those of the skeleton that are thus available, as in different
sponges they vary in shape and size in each separate organ
belonging to the animal ; and in some cases we find as
many as five or six distinct descriptions of spicula, each of
which affords an invariable and excellent character. Thus, in
the descriptions of sponges, it is not only the forms and relative
proportions of the skeleton spicula which have to be taken
into consideration, but those also of the dermal and inter-
stitial membranes (the external and internal defensive ones),
those of the sarcode, and of the ovaries and gemmules.
Those of the latter three organs named frequently afford the
most determinative characters. Thus in the genus Sjjo?i-
yilla but one form of spiculum, the acerate, prevails in the
skeletons of nearly all the known species ; but the minute
and beautiful spicula of the ovaria varies in form and size in
each species in a perfectly unmistakeable manner, so that
if the organs of reproduction be present, which is most
frequently the case, the species may be readily recognised
from their spicula only. But in other cases, and even in
the same genus in the absence of the ovaria, the differences
between two nearly allied species are equally well deter-
mined by the spicula of the dermal and interstitial mem-
branes. Thus in our two species of British Sjjongilla, S.
ftuviatilis has no tension spicula different from those of the
skeleton, while in 8. lacustris we find the fusiformi- acerate
entirely-spined spiculum, represented by Fig. 90, Plate IV,
in abundance. So likewise in two species of Tethea, T.
cranium from Shetland, and T. simillima, Bowerbank, MS.,
from the Antarctic regions, the only well- determined
difference that exists is, that the sarcode of the former is
profusely furnished with exceedingly minute sigmoid
spicula, while that of the latter is entirely destitute of them.
It will therefore be seen that these exceedingly minute
organs frequently afford the most valuable and certain
means of discriminating species. But although so minute,

OF THE SPONGIAD^l. 215

we must not imagine that it is very difficult to obtain these
characteristic evidences ; for. as I shall show more at length

•

hereafter, it requires but the dissolution of a small piece of
the sponge in hot nitric acid to at once furnish us with a
general view of the whole of the spicular contents of the
sponge under examination ; so that, to one who has become
familiarised with the general characteristics of the forms and
sizes of the different classes of spicula peculiar to each organ
of the sponge, such a preliminary observation at once indi-
cates the nature and especial seat of the principal specific
characters of the subject under examination.

In some sponges the relative variation in size of the adult
skeleton spicula is greater than in others ; but this vari-
ation, although sometimes a substantial character, must not
be always assumed to be correct, as in young sponges with
simple forms of skeleton it is very difficult to discriminate
between the young and only partially developed spicula
and the adult ones. Thus in a young specimen of Spon-
gilla fluviatilis, I found in the same field of view one
spiculum perfectly well proportioned, which measured
g^th of an inch in length and t^th of an inch in diameter ;
another ^th of an inch in length and ^th of an inch in
diameter ; the length and diameter of an average-sized
spiculum of the species in a fully developed condition being,
length ^th of an inch, and diameter ^th of an inch.

Abnormal or immature forms must not be mistaken for
fully developed and normal ones, as we find in some of the
more complicated forms of spicula that the development of
form is quite as progressive as that of size ; as instanced in
Figs. 73, 74, 75, and 76, Plate III, which represent the
progressive stages of development of the spinulo-recurvo-
quaternate form of spiculum, and also in Figs. 144, 145,
146, and 147, Plate VI, representing the progressive de-
velopment of the dentato-palmate inequi-anchorate spiculum.

2. The Oscula.

The oscula frequently afford good specific characters.
Their peculiarities are, first, those of position ; and secondly,

216 ANATOMY AND PHYSIOLOGY

those of form. Thus it should always be noted whether
they are dispersed or congregated ; whether disposed on
the exterior surface, or on the parietes of internal cloacae.
In form they are either simple orifices, or they assume a
tubular shape to a greater or a less degree, and sometimes
they are bounded by a slightly elevated marginal ring. All
these characters are subject to a considerable amount of
variation, which are sometimes dependent on peculiarities
of locality, and at others on age or the amount of their
development; but a comparison of several specimens of
the same species will generally lead the observer to a correct
conclusion regarding their normal characters.

In some species these organs are always more or less
open ; in others, especially littoral ones, they are entirely
closed during exposure to the atmosphere, or while in a
state of repose, during which condition they are frequently
completely inconspicuous.

3. The Pores.

The pores afford but very few available characters. They
are either dispersed or congregated ; very rarely in the
latter state. They are also either conspicuous or incon-
spicuous ; that is, in the former condition their presence,
and the areas within which the groups of them are situated,
may be readily detected by the aid of a hand-lens, or in the
latter case they are perfectly undistinguishable without high
microscopic power.

4. The Dermal Membrane.

The dermal membrane affords many important specific
characters. In the greater number of the Spongiadae it is
a simple pellucid membrane, which invests the whole of the
mass of the sponge ; but in other cases it is of much more
complex structure, sometimes furnished abundantly with
primitive fibrous tissue, or a network of spicula or kerato-
fibrous tissue for its especial support ; and in the areas of
such network there are frequently tension spicula differing

OE THE SPONGIAD.E. 217

in construction from those of the skeleton, and its interior
surface is often supplied with anchorate retentive spicula of
various forms. In its sarcodous lining there are occasionally
an infinite number of stellate or sphero-stellate spicula to
protect it from the ravages of minute enemies, and its
surface is also often penetrated by large or small defensive
spicula. Occasionally its external surface is profusely
supplied with elongo-stellate defensive spicula. It has also
frequently a thick stratum of cellular structure of various
colours.

These peculiarities of structure have no generic value.
They are essentially specific differences ; and it is rarely the
case that any two species, even in an extensive genus, are
found to agree in the possession of the number, form, or mode
of disposition of these peculiarities of the dermal tissues.
They form therefore a constant and highly valuable series of
characters, and claim the especial attention of the student
in either the recognition or description of an unknown
species.

5. The Skeleton.

Although the material, mode of structure, and arrange-
ment of the skeleton is more especially devoted to the
formation of the orders and suborders, it still presents us
with a sufficient number of minor peculiarities to render it
a source of valuable specific characters. Thus, as I have
already shown in treating of the relative value of the
spicula for the distinction of species, the difference in their
size affords a good character. The closer or more diffuse
mode of their arrangement modifies to a great extent the
form and size of the areas in spiculo-reticulated skeletons,
and their habitually greater or less number in the thread of
the reticulations produces a distinctly different aspect in
the skeletons of two otherwise closely allied species. The
presence or absence of defensive spicula, the mode of arma-
ture, and the forms of the defensive and other auxiliary
spicula also afford a very extensive and valuable series of
specific characters. In the kerato- and siliceo-fibrous

218 ANATOMY AND PHYSIOLOGY

sponges there are peculiarities of a similar description, such
as the presence of a re ticnlo- fibrous sheath, as represented
by Figs. 279, 280, Plate XVI, or the possession of
spines or tubercles of various forms, as represented in
Figs. 275, 276, Plate XV, or of extraordinary modifica-
tions for prehension, as in the cidarate siliceo-fibrous
skeleton, represented also in the same Plate, fig. 278.
These and other similar structural peculiarities afford a
series of characters which are usually of a permanent and
very striking description.

6. The Interstitial Membranes,

The peculiarities of the interstitial membranes consist
principally in the shape and proportions of their tension
spicula, or of the forms and varieties of structure, and
mode of disposition of the retentive spicula. The latter
class of organs especially present a very extensive series of
striking characters that are essentially specific. In the
genera Hatichondria, Isodictya, Hymeniatidon and others
containing numerous species, often very closely resembling
each other in all the principal structural characters, they
frequently, from the strongly marked peculiarities in their
form and proportions, present most valuable and decisive
specific characters, as in Figs. 255, 256, 257, 258, and
259, Plate XII.

In Alcyoncettum and other genera the interstitial mem-
branes are strengthened and supported by layers of pri-
mitive fibrous tissue, arranged in parallel lines, and in
Stematumenia the same fibres abound, but they are not
disposed in the same symmetrical manner; and in some
sponges cellular structures are present in considerable
quantities. These tissues are all more or less valuable as
aids in specific distinction.

7. The Intermarginal Cavities.

The intermarginal cavities in the greater portion of the
Spongiadee are so indefinite in their form as to render but

OF THE SPONGIADjE. 219

little service in the distinction of species ; but in Geodia,
Pachymatisma, and a few other genera their structure is
very much more regular, and their form, proportions, and
mode of disposition afford good characters. But although
of no extensive essential value themselves, their subsidiary
tern ate spicula present a great number of strongly marked
specific distinctions, arising not only from their varieties of
form and proportion, but also from their relative positions
in the dermal crusts of those genera where they most
abound ; and their modes of disposition and connection
with each other are also very characteristic.

8. The Interstitial Canals and Cavities.

These organs themselves present very few characters
that are of much service in specific descriptions, but their
subsidiary spicula are often very suggestive of the nature
and character of the species. Of this description are the
recurvo-ternate spicula in the interstitial cavities imme-
diately beneath the dermal crust of some species of Geodia,
and just without the dermal membrane of Tethea cranium ;
the remarkable groups of recurvo-quaternate spicula, repre-
sented by Fig. 292, Plate XVIII; the trenchant bihamate
spicula of Hymedesmia Johnsoni, Fig. 112, Plate V, and
Fig. 293, Plate XVIII ; and many other instances of
offensive or defensive spicula, either disposed in groups or
singly in these canals or cavities.

9. The Cloacal Cavities.

The cloacal cavities are especially valuable and charac-
teristic in the calcareous sponges. Their position, number,
extent, and form ; the number and position of their
excurrent orifices ; the mode in which those orifices are
armed and the nature of that armature, or the entire
absence of such defences ; the internal defensive spicula,
their varieties of form, and mode -of arrangement, — all

220 ANATOMY AND PHYSIOLOGY

these characters are highly effective and valuable as specific
descriptions. In other genera of sponges the cloacae afford
striking and very effective distinction, especially in Alcyon-
cdlum, Polymastia, Halyphysema, and Hyalonema. Among
the Keratosa it also prevails to a considerable extent, but
in the latter order it does not afford us the same wide
range of striking characters that exist so abundantly in the
cloacse of the order Calcarea.

10. The Sarcode.

The universal presence and similarity in structure of the
sarcode of the Spongiadae renders the range of its use as a
specific character very limited ; but the spicula imbedded
in its substance so abundantly in many species are so
various in form, and so strikingly distinct from each other,
as to afford a most valuable series of discriminative
characters.

The greater portion of these spicula are more or less
stellate in form. They vary in shape to a considerable
extent in each group, in consequence of incomplete or
complete development, and the number of the radii in the
stellate forms is in many cases very uncertain ; but although
this amount of variation exists in each of the separate
forms, there is always a limit to these differences, and a
normal character present which renders it by no means
difficult to decide to which class they belong. Independent
of the peculiar characters of their own form and modes of
radiation, their radii are frequently peculiarly and abun-
dantly spinous, and these secondary organs are equally as
constant and determinative in character as the primary radii.
The latter of these characters are frequently very minute,
and require the application of a high microscopic power to
render them available ; but they are in many cases so
decisively valuable, that they should never be neglected
when present. In truth, the spination of these and all
other forms of spicula are of considerable value as specific
characters, and their shape and direction are often indicative

OF THE SPONGIAD^E. 221

of the character and purpose of the spiculuin on which
they are based.

The range of the stellate spicula are very considerable.
They are found abundantly and constantly in Gcodia,
Pachymatisma, Tet/iea, Dactylocalyac, and Alcyoncelfam, and
in some species of Spongilla, Dictyocylindrus, and other
genera.

11. The Ovaria and Gemmules,

Where the ovaria exist they afford excellent descriptive
characters. Their construction is the same throughout the
whole of the known species of Geodia and Pachymatisma.
The varieties in their form, although not always easy of
description, are yet readily distinguishable by a practised
eye ; and the difference in the degree of stoutness of the
radiating spicula of which they are constructed, and the con-
sequent fineness or coarseness of the reticulations on their
surface, very often affords good discriminative characters.

In Spongilla, the varieties in their shape, and the
strikingly distinct forms of their component spicula, render
them exceedingly efficient for specific descriptions ; and
without them it would, in several instances among the
exotic species, be very difficult to find descriptive characters
to separate one species from another.

Excepting in Diplodemia, where the structural peculi-
arities of the ovarium are widely different from the preced-
ing instances, we know very little more of these organs ;
but there is good reason to believe, from certain forms of
spicula detected in the deep-sea soundings, the sources of
which are at present unknown, that other marine sponges
possess ovaria with which we are at present unacquainted.

The gemmules afford very efficient specific characters in
some species of Tethea ; but in the greater number of
Halichondroid genera, although frequently present in abun-
dance, they agree so closely in structure with each other as
to render them of very little use as specific characters.

We thus find that we possess eleven distinct varieties of

222 ANATOMY AND PHYSIOLOGY

organic specific characters, many of which are exceedingly
prolific in materials for descriptive purposes. A long
familiarity with them has assured me of their value, and of
their constancy in each species. However protean the
form and colour may be, the organic structures can always
be recognised with certainty, provided the specimen under
examination has been dried in the condition in which it
has been taken from the sea. To the organic characters
may be added the less definite and valuable ones of form
and mode of growth, which, although less to be depended
on than the organic ones, are frequently of service in con-
junction with them, as leading and suggestive in the first
stage of investigation.

A dependence on the specific characters to be derived
from form alone inevitably leads to erroneous conclusions.
Thus from trusting too implicitly to it in the descriptions
of his species, Dr. Johnston, in his ' History of British
Sponges/ has made two species out of one in the case of
Dysidea fragiliSi the thin coating form of this sponge being
also described as Halichondria areolata. Halichondria
incrustans has also been described a second time as Hal.
sabiirrata. An elongated form of Halichondria ficus has
also been again described as Hal. mrgultosa. The type-
specimen of Halichondria sevosa, Johnston, in the British
Museum proves to be merely a thin coating variety of
Halichondria panicea ; and the type-specimen of Montagu's
Spongia digitata in the possession of Professor Grant, Hali-
chondria cervicornis, Johnston, on being microscopically
examined, proved not to be a sponge but an alga.
Numerous other instances of error arising from a depend-
dence on form alone as a specific character might be cited,
but those I have given above are sufficient to prove the
ineligibility of so mutable a character unaccompanied by
organic structure.

Nearly the whole of this extensive series of specific cha-
racters have hitherto not been applied in the descriptions
of the SpongiadaB, excepting in my own manuscripts. This
omission has occurred, not from any doubt of their value,
but simply because they were unknown to naturalists. It

OF THE SPONGIAD^E. 223

now remains to be proved how they may be rendered
available in future descriptions of those animals. I cannot,
perhaps, better attain this end than by detailing the order
and mode of employing them in the description of species
contained in my own Manuscript ' History of the British
Sponges/ The following is the order in which these
characters have been taken for examination and descrip-
tion : —

1. Form. 2. Mode of Growth. 3. Surface. 4. Oscula.
5. Pores. 6. Dermis, and Dermal Membrane and its
Spicula. 7. Skeleton and its Spicula. 8. Connecting
Spicula. 9. Defensive Spicula, — external, internal. 10.
Spicula of the Membranes, — tension spicula, retentive
spicula. 11. Sarcode and its Spicula. 12. Ovaria and
Gemmules and their Spicula.

Colour.

Habitat.

Condition when examined.

This order of description, or any other that the student
may prefer, should always be adhered to, and no part of
the specimen under examination that is present, and which
affords specific characters, should be omitted in the descrip-
tion ; so that, when no mention is made of particular organs
or classes of spicula, it may be presumed that they are not
present in the sponge in course of description. A certain
portion of these characters are always available. Thus the
skeleton, incurrent canals or cells, the sarcodous system, the
dermal and interstitial membranes, the pores, and the oscula
are always present, while the excurrent canals or the cloaca
are occasionally absent. The intermarginal cavities, if
present, are not always distinguishable, and the external
and internal defensive organs are, either one or both of
them, frequently absent.

Specific characters should always be of a positive nature,
such as the presence and form of particular spicula or other
organs. It is a great mistake, in writing specific descrip-
tions, to make the differences between species to consist of
one or two striking essential characters only. Such a prac-
tice may answer tolerably well when there are but two or

224 ANATOMY AND PHYSIOLOGY

three species of a genus known ; but it frequently occurs
when new species are found, that they also have the most
striking essential characters of the previously known ones
equally strongly developed. Much confusion is thus likely
to occur from this paucity of description ; whereas, if the
whole of the essential characters of each species be carefully
investigated and accurately recorded when it is first charac-
terised, that description will most probably suffice perma-
nently to distinguish it as a species, however numerous the
subsequently discovered members of the genus may be.

Differential characters should never be intermingled with
essential ones in characterising the species. They should
be reserved for the amplified history ; and here they are of
much value, as they lead to the relative consideration of two
or more nearly allied species, and frequently assist the
student in their discrimination when the essential characters
are minute or somewhat obscure.

In the description of species the adjectives long, short,
stout, slender, &c., must always be understood as in com-
parison with the congenerous organs of the species under
consideration, and not as in relation to any fixed standard
of size.

In the description of a new species it should always be
stated whether the characters are given from a dried
specimen, or whether from one fresh from the sea, as it
frequently happens that many of the natural characters
become completely obliterated and sometimes reversed by
drying ; thus the surface smooth in the live state become
villous when dried. Inconspicuous oscula become con-
spicuous when contracted and dry, and conspicuous oscula
are often destroyed by desiccation, and so on with other
characters. It is therefore absolutely necessary that the
condition of the specimen should be stated along with its
description.

01' THE SPONG1AD.E. 225

On the Preservation and Examination of the Spongiadce.

The greater portion of specimens in natural history may
be readily examined and their species determined in the
field ; but this is rarely the case with the Spongiadse. It
becomes necessary therefore to preserve them in such a
manner as to effectually retain their natural characters for
examination at some future period. Small specimens may
be preserved in spirit of wine, but this destroys their colour.
If they are not likely to be permanently lodged in the
cabinet immediately, it is better that they should be laid on
blotting paper, or a soft cloth, to absorb as much as possible
of the water from within them and then dry them rapidly
before a fire, or in a slack oven, without any previous
washing in freshwater. By this mode they retain a sufficient
amount of moisture and flexibility to allow of their being
handled and operated on for examination with impunity ;
but the amount of salt thus left within them will in time
cause considerable mischief to the specimen. After such
specimens have been once thoroughly dried and their ex-
amination has been completed, they may be plunged into
cold water for a few minutes, and the water then ejected by
a rapid centrifugal motion of the arm, and this operation
repeated two or three times ; the specimen should be again
rapidly dried, and it will then keep well in the cabinet and
preserve all its characteristic features. It is a bad habit to
soak marine specimens for a considerable time in fresh
Avater to extract the salt, as by this mode of proceeding the
minute and delicate characters of the object are to a great
extent destroyed.

The most advisable mode of proceeding in the examina-
tion of an unknown species, is first to note the general
peculiarities of form and surface as presented to the unas-
sisted eye.

After the noting of the external character, the next step
should be to cut a slice out of the sponge, to about half an
inch or more in depth at right angles to the surface, taking

15

226 ANATOMY AND PHYSIOLOGY

special care that a clue proportion of the dermal membrane
is included ; this should be placed in a long narrow test-
tube, in about an inch deep of nitric acid, in which it should
be gently and cautiously boiled over a very small flame
until the sponge is entirely dissolved, and then set by until
the acid is quite cold and the spicula have subsided to the
bottom of the test-tube, so that the greater portion of the
acid may be decanted off and its place be supplied with
distilled water ; and this latter operation should be repeated
three or four times with much care. The spicula thus pre-
pared should be placed in a watch-glass with a little distilled
water, and the whole stirred up so that an average sample
can be obtained for microscopical examination. By this
mode of procedure a general view of the whole of the
spicula belonging to the species will be obtained, which will
serve as a guide to the subsequent modes of examination.

The boiling in nitric acid should not be continued beyond
the time of the piece of sponge falling completely separated
to the bottom. If stopped at this period by the addition
of a little distilled water, it frequently occurs that undis-
solved gemmules and portions of the membranes are found
that are very suggestive for the further examination of the
specimen.

The next step should be to take a thin slice from the
surface of the sponge, and place it in a cell in a little
distilled water, for the purpose of the examination of the
structural peculiarities of the dermal membrane. Then take
a thin slice from the body of the sponge at right angles to
its surface, and mount it in a similar manner for the purpose
of ascertaining the nature and peculiarities of its skeleton
and other internal organs. These two sections should be
carefully examined with the microscope, and if they be not
sufficiently characteristic fresh ones should be mounted. If
the specimens thus treated be taken from sponges properly
preserved, their tissues will expand and assume very much
the appearance of those of the living sponge, and they will
as nearly as possible exhibit the natural positions and pro-
portions of the internal organs.

The general characters of these sections should be observed

OF THE SPONGIAD^E. 227

with a half-inch or two-thirds combination, and again with
not less than a quarter-inch object-glass, and the characters
of the various tissues in their natural condition be immedi-
ately noted. But the whole of their minute organs will not
be visible by this mode of examination, and it is therefore
necessary to mount the same or similar sections in Canada
balsam, by which means the spicula of the sarcode and other
minute organs will become completely visible in situ, and
the specimens thus mounted will serve as permanent records
for the cabinet.

228 ANATOMY AND PHYSIOLOGY

TERMINOLOGY,

AND DESCRIPTIONS OF THE ILLUSTRATIVE FIGURES.

Professor Ehrenberg in the course of his laborious and
valuable researches into the nature of the various minute
organized bodies contained in the earths of recent and
ancient geological deposits, has described a large number
of sponge spicula, which he has named and arranged in
genera and species in accordance with their forms ; but as in
many species of existing sponges we find three or four of
his genera and species of spicula, and in other cases we
find one of his species common to a dozen or more distinct
genera and species of recent sponges, it becomes impossi-
ble systematically to apply the names he has given to these
organs to the descriptions of the living species of Spongiadae
with any degree of propriety or certainty. I have there-
fore been compelled, in constructing a terminology for the
description of the Spongiadae, to consider the names
applied to those organs by my learned and highly esteemed
friend, Professor Ehrenberg, as provisional terms rather
than as permanent denominations, and to designate the
numerous and varied forms of these organs in such a
manner as to render their names as closely descriptive of
their forms as possible, after the manner in which the
nomenclature of botanical organs has been treated by the
best writers on that science.

The quantity of new names, and of figures illustrative of
them, is necessarily large, and to facilitate the references
from the one to the other I have numbered the figures as
a continuous series, and not with reference to each sepa-
rate plate ; and the descriptions of the illustrations are
numbered to correspond with the figures appended to
them, so as to render the references mutual ; and the same
system of reference is applied throughout the work, each
number leading the student to both figure and description.

OF THE SPONGIAD^E. 229

SPICULA OF THE SKELETON.
FIG.

1. ACERATE. — Of the same diameter for the greater

part of the length of the shaft, but decreasing

equally near each termination, and ending acutely

at both. X 160 linear.

The proportions of length and diameter vary to a
considerable extent in this form. In Halichondria
panicea, Johnston, it is of about the medium pro-
portions.

2. In Spent/ilia fluaviatilis it is much shorter and stouter.

X 160 linear.

3. FUSIFORMI-ACERATE. — Having the greatest diameter

at the middle of the shaft, and decreasing gradually
to each acute termination. Halichondria coccinea,
Bowerbank. X 160 linear.

4. INFLATO - FUSIFORM: - A CERATE. — Fusiform! - acerate,

with a globular inflation at the middle of the
shaft. This form of spiculum is abundant in the
skeleton of Isodictt/a anomaJa, Bowerbank. It is
sometimes extremely fusiform in shape. X 160
linear.

5 INEQUI- ACERATE VERMICULOID. — From Hymeraplda
vermiculata, Bowerbank, Shetland. X 175 linear.

6. ACUATE. — Of the same diameter from the hemi-

spherically-terminated base to near the acutely-
terminated apex. Halichondria Alderi, Bower-
bank. X 160 linear.

7. ACUATE. — From Hymeniacidon carnncula, Bowerbank.

X 160 linear.

8. FUSIFORMI-ACUATE. — Having the largest diameter

near the middle of the shaft, and decreasing thence
gradually towards the hemispherical base and the
acute apex. Halichondria crustula, Bowerbank.
X 160 linear.

230 ANATOMY AND PHYSIOLOGY

FlG.

9. ATTENUATO-ACUATE. — Decreasing gradually in dia-
meter from the hemispherical base to the acutely
terminated apex. Halichondria infundibuliformis,
Johnston. X 160 linear.

10. FLECTO- ATTENUATO-ACUATE. — Attenuato-acute bent

suddenly near the base of the spiculum. Isodictya
infundibuliformis, Bowerbank. X 160 linear. In
other species of sponges, and in other forms of
spicula, the bending near the base is not so abrupt
but it is still characteristic and constant in the
species, as for example in the following form :

11. FLECTO-ACUATE. — Halicliondria variantia, Bower-

bank. X 160 linear.

12. CYLINDRICAL. — Having the shaft of the same diameter

throughout its length, and terminating at each
end hemispherically, as in Pacliymatisma John-
stonia, Bowerbank. X 90 linear.

13. FARCIMULO-CYLINDRICAL. — From Spongilla coral-

loides, Bowerbank. In the Museum of the Royal
College of Surgeons. X 108 linear.

14. NODULATED - CYLINDRICAL VERMICULOID. — From

soundings in the Atlantic 2070 fathoms. X 175
linear.

15. FUSIFORMI-CYLINDRICAL. — Having both terminations

hemispherical, and the shaft gradually increasing
in diameter to its middle. Pachymatisma John-
stonia, Bowerbank. X 90 linear.

— . DOLIOLATE-CYLINDRICAL. — See No. 94, and same
number, Plate IV.

16. FLEXUOUS-CYLINDRICAL. — Having the shaft of the

spiculum curved repeatedly. From Phakellia
ventUabrum, Bowerbank. X 160 linear.

17. ATTENUATO-CYLINDRICAL. — Terminating hemispheri-

cally at both ends, but the shaft slightly decreasing
from the base to the apex. Pacliymatisma John-
stonia, Bowerbank. X 90 linear.

OF THE SPONGIAD^E. 231

FIG.

18. FUSIFORMI-ATTENUATO CYLINDRICAL. — Both termina-

tions being hemispherical, the fusiform shaft has a
much smaller diameter towards its apex than it
has at its base. From Tethea robusta, Bower-
bank, MS. A new species from Australia, in the
British Museum. X 90 linear.

19. BICLAVATED CYLINDRICAL. — The shaft equally cylin-

drical, with gradually inflated terminations. The
inflations are almost as great as that of a spinulate
spiculum, but without sphericity. From a new
and undescribed species from Australia, Bower-
bank collection. X 260 linear.

20. iNEQui-BicLAVATED CYLINDRICAL. — The shaft atten-

uated from the base to the apex, with clavated
terminations of unequal diameters. From Pacliy-
matisma Johnstonia, Bowerbank. X 90 linear.

21. ANGULATED INEQUI-BICLAVATED CYLINDRICAL. — This

singular angulated form does not appear to be
purely accidental, as I have found other instances
of similar angulation at the middle of the shaft in
other sponges, and the angle in each instance has
been as nearly as possible at the same spot in the
shaft. Pachymatisma Johnstonia, Bowerbank.
X 90 linear.

22. SPINULATE. — Shaped like a pin, having the same

diameter from the spherical base to very near the
acutely terminated apex. Hymeniaddon carnosa,
Bowerbank. X 260 linear.

23. FUSIFORMI-SPINULATE. — The base being spherical,

the shaft more or less fusiform and terminated
acutely. Hymeniaddon suberea, Bowerbank. X
260 linear.

24. DEPRESSO-SPINULATE. — Having the basal inflation

considerably depressed, the shaft having the same
diameter to very near the apex. From an unde-
scribed species of sponge from Ash Island. X
160 linear.

232 ANATOMY AND PHYSIOLOGY

FIG.

25. OVO-SPINULATE. — The basal inflation being oviform,

the smallest portion being at the extreme basal
point. From Tetliea spimtlaria, Bowerbank. X
308 linear.

26. EXORMI-SPINULATE. — Having the spherical inflation

slightly within the basal portion of the shaft of
the spiculum. Hymeniacidon celata, Bowerbank.
X 260 linear.

— . BISPINULATE. — See No. 228, and Plate X, same
number.

— . TRISPINULATE. — See No. 229, and Plate X, same
number.

27. ENSIFORM. — Expanding towards the apex, but ter-

minating acutely ; so that the outline has more or
less the form of the blade of a sword. Sponge
unknown. X 130 linear.

28. ENTIRELY SPINED. — When the spines are equally

dispersed over the spiculum from the base to the
apex. Halicfiondria incrustans, Johnston. X
260 linear, Pages 38, 40.

29. B AS ALLY SPINED. — When the spines do not occupy

more than about one-third of the length at the
basal portion of the spiculum. Halicliondria In-
galli, Bowerbank. X 260 linear.

30. MEDIALLY SPINED. — When the spines occupy only

about one-third of the length at the middle of the
spiculum. Halicliondria Ingalli, Bowerbank. X
260 linear, Page 38.

31. APICALLY SPINED. — When the spines occur only at

and near the apex of the spiculum : from an unde-
scribed sponge, locality unknown. X 160 linear.

32. TERMINALLY SPINED. — When the spines occur near

both the base and apex of the shaft of the spiculum
but not at the middle : from an un described species
of sponge, locality unknown. X 160 linear, Page
38.

OF THE SPONGIADJE. 233

FIG.
33. SUB-ATTENUATO ENTIRELY SPINED CYLINDRICAL.

From Hymeniacidon Cliftoni, Bowerbank, MS.
Freemantle, Western Australia. X 400 linear.

34. CLAVATO-ATTENUATO-CYLINDRICAL, APEX STELLATELY

SPINOUS. — From Hymerapkia sf el/if era, Bower-
bank. X 260 linear. All the spicula of this
sponge appear to combine the offices of skeleton
and defensive spicula, Page 189.

35. ELONGO-ATTENUATO- STELLATE. — Having the radii

springing from an elongated instead of a central
base. This form of spiculum occurs abundantly
in Tetliea vmricata, Bowerbank, MS. From
Vigten Island, Norway. It is both externally and
internally defensive. X 308 linear, Page 22.

36. EQUIANGULAR TRIRADIATE. — Having the three attenu-

ating rays in the same plane, and the intervening
angles equal, or very nearly so. Grantia com-
pressa, Fleming. X 160 linear, Page 163.

37. RECTANGULAR TRIRADIATE. — Having the three attenu-

ating rays in the same plane, two of them forming
a straight line, and one being projected from the
middle of the line, forming right angles to it.
Abundant in the base of the ciliary fringe of the
mouth of the cloaca of Grantia tessellata, Bower-
bank. X 260 linear.

38. ELONGO-EQUIANGULATED TRIRADIATE. — From Grantia

striatula, Bowerbank, MS. X 108 linear. Ma-
deira. Exhibiting an extreme development of the
elongated ray. This form occurs also in the
intermarginal cavities in Grantia compressa.

39. EXFLECTED ELONGO-EQUIANGULATED TRIRADIATE.

From Grantia striatula, Bowerbank, MS. XlOS
linear. Madeira. Abundant on the surface of
the pedicel of the sponge ; and also Grantia
compressa, see Fig. 312.

40. EQUIANGULAR TRIRADTATE. — A very stout variety of
form, from an undescribed African calcareous
sponge. X 90 linear.

234 ANATOMY AND PHYSIOLOGY

FIG.

41. TRIFURCATED PATENTO-BITERNATE. — Consisting of a

short stout shaft, each end being furnished with
three short equiangular radii passing off at right
angles to the shaft, and each having its termina-
tion trifurcated. X 90 linear. This singular
form occurs in the tortuous excavations of pro-
bably a small annelid in a soft limestone, the
sponge lining the cavities in a manner similar to
Hymeniacidon celata, Bowerbank. The skeleton
consists entirely of this singularly complicated
form of spiculum.

42. A view of one end of the spiculum represented by

Fig. 41. X 90 linear.

43. BIANGULATED QUADRiRADiATE- — Having two radii

projected from a common basal point, in one
plane forming an angle of about 90°, and the
other two projected in a similar manner in an
opposite direction in a second plane at right
angles to the first one. X 90 linear.
This singular form is associated with the spiculated
triradiate one in the skeleton of Hymeniacidon Buck-
Ian di, Bowerbank.

44. EQUIANGULAR SPTCULATED-TRIRADIATE. — Having the

three rays in the same plane with the intervening
angles equal, and a fourth ray projected from the
basal junction of the radii at right angles to their
plane. Hymeniacidon BucMandi, Bowerbank.
X 90 linear.

This form is very common in the calcareous
sponges, where it appears as a defensive organ.

CONNECTING SPICULA.

45. EXPANDO-TERNATE. — Having the terminal radii pro-

jected forward at angles varying from 45 to 60 or
70 degrees to the long axis of the shaft. From
Pachymatisma Johnstonia, Bowerbank. X 90
linear.

OF THE SPONGIADJE. 235

FIG.

— . EXPANDO-TERNATE. — See No. 128, and Plate V, same

number.
— . INCURVO-PORRECTO-TERNATE. — See No. 129, and

Plate V, same number.
— . BIFURCATED EXPANDO-TERNATE. — See No. 130, and

Plate V, same number.

46. CYLINDRO EXPANDO-TERNATE. — Prom Packymatisma

Johnstonia, Bowerbank. X 90 linear. Probably
an incomplete development of the form represented
by Fig. 45, Page 18.

47. PATENTO-TERNATE. — Having the terminating radii

disposed at, or nearly at right angles to the shaft
of the spiculum, the curves of the radii being
usually more or less inclined backwards towards
the base of the shaft. From Geodia McAndrewii,
Bowerbank, MS. X 90 linear. Vigten Island,
coast of Norway.

48. GENICULATED EXPANDO-TERNATE. — From Tetliea Col-

lingsii, Bowerbank. X 108 linear. The shaft
acts as a subsidiary skeleton spiculum, and the
ternate apex as a defensive one.

49. ABBREVIATO-PATENTO-TERNATE. — From a sponge

allied to Packymatisma in the Museum of the
Royal College of Surgeons. X 108 linear. A
completely developed spiculum.

50. FURCATED ATTENUATO-PATENTO-TERNATE. — The radii

of the ternate apex having bifurcated terminations
in the same plane as the primary radii. From
Pachymatisma Listen, Bowerbank, MS. X 90
linear.

51. The same spiculum represented by Fig. 50. The

former being erect, and the latter having the plane
of the radii presented to the eye. X 90 linear.

52. IRREGULARLY FURCATED PATENTO-TERNATE. — From

the dermis of Daclylocalyx Prattii, Bowerbank,
MS. X 90 linear.

236 ANATOMY AND PHYSIOLOGY

FIG.

53. SPICULATED DICHOTOMO-PATENTO-TERNATE. — A still

more complicated form than that of the Furcated
patento-ternate one. The radii of the bifurcations
each terminating again dichotomously ; but the
secondary bifurcations are not all of them in the
same plane as the primary ones, a portion of them
being; at right angles to it, and the shaft is also

O o o

carried through the common central base of the
whole, giving it a spiculated form as represented
in the figure. X 260 linear. Sponge unknown.
Similar spicula occur abundantly in the dermis of
DactyJocatya; Boiverbcmkii, Johnson, in the British
Museum. X 260 linear, Page 18.

54. RECURVO-TERNATE.— -The terminating radii, recurved

from about 100 to 140 degrees from the apical
line of the axis of the shaft. The curves of the
radii are always more or less inclined towards the
base of the shaft of the spiculum. From Geodia
Barretti, Bowerbank, MS. X 90 linear. Page
123.

55. SPICULATED RECURVO-TERNATE. — Having three equi-

distant recurved radii, and the central terminal one
porrect in the line of the axis of the shaft of the
spiculurn. From Geodia Barretti, Bowerbank,
MS. X 90 linear. Page 22.

56. The central porrect terminal ray is often more or less

deflected from the axial line of the shaft, as in
Fig. 56; and occasionally, in the simple recurvo-
ternate form, one of the three rays will be bent
upward, even to a greater extent than is repre-
sented in Fig. 57 ; but these it must be recollected,
are but accidental variations in form.

57. The shafts of the recurvo-ternate forms of spicula are

much less in diameter than those of the patento or
expando-ternate ones from the same sponge, and
they are frequently very long and exceedingly
attenuated.

OF THE SPONGIAD^E. 237

FIG.

58. SPICULATED PORRECTO-TERNATE. — Having three equi-
distant porrect terminal rays, and a fourth or
central one in a line with the axis of the shaft.
From Geodia Barretti, Bowerbank, MS. X 90
linear.

PREHENSILE SPICULA.

59. APICALLY SPINED RECURVO -QUATERNATE. — From
Euplectella cucumer, Owen. X 90 linear. Pro-
jected from the basal portion of the sponge as a
means of attachment to other bodies. The recurvo-
quaternate end (a) being the apex of the spiculum.
Page 20.

DEFENSIVE SPICULA.

60. MULTIDENTATE BiROTULATE. — Hyalonema mirabilis,

Gray. X 83 linear. This form is more especially
a retentive spiculum ; an auxiliary to the offensive
and defensive spiculated cruciform spicula with
which it is associated in the interstitial cavities of
the sponge. Fig. 294.

From the basal portion of a specimen in the British
Museum. Pages 37 and 127.

61. ELONGO-RECURVATE DENTATO-BIROTULATE. — From the

same sponge as Fig. 60. X 308 linear.

62. RECURVO - ACUTELY DENTATE - BIROTULATE. — From

soundings in the Indian Ocean, 2200 fathoms ;
probably from an unknown species of Hyalonema.
X 308 linear.

63. ELONGO-RECURVATE DENTATO-BIROTULATE. — From

soundings in the Indian Ocean, 2200 fathoms; from
most probably an unknown species of Hyalonema.
X 308 linear.

238 ANATOMY AND PHYSIOLOGY

FIG.

64. RECURVO-DENTATO-BIROTULATE. — From soundings in

the Indian Ocean, 2200 fathoms. Most probably
from another unknown species of Hyalonema.
X 308 linear.

65. INFLATO - FUSIFORMI » ACERATE ASCENDINGLY HEMI-

SPINOUS. X 108 linear. — Hyalonema miradilis,
Gray, British Museum. Projected in abundance
from the dermal surface of the sponge ; the smooth
basal half being immersed in the tissues beneath
the dermal membrane and the spinous distal por-
tion being projected beyond it. Purely external
defensive.

66. ATTENUATO-ACU ATE, ENTIRELY SPINED. — From Dictyo-

cylindrus ventilabrum, Bowerbank. X 260 linear.
Internal defensive. Page 29.

67. ACUATE, ENTIRELY AND VERTICILLATELY SPINED.

From an undescribed sponge, X 400 linear. Inter-
nally defensive. I have found it in two distinct
species of sponge from the West Indies. In one
it is irregularly dispersed, and in the other it is
collected into radiating groups. See Figs. 289,
290, Page 30.

68. CYLINDRICAL : ENTIRELY AND VERTICILLATELY
SPINED. X 400 linear. — I am not acquainted
with the sponge whence this beautiful spiculum
came. I found it in the refuse matter from the
base of a specimen of Oculina rosea, from the
South Seas. The shaft of the spiculum, from end
to end, has equidistant rings of single series of
acute conical spines, and the base and apex of the
spiculum are each equally crowded with spines. I
have arranged it as a defensive spiculum, from its
near approximation to the characters of the spicu-
lum last described ; but it is subject to the doubt
whether it may not ultimately prove to have be-
longed to the skeleton. Page 30.

OF THE SPONGIAD^E. 239

FIG.

— . ATTENUATO-CYLINDRICAL VERTICILLATELY SPINED. —
See 210, 238, and 239. And Plate X, same num-
bers.

69. VERTICILLATELY SPINED CYLINDRICAL. X 660 linear.
— From an undescribed sponge from Freemantle,
Western Australia. Very abundant on the dermal
and interstitial membranes. Internally and exter-
nally defensive.

70. SUB-ATTENUATO-ENTIRELY SPINED CYLINDRICAL. X

400 linear. — From Hymeniacidon Cliftoni, Bower-
bank, MS., Freemantle, Western Australia. In-
ternal defensive.

71. MULTIANGULATED CYLINDRICAL. X 400 linear. —

From a sponge in the British Museum ; accident-
ally entangled in its tissues. The same form occurs
in the interstitial membranes of Geodia carinata,
Bowerbank, MS., figured in Plate xxxvi, F'ig. 42,
' Phil. Trans.,' 1858, page 314.

72. SPINULO-MULTIANGULATED CYLINDRICAL. X 660. — •

Found among the extraneous spicula of the same
sponge that produced the one represented by Fig.
71. It is in the Johnstonian collection in the
British Museum. It is designated Halichondria
sanguince, and its register is 47. 9. 7.19.

73. SPINULO-RECURVO-QUATERNATE. X 130 linear. —

Representing its first stage of development. Page
34.

74. The same form of spiculum as represented by Fig. 73,

in its second stage of development. X 130 linear.

75. The same form of spiculum as represented by Fig.

73, in its third stage of development. X 130
linear.

76. The same form of spiculum as represented by Fig. 73,

in a completely developed state. X 130 linear.
From an undescribed species of sponge. Locality
unknown. Internally defensive. See Plate XVIII,
Fig. 292. The gradual development of this form of
spiculum is very instructive. Pages 32, 33, and 34.

240 ANATOMY AND PHYSIOLOGY

TIG.

77. FUSIFORMI-PORRECTO-TERNATE, a very early stage of
development, from Tethea cranium, Johnston. X
660 linear.

7-S. A further stage of development of a fusiformi-porrecto-
ternate spiculum from Tetliea cranium, Johnston.
X 260 linear.

79. An adult fusiformi-porrecto-ternate spiculum from

Tetliea cranium, Johnston. X 160 linear.

80. A fusiformi-porrecto-ternate spiculum from Tethea

cranium, Johnston, charred to exhibit the cavities
of the shaft and radii. X 260 linear.
These spicula form the greatest portion of the fasci-
culi of defensive spicula with which the external surface
of Tethea cranium is armed. They are very long and
slender, frequently exceeding a quarter of a inch in
length, with a diameter of i^th of an inch at the
thickest portion of the shaft. The ternate radii are
projected from the apex of the shaft at about an angle
of 20° from its axis, and are about j^th of an inch in
length. See Fig. 362, a, Plate XXXI.

81. FUSIFORMI-RECURVO-TERNATE spiculum, in an early

stage of development, from Tethea cranium, John-
ston. X 260 linear. Page 32.

82. FUSIFORMI-RECURVO-TERNATE, an adult spiculum from

the same sponge as the spiculum represented by

Fig. 81. X 260 linear. Page 32.

This form of defensive spiculum occasionally ac-
companies the porrecto-ternate ones of the defensive
fasciculi of Tethea cranium. The length and propor-
tions of the shaft of the former are very much the same
as those of the latter. The recurvate apex of the
spiculum undergoes a progressive development, which
does not appear to commence until after a great
extent of the length of the slender flexible shaft has
been produced, when an enlargement of the apex of
the shaft takes place, and the rudiments of the stout
recurvate radii appear as represented by Fig. 81, and
between this and the fully-developed form, fig. 82, all

OF THE SPONGIAD^E. 241

FIG.

the intermediate gradations of development may be

observed among the spicula of young specimens of

the sponge. The two figures are drawn by the same

power, 260 linear, and the difference in size between

the young and the fully-developed spiculum is very

remarkable.

This form is both defensive and retentive, internally

and externally. See Fig. 354e>, Plate XXVIII, and

Pig. 362 c, Plate XXXI.

83. ATTENUATO-CLAVATE : INCIPIENTLY SPINED. — The

enlargement of the base of this spiculum is not
spherical as in a spinulate form, but it expands more
or less gradually and is usually exaxial. They are
projected in abundance into all parts of the inter-
stitial cavities of Hymcniacidon davigera, Bower-
bank. X 130 linear.

84. EQUIANGULAR TRIRADIATE : VERTICILLATELY SPINED.

— This beautiful spiculum was found among
minute fragments of various sponges scraped from
the bases of specimens of Oculina rosea. I have
not hitherto found verticillately spiiied sponge
spicula under any other character than that of de-
fensive spicula, and I have therefore arranged this
one as such until further information shall be ob-
tained regarding it. X 400 linear.

85. ENSIEORM SPICULATED EQUIANGULATED TRIRADIATE.

— The spicular ray is at right angles to the com-
mon plane of the basal radii, but not of the same
form. It is very much longer and stouter than
the basal radii, and its diameter is considerably
increased in the distal third. Internal defensive.
X 130 linear. Prom the cloaca of Grantia ensata,
Bowerbank. Page 29.

86. A variety of the same form of spiculum as that repre-

sented by Pig. 85. Prom the cloaca of Grantia
tessettata, Bowerbank. X 130 linear. See Pig.
286, Plate XVII, in situ. Page 29.

16

242 ANATOMY AND PHYSIOLOGY

FIG.

87. SPICULATED EQUIANGULATED TRIRADIATE. — When the

spicular ray is of the same form and at right angles
to the common plane of the basal radii, from Leu-
conia nivea, Bowerbank. X 45 linear. Page 29.

88. EQUIANGULATED TRIRADIATE: TJNIRADIALLYSPINED. —

I obtained a considerable number of this form of
spiculum from the dissolution in nitric acid of a
small fragment of a parasitical sponge, in the col-
lection of the late Mr. Charles Stokes. I have not
seen it in situ, but I have very little doubt from its
structure that the spiculated ray is a defensive one,
while the two spineless rays formed part of the
skeleton. X 130 linear.

89. EQUIANGULATED SPICULATED TRIPODATE. — When the

basal radii are projected backward so that their
apices only are in the same plane, and the spicular
ray at right angles to that plane. The short spicu-
lar ray in this case is not based on a triradiate
skeleton one, but the whole speculum is essentially
a defensive one only. They occur in the lining
membrane of the cloaca of Leuconia nivea, Bower-
bank, and are very minute. X 660 linear.

-. SPICULATED INEQUI-ANGULATED TRIRADIATE, WITH
CYLINDRICAL ENTIRELY SPINED RADII. See No.
234, and same number, Plate X.

— . SPICULATED ATTENUATO - EQUIANGULAR : VERTICIL-
LATELY SPINED. See No. 235, and same number,
Plate X.

— . SPICULATED CYLINDRO-EQUIANGULAR TRIRADIATE:
VERTICILLATELY SPINED. See No. 236, and same
number, Plate X.

— . INEQUI-FURCATO-TRIRADIATE. See No. 237, and same
number, Plate X.

OF THE SPONGIAD^I. 243

SPICULA OP THE MEMBRANES.

TENSION SPICULA.

FIG.

90. FUSIFORMI-ACERATE : ENTIRELY SPINED. X 660

linear. — This form of spiculum occurs abundantly
in the dermal and interstitial membranes of Spon-
yilla lacustris, Johnston. Pages 38, 42, and 58.

91. PUSIFORMI-ACERATE : TRUNCATEDLY SPINOUS. X 660

linear. — Abundant in Spongilla alba, Carter, in
both the dermal and interstitial membranes. Page
42.

92. MUCRONATO - CYLINDRICAL. X 400 linear. — The
dermal membrane of Halichondria incrustans,
Johnston, is abundantly furnished with large flat
fasciculi of this form of spiculum. They are as
long as those of the skeleton, but not above half
their diameter ; they are entirely destitute of spines,
while the spicula of the skeleton are covered with
those organs. Page 40.

— . TERMINALLY SPINED SUBFUSIFORMI-CYLINDRICAL. —
This form of spiculum is abundant in the dermal
membrane of Halichondria niyricans, Bowerbank,
where it occurs in irregular fasciculi. It is as long
as the spicula of the skeleton, but has not quite
so great a diameter, and is distinctly different in
its form.

93. TUBERCULATED FUSIFORM1-CYLINDRICAL. X 660

linear. — These minute spicula are profusely dis-
persed on the inner surface of the dermal and inter-
stitial membranes of Pacliymatisma Johnstonia,
Bowerbank. They are covered very irregularly
with ill-defined tubercles. They vary very con-
siderably in form and proportions. Their average
dimensions are, length g^th inch, diameter
inch. Page 42.

244 ANATOMY AND PHYSIOLOGY

FIG.

94. DOLIOLATE CYLINDRICAL. X 175 linear. — From a

sponge nearly related to Ecionemia, Bowerbank.
Locality unknown. From the similarity of the
form to Fig. 93, it is probably a tension spi-
culum.

95. INFLATO-CYLINDRICAL. X 660 linear. — This form of

spiculum is very minute. It is slightly curved,
and has a single, well- denned bulbous inflation near
the middle of the shaft, but in this respect, as well
as in size, there is, comparatively, a considerable
amount of variation. The normal condition of the
inflation is equidistant from the ends of the spi-
culum, but in some cases it is not more than a
third of the length of the spiculum from one
end of it. The only sponge in which I have found
this form is Hymeniacidon ficus, Bowerbank, where
it occurs in the dermal membrane in great pro-
fusion.

96. TRICURVATO-ACERATE. X 260 linear. — This form of

97. spiculum has always three curves in the course of

98. its length, one at the middle of the shaft, and one
near each termination, the terminal ones curving in
the same direction, and always opposite to that of
the central curve.

These spicula vary greatly in form and proportions
in different sponges, and frequently even in the same
species. The normal form is that of three curves of
about equal value, (Fig. 96,) but sometimes, as in
Fig. 97, the central curve is very much the larger of
the three, while in Fig. 98 we find the extreme con-
dition of the form, the spiculum being comparatively
straight, with a very small curve in the centre of the
shaft, and the terminations exhibiting only the rudi-
ments of curves in an opposite direction to the middle
one. They are usually very much more slender than
the spicula of the skeleton, and are comparatively of
rare occurrence in every species in which I have found
them. I have never seen them in situ with the ter-

OF THE SPONGIAD^E. 245

FIG.

minal curves elevated above the surface of the mem-
brane, but always reposing on one side, with all parts
of the shaft closely attached to its surface. The three
forms figured are from the same specimen of sponge.
Page 41.

99. UNICURVO-CRUCIFORM. X 130 linear. — This form
occurs abundantly on the membrane lining the
great cloacal cavities of Leuconia nivea, Bower-
bank. The axial radii are disposed very nearly
in the direction of the long axis of those organs, and
the curves formed by the lunate radii always have
their points towards the mouths of the cloaca.

100. FALCATO-ACERATK. X 130 linear. — This form is

abundant in a small species of Grantia from
Australia, which is found on several species of Fuci
in the collections brought home by Dr. Harvey.
The sponges do not frequently exceed the eighth of
an inch in length. Page 41.

101. BICURVO-ACERATE. X 260 linear. — This form is

from a small parasitical Grantia from Algoa Bay,
in my collection. The sponge is about the size of
a large pea, and is not uncommon on Zoophytes
from that locality. Page 41.

102. 103, 104, 105, 106, 107, 108. FOLIATO PELTATE.

These spicula have the shaft exceedingly short and
conical ; the basal termination being acute, and the
shaft dilating rapidly to its distal end, to the extent
of an angle of about 1 5 or 20 degrees. The apex of
the spiculum expands into a large, more or less,
circular disc or shield, having in the fully developed
state an extremely sinuous or foliated margin ; the
plane of the shield or disc being at about right angles
to the line of the shaft, and having the under side thickly
studded with tubercles, which are separate in the
young spicula, and more or less confluent in the fully
developed ones. In an early stage of its development

246 ANATOMY AND PHYSIOLOGY

PIG.

the peltate apex of the spiculum is irregularly circular,
and entirely devoid of the complex and beautiful
sinuous foliations that render the adult spicula such
elegant objects. Pig. 102. X 260 linear. As the
development proceeds it assumes a trilobular shape,
Fig. 103, X 160 linear, and the margins are slightly
indented or serrated.

In a further advanced condition, the sinuation of
the margin becomes deeper and more complex, as
represented in Figs. 104, X 160 linear, and 105,
X 160 linear, until at last it becomes, in the fully
developed peltate apex, so deeply and irregularly
sinuated as to nearly obliterate all traces of its ori-
ginal trilobular character (Fig. 106). X 130 linear.
Fig. 107, X 160 linear, represents a side view of a
spiculum exhibiting the form and comparative length
of the shaft. Fig. 108, X 260 linear, exhibits the
furcated terminations to two out of the three radiating
canals of the apex of the spiculum.

RETENTIVE SPICULA.

109. SIMPLE BIHAMATE. — Acerate spicula, having each end

of the spiculum curved in the form of a hook in
the same plane and towards each other. From
Halichondria variantia, Bowerbank, X 1060
linear, Page 43.

110. REVERSED BIHAMATE SPICULA. — Having each end of

the spiculum curved in the form of a hook in the
same plane, but in opposite directions to each
other. From Halichondria incrustans, Johnston.
X 1060 linear.

111. CONTORT BIHAMATE SPICULA. — Having each end of

the spiculum curved in the form of a hook but in
planes at right angles to each other. From Hali-
chondria incrustans, Johnston. X 1060 linear.

OF THE SPONGIAD^l. 247

PIG.

112. TRENCHANT CONTORT BIHAMATE. — Shewing the cylin-

drical form of the shaft at the curves of the hooks,
and the middle of the spiculum, and the trenchant
edges of the remainder of its inner surface. X
400 linear. Hymedesmia JoJmsoni, Bowerbank,
MS. From Madeira, Pages 35, 127.

113. ABBREVIATED BIHAMATE. — From an unknown sponge.

X 1060 linear. I have found but very few speci-
mens of this form, and in no case in situ ; and I
am therefore in doubt whether it be an adult
spiculum, or merely a variety arising from an
arrest of development.

114. DEFLECTED BIHAMATE. — When the hami are both

deflected in the same direction at nearly right
angles to the plane of the shaft. From Farrea
occa, Bowerbank, MS. The sponge is at the base
of Eu/plectella ciicumer, Owen. X 660 linear.

115. EXTER-UMBONATE BIHAMATE. — When the limbo is on

the middle of the outer curve of the shaft ; from an
undescribed sponge from Sicily. X 1060 linear,
Page 45.

116. INTER-UMBONATE BIHAMATE. — When the umbo is on

the middle of the inner curve of the shaft ; from the
same sponge as Fig. 115. X 1060 linear. Page
45.

117. BI-UMBONATE BIHAMATE. — When the middle of both

the inner and outer curve of the shaft have an
umbo. From the same sponge as Fig. 115. X
1060 linear. Page 45.

118. UNICLAVATE BIHAMATE. — I believe to be an arrest of

development rather than a separate form ; for
although I found many specimens of it intermixed
with the biclavate forms, I also found others
assuming transitional forms, that appeared ulti-
mately to connect it with the biclavate spicula.
X 1060 linear. Page 44.

248 ANATOMY AND PHYSIOLOGY

FIG.

119. BTCLAVATE BIHAMATE. — There is a considerable varia-

120. tion in the shape of this spiculum. The form
represented by Pig. 119 is perhaps the most numer-
ous, but that of Fig. 120 is the largest and most
fully developed. X 1060 linear. Page 44.

121. BICALCARATE BIHAMATE. X 1250 linear. — This

singular and minute form of spiculum has hitherto
been found only in Isodictt/a Normani, Bowerbank.

122. QUADRIHAMATE. From Hyalonema mirabilis, Gray.

X 1250 linear. — They are dispersed in considerable
numbers on the interstitial membranesof thesponge.

123. UNIPOCILLATED BIHAMATE. X 1060 linear. — One

termination fully developed in the form of a cup,
while the other is only produced to the extent of
the two lateral curves, and a terminal umbo to the
shaft. HalichondriaHyndmanifiQwe^smk. Page44.

124. SIMPLE BIPOCILLATED BIHAMATE. — X 1060 linear.

Having both terminations developed in the form of
cups in coincident planes. Halichondria Hynd-
mani, Bowerbank. Page 44.

125. CONTORT BIPOCILLATED BIHAMATE. X 1060 linear. —

Two cups being developed, but in planes at right
angles to each other. Halichondria Hyndmani,
Bowerbank. Page 44.

126. UMBONATED BIPOCILLATED BIHAMATE. X 1060

linear. — Having a slight prolongation of the shaft
through the distal edge of one or both of the cups ;
in this case through the distal edge of the lower
one only. Halichondria Hyndmam, Bowerbank.
Page 29.

127. A view in profile of a unipocillated spiculum, X 1060

linear : the upper part of the figure represents a
side view of the cup, while the termination of the
lower portion is more than usually elongated ;
showing how the umbonation is produced on
the distal edge of the spiculum, represented by
Fig. 126, Halichondria Hyndmani, Bowerbank.
Page 44.

OP THE SPONGIAD.E. 249

FIG.

128. EXPANDO-TERNATE. X 108 linear. — From a portion

of the skeleton of a sponge nearly allied to Ecio-
nemia, Bowerbank. The shaft acting as a skeleton
spiculum, while the apex serves as an external
defence. Locality unknown.

129. INCURVO-PORRECTO-TERNATE. X 1 OS linear. — From

the same sponge as Fig. 128. The shaft belong-
ing to the skeleton, and the ternate apex acting as
an external defence.

130. BIFURCATED EXPANDO-TERNATE. X 108 linear. —

From the same sponge as Fig. 128. The shaft of
the spiculum assisting in the formation of the
skeleton, while the ternate terminations act as ex-
ternal defences.

131. INEQUI-TRIIIOTULATE. X 660 linear. — (See Plate X.)

Having two terminal rotulse of equal size, and one
intermediate of greater diameter than the terminal
ones. I have no knowledge of the sponge from
which this spiculum is derived.

132. INEQUI TRIHOTULATI. X 660 linear. — (See Plate X.)

From an undescribed sponge in the cabinet of my
friend Mr. George Clifton, Freemantle, Western
Australia. This and the following two forms are
abundant on the interstitial membranes of the
sponge, and vary in form and extent of develop-
ment exceedingly.

133. ECCENTRIC TRIROTULATE. X 660 linear. — -(See Plate

X.) From the same sponge as 132. This specimen
is both centrical and eccentrical to a certain extent.
Page 45.

134. ECCENTRIC TRIROTULATE. X 660 linear. — (See Plate

X.) Exhibiting the fully-developed axial eccen-
tricity. Page 45.

135. TORQUEATO-TRIDENTATE INEQUI-ANCHORATE. X 400

linear. — From a circular group on the interstitial
membranes of an undescribed species of Hymenia-
cidon, from Freemantle, Australia. Page 49.

250 ANATOMY AND PHYSIOLOGY

FIG.

136. TORQUEATO-BIDENTATE INEQUI-ANCHORATE. X 308

linear. — From an un described species of sponge.
Freemantle, Western Australia.

137. BIDENTATE INEQUI-ANCHORATE. X 660 linear. —

From an undescribed species of sponge from the
coast of Sicily. Page 46.

138. PALMATED INEQUI-ANCHORATE. From an unde-

scribed sponge. X 660 linear. — Having the distal
termination largely developed in the form of a
cordate palm, while the proximal end is produced
to a much less extent, is compressed laterally, and
has the terminal point expanded into a short broad
tooth. Pages 46, 47.

1 39. DENTATO-PALMATE INEQUI-ANCHORATE, from Spongia

lodata, Montagu ; Isodictya lobata, Bowerbank.
X 1 060 linear. — Having the distal spatulate palm
produced to the extent of about half the length of
the spiculum, while the proximal one is developed
in the same form to only about one-fourth the
length of the spiculum, and having the apices of
the hami produced beyond the extremities of the
palms, each in the form of a short obtuse tooth.
Sponge in the collection of Professor Grant.

140. TRIDENTATE EQUI-ANCH ORATE. X 660 linear. — •

Having each termination equally and fully de-
veloped, in the form of two lateral and slightly
palmate, and one central attenuated tooth. From
an undescribed sponge in the collection of Mr.
George Shadbolt. Page 47.

141. DENTATO-PALMATE ANGULATED ANCHORATE. X 1060

142. linear. — I have found this form of spiculum only

143. in Spongia plumom, Montagu. Each of the hami
appears as if forcibly compressed towards the
termination of the shaft, which seems to have been
equally influenced by the compression, so that the
hami have become angulated, as represented in the
profile view of one of the spicula. Fig. 143. The
whole of the spicula are dentato-palmate, and the

OF THE SPONGIAD^E. 251

FIG.

adult ones have the terminations of the hami
strongly produced, as represented in Fig. 141,
while in the immature spicula, although the palms
are fully produced, the tooth appears in a rudi-
mentary condition, as Fig. 142, Pages 46 and 47.

144. DENTATO-PALMATE INKQUI-ANCHORATE. X 260

linear. — First stage of development. Page 48.

145. DENTATO-PALMATE INEQUI-ANCHORATE, second stage

of development. X 260 linear. Page 48.

146. DENTATO-PALMATE INEQUI-ANCHORATE, third stage of

development. X 260 linear. Page 48.

147. DENTATO-PALMATE INEQUI-ANCHORATE, an adult

spiculum, showing the fully-produced distal ter-
minal hastate tooth. X 260 linear. Page 47.
See also Fig. 297, Plate XVIII, for the same form
of spiculum in sitit, from Hymeniacidon lingua,
Bowerbank. X 308 linear.

148. DENTATO-PALMATE INEQUI-ANCHORATE. — From the

same sponge as Fig. 147, showing the effects of
incomplete development or malformation. X 260
linear.

149. EXPANDO-TRIDENTATE EQUI-ANCHORATE. X 1250

linear. — From an undescribed sponge in the
British Museum. The shaft is frequently curved
to the extent of nearly a semicircle. Expando-
bidentate forms are mingled with the tridentate ones.
150. TRIDENTATE FIMBRIATED EQUIANCHORATE. X 660
linear. — From Isodictya Jimbriata, Bowerbank,
Shetland. The spicula of this form may be traced
from the earliest stage of development, with
scarcely a trace of fimbriation to the adult spicu-
lum. Fig. 150. They are very abundant on the
interstitial and dermal membranes, and mixed with
them there are many that are only bidentate, but
which are as completely nmbriated as the tri-
dentate ones. The fmibrise are very delicate and
translucent, and require a careful management of
the light to render them apparent.

252 ANATOMY AND PHYSIOLOGY

FIG.

151. BIPOCILLATED EQui-ANCHoRATE. X 1166 linear.—

See Plate XXXVII. Each termination of the shaft
is developed equally in the form of a cup. They are
abundantly dispersed in a recumbent position on
the interstitial membranes of the sponge. From
an undescribed species of Desmacidon, which I
received from my late friend, Mr. Thomas Ingall.
Locality unknown.

152. NAVICULOID SPICULUM. X 660 linear. — See Plate

XXXVII. From a new species of Hymedesmia in
the cabinet of Geo. Clifton, Esq., Freemantle,
Western Australia. I received a small portion of the
sponge mounted in Canada balsam. The spicula are
abundantly dispersed over the interstitial mem-
branes of the sponge, but principally in the vicinity
of the skeleton fasciculi. They vary to some extent
in form, but the one figured represents the general
structure. A keel like rib may occasionally be
observed, in addition to the two marginal ones ;
and the depth of the depression from the plane of
the marginal ribs is much greater in some than in
others. The nearest alliance in form to this spi-
culum appears to be that of the tridentate fim-
briated equi-anchorate represented by Fig. 150.
Plate XXXVII.

153. CYLINDRO-CRUCIFORM. X 175 linear. — From Hya-

154. lonema mirabilis, Gray, British Museum. The

155. four forms indicated by the above numbers occur

156. abundantly on the membranes immediately sur-
rounding the thick coriaceous sheath which envelops
the spiral column that is projected from the base of
the sponge through its centre. All the imaginable
varieties of form between Figs. 153 and 156 are
found mixed together; and they appear to be
especially abundant around that part of the column
which is imbedded in the midst of the sponge.
The cylindrical form represented by Fig. 153, is of

OF THE SPONGIAD.E. 253

FIG.

rare occurrence, without a slight indication near the
middle, of the absent third and fourth rays of the
perfect cruciform spiculum.

157. SPICULATED CYLINDRO-CRUCIFORM. X 174 linear. —

From Hyalonema mirabilis, Gray, British Museum.
This spiculum is from the sheath of the same
sponge as those represented by Figs. 153 to 156.
The ordinary cruciform spiculum being converted
into an external defensive one by the projection of
a spicular ray from its centre.

158. ATTENUATO-STELLATE. X 660 linear. — Having the

radii gradually attenuated from the base to the
apex. Pac/iywatisma Johnstonia, Bowerbank,
affords a large and very excellent type of this form
of spiculum. The radii vary from three to seven
or eight, but five or six rays are the most common
numbers. Page 51.

159. CYLINDRO-STELLATE, from Pachymatisma Johnstonia,

Bowerbank. X 660 linear. — Having the radii of
nearly equal diameter throughout, and terminating
hemispherically. This form also occurs abundantly
in Teihia robtista, Bowerbank, MS. The sponge is
in the British Museum, and was brought from
Australia by Mr. S. Stutchbury. The form and
proportions of these spicula vary considerably ;
sometimes the distal terminations of the radii are
slightly inclined to be clavate, and at others there
is a gradual transition from simply stellate to sub-
sphero-stellate. The radii are also in some of the
larger specimens slightly inclined to attenuation.

160. CRASSATO - CYLINDRO - STELLATE. X 1060 linear. —

This spiculum is remarkable from its having the
radii twice as broad as they are thick, and their
distal terminations abruptly truncated. It occurs
intermixed with the more regular forms of cylindro-
stellate in Tethca robusta.

254 ANATOMY AND PHYSIOLOGY

FIG.

161. CLAVATED SUBSPHERO-STELLATE. X 1060 linear. —

The cylindrical radii having the distal terminations
more or less dilated, and the central basal sphere
not exceeding in diameter the length of one of the
radii. This form of spiculum is very abundant in
Tethea Ligalli, Bowerbank, MS., intermingled with
attenuato-cylindro-stellate spicula.

162. CLAVATED SPHERO-STELLATE. X 1060 linear. — The

cylindrical radii having the distal terminations
dilated, and the central basal sphere greater in its
diameter than the length of one of the rays. This
spiculum is abundant in the sarcode of the dermal
and interstitial membranes of Geodia Barretti,
Bowerbank, MS. It is very minute, the extreme
diameter varying from g^th to T^th of an inch.
Page 52.

— . ELONGO-ATTENUATO-STELLATK, from Tethea muricata,
Bowerbank, MS. X 1060 linear.— See Fig. 35,
Plate I, and corresponding description.

163. ARBORESCENT ELONGO-SUBSPHERO-STELLATE. X 106

linear. — (See Plate X.) Having the radii spring-
ing from a dilated and elongated common base of
about the dimensions of two subsphero-stellate
spicula, partially fused together.
This remarkable form occurs abundantly in Geodia
carinata, Bowerbank, MS., from the South Sea. The
nucleus, whence the radii proceed, is always more or
less elongated, but is not usually so much dilated as
in the specimen figured. The arborescent character
of the distal terminations of the radii is also very
variable.

164. SUBSPHERO-STELLATE. X 660 linear. — Having the

radii more or less acutely conical, and as long or
longer than the diameter of the central basal sphere:
from Tethea Ingalli, Bowerbank, MS. In this
sponge and in other species this form occasionally
presents a very gradual transition from the purely
stellate form to the full subsphero-stellate one, in

OF THE SPONGIADJ3. 255

FIG.

which the radii and the spherical centre are of
about equal length, while in the fully developed
sphero-stellate forms this graduation is never seen.
Pages 51, 52.

165. SPHERO-STELLATE. X 660 linear. — Having the radii

acutely conical and based on a. large central sphere
of greater diameter than the length of the radii.
Tethea rohusta, Bowerbank, MS., a new species
from Australia, in the British Museum, presents an
excellent type of this form of spiculum. As the
central nucleus appears, under favorable circum-
stances, we distinctly trace a central canal in each
, ray, passing from the centre of the sphere to near
the distal termination of each of the radii, as re-
presented in Fig. 167. These canals are not
usually apparent in the perfect spicula, probably in
consequence of the fluid being hermetically sealed
within the canals of the radii, but I could not de-
termine the presence of the fluid by polarized light.
Pages 51, 52.

166. SPHERO-STULLATE WITH CYLiNDRO-sueroLiATE RADII.

X 400 linear. — Having the cylindrical radii slightly
expanded and somewhat foliated at the distal ex-
tremities. This remarkable form was obtained by
washing some specimens of Oculina rosea from the
South Sea, and there is little doubt of its being
from an unknown species of Tethea. Page 52.

167. A SPHERO-STELLATE SPICULUM, exhibiting the central

canals in the radii. X 660 linear. Page 52.

168.PiLEATED CYLINURO-STELLATE. X 660 linear. —

169. Having several recurved spines uniting and forming

170. a pileus at the apex of the ray, shaped like that of

171. a young mushroom. These singularly variable
spicula are abundant in Spongitta plumosa, Carter.
They are remarkable as affording a series of transi-
tional forms from a single straight spiculum to the
regular multiradiate stellate one. Fig. 168 repre-

256 ANATOMY AND PHYSIOLOGY

FIG.

sents, about the first stage of variation from the
simple elongate spinous spiculum, a few rather
strongly produced cylindrical spines appearing near
the middle of the shaft. In Fig. 169, two of these
spines are considerably more elongated than those
in Fig. 168, and the shaft is not so long as in that
figure. In Fig. 170 the axial shaft is still more
curtailed in its proportions, and the central radii
are further elongated and increased in number;
and in Fig. 171 we find the axial spiculum scarcely
distinguishable from the lateral rays. When the
radii projected are few in number, they are usually
at right angles to the axial spiculum. ; but when
they are produced in greater numbers, they are
projected at various angles, and the axial spiculum
can scarcely be detected. In spicula having numer-
ous radii, they frequently unite at their bases, and
produce their extreme variation of form, a sub-
sphero-stellate spiculum. No two of these singular
spicula are alike, and they present every imaginable
variation in the mode of their development. In
their origin from an axial spiculum, and in their
tendency to the projection of secondary radii at
right angles to that axis, these spicula form a con-
necting link between the simple multiradiate forms
and the more complicated ones belonging to the
compound stellate spicula.

172. EXTER-SPINULATED ARCUATE. X 1250 linear. — From

a small, massive sponge from the Bahamas, pre-
sented to me by my friend Mr. McAndrew. They
are very abundantly dispersed over all parts of the
interstitial membranes, are uniform in size, and
vary to some extent in the degree of spiculation.

173. SUBSPINULATO-ARCUATE. 260 linear. — Abundantly

dispersed on the interstitial membranes of a new
species of sponge from Freernantle, Western Aus-
tralia ; sent to me by my friend Mr. Geo. Clifton.

OJt1 THE SPONGIAD^E. 257

COMPOUND STELLATE SPICULA.
FIG.

174. ATTENUATED RECTANGULATED HEXRADIATE. X 90

linear. — From Euplectella aspergillum, Owen. A
fully developed spiculum. Page 52.

175. ATTENUATED RECTANGULATED HEXRADIATE. X 90

linear. — From the same sponge as Fig. 174. In an
early stage of development, exhibiting only the
primary or axial radii. Page 52.

[176. Progressive degrees of development of the secondary
| 177. radii of the same form of spiculum represented by
[178. Fig. 174. X 90 linear. Page 52.

179. The same spiculum as Fig. 175, with one secondary

ray fully developed. X 90 linear. Page 52.

180. The same spiculum as Fig. 175, having two secondary

rays forming a right angle with each other, fully
developed. X 90 linear. Page 53.

181. The same spiculum as Fig. 175, with two secondary

rays developed in opposite directions. X 90
linear. Page 53.

182. The same spiculum as Fig. 175, with three secondary

rays forming two right angles with each other.
X 90 linear. Page 53.

183. The same form of spiculum as Fig. 174, with the

whole of the secondary radii fully developed, bat
with one only of the axial radii produced. X 90
linear. Page 53.

184. SLENDER ATTENUATED RECTANGULATED HEXRADIATE.

From Euplectella aspergillum, Owen. X 90 linear.
Page 54.

185. CYLINDRO-RECTANGULATED HEXRADIATE, APICALLY

SPIN ED. From a specimen of Alcyoncellum, Quoy
et Gaimard, in the Museum of the Jardin des
Plantes, Paris. X 130 linear. Page 54.

17

258 ANATOMY AND PHYSIOLOGY

FIG.

186. One of the radii of the spiculum represented by

Fig. 185, exhibiting the spination of the apices.
X 400 linear.

187. Part of the axial shaft of a cylindro-rectangulated

hexradiate spiculum, exhibiting the parts from
which the radii would be produced, from the
Alcyoncellum in the Museum of the Jardin des
Plantes, Paris. X 400 linear. Page 54.

188. BIFURCATED RECTANGULATED HEXRADIATE STELLATE.

From the same Alcyoncellum as Fig. 187, in the
Museum of the Jardin des Plantes, Paris. X 1060
linear. — It is minute and slender, and the bifur-
cating rays are irregular, often tortuous, and are
frequently not produced on one or two of the pri-
mary radii. These indecisive characters, common
to all the specimens of this form that I have seen,
combined with the elongate characters of the radii,
seem strongly to mark this spiculum as the con-
necting link between the simple hexradiate and
the compound stellate forms of spicula. Page 55.

189. TRIFURCATED ATTENUATO-HEXRADIATE. From

tetta aspergillum, Owen, having the ray nearest the
eye broken off at its base. X 1060 linear. — The
central radii consist of six rectangulated primary
rays of equal length, each of which terminates in
three equidistant secondary attenuating rays, which
are projected from the apices of the primary ones
at an angle of about 45 degrees to the common
basal, or primary ray.
These spicula occur in abundance in Euplectella

asperc/ittum, Owen, and in Dactylocalyx pumicea,

Stutchbury. Page 55.

190. SPINULO-TRIFURCATED HEXRADIATE STELLATE. From

Dactylocalyx pumicea, Stutchbury, a perfect spicu-
lum. X 1060 linear. Page 55.

OF THE SPONGIAD^E. 259

PIG.

191. SPINULO-QUADRIFURCATE HEXRADIATE STELLATE.

X 1060. — A rectangulated hexradiate spiculum,
having each primary ray terminating in four nearly
equidistant cylindro-spinulate secondary radii.

These spicula occur abundantly in a beautiful and
unique specimen of a cup-shaped siliceo-fibrous
sponge formerly in the cabinet of my friend Mr.
Thomas Ingall, now in the British Museum. The
remains of the sarcode are crowded with them in a
perfect state of preservation. The specimen repre-
sented by Fig. 2 has had three of its primary radii
broken off near their common base, thus enabling us
to see distinctly the structure of this curious and
beautiful form of spiculum. Page 55.

192. SPINULO - MULTIFURCATE HEXRADIATE STELLATE.

X 660 linear. — This spiculum forms a connecting
link between the spinulo-quadrifurcate hexradiate
stellate form and the floricomo-stellate one. A
careful examination of the specimen presents indi-
cations of there having been as many as eight
secondary radii at the termination of the primary
ray which exhibits the greatest number of secondary
ones in the figure, and it is probable that this was
the full complement of those parts. Sponge un-
known. Page 55.

193. FLORICOMO - HEXRADIATE. — From Euplectella asper-

ff ilium ^ Owen, in the cabinet of Mr. Hugh Cuming,
showing four out of the six primary radii, and the
mode of the attachment of the secondary ones to
their distal terminations. X 660 linear. Page 55.

194. FLORICOMO-HEXRADIATE. — From the same sponge as

Fig. 193, exhibiting a front view of the congre-
gated expanded apices of one of the groups of the
secondary radii, and the contour of a perfect spicu-
lum. X 660 linear. Page 55.

260 ANATOMY AND PHYSIOLOGY

FIG.

195. CORONATO-HEXRADIATE STELLATE. From a Species

of Alcyoncellum in the Museum of the Jardin des
Plantes, Paris. X 1060 linear. — The central
radii consist of six rectangulated primary rays of
equal length, each terminating in a discoid expan-
sion, the margin of which is furnished with numer-
ous curved petaloid radii.

196. POCILIATED HEXRADIATE STELLATE. X 1060 linear.

The central radii consist of six rectangulated pri-
mary rays of equal length, each terminating in a
concavo-convex disc or cup, the convex surface
being outward.

I found this extremely minute form entangled in
the tissues of a specimen of Halichondria incrusfans,
dredged up by my friend Mr. McAndrew at the
Orkney Islands, and it is probably from one of the
small species of Alcyoncellum that are found in the
North Sea.

197. DENTATO- CYLINDRO- HEXRADIATE. X 660 linear.

(See Plate X.) — From a unique and very beautiful
branching sponge from Nichol Bay, Australia, sent
to me by my friend, Mr. Geo. Clifton, of Free-
mantle. The dentation of the radii of these spicula
varies considerably in form and size ; the number
of teeth at the apices of the rays is usually two or
three, occasionally four, and very rarely five. The
spicula are nearly uniform in size and are ex-
tremely abundant in all parts of the interstitial
membranes.

198. ATTENUATO-RECTANGULATED TRIRADIATE : APICALLY

SPINED. X 90 linear. — This form is not, as it
might be hastily surmised, the triradiate stage of
development of a hexradiate spiculum. It is
larger in every respect than the slender variety of
the hexradiate form, and less stout, but much
longer than the stout variety of the hexradiate

OF THE SPONGIAD.E. 261

FIG.

form previously described ; and although inter-
mingled with them and the other forms of
spicula in Euplectetta aspergittum, Owen, it is
always readily to be distinguished by an expe-
rienced observer.

The spines are small but thickly dispersed over
the apices of the radii for a short way down the shaft,
and occasionally the apices of the radii are more or
less clavate.

— . CYLINDRO-RECTANGULATED TRIRADIATE. — This form
of spiculum is abundant in Dactylocalyx pumicea,
Stutchbury. The basal axial ray is often very
much elongated. The radii are also incipiently
spined, and their apices are more or less spinulate
or clavate. The form of this spiculum is precisely
that of Fig. 198, excepting that the radii are
cylindrical instead of attenuated.

199. SPICULATED BITERNATE. X 90 linear. — I found

several of these spicula in the dust shaken from the
siliceo-fibrous massive sponge Farrea occa, Bower-
bank, MS., at the base of my friend Dr. A. Farre's
specimen of Euplectella cucumer, Owen, and I have
no doubt of their belonging to the sarcode of the
sponge at its base. They appear to vary greatly
in the amount of their development. In Fig. 199
the biternate spicula are simple, and it is spicu-
lated at one end only. Some of them were similar
to Fig. 199, but were spiculated at both ends.

200. FURCATED SPICULATED BITERNATE. X 130 linear. —

From Farrea occa, Bowerbank, MS. These spicula
are intermixed with those represented by Fig. 199.
They vary considerably in size, and in the number
of the rays which are furcated.

262 ANATOMY AND PHYSIOLOGY

SPICULA OF THE OVARIES AND GEMMULES.

1ST. SPICULA ELONGATE, DISPOSED AT RIGHT ANGLES TO
LINES RADIATING FROM THE CENTRE OF THE GEM-
MULE TO ITS SURFACE.

Fm.

1 201. ACERATE. X 30 linear. — This form occurs abun-
I 202. dantly in the envelope of the ovary of Spongilla
Carteri, Bowerbank, from the water-tanks of
Bombay; and in Sp. Brownii, Bowerbank, from
the River Amazon. In both these species the
spicula of the ovaries agree in form with those of
their respective skeletons, but are not more than
half their size. Eig. 201, a spiculum of the enve-
lope of the ovary of Spongilla Carteri. Fig. 202,
a spiculum of the envelope of the ovary of Spongilla
Brownii. Page 58.

O

203. SUBARCUATE ACERATE : ENTIRELY SPINED. X 660

linear. — The envelope of the ovary of Spongilla
lacustris, Johnston, abounds in this form. The
length and mode of spination of these spicula are
nearly the same in all of them, but the amount of
curvature varies from almost straight to nearly a
semicircle, as represented by Fig. 203 ; and in one
case the terminations of the spiculum have crossed
each other, forming a loop. In some sponges the
spicula of the ovaries agree in form with those of
the dermal membrane, but this is not the case in
the present instance, those of the membrane being
slender fusiformi-acerate. Pages 38, 58, 137.

204. FUSIFORMI-ACERATE : ENTIRELY SPINED, SPINE CYLIN-
DRICAL. X 660 linear. — These spicula are long,
slender, and very slightly curved; they are dis-
persed abundantly in the envelope of the ovary
of Spongilla Batei, Bowerbank, from the River
Amazon.

OF THE SPONGIAD^E. 263

FIG.

The spination of the spiculum is very remarkable ;
those near the middle of the shaft are frequently of a
length equal to half or two-thirds the greatest
diameter of the spiculum on which they are based.
They are of the same diameter from the base to the
apex, and terminate as abruptly as if they had been
truncated. Page 38.

205. ACERATE : ENTIRELY SPINED, SPINES CONICAL. X

060 linear. — This form of spiculum occurs in the
envelope of the ovary of /Sponyi/la cinerea, Carter.
It is very abundant and somewhat minute, and re-
quires a linear power of about 600 to define it
accurately. The spines are very numerous, and
all of them appear to pass from the spiculum at
right angles to its axis. The largest of them is
about one-third the length of the greatest diameter
of the spiculum.

206. CYLINDRICAL : INCIPIENTLT SPINED. X 400 linear.

— This short stout form of spiculum occurs abund-
antly in the envelope of Sponyilla yregaria, Bower-
bank, from the River Amazon. It is usually with-
out spines, but occasionally a few incipient . ones
are dispersed over the shaft.

207. CYLINDRICAL : ENTIRELY AND RECURVEDLY SPINOUS.

X 400 linear. — This large and beautiful form of spi-
culum is abundant in the envelope of the ovary of
Spongilla alba, Carter. It has a considerable
amount of curvature, and the spination is remark-
ably bold and striking. Very few of the spines
issue from the shaft at right angles to its axis, and
these are alwavs near its middle ; the remainder of

9

the spines are all curved from the apices of the
spiculum towards the middle of the shaft. The
spines are congregated in considerable numbers at
each termination of the spiculum, and are larger
and more curved there than on any other part of
the shaft.

264 ANATOMY AND PHYSIOLOGY

FIG.

— . CYLINDRICAL : ENTIRELY SPINED ; SPINES OF THE
MIDDLE CYLINDRICAL, THOSE OF THE TERMINATIONS
CONICAL AND RECURVED. — These spicula might
readily be mistaken by a hasty observer for those
of Spongilla alba, but a closer observation exhibits
essential differences in their mode of spination.
They are very numerous in the envelope of the
ovary of Spongilla cinerea, Carter, from the water-
tanks of Bombay. They are so nearly of the same
form as those represented by Fig. 207, as to render
it unnecessary to figure them. Page 59.

2ND. SPICULA DISPOSED IN LINES RADIATING FROM THE

CENTRE TO THE CIRCUMFERENCE OF THE OVARY.

Birotulate and Boletiform Spicula.

208. ADULT RECURVO-DENTATE BIROTULATE SPICULUM.

Shaft entirely spined, from the ovary of Spongilla
plumosa, Carter. X 660 linear. Pages 59 —
61.

209. A view of the inner surface of one of the rotulae of

the spiculum represented by Fig. 208, showing the
amount and irregularity of the dentation of its
margin. X 660 linear.

210. First stage of development of a birotulate spiculum

from :the ovary of Spongillaplumosa, Carter. X 660
linear. Page 61.

211. Second stage of development of a birotulate spiculum

from the ovary of Spongillaplumosa, Carter. X 660
linear. Page 61.

212. Third stage of develepment of a birotulate spiculum

from the ovary of Spongillaplumosa, Carter. X 660
linear. Page 61.

OF THE SPONGIAD^E. 265

FIG.

213. BlROTULATE, MARGINS OF THE ROTUL^E ENTIRE.

From Spongilla gregarea, Bowerbank. A side
view of an averaged-sized specimen. X 1100
linear. Page 137.

214. A view of the external surface of one of the rotulae of

the same form of spiculum as that represented by
Fig. 213. X 1100 linear. Page 137.

215. A young imperfectly developed spiculum of the same

description as represented by Fig. 213. X 1100
linear. Page 137.

216. A spiculum of the same description as represented

by Fig. 213, developed to a greater extent than
usual. X 660 linear. Page 137.

217. BlROTULATE, ROTUL^E IRREGULARLY AND DEEPLY

DENTATE. — From Spongilla fluviatilis, Johnston.
X 660 linear. Page 136.

218. A view of the external surface of one of the rotulse of
the same description of spiculum represented by
Fig. 217. X 660 linear. Page 136.

219. BlROTULATE: ROTUL^ IRREGULARLY AND DEEPLY
DENTATE, SHAFT MEDIALLY SPINED. X 660

linear. — This form occurs in the ovaries of Spon-
gilla Meyeni, Carter, from the water-tanks of
Bombay. It is the largest spiculum of that form
that I have yet seen. It differs from the congene-
rous form in Spongilla fluviatilis, inasmuch as the
spination of the shaft in Sp. Meyeni is the rule,
while in Sp. fluviatilis it is a rare exception. Pages
59, 137.

220. MULTIHAMATE BIROTULATE. X 660 linear. — This
singular form of spiculum is from the outer portion
of the ovaries of Spongilla recurvata, Bowerbank,
from the river Amazon.

The external surfaces of the rotulas are smooth,
very convex, and in many cases almost hemispherical ;
so that the points of the curved spines are in the di-
rection of lines parallel to the shaft of the spiculum,

266 ANATOMY AND PHYSIOLOGY

FIG.

and the rotulse are cleft almost to the point of union
with the shaft. The number of the curved spines
vary ; in one rotula there were as many as ten, but
the usual number is five or six. An average-

o

sized specimen measured ^th of an inch long ;
diameter of the rotulre, -^oih of an inch ; and dia-
meter of the shaft, ^8th of an inch.

(221. INEQUI-BIROTULATE. X 660 linear. — This spiculum
(222. exhibits a gradual transition from the fully de-
veloped birotulate to the completely boletiform
tribe of spicula: It occurs in Spongilla paulula,
Bowerbank, from the River Amazon. It is a stout
fully developed form, and the whole of them ex-
hibited, as nearly as possible, the same proportions.
From both terminations of the shaft a number of
minute radial canals, represented in Fig. 222, pass
from the centre to the circumference of the rotulae,
and in one of the large ones I counted twenty
radial canals. The rotula3 are flat, or very slightly
convex outward near the centre, and the margins
are perfectly entire. Pages 60, 61, and 137.

223. BOLETIFORM. X 660 linear. — The form of this
spiculum is very like that of the common edible
mushroom when fully grown. The large discal
end is convex externally, and has the margin entire.
The shaft is nearly of the same diameter through-
out its length, and occasionally it has one or two
large spines projected from it, near the middle and
at right angles to its axis.

The small end is more or less lentiform, but it is
frequently very irregular both in size and shape.
From the ovary of Sponyilla reticidata, Bowerbank,
River Amazon. Pages 60, 137.

/224. BOLETIFORM : SLENDER. X 660 linear. — This grace-

225. ful and elegant form of spiculum occurs at the inner

surface of the crust of the ovary of Sporty-ilia re-

curvata, Bowerbank, from the River Amazon. The

OF THE SPONGIAD^E. 267

FIG.

shaft is exceedingly slender, measuring at the
middle ^o^h of an inch in diameter. The large
discal end of the spiculmn is slightly convex ex-
ternally, has the margin perfectly entire, and
is ~th of an inch in diameter. The small lenti-
form end measured ^th of an inch in diameter,
and the total length of the spiculum is ~th of an
inch. Fig. 225 represents the inner surface of the
rotula. Pages 60, 137.

| 226. UMBONATO-SCUTULATE. X 660 linear.- -This spicu-
|227. him is found immediately beneath the outer mem-
brane of the ovary of Spongilla Broicnii, Bowerbank,
from the River Amazon. The form is truly that
of a little shield, the lower surface being concave,
while the upper one has a corresponding degree of
convexity, and the umbo projects from its centre in
the shape of a small cone. The diameter of an
average-sized one is ^th of an inch, and the
height very nearly equalled the diameter. Fig.
227 represents a side view of the spiculum show-
ing the length and form of the umbo. Page 60.

NEW FORMS OF SP1CULA FOUND SINCE THE PRECEDING ONES
WERE DESCRIBED AND FIGURED.

228. BISPINULATE. X 175 linear. — From Halicnemia

patera, Bowerbank. Page 15.

229. TRISPINULATE. X 175 linear. — From Halicnemia

patera, Bowerbank. Page 15.

230. The normal form of spinulate spiculum from the same

sponge as the spicula represented by Figs. 228 and
229." X 175 linear. Page 15.

f231. Undeveloped forms of spinulate, bispinulate, and
232. trispinulate, from the same sponge as the three pre-
233, ceding figures. X 175 linear. Page 15.
234. SPICULATED INEQUI-ANGULATED TRIRADIATE, with
cylindrical entirely spined radii. X 308 linear. —
From Dictyocylindrus Vickersii, Bowerbank, MS.

268 ANATOMY AND PHYSIOLOGY

FIG.

From the West Indies ? This spiculum is an ex-
ternal defensive one. The triradiate rays are im-
bedded immediately beneath the dermal membrane,
and the spicular ray is projected through it at right
angles to its plane ; they are very numerous.

235. SPICULATED ATTENUATO-EQUIANGULAR TRIRADIATE :

VERTICILLATELY spiNED. X 660 linear. — From an
un described sponge. Freemantle, Western Aus-
tralia. I have not seen the specimen whence this
spiculum is derived, but,, reasoning from our
knowledge of the form and situation of the spicu-
lum represented by Fig. 234, there can be little
doubt of its being an external defensive one.

236. SPICULATED CYLINDRO-EQUIANGULAR VERTICILLATELY

SPINED. X 660 linear. Freemantle, Western
Australia. From the same slide of Sponge spicula
in which the form represented by 235 was found.
There can be little doubt of its being an external
defensive organ.

237. INEQUI-FURCATO-TRIRADIATE. X 183 linear. — These

spicula are from a new species of calcareous
sponge, probably a Grantia. They were sent to
me mounted in Canada balsam by my friend Mr.
George Clifton, of Freemantle, Australia. They
occur loosely fasciculated, and their mode of dis-
position is probably on the surface of the sponge.
They differ considerably from each other in length
and in the width apart of the prongs of the fork,
but they all have them unequal in length. It is
probably an auxiliary skeleton and external defen-
sive spiculum.

238 and 239. ATTENUATO-CYLINDRICAL VERTICILLATELY
SPINED. X 183 linear. — From Hymeraplda ver-
ticillata, Bowerbank. These spicula are dispersed
in abundance on the interstitial and dermal mem-
branes of the sponge. In the young state the
spicular are long, slender, and perfectly smooth ;

OF THE SPONGIAD^E. 269

FIG.

in the course of their further development they
assume a monilliform appearance, as represented
by Fig. 239, and in their adult state are verticil-
lately spined, as represented by Fig. 238.

240. INFLATO-ACERATE, with incissurate terminations.
X 660 linear. — From Hymerapliia verticillata,
Bowerbank. A terminal portion only of this spi-
culurn is represented by the figure, the incissurate
character being the only novelty in the form. The
incissuration varies in degree to a considerable ex-
tent in different spicula, in some cases being very
slightly produced, in others rather beyond that re-
presented by the figure. The rudiments of a third
ray are sometimes apparent. This form is an aux-
iliary skeleton spiculum. They are found thickly
clustered round the primary spicula of the skeleton.
They differ essentially from porrecto-ternate spicula
in having both ends cleft or radiate, which is never
the case in any of the ordinary ternate forms.

SPICULA, THE POSITIONS OF WHICH ARE UNKNOWN.
241. BlRECURVO-QUATERNATE, MEDIALLY SPINED. Sponge

unknown, X 660 linear. — Probably an internal
defensive spiculum.

242. SPINULATO-ENSIFORM, from a parasitical sponge from

Western Australia. X 130 linear. — I obtained
this singular form from a parasitical sponge from
Western Australia. This curious sponge, in the
formation of its skeleton, appears to have appro-
priated the spicula of every other kind of sponge
that came within its reach.

243. ACUATE : BASALLY RECTANGULATED. X 150 linear.

— 1 obtained this spiculum from the spongeous
matter scraped from the base of Oculina rosea,
by a dealer in the process of cleaning the coral.
It is not a malformation, as there are several

270 ANATOMY AND PHYSIOLOGY

FIG.

of them in the same slide, and they are all angu-
lated to the same extent. It is probably an inter-
nal defensive spiculum.

244, 245, 246. TUBERCULATED FUSIFORMI - CLYINDRI-
CAL. — The beautiful spiculum represented by Fig.

244, X 660 linear, is siliceous. It has been re-
peatedly found in the matter obtained by washing
the roots of Oculina rosea and other corals from
the South Sea, by my friends Messrs. Matthew
Marshall, Legg and Ingall, but the sponge, whence
it is most probably derived, has never yet been
determined. It is remarkable as being the only
well-defined and perfect siliceous spiculum that
has yet been observed to possess the short stout
tubercles that are so characteristic of its structure.
Fragments of two other spicula, possessing similar
characters, have been observed by me, and are re-
presented by Figs. 245 and 246. In the specimen
represented by Fig. 246, X 260 linear, the tuber-
cles are less in number, but are considerably more
produced, and their terminations are more abruptly
truncated. In the spiculum represented by Fig.

245, X 260 linear, they are still more widely dis-
tributed, are shorter and more inclined to be coni-
cal, so that there is little doubt that they have be-
longed to three distinct species of sponge. But in
all three of them there is one peculiarity, that of
the manner of the disposition of the tubercles on the
shafts of the spicula, where we observe them to be
disposed in more or less regular longitudinal lines,
and that the tubercles forming each line alternate
with those of the line next to them, so that they
assume the appearance of a spiral arrangement.
The close alliance in the structure of these spicula
would seem to indicate the existence of a peculiar
tribe of sponges, with which we are at present en-
tirely unacquainted.

OF THE SPONGIAD^. 271

ANATOMICAL STRUCTURE OF SP1CULA.

FIG.

247. Distal termination of a porrecto-ternate spiculum from

TetJtea cranium, with angular distortions from ex-
ternal pressure. X 260 linear. Page 6.

248. A portion of an adult spiculum from Spongilla

fluviatilis, charred to exhibit the thin membrane
of the central cavity of the spiculum. X 260
linear. Page 6.

249. A portion of an immature spiculum from Spongilla

lacustris, charred to exhibit the dense membrane
lining the large central cavity in the young spicu-
lum. X 260 linear.

250. A section at right angles to the axis of the upper

part of the shaft of a ternate spiculum from Geodia
Barretti, Bowerbank, MS., exhibiting the concen-
tric layers. X 260 linear. Page 6.

251. 252. Portions of charred spicula from the skeleton

fasciculi of Tethea cranium, exhibiting their hol-
low condition after incineration. X 90 linear.
Page 8.

253. A portion of a spiculum from Euplectella aspergillum,

Owen, slightly charred, exhibiting the concentric
layers of silex. X 90 linear. Page 11.

254. A portion of an adult spiculum from the skeleton of

Geodia McAndrewii, Bowerbank, MS., cracked by
the application of cold water while in a heated
state. X 90 linear. Page 9.

MEMBRANOUS TISSUES.

255. FIBRO-MEMBRANOUS TISSUE. Containing a single layer

of parallel fibres on a portion of the membrane
from an excurrent canal of one of the common
honeycomb sponges of commerce. X 660 linear.
Pages 67, 99, and 100.

272 ANATOMY AND PHYSIOLOGY

FIG.

256. FIBRO-MEMBRANOUS TISSUE. From the dermal mem-

brane of a Stematumenia. X 183 linear. Pages
100, 211.

257. FIBRO-MEMBRANOUS TISSUE. In which the layers of

fibre cross each other at about ridit angles. From
Alcyoncellum robusta, Bowerbank. X 660 linear.
Page 100.

25S. FIBRO-MEMBRANOUS TISSUE. In which the layers of
fibre cross each other at various acute angles.
From Alcyoncellum robusta, Bowerbank. X 308
linear. Page 100.

FIBROUS STRUCTURES.

PRIMITIVE FIBROUS TISSUE.

259. PRIMITIVE FIBROUS STRUCTURES. Dispersed on the

inner surface of a portion of the dermal membrane
of a young Stematumenia; a a, cells in situ,
which have each produced a fibre. X 660 linear.
Page 70.

260. DETACHED SPECIMENS OF PRIMITIVE FIBROUS TISSUE.

In progressive stages of development. X 660
linear. Page 70.

KERATOSE FIBROUS TISSUE.

26 1 . SOLID KERATOSE FIBRE. From a cup-shaped specimen

of the best Turkey sponge of commerce, in the
condition in which it came from the sea. X 175
linear. Page 73.

262. SPICULATED KERATOSE FIBRE. From Chalina oculata,

Bowerbank. X 175 linear. Pages 74, 208.

OF THE SPONGIAD.E. 273

FIG.

263. SPICULATED KERATOSE FIBRE. From Chalina Mon-
tagui, Bowerbank, a young fibre in course of
development (a) the apical spiculum. X 175
linear. Pages 74 and 108.

264. MULTISPICULATED KERATOSE FIBRE. From Des-

macidon (eyagropila, Bowerbank. X 108 linear.
Page 75.

265. INEQUI-SPICULATED KERATOSE FIBRE. From Ea-

phyrus Griffit/tm, Bowerbank. X 175 linear. Pages
75 and 201.

266. SIMPLE FISTULOSE KERATOSE FIBRE. From Sjwnyia

jistdaris, Lamarck. X 108 linear. Pages 76 and
209.

267. COMPOUND FISTULOSE KERATOSE FIBRE. From the

skeleton-fibres of Auliskia, Bowerbank, exhibiting
the secondary canals radiating from the primary
ones. X 300 linear. Pages 77 and 210.

268. COMPOUND FISTULOSE KERATOSE FIBRES. From

Auliakia, Bowerbank, exhibiting the general cha-
racter of the fibre. X 100 linear. Pages 77 and
210.

269. REGULAR ARENATED KERATOSE FIBRE. From one of

the Bahama sponges of commerce. X 175 linear.
Page 77.

270. IRREGULAR ARENATED KERATOSE FIBRE. From Dy-

sided fragilis, Johnston, having the siliceous grains
very abundantly packed in its substance. X 10s
linear. Pages 78 and 211.

271. IRREGULAR ARENATED KERATOSE FIBRE. From Dy-

sldea fragilis, Johnston, exhibiting its general cha-
racter in situ. X 108 linear. Pages 78 and 211.

"272. IRREGULAR ARENATED KERATOSE FIBRE,, showing how
the young fibre picks up the grain of sand and
surrounds it with keratode. X 108 linear. Pages
63, 78, and 211.

273. HETRO-SPICULATED KERATOSE FIBRE. From Dip-
lodemiavesicula,Rowei'bank. X 175 linear. Pages
74 and 202. (See Plate XIV.)

18

274, ANATOMY AND PHYSIOLOGY
FIG.

274. SMOOTH SOLID SILICEOUS FIBRE. From McAn-
dreivsia, Gray. X 175 linear. Pages 13, 79,
and 204.

275. TUBERCULATED SOLID SILICEOUS FIBRE. From Dactylo-

calyx pumice a, Stutchbury. X 108 linear. Pages
79 and 204.

276. TUBERCULATED SOLID SILICEOUS FIBRE, very promi-

nently tuberculated. From Dactylocalyx Prattii,
Bowerbank, MS. X 175 linear. Pages 80 and
204.

277. SIMPLE FISTULOSE SILICEOUS FIBRE, SPINULATED.

From Farrea occa, Bowerbank, MS. X 108
linear. Pages 13, 80, and 204.

PREHENSILE FIBRE.
278. ClDARATE PREHENSILE FISTULOSE SILICEOUS FIBRE.

From a parasitical siliceo-fibrous sponge from the
south sea ; showing the position of the prehensile
organs at the base of the sponge. X 83 linear.

Page 80.

FIBRILATED FIBRE.

279. FIBRILATED SPONGE FIBRE. From the skeleton of one

of the sponges of commerce. X 308 linear.
Page 73.

280. FIBRILATED SPONGE FIBRE. From one of the rigid

Australian sponges. X 175 linear. Page 73.

CELLULAR TISSUES.

•

281. A group of cells on a piece of an interstitial membrane

from Ecionemia acervus, Bowerbank, MS. X 660
linear. Pages 81 and 88.

2Q2. Cells on a portion of the interstitial membrane of
Halichondria nigricans, Bowerbank. X 308 linear.
Pages 82 and 88.

OF THE SPONGIAD7K. 275

FIG.

283. Detached nucleated cells, from a new species of

sponge, from Freemantle, Western Australia.
X 308 linear.

284. A view of the upper stratum of cells in one of the Ovaria

of SpongiUa Carteri, Bowerbank. X 308 linear.
For cellular tissue in Grantia see Figs. 312 and
314, Plate XXI, Pages 82 and 139.

SARCODE.

285. Represents a small piece of an interstitial membrane

from the honeycomb sponge of commerce in the
condition in which it came from the sea, exhibiting
the sarcode in situ and the imbedded semi-digested
molecules of nutriment. X 660 linear. Page 88.

INTERNAL AND EXTERNAL DEFENCES.

286. A small portion of a longitudinal section through the

cloaca of a specimen of Grantia tessellata, Bower-
bank, MS., showing the positions of the internal
defensive spicula, and their curvature towards the
mouth of the cloaca. X 108 linear. Page 29.

287. A portion of a thin section at right angles to the surface

of a specimen of Chalina seriata, Bowerbank, illus-
trating the mode of external defence by the pro-
longation of the radial lines of the skeleton. X 108
linear. Page 24.

288. A small portion of the kerato-fibrous skeleton of an

i

Australian sponge, showing the attenuato-acuate
entirely spined internal defensive spicula in situ
dispersed on the skeleton fibre. X 108 linear.
Page 31.

289. Verticillately spined internal defensive spicula dis-

persed on keratose fibres of the skeleton, from a
West Indian sponge. X 175 linear. Pages 23
and 125.

276 ANATOMY AND PHYSIOLOGY

FIG.

290. Verticillately spinecl internal defensive spicula from a

keratose sponge, from the West Indies. Congre-
gated in fasciculi. X 175 linear. Pages 3 land
125.

291 . A small portion of Hymeniacidon Cliftoni, Bowerbank,

MS., exhibiting the membranous tissues of the
sponge enveloping the fibres of a Fucus; the defen-
sive spicula over the fibre being erect, whilst those
on the adjoining membrane are recumbent. X 1 08
linear : — a, one of the attenuate-cylindrical internal
defensive spicula. X 260 linear; b, a small portion
of the surface of the Fucus showing its cellular
structure. X 400 linear. Pages 31 and 125.

292. A portion of the reticulated specimen of the sponge

with the radiating fasciculi of spinulo-quaternate
internal defensive spicula in situ. X 108 linear.
See also Pig. 76, Plate III. Pages 23, 33, and 122.

293. A portion of the reticulated skeleton of Hymedesmia

Joknsoni, Bowerbank, MS., from Madeira, the fibres
armed with trenchant contort bihamate spicula.
X 50 linear. One of the trenchant contort biha-
mate spicula, showing the cylindrical form at the
curves of the hook and the middle of the shaft, and
the trenchant edges of the rest of the inner sur-
faces of the spiculum, X 400 linear, is represented
by Pig. 112, Plate V. Pages 35 and 127.

294. A portion of the skeleton of Hyalonema mirabilis,

Gray, showing the mode of disposition of the mul-
tihamate birotulate and spiculated cruciform spicula
in the body of the sponge. In the collection at
the British Museum. X 50 linear. One of the
multihamate birotulate, X 175 linear, is repre-
sented by Fig. 60, Plate III, and Fig. 294, Plate
XVIII. Pages 37 and 127.

295. Represents a spiculated cruciform spiculum from

the same sponge, to show the relative proportions
of the two forms of defensive spicula. X 175
linear. Pages 37 and 127.

OF THE SPONGIAD.E. 277

FIG.

296. Represents a small portion of the inner surface of the

dermal membrane of Hymedesmia Zetlandica,
Bowerbank, showing the fasciculation of the simple
bihamate spicula, the eqm'-anchorate ones dispersed
singly on the membrane and the large attenuato-
acuate entirely spined defensive ones in situ. X 308
linear. Pages 44 and 190.

297. A circular group of inequi-anchorate spicula, situated

on one of the interstitial membranes of Hymenia-
cidon lingua, Bowerbank. X 308 linear. See
also Figs. 138, 147, &c.3 Plate VI. Page 49.

298. A small portion of the dermal membrane from Die-

tyocylindrus stuposus, Bowerbank, exhibiting the
number and position of the minute sphero-stellate
defensive spicula with which it is armed. X 308
linear. Page 109.

INTERMARGINAL CAVITIES.

299. A section at right angles to the surface of a branch

of Isodictya simulans, Bowerbank, exhibiting the
form and position of the intermarginal cavities.
X 108 linear. Page 101.

300. A section ofjffalincfrondriapamcea, Johnston, showing

the intermarginal cavities at a, immediately beneath
the dermal surface. XlOSlinear. Pages lOOand 195.

301. View of a small portion of the inner surface of the

dermal crust of Geodia Barretti, Bowerbank, MS.,
with two of the valvular membranes of the proxi-
mal ends of the intermarginal cavities : — a, valve
closed ; b, a valve partly open ; c, c, the radii of
the patento-ternate spicula, imbedded in the tis-
sues, and forming the areas for the support of the
valvular terminations of the intermarginal cavities.
X 50 linear. — Longitudinal sections of two of the
intermarginal cavities are shown at a, a, Pig. 354.
Plate XVIII.

Dermal membrane and inhalent pores, pages
111 and 173.

278 ANATOMY AND PHYSIOLOGY

FIG.

302. Two groups of inhalent pores in the dermal mem-

brane, situated immediately above the distal ends
of the intermarginal cavities of Geodia Barretti.
X83 linear. Page 171.

303. A portion of the dermal surface of If afic/tondria pani-

cea, Johnston, showing the multispicular network
for the support of the dermal membrane and the
open pores in the areas. X 108 linear. Pages
108 and 195.

304. A small portion of the dermal membrane of Ti'thea

muricata, Bowerbank, MS., exhibiting the pores in
an open condition. X 108 linear. Pages 25 and
108.

305. A small portion of the same piece of membrane,

highly magnified, to show the positions of the
elongo-stellate defensive spicula on the external
surface of the dermal membrane. X 183 linear.
Pages 25 and 108.

306. Represents the inner surface of the clermis of Dactylo-

calyx Prattii, Bowerbank, MS., showing the manner
in which the apices of the radii of the ternate spicula
forming the inhalent porous areas, are spliced on
each other to allow of the expansion and contrac-
tion of the dermal surface. X 108 linear. Pages
18, 19 and 101.

307. Represents a portion of the dermal surface of an un-

described sponge from the East Indies, having
numerous depressed porous areas furnished with
stqmata-like protective organs, a, the protective
organ in a perfect condition ; 6, having the pro-
tective organ removed to exhibit the deeply
depressed porous area. X 50 linear.

308. A portion of the sponge represented of its natural

size, with two large oscula and numerous inhalent
areas.

309. A small portion of the single-scried dermal spicula r

network of Isodictya variant, Bowerbank. X
linear. Page 10s*.

OF THE SPONGIAD.E. 279

FIG.

310. A piece of reticulated kerato-fibrous tissue supporting

the dermal membrane of one of the species of the
common West Indian sponges of commerce.
X 108 linear. Pages 108, 109.

311. A small portion of the quadrilateral siliceo-fibrous

network of the dermis of Farrea occa, Bowerbank,
MS., showing the double series of entirely spined
spicular organs projected from its angles. X 108
linear. Page 104.

CILIA AND CILIARY ACTION.

312. A longitudinal section of the intermarginal cavities of

Grantia coiupressa, showing the cilia and their
basal cells in situ. X 500 linear. Pages 82, 105,
129, 130, and 163.

313. A view -of a small portion of the inner surface of

Grantia compressa, exhibiting the oscula open,
and the appearance presented at their orifices by
the cilia within in action. X 500 linear. Pages
105, 129, 130 and 163.

314. Detached cilia and tessellated cells from the interior

of the intermarginal cavities of Grantia coiupressa.
X 1250 linear. («) A cilium in repose. (&) One
in the position of action, (r) Detached cells.
Pages 82 and 129.

REPRODUCTIVE ORGANS.

315. A small piece of a fibre of the skeleton of one of the

common Bahama sponges of commerce, with nu-
merous ova imbedded in its surface. X 400
linear. Pages 81 and 134.

316. A small piece of the fibre represented by Fig. 315,

exhibiting the varieties in form and proportion of
the ova. X 1250 linear. Pages 81 and 13t.

280 ANATOMY AND PHYSIOLOGY

FIG.

317. An ovariumof Spongillajluviatilisw its natural state,

exhibiting the foramen. X S3 linear. Page
132.

318. A perfect skeleton of an ovarium of Spongilla fluma-

tilis, Johnston, prepared with nitric acid. X 183
linear. Pages 60 and 136.

319. View of a section, at right angles to the surface, of a

fragment of the skeleton of the ovarium of Spon-

gilla fuviatilis, prepared with nitric acid, exhibiting

the relative positions of the spicula in the skeleton.

(a) A spiculum detached from the same ovarium

X 308 linear. Pages 60 and 136.

320. A skeleton of an ovarium of Spongttla lacusfris, pre-

pared with nitric acid, exhibiting the spicula in
situ and the foramen. X 183 linear. Pages 58,
60 and 137.

321. Two of the reticulated cases of the ovaria of Spongilla

Brownii, Bowerbank : — a, an empty case ; b, a
case containing the skeleton of an ovarium. X 50
linear. Page 139.

3*22. A reticulated case of an ovarium of SpongiUa reticu-
lata, Bowerbank. X 175 linear. Page 138.

323. Skeleton of an ovarium of Spongilla reticulata,

Bowerbank, without its case, prepared with nitric
acid. X 175 linear. Page 138.

324. A perfect ovarium of Diplodemia vesicula, Bower-

bank, and a portion of a second one, showing the
interior and the thickness of its walls in its
natural state. X 83 linear. Pages 60 and 140.

325. An ovarium of GeodiaMcAndrcwii, Bowerbank, MS.,

in very nearly an adult state, showing the struc-
ture and position of the conical foramen for the
discharge of the ova, natural condition. X 183
linear. Page 142.

OF THE SPONGIAD.E. 281

FIG.

32G. A small portion of the surface of a fully-developed
ovarium of Geodia McAndrewii in its natural
state, showing the distal ends of the spicula flat
and angular, and firmly cemented together.
X 308 linear. Page 142.

327. Two ovaria of Geodia McAndrewii, (a) containing

about the maximum of ova, (b] after a great part
of the ova have been discharged. X 108 linear.
Pasre 141.

O

328. A portion of a section through nearly the centre of a

mature ovarium of Geodia McAndrewii, showing
the radiation of its spicula from near the centre to
its circumference. X 308 linear. Page 142.

329. A portion of a young ovarium of Geodia McAndrewii,

with the distal ends of its spicula acutely termi-
nated, and unconnected. X 308 linear. Page
142.

330. A mature ovarium of Pacliymatisma Jolmstonia,

Bowerbank, exhibiting the cuneiform spicula of the
foramen. X 308 linear. Page 143.

331. A young ovarium of Pacliymatisma Jolmstonia in

course of development. X 308 linear. Page
143.

332. A young ovarium of Pacliymatisma Jolmstonia in a

very early stage of development. X 308 linear.
Page 143.

333. An ovarium from a sponge from Madeira closely

allied to Pacltymatisma, exceedingly depressed and
much elongated. X 308 linear. Page 143.

334. A fragment of a similar ovarium to that represented

by Fig. 333, the fracture showing its extremely
thin condition. X 308 linear. Page 143.

335. A young ovarium of the same species as that repre-

sented by Fig. 333, in an early stage of develop-
ment. X 308 linear. Page 143.

28.2 ANATOMY AND PHYSIOLOGY

FIG.

336. A reticulated ovarium in situ, on the fragment of a

sponge from Madeira. X 108 linear. Page
144.

337. A portion of the reticulated structure from an ovarium

of the same description as represented by Fig. 336.
X 308 linear. Page 144.

338. An ovum in course of development into a young

sponge on the same membrane as that on which
the ovarium represented by Fig. 336 is seated.
X 108 linear. Page 144. '

339. A group of ova or gemmules in course of develop-

ment into young sponges, found, with many others,
on the inner surface of a fragment of a large Pecten
from Shetland. X 108 linear. Page 146.

340. A small portion of the skeleton of Jpkiteon jmnicea

in the Museum of the Jardin des Plantes, Paris, with
gemmules in situ. X 183 (Dactylocaliae, Stutch-
bury). Pages 146 and 204.

341. A gemmule detached from Iphiteonpanicea. X 660

linear. Page 204.

342. A gemmule extruded from near the base of a speci-

men of Tetkia lyncurium, on the distal extremity
of one of the skeleton fasciculi. X 50 linear.
Page 149.

343. Part of a group of internal gemmules in situ, on the

interstitial membranes of Tethea cranium : — a, one
of the larger and most completely organized gem-
mules ; b, one of the smaller and more simple
gemmules which always accompany the larger ones.
In Canada balsam. X 108 linear. Page 148.

31-4. One of the larger description of gemmules of Tethea
cranium, in its natural state, removed from the
membrane and viewed by direct light. X 25
linear. Page 148.

OF THE SPONGIADJ3. 283

ILLUSTRATIONS OF THE GENERA.
ORDER I. — Cakarea.

FIG.

345. GRANTIA. A longitudinal section of a portion of one

side of a specimen of Grantia ciliata, Johnston, ex-
hibiting the structure and mode of disposition of
the interstitial cells. X 108 linear. See also Fig.
312, PI. XXI, for the interstitial cells of G. com-
pressa. Pages '27, 119, and 163.

346. A group of two Grantias on a Zoophyte, natural size ;

«, G. ciliata, b, G. coiiipressa. Page 103.

547. LEUCOSOLENIA BOTRYOIDES, Bowcrbank. Two
branches exhibiting the simple fistulose structure
of the sponge. X 50 linear. Page 164.

348. A small group of the sponges L. botryoidcs, natural
size. Page 164.

349. — LEUCOGYPSIA GOSSEI, Bowcrbank. A section at
right angles to the surface, exhibiting the mass of
irregular interstitial structure. X 50 linear. Page
166.

350. A specimen of L. Gossei, natural size, exhibiting the
form and position of the oscula. Page 166.

351. — LEUCONIA ISIVEA, Eowerbank. A longitudinal sec-
tion of one of the mammiform portions, exhibiting
one of the great cloacal cavities of the sponge and
its internal defensive spicula. X 50 linear. Page
165.

352. An averaged-sized specimen of L. nivea, exhibiting
the lobular form of the cloacal portions of the
sponge and the position of the mouths of the
cloacae. Page 165.

284 ANATOMY AND PHYSIOLOGY

Order '2. — SILICEA.

Sub-order L.
FIG.

353. PACHYMATISMA JOHNSTONIA, BowerbanJc. A section

at right angles to the surface, exhibiting the irregu-
larity of the interstitial structures directly beneath
the dermal crust. X 50 linear. Page 172.

354. GUODIABARRETTI, Bowerbcmk, MS. A section at right

angles to the surface, exhibiting the radial disposi-
tion of the fasciculi of the skeleton, and a portion
of the dermal crust of the sponge. X 50 linear.
—a, interinarginal cavities ; b, the basal dia-
phragms of the interinarginal cavities ; c, imbedded
ovaria forming the dermal crust of the sponge ; <-/,
the large patento-ternate spicula, the heads of
which form the areas for the valvular bases of the
interinarginal cavities ; e, recnrvo-ternate defensive
and aggressive spicula within the summits of the
great intercellular spaces of the sponge ; f, portions
of the interstitial membranes of the sponge, crowded
with minute stellate spicula ; y, portions of the
secondary system of external defensive spicula.
Pages 122, 169 and 171.

355. ECIONEMIA ACERVUS, BowerbanJc, MS. A section at

right angles to the surface, exhibiting the radial
fasciculi of the peripheral system, with the ternate
apices of the spicula directly beneath the dermal
membrane. X 50 linear. Page 174.

356. ALCYONCELLUM ASPERGILLUIU, Qtioy et Gaimard

(Euplectella — Owen}. A portion of the surface of
the sponge, with its great inhalent areas ; a, the
primary longitudinal fasciculi ; b, the secondary
or transverse fasciculi. X 7 linear. Pas;e 177.

O

357. The oscular area of A. asperc/illum, with a marginal

boundary, and the congregated oscula within,
natural size. Page 177.

OF THE SPONGIAD.E. 285

FIG.

358. POLYMASTIA ROBUSTA, Bowerbank. A view of a small

portion of the side of one of the large cloacae, ex-
hibiting the structure and mode of disposition of
the longitudinal skeleton fasciculi. X 25 linear.
Page 178.

359. HALYPHYSEMA TUMANOWICZII, Bowerbank. A com-

plete sponge, based on the stem of a Zoophyte,
exhibiting the irregular longitudinal disposition
of the skeleton spicula. X 175 linear. Page
179.

300. CIOCALYPTA PENICILLUS, Bowerbank. Representing
a longitudinal section through the central axis of
one of the elongate cloacal portions of the sponge,
exhibiting the central column with the small
cylindrical pedicels or short fasciculi of closely
packed spicula, each terminating at the inner sur-
face of the dermis of the sponge, natural size. Page
181.

361. A section of the speciuien represented by Fig. 360,
at about the middle of the cloacal column, ex-
hibiting the mode of the radiation of the distal ends
of the small pedicels on the inner surface of the
dermis. X 25 linear. Page 131.

302. TETHEA CRANIUM, Lamarck. A portion of a thin sec-
tion at right angles to the surface, exhibiting the
upper portion of the radiating fasciculi ; their
terminations being projected beyond the dermal
surface of the sponge. X 50 linear. — a, porrecto-
ternate external defensive spicula ; b, the mode in
which they are supported by buttresses of spicula
beneath the surface of the sponge ; c, the recurvo-
ternate spicula. Pages 25, 124 and 183.

363. HALICNEMIA PATERA. A portion of a section at
right angles to the surface, exhibiting the mode of
disposition of the spicula of the skeleton. X 25
linear. Page 184.

286 ANATOMY AND PHYSIOLOGY

FIG.

364. A portion of the section represented by Fig. 363,

taken at a, X 108 linear. Pages 184 and 200.

365. DICTYOCYLINDRUS RUGOSUs, Bowerbank. Represents

a longitudinal section of half of a small branch, ex-
hibiting a portion of the axial column a, and the
peripheral system arranged in fasciculi, radiating
from it. X 50 linear. Pages 24 and 186.

366. A longitudinal section through the axial column of

Dictyocylindrus ramosus, showing the elongo-reticu-
late structure of the skeleton of the sponge. X 50
linear. Page 186.

367. PHAKELLIA VENTILABRUM, Bowerbank. A longitu-

dinal section of half of one of the primary radial
lines of skeleton structure, exhibiting the slender
secondary radiation of the skeleton. X 50 linear;
a, part of the axial column. Page 187.

368. MICROCIONA ATRASANGUINKA, Bowerbank. A single

mature pedestal of the skeleton, showing its struc-
ture and the proportions and positions of the ex-
ternal defensive spicula. X 175 linear. Pages 26
and 188.

869. A section at right angles to the surface of Microciona
astrasanguinea exhibiting the mode of the disposi-
tion of the columns of the skeleton and the dermal
surface at a. X 108 linen r. Pages 26 and 188.

370. HYMERAPHIA STKLLIFERA, Bowerbank. A section at
right .angles to the basal membrane, showing the
large bulbous skeleton spicula in situ, their apices
forming the external defences ; a, the stelliferous
internal defensive spicula elevated by a grain
of sand beneath the basal membrane. X 108
linear. Fig. 34, Plate T, represents one of this
form of spiculum. X 260 linear. Pages 27, 32,
325 and 189.

OF THE SPONGIAD^!, 287

FIG.

371. HYMEDESMIA ZETLANDICA, Bowerbank. Exhibiting

the disjoined fasciculi of the skeleton in situ.
X 108 linear. See also Fig. 296, Plate XVIII,
Page 190.

Sub- Order 2.

372. HYMENIACIDON CARUNCULA. Exhibiting the dispersed

condition of the skeleton spicula on the interstitial
membranes of the sponges. X 108. Page 192.

Sub- Order 3.

373. HALICHONDRIA INCRUSTAISS. Exhibiting a better

type of the skeleton structure of the genus than
Halichondria panicea. X 50 linear. See also
Figs. 300, 303, Plate XIX, for Halicliondria
panicea. Page 195.

374. HYALONEMA MIRABILIS, Gray. The figure represents

a portion of the spiral fasciculus of single, elongated
and very large spicula, forming the axial skeleton
of a columnar cloacal system ; surrounded by a

i/ ...

portion of its coriaceous envelop, exhibiting
numerous oscula on its surface ; natural size.
Copied from the figure in the ' Proceedings of the
Zoological Society of London, for 1857.' Pagel97.

375. A portion of the skeleton of Byalonema wirabilis,

Gray, showing the indefinite nature of the sepa-
rated elongated fasciculi of the skeleton. X 50
linear. Page 197.

)?>76. ISODICTYA NORMANI. Exhibiting the regular and
nearly rectangular structure of the network of the
skeleton of spicula. X 108.
Spowgilla. Agrees perfectly in the structure of
the skeleton with Isodicfya, but is distinguished from
that genus by the peculiarities of the reproductive
organs. Pages 197 and 199.

ANATOMY AND PHYSIOLOGY

Sub-Order &.

DESMACIDON.— See Fig. 264, Plate XIII.
RAPHYRUS.— See Fig. 265, Plate XIII.

Sub -Order 5.

FIG.

377. DIPLODEMIA VESICULA. A small portion of its com-
pound reticulate skeleton, exhibiting the inter-
mixture of the spiculo-reticulate skeleton with the
hetrospiculate fibrous one. X 108 linear. See
also Fig. 273, Plate XIV, for structure of hetro-
spiculate fibre. X 175 linear. And Fig. 324,
Plate XXIII, for the ovaria. X 83 linear. Page
202.

For 878 see page 289.

Sub- Order 6.

DACTYLOCALYX. — See Figs. 274, 275 and 276, Plate
XV, for skeleton fibre, and Figs. 240 and 241
for structure of the skeleton and gennnules.

Sub-Order 7.

FARREA. — See Fig. 277, Plate XV, for the structure
of the fibre and form of the skeleton ; and Fig.
311, Plate XXI, for dermal structure.

ORDER 3. — KERATOSA.

Sub- Order. 1

379. SPONGIA, Linn&us. — Showing the irregularity of the
disposition of the keratose fibre. X 50 linear.
See also Fig. 261, page 13, for the structure of
the fibre.

OP THE SPONGIAD^E. 289

FIG

380. SPONGIONKLLA PULCHELLA, Bowerbank. — Exhibiting
the nearly rectangular mode of disposition of the
primary and secondary keratose fibres of the
skeleton. X 50 linear.

Sub-Order 2.

378. HALISPONGIA, Blainville. Showing one of the large
primary keratose fibres, containing siliceous spi-
cula, and the irregular system of small aspiculous
keratose fibres. X 175 linear.

Sub-Order 3.
-. CRALINA, Grant. See Figs. 262, 2G3, Plate XIII.

Sub- Order 4.
— . VERONGIA, Bowerbank. — See Fig. 266, Plate XIII.

Sub- Order 5.

-. AULISKIA, Bowerbank. — See Fig. 267, Plate XIII,
and Fig. 268, Plate XIV.

Sub- Order 6.

381. STEMATUMENIA, Bowerbank. — A section at right
angles to the surface of a young Stematumenia
exhibiting the regular semi-areno fibrous skeleton
and the fibre-membranous interstitial structure in
situ. X 175 linear. See also Figs. 256, 257,
and 260, Plate XII, and Fig. 269, Plate XIV.
Page 211.

19

290 ANATOMY AND PHYSIOLOGY OF THE SPONGIADJE.

Stfb- Order 7.

PIG.

3S1. DYSIDEA FRAGILIS, Johnston.- — See Fig. 271 for a
portion of the skeleton, and Figs. 270 and 272,
Plate XIV, for fibres of the skeleton.

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