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Full text of "A Manual of Zoology for the Use of Students with a General Introduction on the Principles of Zoology"

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mmiiiii 

6000306640 




/9^3^ ^-^^t 



A MANUAL OF ZOOLOGY 



y THE SAME AUTHOR. 



TEXT-BOOK OF ZOOLOGY, 

rOR THE USE DP SCHOOLS. 
Crown 8vo, with numerous Engravings on Wood, 6s. 

" TUs capital introduction lo natuiBl history is illustrated, and well got up in 
every way. We should be glad lo see it gcoerally used in schcxils." — Miditai 
Prtit and CircHlar. 



II. 
INTRODUCTORY TEXT-BOOK OF ZOOLOGY, 

FOR THE USE OF JUNIOR CLASSES. 

With 137 EngisTings, 3s. 6d. 

" Very luitabte for junior classes in schools. There is no reason why any one 
should not become acquainted wiLh the principles of the science, and the litcts 
on which they are based, as set forth in this volume. "—Zaiih/. 



MANUAL OF ZOOLOGY 



FOR THE USE OF STUDENTS 



WITH A GENERAL INTRODUCTION ON THE 
PRINCIPLES OF ZOOLOGY 



BY 

HENRY ALLEYNE NICHOLSON 

M.D., D.Sc., M.A., PH.D. (Gott.), F.RaE., F.G.S. 

«oriSSO»OF ll*TU«»l. HHTOHV AHO ■OTANV IN UNIVBHSITV COUJBl«, TOBOKTO; 

FOBUKBLV LMCTURUI ON NATITBAL. KISTOtV IH THE UEDICAL SCHOOL DF KDINBUaCH; 

VlCI-PltESlDINT OP TKK CKOLOGICAL SOCIKTV OF KDIHBUIGH, ETC. 

AVTUOH OF ^ADVAKCDf TIXT'BOOK OF ZOOLOGY FOA TKK UIK OF SCHOOL! I* 

'TBXT-VOOIC OF CffOLOOV;' 

'■UAV ON THIl CIOLOCT or CUHBIUHJlNn AND W«ST1I0»«LAND l' 

'cRArrouTn or thb skiddaw sekies,' >tc. etc 



SECOND EDITION 

REVISED AND CONSIDERABLY ENLARGED 



WILLIAM BLACKWOOD AND SONS 

EDINBURGH AND LONDON 

MDCCCLXXI 



nf Xirtf ^ Tnuu/atHm it ttur^d 




PREFACE TO SECOND EDITION. 



The call for a new issue of this work within little more 
than six months after the appearance of the last, is a 
very gratifying proof that, in spite of its defects, the 
work supplies a recognised want, and that the Author 
has to some extent succeeded in the objects aimed at 

With regard to the present edition, the Author need 
only say that the entire work has been carefully revised, 
and all the more striking discoveries of recent date have 
been noticed, whilst some errors have been corrected. 
Coasiderable additions have also been made, especially 
in the department of Vertebrate Zoolog>-. The Author, 
however, would ask his readers to remember that the 
compass of the work will not admit of the introduction 
of many details, which must be sought for in other more 
extensive treatises, and that only the more important 
bets of Natural History should be looked for in a work 
of such limited size. 

I.astly, no change has been made in the plan of classi- 
fication adopted in the former editions of this work, and 
based essentially uiwn the views put forth by Professor 
Muxley. It is true that this classiAcation is a modern 



vi PREFACE. 

one, and that it departs widely from older arrangements. 
The Author, however, must seek his excuse for its adop- 
tion — if such be needed — in his firm belief that of all 
classifications this approximates most nearly to a nat- 
ural one, and that though subsequent researches may 
compel its partial modification, its broad outlines will 
long endure unaltered. 

TOKONTO, Octolnrx, 1871. 



PREFACE TO FIRST EDITION OF PART I. 

In bringing out the present worlc, the Author has been mainly 
guided by the recollection of his own difficulties as a student, 
and by the belief that he is supplying a distinct want. Many 
excellent and original works on Natural Histoiy are extant, 
but they mostly labour under disadvantages wliich more or less 
disqualify them as text-books for students. So vast, for in- 
stance, liave been the additions to our 2^ological knowledge 
witliin the last few years, that no work on Natural Histoiy, 
except the most recent ones, represents adequately the present 
state of the Science. Under this inevitable disqualification all 
the older Manuals labour. Other works, again, of the most 
profound research, are unsuitable for ordinary students from 
their bulk, cost, and, more than all, from their very profundity. 

The Author's aim, therefore, has simply been to present to 
the ordinary student those leading facts in Natural Histoiy, the 
knowledge of which is essential, but which lie scattered through 
the pages of other larger and more costly works, inaccessible 
to those who merely desire to learn the oudines of the Science. 
In carrying out this object, it is unnecessary for the Author to 
remark that he does not lay any claim to originality. He 
tna\s, however, that he has succeeded in laying before his 



I'KKFACE. 



VU 



a mere mass of undJ^cesteJ fact&, but something 
IDce on orderly and systematic review of the main points le- 
qiured to be knon-n hy tJie student. The Author is conscious 
u( ninjr iR)i>erieclions in his plan, and aUo in the execution of 
kis phn. The subject, however, is so extensive, aii<I so con- 
guaily changing, that he can reasonably claim some indulgence, 
if the biief leiMiTe-time of a bu.sy life has not enabled him in 
evtsy respect to keep abreast of the latest discoveries. Such 
ddects as there may be, arc, it is hoped, of such a nature as 
not to diminish the value of th« work for ordinary students. 

Acoongst ihc sources upon which the Author has mainly 
dnwn, it is, perhaps, invidious to mention one more than 
UMlher. He feels, however, bound to acknowledge with 
gtatiiude the very great assistance which he has deiived from 
the various works of Professor HuxJcy. 



EniNauacH, MKtwiitr 3, 1S69. 



hm 



PREFACE TO FIRST COMPLETE EDITION. 

Ik (BOtng the first part of the present work ia a lecond edition, 
ud in bringing out the second part, the Author has little to 
sdd to wlui he his already said. 

The chief point upon which it may be desirable to say a few 
wordu is, as to the object aimed at in the ItUrodui^tory portion 
of the work. The Introduction is intended to exhibit lo the 
itodcnt, in as brief a form as possible, the leading principles 
of Zoohigical Science. Tlvese principle* arc of the hii^hesi 
importance, and no adequate knowledge of ^^ootogy can be 
attiined without their full comprehension. At the fAme time, 
the piiociplcs in quesdon depend, in nuny ca.se!;, upon data 
rliich arc only evolved during the systematic study of the sub- 
FoT this reason, it is not to be expected that the (tudeoX 



Vlli 



PREFACE. 



should find himself faily able to comprehend the Introductory 
portion of the work, whilst still standing at the threshold of 
the subject Whilst the student therefore, will do well to 
glance over the Introduction before commencing the study 
of the systematic portion of the work, he must be prepared to 
find many points which he can only liilty grasp after he has 
attained a knowledge of the leading modifications of structure 
exhibited in the Animal Kingdom. The Author has only to 
add that the first part of the work (on the Invertebrate Ani- 
mals) has been carefully revised, and, as far as possible, 
brought up to the present level of the Science ; whilst the 
illustrations, with very few exceptions, have been drawn upon 
the wood by himself. 



EdINBUKGII, Dectmber I, 1S70. 



CONTENTS. 



PAST l-TtrrBB.TBBBJLTB AUIMALB. 
GENERAL INTRODUCTION. 



Difiiiitkm of Biology and Zoology— Diflercnco b«ween ori[»ni«««l 
and UMOifaouM bodjo — N»lore of life— Vital <brc« — Difler- 
awM between uiunAli and pluitt — Marpholajnr end pbqrriolosjr 
— DUTercnce) betwecai iljffercni kniimli — SjicciallMtlen of liinc- 
lio«— Moqiliologicit CjjM — Von Bacr"* kw of diveloMnenI— 
HonuJopr, uuIoct, ood hoini>mar|>bi*m — Comblioii of growrlh 
— ClMrinciition— Pefinitioin of ipociei — ImeotxiUlity of a linear 
ilMiiliialiiiii ITqiiiiilniliiiii "i mil teprodnctioa — Noci'icituJ 
niiRidnetlaB— GcniBuitlon and K»ion— ReprudnctSon by inlcragJ 
gMRnWlon— Alternation of (encration*— Puthcnocmoli— De- 
vdopwcM, tniufonmtion, and TDetamorphosiji — iipontuiooiit 
SetwnlioQ— OriBin of tpecici — Diitribulion, ccoBnphiotl and 
gMlogtcal, IH3 

CHAPTER I. 

C«a«*l dwmMen of the PtoioMB— CbMlAcMion of the Pntatoa— 
CnpriiUdN — hon«pemij(v 44-48 

CHAPTER II, 
Gnati dunctcn o^lhe Rluxopoda—Moncni— Amabei, . A^S* 

CHAPTER III. 

Fennuntfen — Clanilicalion uf the Foraminirria — Gathybios — Como- 
Uilii, CocmiphcTn — Affinitici of the Fonm in I fen— Distribution 
of Fonunintkia in ipicc— Diitribulion of FocunioifciB in tine, JJ-te 

CHAPTER IV. 
RaiBotajia— AcanthooittTa! — Poljcjnlina— ThalaauMllida, 61.^3 

CHAPTER V. 

SptHp*— Nmhn ef Sponfet— CUwIicalion of Sponeldii— Diitrilni. 

tiCB of Sponge* in ipaoe and in timr — AfEnifiti ofSfOTi^a, (>V10 



CONTENTS. 



CHAPTER VI. 

Infiuoiim— Oidn Cilimts— Ssctoria—FUgelUU— Noctilaa— Phoc 
phoRMcnce of the Ses, To-77 

CHAPTER VII. 

Geneiml chumcten of the Ccelententa — Diriuoiu of the Ct^ententi 
— HydroM* — Genenl tenninologj of the Hjdroioa, . . 78-81 

CHAPTER VIII. 

Dividou at the Hydroioa — Sub^clus Hjdioidi — Order HTdiidm — 
Order Coiynida— Reproduction of Hydtrnda — SeituUrid& — Cun- 
puuluida, 83-93 

CHAPTER IX. 

Siphonophoim 01 Oceanic Hydroioa — Calycophoridx — Dmsions of 
CalycophoridK — Physophoridse— DiviMons of Pliysophorid«, 93-ico 

CHAPTER X. 

Diicopfaon— Stmctiue of Medotidx— Value of Medndde u an order 
oTHydnno*, 100-103 

CHAPTER XI. 

Lucenuuida — St^^tnophlhalmate Mediute — Lncenuuiadx — PetagidsE 
— Khiioitomidae — Reproduction in Rhiioitomidx — Sub-clau 
GraptolittdaE — Definition of the Sub-data — Structure of Gnpto- 
litei, i(H-iIi 

CHAPTER XII. 

Dlltribntion of Hydroioa in space — Distribution of Hydroioa in time 
— Oldhamia— Cotynida — Sertolarida — Graptolites, . . 113.114 

CHAPTER XIII. 

General chaiacten of the Actinoioa — ZoantHaria Malacodennata — 
Actinida: — llyanthidie — Zoonthidx — Zoantharia Sclerobasica — 
SderolBiic and Sclerodermic Cotals^Antipathida— Hyalone- 
madx — Zoanthana SdeiodermatA — Gemmation and Rtaion 
taianKn Corals, I14-135 

CHAPTER XIV. 

Alcyoaaria — AlcyonidK — TubiporidK — Pennatulidx — Goi^onids — 
Red Coral ja$-iat 

CHAPTER XV. 

RvEoaa — Distinctioos between the CoixUa of the different Orden of 
Actiiioia«, 128-130 



CONTENTS. 



Xl 



CHAPTER XVI. 

Cteaopbont — Gawnl chanclen— Anilomy of Plenrobnchi* — Dni- 

aonsof Cunophor*, ■3^134 

CHAPTER XVII. 

DiUribnlkm of Actiaonxt in tmce — Coral Rnft, tlieir sInictDie, uiil 
mode oforij;!!! — Diitiibution of Actinoioa in time — Tabular view 
of the diviiion* of tbe Zoanthariit Sclerodennau and Rugou, 134-140 

CHAPTER XVHI. 

Aimoloidi — Ceneni charartera of ihe Annul oidn— General ehanclen 
of the Ethinofiemula — rtevelopment of the EchinodcnnalB — 
Uviikuu of Echinodernuua, ■4t-i44 

CHAPTER XIX. 

Edunoi^M— 0«Mnl characuo— Aaalomr of Cchinu»— DivWoas of 
EduMidM M«->SO 

CHAPTER XX. 

AjUfoidcB and Ophiufoldeit—ticncral characlcrt of the Aateroidea— 
KrUtooi of tha Aitonidt* — Grreral churaclcn of ihe Ojihiuroi- 
de»— FaaiBs of the Ophioroidea <50->5S 

CHAPTER XXI. 

CriDoido, Crtloklea, and Blatloidea — Central characiorf of Ciinol- 

de«— (XCptoidea— Of Blaitoldca, 153-ite 

CHAPTER XXII. 
Holotboimdek — GstcraJ ehanelcrv— Families of HoloCburoidea, Ite>l6a 

CHAPTER XXni. 

Dbtribntion uf Echinodermata in ipact^— nntribnCion of Echinoder- 
tuta kn time — Crinoidea — BbuioitJea — Cfiloideo — Atteroldea — 
Oi^iiinroidca— Echinoideo — llolothuroidca, . . . I63-I0J 

CHAPTER XXIV. 

Scsleddji— Gmnal cluracun uf the cIbu ScolKJila— EnlOM* — 
nilyrtmii — Tsaiada — Siructiue and development of the Tape- 
awM~ll]nlaiidi, 65-171 

CHAPTER XXV. 

TtaMtodaud Tuibdlaria— General eharaclen of the TrcmalocU — 
GoMfll duncten of the TurbcIIum— rUaarida — Nemer- 
IM*. '7>-I« 



xii CONTENTS. 



CHAPTER XXVI. 

Nenutelmu — Acuthocepluda — Gotdiacea — Neowtoda — Puantic 

Neinatoid»— Free Nematoids, ■7S->79 

CHAPTER XXVI I. 
Rotilen — Genenl chancten of the Rotifen — AiEnitie* of the Roti- 

few, "79-'84 

CHAPTER XXVIH. 

Annnlota— General chancten of the Aimalaia— Genenl chancten 
of the Anajthropoda — Claai Geph;rea — GetienI chaiacten of the 
cla» Amiclida, 185-189 

CHAPTER XXIX. 

DiTidont of the Annelida— Hinidinea—Oligochteta — TuUcola — 
Emntia — Distribution of the AnneUda in time — Tabular view 
of the Annelida— Class ChKtognatha, .... 189-199 

CHAPTER XXX. 
Aithropoda — Genenl chamctcis — Divmoni of Aithropoda, . 199-aoo 

CHAPTER XXXI. 

Crustacea— Chancten of the class Crustacea — Genenl moiphologr of 
Crustacea — Divisions of Crustacea, 200-108 

CHAPTER XXXII. 

E[»ia« — Ichthyophthiia — Rhiiocephak — Cirrioedia — Chancters of 
Ciiripedia — Derelopment — Reprodnction — Divition), . . 208.215 

CHAPTER XXXIII. 

Entomostnca — Lophjrropoda — Ostracoda — - Copepoda — BnncMo- 
poda — Cladocera — Phyllopod* — Trilobita — Merotlonuoa — 
jCi[dioinn — Euiypterida, 215-323 

CHAPTER XXXIV. 

Malacostraca — Edriophthalmata — Lfemodipoda — Amphipoda — Iso- 
poda — Podm>hthalmata — Stomapoda — Decapoda — Macrun— 
Anomun — Biachfura, 333-231 

CHAPTER XXXV. 

"^Mribotioa of the Cnutacca in space — Distribution of the Cmitacea 
tattan 333-334 

CHAPTER XXXVL 
*in ud divniau* of the AiBchnida, . 335-138 



CONTENTS. 



XIII 



CHAPTER XXXVII. 

nioaa of the Anchalda — Podowoula— Acariiu— A<3darthrotO' 
autft— Fed^fil— AniKula, i]8-244 

CHAPTER XXXVm. 

'Urriapoda—Gcnenl . clunclm of ihe cU»~ChiIopoda— ChiIo£. 

Mllu— Paoropoii— DbWbulian of M/riaiwda in umc, . 245-248 

CHAPTER XXXIX. 

eral chanetcit d tbe tnwcu— Mcum«rpbo»e« of InMctt— Smm 
of Imocu, mO-'ST 

CHAPTER XU 

^ivinant of Ui* Incet*— Anoplura — Mnllophs^ — Tliywnm— 
Hernlplcra — Oithoptna — Kenntpwra — A phanipttra — Diplcia — 
Ltpldoptcia— H]niieiiopl«t3— St^piiptcra— C'olcoplno, , 157-173 

CHAPTER XLI. 

|C«iwnl chancten of the fttoUiura— Digtilive system— CirculatOT 
mkiB— K«»latocT mtem— Nervou* mlcca — Kiproducliun — 
Shell, 174-37S 

CHAPTER XLH. 

IoHomaUI*— Polytoft— DiiiinciioiM between the FoTj-io* and Hy* 
drOMO — Polypldc of th« Poljioo — Aiulomy of ihc Potyio* — 
Keprodnction and devttoptncni— OivUciai of [he Poljrico, . 379-137 

CHAPTER XLUI. 
Tnnicata— GcnenJ chancier*— Dnelopment— Type* of^Homotogis 
— Dlviucnt, a3;-a9i 

CHAPTER XLIV. 
finchiopoila — G«ncr*l <h»raeteti — Shell— Artii»—Atti«l iyttem— 
UvUiou, 192-197 

CHAPTER XLV. 
Disliilnitioa of HaUuicoida in ^Mce^Dlatrlbulion of Malluicolda in 
Iww, 197-199 

CHAPTER XLVI. 

G«neiaJ chancten and Jividoni of the MoUusc* Proper— Lam elli- 

IbnncbUta — Ccoeral characters ami aniiomjr — DlvbiDot— yami- 
Uaof the UmelUbruchiata 300-J08 
CHAPTER XLVII. 
MphaU— Cutcropoda— Geoenl chaisctcn — DeiclopmcDt— Shell 
r ' 



XIV CONTENTS. 



CHAPTER XLVIir. 

Divitions or the GKsleropod«— Prosobranchiau — OpiathobrandiialB— 
Heteiapoil& — Polmoiute Gasteropoda — Families of the Gastero- 
pwl«, 3'3-3l9 

CHAPTER XUX. 
Pleropodft — General ehacactera — Diviiions— Families, . 320-311 

CHAPTER L. 

Cephalopoda — General characters — Anns — Respiratory organs — Re- 

prodnctive process — Shell— Diviuons, 3>i-3i7 

CHAPTER LI. 

Dibranchiate Cephalopodi— Genera] charactera'-^ctopoda — Ar^on- 
autidse — Uctopodidir — Decapoda — TeuChidie — Sepiadx — Spini- 
liifce— BelemnitidK— Tetrabranchiate Cephalopods— Simcture of 
the Feailjr Nautilus— Shell of the Telrabranciiiata— NaulilidK— 
Anunonitidae— Families of the Cephalopoda, . . 317-335 

CHAPTER LII. 
Distribution of the MoUusca Proper in time, .... 336-338 

Tabular view of the chief lubdivisions of (he Invertebrata, . . '339-343 



FABT n.-TXRTZBBATB AXnJKAIjB. 

CHAPTER LIII. 

General characters of the Vertebrata — Oaaeous system — Digestive sys- 
tem — Blood — Circulation — Respiration — Nervous system — 
Organs of tCQM — Reproduction— Divisions, . . 345-361 

CHAPTER LIV. 

General characters of Fishes— Integumentaiysystem — Osseous system 
— Fins — Respiration — Circulation — Digestive system— Swim- 
Uadder — Nervous system — Ol&cioiyoigaos— Reproduction, 363.375 

CHAPTER LV. 
Phaiyngobranchii— Martipobranchii, 376-3S1 

CHAPTER LVI. 

Teleostei — Snb-OTders — Malaco^eii— Anacanthini — Acanthopteri— 
I'lcctognatM — Lojdiobranchu, 381-3SS 



CONTENTS. 



XV 



CHAPTER LVII. 

GaMHdd— Sabmcdcn— LqridoeaniHdd— nMoguKHdci, . 388-394 

CHAPTER LVIll. 

*nd Dipnoi — Sub-«den of Elumobtanchi! — llolo- 
ccpholl— Plaginioini— Upa«i, J94-40S 

CHAPTER LIX. 
DtotdbMlcM of FUfcct ia tUniv 403-405 

CHAPTER LX. 
Geaenl chmctenoTllie AmplubU, 406-40! 

CHAPTER LXI. 

0(4en of A»phibi> — Ophiomoi|ihi— Urodcia — Anour* — Devcli^ 
mailoTPrac — PuniEicmaf Anoan — Labjrinthodontia — DUtribu- 
tion of AatpLibik in lime, > 4oS-4it 

CHAPTER LXn. 

Gcnnsl tbuactcn of Kqxilia — Endosktlecon — Exoikclelon— Dieo* 

live ^tttn— CuculaioiytjAem— Rapimoiy tyttGiD, . . 419-413 

CHAPTER LXIII. 

Uiviuom of Rcplilia — ChdoDU— General ch>ra<(cn of Chelonum 
Rcptiki — Diitribulion of Chelonla in lime — Ophiilia— General 
dMnclen ol Snakes ~ Sub-ordti* — Diuributbn u( Ophiitia In 
«!««. ■«>3-43S 

CHAPTER LXIV. 
Ijiwtila FiMilJM et LACcnili*— DUtiibullon or I^ccnllli b limc 
— CmeodiUa— Sub-ordcn of CiocodlUi— Ditinlnitlon of Ctom- 
dUn in Urn*. 4J5-445 

CHAPTER LXV. 

btloct oadcn of Repillm— IchthyoptciT^ — S«uropt«tT^— Ani>- 
mododtia — Pwouuik — Dtnouuria, 445 '4S' 

CHAPTER LXVI. 

GmnI chwactec* of the cIm* Av{>— Fothcrt— V«itcbnl column — 
SbtU — Fectonl arch o&d fotciimb — PcWic accb and hind-limb 
— Dtpslivc i>-ilnn — Respinturjr ijsictn — Circulaton lytttm — 
RqtrodactiTe orsu»— Nerrooi tjilcmiod oipUMofSeOK, . 4SJ-47a 

CHAPTER LXVIl. 

(kMol dlvWoM of Ac clui Am— Chancien Bnd famUlM of ihc 
otdM fUtatoroa— Cfaancim and Jiunjlio of Oralintorct, . 471-^ 



XW CONTENTS. 



CHAPTER LXVIII. 

□uiaders of Conores — Chaiacten and Mctioas of Ruotes — Gtlli- 
nacd — Columbacei, 484-491 

CHAPTER LXIX. 

Qkuaders and Eunilies of Scauiores — Cbancters of Idmuotcs — Coni- 
Toities — Dentiiostres — TcDuirostrcs — Fissirostres, . 492-501 

CHAPTER LXX. 
Chaiacters and Sectioiu of Riptores — Characters of Sanmne, • 5<>i-505 

CHAPTER LXXI. 
Diitribution of Ave* in time, S05-5<>S 

CHAPTER LXXI I. 

General cliancten of the MBmmalia — Skeleloa — Pectoral arch and 
fore-liinb— Pe!»ic arch and hind-limb — Teeth — Dental fonnnla — 
Digestive system — Circulatoiy system — Respitatoiy system — Re- 
productive system — Mommaiy glands — Nervons system — Integu- 
mentaiy appendages, 509-511 

CHAPTER LXXHI. 

Cbusifieation of the Mammalia — Sjnopiis of the Mammmalian 

orders, 523-526 

CHAPTER LXXIV. 
Characters of Monotiemata — Characters and divitions of Martu- 

piaU", S»7-S3fi 

CHAPTER LXXV. 
Chancten and families of Edentata, S37-543 

CHAPTER LXXVr. 
Cbacacten of Sirenia — Chanu:t«Ts and families of Cetacea, . . 542-551 

CHAPTER LXXVII. 

General characten of Ungokta — Perissodactyla— Aitiodactyla— Ru> 
minantia — StmctDre m the ilomach in Ruminants — Dcntitioa of 
Ruminants — Sections of Ruminants, 551-568 

CHAPTER LXXVII I. 
Chancten of Hytactndea — Chaiacteis of Probosddea, . 568-571 

CHAPTER LXXIX. 
Chamcten ol Caxmyom — Knnigrada— Plantigrada— Difiligrada, 573-586 



CONTENTS. 



XVll 



CHAPTER LXXX. 
CluuactenofRodentift— FMuiliesof Rodenti*, . . .586-593 

CHAPTER LXXXI. 
Qwmctcn of Cheiniptenu— Sectioaj of Cheiroptera, . . 591-595 

CHAPTER LXXXI 1. 

Chtncten of Insectivoni — Families of Insectivon — Gileopithe- 

a«l»e, S9S-S98 

CHAPTER LXXXIII. 

Chanctenof Qoadnunuu-^Sectioniof Qiuulniman«--StTepsiibui& — 

PlatjThiiu— C&tuhiiu, 598-606 

CHAPTER LXXIV. 
Chaimcten of Bimana, 606-607 

CHAPTER LXXXV. 

EhMnbutJon of Mammalia in time — Geographical succeuioQ of or- 
ganic formi — TabuUr view of the chief sub-divisions of the Ver- , 
tebrata, 607-630 

Glossakv, 611-651 

Index, 653-673 



xviii 



LIST OF ILLUSTRATIONS. 



I. Grtgarima of the £>rth- 

wonn, . . , . 

a. tiSorfhiAi^Y of SAiMafoda, 

3. ActiUBphryt »/, 

4. MoTpholoey of Foramini- 

fkfa. , . . . 

5. ffKmmali/a IXBigalui, . 

6. Aiantlumttriiia and Pefy- 

7. MoijAiaiogy of Sadularia, 
a. Diigmn ot SfoHgilla, 

^g. Marphok^asdreprmluc- 
tion of Sfonfida, . 

10. Morpholoey of Infusoria, 

11. yatiMUBla, S/ai/«r, and 

Vortialla. . 
13. Morphology of ^^nuM, 

13. Morpholep of Ctrynida, 

14. ReproductiTe proceuei of 

Hydttaoa^ 

15. Medusiform gonaphoic of 

16. Titinlaria indit/int, 

17. Seriittaria finnata and 

Camfanularia lugUcIa, 

18. Morphology of Cdeaalc 

Hydroioa, 

19. Difhyti apptndiculata, 

90. Phytalia vtricutus tmd 

Vtlilla VMlgarii, . 

91. Morphology of 3/af«nifa, 
33. Group of nalccd'cyed i/e^- 

•u<<. .... 
33. tMcemaria auriiu/a, 
a4. Development o( LutrT' 

narida, 
aj. Generalive loSid of Chry- 

laara 

b6. Generative nOid of /fit- 

xosloma, 
37. Morphology of Grapto- 

liles 

sB. Didpmtgraptm V-fnuItu, 
»j. Tranjverse seclion of an 

ActtHoiodm and Hydr^ 

tttn 



FAG* 


fm;. 




30- 


47 


31- 


49 




5" 


3a. 




33- 


54 




60 


34- 




35- 


6t 


36 


63 


37. 


6S 


3B- 




39- 


£6 


40- 


71 


4'. 


75 


4!L 


84 


43- 


86 






44- 


87 


4S- 


8S 


46. 


89 


47. 




4«. 


91 


49- 




JO- 


94 




96 


S'- 




5»- 



99 

lOI 

109 
los 

107 

loB 

109 

til 
i'3 



"S 



Diagram of Actinia, 
Actinia Testa and .liracj 

HOCtis aiHda, 
Morphology of Corals, 
Sclerodermic and Sclero- 

bosic Corals, 
PiKKolula fkesplurta, 
Virgnlarig miraiilis, 
PUurv^rachia fiiicMS, 
Morphology of Ctcnopkora, 
Slructurc of Cotal-reels. . 
Morphology of Eckinotdta, 
Cidaris papillffta, 
Laiva of Bckima. 

grarn of Eckintis, 
Cribcila oculala, 
Ofkiura texturata 

OfkiKoma mglala, 
Rktaoainus LjOjotcnsis, 
Comatula rvsaaa, larva 

andadtilt, 



Dia- 



and 



Echiiwifkitritcs aurantium, 159 



53- 

54- 

55' 
56. 

IS: 



THyotu pafillcsa. 
Morphology of Titniada, 
Trtmaioda. 
Morphology of Tiirtit- 

laria, . 
Edt inorkynckus gigas, 
AngnillMla aciti and Oery 

faimns stagnalii. . 
Hydatina stnta and MiU 

ctrta ringens. 
Diagram M an Aonuloie 

animal, 
Syrinx nndns, . 
Diagrammatic section t>f 

an Annelide, 
Medicinal Leech, 
Sttfnla eanturtnpiieata 

and SpirorHt cfmrnunis, 
Nmis, 
Ejranl Annelidei, 



61. Diagram of the Somite 

a Cnutacean, 
6a. Morphiriogy of Lobster, 



r'S 



117 
rao 



"7 
1*7 
"31 
13a 

'36 
MS 
.46 

14S 
15' 

IS4 

156 

157 



of 



161 
'69 
17a 

'74 
'76 

177 

iSi 

185 
186 

187 
190 

'93 
196 

197 



303 
*>5 



LIST OF ILLUSTRATIONS. 



XIX 



8J. 

Ik 

S. 
«»■ 

T* 
J'- 
7* 
73- 
7< 
75- 

r> 

J5; 



79- 
So. 
It. 

•a. 

n. 

9«- 
9*. 
«- 
«- 



let. 



103. 
•t* 

IS 

M*. 
■09. 
Ita 



III. 
III. 
"3- 



Luv« uul (dull of AiJUMt- 

rti ftriarmm, 
LocomoDn touhk of ''- 

/jaiu. . . . . 
Uoittbology of CirTif4Jia. 
FfoWaier Bntrmatmea. 
CUnufiabti diafMoMmi, . 
MaphalogT of TrilobMctt 
Umulmi fvhfttmm. 
Pltrygitai Amf^um, 
Ctfrtlla f*aim». 

Wood-OM. 

/AWMnU Ml/MPfl, . 

»pMtr<r>b UU^uk 
Lwa (Zmu) of Ctih 
Uotpbolagr e< ArathnUa. 
Pytirtf^nmm liltoralt, TV 
trvateAm UUmtl, and 
tffjr^ain gUtulHI. . 
Seoipion, 

Cratipcde. 
UiUliNde. . . 

Dl^MBI of loKCt. . 

oT dw llouih 



Oniiu oT 



Id 



•09 

a» 

»4 

MO 
■13 

an 

•Jl 

»3» 

W 



MO 

M" 

US 

**7 
949 

»S< 

as* 

»ss 

059 
•61 

•«9 

:^ 

:s 

»«9 
»7i 



DUHdnmHm of B«c(lo, 
MiMniiliiiih or ihe 

M«a»» UMb. . 
BMnApU). . 
CockTOKh iDUuaK . 
liUnMOty LoniW. . 

AptaliM. . 
TvaMo. . . 

TIfmla rItrttM, 
J^tntu trauiea. 
Ctttmi UrwiptrJa. . 
TViMinMp frtaa lirt^, 
tijintua r»/4. 

A/tUtfiHAt vulgjni. 
CtMita martin >nd Ctrr- 

mlit nltMrni, , aja 

DMcnun o( • MoIIuk. . m 

Mofptroloc)' of fWyie^. . aM 
fiaitrv ITKatiiU. l'.tt- 

trrta, wmI Ijtflttfiu ay- 

iMJUMmi. . aSj 

Uorpbolot^ at TumiMlt. a» 

IJagHtt amatiaa. . agj 

Ttrttrmiula vitrt*. . , 094 

Analoniif a{ Mm armaria. Ms 
SMb of tjmtUiiraiJk- 

i'fa 3H 

Odonio<>boKorilic\VheIk. 309 

A^HlJariit wt^lmlila. 310 
ICobMuoiklouj and S|. 

phonotiomaiAia SIhVm. 314 

Oirii yiAailtai, . 315 

Cariitaria ijmtiam, , iij 

Uma* Sitr€r*f4. . . 316 




114. ClaaJmra fyramtJata aad 

f-Kvifria t^itatafUa, 

115. SrfwJi AiUxlifa, . 

116. Oifti^"! cj'TirJ, 

117. Paper NwllilUh 
tiH. Diagram of BtUnmUIe, 
119. I'cvljr NauUlui. 
lao. Dla^m of (he Sipbuncte 

and Stpta lo the ihcIU of 

•■riuut Tcmbranchliue 

Ophalapodi. 
ISl. OrttMtnu trftavttr. 
l». Sbtlb of Svxindvy C«ph- 

■lopodi, 
U}. Tniuienc loctloni of (ho 

botjtf of an invtrubni« 

•Dd a nncbnic •nlmol, 
n^ EmtuyologT of Vcnebnd. 
lay LumtarVfn^braDrWbalt. 

•nd <tlik{:nLin of Ihonulc 

*rnrlira. . 
i>6. Slnlpton of lli« Ettairr, 
1*7. Pccloral I.imt) of Cblinpon- 

m .... 
(99. PdvLc Limb of C'bkmpMi 

<e*, .... 
(19. Dlif[nni of ihe digncive 

iiyileni c( a Munmal. . 

130. Blood-coriiUKl« of ytrli' 

trala. .... 

131. DiasninofilMCiTciilition 

of « MammaJ. 

ijj. Skeleton of the Conunoa 

Perch. . . 

ij*. Skull of the Cod. , 
tjj. Oi broidci and bmncbiol 

uctxa of lh« Penh, 
Ijtv pKtonI Ijmbt of l-'iihm. 
I]7. Oinlliwof /'fri'iirrdiiillt'4, 
130, HonMBWoJiMdlwiaroMr- 

MlTaib. . . . 
139. Dianwn of <he CiKulaUon 

oi ■ Fiih, 
140^ DioKTUD 01 the LadccM. 
I4t, iMiiptvy. 
14). Hcan of Tclnnlras and 

OmeaA Fiihtt, 
t4}. Gymn.'Jai iltitniits, 

144. Kk^attui fnHttjIui, . 
14$. OffnifMH tsntatMi. . 
1481. PpMl^rwiaxAOilriit^, 
147- Cifialatfil lytilii. . 

145. Cmcaitimi aod PttrUhAjt, 

149. Head of PUtied Dog-fiih, 

150. OnAoriu and CUi««rv, 
>ji- R»im margiiala, 
tji. Ijfi4aiirta 0amt€itai. 
■53, liplnciandTeclhof I'aloto- 

■oic Elaimetrairtkii, 
154. ////•■ /mvtemd. 
I5J. SififiufI aaauUlat, 



3» 

3>8 
3»9 
331 



333 
334 

33> 



34« 

3« 



3S<t 
JJ' 

3S3 

3S4 
3U 

3SS 



3f* 
365 

3«7 

368 

37» 

37* 
377 
379 



3«7 
391 
SM 
393 

39* 
400 



*9 



HL ULJHH 


^M XX LIST OF ILLUSTRATIONS. ^^H 


^^B 15$. Ptvttml attguiMti, . . 41a 


198. fool of Tavmy Owl, utd 1 




HondofUluiieOwl, . S«> 


^^M tgL Trilm iriilGtai, ■ 4>3 


199. Heodof Vuliuiv, . 543 


^B iw. SIulMon ot the »>!« . , 414 


100. jtrriirt^eryri macnin, . $04 ^ 

aoi. Focc-lmiba of Hoik Mid ■ 

Dot. . . . - SW ■ 


^^H it). FeMprlntsofB^.dir'iMi^ 




to*. Trvlli of Cbimpuueck . 5>S 


^H 16a. Skull oT a S«pent, . . «» 


104. tVlvb of Kin(iLioo. • J30 ^ 


^^H 163. Diagranxiit (he drcuUll«ii 


^^H in Rfpliln. . , 491 


Boj. Koila or Kuigaroa-bwi. 330 B 


^H 164. Sb^lcion of Tortobe. . 435 


ao6. DcntJUon of Thjiatimitf ■ 


^^B i6j. ilinkVbitl Tunle. . . 497 
^^m IW. T-yt of Serpent >iiil H«>d 


and Hjftiprymma. . 5J3 H 
407. Myrmttiliiis/,tuiMiii. $36 H 


^^H of Vincr, . 4)0 


906. Hand o( lhr«e.loed Sloth, $38 H 


^^H 167. iV'uN /'■U''. ■ 43a 
^H lit. Mead of Ringed Snftke. 


ao9. dArHjy4«nu tmiualiu. , 540 H 


aio. Dugoiig 341 H 

an. SiuHtofnehlWliale. . J43 ■ 
•ta. Diwrom et Etaloco-plaus H 
Ofa Whale. . 547 V 
113. Fhji^tltr MMrvtffialMi, . J49 


^H or V^per, kod of Bliad- 


^^H t$g. IcuuiA. .... 436 
^^H 170, lllind-womi, • 4j8 


^^H 171. Cummem Skink. . 439 


114. Dtlfhiiimi iiH^ii. . 350 
aij. Feet of fiif K/j/ii. . jja 
ai& HndofTwo-harntdRhin- 


^^H 179. Held of ChiuDeltDa, . 44i> 


^H tji. Crttadiimvidgarit. . 443 


^H r74. SkuU at CneaJitui Uftt^ 


OCOM. . . . . SS* 


^^H 17^ liklA^tHarmi frmmmiii, 440 


ai7, SiomachofaShesp, . jm 
Its. Skull of homlcw Shoep, • sio 


^^H ■;£. FtatManrmi Mk^*i/etrmt, 44) 


1191. Head of the Hed-dter, . Jfij ^ 
mol K«wI of tho Koodoo. . 366 fl 
jai. Skull of the Indlaii £1«- V 


^^H 177. Htnixclftmi irftrimtrii, 449 


^^H 17S. Qnill-fcaiheT. . . 45J 
^^B 179. SluillcifSpui-vtandOocnc. 4SB 
^^1 tM. IVciionlamiuidnm-Uiab 


phant STO 

no. Skull of DtlmtOttTiim, . 57a 


^H ofPeneuin. . . ■459 
^^H iSi. ForT'limb d( jarhlooa, . 461 
^^H iSa. Hlnd-IImb oTLMd, . . 463 


M3. Fwt of Camitmi, . . S74 


a*]. SkuUoftheWalnia. . ^ 
»& SkutI of Jackal. . . 38) 
■(7. Skull of Lion, . . .514 


^^H 1I3. DSsMilne SHicm of the 
^^B Common Fowl, . 46s 


^^H 1B4. LungolGoow. . 467 


aj«. Skull of BeavCT, , , 587 


^^1 tlji Foot o( ConnonM »*A 


Mj. Common HamMvr, ■ . 59O 


^^H Bettk of Gocae. . m 
^^H 186. I«ckaM Psiinln, . 47« 
^H tt;. iJii o( CuHcv. HMd of 


e3& SImIxoo of Foa-bai. . 593 


aji. Head of Vampirc-lMI and ^ 

Fiu-bai. - - ' 5^ ■ 

>3X Skull of Hedgehos. . - 39o ■ 


^^H Sni|ie. uid Heikof Avocel, 4B0 


^H >M. CroMd Htran. . 4BJ 


133, Europaan htols, J9& H 


^H t*}. FaatofOiitlch.uulBtcait- 


134. Onrn Uookey. ' 599 H 


^^H bone of Emm, . 485 


133. gkullt of Onng and Eofo- V 


^^H 19a Aftttyt Auilniit. . 4S7 


pros adult. . . 60s 


^H 191. FoolofFowl.uKllIatdaf 


336. Jaw of Z>>v(mM^i'ii«. • te9 


^H Guinea.bwL . aSB 


^H 19a. Rock-p»t«B, ... 490 
^H 193. Foot of Woodpedcd, uid 


rrMtiaMbor. Anifiit*'- H 
rr'Hn. and /^tfilaaJiar, 6to ■ 

939. SlBtieioa m M^HUfium, 6i9 ■ 
a4a. OfyftaJtH titvljfti. . . 6ig ^ 


^H H«ad of Lovf^ird. . 493 


^H •94. Pwplc-«*pp«d Uirj-, . 494 
^^H 195. reel iind Hcwb of /mmj- 


^B wm. , . . , 496 


sut, SkeieWn al A/tgMtm ffi- 


^H 196. Had or BulUlnch. . . 49* 


ttrmUiu, . 6n 


^^M 197. Fool of PfncrtM Falcee, 


ata. Skalaionof .Vdf/.H'.ia. . 613 


^^^ «Ad Head of Bun»d. . 501 


I 045. Skdeteo of M.-kmmolli. 616 



PART I. 



INVERTEBRATE ANIMALS 



V 



MANUAL OF ZOOLOGY. 



CKKERAL INTRODUCTION. 
I. UkriNiTioN or Biology and ZooLocr. 

rNA-niRAL HiSTOkv, strictly speaking. Md lu the term itsctr 
[implies, tJvould be employed to dc^ignitte the stu<ly of all 
I'BOtunJ objects indiscrimiiulcly, whether these are organic 
or inoiganic, endowed with life, or exhibiting none of those 
bccswit vicissittida which collectively constitute viuUty. 
So enormous, however, have l>ecn the conquests of sciciw-c 
vilhin (he bsl century, that Natural History, iiung the term 
iD its olil sense, has of necessity been divided into several 
more or less nearly related branches. 

In the (tnx place, the study of natural objects admits of 
an obvious separation into two pninar>' sections, of which the 
first dc-ils with the phenomena piesenled by the inorganic 
world, whilst the second is occupied with the invcsiigntion of 
the nature and relations of all bodies which exhibit life. The 
former department concerns the geologist and mineralogist, 
and secondarily the naniralist proper as well ; the latter dc- 
pajtment, treating as it docs of livine beings, ix property 
designated by the term BkJogy (from o<»:, life, an^t Xc^*;, a 
iitcturtt). Biology, in lurD, may be split up into the sciences 
cf Botany and Zooloi^y. the former dealing widi plants, the 
bncr with aniiruls; an<l it is really Z^iifgy alone which is 
nowadsys understood by the term Naiuml History. 

In detetrnintng. therefore, tlie limits and scope of Biology, 
we are brought at the very thre(hol<i of our inquir>' to the 
«lue«ion. What are the differences between dead and living 
bodies ? or rather, in the first place, what arc the charactens^ 
tics of an organised as compared with an unorganised body r 

" TYm dtfcrcncn bdimn dew) <w inoipiniE bodinoo "*',?^L^^ 
•nd IMof or o<|:minc bodin on ihe olbcr, may b« i>k«i for *^J^^^^ 
pu r fm a u the tame as thoae bclwren mitrg'mitd and "S*""*" ^*3*^' 
11 b tfuke ine ihM oetuua living ben^ (fyrammi/rra) cannot be W.M to 

A 



MANUAL OF ZOOLOGY. 



1 



1. PiFFCRENCEE BETWEEN DeaD ANO LIVING BoDIER. 

In dclcmiinin([ this somewh.it difficiilt point, it will be best 
to ciuroinc the differences between organised and unorganised 
bodies smalim, and to compare them together systematically 
under the following heads ; — 

a. Chemieal Ci>i»/>osi/ioH. — Unorganised bodies arc composed 
of many elements, which may be eilhcr simiile or combined ; 
tnit the combinations are mostly limited to a uniill number of 
elements (fonninu binary and ternary comjiounds), and these 
arc tmited in low combining |]To[>ortioiis. 'llius, carbonate of 
limCf or rx>mmon limestone, k an excellent example of an in- 
organic body,* being a ternary- compound composed of one 
atom of the mctil calcium, three of oxygen, and one of carbon. 

Uiganiscd bodies, on the other hand, arc composed of few 
chemical elements, and these are almost always combined. 
Furthermore, the combioations arc always complex (ternary 
and quaternary compounds), and the elements enter into union 
in high combining propoilions. Finally, the combinations are 
invariably churactensed by the pescDce of water, and are 
prone to spontaneous decomposition. Thus, the great oripinic 
compound, albumen, is composed of 1 44 atoms of carbon, 1 10 
of hydrogen, 18 of nitrogen, j atoms of siOphur, and 41 of 
oxygen. Iron, however, exists in the blood, very prolubly in 
its elemental condition ; and coii|>er has been detected in the 
liver of certain Maminalin, and largely in the red colouring* 
matter oi the fe:ilhers of certain birdt. 

b. Arran^ffunl of Parlf. — Unorganise<! bodies are composed 
of an aggregation of homogeneous parts (when unmixed) which 
bear no dclinite and fixed relations to one another. 

Organised bodies are composed of heterogeneous parts, 'Avt 
relations of which amongst themselves aie more or less definite, 

e. Ivrm. — Unorganised bodies are either of no definite shape 
— when they are said to I>e " amorphous"— or they are crystal- 
line, in which case thev are almost invariably bounded by 
pbnc surlace.1 and slmight lines. Organised bodies arc always 
more or less definite in shape, presenting convex and concave 
sutiices, and being bounded by cun-cd lines. 



I 



in ihe prujicr trnw <>r the (cm ; Mill on^nlMllon 1* \n 

' ' iiT, (hat ilie . 
0.11 ihrimgho^n 



ic j>ru|i 
01 cu 



ludi 1 vM proporlion oi cixt (ht crincumitanl of vitaltl' 
poM b«c in view will be fully !t«n«il by aBunuDg tliAC 
ait tr)^miM, ■»! ill JmJ bodici uc wiMnuKua/. 

* la aaother i«n(e liowitoDe nuy be wid to be orfuiic— iiBinely, when 
It hw been pioiluccd by the openttioni at Hving l>eiii)[t; but thb doet not 
'SiKt the above defiiuikon. 



I 
I 




DEAD AND LIVING BODIES. 



d, J/MrQ^/fiuv^a/^.— ^Vhen unorganiMd bodies increase in 
size, as ayWib do, the increiue is produced Himpl^ by what is 
called "accretion;" that is to say, by the addition of fresh 
particles from the outside. 

Oiganised bodies increase by what is oflcn called (he " in 
ttusasceptioti" of matter; in other words, by the reception of 
matter into their interior and its assimilation there. To this 
pn>ces!t alone vjxn tlie term " growth " be properly applied. 

e. CyelUal CAangt. — Unotttanised bodies exhibit no actions 
that are not piirclir physical or chemical, and they show no 
tendency to periodical vicissitudes. Ofgani^cd bodies arc pre- 
eminently distinguished by the tendency which they show to 
pass through spontaneous and cyclical changes. 

To sun up, all bodies which arc composed of an aggr^- 
(ion of diverse but deliniiely related parts, which have a ddi* 
nite %ha)>e, bounded by cur\-ed lines and presenting concave 
and convcK surCtces, which increase in sixe by the intussus- 
ception of foreign particles, and which pnw through certain 
cyclical changes, are crg-inisnl: and it is with the study of 
bodies such as these that Biology is concerned. 

In the foregoing it haa been o-isumed, for tlie sake of simpli- 
city, tliat all living bodies exhibit organiKation. It is to be 
rcmembeicd, however, that there are living bodies {e.g., Fora- 
miiti/rra) to which the term of " oi^aniscd," as above defined, 
cannot be applied. Such bodies arc lining, but they arc not 
gtgaitisfJ. in these cases the distinction from dead matter de- 
pends wholly upon the mode of grow th, and upon the presence 
of vital activity as shown by the occurrence of various periodic 
changes. 

The grand and fundamental characierH by which living 
bodies are (listiDguishcd from dead bodies are these:— i. Every 
tiding body possesses the power of taking into its interior cer- 
tain foreign materials, and converting these into the substances 
required to build up fresh tissue or repair waste. By this 
power of '■ asaimilation," as it is called, a living body^n»K'j. 
I. Living bodies, a» they are constantly assimilating fresh mat- 
ter, are inceuanily losing portion); of their Mihstance — or, in 
other words. partt:d death is a constant acrompnniment of life. 
J. If our observation be continued for a sufficient length of 
time, we find that cvcrj- living body has tlie power of repro- 
ducing its like. That is to say, every living body has, directly 
or iitdirectly, the power of givmg origin to minute germs which 
are dcvelojKd into the likene» of the parent 4. The matter 
of a living body is subject to the s.ime physical and chemical 
forces as those which affect rfrad nuiitcr: but it is f\ln\^CT vW 



MANtJAL OF ZOOIXIGV. 



seac of somcthine in rina« of which ihe living body can over- 
ride the ph^tcu laws which contn^ all <lc:i<J matter, lite 
living l>ody is the teat of tntrgy, and can oviTcotno the pri- 
mary law or the intrlia of matter. It has certain rcljitioRS 
with the outer world other than those of mere ])assivity. 
However humble it may be, and even if it be pcnuanciilly 
rooted to one place, M>me part or other of every living body 
possesion the power of stwntaneoiu and inde|>endeiit move- 
ment — a power postes*ed by nothing that is dead. 

j. Naturr of Lifk. 

ITe have itcxt to determine — and the question \i one of 
II difficulty — what connection exists between organi-tation 
t life. Is organ i.tation, as we have delincd it, ciwenlial to 
the manifestation of life, or can vital phenomena be exhibited 
by any body whi<;h is devoid of an organised struciurc? In 
other words, is life the Muse of organisation, or the ttsuH of it ? 
And firBI, what do we mean by life 'i 

Life has been variou&ly defined by different writers. Bichat 
<letines it a* "the sum total of the functions which resist death ; " 
Trevininus, as " the constant uniformity of phenomena with 
divereily ofextcmni inliacnccs;" Dugcs, as "ihc-spcria! acti- 
vity of organised bodies; "and Bcclard, as "organisation in 
action." Ali these dciinitions, hoivcvcr, are more or less objec- 
tioDable, since the assumption underlies them all that life is 
tiueunbly connected with organlxation. In point of fact, no 
rifpa delinition of life appears to be at prevent iios^ible, and it 
is best to regard it ns being simply a tendency exhibited by 
certain forms of matter, under certain conditions, to pass 
through a scries of changes in a more or less definite and 
detCTiDtnatc sequence. 

As regards the connection between life and organisation, 
it appears that whilst all organised bodies exhibit this ten- 
dency to change, and are therefore alive, all living beings ar« 
not nccc&iarily organised. Many of the lowest forms of life 
(such as the Foramintfera .imongsl the I'roto/^a) fail to fiillil 
one of the most essential conditions of organis.tlion, being de- 
void of definite [wirts or organs of any kind Nevertheless, they 
are capable of manifestmg all the essential phenomena of life; 
they arc produced from bodies like themselves; they cat, 
digest, and move, and exhibit distinct sensibility to many ex- 
ternal imprcssioiu. Furthermore, many of tliesc little masses 
of structureless jelly possess the power of manufacturing for 
fhcnnselvv^ of time, or of the still more intracUblc flint 



I 



I 

I 



lint, I 




NATURE OF LIFE. 



nttemal shcfls of surpa&sing beauty and mathcmatica! regu- 
larity. In the Eace of these tacU we are tlicrefore compelled 
to come to the conclusion that life h truly the ^utf and not 
Ihc consequence of orgnniration ; or, in otlier words, that or- 
gani&aiion is not an intrinsic and in<li spendable condition of 
vita] phenomena. 

Such an inirinsic and Indispensable condition is, however, 
to be found in the presence of a uniform " physical basis," to 
which has been applied the name of '* protopbism " (the " bio- 
]ilatin " of Dr Beale). Without some Kuch a material substra- 
tum, or medium upon whi<^h to work, no one vital ]>heiiome. 
non can be cxhibilc<l. The ncccoary forces may be there, 
but in the absence of this ncccsuiy vehicle there can be no 
outvrard and visible manirestaiion of their existence. Life, 
tbeiefore. lu nv inow if, and as far as vr know it, may be said 
to be inseparably connected with protoplawn. In other words. 
protoplaxm beats to life the same relation that a conductor does 
to the electric current. It U the sole medium through which 

I Ufc can be brought Into rebiion with the external world. There 
is, however, as yet, no reason to believe that protoplasmic mat- 

I ler holds any other or higher relation to life, or that vital 
phenomena are in any way an inherent property of the matter 

^^S which alone they are capable of being manifested. 

^K^As regards iLt iMture, protoplasm, though capable of form- 

^^ng the most complex structures, does not necessarily exhibit 
an^nhing which can be looked upon as organisation, or dif- 
fcTentintion into distinct parts ; and its chemical composition 
is the only constant which can be approximately slated. It 

\ consists, namely, in all its forms, of the four elements, carbon, 
hydrogen, oxygen, and nitrojjen, united into a proximate 
com(KHmd to whi<;h Mulder applied the name of " protdne," 
and which i« very ncarl/ identical with albumen or white-of- 
tgg. It further appean probable that nil forms of protoplasm 
ou be made to contract by means of elcctricily, and " are 
liable to imdcrgo that peculiar coagulation at a temperature of 
40'" — 50° centigrade, which has been called ' heat-stiffening '" 
(Hux!e>-). 

If we admit, then, with Huxlej' — and the admission re- 
ijttiret aoine qualifications — that "protoplasm, simple or 
Budeaied, is i)m fonTul basis of all life,* there, nevcrthelesB, 

* It hu not ytX. Iiwn ihovrn that the livlni; mRtler which n dnignal* 
I7 Ik oonmiitM term of ' ' piotoplnm " hu univcriAlly nn'l m all <aws 
a ombUM and imdevUllne <hein)c^ oompnNitii^n ; anil ilicic it, inde«d, 
m W hvlkvc thM IhU \* not the aw. It it nlto cciHin \\iU \licte »M 
rHUfHiU «*« eaMrt ok of wliidi we do out at ptdcni Vnow, wYiwii 




MANUAL OF ZOOLOCV. 

KDMin cenain conditions equally indispensable to the external 
numifestation of vital phenomena; though life itself, or the 
power of exhibiting vital phenomena, may he jiresen-ed for a 
longer or shorter [wrioil, even though these conditions be ab- 
sent These tx&mtU conditions of vitality are, firstly, a. cer- 
tain temperature varying from near the free ring- point to i lo' 
or 130°; leemJfy, the presence of water, which enters largely 
into the compoiJtion of all living tissues ; thirdly, tlie presence 
of oxygen in a free state, — tliis, like u-ater, appearing to be a 
iiae i)ua non of life, though certain fungi are suued to offer 
an excepbon to this statement* 

The non-fiilfilmcnl of any of Ihoie conditions for an^ length 
of time, as a rule, causes death, or the cessation of vitality ; but, 
as before remarked, life may sometimes remain in a dormant 
or " potential " condition for an apparently indefinite length of 
time. An excellent illustration of this is afforded by tlie great 
tenacity of life, even under unfavourable conditions, exliibited 
by the ova of some animals and the sceiU of many plants ; but 
a more striking example is 10 be iounA in the Rolifcra, or Whcel- 
animalculcs. These arc minute, mostly microscopic creatures, 
which inhabit almost all our ponds and streams. Diniinutive 
as they are, they are nevertheless, comparatively speaking, of 
a very high grade of organisation. They possea a mouth, 
mtsticatoi^ organs, a stomach, and alimenlnr)- canal, a dis- 
tinct and well -developed nervous system, a differentiated re- 
productive apparatus, and even organs of vision. Repeated 
experiments, however, have sliown the ranarkible fact, that, 
witli tlieir a<|uatic liabits and complex organisation, the Roti- 
feni are capable of submitting to an apparently indefinite de- 
privation of the necessary conditions of their existence, with- 
out thereby losing their vitality. They may be dried and 
reduced to dust, and may be kept in this state for a period of 
many years ; nevertheless, the addition of a little water will 
at any time restore them to their pristine vigour and activity. 
It follows, therefore, that an organism may be deprived of all 
power of manifesting any of the phenomena which constitute 
what we call life, without losing 10 hold upon the vital forces 
which belong to it 

If. in conclusion, it be asked whether the term " vital force" 
is any longer permissible in the mouth of a scientific man, 
the question must, I think, be answered in the affirmative. 

■N ahtolutcly eumtlil to the maiiitmancc of life, probabty eiwn In i|> 
huMbiot mattifaitaliMit; 
' Ktttol expeiinieati, u j* BnconfiimCTl. wonld p> to prove ihui thae 
eoBdititmi of nuUtx arc not of sudi cucntial \tD^n»nc«- 



I 

I 



NATURE OF UFE. 7 

Fonneiljr, no doubt, the progress of science was retsrded and 
its growth checked hy a too exclusive reference of natural 
^tenomena to a so-caltcd viutl forc«. Equally unquestionable 
u the fact that the development of Biological science has pro- 
gressed contemporaneously with the successive victories gained 
by the physicists over the vitali&ts. i^iill, no physicist has 
hitherto succeeded in explaining any fundamental vital phe- 
nomenon upon purely phpical and chemical principles. The 
simplent vita! phenomenon has in it something over and above 
the TDCTdy chcmic^il and physical forces which we can demon- 
strate in the Uborator}*. It is easy, for example, to say that 
the action of the gastric juice is a chemicnl one, and doubt- 
less the discovery of this fact was a great step in physiological 
science. Nevertheless, in spite of the most searching inves- 
tinlions, it b certain that di(;esiion presents phenomena 
much are as yet inexplicable upon any diemical theory. This 
is exemplified in its mmt striking fonn, when we look at a 
■inple organinn like the Amnba. Thn animalmlr, which 1.1 
■tnictttrally little more than a mobile lump of jelly, digcvU a.t 
perfectly — as far as the result to itself is concerned — as does 
the most hifihly organised animal with the most complex 
digestive ap]iar;tius. It takes food into its interior, it digests 
it without the presence of a single organ for the purpose ; and 
Still more, it possesses that inexplicable selective power hy 
which it assimilates out of its food such constituents as it 
needs, whilst it rejects the remainder. Id the present state of 
our knowledge, therefore, we must conclude that even in the 
process of digestion as exhibited in the Amccba there is some- 
thing that is not merely physic^ or chemical Similarly, any 
organism what just dead consists of the same protoplasm as 
bcfbre. in the same forms, and with the same arrangement; 
hat it has most unquestionably lost a something by which all its 
properties and actions were moditicd, and some of them were 
produced. What that something is, we do not know, and 
Mffaaps never shall know ; and it is possible, though highly 
Improbable, that future discoveries may demonstrate that it 
is merely a .subtle m<K]ihcatton of some physical force. In 
the meanwhile, as all viu-il actions exhibit this n)y»tcrious 
something, it woul<l appear un philosophical to ignore its exist- 
ence altogether, and the term " vital force " may therefore be 
retained with advantage. In using this term, however, it 
must not be forgotten that we are simply employing a con- 
venient expression for an unknown quantity, for that residual 
portion of every vital action which cannot at present be tc- 
fcrrcd to the opaatioa of any JinouTi physical force 




MANUAL OF ZOOLOGV. 

DlFFEIteNCES BETWEEN AMUALS AND PLANTS. 

Wv have novr arrived At some definite noiioii of (he essen- 
tial chaniricts of living beings in genera), and wc have next to 
cODsidcr whni arc the characicriaiicK of the t«-o great divisions 
of the organic world. What aic the characters which induce 
us to place any given organism in cither the vegetable or the 
animal kint^om ? What, ia fact, arc the diJTerencet 1>etwcvn 
ttnimalx and plants? 

It in generally admitted that all bodies which exhibit vital 
phenomena arc caijable of beinj^ rcfexred to one of the two 
great kingdoms or organic nature. At the stmc time it is 
often extremely difficult in individual caxes to come to any 
deciMon as to the kingdom to which a given organism s.hould 
be referred, and in many cases the determination is purely 
arbitrary. So strongly, in fact, has this difficulty been' felt, 
that some observers have established an intermediate kingdom, 
a sort nf no-man's-land, for the lecupiion of those debatable 
organisms which cannot be <ielinitely and iionUively classed 
cither amongst vegetables or unoDgst animals. Thus, Dr 
Ernst Hxckcl has proposed to form an intertDcdiatc kingdom, 
which he calls the Htgnuin ProtiUseum, for the reccpiton of nil 
doubtful organisms. Even such a cautious observer as Ur 
KotlcElon, whilst ()uettiontng the projiriety of this step, is 
forced to conclude that "there are organisms which at one 
period of their life exhibit an aggregate of phenomena such as 
to justify lis in speaking of them as animab, whilst at another 
they appear (o be as distinctly vegetable." 

In the case of the btghei animals and plants there ii no 
difficulty; the former being at once distinguished by the 
postetsion of ii ner\*ous system, of motor giower which can be 
vcduntarily cxerri.scd, and of an internal cavity fitted for the 
reception and digestion of solid food. The higher pl.inis. on 
the other hand, possess no ncrvoii* s>'«cm or organs of sense, 
arc incapable ol independent locomotion, and are not provided 
vrith an intcnial digestive cavity, dieir food being wholly fluid 
or gaseous. Tliese distinctions, however, do not hold good as 
Kf^irds the lovrer and less highly organised members of the 
two kingdoms, many animals having no nervous system or in- 
ternal digestive cavity, whilst many plants jiossew the power 
of locomotion ; so that we are rtmipellcd to institute a closer 
comparison in the case of these lower forms of life. 

a. Jvrm.—Ai regards external configuration, of all cltamc- 

tcTs the most obvious, it must be admitted that no alMiohtle 

distiacdoa eati be laid dotvn between plants and animals. 



I 

I 

I 
I 



d 



DIFFXRENCE5 BKTWEEN ANIMALS AN'D PLANTS. 9 

iiay of our ordinary zoophytes, such 3.s the HydroicI Polypes, 
the Ka-«hnil>s iind corals — as, indeed, Ihc nami; xoophyic 
imiilies — arc so simiUr in externa] ap[ie.-ir.-incc to plunts that 
they were long dcserit^ed as such. Amongst the Moliuscoidft, 
the common sca-mal (Flueiu) is invariably rcgaidcd by sea- 
side visitor* as a sea-weed Alany of the Prolojioa arc equally 
like some of the lower plants {FrolophyiaJ; and even at the 
pvesenl day there are not wanliiif: those who look upon the 
qwogcs u bdongin^ to thevcgctoble kingdom, On the other 
hand, the embryonic forms, or "zoospores," of certain un- 
doubted pUnts (such as the Protococeus nivalis, Vauchcria, 
Ice) arc provided witli ciliated processes with which ihcy 
swim about, thus coming so closely to resemble some of the 
Infusoriao animalades ax to have been referred to ll\at divi- 
uon of the I*TOtoioa. 

i. Interval Stnuture. — Here, Again, no line of demarcation 
can be drawn between [he animal nnd vegcLible kingdoms. 
Id this respect all plants and animals arc fund,)mcn(nlly 
similar, being alike composed of molecular, cellular, and lib- 
Tous tiuues. 

e. CAtmUaJ Com/fftilim. — PUnts, speaking generally, exhibit 
a prq>on<lerancc of lemnry compounds of cirbon, hyilrogen, 
and oxygen — such as starch, cellulose, and sugar — whilst 
nitro(;enised compounds enter more largely into the compo- 
sition of animals. Still both kingdoms contain identical or 
representative compounds, though there may be a difference 
in the proportion of these to one another. Moreover, the 
moat characteristic of all vt^tablc comjitiiinds, vii^ cellulose, 
has been delected in the outer covermg of Ihc fica-s(^uirts, 
or Ascidian Molluscs; and the so-called "glycogen," which is 
secreted by the liver of the Mammalia, is closely allied to, if 
not absolutely identical with, Ihc hydratcd starch of plants. As 
a general rule, however, it nuy be stated that the presence in 
any organism of an extemul envelope of cellulose raise:^ a strong 
presumption of il* vtrgctihic nature. In the face, however, 
of Ihc &cls above stalwl, the presence of cellulose cannot be 
looked upon as absolutely conclusive. Another highly rharar- 
teristic vegetable compound is thlorofhyll, the green colounng- 
nuiter of plants. Any organism wliich exhibits chlorophyll 
in any quantity, as a projier element of its tissues, is most 
profaibly vegetable. As in the caie of cellulose, however, the 
presence of chlorophyll cannot be looked U|K>n as a certain 
tcsl, since it occurs normally in certain undoubted animals 
{t^., SUHfor, anvongst the Infusoria, and tlic Hy\lra viridis, 
or tlte gTc«n Vmb-warcr Polype, amongst the C<x}(nterata). 



10 



MANUAL OF HJOtOGY. 



d. Mtt^ Povftr. — This, though broadly distinctive of an! 
mab, can bjr no means be said to be chanictcrislic of them. 
Thus many aninuls in their nulurc condition arc jxrrmancntly 
fixed, or attached to sotnc foreign object ; and the embryos of 
many plants, together with not a few aduh fonns, arc cndoired 
with locoiitoii\'e power by ineaiu of those vtbratile, hair-Uke 
processes which are called "cilia," and are so cfaancleristic 
of many of the low-ei forms of animal hfe. Not only is this 
the case, but large ntitnbcrs of the lower jilants, such as the 
Diatoms and l>esmids, exhibit throughout hfc an amount and 
kind of locomotive power which docs not admit of being rigidly 
S^anucd from the movements executed \>\ animnls, though the 
dosol researches luve hitherto failed to show the mechanism 
whereby these movementi are brought about. 

e. Naitiree/Ihe Awe/. — WhiUt all the preceding points have 
failed to yield a means of invariably separating animals from 
|>laots. a distinction which holds good almost without excc|>- 
tion is to be fotind in the nature of the food taken respectively 
by each, and in the results of the convcr«on of the same. The 
unsatisfactory feature, however, in this distinction is this, that 
cveti if it could be ^wn to be, theoreiicjiUy, invariably trtie, 
it would nevertheless be practically impoMible to a|>ply it to 
the RTcatcT number of thoic minute organisms coDoemiug 
whi<£ alone there can be any dispute. 

As a broad rule, all plants are endowed with the power of 
converting inorganic into organic nutter. thc/fwiaS plants 
consists of the inor^^anic com)M<unds, carbonic add, ammonia, 
and water, alimg with Knull (jiuniiiies of certain mineral salts. 
From these, an<l from these only, plants are capable of elabo- 
rating the protcinBCcou* matter or protopU.sm which consti- 
tute* the )>hysical basb of life Plants, therefore, take as food 
very simple bodies, and manufacture them into much more 
oompjex substances. In other word», by a process of deoxida- 
tion or uobuming, rendered posuble by the infiucnce of sun- 
light only, plants convert the inorganic or stable elements — 
ammonia, carbonic acid, water, and certain mineral salts — into 
the organic or unstable elements of food. The whole problem 
of nutrition ma^ be narrowed to the cgucslion as to the mode* 
ai>d laws by which these stable elements arc raised by the vital 
chcniiatry of the plant to the licight of unstable compounds. 
To this general statement, however, an exception must seem- 
ingly be nude in bvour of certain IHingi, which retjuire organ- 
ised compounds for their nourishment. 

On the nthcr hand, no known snim.il possesses the po«'er 
of cooverting uiojjanic compounds into organic matter, but 



I 



I 



I 



I 



d 



DIFFERENCES BETWEEN ANIMALS AND PLANTS, tl 



1*11, mediately or immediniely, are dependent in this respect 
tlI>on pbnt& All animals, as far as is ccrl.iinl)' known, nxjuin: 
dy-nude protcinaccous matter for the maintcnan<:c of exist- 
{■•ncc, and this ihcy can only obtain in [he first instance from 
plants. Antnuls, in fact, diflcr from pUnls in requiring as food 
complex organic bodies which they ultimately reduce to very 
mudi simpler inoripnic bodies. The nutrition of animals is 
I process of oxidation or burning, and consi.scs essentially in 
ibe converoon of the energy of the food into vital work ; tliis 
coRvenion being effected by ihe passngc of the food into living 
tissue. Plants, therefore, arc the great manufacturers in nature, 
— animals are the great consumers. 

Just, however, as this law does not invariably hold good for 
plants, certain fungi bein^ in this reopect animals, so it is 
not impouibte that a limited exception to the univcnialily ot 
the law will l>e fMiiMi in tJic case of animal* also. Thus, in 
tome recent investigations into the fatmn of the sen at great 
tlepths, a singular organism, of an extremely low ty|)e. but 
occupying large areas of the sea-bottom, has been discovered, 
to which Professor Huxley has given the name of Bathybius. 
As v^etal>lc life u extremely scanty, or is altogether wanting, 
ID these ftbyocs of the ocean, it hat been conjectured tliat 
this organism is possibly endowed with the power — otherwise 
exclusively found in plants— of elaborating organic compounds 
out of inorganic materials, and in tliis way supplying food for 
the higher animals which surround iL The water of the 
ocean, however, at these enormous depths, is richly charged 
with organic matter in solution, antl this conjecture is thereby 
rendered doubtful. 

Be this as it may. there rcnuin to be noticed two distinc* 
tlons, broadly (hough not universally applicable, which arc 
due to the nature of the food required respectively by animab 
and plants. In the first place, ihc food of all plants consists 
partly of gaseous matter and partly of matter held in solution. 
They require, therefore, no .special aperture for its admission, 
and no internal cavity for iu reception. The food n( almost 
all ftniroah consists of solid iiarlicles, and they are therefore 
usually provided with a mouth and a distinct digestive cavity. 
Sooe animals, however, such as the tapeworm and the Ore- 
, live entirely by the imbibition of organic fluids through 
leral surfece of the body, and many have neither a dis- 
Fraoath nor stomach. 

Secondly, plants decompose carbonic acid, retaining the 
''■carbon and setting free the oxygen, ccrwin fungi forming a,t\ 
exception to thishn: The reaction of plants upon the aVmo- 



13 




MANUAL OF ZOOLOCV. 



sph«re is thererore charaLicrUcd by the produclion of fre« 
oxygen. Aninuls, on tlie oiher hand,al»orb oxygen aiu) emit 
cubonic acid, so that their reaction upon the >linoa{>heTe is 
the reverse of that of plants, and n characterised by th« pro- 
duction of caibonic aci<l. 

I-'tnally, it is worthy of notice that it is in their lower and 
not in their higher developments that the two kingdoms of 
organic nature approach one another. No diiBctilty is ex- 
perienced in separating; the higher animals from the higher 
plants, and for tliese univeriu! laws can be laid down to which 
there is no exception. It mighl, nut unnaturatiy, have been 
thought that the lowest classes of animals would exhibit most 
aflinicy to the highest plants, and that thus a gradual p.iss3gc 
between the two kingdoms would be established. This is not 
the case, however. Tlie lower animals are not allied to the 
higher plants, but to the lower ; and it is in the vety lowest roem- 
hm or the vegetable kingdom, or in the embryonic an<l imma> 
lure forms of plants little higher in the scalet that we find such 
a decided animal gift as the power of independent locomotion. 
It is also in the less highly organised and less specialised forms 
of plants that we find the only departures from ihe great laws 
of vegetable life, the deviation being in the direction of the 
laws ^animal life. 



{ 



5. MORPHOLOOV AND PHVSIOLOOV. 

The next point whidi demands notice reUtes to Ihe nahirt 
of the dilfercnces between one animal and anoilier, and the 
question is one of the higlie:st importance. F.very animal — 
as every plant — may be regarded from two totally distinct, 
and, indeed, often apparently opposite, point's of view. From 
the first point of view we liave to look simply to ihc laws, 
form, and arrangement of the tlrtutura of the organism ; in 
short, to its external shape and internal structure. This con- 
stitutes the sdaice of morphology (ni:f>i.form, and }.v/i>f, Jis- 
awne). From the second, we have to .itiidy the viul actions 
performed by living beings and the /imc/wii dixtrharsed b^ the 
diffemit parts of tlic organism. This constitutes the saence 
of physiology, 

A third department of loologj- is concerned with the relations 
of the organi.sm to the external conditions under which it is 
placed, constituting a division of the science to which the term 
*' distribution " is applied. 

Morphi^ogy, again, not only treats of the structure of living 
beiBgs to Oieir /iilly-de^clopcd condition (anatomy), but is 



I 



A 



DIFFERENCES BETWEEN DIFFERENT ANIMALS. I3 

aiso concerned with the changes through which every living 
beiii); has to |>as3 before it assumes its mature or adult charsc- 
tcm (embryology or dcvclopmcni)- The term " histology " ia 
further nnptoyed to designate that branch of morphology which 
is speciAllr oocujned with tlie investigation of minute or micro* 
scopical tissues. 

Physiology treats of all the fiinclions exercised by living 
bodies, or by the various definite parts or organs, of which 
mou animab are composed. All these functions come under 
thne hcaids: — i. Funetiani of Nutritim, divisible into func- 
tion* of abMrption and metaniorjihosiK, compriiinK those func- 
tions which are necesnry for the gron-th and m.iintcnance of 
the organism, 2. Funetiaits ^ R^froiiu^ion. xnhrttby rhc pcr- 
pctiution of the species is secured. 3, l-unctinns of (Sorrtlatioa^ 
comprtsin^; all those functions (such as sensation and voluntary 
motion) by which the external world is brought into relation 
with the organism, and the organism in turn reacts upon the 
external world. 

Of these three, the functions of nutrition and reproduction 
are often collectively called the functions of organic or vege- 
tative life, us. being common to animals and plants ; white the 
functions of conclalion are called the animal functions, as 
being more eJq)ecia!ly characterislic of, though not peculiar to. 
animals. 

6. DiFFEitesces srrwEEN dippehemt .Animals. 

AH the innumerable diScrenccs which subsist between dif- 
ferent animals may be classed under two heads, correxnonding 
to the two aspecu of every living being, morphological and 
physiologiol. One animal differs fr<»m another cither merpho- 
l^taily, in the fun<Iainental [loints of its stntcturc ; or p/iyti». 
lagiaiiJy, in the manner in which the vital functions of the 
organism are discharged. These constitute tlie only modes in 
which any one animal can differ from any other; and ihcymay 
be considered respectively under the heads of Specialisation of 
Function and Morphuloxical type. 

a. ^edalisatun of Funetuti. — AH animals alike, whate^■CT 
Ihei/ stnicttirc nay be, perform the three great ph>-s 10 logical 
Innctions -, that is to say, they all nourish themselves, repro- 
duce their like, and have certain relations with the external 
world. I'hcy differ from one another physio log ir.i I ly in the 
in which these functions are performed. Indeed, it is 
the functions of correlation that it is possible that there 
be any difference in the amount or jierfcclion of the 
ion performed by the organism, since nutrition and Tt^o- 



14 



MANUAL OF ZOOLOCV. 



duclion, as far as their r«sut(3 are concerned, are ewentialljr 
tame in all animnls. In ih« manner, liowevcr, in which 
same results arc brought about, ^at differences arc obscT\-ablc 
in different animals. The mitnlion of siich a simple organism 
as the Amceba is, indeed, performed perfectly, as far aa the 
result to the animal itself is concerned— as perfectly as in the 
case of the highest animal — but it is pcrfonned with the simptest 
possible apparatus. It may, in fact, l>e said to be pcrfoTmod 
yrithoul any tpedai apiKiraius, since any pjirt of ihc :(urlace of 
the body may be exiempori.ied into n mouth, and there is no 
differentiated alimentary cavity. And not only is the nuuiliTe 
apparatus of the simplest character, but the function itself Is 
equally simple, and is entirely divested of those complexities 
and sc]>arations into secondary ftmctions which cliaracterise 
the process in the higher animals. Ii is the same, too, with 
the functions of reproduction and correlation ; but this point 
will be more clearly biouKht out if we examine the method in 
which one of the three primary functions is performed in two 
or three examples. Nutrition, as the simplest of the fimctions, 
will best answer the purpose. 

In tiie simpler Protoeoa, such as the Amccba, the process of 
nutrition consists essentblly in Hie reception of food, its di- 
gestion Vfithin the body, the excretion of effete or indigestible 
matter, and the distribution of the nutritive fluid through the 
body. ITie first three portions of this process arc effected with- 
out any special organs for the purjjose, and for the last there is 
simply- a rudimentary contractile cavity. RespiratiOD, if it can 
l>e said to exist at all as a distinct funaion, is simply ejected 
by the general surlace of the body. 

In a Ccelcntcrate animal, such as a sea-anemone, the func- 
tion of nutrition has not advanced much in com^iJexity, but 
the means for its performance are somewhat more specialised. 
Permanent organs of prehension (tentacles) are present, there 
is a distinct mouth, and there is a persistent internal cavity for 
the reception of tlie food; but this is not shut off from the 
general cavity of the body, and there are no distinct circubtory 
or re9]>iratory organs. 

In a Mollusc, such as the o^ter, nutrition is a much more 
complicated prwcM. There is a distinct mouth, and nn ali- 
mentary can.-il which is shut off from the general cavity of the 
body, and is provided with a separate aperture for the excre- 
tion of effete and indigestible mailers. Digestion is performed 
by a distinct stomach with accessory glands ; a special contrac- 
tile cavity, or heart, is provided for the propulsion of the nutri 
live /voducts kA digestion through all parts of the organi 



1 

the ■ 

the ■ 
1.1 .< ^ 



I 
1 



organism, ■ 



DtPFERENCES BETWEEN DIFFERENT ANIMALS. I5 

and Ok function of mpirstion is perfonncd by complex organs 
specisiiy adapted for the purpose 

It ia not neccssaiy here to follow out this comparison 
further. In still h^her animals the function of niitrilioa 
hccomes still further hrokeii up into secondary functions, for 
the due pcrfiinnaDce of whidi special ot]{ans are provided, the 
complcxit)' of the organism thus netesKirily tncrea.sing fari 
fafiu wiih ihc complexity of the function. This gradual sul> 
divisioQ and elaboration is carried out equally wiih the other 
Iwo phj^iological functions — vie., reproduction and corrcbtioo 
^4nd It constitutes what is technically called the " specialisa- 
tion of functions," though il hsu been tnore happily termed by 
Milne- Ed wnnls " the i>rincit>le of the phj-siologicai division of 
labour." It is nee<lleM, however, to remark that in the higher 
aainula it is the functions of correlation which become most 
b^bljr specialised — disproportionately so. indeed, when com- 
pared with the development of the nutritive and reproductive 
fiuictioDS. 

>. J/frfitfygiea/ lypt. — The first point in which one 
animal may differ from another is the degree to which the 
principle of t)ie i^iysiolojj^cat division of labour is carried. 
The second point in which one animal may differ from another 
ia in its " morphological type ;" that is to say, in the fun<U- 
mental pUn upon which it is constructed. By one not specially 
acqiuinled with the subject it might be readily iniogincd that 
ettcfa species or kind of animal iras constructed upon a plan 
peculiar to itself and not shared by aay other. I'his, how- 
ever, is £ir from being the case ; and it is now universally 
rco^iscd that all llic varied species of animals — however 
great the apparent amount of diversity amongst ihcni— may be 
amnged tuMer no more than half-a-doien primary morpho- 
togical types or plans of structure. Upon one or other of 
these five or six plans every known animal, whether living or 
extinct, i» constructed. It follows from the limited number of 
primitive types or patterns, that {jreat ntimbers of animals 
mutt agree with one another in their morphological type. It 
follows aXw that all so agreeing can differ from one another 
only in the sole remaining element of the question — namely, 
by the amount of specialisation of function which they exhibit. 
Every animal, therefore, as Professor Huxley has well expressed 
it, is the resultant of two icndcncies, tlie tmc morphological, 
the other physiological. 

The six types or plant of structure, upon one or other of 
which all known animals have been con&lTuclcd. are techni- 
cally called "sub-kingdoms," and arc knovm by the luxne^ 




MANUAL OF ZOOLOGY. 

Protozoa, Coctcntcratii, Annuloida, Annulosa, Mollusca, and 
Vcrlcbrata. Wc have, then, lo remember that every member 
of each of these priniaQ- diviuons of the anima! kingdom 
ape«s with every other member of the same divi.iioii in beinn 
fonne<) upon a certain definite plan or type of .sinicciin:, antl 
differs from evetr other simply in the grade of iu organisation, 
or in other words, in the degree to which it exhibits specialisa- 
tion of function. 

Von Baer's Law of Development. — As thcst\idy of living 
beings in their adult condition shows us ihat the differences 
between those which are consirucled upon the same moipho- 
logiical type depend upon t)ie degree to which specialinlion 
of function is carried, so the study of <levcloi>raent tcichcs 
us that (he changes imdeigone by an^ animal in passing from 
the embryonic to the mature condition arc due to the same 
cause. AH the members of any given sub-kingdom, when 
examined in Ihcir earliest embryonic condition, arc found to 
present the same fundamental characters. As development 
)>roceeds, however, they diverge from one another with greater 
or less rapidity, until t)ie adults ultimately herome more or 
less different, the range of jiowible modification being ap- 
parently almost illimitable. The differences are due to the 
different degrees of specialisation of function necessary to 
perfect the adult ; and therefore, as Von Baer put it, tkt pro- 
grtss ^ da-4li>pmeni h/rom tk< gmfral to the tfftaal. 

It is upon a misconception of the true import of this law 
that the theory arose, that every animal in its development 
pasi^cil through n seric:s ofsLiges in which it resembles, in turn, 
the different inferior members of the animal scale. With 
regard to man. standing at the lop of the whole animal 
kingdom, this theory has been expressed as follows ; — " Human 
oi^ganogenesis is a ttansiior>- comparative anatomy, as, in its 
turn, comparative anatomy is a fixed and permanent state of 
the OT^nogeneait of man" (Sencs). In other words, the 
embryo of a Vertebrate animal wns believed to pass through a 
series of changes corresponding respectively to the permanent 
types of the loner sub-kingdoms — namely, the Protosoa, Cct- 
lentcrata, Annuloida. Annulosa, and Mollusca — before finally 
assuming the true vertebrate dianclers. Such, however, is 
not truly the case. The ovum of every animal is from the 
first impressed with the power of developing in one direction 
onl)r, and ver^- vaily exhibits the fundamental characters ivofwr 
to its sub-kingdom, never presenting the structural peculi- 
arities belonging to any other morphological type. Never- 
Ihdas, the differences which subsist between the members 



1 



crs of M 



^. 



HOMOLOGV, ANALOGV, AND HOMOMORPIUSM. I7 



^ 



<ich stib-kingilom in ihdr ndult condition are tnily referable 
to the clirgTi.*c to which development proceeds, the place of 
c2ch individual in his own siib-kingdom being regulated by the 
stage ai which itcvtlopnicnt is anc«cd. Thus, many cases 
arc known in whicli (he younger stages of a given animal 
rrfrewtl the ]>erinanent adult condition of an animal !>ome- 
what lower in the Male. '\'o give a single example, the young 
GaMerot>ntl (aniungtt the Molluxci) transiently ]>rvsents all Ihe 
esMntiu characters which permanently distinguish the adult 
Pleropod. The development of the Gasteropod, however, pro- 
oeeds beyond this point, and the adult is much more highly 
spectilised than b tJic adult Pleropod. 



7. HoHOLoav, Akauxiy, ano Homomorpiiism. 



When organs in different animals agree with one another in 
fundamental ttruOure, they arc said to be "homologous;" 
when they peiform the same functions they are »aid to be 
** anatogous." Thui the wing of a bird and Ihe arm of a man 
are constructed upon the Kime fundamental plan, and they 
are therefore homologous organi>. They arc not analogous, 
however, since ihey do not perform the same function, the 
one being adapted for aerial locomotion, the other being an 
organ ct prehension. On the other hand, the wings of a bird 
and the wings of an insect both serve for fliglit. and thej' arc 
therefore anakgoiu, since they perform the same funciioo. 
They are not homologous, however, as they are constructed 
upon wholly disiimUar plans. There are numerous cases, 
however, in which organs correspond willi one another both 
uructurally and functionally, in which case they are both 

imologous and analo^ou^ 

A form of homology is often seen in a singleanimal in which 

ere exists a succession of parts which are fundamentally 
identical in sirxiclurc, but are variously modified to fulfil dif- 
Eerent functions. Thus a Crustacean — such as the lobster — 
may be looked U]>on as being composed of a succession of 
linpf each of which bears a pair of a(>|)cndage», these appen 
dagies being constnicied upon the same tyjK, and being there- 
fore homologous. The)- arc, however, variously modilieil in 
different regions of the body to enable them to fulfil special 
ftmctioofi, some being adapted for swimming, others for walk- 
ing. oUters for prehension, others for mastication, and so on. 
'liiii ftucccssion of fundamentally similar pans in the same 
aniiml constitutes what is known as serial h{>molosy- When, 
however, the successive pans are similar (o one aitoihct, bolV 

K 



urucii 

Kmol 
AC 
ere 



l8 



MANUAL OF ZOOLOGY. 



in structure and in function, th« case heoomes rather one 
what is called " vegetative " or " irrelative rq)etition. " An ex- 
cellent instance of this is seen in the common Milli|>c<le (lultuL 
Jfym4>«w/A urn. —Many cumplcs occur, both among animals 
and among plants, in which fJunilics widely removed from one 
another as to their fundamental structure, nevertheless pre- 
sent a singular, and sometimes extremely close, resemblance 
in iheir external characteis. Thus the composite Hydroid 
I'olypcs an<l the Polyton are singularly like one anoihex— ■ 
■■" much KO, that they have often been classed together ; ' 
ercas, in reality, they belong to different $iil>-kingdonu. 
lany other cases of this resemblance of different animjda 
might be adduced, and in many cases these "representative 
forms" appear to be able to fill cadi other's places in the 
gencial economy of nature. This is so far true, at any rate, 
that " homomorphous " forms are generally found in different 
parts of the earth's surface: Thus, the place of the Cacti 
of South America is taken by the Euphorbia: of Africa ; or, 
to Uke a zoological illustration, many of the dilTerent orders 
of Mammalia are rrprtstnteii in the single order Marsupialia 
in Australia, in which countrj- this order has almost alone 10 
discharge the functions elsewhere performed by sc%-eral orders. 
Many homomorphous fonns, however, live peacefully side by 
side, and it is difficult to say whether in this case the resem. 
blance between them is for the advantage or for the disadvan. 
tage of either. In other cases we find cerUin animals putting 
on the external characters of certain other animals, to which 
they may be closely related, or fix)m which they may be widely 
separated in loological position. Such cases are said to be ex- 
amples of "mimicry," and such animals are said to be " mim- 
etic." Excellent examples of this may be found amongst 
certain Butterflies, or in the close resemblance of the clear- 
winged Moths to Bees and Hornets. In all these case^ it 
appears that the mimetic species is protected from some enemy 
by its outward similarity to the form whii-li it mimics. Finalty, 
there are numerous ciscs in which animals mimic certain 
nature objects, and thus greatly diminiiih their chances of 
being detected by their natural foes. Excellent instances of 
this arc afforded by the insects known as Walking-leaves {Phyi- 
lium) and Walking-sticks {Ptmamidie), which respectively 
present the most singular resemblance to leaves and dried 
twigs, 

8. Correlation or Growth. 
This tctxa is employed by zoologists to express the empU 



I 

I 



CLASSIFICATION. I9 



^ncU law, that cettam itniclures, not necessarily or usunJIir 
' connccicd rogctlwr by any visible link, invariably occur in 
utociation with one another, and never occur apart, — so far, 
at any rate, u human observation goes. 

Tliu!), all animals which possess two condyles on (he occi- 
|>iial bone, and ixMsess non-nucleated red bIoo<l-corj>ti.icles, 
suckle their yoang. Why an animal with only one condyk 
on its ocripiUl bone should not suckle its young we do not 
know, and perhaps we shnll at some future time find mam- 
mar)' glands associated «-ith a single occipit^ condyle. Again, 
the feet arc cleft in all animals which ruminate, but not in 
any other. In other cases the correlation is even more appa- 
rently lawlcM. and is even amusing. Thus all, or almost all, 
cats which are entirely white and have blue eyes, are ^t the 
same lime deaf. With regard to the.se and similar gene- 
ralisaiions we must, however, bear in mind the following 
three points : — 

I. The various parts of the ot^ntsaiion of any animal are 
■o closely interconnect ed, and so mutually dependent upon 
one another, both in their growth and development, that the 
cfaancters of each must be in tarn relation to the characters 
of all the rest, whether this be obviously the case or not. 

a. It is rarely possible to assign any reason for correlations 
of smicturc, though they are certainly in no case accidental. 

5. The taw is a purely empirical one, and expresses nothing 
more than the result of experience ; so that structures which 
wc now only know as occurring in association, may ultimately 
be found dissociated, and conjoined with other structures of a 
ditTcrent diaracler. 

9. Cl-^SSIPICATIOK. 

QacciAcation is the arranf^ment of a number of diverse 
objects into lai^er or smaller groups, acconling a.'( they ex- 
hibit more or lc« likrness to one another. The excellence of 
any given cla-wiftcation will de[)cnd upon the namic of the 
pomts which are taken as determining the resemblance. Sys- 
letDi of dassihcation, in which the groups are founded upon 
mere external and superiicial points of similarity, though 
atwa usefiil in the earlier stages of science, are always found 
in the long-run to be inaccurate. It is needless, in fact, 10 
point out that many living beings, the structure of which is 
fundamentally ditferont. may ncverthetc» present such an 
aiDOUOt of adapti^'e external resemblance to one another, that 
they would be grouped together in any "artificial" classift- 
cation. Thus, to take a sing}e cxamjjJe, the whalt^ by v\s 





MANUAL OF ZOOUKiV. 



extirmnl t^hancten, would certainly be (grouped amongst the 
fifhci, thuiigh widd}' rcowvet! from thcni in all the CMcntial 
t>oinis of its structure. " Nnturil " xjrstciDX oC cUuttiftcatioiLM 
on (he other hxnd, endeavour to arrange anitnals into d(vi^| 
sions founded upon s due coDsidention of a// the essential 
and fundamental points of structure, wholly incspeciivc of 
CKicmal simikrity of form and habits. I'hilosophicat classili- 
cation depends upon a due appreciation of what constitute 
the true pcnnis of difference and likeness amongst animals ; 
and ire have already teen that these are tnoriiltoiofcical typ^ 
and spe<:ialiution of fun<:tion. Philoaoi>liicu cla.'uiiication 
therefore, is a formal expression of the facts and laws 
Morphology and Physiology. It follows that the more liillii 
the programme of a philosophical and strictly natural classiD 
cation can be carried oui, the more completely doc* it affo 
a condensed expo^lion of the fundamental construction of 
objects clasnficd. Thus, if the whale were placed by an 
ficial grouping amongst the fuhes, this would xiinply expres 
the facts that its habits are a<iu3tic and its boily (kh-like 
When, on the contrary, wc obtain a natural clavsili cation, and 
wc Icam thai the whale is placed amongst the Mammalia, wc 
then know at once that the young whale is bom in a compa- 
raiivt'ly hetples* condition, and that its mother i& |>Tovided, 
with special nummary glamh for its support ; tlii.t expresxing 
a fundamental dittinciion from all fishei. and being associate 
with olher equally eucnttal correlations of siruclure. 

The entire animal kingdom is primarily divided into some^ 
half-a-dozen great plans of structure, the divisions thus formed 
being called *' sub-lungdoros." Tlie sub-kingdoms arc, in lura, 
broken up into classes, classes into orders, wlcrs into families, 
&milies into genera, and genera into s|fecies. We shall examine 
these stMxessivel^, commencing with the consideration of a 
species, since this is the zoological unit of which the larger 
divisions are made up. 

SfiM/y. — No term is more difficult to define than "species," 
and on no point arc lootogists more divided than as lo what 
should be understood by thi.i word. Naturalists, in fact, arc 
not yet agreed as to whether the term s)>ecies expresses a real 
and permanent distinction, or whether it is to be regarded 
merely ,ik a convenient, but not immutable, abstraction, the 
cmploT^nent of which is necessitated by the requirements o( 
classification. 

By Buffon, " speciea" is defined as " a constant succes:tion of 

individuals* similar to and capable of reproducing each other." 

* la uiing the lena "indU-idDol," It ratal be botnc in nilud thai the 



led 

anafl 

tcS 



A 



CLASSmCATlON. 



21 



Dc Candollc defines species as an assemblage of all those 
individuals which resemble each other more than they do 
othera, and are able to rc|>Toduce their like, doing so by the 
generative process, and in Mich a m-nnncr that they niuy be 
SBpposcd by analogy to have all descended fiom a sin({Ic being 
or a single juir. 

M. dc Quntrcfagcs defines species as " an assemblage of 
individuals, more or leu rc&cmbling one another, which are de- 
scended, or may be regarded as being descended, (rom a single 
primitive pair by an unintenuplcd succession of familtcs." 

Miiller delino s]>eciet as " a living Totn), re|>reiicnied by in- 
dividual iKringK, which reap|>ears in the product of generation 
with certain invariable iharaclers, and is constantly repro- 
duced by the gcnemivc act of similar individuols." 

Accoixting to Woodward, " all the specimens, or individuals, 
which are so much alike that we may reasonably believe them 
to have descended from a common siock, constitute a speties" 

From the altove dclinilions it will be at once evident that 
there arc two leading ideas in the minds of loologists when 
tbey employ the teim tpedcKi one of these being a certain 
anoont of resemblance between individuals, and tlic other 
being the proof that the individuals so resembling each other 
have descended Trom a single pair, or IVom paint exacdy :simi- 
lar to one another. 'I'hc chat^ictcrx in wliich in<li vidua Is must 
resemble one another in onkr to eniitle chcra to be grouped 
in a se[>aralc sjK'cics. according to Agassii, "arc only those 
determining siic, proportion, colour, habits, and relations to 
surrounding circumstances and external objects." 

On a closer examination, however, it will be found that 
tbeae two leading ideas in the definition of species — external 
reMmbUnce and community of descent — are both defective, 
aixl liable to break down if rigidly applied. I'hus, there are 
in mture no assemblages of plants or animals, ustulty grouped 
together into a single s])ecies, the individuals of which exattly 
resemble one anoiher in e^'ery point. Kvcty naturalist is 
compelled to .idmii that the individuals which compose any 
s»callcd species, whether of plants or animals, differ from 
one another to a greater or less extent, and in respects which 
may be regarded as more or leis impotlant. I'hc existence 
of sach individual differences is attested by the imivcrsal 
enptoymeni of the tenns "variclies" and "races." Thus a 
"rariety" comprises all those individuals which possess some 

"(oolopcal imliiridasr' is mtant i that ii to ny. the total mull of the 
Jw J opnwt <f a ii^lc ovum, u will be hetcoiUr cxptmned st ncUn 



23 



MANUAL OF ZOOLOGV. 



n 



di*tinctiv« peailiaiity- in common, Inil do not differ in other 
respects from anolher set of individiLiU Huflicicnlly to entitle 
them to take rank as n scpantc spccic-s. A " race." again, is 
simply a pcrmancni or " pcrpetiuUcd" variety. The question, 
howc\'cr, is this — How far may these differences amongst in- 
dividuals obtain without necessitating their bcin^ placed in a 
separate species ? In other wordi : How gnu a the amount 
of individual difference which is to he considered as merely 
" jfariflal" and at what exact jioint do these difTercnceK lieconie 
of "sfect/Se" value ? To this ijucstion no answer can be given, 
since it depends entirely upon the weight which dinercnl 
naturalists would attach to any given individual difference.* 
Distinctions which appear to one observer as suflicicntly great 
to entitle the individuals possessing them to be grouped as a 
distinct species, by another are looked upon as sunply of 
rarietid value; and, in tlie nature of the case, it seems mii>os- 
sible to lay down any dciinttc rule*. To such an extent do 
individual differences sometimes exist in pariiadir genera^ 
termed " protean " or " polymorphic " genera — that the deter- 
mination of the different species and vaiictics becomes an 
almost hopeless task. 

Besides the individual differences which ordinarily occur 
in all specie*, other cmcx occur in which a species consists 
normally and regularly of two or even three distinct forms, 
which cannot be said to be mere varieties, since no inter- 
mediate forms can be discovered. When two such distinct 
forms exist, the species is said to be " dimorphic," and when 
three arc present, it is called " trimorphic" Thus, in dimorphic 
plants a single species is composed of tvo distinct forms, 
similar to one another in all respects except in their repro- 
ductive oreant, tlie one form having a long pistil and short 
stamens, me other a short pistil with long stamens. In tri- 
morphic plants, the species is com|>o«ed of three *uch distinct 
fomis, which differ in like manner m the conformation of their 
reproductive organs, though they are otherwise undistinguish- 
able. — (Dam-in.} Similar cases are known in animals, but in 
them the differences, though apparently connected with repro- 
duction, arc not conhned to the reproductive organs. Thus 
the females of certain butterflies normally ap[>ear under tw> or 
three entirely different forms, not connected t>y any intermediate 
links; and the same thing occurs in tome of the Crustacea. 

* Ai an example <tl Ihlfc i( I* anftdtnc lo tilludc to the fact (hat hardlf 
May two baianiUs agree as to the numbei of ipecita of Wiltowt ind Bnin- 
bts in ihe OrJIbh bl««. What one oUtciret clotaa u mere ruielM^ 
anoticf r^-ardi aa goad and diulnct ipecJo. 



I 
I 

1 



I 





regsrds, thercrorc, the first point in the definition of 
species — namely, tlie external reaeublance of &sseiubla^e& of 
tndividualit — we are fonied to conclude that no two individuab 
are exactly alike ; and that the amount an^J kind nf external 
reMnilibnce which constitiitc:( a species is not a precise and 
invariable i]iiantity, but dq>cnds upon the value attached to 
poniculnr charactcre by any given observer. 

The second point in the definition of species — namely, com- 
munity of descent — is hantly in a more ealisfaclory condition, 
since the descent of any given series of individuals from a 
sinnle pair, or from pairs exactly similar to one anoiher, is at 
best but a probatulity, and is in no case capable of proof. In 
the case of the hi{(her nnimaU it can doubtless be shown that 
certain aaembbges of individuals possess amongst themselves 
the power of fecundation and of producing fertile progeny, 
and that this power docs not extend to the fecundation of in- 
dividuals belonjijng to another different assemblage. Amongst 
Um higher animals, " crot^ei " or " hybdds " can only be pro- 
duced between closely-allied species, and when jkroduced 
tfaey arc sterile, and are not c.i[Kibte of reproducing their like. 
In these cases, therefore, we may take this as a most satis- 
bctory element in the deilinition of "species." The sterility, 
however, of hybrids is not universal, even amongst the higher 
animals ; and amongst plants no doubt can be entertained but 
that the imtividuali of species universally admitted to lie dis- 
tinct are capable of mutual fertilisation ; the hybrid |>rogeny 
thus produced being likewise fertile, and capable of reproduc- 
ing similar individwds. I'hat this fertility is often irregular, 
and may be destroyetl in a few generations, admits of ex^na- 
lion. and hardly altera the signilicancc of these undoubted facts. 

Upon the whole, then, it seems in the meanwhile safest to 
adopt a definition of species nhich implies no theory, and 
docs not include ihe belief tliat the term necessarily expresses 
a fixed and pennaneiit quantity. S]iecies, therefore, may be 
defined as an atstmNaxe of indh'iduah ifhich resembit each ether 
im tkdr estmtia/ (haratleri, are abU, dirediy (v indirttUy, to firo- 
iau ftrtile mdrvidttatt, and K'kUk do net {oi far at human ob- 
ttrv^tioH goet) giM rite to indifiduaJs whuh jitry from Iht 
pneral type lArougk autre /Ann (ertain definite limilt. The pro- 
duction of occasHmal monstrosities does not, of course, in- 
validate this definition. 

Gentti is a term applied to groups of species which po<3css 
a cooUDunity of essential details of structure. A genus may 
include a singk species only, in cases where the combination 
of characters which make up die S|)ectes are to peculiai x\i3.X 



24 



MANUAL OF ZOOLOGY. 



no other species exhibits similar stmctuni chaiactcnt ; or, on 
the other hand, it may contain many hundreds otsnedes. 

J'amUkt are groups of gcnem which agree in their ^n«nil 
choractera. According to Agassiz, they arc divisions founded 
upon peculiarities of " form as determined by smiciurc." 

Orders arc groups of bmilies related to one another by 
structural charactera common to all. 

Chita are larger division*, coin])risiiig animals which are 
formed iijwn the tame fiindnmenu! j)lan of structure, but differ 
ill the method in which the plan is executed (Agassii). 

Siii^-ii'igdcms are the primary divisions of the aniiiul king- 
dom, which include all those animals which are formed upon 
llic sime structural or morphological type, irrespective of the 
degree to which specialisation of function may be carried. 

Im/N>siibUity c/ a Lituor Clatii^atieu. — It has sometimes 
been thought thztt t)ie animal kingdom can be arranged in a 
linear serivs, every memlier of the seriex being higher in point 
of organisation than the one below it. As we have seen, How- 
ever, the lialus of any given animal depends upon two condi- 
tions^-onc its morph^ogical type, the other the degree to 
which &])ecialisation of function is carried. Now, if wc take 
two animals, one of which bdongs to a lower morphological 
type titan the other, no degree of specialisation of function, 
however great, will place the former above the latter, as far as 
itK lyf< cf striulure n concerned, though it may make the 
former a more highly organised animal. Every Vertebrate 
animal, for example, belongs to a higher morphological tyj 
than every Mollusc ; but the higher Molluscs, such as cu 
fishes, arc much more highly organised, as Ear as their type 
concerned, than are the lowest Vcrtcbrata. In a linear classi- 
fication, therefore, the cuttle-fishes should be pbccd atKn'c the 
lowest fishes — such as the lanceiet — in j^pite of the fact that 
the type u)>on which the latter are constructed is by far the 
highest of the two. 

It is obviguK, therefore, that a linear classification is not 
ptMSible, since the higher members of each nib-kingdom are 
mote highly cn^nised than the lower forms of the next sub- 
kingdom in the scries, at the same time that they are con- 
structed upon a lower morphological type. 




10. Repkodvctiuh. 



Reproduction is the process whereby new individuals 
genentcd and the perpetuation of the species insured. The 
netbods in which this end may be att.-iined exhibit a good 



an I 
rhe 1 



deal of diversity, but they may be all considered under two 
heads. 

I. Sexual Rtprodtution. — This consists essentially in the 
production of two distinct elements, a germ-cell or ovum, and 
a spenn-ccll or spcrmiUoxoid, by the conuict of which the 
o^-um — now said to be "fccundnlcd" — it enabled to develop 
itself into a new individual. As a rule, the gcrm-ccll is pro- 
duced by one individual (female) and the spermatic clement 
by another (ruIc) ; in wliich case the scxe* arc said to be dis- 
tinct, and the spedti is said to be "dicecioux" In other 
cases the same individual has the power of jiroducing both the 
essential dcrocnlK of reiiniduoiion ; in uhicli uise the sexes 
arc said to be united, and the individual is said to be "hcr- 
nuphroditc," " androgynous," or " moncecioos." In the case 
ofbennaphrodite animals, however, self-fecundation — contrary 
to what might have been expected — rarely constitutes the re- 
productive procetis ; and, as a rule, the reciprocal union of two 
such indivi<luals is necessary for the production of young. 
tA'cn amongst hermaphrodite plants, wlicic self-feamdation 
may. am) certainly does, occur, provisions seem to exist by 
whtdt perpetual sdf-fcnilisation is prevented, and the influence 
of another individual secured at intervals. Amongst the 
higher animals sexual reproduction is the only process whereby 
new individuals can be generated. 

II. Noit-stxual R(pri)dHtlii>ti. — .\mongst Ihe lower animals 
, beings may be produced without the contact of an ovum 
, a spermaloioid ; that is to .iny. without any Inic gcncTalivc 
CL The processes by which this is ciTcctcd vaty in different 
Js, and are all spoken of as forma of " asexual " or 
"agamic" reproduction. As wc shall see, however, the true 
' individual " is very rarely produced otherwise than sexually, 
ad nKist forms of agamic reproduction are really modifica- 
tions of gro«-th. 

a, Gtmmaiion and Fhtion. — Gemmation, or budding, con- 
in the production of a bud, or buits, generally from the 
lerior, but Komclimcs from the interior, of the body of an 
[animal, which buds arc developed into independent beings, 
[which may or may not remain permanently attached to the 
[parent organism. Fission differs from geniraation solely in 
[ihe (act that the new suuctures in the fomier case are pro- 
iduced by a division of the body of the orij^inal organism mto 
[•cpa/atc parts, which may remain in connection, or may iinder- 
[go detachment. 

The timi>lcst form of gemmation, perhaps, is seen in the 
power possessed by cenain animals of reproducing puU ot 



36 



MANUAL OF ZOOLOGY. 



Ihdr txtdies whidi they may have lost Thus, the Crustacea 
poMC» lite power of rc|>roducing: a lost Itmb, by means of a 
bud which is gradually det-etoped till it as^iumet (he form and 
Ulcci the place of the missing inenil>er. In these <:ascs. how- 
ever, the i)roces» is not in any way generative, and the pro- 
duct of gemmation can in no sense be spoken of as a distinct 
being (ox looid). 

Another form of gemmation may be exemplified by what 
talccs place in the Foraminifcra, one of the claues of the 
Protozoa. The primitive form of a Foratninifer is simjily a 
little sphere of sarcode, which has the power of secreting frt)Ri 
its outer surface a calcareous envelope ; and this condition 
may be permanently letainerl (at in Ijigena). In other cases 
a process of budding or gemmation takes place, and the prim- 
itive mass of sarcode [woduccs from itself, on one side, a 
second mass ciucily simiUr to the first, which does not detach 
itself from its parent, but remains permanently connected with 
it. This second mass repeats the process of gemmation as 
befOT^ and this goes on — «)I the segments remaming attached 
to one another — imtil a bwly is jirudueed, which consists of 
a number of little spheres of s.-irn>de in organic connection 
with one another, and surrounded by a shell, often of the 
most complicated description. In this case, however, the 
l>uds produced by the primitive spherule arc not only not 
detached, but they can only remotely be regarded as independ- 
ent b«ngs. "niey are, in all respects, identical with the [mm- 
ordial segment, and it is rather a case of " vegetative " repeti- 
tion of similar ports. 

Another form of gemmation is exhibited in such an organ- 
ism as the common sea-mat (Fhiitra), which is a composite 
organism composed of a multitude of similar beings, each of 
which inhabits a little chamber, or cell ; the whole fovming a 
stnicttire not unlike a sea-weed in appearance, l^is colony is 
produced by gemmation from a single primitive being f" |X>ly- 
pide"), which throws out buds, each of which repents the pro- 
cess, apparently almost indefinitely. All the buds remain in 
contact and connected with one another, but each is, ncvcrthc-; 
less, a distinct and independent being, capable of performing 
all the functions of life. In this case, therefore, each one of 
the innumemble buds becomes an independent being, similar 
tOt though not detached from, the organism which gave it 
Urth. This is an instance of what is called " continuous gem- 
mation." 

In other cases — as in the common freshwater polype or 
Jfydta — the buds which arc thrown out by the i>rimitivc or- 



n 



I 



REPRODUCTION. 



27 



ganism become developed into creatures exactly resembling 
the pireni, but, instead of remaining perroaiieiiily attached, 
and thus giving lise to a compound oiganiHm, tliey are de- 
tached to lead an entirely indci>cnd«nt existence. 'ITiis is a 
sinple inwtance of what is termed " ditcondnuous gemmation." 

The method and results of fission may be regaidcd as e^sca- 
tially the umc as in the case of gctnmation. The products of 
the division of the body of the primitive organism may eiiher 
Rtnain undelachcd, when they will give Ti:<>e to a com|>caite 
unicture (as in many corals), or they may be thrown on and 
live an independent existence (as in some of tlic Mydtozoa), 

We are novr in a postion to understand whni is meant, 
■trictly speaking, by the term "individual." In zoological lan- 
guage, an wdiviiiual is ddincd as "rqualie the total rtiuit of 
tht devtiopnunt cf a tingk n-um." Amongst the higher animals 
there is no difficulty about this, for each ovum gives rise to no 
more than one single being, which is incapat>le of repeating it- 
self in any other way than by the production of another ovum ; 
so that an individual is a single animal. It is most import- 
ant, however, to comjjrehend tliat this is not necessarily or 
always the case. In such an organism as the sea-mat, the 
ovum gives rise to a primitive polypidc, which repeal), itself by 
a process of continuous gemmation until an entire colony is 
produced, each member of which is independent of iis fellows, 
and is capable of producing ova. In such a case, therefore, 
the terra " individual ° must be applied to the entire colony, 
since lhi« is the result of the development of a single ovum. 
The separate beings which compose the colony arc technically 
called " rooids." In like manner the Hydra, which produces 
fresh and independent Hydra: by discontinuous gemmation, is 
not an " individual,'' but is a zooid. Here the xouids are not 
pennaoenily united to one another, and tlie "individual" Hydra 
consists really of the primitive Hydra, f/us all the detached 
Hydix to which it gave rise. In this case, therefore, the "indi- 
ridual " is composed of a number of disconnected and wholly 
faidepeDdcni beings, all of which arc the result of the develop- 
ment oTa single ovum. It is to be remembered that both the 
parent zooid and the " produced zodids " are capable of giving 
rise to fresh Hydrse by a true generative process. It must 
alto be bomc in mind that this production of fresh zooids by a 
pro ce ss of gemmation is not so essentially ilifferent to tlic true 
tcxnal process of reprtiduction as might at Arsl sight appear, 
since the ovum itself may be reganlud merely as a highly spe- 
cialised bud. In the Hydra, in fact, where the osiim is pro- 
duced as an external process of the wall of the body, ihu UV^ 



38 



MANUAL OF ZOOLOGY. 



ne»s is extremely striking. Tlie ovarian bn<l, however, diflen 
Iroin the trtic i;L-mmii: ur liudt in it« innbility to develop itself 
into nn indepcndL-nt orgnni^m, itntess previously btoiighl into 
coDiaci with another special gcntraiive clement. The only 
cxceptioDS to this statement arc in tiie rare cases of true " par- 
tlienogenesis," to be subscqucnlly alluded ca 

A Reprodtutien by Iitternai Gemmalien. — Before contidering 
the j>henomena of " alternate ceneratiom," it will be sih n-cit to 
gUnec for a moment al a [)c«:ulinr form of (jemmalion exhi- 
bited by some of the Polyzoa, which in in some rexpects in- 
tCTmedinle between ordinary discontinuous gemmation and 
alternation of gencrationj. llicsc organisms are nearly allied 
to the sea-mat, already spoken of. and, like it, can reproduce 
themselves by continuous gcininaiion (forming colonies), by a 
iTue sexual process, and rarely by Assion. In addition to all 
these meihod« iher can reproduce theinselve* by the formation 
of jiecutiai internal buds, which are called "statoblasts." These 
buds are dcvcloiied upon a i)cculiar coni, which crosses the 
body-c;ivity. and is attached at one end to the fundus of the 
itonuich. When mature they drop otf from this cord, and He 
loose in the cavity of the body, whence they are liberated on 
the 4JeatIi of the {>arent organism. When tlius liberated, the 
Etatoblast, after a longer or shorter period, ni|)turc« and give* 
exit to a young Polyzoon, which hax cKcntialty the same 
structure as the adult. It is, however, simple, and has to 
undergo a process of continuous gemmation before it can 
assume the compound form proper to the adult. 

As regards the nature of these singular bodies, "the in- 
variable absence of germinal vesicle and germinal spot, and 
their never exhibiting the phenomena of yelk-deavage, inde- 
pendently of the conclusive &cl that true ova and ovary occur 
elsewhere in the same individual, are quite decisive against 
their being cgg^ ^Ve must then look upon them as gftmet 
peculiarly encysted, and <lcstined to remain for a period in a 
quiescent or pupa-like state." — (Allman.) 

<. AUernalion of GnKratimt. — In the case of the Hydra snd 
the tea-tnat. which we have considered above, fresh eooids 
are produced by a primordial organism by gemmation; the 
being* thus produced (as well as the parent) being capable 
not only of repeating the gemmi[>arou.t jn-ocesx, but also of 
producing new individuals by a inie generative act. We 
have now to consider a much more comple* seric<i of pheno- 
mena, in which the organism which is developed from the 
primitive ovum produces by gemmation h*<o sets of xooids, one 
oT wkkh is desliluEc of sexual organs, and is capable of per- 




ALTERNATION OF GENERATIONS. 

fonninft no other function thui that of nutrition, whilst th« 
oitier IS provided with reproductive orgatis, and is destined 
for the perpeiuiilion of the upecio. In the fomier case the 
produced raoids all resembled cnch other, ant] the parent 
organism which gave rise lo them ; in (he latter ca.ie, the pro- 
duced zooids arc often uitcily unlike cnch other and unlike the 
^H^tarent, since their functions arc entirely different. 
^Hr The stin|>lesi form of tlie process is seen in certain of the 
^HHjrdroid Polypes, s>iieh as Senularia. The ovum of Sctru- 
^Hjaria is a free-invinuning cihated body, which, after a short 
^Bloco«notive existence, attaches itself to some Kubm.irine object, 
^V'derelops a mouth and tentacles, and commences to pro- 
duce xooids bkc itself by a process of continuous gemmation. 
These remain permanently attached to one another, with the 
result that a compound orfjanism is produced, consisting of a 
^_ Dtunber of io<iid!^ or " |>olypites," organically connected to- 
^H.fclber, but enjoying an independent existence. None of the 
^^ luoids. however, are provided with sexual organs ; and though 
there is tlicorciically no limit to the si»e which the <:olony may 
fcaich by gctnm.ition. its buds arc not detached, and tbi; 
specks would therefore die out, unless some special provision 
were lUaile for it* {jraertation. Besides these nutiilivc 
lOOtda, however, other buds are I)r0(lu<-ed which <lifl'er con- 
ndenbly in apjiearance frnm the former, vind whi<:h have the 
power of generating the essential elements «f reproduction. 
TlkMC generative zoitids derive their nouiishment from the 
materials collcrlcd by the nutritive zooids, but only live until 
ihc ova arc matured in tlicir interior and liberated, when 
they disappear. The ova thus produced become fix^swim- 
roing dliatcd bodies, such as the one with which the cycle 
began. 

In this case, therefore, the "individual" Sertularia con- 
^H>ists of a scries of nutritive xobids, collectively called the 
^H " Iruphosomc," and another scries of reproductive xooids, c«l- 
^Blcctively called the " gonosome," the entire scries often rcmain- 
^^ing in organic connection. 

In other forms nearly allied to Sertularia (such as Coryne) 
the iwoccss advances a step further. In Coryne the genera- 
tive buds, or xooids, do not produce the reproductive ele- 
ments U long as they remain atlarJied to the parent colony ; 
bat tbcy rc<)uire a preliminary period of indejiendent exist- 
ence. For this i>Hr[Ki.se they are specially organised, and 
when sufficiently matured they arc detached from' the 
ttaiionafy colony. The generative zodid now appears as an 
entirely iiMlependcnt bein^, described as a species of j<:V\'j-^!>Vv 



30 




MANUAL OF ZOOLOGY. 



(or Medusa) under the name of Sarsia. It consists of a bell- 
shaped dUc, by means of which it is enabled to swim freely ; 
from the centre of this disc depends a nutritive process, with 
a mouth and di(;cstive caviiy, whereby the oripmisin is able to 
increase considerably in sixe. Tlie substance of tlie disc is 

ticnciiated by ;i complex system of canals, and from its ma^n 
langs a scries of tentacular processes. Af^er a period of inde- 
pendent locomotive existence, the Medusa attains its fiill 
growth, when it develops ova and spcrmaiozoa. Ity the con- 
tact of these cmbrj'os arc produced ; but these, instead of 
resembling the jelly-fish by which they were immediately gene- 
rated, proceed lo develop thenuelves into the fixed Hydroid 
colony by which the Minlusa was originally produced. 

Still more extraordinary (^enomena have been discovered 
in other Hydroxoo, as in many of the Lucemarido. In 
these the ovum gives ri.se (ns in Semibria) to a locomotive 
ciliated body, which ultimately fixes itself, becomes trumpet- 
sh^cd, and develops a mouth and tentacles at its expanded 
extremity, when it is known as the "hydra-tuba," from its 
resemblance to the freshwater polype, or Hydra. The hydra- 
tuba has the iwvrer of mutliptving itself by gcmnuition, and 
it can produce large colonics m this wny ; but it does not 
obtain the power of generating the essential elements of 
reproduction. Under certain circumsianccs. hoiii'c%'er, the 
h^dra-taba enlarges, and, after a series of preliminar)- changes, 
divides by transverse fission into a number of segments, each 
of which becomes deUched and swims away. Thc^ liberated 
seffmenls of the tittle hydra-tuba (it is about half an inch in 
height) now live as entirely independent beings, which were 
described by naturalists as distinct animals, and were called 
Kphyrsc They arc provided with a swimming ■ bell, or 
" umbrella," by means of which they propel themselves through 
the water, and with a mouth and digestive cavity. They 
now lead an active life, feeding c^igcrly, and attaining in some 
instances a perfectly astonisliing size (the Medusoids of sonw 
snedes are several feet in circumference). After a while 
they develop the essential elements of reproduction, and 
after the fecundation and liberation of their oia they die. 
The ova, honever, axe not developed into the frcc-swimming 
aiul comiurativcly gigantic jclly-lish bjr which (hey were 
immediately produced, but into the mmute, fixed, sexiest 
hydra-tuba. 

We thus sec that a small, sexless zo(>id, which is capable of 
multiplyittg itself by gemination, produces] by fission several 
imiepcmient locomotive beings, which are cajjable of nourish- 



I 



PARTHENOGENESIS. 



31 



ing thcinsdvcs aixl of perfonning all the Tunctiont of liTe. In 
these arc produced generative elements, which give rise by 
their dcvdopmcDt to the little Axed cicatuK with which the 
series began. 

To the group of phenomena of which the above are example*, 
the name " alternation of generations " o-as applied by Stccn- 
stnip ; but the name ix not an appropnate one, since the 
process ix truly an allem^ition of generation with gemmation 
or fiasioo. The only generative act takes place in the rcpro- 
dnctire zooid, and the production of this from the nutritive 
tooid is a proce^^s of gemmation or fission, and not a pro- 
cess of gcncraiion. The " individual," in (act, in all these 
oats, must be looked upon as a double being composed of two 
bcton; both of which lead more or less completely inde* 
pendent lives, the one being devoted to nutrition, the other to 
reproduction. The generative being, however, i^ in many 
cases not ai fim able to mature the sexual elements, and is 
therefore provided with the means necessary for its growth 
and Qourishmcni aa an independent organism. It must also 
be remembered that the nutritive lialf of the " individual " is 
nanaliy, and the generative half sometimes, aim/i>uW— that is 
to say, composed of a number of »ooids produced by <:on- 
tinuous gemmation ; so that the loologiral individual in these 
cases becomes an extremely complex being. 

These phenomena of so-called " aUcm^inon of generations," 
or " mctagetiesis," occur in their most striking form amongst 
the Hydroxoa ; but they occur also Amongst many of the intes- 
tinal worms (Kntozoa), and amongst some of the Tunicata 
(MoUuscoida). 

d. J'arfiemfmmt. — "Parthenogenesis" is the term employed 
to designate certain singular jihenomena, resulting in the 
production of new individuals by virgin females without the 
mtcrvcniion of a male: By Professor Owen, who first cm- 
ployed the term, parthenogenesis is applied also to the 
processes of gemmation and 6ssion, as exliibited in sexless 
beings or in virgin females ; but it seems bevi to conuder 
Ibese phenomena se|>arately. Strictly, tlie term partlienogcnekis 
ought to be confined to tlie production ttf new individuals 
bom virgin females by means of o!it, which arc enabled to 
develop themselves withuut the contact of the male element. 
The dithculty in this dctinilion is found in framing an exact 
definition of an o^'um, such as will distinguish it from an in- 
ternal gemma or bud. No body, however, should be called 
an "ovum" which does not exhibit a germinal vesicle and 
germinal spot, and which does not enhiUit the phenomenon 



32 



MANUAL OF ZOOLOGY. 



knott-n M segmratation of the ^Ifc. Moreover, ova are almost 
invariably prodiicc<l by a spcirial organ, or ovary, 

A% examples of p.iHhcnogcncsis we may ukc what occurs in 
plant-lice (Aphides) and in the honcy-bcc ; bui it will be seen 
that in neither of these cases are the phenomena ao unequiv- 
ocal, or so well ascenaincd, as to justify a positive assertion 
that they arc inilv referable lo parthenogenesis in the above 
restricted sense of the term. 

The Aphides, or pbnt-lice, which arc so commonly (bund 
parasitic upon pbntS) arc seen towards the close of autumn to 
consist of male and jcmale individuals. By ihc scxuat union 
of these true ova are produced, which remain dormant through 
the H-intcr. Al the approach of spring these ova arc hatched ; 
but instead of KiviiiiC birth to a number of males and females, 
all the young are of one kind, variously regarded as neuters, 
virgin fenuitei, or hermaphrodites. Whatever their true nature 
*iiiy be, Ihese individuals produce riviparcufly a. brood of 
young which resemble themselves; and this second generation, 
in like manner, produces a third, — and so ihe process may be 
repeated, for as many as ten or more generations, throughout 
tlie summer. When the autumn comes on, however, the vivi- 
parous Aphides produce — in exactly the same manner — a final 
brood; but this, instead of being composed entirely of similar 
in<tivi<tit.n1s, is made up of males and females, Sexual union 
now ukcs place, and ova are produced and fecundated in the 
ordinary manner. 

The bodies Irom which the young of the viviparous Aphides 
arc produced are vaiiously regarded as internal buds, as " pseud- 
ova" (/>., as bodies inteirnediate between buds aud ova), and 
as true ova. 

Without entering into deuils, it is obvious that there is only 
one explanation of these ])henomena which will ju.itify us in 
regarding the case of the viviparous Aj>hide* as one of true 
putheoogenesis, as alwvc defined. If, namely, the s]>ring 
broods are true females, and the bodies which ihcy produce in 
their interior are true ova. then the case is one of genuine par- 
thenoseneiis, for there are certainly no males. The case might 
iilill be called one of [urthenogenesia, even though the tiodies 
from which these broods are produced be regarded as internal 
buds, or as " pnemlova ;" for a Irve ovum is essentially a bml. 
If, however, Balhiani be right, aitd the vivi]>arou« A{>lii<te:i arc 
really hermaphrodite, then, of course, the phenomena arc of a 
much ieas abnormal character, 

In the second case of alleged parthenogenesis which we are 
about to examine — namely, in tlie honey-bee — the phenomena 




which have been described cannot be said lo be wholly free 
from doubt. A hive of ben consists of Uiree classes of indivi- 
duals — I. A "<|u«ii," or fertile female; a. The "workers," which 
form the bulk of the communit}', and are really undeveloped 
or nerik> females ; and, 3. The " drones," or males, which are 
only produced at certain limes of the year. We have here 
three distinct seu of lieinf;s, all of which proceed fiom a xin^e 
fertile individual, and the (juotion arise.i, In what manner an 
ihtf ditTcrcniies Wtwecn these produced? At a certain period 
of the year the queen leaves the hive, accomiwnied by the 
droiKS (or males), and takes what is known as her "nuptial 
fiight" through the air. In this flight she is impregnated by 
the males, and it is iiiunaterial whether tliis act occurs once in 
the hfc of the queen, or several times, as asserted by some. 
Be this as it may, the queen, in virtue of this single imfiiegna- 
don, is enal>led 10 tiro«]uce fresh individuals for a lengthened 
period, the semen of the males being stored up in a receptacle 
which communicates by a lube with the oviduct, from which it 
can be shut off at will. The ova which arc to produce workers 
(imdcvdopcd females) and queens (fertile females) are fertil- 
ised on their pasu(;e through the oviduct, the semen being 
allowed to e:tca]>e into the oviduct for tills purpose. The sub- 
sequent <lcvcloj>ment of these feciindateil o\^ Into workers or 
aneens dejieods entirely upon the form of the cell into which 
le ovum IS placed, and upon the nature of the food which is 
supplied to the larvx So far there is no doubt as lo the nature 
of tJic phenomena which arc observed. It is asserted, how- 
ever, by DKicrzon and Sicbold, that the mates or drones are 
produced by the queen from ova which she does not allow to 
come into contact with the semen as they pa%s through the 
oviduct. This assertion is supported bv the fact that if the 
conntinication between the rcccinacle for the semen and the 
oviduct be cut off, the queen will produce nothing but males. 
Also, in crosses between the common honey-bee and the Ligu- 
lias bee, the queens and workers alone exhibit any intermediate 
characters tietwccn the two forms, the drones presenting the un- 
mixed characters of tlie ({ueen by whom they were produced. 

If these obscnatlons are to be ac<repted as established— and, 
upon the whole, there can be no hesitation in accepting them 
as in the main correct — then the drones are produced by a true 
jwDceas of panhcnogcncsis ; but some observers maintain that 
the devdopaieat of any given ovum into 3 drone is really due 
— •• in the cam of the queens and workers — to the special cir- 
aanttances UDder whidi the larva is brought up.* 
* Is the Euc «f /Wati CaiUiv, Voa SieboJd ippein to have graved 




MANUAL OF ZOOLOGY. 



Th«re are various other cases in which paiihcnof^cncRs n 
said to occur, but the above will suffice to intiicuii: ilic };eneral 
character of the i>henom«na in question. The (Awria of [ur- 
thenogeneviK nppcar to be loo complex to be intro<luce<I here ; 
and thcTC is the lets to r^ret in their omission, as nnturalists 
have not yet definitely adopted any one explanation of the 
phenomena to the exclusion of the rest 

/7rj/ Law of Quatrtfagti. — From ihc phenomena of asexual 
reproduction in all its forms, M. dc QuiitTefages has deduced 
the following generalisation ; — 

" TIte formation of new individuals may take place, in some 
instances, by gemmation from, or division of, the lureni-being : 
but tliiK iirorcKs is an exhaustive one, and cannot be carried 
out indefinitely. When, therefore, it is necessary to insure the 
continuance of the species, the sexes must present ihcmseli-es, 
and the germ and sperm must be allowed to come id contact 
writh one another." 

It should be added tliat the act of sexual reproduction, 
though it insures the |)eq>eiuuiioi) of the spetks, i» icry de- 
structive lo the life of the indn'i<ia<tl. The foniution of the 
essential elcmenls of reproduction appears to be one of the 
highest physiological acts of which the organism is capable, 
and it is attended with a corresponding strain upon the vital 
energies. In no case is this more strikingly exliibitcd than in 
the majority of insects, which i^ass the greater portion of their 
existence in a sexually immature condition, and die almost 
immediately after they have become sexually jwrfect, and 
have consummated the act whereby the peq)ecuation of the 
apecics is secured. 



rs (rt 



II. Devei.opme.nt, Tkanspormatiok, and Metamorphos: 

DtvdopmenI is the general tenn .ipptied to all thasc chai 
which a germ undergoes before it assumes the characters 
the perfect individual ; and the chief differences which arc ob- 
served in the process as it occurs in different animals consists 
simply in the extent to which these changes ate external und 
visible, or are more or less completely concealed from view. 
For these diflerences the terms " transformaiion " anti " nieU- 
moTfthoris " are employed ; but they muit be regarded as essen- 
tblly nothing more than variations of <lcvclopment. 

heyond raasonabtc doubt lh>i thr malm srs produced by ii promw nf par- 
l>)rnocFnir*iv XjusAavk, howavn, utcrlt thai the v|*ci of IntKti mie of no 
Ki, ihai lex it only developed in the lam iDer i)i Fmereenoe frMn ihe 
tqs, and thai in each individMal larva the icx ii. dclerininM wholly by the 
nalwc of the food upon which It \% brought up i ■buadant nounthmeal 
/vodaoliv ftnatn^ aiH scaBiiy diet g^vine hm (o xaaXe*. 



A 



DEVEI/JPMENT. 



35 



P 

^H 7yans/«rmaiion is the lenn eropJoyed by QuAtrdiaseit to de- 
j^Blpuie "the series of changes wliich every germ undergoes in 
mchuig the embrvoni<: condition ; those which wc observe in 
evcff creature still within the egg ; those, finally, which (he 
■peaes Iwm in an imperfectly developed sutc present in the 
coonc of their external life." 

Mttamorfh^U is defined by the same author as includmg 
the alterations which are " undergone after exclusion from the 
fgg, and which alter extensively the general form and mode of 
life of the indivitlual." 

Thouf^h b^- no means faultlcxs, these tenns ore sufficiently 
convenient, if it be remembered that ihey arc merely modili- 
cations of development, and express differences of degree and 
not of kind. An insect, such as a buticrfly, is the best illus- 
tratioD of what is meant by tliesc tcnns. All the changes 
which are undergone by a butterlty in parsing from tlie fe- 
Ctindatetl ovum to tlie cundilion of an iuugu, nr perfect insect, 
constitute its deteiapment. 'ITie egg which ix l.iiil by a butter- 
lly undcTgocf a series of changes which eventuate in its giv- 
ing birth to a catCfpUUr, these preliminary changes constitut- 
ing its tratuftrmatuH. l*he cater|jillar grows rapidly, and 
after aevenl changes of skin becomes quiescent, when it is 
known m a " chryuli*." It remains for a longer or shorter 
lime iti this quicsccnl and apimrently dead condition, during 
which period developmental changes arc going on rapidly in 
its interior. Finally, the chrj-s^Iis r\iptures, and there escapes 
from it ti>e perfect winged insect To these changes the term 
mttamerfkMts is ri^lly applied. These changes, however, do 
not ditTer in kind from the clianges undergone by a Mammal ; 
die difference l>eing that in tlie case of a Mammal tlie ovum i.1 
retained within t)ie body of the parent, where it undergoes 
the oocessary developmental changes, so that at birth it has 
little to do but gro«-, in order to be converted into the adult 
antnuL 

From these considersiions we arrive at the second law laid 
down by Quatrefages : — " Those creatures whose ova— ow ing to 
an insufficient supply of nutritioita contents, and an inca]>uci(y 
on the l>srt of the mother to jtrovide for tlieir coniptete de- 
TcU^uncnt wnthin her own substance — are rapidl)' hatched, 

S've bifth to imgwrfcct of&pring, which, in pn)cc«dmg to their 
:jinilive characters, undergo several alterations in structure 
and foriD, known as metamorphoses." 
KanmaJe Drvthpmtnt. — Ordinarily speaking, the course 
1 of dcTClopuMnt is an ascending one, and the adult is tnotv 



36 



MANUAL OF ZOOLOCV. 



iheie is an apparent reversal of this law. and the adult i« to 
all appearance a degraded fonn when compared vrilh the 
cmbiyo. 'ITiis phenomenon is known as "retrograde" or 
" recurrent " development ; and well-marked instances are found 
amongst the Cirripedia and Lcnix», both of which bi^ong to 
the Cnistacea. 

Thus, in the Cim'pedcs {acorn -shells, &c,) and in the 
parasitic Lcma»c the embryo is free-swimming and provided 
with or^pins of vision and sensation, bein^ in most reitpecu 
similar to the pennanent condition of ceruun other Crustacea, 
sxich as the Copepods. The adiilt, however, in both cases, is 
dcgndcd into a nturc or lest completely sedentary animal, 
mora or less entirely deprived of organs of sense, an<t leading 
an almost vegetative life. As a compensation, leiiroductive 
organs are developed in the adult, and it is in this ret peCl, 
superior to the locomotive, but sexless, larva. 



plied V 



II. Spontaneous Generation, 

Spontaneous or K^tiit-ocal generation is the term applicdl 
to the alleged production of living beings without the pre- 
existence of genns of any kind, and therefore without the 
prc-existence of parent organisms. The <iuestion is one which 
has been lonf; and clocKly dt*puie<l, an<l U far from being 
settle^] ; so that it will be sufficient to indicate the facts upon 
which the theory rests. 

If an anim.il or vegetable substance be soaked in hot or] 
cold water, so as to make an organic infusion, and if thlv in-T 
fusion be exposed for a sufficient length of time to the air, the] 
following scries of changes is usually observed : — 

I. At the end of a longer or shorter time, there forms upoaJ 
the surface of the inAaion a tliin scum, or pellicle, which,J 
when examined micnMcopicalty, h found to onnxist of an in-j 
calculable number of extremely minute molecules. 

1. In the next stage these molecules api>ear, many of them,) 
to have increaKed in size by endogenous division, till they fonnj 
short sLitT-shaped fihments, called " bacteria." These increase ' 
in ler^cth by the un>e process until we get long filamentous 
liodicK produced, which arc tenned "vibnonea."* Both the ^ 
bacteria and the vibrios now exiiibat a vibratile or serpentine ■ 
movement through the surrounding fluid. 

J. After a varying period, the oacteria and vibrios become 

* Ry acmr authoriliM it ■> l>elie*«l thai ih« bicieria arv pruducrd hy the 
f«tion lofcthtr of the primilive molcculci in lv<» and thrcci i tad tint Ihe 
vibrio* are produced oal of the haclcria by ihe sddlljon of fre«b molecule 
AftArextrcxnilittafthelUtti, or l>7 their unuioc wWi one another. 



loleculsfl 

J 



SPONTANEOUS GENERATION. 



17 



and tliaintegratc so as to produce again a finely 
molecular pellicle. 

4. Little BphcrioU bodies now appear, each of which is 
provided witli a vibntile ciHuin with which it moves actively 
through the infusion. (Moii-ts lcn».) 

5. Varied Tornis of cilinictl Inrnsoria — some which possess 
a DMMJth and ore othenrise highly oigatusetl — make their 
appearaDce in the fluid. 

The above is the general sequence of the phenomena which 
have been observed, and the following are the two theories 
which have been advanced to account for them : — 

a. By the advocate* of !t|Kintaneoii!i generation, «r " Hetero- 
geny," it is affirmed that the Infu^u^La, which fin-illy appear in 
the inliision, are produced .li^tontaneously out of the molecular 
pellicle, the molecules of which are also of spontaneous origin, 
and ore nut derived from any pre-emting germs. 

i. Hy the " j>ansi>ermists,'' or the opponents of spontaneous 
generation, it is alleged, on the other hand, that the produc- 
twn of Bacteria, Vibrios, Monads, and Infusoria, in organic 
iofitsions, is due simply to the fact that the atmoiiihere, and 
probably the fluid iiielf, is durjred with innumerable germs — 
100 minute. [lerhaiM, to be always delectable by the microscope 
—which, otttaining access to the fluid, and finding there favour- 
able conditions, arc descloped into living beings. 

A large number of elaborate experiments have been carried 
out to prove that atmospheric air is absolutely necessary for 
the production of these living beings, and that if the air be 
properly purified by passage through <le3tructive chemical 
reagents, no such organi*ms will be jiroduced, provided that 
the infusion have been previously boiled. As the reiiults of 
all these experimental trials have hitherto proved more or less 
contradictor}', it is unnecessary to enter into the question 
farther, and it will be sufficient to indicate the following general 
consi<lerat)ons : — 

a. The primary molecules whidi appear In the fluid are ex- 
ircincly minute, and if they are developed from germs, these 
may be so small as to elude any ]>ower of the microscope yet 
known to 111. As they su)ue<|uently become converted into 
bscteria and vibrios, and as there con be little dispute as to 
these being truly living organisms, we are obliged lo believe 
thai they must have nad teme definite origin. It appeare, 
howercr, to be hardly philosophical to assume that they form 
themselves out of the inorganic materials of the indi-sion ; since 
thb implies the sudden appearance, or creation, of new force, 
for which there seems to be no meam of accounting. 



39 



MANUAL OK ZOOLOGY. 



i. The nattire of th« vibrios and bacteria muxt t>e looked 
upon as i|uitc uncertain. To say the teasi of it, they arc qiiite 
as likely to be plants us animals ; a^id the most probable hypo- 
thesis would place the former near the filamentous Confcrvjc, 
or woul<l n-gaid thinn as the mycelium of various apccics 
Moulds {FmiaHium). 

c. What has becD said above with regard to the origin oi 
the bacteria and vibrios applies ciiiially to tlie orixin of the 
Monads, which appear in die infu&ion subseiiumtly to the 
death of the vibrios. 

J. These Moniids, as shon-n by recent researches, arc pro- 
bably to be looked upon as (he embryonic, or larval, forms of 
the higher Infusoria which succeed them. 

t. Ktany of the Infusoria which finally appear are of a. 
comparatively high grade of organisation, beii^ certainly the 
highest of the Proioiioa, and being placed by some comiietent 
observers in tlie neighbourhood of the Trematode Wormj) 
(Annuloida). It is therefore very unlikely that tliese should 
be generated sponL-uieouitly ; »ince, if tliis ever occurs, it is 
reasonable to supj>ose that the creatures thus produced vriM 
be of the lowest possible organisation {such as the Crcgarinids 
or the Moncr3,for example), and will be far below the Infusoria 
in point of structure. 

/ The reproductive process in many of the.te same Infusorin 
is perfectly well known, and it consi.ttn either in a true .texual 
process, for which proper oigans are {irovided (as in J'aramcc- 
cinm}, or in a process of gemmation or fission. It is there- 
fore miprobabk- that they should be gcncratcil in the manner 
maintained by the hetcrogenists. since this mode of reproduc- 
tion would appear to be superfluous. 

g. In the absence of any direct proof to the contrary, it is 
safer to adopt an explanation of the obseTve<l phenomena 
which does not have recourse to bws witli which we arc as 

!'el unac<]uainted. I'hus, it is not at variance with any known 
aw to su]>pose t)ut the primary molecules arc the result of 
the dcvdoproent of germs which find in the inorganic infu&ion 
a suitaUe nidus; that these primary' molecules and the vibrios 
which they produce arc referable to the Protophyia. and 
should probably be placed near the filamentous Conferve; 
that by the death of these vegetable organisms the fluid is 
prepared for the reception and development of the germs of 
the Proto/.oa. for which the fonner serve as fahtlum; and 
that many of the fomu; which are obscn'cd are the larval 
Itagesof the higher Infusoria.* 
* Rfcmi r«K«rch«, etp«ci>lty thoM of Ur Banian, have amhiidied 



I 
I 



ORIGIN OF SPECIES. 



39 



13. Okioih or Species. 

It is impossiMc here to do more than merely indicate in the 
briefest mannt-r tlic two fomUmcntal ideas nliirh arc at the 
bottom of all the various theories as to the ori^n of species. 
The opinions of scientific men arc still divided ujxjn this sub- 
jeci ; and it will be sufficient to give an outline of the two 
leading; theories, without adducing stay of the reasoning upoQ 
which they are based. 

I. Doctrine oj ^ttial Creatian.^On this doctrine of the 
origin of species it is bclie%-e<) tlut spedes are iinmutiiblc pro- 
dactions, each of which has been specially created at some 
pcnnt vrilhin the area in which we now find it, to meet the ex- 
ternal conditions there prevailing, subsequently spreading from 
this spot as for as the conditions of life were suitable for it. 

I J. DMtrine 0/ Da'elapment. — On the other hand, it is be- 
beved thfti Kpecies are not permanent and immutable, but that 
Ihey " uniIer);o modifieaiion. and thai the existing forms of life 
■re ihc descendants by true gcncraliun of preexisting forms." 
— (Darwin.) 

On Lamarck's theory of the development of species, Ibe 
oeant of nmdilicadon were ascribed to the action of external 
[Aysical BKencies, the inter-breeding of already existing forms, 
and the cnects of habit. 

The doctrine of the development of (pccies by variation and 

ton* new ficti » to the pouibility of llclerojnny, liut (hey on by no 
mwin b* hU 10 hare Killed Ibe quotlon, if oiiiy upon Ihe cround that 
;bey iH|ilira oonCniultoii by other eipcilm«nUL)Uu, Tlie cliier hct wlilcli 
tffotn 10 bkvc bMH ctutifldied upon » tolerably firm buii 'a, Ihsl living 
hi my\ I. venUble or animal, imy make their appearanee in organic info- 
•ioiM wUdi hare been lubjecleci 10 a tcmpemturF of contiilctably over 
iht liiillln lllltlll even though the nid infusions have been hcrmcticsl ty 
tobd fai a Auk ftcan which all atmoiplicnc air hu bren pFcitoiuty vnO\- 
tewn. The <klef deduction nhUb appean to flow (ram thl»— auaminK 
iti comeniww — b, ihat tlicfe are tow or|[anlun« whii:h cui exi»l, for s 
entM tarth nf time *l any rate, with an eimmelT tmnll amount of air 1 
fct il b to oe rerneinlxTcd that the proituclion of a iheoreticatly perfccl 
ncnosi h probably piadieally impOMible, If it were noncnlcd. in fact, 
thai a |>GrJccl vicinun iaJ been formrd in the cipenmcnii in question, the 
wl* rMnlt wonU be AM we should have to alter al! our belied ai 10 Ihe 
«a«dtliuni nndei atilch life it a pouibility. The only (angible teiull of 
ttcM eaperiOMBta, m> far, it. that any bu|ipotocl " pre-gutlenl |{«tn» " nnul 
hne been contaioinl, it pment at all, in the iiihnilCTinial portion of air 
stkh Gontd not t>e expelled from Ihc tiatks etperiinaited on ; or, they 
nuut have been able 10 withstaod wiilioul injury a lempFraliire of over 
III* Neitller of these hypolhete* i* nhollv increvtiblc ; tnil Ihe (lucMiun 
oariu to b« ici^ided a* Kill W fudttt. uuf there \i er»c doubt at to the 
MHfaBlty and aconkcy of the expenmentt above alluded to. 



40 




MANUAL OF ZOOLOGY. 



natuml selection — propounded by Daru-in, and commonty 
known as tlic Darwinian ihooty — is based upon the following 
rundamenlal propositions : — 

1. The progeny of all species of animals and phnts exhibit 
vnnAtions amonnt themselves in all pans of their organisa- 
tion ; no two individuab being exactly alike. In other wordi, 
in cvciy spccivs the indivitluaiK tend by vanalion to diverge 
from the parent-type, in some jiarticular or other. 

a. These variations can be transmitted to fiit\iri- generations 
under certain definite and discoverable laws of inheritance. 

3. By artificial selection and breeding from individuab pos- 
sessing any particular variation, man, in successive generations, 
can pioduce a breed in which the variation is permanent ; the 
races thus produced being often as widely oiflerent as arf 
distinct 5i>ecies of wi!<l animals. 

4. The world in which all living beings arc placed is one 
not absolutely unchanging, but is liable to subject them to very 
varying conditions. 

5- All animals and plants give rise to more numerous young 
ilian can by any possibility be prcscn-cd. 

6. As these young are none of them exactly alike, a jvoccss 
of " Natural Selection " will en.iue, whereby those individuals 
which possess any variation favourable to the peculiarities of 
the life of the species will be preserved. Those individuals 
which do not possess such a favourable variation will be placed 
at 3 disadvantage in the "struggle for existence," and will tend 
to be gradually cMcnninated. 

7. Other conditions remaining the same, the tndi\-iduals 
survive in the struggle for existence will transmit the 
DOS, to which their preservation is due, to future ge»6- 

8. Uy a repetition of this ]>roc«ts " varieties " are first cstiib- 
Itshcd ; these bc<^ome permanent, and " races " arc produced ; 
finally, in the lapse of time, the differences become sutficicntly 
great to constitute distinct species. 

14. DlSTKIBUTtOM. 

Under this head come all the facts which are concerned with 
the external or objective relations of animals^that is to say, 
their relation* to the external conditions in which they arc 
placed. 

The gMgrafi^ieal distribution of animals is concerned with 
the deicrmioation of the areas within i«hich every species of 
animal b at the present day confined. Some species are foui>d 
aIn>ost everjwhere, when they arc said to be " coomopolitan;" 



I 
I 



DISTRIBUTION. 



4" 




bui, u a ful«, each species is confined lo a limited and definite 
area. Not only arc species limiicd in iheir dihlribution, but it 
is |>oaiibk lo divide the globe into a certain iiiiniber of ueo- 
graphical regions or " zoolof^cal provinces," each of wlii<ii in 
characterised by the occurrence in itoT certain nssocialcd forms 
of animal life. It b to be remembered, however, that the 
tootoeical provinces of the present day by no means corrc- 
•pond with those of former periods, and thai ihcy ha\'e only 
existed as such since compiiratively recent times. 

The verfuai or balhymrtrUai distribution of animals relates 
to the limits of depth within which each marine species of 
animals is confined. As a rule it is found ihat each species 
has its onn ddiiiite bathymetrical zone, and thai iw cxislencc 
"iffic«lt or impossible at depths jtieater or lew than those 
ipriMd by thai lone. (lenemlismg on a large number of 

cts, naturalists have been able to by don-n and name ccitaia 
dcAnitc zones, each of which hns its outi special fauna. 

The four following zones arc those generally accepted : — 

I, The Littoral lonc, or the tract between tide-marks. 
The Ljiminarian zone, from low water to 15 fatlioms. 
The Coralline lone, from ij to 50 fathoms. 
The deep-sea Coral xone, 50 to too fathoms or more. 
'I'o these must now be certainly added a fifth tone, ex- 
tending from too &ihoms to a depth of 1500 fathoms or more. 

Kccent researches, however, have icndacd it certain that 
after a certain depth, say 100 fathoms, the bathymcirical di^ 
ttibution of animals is conditioned not by the dtpth, but by 
the tanf^ature of the water at the Ijotlimi of the sea. Similar 
forms, namely, ate atwa)ii found inhabiting areas in which the 

Itom-iemiieralure is the sjimc, wholly irreupc^ive of the 
of water in the jMirticiibr locjility in question. The 

pply of food, also, and the nature of the habitat, arc important 
nts of the case. In the light, therefore, of these recent 
dels, it would perhaps be advisable to adopt the views of Mr 
Gwyn Jeffreys, and to consider that there are only two prin- 
cipal bathynivtrical sones—namely, the iitttral and the sti^ 
marint. 

In addtlioD to the prece<ling forms of distribution, the 
zoologist has to investigate the condition and nature of animal 
life during past epochs in the history of the world 

The laws of distribution in time, however, are, from the 
nature of the case. less [jcrfcctly known than arc the laws of 
lateral or vertical disUibution, since these latter concern beings 
which we are aMe to examine directly. The following are the 
chief £acts which it ianeceasai^-forilieatiidcnttobeat inmirLd'. 



42 



MANUAL OF ZOOLOGY. 



I. The rocks which compose the crust of the earth have 
been formed at successive periods, and nuty be rou^y di- 
vided into a<iueotis or sedimentary rocks, and ipieous lodts. 

3. The igneous rocks are produced 1>^ the agency of heat, 
are mostly unslrafi/ied {Le., are not depoeuted in di^inct layers 
or ftra/a), and, with few exccptiODs, are destitute of any traces 
of past life. 

3. The sedimentary or aqueous rocks owe their origin to 
the action of water, arc stratiptd (i.e.. consist of separate layers 
or UnUa), and mostly exhibit "fossils" — that is to say, the 
remains or traces of animals or plants which were in existence 
at the time when the rocks were de|>osited. 

4. The series of aqueous rocks is capable of being divided 
into a numbex of dcAnite groups of strata, which arc technically 
called "foim.itions." 

5. Each of these definite rock-groups, or "formations," is 
characterised by the occurrence of an assemblage of fossil re- 
mains more or less peculiar and confined to itself. 

6. The majority of these fossil forms are " extinct " — that is 
to say, they do not admit of being referred to any species at 
present existing. 

7. No fossil, however, is known, <n^ich cannot be referred 
to one or other of the primaiy subdivisions of the Animal 
Kingdom, which arc represented at the present day. 

8. When 3 species has once died out, it never reappears. 

9. The okler the formation, the greater i* the divei^ence 
between itK fossils anil the aiiimals and plants now existing on 
the globe. 

10. All the known formations are divided into three great 
groups, termed respectively Palawzoic or Primary, Mesozoic 
or Secondary, and Kaino^oic or Tertiary. 

The PalieoJioic or Ancient-life period is the oldest, and is 
characterised by the marked divergence of the life of tlie period 
from all existing forms^ 

In the Meso/oic or Middle-life period, the general /ada of 
the fossils approaches more nearly to that of our existing fatina 
and flora; but — with vcrj' few exceptions — the characteristic 
fossils are all specifically distinct from all existing forms. 

In the Kainozoic or New-life period, the apptoximation of 
tlie fossil remains to exisring living beings is still closer, and 
some of the forms are now sj^iecifically i(lenti<uil with recent 
■pedes ; the number of these increasing rapidly as we uscciid 
from the lowest Kainoxoic deposit to the Kcccnt period. 

Subjoined is a tabic giving the more imporunt subdivisions 



DISTKIBUTION. 



43 



the three great geological periods, coraniencing with the 
>Ulett rocks and as>ccDding to th« present day. 

I. Paleozoic or Primary Rocks. 

I. Laurentiun. (I.o«-er and Upper.) 
a. Cambrian. {Lower nnd Upper, with Huronian Rocks?) 

3. Siluri.in. (ix>wcrand Upper.) 

4. Ucvontan, or Old Red Sandstone, (Lower, Middle, and 
Tpper.) 

$. Carboniferous. (Mountain-limestone, MillKtoneGHt, and 
^ Coal -measures, j 

& Permian. ( = the lower portion of the New Red Sand- 
tone.) 

IL Mesokoic or Skcunparv Rocks. 

7. Triassic Rocks. (Bunter Sandstein, or Lower Trias; 
luMihelkalk, or Middle Trias; Kewpcr, or Upper Trias.) 

8. Juraxtic Rocks. (Lias Inferior Oolite, Great Oolite, 
>idbrd Clay, Coral Rag, Kimmcndgc Clay, Portland Stone, 

'Pwbcck beds.) 

9. Cretaceous Rocks. O^ealden, I^wer Greensand, Cault, 
Jpper Greensand, White Chalk, Maestricht beds.) 

IIL Kainozoic or Tertiary Rocks. 

10. Eocene. (Lower, Middle, and Upper.) 

II. Miocene. (I^wer and Upper.) 

12. Pliocene. (Older Pliocene and Newer Pliocene.) 

13. Poat-tertiiry. (Po$t -pliocene and RcccnL) 



44 



INVERTEBRATE ANIMALS. 

PROTOZOA. 



CHAPTER I. 

I General CHARACTEfts of the Protozoa. 
t2. Classification. 3. Greg ari kids. 

1. General Characters. — The sub-kingdom Protozoa, as the 
name implies, includes the most lowly oi^anised membeis of 
the animal kingdom. From this circumstance it is difficult, if 
not impossible, to give an exhaustive definition, and the fol- 
lowing is, perhaps, as exact as the present state of our know- 
ledge will allow : — 

The Protetoa may be defined as animals, generally 0/ minute 
site, composed 0/ a nearly structureless jelly4ih substance {termed 
" sarcode"), showing no composition out 0/ definite parts or seg- 
ments, having no definite body-cavity, presenting no traces of a 
nervous system, and having either no differentiated alimentary 
apparatus, or but a very rudimentary one. 

The Protozoa are almost exclusively aquatic in their habits, 
and are mostly very minute, though they sometimes form 
colonies of considerable size. They are composed of a more 
or less contractile, jelly-like substance, called "sarcode" or 
" animal protoplasm," which is semi-fluid in consistence, and 
is composed of an albuminous base with oil-globules scattered 
through it. Granules are generally developed in the sarcode, 
and in many cases there is a definite internal solid particle, 
termed the " nucleus." 

In no Protozoon are any traces known of anything like the 
aervous and vascular arrangements which are found in animals 



PROTOZOA. 



45 



• 



a higher grade. A nervous syslctn U universally and en- 
tirely absent, and the sole circidatory 3p[>araius conxUu in 
certtun de^ spaces called "contractile veiicles," which arc 
found io Kome species, and which (louhtfully pciTomi the 
functions of a hcirt. A distincl ,-itimcntary iipcrnirc is present 
in the higher l*r&ti>u>a, but in many ihcrc is none; and in all, 
the digestive apparatus is of the simplest character. Organs 
of generation, or at any rate dilTercntiatcd portions of the 
bod^ which act as llicse, are sometimes pneaent; but in many 
cues tnie sexual rejiroduccion has not hitherto l>een shown 
to exUt 

The " sarcode," which form* such a dislinctive feature in all 
the PfvtMMi, is a structureless albuminous substance, not pos- 
sessing "permanent tlistinction or separation of parts,'' but 
nevcrthcle^ displajing all " the essential properties and char- 
actent of vitality." being capable of assimiktion and excretion, 
of irriutbility, and of ilie power of contraction, so as to produce 
movements, strictly analogous, in many cases, to the muscular 
jvovcmenls of the higher animaU. In some, too, the sarcode 
ics the power of producing an external case or envelope, 
ttsually of catlionate of lime or Ihni, and often of a ver>- com- 
plicated an<l mathematically regular structure. 

'I'he )>ower of airtive lucomotion is enjoyed by a great many 

;of the /V»fi«<M,- but in some cases this is very limited, and 

other cases the animal is permanently fixed in its adult 

'condition. 'I'hc apiiarntus of locomotion in ihc Prt/tosoa is of 

'S rery varied nature. In many cases, especially in the higher 

forms, movements arc effected by means of Ihc liiilc hair-like 

processes which are known as "cilia," and which have the 

power of lashing to and fro or vibrating with great rapidity. 

In other caws the cilia are accom{)anied or repUccd by one or 

nore long whip-like brislles, which act in the same fashion, 

and are known as " flogella." The most characlerislic organs 

of locomotion amongst the lower Pr^auia are known as 

" pseudopodia," and consist simply of prolongations of the 

arcodic substance of the body, which can usually be emitted 

&om the greater portion of the general surface of the body, 

and are catublc of being apiin retracted, and of fusing com- 

']>tctely with (he body-substance- 

?, Claitifiialwn »f the Pretfftoa. The sub-kingdom /Va/Miw 
it divided into three classes — vit, the Crfgarimdet, the Rhize- 
Jrda, and the In/usorui. In the Infusoria only is a mouth 
pfeiwnt, and hence these arc sometimes spoken of as the 
'^S^maladt" Proiasoa, whilst the two former classes collec- 
tively constitute the " yitA>ma/a" 



46 MANUAL OF ZOOLOGY. 

The following is a tabular view of the divisions of the 
Protoioa : — 

Class I. Gregarinida 

Class II. Rhizopoda. 

Order i, Monera. 
„ 2. Amasbea. 
„ 3- Foraminifera. 
„ 4- Hadiolaria. 
„ 5. Sptmgida. 

Class III. Infusoria. 

Order I. Stuioria. 
„ 3. Ci/iaia. 
„ 3. FlageUa/a. 

3. Class I. Grscarikid^. — ^The Gregarinida may be defined 
as parasitic Prolotoa, which are destUute of a mouthy and ih not 
possess the power of emitting " pseudopodta." They constitute 
the lowest class of the Protosoa, and comprise certain micro- 
scopic a.niinals which are parasitic in the alimentary canal of 
both Invertebrate and Vertebrate animals. They have, how- 
ever, a special liking for the intestines of certain insects, being 
commonly found abundantly in the cocltroach. As we shall 
see hereafter, in all probabiUty a great deaJ of the degraded 
character of the Gr^rinida is due to the fact that they are 
internal parasites, and are therefore not dependent upon their 
own exertions for food. 

Nothing anatomically could be more simple than the struc- 
ture of a Gr^arina, since it is almost exactly that of the nn- 
impregnated ovuro (fig. i, n). An adult Gregarina, in fact, 
may be said to be a single cell, consisdug of an ill-defined 
membranous envelope filled with a more or less granular sai^ 
code with fatty particles, which contains in its interior a vesic- 
ular nucleus, this in turn enclosing a solid particle, or nucle- 
olus. In some the body exhibits an approach to a more 
complex structure by the presence of internal septa ; but it is 
doubtful whether this appearance may not be due to the appo- 
sition and fusion of two separate individuals. A separate order, 
however, has been founded upon individuals of this kind, under 
the name ol Dicystidea ; the name Monocystidea being retained 
for the ordinary forms. As regards the size of the Gregarina, 
they vary from about the size of the head of a small pin up 
to as much as half an inch in length, when they assume the 
aspect of small worms. The integument or cuticle with whicli 



protozoa: GREGARIKIDJ& 



47 



the protoplasmic body is enclosed msy be quite smooth or 
striaicd, or it may be furoished wiih biisilcs or spines, or cvtn 
in some cases with cJltsL Sometimes one end of the body is 
rumiithed with uncinate processe*, very similar in appearance 
to the hooked "head" of the common lape-wonn {Tama 
/o/jWBi). Ksscntially, however, the tiructure of all npjj<::irK lo 
be the same. No different iaied organs of any kind be)-ond 
the nucleus and nucleolus exisi, and both assimilation and ex- 
cretion must be performed simply by the general surface of the 
body. The body a, nevertheless, contractile, and slow move- 
menu can l>e effecietl, not, however, by p»eudo|>odia. 

In spite of their exceedingly simply stnicturc, the following 
very interesting reproductive phenomena have been observed, 



KnS^ 










r;roffmm^«iS 




t Wli^ ib« {«nteati divided inip fanKji>iiBfic< 

t Trrt mwc tiifafm «oalcD(* oi Ui4 piaudanaii«llx> (AlWi 



>*/il*Tiu , t The %Miuc enc^lfld \ 
ciltf ; it Froc n*eudoiuvic4ajB ; 
r. (AlWi LiaUriUhn-l 



letimcs in a single Gregarina without apparent cause, 

tomctimes as the result of the apposition and coalescence of 

two individuals — the cxart nature of the process being in 

either ewe obscure. The (jrt^itnna—ot it may be two in- 

ividuala which have come into contact and adhered together 

mes a globular form, bccomc-s motionless, and develops 

itself a siniciuretess envelope or cyst, when it is said 

be " encysted" (fig. i, b). The central nucleus then dis- 

. apparently by dissolution, whereupon the granular 

>tenu 01 the cyst br«il: up into a number of little rounded 

which gradually elongate and become laiiccoUlc, wlien 

arc term«l " pseudonavicella; " (or " pseudonavinila; ") 

I, e). Tht next step in the process constsis in the libera* 

iQ of the pseudonavicelUe. which escape by the rupture of 

>e enclosing cyst (fig. i, ^. If they now find a congenial 

' ital, they give origin to little albuminous or sarcodic 

which exhibit lively movements, and arc endowed 

ith the power o( throwing out and retracting little proces!i«% 

* the body which thscly reseiuWe the " pseudopo*ki" qI v\\e 



48 



MANUAL OF ZOOLOGY. 



Rkiupo^i M that the pMiidonavicella In this condition \i 
very similar to an aclull Amaha (lig. i, t). Finally, these 
amccbiform bodies arc cicvclopwl into adult Grt^rinet. It 
will be seen from the above that the foimaiion of the pscudo- 
naviccll» out of the granular contents of the body, subsequent 
lo the disappeannce of the nucleus, presents sonic analofiy to 
lite s^(ineniation of the impregnated ovum which follows u|»on 
the diuolution of the germinal vesicle. 

PsoROsrsHMt^ — There occur ta jiarasiles on and within 
the bodies of fishes certain vehicular, usually caudjtc, bodies, 
termed Psfiroifxrmia, the exact nature of which is very pro- 
blematical. According to l.iebcrkiihn they occasionally give 
origin to am«ehiform bodies, similar lo those which are Itbe- 
lated frotn the piicudonavicellie of Gr/gariniJa. In this case 
they should probably be rc^;arded as tlie crabr^'onic forms of 
some (frix(tri»i7. By Balbiani, however, ihej- are looked upon 
33 properly belonging to the vcgcUbtc kingdom. 



CHAPTER II. 
RHIZOPODA. 

GeKBRAL CMARjttnriCS OF THE RhIZOPODA, — The ^A(ft»/Wil 

may be defined as Protoifa wkkh art destitute i/a nuntlA, are 
timfiU «T eoiHfxrun/i, and fosttss thi potctr <>/ emitting *' pseude- 

fiedia." They are mostly sioall, l)ui some of tlie composite 
forms, such as the sponges, may attain a very considerable 
size. Stnicturally, a typical Rhizopod — as an Amxl>a — is 
composed of almost stnicnircless sarcode, without any organs 
appropriated to the function of digestion, and posiessing the 
power of throwing out ivoccsscs of its substance so as to oon- 
■titute adventitious limlM;. These are tenned " p%eurlopodia," 
Of false feet, and .ire usually protnisible at will from diflferent 
parts of the body, into the substance of which Ihey again 
melt when they are retracted. They arc merely filaments of 
sarcode, sometimes very delicate and of considerable length, 
at other uines more like finger-shaped processes ; and £ey 
arc somewhat analogous to the little processes which are oc- 
casionally thrown out by the white corpuscles of the blood and 
by pus-cells. Indeed it has been remarked by Huxley that 
an Amaria b stnictwratly "a mere colourlew blood-corpuscle, 

/eaefiagaa uiJcpcodcnt life." 



protozoa: rhizopoda. 



49 



The class JUis&feda is divided into five orders — viz., the 
f-mera, the Atnahta, the Jvramini/tra, the Kadu'iaria, and 
he Spingida^ at which the \sm is uocasionaUy considered as 
I separate clus. 

Ordxr 1. MoNKKA. — Thin ijiime has been proposed by 
lawckcl for certain singxilar organisms which may provision* 
be regarded as the lowest group of the lihisopeda. They 
very minute in si;:c, and arc dibtingxnshwi by ihc fact that 
body is composed of structureless sarcodc, cnpablcof emit- 
thread-like |>roloagations or giuudopodia, but destitute of 
er nucleus or contractile vckicle. The pseudupodia arc in 
he form aS delicate liUmcntous procetaes of larcodc, which 
itcrlacc and anastomose with one another in every direction, 
lul which exhibit a circulation of minute motecuivs and gran- 
in their interior, and along their edges. The body, when 
'u rest, is more or less nearly circuUr in form, but it is capable 
of undergoin)c manifold changes of Agurc. No hard covering 
or " [est " is ever <levelope<l. Reproduction is mostly by fis- 
•ion, with or without precedent encystation and quiescence. 
So far es is knon-n, all the Monrra arc marine, and their syste- 
matic position is .itill doubtful. From the absence of a nudeii9 
and contmctile vesicle, and from tlie nature of tlie pseudopodia, 
they would appear \\^on the wliok- to be most cUiely allied to 
the l-'ifaminiffra, from which ihcy differ, chiefly if not entirely, 
in the absence of a &heil defending the soft sarcodc of the 
body. 





Fl|, ■.— Maifkotacr "f Kliimivdi. m Ammtm nMttit, *ho*lni th« pnudModl*, 
c*imt<il» ■■ J tli, «iid wkIbh: > 0tfhi(<^ villi du fwudopiHlla piwinHled fna 
ih* •BUfta* end a< ih* cw*H«: c iMitUu*! ■pmcc-puildeh Ar ''innnidi:" d 
€Bh *td ipDaBf 'pafliclct vt Gr^^fts, vhgirjiif ihf n^vmblAnca id fla^llAig I nfuuri' 
■w: ' WoMKllbMdiHioidor J/«vMJd. (AriEr Cuilci.) 

Okdkk II. A«<EBKA.— Thisordercomprises those Rhisapeda 
tcht<h arf, with one or two exttpiimi. naked, /lai'f uiually short, 
Ifiunl, Ivhfist fuuiUpsdia, whith do net anoilftKost wUh one 
analiur, and emisin a "nuiieus" and out er mort " mntnu- 
Itte vesica." 

The Anuria, or Proteus-animalcule, may be taken as the 
type, and a description of it will be sufficient to indicate the 

a 








MANUAL OF ZOOLOGY. 

leading; points or interest in the order. Tlie Am«tvi (fig. i, a)\ 
is a iRtCTOtCOpic animalcule w)iich inhaliits (ret)i water, and i*J 
composcKl of gelatinous saroxie, w)iic-h admits of a Kc|iantion 
into tno distinct layert : an outer transpnrcnt layer, termed 
ihc " cctouTC ; " and an inner, more fluid and mobile, molecular S 
Uycr, called the "cndosarc." The "cclosarc" is highly CX'V 
tensile and contractile, and is the layer of which the pseudo- 
podia are mainly composed ; whiUt the " endosjirc " contains 
t))e only organs possessed l>y the animal — vit., the " nucleus ' 
and " contractile vesicle " or vesicles, olonj; with ccnaia for-j 
tttiious cavities termed " food-vacuoies." 

It is believed by some that the ectosarc is surrounded 
a colourless and structureless investing tncmbranc at cuticle j 
but this is denied by others. Be this as it may, tlicre is 
oral cavity, so far as has ever been certainly observed, and 
food is merely taken into tlie interior of the iMdy by a process 
of iiilussuiception- any jiortion of the surface being chosen for 
UiLi pur|^K>se, and acling as an extern ]ionincoiis mouib. When 
the jurticlc of food has been received into the body, the aper- 
ture by which it was admitted again closes up, and the dia- 
duige of solid excreta is effected in ao exactly similar manner. _ 
In this case, hoirever, the area of the genenit surface wiihix ' 
which an anus may be extemporised, appears (o be mc 
restricted, and to comprise a portion only of the 
("villous region"). 

The " nucleus " is a solid granular body, one or more 
which is present within the cndosarc of every AmeeOa, but| 
its function is not known with any certainty. The 
tractile vesicles" are caviiiex within the endoiarc, of which 
ordinarily one only is present in the same individual, though 
sometimes iherc are more. In structure it is a little cAvity or 
vesicle filled with a colourless fluid a[>parently derived Irom 
die digestion, and exhibiting rhythmical movements of coo- 
traction {tysMt) and dilaiaiion (Juuto/f). In some cases radi- 
ating tubes are said to have been seen procevdiog from the 
vesicle at the moment of contraction. Regarded functionally, 
the contractile vesicle must be looked upon as a circulatoiyfl 
organ, and it offers therefore (he mo»t rudimentary form of aS 
vascular system with which we are as yet aciiuainiecL 

Besides these proper organs, the endoaarc usually contains 
c!e:ir :[]>aces, which arc rjilled "vacuoles," or, more properly, 
" food-v.icuoles." These spaces arc of a merely temporary 
character, and arc simply produced by the presence of pai^ 
tides of food, usually with a little water taken into die body i 
itong with the food. 




J 



I'ROTOEOA: KHIZOPODA. 



SI 



There are no Inces of any organs of teHBc, or of a nervous 

3 stem, or, indeed, of any olhvr organs in addiiion to those 
rewly ilcMribcd. Locomotion is effected, with moderate 
activity, but in an trrcgutar manner, by meaOB of ihc blunt, 
fingcr-shapcO processes of sarcodc, or pseudopodia, which 
can be prolnidcd at will from any pan of the body, and can 
be again retracted within ii. The pseudopodin also serve as 
prehensile organs ; Inil they do not interlace and form a net- 
work, nor do they exhibit any ciiculation of granules derived 
from the endosorc, ax in many uthera of the Hhitofioda. 

As regards the reproductive process in the Amakt, no dif- 
ferenliaicd sexual organs have hitherto been discovered, and 
the true sexual form of the process is therefore unknown. 
Fresh individuals, however, may be produced in three ways : — 
Firsl/y, by sunple fission, the animal <lividing into two parts, 
each of which becomes an iiutqieixlcnl organism. Smrndfy, 
by the detachment of a single p^cu(lo]iodiuni, which become* 
de\-el«l>ed into a fresh Amiria. Thirdly, by the production of 
little si>herical mas^s of sarcodc which may be dcri\'cd from 
the nucleus by (tssion, or may be produced by a segmentation 
of the endosarc, the animal having pri;viouity become toq>i<l, 
and the nucleus and contractile ve)>iclc having diiui])pearcd. 
These tittle masses, however jwoduccd, develop tlicniselvcs 
when lilxtatcd into ordinary Atimba. This last method of 
rcptoduction is obviously very closely analogous to the pro- 
duction of " pseudonavicclla; " in an encysted Grfj^arina. 
It has been doubted, apparently with considerable reason, 
whether tlkc so-called Amata arc disiinci species of animals, or 
whether they are not ratlier transitory stages in the life-history 
of other organisms. It is quite certain tliat several of the 
fitvtmfia pass throv^h an Amceboid stage, and it is abo certain 
that v^cuUe matter not uncommonly aiHtumcs similar char- 
acter! (f.g; the mycelium of certain fungi). It is therefore 
not impossible that the forms known to the mtcroscopist as 
Ameriv may be ultimately discovered not to be permanent 
and tiislinct species ; but the evidence on this head is still 
defective. 

Tlie remaining members of the Amaibea are constnicted 
more or len closely af^er the type of the Amaba itself. In the 
nearly allied Di0ugia, the sarcode fonning the 1x>dy of the 
aaioia] is investetl with a membranouK envelope or " carajMce," 
tnengthcncd by grains of sand and other adventitious solid 
particles, and having a single aperture at one extremity, 
throuftb which the pseudopodia are jnotrudcd (fig. i, A). The 
animal gcnerall/ crer/w ibovt Ae^id-downwards, so lo spc&V-, 



52 



BIANUAL OF ZOOLOGV. 






that is to say, with the closed end of the carapace elc\'ale 
above ihc surface on which it is tnoWng. Id Aretlla there is a^ 
discoid or basin-shaped carapscc, accreted by the aniinol itself, 
and likewise possessinj; but a single pseudopudi^l aperturci^^ 
placed in this case on the flat surface of the body. iH 

In Pamfketgus there is no carapace, but the pscudopodia 
are neverthelew proinisible from one extremity only of the 
body, the remainder of the surljtce appearing to be of too^ 
rcDiilant a consistence to allow of this. The common jfo-^ 
animalatk {Aetinephryt si>l) is another well-known Rhizopod 




whidi is URijdly placed in this order (fig. 3). It consists of< 
a spherical m^KS of sarcode, about i-i joo of an inch in dia- 
meter, and nsunlly covered with long, radiating, libmentoua 
pseudopodia, which are much less mobile than in the case of 
the Amteb'.t. The division of the substance of the body into 
cciosaii: and cndosaic ia tolerably evident, and the latter 
conuins niiincruii.i j^r.tnules and vacuoles. The pseudopodia 
arc derived from the ectosarc alone, the endasarc not passing 
into ihcm, and they exhibit a circulation of gmmites along their 
edges, tlimigh this U not ne:uly so marked a fealiirc as in the 
case of the ForamiHiffra. A nucleus and contractile vesicle 
are also present. The long lilamcnious pseudopodia of Attim- 
pkrys make a decided approach 10 the J^cramifti/era, and for 
this reason the sun-animalcule is sometimes placed with the 
latter in a single order. 

The Aitalf^i may be divided into two sub-ordeis: t. j4ihus 
bina. including those foims which have the body naked; and 
3. Artflliita, comprisii^; those in which the body is protected 
by a carapace. 



I 




CHAPTER III. 

FORASiiNIFERA, 

»nw III. FoRAMiNiFKRA. — The Faraminifrra may be 
defined 3s Rhisi'poJa in whUh the body is pr^edtJ by a shell or 
" frit" utua/iy a>m/t>tfj of earbonate ef lime; Iktre is tio distimi 
itfaratton «/ tfu sarosde e/ the t^y into tttosare and endesare, 
anJ tkt nuilais and a'titrtuti/e ivsiele an both abstnl. The pstu- 
dtffiadia art lt»i£ and filaai(nt»us, and interlaa with eae another 
to farm a ndavri. 

'ITie F^ramiHi/era are spedaJljr characterised by the posses- 
sion of :t *' test " or cxicrnal »hcll, which is usually composed 
of carbonate of lime, but is ofteit composed of grains of sand 
or oihcT adventiiiouH solid purtii-leH cemenietl together by 
animal matter, or which, a.s in Gr^mia, may be nimply diitin- 
ous. (If Lifherkiihnia is to be regarded as a Jvmmini/er, the 
poMcwton of a lc»t cnnnot be looked upon as essential, aince 
this animalcule is naked. The Moufra, also, differ from the 
present group Dutnly, if not aliogetJier, by their naked and 
unproiccied bodies.) llie te»t ii usually composed of an 
aggregation of diamber^ or " loculi " (fig. 4, t), and its wall.t 
are usually pierced by numerous iM>res or " forsunina " through 
which the pWUdoiKxIia arc protruded ; the place of these 
bein^ in some forms supplied by the lar]ge siic of the terminal, 
or "oral," aperture of Ac shell (fig. 4, b). The presence or 
sbieiice of foramina in the shell-walls is belie\'ed 10 constitute 
a gentlinc structural distinciion, and the Fumminifera may be 
thereby divided into two great groups {Perfomia and Imper- 
firata). 

As rqpuds the toft inris of the /vramint/era, the body is 
coinpoaed of extcnnic and contractile sarcode — usually red- 
diah or yellowish in colour — which not only ^lU the interior of 
the ahdl, but generally invests its outer surface also with a thin 
, from which the pseudopodia are emitted, 'llie test, there 
, in this case, is not a true cuticular secretion, like that of 
he Afo/lusea, but it is truly immersed within the sarcode of the 
liodjf. Tlte MTCode is not differentiated into a distinct cctosarc 
douxc, and ts devoid of a nudeus and contractile 
, and, indeed, of an^ organs or specialised parts of any 
From (his uniformity m its oompoMtion there seems 
■ome reason to conclude that the Foramini/tra — in spite of the 
complcxiiy and mathematical regularity of many of theii ^VtcVVi 



54 



MANUAL OF ZOOLOGV. 



— should M looked upon as the lowest forms of Uie XAia>fifit6i, 
or even of the Protffxea. 

The jRicudopodia in all the Fsraminifrrti (fig. s,, h. are lila 
mentous mid protmsihlc to a great length, and they poncss the 
singular proiieriy of uniting toKclher in various directions so 
as to form a kind of network, like an "animated spider's 
web." (Hence the name Rft'uuioss applied to the order by 
Dr Carpcnlcr.) This property, however, is not peculiar to 
nMHtbcrs of this order, but is seen also tn Actin^fhryf and in 
the TkalassMiiilit, though to a less extent. Funhcr, through- 
out the entire neta-ork formed by the inosculating pscudo- 







fit; 4-<— Morphalo^y ff Faruniuiftn. *t Lmgf^t n^pmv. a mofuMlulaimma FdntBU* 
nibi: t MltMii (■Air .'khulixX •hnwinc Ih* pHudopadU pfmidict fmm itia 
vti Apcrlure of ihe thall : t DiK^itnm (*hef SchullJcX ibo*^ Ihc nauiilijii . 
khcli with Ihc fvruDiu in Lhe tbsil-vill fiwipc «[■( to a*«udopodia : d Sf cuoa vt 

podia there Is a conttant circulation of ^nulcs in different 
directioni. This singular jihcnomenon is in many respects 
anal()go»s to the circulation of granules which is seen in 
tnuiy ve^cctable cells, and it is bclicted by Dr Carpenter that 
" the conditions of the two seU of phenomena are essentially 
the nme." 

The shells of Jvrami»i/mi may be elated in three divisions, 
termed respectively the " poru-ellanous," the "hyaline" or 
"vitreous," and tlie " arenaceoux." The porccllanoiis shell ix 
quite homogeneous in iu composition, is opaquc-whilc when 
seen by reflected light, and is not perforated by pseudopodial 




PROTOZOA: FORAMINFFERA. 



fomntna. In tha« forms (^jf,, MilMa, fig. 4, d) the pseudo- 
podia tat emitted solely from the tnouth of the lost-ronned 
s^nent of the tJiell. 'Vhn vitreous thcll is transparcDl and 
glass)' in texture, and its walls arc perforated by numerous 
pscitdopodial apcnures. The arenaceous shell is, properly 
speaking, not a true slicll secreted by the animal, since it is 
simply composed of particles of sand united to^'ether by some 
tmknown cemenL It?, walls may or may not be travened by 
pseudopodial foramiiM. 

As regards the form of the shell, the Jvramwi/mi may be 
conveniently, though aibitrarily. divided into two sections : 
the Motttfthalamui and the Pslythaiatnia. In the first of these 
sections (lig. 4, a), comprising the so-called " simple " or " uni- 
locular " Jvramini/fra, the shell consists of a single chamber, 
and the animal is, in fait, nothing more than a little mass of 
sarcode enveloped in a caliiareous covering. Za^ma, with its 
beautiful Aiuk-shuped ^heti, may lie taken iu tlic type of this 
division. Another well-known unilocuUi form is kntosoifnia, 
which is like Lagma in shape, but \\3,f. the tubular neck rcvvncd, 
so OS to be inserted into the interior of the test, In the 
i^^^haiamia, or "multilocular" Foramim/tnx, the shell is 
cmnpOMd of many chanibers separated from one another by 
diviuonal walls or "sei>ta" (fig. ^.t,d,e), each of whidi is [ler- 
fonued by one or more ojKntngs, "septal niicilures," by means 
of which the sarcodc occupying the ditTcrcnt chambers is 
united into a continuous and organic whole, the connecting 
bands being called "stolons." Complex as their struciurc 
often is, the compound foramhti/era are, nevertheless, formed 
by a process of continuous {-cmmation or budding from a 
stagle " primofdial segment " in every respect identical with 
tile pennaDent condition of a simfi/e sjieciex. They <:ommence 
ihcjr exigence, therefore, as MomlA/j/amia, and .me converted 
tnlo J^ythalamta merely by a process of " vegetative " Or " irre- 
lative repetition." As their development proceeds, the primitive 
IBUS of sarcode, or " primordial segment," throw s out fresh 
•Cgneats in the form of buds according to a determinate law ; 
and it is upon the direction in which these segmaits arc 
evolved iluit the ultimate form of the shell de])ends. 1'he 
mora important variations In this respect are as follows : — If 
the additional segments are added to the primordial chamber 
in a lineu scries, so as to form a straight or slightly curved 
line, wc obtain respectively a Nedomria (fig. 4, d, t) or a /Jm- 
talma. When the new chambers arc added in a spiral direction, 
each beinic a little larger than the one vthich preceded It, and 
the coib of the spiral lying in one plane, then we get the " nauli- 



56 



MANUAL OK ZOOLOGV. 



loid " shell, so common amon^t the Jw-aminifira (ftf. 4, e). 
This type of shell is so clgsely simitar to the xhu^ of the Pearly] 
Nautilus, that ihc older naiunilists wlic long in the habit of 
dating ihcic forms along with ihc C(fhahpcda, or Cutlle- 
fuh order. In the mie nautiloid shell the convoltiiions of the 
spiral lie in a single plane, as in RotaliNa, and the shell is said 
to be " equilateral." In other eases, however, the spiral passes 
obliquely round a central axin, an<l the shell becomes conical 
or turrcted, when it is said to be "' inec|ui!aieral " or " trochoid." 
In other forms, such as JVummuIitet (fig. 5) and OrbitoJUa, tlic , 
stnicturc of the shell, though rc{[ular, is much more compli- 
cated. Besides these symroeincal forms, there exist others in 
which the arrangement of the Bcgnienis is very ixrcgular, as is ; 
seen in (ilobigerinii, Actmulina, &c. (fig. 4, /). 

Besides the true pscudopodiat foramina with which the walls \ 
of the teit in niotit of the P^'ramini/a-a are pierced, tliere exisU 
in some fonns an adiliciona! system of complii:atcd branching 
Slid anastomosing tubes, whicji are distributed between the 
laminic of the shell, and establish a communication between its 
extcmat and internal surfaces. 

Classification of FosAMmrPERA. — ^The classihcation of! 
the JvramiMi/era has hitherto proved u matter of extreme diiG- 
culiy, and probably none of the ammjceroenu as yet proposed 
can be considered as more than provisional. The folIoi>ing :» 
the classifi<:ation adopted by I)r Carjx-'nter, who is one of the 
greatest living authorities upon the group : — 

Ordkr Retlci'i.osa. ( = FoRAMisireRA.) — HhUi^odt then'- 
ing no differtniialkti, or a very imperfat one, into tHotart and 
tMosart; n& mikUhs er (Onlra<ii!e vaitie ; psaidopedia fikimatl- 
om, mmuldj ttAdifiided, and inosculating frufy to Jorm a tut- 
iwrk. 

Sation 1. /m/frffrata.^ F.nvelope membranous or calca- 
reoiu, the walls not perforated by apertures for the pseudo- 
podia, which are emitted solely from the single or multiple 
aperture of the shell. 

Familia. I. Cromida. Test membranous. 

2. Mitielida. I'cst porccllanous. 

3. Litmiida. Test arciuccoui. 

Sedim j. Ptrforala. — Envelope calcareous (hyaline or vit- 
reous) or rsreiy Arenaceous, its walls traversed by aumerous 
fonmiina for the emiuion of (neudopodia. 

The following clas.iifi cat ions by iVOrbigny and Schultu are 
/ocxnded merely upon the fonn of the shell, and, as such, are 




PROTOZOA: FORAMIXlFEkA. 



57 



I 



purdy afbitraty. OT tSte two, Schultze's arrangement U pro> 
: bably lh« more satisCu:tory, 

Table op D'Okbigkv'* AmiAXCKUEirT or the FoKAM^tmiiA. 

Ordir I. ii—tttga. — Bodjr coniiktlng of > kincto tegmcnt \ ttie thcll of 
Ik ifaicta chunbcr. 

I 0>wir I. StkktliM. — SnEnwnti amngcd la a vingie row, in s stroighl 
I or tliehlly ouvtd lin«. 

Onltr y Httteatt^. — Segmenli nrrtnecd in > ipimi, ihe shell rorminj; > 
I namba of conroliKioni. (ne " ututilold " FtramuHijftra.) 
I 0n^4. AniMwunQpL — Sci;menu «rengecl on two ittcmailng iukd, 
\ loniiJiiK 1 tptnt. 

Orafr J. fiitt/Uib^. — SegmcnU nmngcd <m two or thrta allemating 
I Bxet, not fonniai; a ipiraL 

Ordrr 6. /IttUiiil^it. — Chufnbcri woiind round on asis, each segment 
cntbcuicg hilf ihc entire ciccumfeience. 

Tanu: or ScKtii.T2R*x Akratcoemxnt or tiix FOKAKiNiraitA. 

SaiiMt t. //fltuvirfoi.— Sesmtnts arranged in a convuliilc wrict* 
Stf/ifn 3. A'kaUtUta. — ScgnKnli ptac^ in a direct line. 
Stttitn 3. &>rtUt», — Seitincnit dbposod in an irrcgukt nuinDei. 

APFlNrrtES or KoRAMtNiKKltA. — The Foraminifera arc re- 
lated oa the one hand to the Amahta, and on tlic otlier to the 
S^oi*f^a. From tlie formeT the " unilocular " Jvramini/era 
difler, both in tlie no^Mcnion of an external envelope, and in 
the much lew hishly diffcrcntiatetl charactera of their sarcod« ; 
but the fioinis ofresemlibncc are obvioux, and in such fonns 
IS AttinafrJiryi and Lirbtrkuhma we are presented with an ap- 
parent transition between (he two orders. From the shelled 
Amnebta, HUch as Aredh, the /vraiHini/era arc broadly separ- 
ated \n the absence in tfie former of p.ieudopudi^l pores, and 
are fumbmeiiL-iHy dixiiiiguished by tlie different nature of the 
sarcode-boily. 

To the Sponges the Foraminifera are related in various 
ways, one of the most striking links being found in Carpmttria, 
a singular anached form of Foramimffr. The shell, namely, 
of Carpmteria b conical and calcareous, composed of an aggre- 
gation of chambers arranged in a spiral, and having its walls 
perforated bv numerous foramina of minute sixe. llie interior 
of the chambers, however, is lille<l with " a fleshy, sponge-like 
body," strengthened by numerous spii:ula. Another curious 
link between the Foraminiftra and the Sponges is llie Squa- 
wuitma lafuh of Ctrter, which is tnily a Feraniimfer, though 
ociginally referred to tlie latter. It consists of an arenaceous 
tot, forming a [kedestal surmounted by an ohverscly conical 
column, fiolh pedestal and column are more or less perfectly 
chambered, and arc filled tvith sani-tranNpaienlycVWtiis^x&ax- 



58 




MANUAL OF ZOOLOGY. 



code. At the summit of the coltunn is a minute aperture sur- 
rounded by a bmsh of spicules, and ihe whole stnictute is fixed 
l^ the peneitial to some solid object. 

To the PiflyeystiNa, the J^amim/tra are obviotitljr and 
closely allied. 1'hcy agree in the nature of the sarrodc-l>ody, 
in the filamentous, inosculating pscudopodia, and in the phe- 
nomenon of 3. pseudopodial circulation of granules. They 
dilTer solely in tlic nature of the "' test," which is calcareous or 
arenaceous in die Jvramini/era, but b always siliceous id the 
Pi/Iyeyitina. 

Bathvbiur, Coccoliths, and Coccospherfj!. — It may be 
as well to notice here a singular organism which is certainly 
referable to the Rhi^poda, though its exact affinities arc 
doubtful. Certain minute oval or rounded bodies have long 
been known as occurring attached to the surlace of the shells 
of fiframini/era, and they were originally described bj" Pro- 
fessor Htixtcy under the name of <iKtelitki. Subsetiuenily it 
wa-s discovered by IJr V\'al]ich that these singular bodies occur 
nol only in the free condition, but also attaclied to the external 
surface of little spherical masses of sarcode to which he ^ve 
the name of (Kc^tpkirts. The teetotfifura arc enclosed tn a 
delicate envelope apiiarcnUy of a calcareous nature, and are 
studded at nearly regular intervals by the toetolilhs. More 
recently still, il h.ih been ili.tcovered by Professor Huxley that 
both the <0{(o!itht and the eottospAer/s are embedded in masses 
of protoplasmic or sarcodic substance, covering wide areas of 
the sea-bottom, to which they bear the same relation that the 
spicules of sponges or of Jtadiolaria do to the soft parts of 
these animals. To this undefmed and diffused protoplasm 
with its contained MealilAs and eeicospkera the name BalkyHiu 
hiu been applietl by Professor Huxley. Its exact ]>osiiion, as 
already snid, is doubtful ; but it is believed by Dr Ciir[>enler to 
be a rudimentary form of the Ft/ramiii/fra, and to be somewhat 
allied to the ancient Mmwu. A curious point as regards the 
axro/i/At has recently been brought to light by Dr Uiirabcl, the 
celebrated paleontologist, who believes that he has succeeded 
in demonstrating in thcni the existence oiaUuleit, or of some 
substance closely allied to cellulose. He hax also sliown that 
bodies similar to, if not identiol with, aee^ilks, occur in for- 
mations as old as the Potsdam Sandstone (l>ower Silurian) of 
North America. More recently still, Mr Carter has shown that 
etaoJitks occur in great numbers in the Laminarian zone, and 
he asserts them to be sotiiary, unicellular, iialcarcous Algae. 
He describes them tmder the name of Mtichetia uniaUidarij 
and Af. JiUMS, according as they are oval or round \ and he 



PKOTOZOA : FORAMINirKKA. 



59 



believes that the tottoiphertt are most probably tlieir "spor- 
u)^" Upon (his view the lerm " coccolithx ^ n-ould be ic- 
stncted to the focsil foma. 

DiSTRiiiVTiON or FoRAMiKireitA IN- Space. — TVz Fcrammi- 
ftra arc mostly marine, and arc found in almost all seas, iliough 
more abundantly in (hose of ihc warmer pans of (lie kI<>1>c 
It is concluded by Dr Carpenter tliat "tlie foraiiiinitcrous 
fauna of our ovm leas probably presents a grearer range of 
vanety than existed at any prereding period ; but there is no 
indication of any icndeixy to elevation tottanls a higher type." 
One of the most remarkable facts about their distribution at 
the pmcnt day, is the existence of a deposit at great dcptlii 
in the Atlantic, but only in areas traversed by heated currents, 
formed almost entirely of the shells of Fornmini/era, and very 
closely resembling chalk. It ha* further been tpiite recently 
established that there coexist with tliese Fdraininija-a various 
animals of a higher grade, some of which closely resemble, or 
are even s))ecifically insmarable from, well-known Cretaceous 
species. 'I'here is therefore some reason to conclude that the 
bottom of the sea at great depths is peopled at the present day 
by s fauna which is very closely allied to that of the Chalk. 
Most living Jvriimim/fra are very minute, l»il some of the 
extiiK;! forms attained a sixe of as much as three inches in 
circumference {e.g., the A'ummu/iU, fig. 5), and spheres gf 
ParJtfria may attain a cimimfercncc of nearly four inches, 
Some forms may be obtained adhering to the roots of tangle 
at or near low-water mark, but they are mostly 10 be dredged 
from tolerably deep water, 'lliey have been found, in fact, in 
great abundance in the deepest pons of the ocean which have 
as yet been examined by the dredge — at a de|>th, namely, of 
ttwiy three miles. 

DisntinvTiON op Foraminipeka ts Timb. — Remains of 
Faramini^fra have been found in Fala:oxoic, Mesozoic, and 
K.-tinoroic fonnations. In the oldest stratified rocks with 
which we are acquainted — viz., the Laurcnlian rocks of C3na<la 
—there occurs a singular body which has been described as the 
mnuns of a gigantic Faraminifer, under the name of Eoto^n 
Ctmadenu. If truly organic, as is doubted by some, it is the 
oldeM louil as yet diicovernL It appean to have grown in 
reef'like nassct resembling the senile i>atclies of IW^lrema* 

* /^ff1rrm» U > little bnnchrd coral-like Fomminifcr. compottd of a 
olnreow leil funning a nunibct of irr«guUr chunbcn. which commnnliale 
vilti one mMhcr b^ wide orilicn. and UK Rllod wiih coIouHch Mrcode. 
The walk of the cbkintfcn are alto pcnctnted bj an eileiuiic ijiun of 
opflbry OBiiU. 




MANUAL 



and Oirptntiria, to both of which, as u-ell as lo the extinct 
Nummiiiitfs. i( shows a decided aflinity. In the Sihihan rocks, 
retnaint of Faramini/tra, some of which arc apfinrenlly identi- 
cal wiili exi&iing forms, have been detected in various pLtccs, 
and it is not improbable that the Laigc Silurian fossils known as 
Rtc(ptaeulita and Str&matsfiera should rcall)' be referred to this 
order. In the Carboniferous roclcs of Kussiji whole beds are 
composed of a species of Futulma. In the Secondai)' roclcs 
F^rttmini/aa occur in great abundance, the widely-spread for- 
mation known as the Chalk being crowded with these organ- 
isms. Clialk itself in fact, is aImo« entirety comjioscd of the 
cases of feramim/tra, some of which are identical with species 
DOW existing. 




Fig, y-~Kmmmmliln l^tifmtmt. Gxaic 

In the Tertiary rocks the Jvramini/era attain tlicir maximum 
of development, both as regards the site and the number of 
tlie forms which characterise them. The period of the Middle 
Koccne is especially di.>uingui)ihed by a vcf)- widely spread and 
easily reeognued rock known as the Ntiminulitic LimcstoDc. 
so called from the abundance in it of a large coin-shaped Fi^it- 
minifer termed the Nummulite (fig. 5). The Nummulitic Lime- 
stone stretches from the west of Europe lo the frontiers of 
China ) but in some cases, in place of NumtnutUa proper, it 
contains the remains of a mimetic form tcnned OrhitoUn. 
Upon the whole, Dr Carpenter concludes that "there is no 
evidence of any fundamental modihcation or advance of ihc 
foraminiferous type from the I*alicozoic period to the present 
time." 



protozoa: radiolaria. 



61 



CHAPTER IV. 



XADIOLARIA. 

Order IV. Radiolakia. — The order Radiolaria ms 
winded by Miillcr to inchidc the Potyeyitina, the Acanttwrnti- 
and Ihc Thalaniatllid^. to which Dr Carpenter adds 
hrys and its allies, thieHy on account of the form of the 
JOfKidia. Here, however, the term will be ciuiiloyeil to 
le the first three of these, and A<tinopkrys will be 
pUced amonsu the Amaixa, to which its alliance i[>{>enrs to be 
□ore decideiL Most of the Radiolaria are marine, Inil «omc 
e«r forms of TAalauicollida have been described as occurring 
lit) fresh water. 

The order RadMaria may be defined ns comprising those 

^Aitefods teliieA /msetj a tUi^/tmt test or silieeous sfKuJes, and 

T frffeided with puudopoiUa wkUh stand out likt radiating fila^ 

1//, and eaasiwtaUy run into one anther . 

I. FaMii.V Acanthouetbina.— The A eanfAi'metra (fi^. 6, a) 

all minute, and arc found floating near the surface in the 

ocean, sometimes in great numbers. They consist of 

je-bodics whkh arc supported by a framework of radiat- 

ailiceous spines, the extremities of which usually project 




n^ ^^Ht /trt'^l*'^ff¥a lAmrr*M*; S //Mfi^mjH^ Afjimtitiriium. one gf lbs 
/VX^iJjAd. tk^vinf lb* nduiinf ianiiiapoiiu (ATuc MUllnr-) 

coniiderat>ly beyond the body. Tlie xuhstance of the body 

■dmiu of division into an outer membmnout layer, or *' ecio- 

iBaic," and an internal granubr layer, or " enilosarc" 'J1ic 

liliceous sptncs are hollow, being grooved at the ba^c by a 

atter, which is continued futihcr up the spine by a canal tct- 

ilii»g at the apex ofihc spine by a distinct ai)crtiirc. The 



62 MANUAL OF ZOOLOGY. 

spmes, in consequence of this structure, are able to serve for the 
transmission of the pseudopodia, which gain the exterior by 
running through the canals and escaping at their apices. Many 
of the pseudopodia, however, do not occupy the canals of the 
spines. 

II, Fam. Polycvstina. — The members of this family are 
closely related to the Foraminifera, differing from them chiefly 
in the fact that their shells are composed of flint instead of 
carbonate of lime, as in most of the latter. They possess a 
body of sarcode, which is enclosed in a foraminatnl sUiceous 
shell, which is often furnished with spine-like processes, and is 
usually of great beauty (fig. 6, b). The sarcodic substance of 
the body is olive-brown in colour, with yellow globules, and 
often does not entirely fill the shell. The pseudopodia are 
emitted through the foramina in the test, and are long, ray-like 
filaments, which display a slow movement of granules along 
their borders. 

The Polycystina are all microscopic, and are all inhabitants 
of the sea, having a very wide distribution. They are also 
found abundantly in certain Tertiary deposits, being often er- 
roneously described as DiatomtKue. 

III. Fam. Thalassicollida, — The TXa/ajjiarf/a/a have been 
defined as being Rhitopoda which are" pravuied with struetvrdess 
cysts coniaining cellular elements and sarcode, and surrounded 
by a layer of sarcode, giving ofi pseudopodia, which cotnnumJy 
stand put like rays, but may and do run into one another, and so 
form nOworks." — (Huxley.) 

The TTudaisicollida may be simple or composite, the latter 
consisting essentially of aggregations of the former ; whilst 
these are fundamentally composed of a mass of granular pro- 
toplasm, containing a nucleus, but without a contractile vesicle, 
" enclosed in a membranous capsule, which is in turn protected 
by a more or less thick gelatinous exudation, whilst numerous 
sorcoblasts occur scattered through the endosarc, and occa- 
sionally a few may be seen suspended within the external gela- 
tinous stratum."— -(Wall ich.) The whole organism is supported 
by more or less extensively developed skeletal structures. The 
skeleton may he simple, consisting of a delicate fenestrated 
shell ; or may be compound, consisting of a number of spicular 
masses. 

The three best-known genera of the family are Spheergioiim, 

ColA'sphirra, and I^alassicnlla. They are all marine, being 

found floating passively at the surface of most seas ; and they 

vary in size from an inch in iliameter downwards. SpharoMoiim 

consists essentially of a numbei of spherical sarcode-bodies 




protozoa: SPONGIUA. 

called •■ ccllstfonii bodies") with distinct nMlei, 
surrounded by a zone of siliceous spicules, the vrholc being 
embedded in a common gelatinous nutrix. I1ie ceutre of lUe 
nuus ia vacuola[e<), sometimes to luch an extent lliac it be- 
comes > hollow sphere. 

In Ci^l^phara, llw spherical body — which is very like that 
' the preceding fonn — is enclosed in a transparent siliceous 




I rte. T,— M«tiJM4in <l Radiolatu. a Sn<ciou> renotnled tal of CtHn^imni 
I IfMMify/i; i rktiviir^U mt^rmm, thoKKic c^LlKliifm bodid^ f«cn|iQ(uu] groupB 
it ninfci. mJ ndiilinf fmtuliafoliiA. 



Bvelope, which is pcrforaicd by numerous rounded apertures 
" fenestra." This fonu. ihcteforc, approaches very closely 
the P»/ytyitiiia, especially to those in which the furamina 
: so large that the test is reduced to a mere reticulate Irame- 

»o»lt (fig- 7. ")• 

Thaiassitviia differa little from cither of the above in fiin- 
dunental strurture, but il contains n numher of compound 
lilioeous spkules embedded in its ectosatc (fig. 7, 4), 



CHAPTER V, 



SPONCWA. 

Orrer V. Spo^iotDA. — 1'he (rue nature of s])oiiges has long 
en A matter of di^jnitc, but they are now almost iinivcncilly 
Verted to the animal kingdon, and placed either in or near 
be Rhi»«foda. Some observers slill maintain the vcgctat>k 
iture of sponges, but this opinion has no real grounds for its 
BppoR, and is chiefly founded upon loose analogies, and upon 
> certain similarity in oulwar<l form. 
The SfeifsiJa may \ie dcAned as " tarcoJe-iodia^ deilititte oj 




MANUAL 

a JBMW/A, and UMtt/J intu a compt'sife mast, whicfi u traverttd 
MntiU fiftning en Iht surfact, and it almoii ahiiiyi sufpoiiot 
by a framms>rk of fumy fibrts, «r (•/ sUurotu or taitarena 
*/««/«."—( Allman. ) 

From the above dcliiiilion it will be seen that a sponge 
is composed essentially of two elements — a soft, gelaiinouE, 
invextini; "flesh," and an inienial KUpi}orting fnime«-orit or 
"skclclon." 

'rnking an ordinary homy sjionge as the iy|je o( the order, 
we lind it to be composed of a :(kclcton (Ag. 9, </) of homy 
reticulated fibres which interbce in every direction, and are 
pierced by numerous aperture^ the whole surrounded exter- 
nally and inlemally by a gelatinous gUiry substance^ like white- 
of-^i the so-called " sponge-flesh." The homy skeleton is 
comjMncd of a substance called "keratode," and is usually 
strcngthencrl by spiaila of lime or flint, which also occur less 
abundantly in the «pongc-flcsh. 1'hese must not, however, be 
confounded n-iih the skeleton of the inic calcareous or siliceous 
sponges in which the kcratode is wanting. Of the apertures 
which penetrate the substance of the sponge in every direction, 
some are large craieriform openings, and are termed " osculcs," 
or "exhalant apertures;" whilst others, which occur in much 
greater numbers, are greatly smaller in sire. an<l arc termed 
" pores," or " inhalant ajwrtures." Itoth the o«cuU and pores 
can be closed at the will of the animal ; but the oscuLu are 
permanent apertures, whereas the pores are not constant, biit 
can be fomied afresh whcnocr and wherever required. The 
" sponge- flesh," which invests the cnltte skeleton, is found 
upon a microscopical examination to be entirely com]>osed of 
an a^Tcgation of roun<led amcebiform bodies—tUe so-called 
" sponge-pattirk-s" or " sarcoi<b " (fig. 2, e, d. e\ Some of 
these .ire ciliatcti ; whilst others are ca|»ble of emitting pseu> 
do])odia from ail parts of their surface, and are provided with 
nuclei, thus coming closely to resemble so many Anurha. Re- 
garding the skeleton as something siipcT-iddcd, wc may, in fact, 
took upon a sponge as being essentially nothing more tli^n an 
aggregation of Amaba, since each " sarcoid " is cafiable of 
proairing and assimilating food for itself in a manner strictly 
analogous to what we have seen in ilie Amieha. This view 
becomes still more easily comprehensible when we consider 
the simplest condition in which a sponge occurs in nature (as 
exenipltlied, for instance, in certain of the Ca/eufiottgia); the 
condition, namely, in which the entire sponge consists of a 
colony of amcebiform sarcoids, secreting a common skeleton, 
but pTorided with only a single " osculum," and a greater or 




PROTOZOA: SPONGIDA. 



6S 



less number of inhalant " porM." There nie, in fact, many 
who hold that the more complex s[)ongcs arc merely produced 
by the aggngiiioa together of a number of these simpler 
ooloniei. 

In a living sponge a constant circulation of water is maio- 
taincd by means of an aquiTerous system (fig. 8), which U 




Pk. >— rf il giir mai; waHa <4 SfrngiiU iattet Kutlrr} 4i n SupcrlWIil UyCT or 
J«fil —il«Mn;* > t InlwUiii nimturE* nr ~ pun*:" i t Gliaud dum- 
boi; J An nhilul «f miifii or "okuJiud.' The %mvt indiout Ibi dlrecnon 
arUMcanfBtM. 

cooadtuled by the oscula and pores—^rcady alluded to— and 
by m system of canals excavntod in the siibst.nnce of the 
■poogc and uniting the two SL-ts of apcnurcs. The vaicr 
passes in by the "poics" or inhalant apertures, and is con- 
veyed by a series of canals — the " inaiirent " or " aifereni " 
CUiab — to a second series of tubes— the ■' cxcuirent" or 
"cfiereot" canals — by which ii reaches the "oscula" ajid is 
finally expdled &om the body. These processes are regularly 
wrf^med, and their meclianiiim was long a subject of Kperii- 
iatton. It is now knon-n, however, that beneath the superli- 
cial layer or "derma] membrane" of the sponge there exist 
chambers lined with E[>onge- particles which are provided 
with vibratilc filaments or cilia {fig. 8, c, c). The pores open 
into these chambers, and Trom them proceed the incurrcnt 
canals, each being dilated at ils commencement into a sac, 
which is abo lined with ciliated sponge-particles. By the 
vibralile action of these cilia, currents of water are caused to 
set in by the pores ; and as out-going cunentt jiroceed from 
the oscuta, a constant circulation or fresh water is maintained 
through th« entire sjionge. In this way each individual 
sponge-panide is enabled to obtiin nutriment : the jiroccss 
being al the tome time not improbably a rudimentary form of 
respuaiioo. The chambers or ucs lined with ciliated sarcoids 



66 



MANUAL OF ZOOLOGY. 



have been shown by Mr Cuter to be the essential element tnlj 
the organiaation of the fresh-water and Durinc sponges, and to] 
be the fundamcnial expression of the alimcniaiy sj-sicm. 

The reproduction of sponges niay be effected cithe 
asexunlly or sexually, the following being x brief outline of] 
the phenomena whidi liave been observed in the commooif 
rreHh-waier s[iongc (Sffftigjila), \a which the process hits been ; 
most accurately noticed. 





FSf. a— « Ccramolc sf SftHgHbit A HOurn: i IHiwuHiialH: K<«iaa of ihc fna*^ 
Biiil(. thawing iht iniMf \ayv ol unphidlm aiHl th« itinit ouu o( «!!• : i Oat f 
of Ihc uii|)hvliKA leru In ^rtflle ; J Vntpotat of lb« ihtlctaa 4f ii hamy ipcnii 
(iiffa Bqfr^rbanlO. thJcrtriDf iIh inlerUcuif hdrny Gbra viEh vpiiCvU. All ^" 

Inagnitifd. 

In the first or asexual method of reproduction, which takes 
place in the winter, the deeper ]K>rtions of the sponge are 
found to be filled with small sccd-hkc rounded bodies, termed 
"gemnjules" or "spores," each of which possesses a small 
aperture or "hilum" at one point (fig. 9, A). Each gcmmulc 
is composed of an outer cuHaceoua capsule surrounded by a 
laver of jieciiliar uteroid .spictila, membling two toothed 
wheels united by nn axle, and termed *' amphijiscs " (fig. 9, t, 
f). 1'hesc amphidiscs are embedded in sarcode, whilst tndr 
inner surfaces rest upon the icssclated capsule already men- 
tioned. In the interior of the capsule thus formed is a mass 
of cells, of which the central ones contain numerous germs. 
When tlie spring comes, these masses of "ovi-bearing cells" 
arc discharged tlirough the " hiliiiii " d the gemmule into 
water, and are developed into new Spongii/a. 

S^onplla also appears to reproduce iincif in a somewhat an 
logous manner by means of what are termed " su-nmi-xi>orcs 
These uze small bodies, coutaioing reproductive germs, and 



lis- 

na-iH 

:s/^ 
md 



PROTOZOA : SPOKGIDA. 



az 



provided with numerous dlia tiy which they move about actively, 
becofning linallx attacl(c<l to some solid body, and developing 
thcnucives into the adult sponge. 

In (he second or M:xual method of reproductioo, certain of 
the spongC'paniclcs or "sarcoids" sepBTSIe thcmielves and 
become nucleolo-nuclcatcd, thus coming to resemble ova. At 
the same time othef sarcoids become motionless, and their 
contents become molecular, and are finally converted into sper- 
matoEOB. liy the rupture of ihexe, and by the consequent 
contact of the different ek-n)cnlt, embryos arc produced, 
which arc at fint ciliated and move about freely, becoming 
cveotuaily Btabonary, and developing into dcw individuals. 

CLAssincATiON OF THE Sposoes. — The Sfongida have been 
vuiou^y classed, and a good natural arrangement is still a 
Jaideratum. By Dr Bowetbanic they are somewhat arbi- 
tiwily arranged m three orders — viz., the Ktratesa, the SilUea, 
and the C^arta, of which the lirst is believed to hold the 
lowest place. In the Ktratota the skeleton is composed of 
interlacing homy fibres, usually strengthened by spicuU cither 
of flint or lime. In the dulotrea or Cakiiponpa the skeleton 
is composed of carbonate of lime ; whilst in the Siiuavt 
sponges it is composed either of spicules of silex, or " of solid, 
bminaied, and continuous siliceous fibre." By Professor Wy- 
villc Thomson the siliceous »[)onge» are atranged in a sq)aratc 
order under the name of the " vitreous sponges " ( Vitm). The 
nature of the skeleton thus xarici: considentbly, whilst the spi- 
coks show ahnost tndehniic modifications of shape, though 
they are constant for any given species, in any given pan of 
its organisation. Tlie spoogc-llesh is much more uniform in 
its nature and composition. It may be noticed, however, that 
in SfcngiOa the sponge-particles are lilted with green granuln, 
which arc apparently identical in chemical composition with 
the green colouring matter of plants (<jUi?ri^if>>j7). In Grantia, 
too, the sarcoids arc furnished with long filamentous append- 
^es or cilia {fig. i, </). The siliceous sponges ate mostly in- 
habilaais of the deep sea, and many of them arc remarkable 
for their long and slender spicules of flint. In JfyaJtmema, or 
the gUM40pe, long placed amonnl the Zoophytes (Zmmharia 
idtniatiat), there is a cup-shaneu Nponge-l>Dt1y, tnip^rted by a 
rope of long twisted siliceous nbm, which are sunk in the mud 
of the sea-bottom. In other "anchoring sponges," such as 
PSavnema and Holtt»ia. the body is Ksslle or stcmleu, and is 
moored to the mud by a beaid of long delicate spicules. These 
fpoQges, in their single, long, chimney-like osculum, show % 
curious resemblance lo ihv fossil Sifi^iat of the grccnsand. 



63 



MANUAL OF ZOOLOGY. 



Similar root-fibres of flinl, travcning the mud in every direc- 
tion, ocxrur in the beautiful Vcnui' f lower-basket (Euf{(fltlla\ 
without any exception one of tlic most exquisite of alt organic 
xtnictiirc;! known tu us. 

UisTRiBUTiON o? SpoNGKs IN SPACE.— SpOH^ are almost 
exclusively marine, the Sponsilla alone being inhabitants of 
fresh water ; and they are of almost universal occurrence. ITie 
sponges of commerce arc mostly obtained from the Ureeian 
Archipelago and the Bahama Islands. Recently the existence 
of numerous siliceous sponges at great depths in the ocean has 
been demonstrated by Drs Carpenter and Wyville Thomson. 
They are associated with numerous Faramim/tra and with 
CritMuitat the whole assemblage bearing a singularly close rc- 
serablanoe to Ihc lituna of the Cretaceous epoch. The com- 
mon marine sponKes are mostly found attached to some solid 
object between tide-marks or in deep water. The ritieou* or 
siliceous sponges appear to be exclusively inhabitants of the 
deeper parts of the ocean. One genus (C/iofta) inhabits 
branching cavities in shells, which tlie sponge excavates for 
itself apparently by means of its siliceous spicula. Fossil 
shells nimed by a boring-sponge, allied to the recent Cfiffia, 
are found from the Silurian rocks upwards. M 

DisTKiDUTioN liv SfoNUES IN TiUE.~Rcmains of spongct V 
arc known to ocair in formations belonging to the Palaeozoic, 
Mcsozoic, and Kainozoic epochs, Hie kcratosc or homy 
sponges are obviously incapable of leaving any evidence of 
their existence, otherwise than by the preservation of the 
spicula with which the skeleton is fiimisncd ; and sudi are 
occasionally found, though the)- are of rare oocunence. The 
calcareous sjwngcs arc found from the Silurian rocks ti])ward^j 
attaining their maximum in the seas of the Secondary epoch 
the Chalk being especially characterised by their i^rescnce 
The most important group of fossil sponges is that known asl 
the Petroif^ipadit, characterised by the (wssession of a sionjpj 
reticulate framework or .skeleton, and by the absence 
spicuia. The most important Renera of tht.s group are 
sisf^Hgia (Devonian) and Ventrietililei (Ch.ilk). 

Of the Palxozoic sponges. Anfxt^^hut is found in the 
Poiidam sandstone of North America (Upper Cambrian?);] 
PeUaosponpa and AtoNlkospon^a are familiar Lower Silurian 
forms i and Auif/ihfmgia and /iitw/VHgiit occur along wit' 
other forms in the Ltidlow rocks. In the Devonian rocks'' 
sponges occur pretty frequently, S/atris^fiMgia being the com- 
nvoncsi genus. (The Devonian Sle};aaoduivum is really the 
cephalic buckler of a pttraspUean Ush.) The most important 



A 



PRUTOZOA : SPONGIDA. 69 

S*oic genera of sponges arc VentrieulUts and Siphmia; 
voA the order appears, upon the whole, to aiiaiii ib maximum 
in the Crci3ceous epoch. There seeros no reason to doubt 
but that many of the chulk-tUnts owe ihcir origin to sponges ; 
and in some sections of flint are found mimilc " Kpheri(Hil bcKlies 
covered with radiating and multiaijpid spines," which have 
been termed Sfini/erilet or Xanthidin. and arc probably the 
"getnmgJes" of sponges. (By some, however, these bodies arc 
regarded ax being the "spontiigia'' of Dtsmidia. an order of 
the Pratfif^yta.) Many Cretaceous and Tertiary shells are 
found to be mined by a, species of boring-sponge, which is 
neuly allied to the recent CHona. 

ArriHtnes or Sponges. — As already pointed out, the 

sponges are allied both to the Amabea and to the Fgramiaifera. 

Indeed the individual "sarcoids" orspongc-pRrliclcscan scarcely 

be dbtinguishcd, when detached, from Amx6{t. The sponges 

show libcwiM a decided rcUcionship to the JiaJMaritt; .ind 

by Frolcssor JamACIarV they arc bcHcvcd to be nearly allied 

tothe"flagcllate'' Injtueria. This obsener, in fact, &utes his 

"conviction Ihji the true eilialed SfVngia are not ^.ilsd/irfs in 

any ierne nhatever, nor even iloscly related to them, but are 

genuine comjiound fia^<Uaii Jht^atea." To prove this view. 

however, it should be shown that each sponge-particle posscssn 

at any rale a distinct mouih, with or without a rudimentary 

alimentary canaL Iktorc recently Dr Ernst Hsckcl and others 

have endeavoured to show that the sponges arc most nearly 

allied to the Sea-anemones {Aciiitotoa) ; but this seems to have 

arisen from a nusconceplion as to tlie eom[iound nature of 

the fufmer. Three views, namely, may be hel<l as to the 

" iftdividiulily" of a si)Onge. Firstly, it may be held thai the 

entire organism which we call a sponge is n single animal. 

The microscope has rendered this view wholly untenable. 

Stemdly, it may be held that the entire sponge-mass is a single 

"footogical individual," of which each s.ircoid is a single 

"lobid." As each sponge-mass is certainly in most cases the 

prodtu-t of a single ovum, this is the most probable and reason- 

ible view. Thirdiy, it may be held that each sponge-mass 

coBiisu of a number of nfigr^te<) " individuals," each of which 

bcoostituled by a simile exhnlant "oxculum," together with 

the ^jeatcr or lets number of inhalant " pores " thereto apper- 

taioiog. Upon no other view than this docs there appear to 

be any relation of afhoity between the sponges and the dr/m- 

tatHa ; and even on this view the general affinities betftcen the 

two are not of a very stKlcing nature In some catcs (such as 

EufltAila amongst \:cxSiJuii^t^, xn^Sy^um and (JU among^ 




70 



MANUAL or ZOOLOGY. 



(he Caleitfx^tgut) llw: adult sponge nc«r roiwitts or more ffian 
a single osculum And the pores belonging to it, romti luting wh.-it 
Haxkcl terms a single "person." Most si>ongcs, however, 
Tonn a " stock," consistiiig of »evcral such "pcnons" united i 
together. 



CHAPTER VI. 

INFUSORIA. 

Thk Jttfum-ia of maiijr writers comprise many of the lowest 
fonns of {Jants— such as the Diatoms — together with the Itoti' 
ftra, a class of minute animals now known to belong to the 
Anauloida. By modem wriicre, howc%'cT, the term Injutoria 
U used strictly to designate those J*rotetea which possess a 
mouth and nidimenury digestive cavi^. They are, for this 
reason, ofteu called coUectiVely the " stomatodc" Pret^ea, in 
contradii^tinction to the remaining members of the sub-kingdom, ' 
which arc all "astomatous," The »o-<alled "suctorial" tnfU'\ 
soria {Acineia), however, appear to have no definite oral aper- 
ture; and the same is the case with the parasitic OfiaJina, 
though there is great doubt as to the propriety of placing this in 
the Infmvria at all The name fn/Moria itself is derived from 
the &ct that the members of tlie class are often dercloped in 
organic infusions. ■ 

The In/meria, or Nematode Pr^&sea, may he defined as Pr^- I 
tnea Vthich are m>sify prm-idtJ wUh a mcuth and mJimentarj 
^UgaHvt ttn'ity, vfiifA do twt fotstu the fsmvr if/ emitting fseu- 
mfo^ia. but u-hi^A are fumished with vikratUe eilia, or viith 
tet^ractilt fiiiitenU. They are mcitly mitraseopit in sixe, and 
their dadies usvaliy eensitt of three disfhut iayert. 

The In/ttsoria may be divided into three orders — vit, 
Smtffria, Ciliata, and Plagellata, of which the second comprises 
the majority of (he membera of Uie class, and alone requires 
much ooiuidenilion. 

I. Okokk Ciuiata. — This order comprises those Infusaria 
in which the outer layer of the body it mere or leu abundantly j 
furnished with vikratile eilia, whith senre other for tocotiwtioa ' 
or for Iht froeuring of food, Itesides tilia, properly so called, 
some of the ciliated Infusoria arc [>rovided with styles or jointed 
btisdes, which arc movable, and subserve locomotion ; whilst 
othets liave little hooks or uneini, with which they can attach 
tAemje/ves to foreigD bodice. As types of the order, Paramo!- 



A 




PROTOZOA: INFUSORIA. 

mm and ForiUdla may be selected, (he former being free, 
whilst the laticT h i>ennaQenlly fixed in ils aduli condition. 

fiaramaauMi ikg. to, ^) b a sIi|>|>eT-sbape(l animalcole, com- 
posed extem:ill)- of .1 stnicturete^K trnn!i|iarent pellicle— the 
" cuticle " — which i* lined by a layer of fiiro and consistent sar- 
code, which is termed the "cortical Layer," or tbc "parcnchynia 




k 



rtc. w— Mttpkalasir oT iBTuKirii: <• S/irt/la. ■ UilUd tnfuKriin; t A ^ngli 
ohn M Uu iMM (Huly Ba|>iilli«d. ihinrlnc clit crilaidl dlic wtuch pninidH U 
iHiL.M' <h* lillMM Ui«ni>l c*>4iy Imo *h>di l^e |Mnide> of fosd in r«<it>ciL 
w trt t—c c jf thcbod^iR the (MiLrmcfalc vcncle ibd tmaLIf fo4d'Vicunl*» 
_ -iiMtari" rtf rtirnrannn df ^itniJiMvVhHa^ ihnwifij ihf fivnntl-thanei^ Collet* 

of the body," this in turn passing into ft ccnusl mass of softer 
and more diffluent sarcodc, knon-n as the "chyme-mass," or 
"abdominal cavity." The "cuticle" is covered with vibnttUe 
cilia, and is perforated by the aperture of the mouth. The 
mouth lesds into a funnel-Khaped gullet, which is not rontimicd 
into any dixiinci digestiv-e »ac, but it \o» in the ccnlml "chyme- 
nui.'' Within the "cortical layer "are the "nucleus" and 
"nucleolus," and the "connaclilc vesicle"' (or vesicles). The 
nadens is usually a solid bind or rod-shaped body, having a 
■laati spherical panicle applied to its exterior, or immersed in 
its flidwtance. Tliis latter is the so-called " nucleolus," which 
must be carefully ilrttingtiished from the nucleolus of a cell, 
which occurs in the MUlmiw erf the nucleus. The contractile 
vesicles are clear spaces, which contrnct and dilate .it intervals, 
and occasionally exhibit radiating cannts passing into the sur- 
rounding sarcode. Ordinarily one contractile vesicle is present, 
or at raoiii two, but in some cases there may be several. It 
hu also been maintained tliat the contractile vesicles com- 
iBWiicate with the exterior of the hotly, but proofs are wantii\g 
OD Ibb poinL Whether this sAoti/d iiltimatcly be estaAiVish^ 




72 




MANUAL OF ZOOLOGV. 



or not, there cao be little doubt but that the vesicles arc 3 1 
mcnlary form of vascular apparatus. Others, however, 
with some pro])abitity, that the contractile vehicles are to be| 
rei^arded as excretory in function, and that thejr correspond • 
more with the water- vrucular (yslcm of the Annu/cida than 
irith the Inie blood-vasctilar system of higher animals. Certain 
otlicr spaces termed " vacuoles " are generally visible in addi- 
tion to the coniractiic vesicles. These, however, are probably 
merely collections of water surrounding the particles of ingested 
food, and performing with Ihcm a circulation in the abdominal 
cavity, something like the circulation of granules which is seen 
in certain vegrtalile cells. It w:is the appearance of these 
" vacuoles "—which are certainly not permanent organs of any 
kind— which induced Khrenbcrg to term the /n/uioriii the " Poly- 
gnslrica," upon the belief that they were so many stomach.'!. 

Paramaduttt obtains its food by means of the currents of 
water which arc set up by the consiantly-vibrating cilia. The 
nutritive particles thus brought to the mouth pass into the 
cenind abdominal cavity, along with the contents of which 
thev undergo the circulation above spoken of. Indigestible 
ana fsecal particles appcjtr to be expelled by a distinct anal 
aperture, which is situated near the mouth. 

Reproduction in Paramatdum is ctfected either non-sexnally 
by fission (i.e., by a umple division of its substance), or by a 
tr\ic sexual procew. In thi.i latter method two Paramttda 
come together, and adhere dosely to one another by their ven- 
tral -dirfacci. The " nucleus," which is truly an cvafy, enlarge^ 
and a number of ovules are formed in its interior. In like 
marnci, the " nucleolus " of each, which is really a ifitU or iptr- 
tuarium. also enlarges, and develops in its interior a number 
of fiiiiform or rod-like bodies, which arc believed to be sperma- 
toioa. The nucleolus of each then posses into the body of 
the other, tlie act of iranKfercnce being effected through the 
mouth. Contact of the tvLO rqirodut-tive elements then takes 

f)lace, and a number of germs arc produced, which, after their 
iberation from the body of the parent, are de^'cloped into adult ^m 
Paramaaa. H 

Vertkella {fig. ii, ^0 is a beautiful flower-like Infusorian ^ 
which is commonly found in fresh water, adhering to the 
stems of aquatic plants. It consists of a bell-shaped body or 
" calyx," sup[)orte<l upon the extremity of a slender conlnctile , 
Stem or "pedicle." 'ITte other extremity of the pe<liclc iS 
fixed to some foreign body, and iu power of contraction is tlue 
to the presence in its interior of a spiral contractile fibre. 
wbi^ is sometimes called Vhe " stum-nutcle." The edge of 



PROTOZOA: INFUSORIA. 

ihe bell or caJyyt a surrounded hy a projecting rim or border, 
colled the " peristome," wiihin which n a drctilar tturiace, the 
"dUc," forming the upper extremity of the so-called "roialory 
organ." The di&c is surrounded by a fringe of vibratile cilia, 
aing 1 spiral lire which is prolonged into tlic commcnce- 
of the digestive canal. Near ihe edge of the disc is 
itcd the rooutlt, which conducts by ita cniraiice or " vesli- 
xm " into A fiisiforrn canal or " phar^'nx," which terminates 
iiplly in the abdominal cavity. The |i3iticles of food are 
in at the mouth, descend through the short alimentary 
1, and mICT the abdominal cavity, where they are subjected 
the general rotation of the " chyme-mass," being finnliy 
xcrctcd by an anal aperture which is situated near the mouth, 
in Paramtttiitm, ilie body in yi>rH<elia is composed of an 
liter " ctiiide," a central " chyme- mass," and an intermediate 
' conical byer," which contains a contractile vesicle and a 
nd-lilce nucleus. 

Reproduction in yortiedla any take place by (i»sion, or by 

ition, or by a ]>roreKs of encyststion and cnd(^noiis 

Uvuiofi. In the liwi of these modes the calyx becomes in- 

aicd in a longitudinal direction^ viz,, from the pedicle to 

he disc ; and the groove thus formed becomes gradually deeper 

the calyx is finally divided into two halves supported 

the same pedicle: On one of these cups a " po9> 

" circlet of cilia is then formetl in ad<lition to the 

' anterior " circlet already existing (». f., a fringe of cilia is 

eloped round that end of the calyx which is nearest the 

bment of the pedicle and furthest from the dbc). The 

(fi^. if,</), thu9 film ishcd with a circlet of cilia at both 

itremities, is then detached, and swims about freely. Finally, 

be amieriar circlet of cilia disappears, and this end of the 

puts forth a pedicle and becomes attached to some 

object. A new mouth is now formed within what 

I Sefore the posterior circlet of cilia ; so that the position 

"and funrtion of the two extremities of the calyx are thus 

reversed. 

In the second mode of reproduction — namely, that by gcm- 

lion— exactly the same phenomena take place, with this 

;Ie difTcrcncc, that in this case the new individual is not 

juccd by 3 splitting into two of the adult calyx, but by 

ms of a bud thrown out from near its proximal extremity. 

. bud is coropose<l of a prolongation of the cuticular and 

layers M the adult with a caecal diverticulum of the 

domiiuU cavity or chyme-mass. It soon develops a jiosterior 

' " of alia, the connwrion with the parent is rapidly coti- 



74 MANUAL OF 200LOCV. 

(triclcd until cnmpletc sefianition ic eflecied, and then 
nroc«s« differs in no Tw.j)cct from that described iU occurring 
in the lissipArous method of Tq>roduction. 

In the third mode of reproduction th« Vorlieelia encysts 
itself in a capsule, the cilia and pedicle disappear, and the 
nucleus breaks up into a number of rounded germs which arc 
ultimaldr hberaled by the rupture of the cyst, and. after a 
riiort locomotive stage, develop themselves into fresh IWli- 
edia. How far ihb process may be truly sexual is not known, 
and no form of unetiuivoc-U sexual reproducrion has hitherto ^ 
been shown to occur in the c^sc of Vorlieeila. ■ 

Epistylit is a not uncommon form of fixed Infiisorian which ^ 
is nearly allied to Vorti^a, and diffen chicHy in the fact that 
the pedicle is much branched, and is rigid and not contractile. 
£piitylis (fig. lo, ii) usually occurs in the fonn of a greyish- 
white nap on the stems of water-plants, or on the bead of 
die common water-beetle, the Dytitnis mar^inalii. It consists 
of a plant-like branching and re-hnLTichinif frond, the stems of 
whicn are quite transparent and faintly .itriated, but ore not 
contractile, though capable of movement from »ide to tide. 
Each branch of the entire colony tcrmin.nes in an oval calyx, 
aiticulated to the stem by a distina joint, upon which it can 
move Irom side to side. The calyces are oval or somewltai 
campanulate, but have the power of altering their <]imensionK, 
and especially of contracting so xs to shorten their anicro- 
posterior diameter. Kach calyx tciminato distally in a 
alightly-elevatcd annular aperttirc, the margins of which an 
rcgitlaily toothed. 1'hc c.tlyx appears to be formed by a 
hardening of the cuticle, and to fonn a distinct case, with a 
double margin, enclosing the animal. The sarcode-body en- 
closed within this outer envelope is of a tighl-biown colour, 
and full of minute granules, with larger food<vacuoles and a 
vrell-marked contiaciile vesicle, whidi contracts and dibtes 
two or three times a minute. The animal can retract itself 
entirely within its cu|>. and can at will exsert a ciliated disc. 
This di«c (fig. to, HS is inversely conical, and acts as a kind of 
phw, and it is provided M-ith two lufls of long cilia, one on 
eadi side. On one side of the promisiblc disc is the oral 
aperture, which is continued by a distinct and well-marked fl 
gullet into a central ill-dcfioed cavity. Both the entrance of™ 
the gullet and the bottom of the central cavity are provided 
with very long, actively- vibrating cilia, some of which are 
almost seiifotm. The entire granular contents of the abdo- 
minal cavity undergo a constant though slow rotation. 

Ciir^Aaium Is another form which is like Bftsfjiis in consist- 1 



consist- ■ 



PROTOZOA: INFUSORIA. 75 

: oTa number of calyces supported upon a bmnchcd pcdJcle, 
t dificTS from Efiilylis and agrees with Vorticdia in ihc fact 
It the pedicle is contractile. 

Sttntor, or the trumpi,-i- animalcule (fig. II, h), is anotlier 
oinmon Infusonao which is closely [elated to Vorlke/ta. It 



i' 



sins of a tnimpct-shaped cal>T(, devoid of a pedicle, but 

sing the jwwcr of .-itUching and detaching itself at will. 

I'hcn dcutchcd it swims by means of the anterior circlet of 

just ss the calyx of I'ortiitlla will, if broken from its 

In yagiiKola {f\g. it, a) the cMctilial struclurc is 

iich the same as in Vertialla^ but ilie body is protected 

s ntemluonoas or horny case (" carapace " or " lorica "), 

ithin whicJt the animal can retire. In tliis beautiful Infu- 

Drian the caraimce li certainly a cuticiilnr secretion, but it 

at the some lime to be quite distinct from the tiue 

atide itself- 

AmoDgsl the stnictuTcs of the Infusoria which require some 
"ee arc the "pigment spot" and the " trichocysts." The 
nent spot is a brightly-coloured solid particle, generally 
of veT>- common occunence in many Infusoria, but of 
unknown function. The " trichocysts " arc vesicular 
lies, o^Mtble of emiitinf; threaiMike filaments, and greatly 
ibling the urticating cell.t of many of the CaUnltrnla. 
' have been detected in Buriaria, m well as in various 
Ihcr members of thb onler ; and they are very like certain 
Fcclls which arc found in the inlegumenl of many PlanariaHS. 

II, Orukr St;tTOBrA. — This order includes a series of In- 
fusoria of a very anomalous nature. In Adnrta, which may 
be taken as the lyj^, tbc body is covered with a numbet 



76 



MANUAL OF 200L0CV. 



of nuliaring filsmentous tubei, which arc ftimlshcd at their 
extremities with suclorisl discs, and arc cjipablc both of cxscr- 
tion and rcaaciion. These retractile tubes both seize the prey 
and serve as vehicles for tlic ingestion of food ; hence the 
term " polystome," or many-mouthed, ha& been proposed for 
the order by Profeuor Greene. 

III. Order Flagei.i.ata. — ThiK order comprises those /«- 
fiu^ria which, Ulcc Peridimum, find their meant of locomotion 
in long, flexible, lash-like filaments, termed "Rn^ella;" cilia 
occasionally bein^ present as well. In some, as m Prrantma 
(fi^ lo, r), there is only a single one of these appendages ; in 
others, as in Anistntma, there arc two flagella ; whilst in liettrv- 
masthc and Plamntma we have forms apparently transitional 
between the CUiala and tlie Flaseiiafa, since both dlia and 
&u;ella are present in tliese genera. In all their other essen- 
tial characters the flagellate In/useria do not dtlTer from the 
more typical membera of the class. In one sinsular form 
{PkaioHtlerium intfsfinale), the organism consists of numerous 
lOoidi, each with a single HagcUum and projecting membranous 
collar, enveloped basally in slimy sarcodc^ so as to form a cylin- 
drical colony. 

NocTiLUCA. — Amongst the numerous organisms which con- 
tribute to the phosphorescence of the sea,* one of the com- 
monest vi the animalcule known as NoclUuea, tlie true pu.iition 
of which has not yet been determined. Il is nearly spherical 
in shape, having an indention, or " hihim," at one side, dose 
to which is Hxcd a long filament, probably used in locomotion. 
The body convists of a "cuticle" and "cortical layer," en- 
closing a central mass of sarcode. Near the filament there is 
a minute oral aperture leading into a short digestive cavity. 
A nucleus and vacuoles are also present. From the presence 
of a mouth, and from its general structure, AixliiiKa should pro- 
bably be looke<l upon as a fbgellaie /n/asorian, but it is placed 
by M. de Quatrcfages amoDgst the Rhiiofoda. 

* The diffniti luininoailjr of the ten li mninly dna to die NutSnta 
miliarii ; bnii iii pirtial lumiDdiity it due (o vxrioui phoipheraceni ani- 
Bwli. Amongit which are Ihe rhyiaiia afrirm/dj (Ihr Pottocuew manHif- war), 
AttiiHi<t,TiinK«M,AnHiiida, &c The auKofphoinhoFCKcaM iivirknuly 
daltd, bclnn nippOKd very |[enerslly lo be cauaeil by ■ ptocfb of dow 
comhuMlon xuUogou In uut which ukei pUce In phuphomt 'ohcn ex- 
potcd ti> the iiiiiio>i^licr«. XJfmt the wh«lc^ however, it >iipean that ihe 
Iihenomenon it ■ riinl ]iidc«m, contiilinK cuontially In tlw canvenioa of 
Mfvooi force (or vitil energy) inlo ti|^I ; jutt ■> the nme (nrce can be 
coDVCited by cetuin fishei into electriciljr. Thii tnuiirunnation onen 
requite* a tpodol appamtni for ili productiooi, but it appcan to b« Mnte- 
{HBsedlbcIol tty ibc callre orsuiiim. 



I 
I 



PROTOZOA : INFUSORIA. 



77 



Affixities of the Infusoria, — Though generally placed 
amongst ihe Prtl^KHi, of which ihey foim the highest division, 
the potition of tlie In/m&ria cannot be looked upon as defi- 
nitely settled. There ii! n growing opinion amongst comiKtent 
•uthontics that the Infusoria thuutU tie entirely removed from 
the Protfioa, and that they should be jjlacwl nmongnt ihc An- 

' miloi4a, having their nearest allies in the Turhellarian Worms, 
If this change be carried out. the Infusoria .ind Roliftra. which 
older naturahsts gronpcd together, and which modem ob- 
urverB have placed widely apart, will be again brought nearly 

j'tofether. If the sponges also should be removed from the 

^Pr^tea, as is roaintAined by some modem obsencis, then 
the entire sub-kii^om of tlie Proloioa would contain only 

' the Gngarinida, Amarita, JWaminifen], and Radiolaria. At 
present, however, there certainly do not appear to be wiffi- 
cieaUy decisive grounds for such a step; and the al^nities ot 

i the ^onpda arc certainly more intimate with the typical 

XXkiaefods than with the CalfnUrala. 



78 



C(ELENTERATA, 



CHAPTER VIL 

THE SUB-KINGDOM C<ELENTERA TA. 

I. CBARACrms at thk Suu-Kingdom. 2. Dn'isiows. 
3. Gknkral Characters of the Hvokozoa. 4. Ex- 
planation OF Technical Terms. 

Thk Eub-kingdom Calmlerala (Frty vtd Lcuckhart) may be 
considered as the modi^m representative of ihc Riidiala of 
Cuvicr. From the Radiaia, however, the Echmodermata and 
ScoUciAa hjLve heen removed to form the AnnuloiJa, tlie entire 
sub-lcingdom of the Pretotoa has been t;iken away, sml the 
Polytoa have been relegated to their jwoj^r place amongst the 
Mcliuifa. DcHiieting theKe mufu from the old RadkUOy 
the residue, comprising most or the Animals commonly known 
as Polypes or Zoophytes, Tcm.iins to constiiule the modem 
CtxUntemta. 

The Cieknitrala may be defined as animals vikoie aiinmtlary 
tanai ammimUiilts fretly with the gaurai eavtty e/ tkt body 
(" samatie eavtty "). The suinlanee tf the My is made up sf 
ttM Juitdamailai membrana — ait outer iayer, ealial fAe " tet^ 
derm," and ait inner- layer, or " endadermT There are ne 
distimt neural and hamal rexitfru, and in the ^tat majority ^ 
the members of the sub-iingJom there are no traces of a nenvut 
system. Pttnliar urtieating organs, or " thread -tells" art tttuaUy 
present; and, generally speaking, a radiate eondition a/ the organs 
is pereeptrile, esfiuiaUy in the tentaeles rtfilh tohuA most art 
prwided. In all the Caslenterata dittintt reprodnftive organs hmt 
betn thatm to exist. By Professor Allman the Calenterala have 
been defined as follows; — "Mimals composed of numerous 
meroKomes (body-segments), which are disposed radially round 
x longitudinal (antero-posterior) axis; frequently with a de- 
terminable antero - posterior and dono-veiitnd plane (bilat- 
eral) ; a distinct body-cavity, which always communicates with 
the outer world throi^ the mouth." 



COELENTERATA : IIVDROZOA. 



79 



The leading feature which disiinguishei the Cabnterata, 
ud the one from whidi the name oT the xub-kingdom is 
derired, is the |>cculiar structure of the digestive system. In 
the Pr«lnea, as we have «een, n motith is only present in the 
higher forms, and in no case is there any definite ioiemal 
cavity bounded by the walls of the body to which the name 
of " body ■ cavity " or "somatic cavity" could be properly 
applied. In animals higher than the Otlatterata, on the other 
hand, there ia not only generally a pennanent mouth, hut the 
walli of the bodv tuuaUy enclose a permanent chamber or 
" body-cariiy." Further, in most caaes, the mouth conducts 
into an alimenUry canal, which is always distinct from the 
body-cavity, never opening into it, but usually passing through 
it to open on the surface by another distinct aperture (the 
anus), In most cases, thcrdbre, the alimcntar>- tanil is a 
lube which communicates with the outer world by two aper- 
tures — a moutli and anus — but which simply pa:ise« through 
the body-cavity without in any way communicating with iL 
In the C^lmlerata there is an intermediate condition of parts. 
I'here is a distinct and permanent motith, and a distinct and 
permanent bodyovity, but the mouth opens into, and com- 
nunicates freely with, the body -cavity. In some cases 
(Ifydrotaa) the mouth opens directly into the general body< 
cavity, which tlien ierrn a a (li{<cslive cavity as well (lig. 
II). In other ca-ies there inier\'cnet tietwecn the motilh and 
the bodv-<avity a short alimentary tube, whith communicates 
externally with the outer world thro;igh the month, and opens 
below by a wide aperture into the general cavity of the body 
{AetiiMiM, fig, li). In no case is there a distinct intestinal 
cual whkh runs through the body and opens on the sur&oe 
by a mouth at one end .uid an excretory aperture or anus at 
the other. 

With regard to the fundamental tissues of the Caltnterala, 
there exist two prinury mcmbrane-s, of which one forms the 
outer snriace of the body, and is called the " ectoderm ; " 
whilst the otltcr line* the alimentarj- c-uul, the general cavity 
of the body, and the tubul.ir tentacles, and is termed the 
" endoderm." These mcmbnuius correspond with ihc primi- 
UTc serous and mucous layers of the germinal area, and be- 
come difli^rentiatcd in opposite directions, the ectodenn grow- 
ing from witliin outwards, the endoderm from without inwards; 
Each constsls of numerous nuclear bodies, or " endoplasts," 
embedded in a granular "intercellular substance' or "peri- 
pbut ; " and each may be rendered more or less complex by 
racuobtioa or fibrillation. 



8o 



MANUAL OF ZOOLOGY. 



In connection with the integument of the Calenterata, the 
o^uis Icimcd " Ihrwid-cells " ("cnidre," or "ncmatocy&is") 
be noticed. These arc peculiar ccUulor bodies, of 
rious shapes, which probably serve as weapons of offence 
J defence, and which commtmicate to mantr metnben of 
the sub-kingdom {e.g., the Sea-blubbers) ibcir well-lcnowQ 
power of stinging. Id the common Hydra the thrcail-ccMs 
connst of "oval clastic sacs, containing a long coiled tilamcnt, 
barbed at its baac, and serrated al»n)( iiii eilges. When fully 
developed the sacs arc tensely filled with iliiid, and the 
slightest touch is sufficient to cause (he rctiovcrsion of the 
filunent, which then projects beyond ihc sac for a distance, 
which is not uncommonly equal to many times the lengiJi of 
the latter,'* — (Huxley.) (Fig. \i,d.) Many beautiful modi- 
fications of shape are known in the tliread-celU of different 
Coelenterates, but their essential »tructure in all cases is much 
the same as in the Hydra. It is only in few cases, compara- 
tively speaking, that the thread-cell* have the power of piercing 
and irritating the human skin \ but even in the diminutive 
Hydra it b probable that they exercise some benumbing and 
deleterious mfluence on the living organisms which may be 
captured as jwey. The Calaiierata are divi<led into two 
classes, termed respectively the Hydratoa and the AetimtM, 

Class I. Hvdroma. 

The Hydro^a arc defined as Ctrtenierata in wAiVA tht walls 
of tht digatht sac art tMl sf/anitei from thai of Iht ^wral 
tod/-{ajfity, the /Ki' ceintidtHg with one ancthfr; iht r/produc- 
lipf wjptw are m Ike fsrm oj external proeeises ef the Ivdy-waU. 
(Fig. iJ.a.A) 

It follows from the above, that, since there is but a single 
internal cavity, the body of a Hydrotoen on transverse section 
apiicars as a sin^e lube, the walls of which are formed by 
tlie linnts of the combined digestive and somatic cavity. 

The Hydrvtoa are al) aquatic, and t)ie great majority are 
marine. The class includes both simple and composite 
uiganisms, the most £uniliar examples being the common 
Fresh-water I'cilype {Hydra), the Sca-firs (Sertu/arida), the 
Jelly-fishes {Aftdma), and the Portuguese man-of-war {Pky- 

* Tbitail-cellt. Ihouffh very commocly, if not unlvcmiUy, pTc*enc in the 
Ca/fHlimU, arc ncvtnhclcu not peculiar to (h«in. Similar or^ni hive 
been Bhuwn to «ii>>t in tevcral of ice .ViUthvaehialt MetiaifO, «t well as in 
tome Anncliiln [.^v jfrtuvrHu), Tlierr likrwiw cxiti uialosou organ* 
(tririM^ei) in leveril of tlie /n/mithi.t, wi in tlie PlaHariJa. 



I 

01 organ* ^ 



OELENTERATA : HVDROZOA. 



8l 



■ 

r^Ww). Owing to the peat difficulty which ia ordinarily 
I experienced by the student in roaMerinf; ihe details of this 
I cUss of animals, it has been thought aitvi^ble to introduce 
here a &hort explaiutioD of some ot the technical tenns which 
! are in luoie general use in describing these organism. 

Gknexal Tbruinolocv or the Hydkozoa. 

/ndhiJnai, — We hare alrea<ly seen {see Introduction) that 
the term "individual," in its zoological sense, must be re- 
stricted to " the entire result of the develoi)ment of a single 
fertilised ovum,* an<l that in this Knse an individual may 
cither be simple, like an Amarba, or may be composite, like a 
Sponge, which it piroduccd by an aggregation of amoibifonn 
pojtiaes. If all the parts composing an individual remain 
mutually connected, its de^-clopmcnt is said to be " continu- 
ous ; " but if any of these parts become separated aa indepen- 
dent beings, the case becomes one of "discontinuous" de- 
vdo^ent. We have seen, also, that however long zo&idal 
multiplkalion may go on, there ultimately arrives in the history 
of every individual a jjcriod at which sexual reproduction must 
be called in to insure the perpetuation of the species through- 
oot time. 

Amongst the Jfydrotifa, the individual may be either simple 
or compound, and die development may be cither continuous 
or discontinuous, the following lenns being employed to de- 
note the phenomena whi<:h occur. 

Hydntevta. — This is the term which \i employed to desig- 
nate the entire body of a Hydroioen, whether it be simple, as 
in the Hydra, or composite, as in a Srriuiarian, 

PoiypUt. — The alimentary region of a I/ydrvitwn is called 
a " polypite ; " the term " polype " being now restricted to the 
same region in the Adiiuua. In the simple Mydrotoa the 
entire organism may be called a " polypite ; ' but the term is 
more appropriately applied to the separate nutritive factors 
which together make up a compound Hydretomi. 

Distaiand Proximal. — Thcie are terras applied to different 
extremities of the hydrosoma. It is found that one extremity 
grotra more quickly than the other, and to this frce-growinx 
end — at which the mouth is usually situated — the terra " distal ' 
is sppUed. To the more slowly growing end of the hydtosoraa 
— which ii at the same lime usually the fixed end — the term 
"proximal" is applied. Tlicse terms may be used ciihcr in 
relation to a single potj-pite in the com[jound Jfydrtnca, or to 
the entire hydrosoma, whether simple or compound. 



82 



MANUAL OP ZOOLOGY. 




Ccausare. — This is ihe lenn which n employed to dcsigiute 
UlC common mink, which unites the scparaic polj'pites of aiiy 
compoimd Hydroioen into a single oiganic whole. 

Polypary. — The term "potypaiy" or "polypidom" is ap- 
plied to the homy or chiiinous outer oovering or envelo]>e 
with which romiy of the Ilydroitia are furnished. These tcmu 
have also not \in(:(imnionly Ijceri applied to the very limilar 
structures produced by the much more highly organised Sca- 
nutts and their allies {Po/ysoa), but it is better to restrict their 
IDC entirdy to the Hydrtaea. 

ZoStdt. — In continuoui development the partixlly inde- 
pendent beinga which arc produced by genunation or Assion 
by tlie Tiiiinitive organism, to which ihey remain permonentl/ 
atiached, are termed " zooids." 

In discontinuous development, where ceruio portions 
the "individual" arc separated as completely independent 
beings, these detached portions are likewise termed " zooids ;' 
that which is first formed being distinguished as the "pro 
duciDg looid," whilst thai which separates from it is kno« 
AS the "produced looid." In a great number of f/ydrt<tfft\ 
there exist two distinct sets of zouids, one of which is destined 
for the nutrition of the colony, and has nothing to do will 
generation, whilst the functions of the other, as far as tha 
colony is concerned, are wholly reproductive. For the wMt\ 
asitmbiagt ef Ihe nutritive teoids of a HydroteM Professor Alt 
man has proposed tlie tenn " trophosome," applying the tenn 
" gonosome ' to the entire iisiemilage of Ihe rt^oduetife uoidt. 
In such HydrQzaa, therefore, as pai,sei8 lliese two distinct sets 
of tooids, the " individual," zoologically speaking, is compared 
of a trophosome and a gonosome. It follows from this that 
neither the trophosome nor the gonosome, ho»-ever apparently 
indejienilent. and though endowed with intrinsic powers of 
nutrition and locomotion, can be looked upon as an " indwfl 
vidual," in the scientific sense of this term. As a nde, theS 
tooids of the trophosome are all like one another, or are 
"homomorphic;" but there arc some rases (as in Hydrac 
tinia, and in the ncmatophorcs of the Plumularida) in which 
some of the looids of the trophosome arc unlike the others. 
The zooids of the gonosome, on the other hand, arc normally 
unlike, or are " beteromorphic," consisting of t«-o or three 
different sets ofzo^ds, each with its special duty in tlie gene^ 
ative functions of the Hydroid Colony. 




CCELENTERATA : inTlROZOA. 



CHAPTER VIH. 

DIVISIONS OF THE HVDROZOA. 

Sub-class Hvoroida. 



8* 



^^HE Jffyttrptaa arc divided into four sub-cluscs — rti., Ihc Ifj- 
Jroida, the SifiA^wfiA^ra. the Liuemarida, and the Discsfhera, 

Suit-cLAss I. HvDRoiDA. — Thifi sulxJass comprises those 
JlyJntuti whkk amstit 0/ an aJiinettlary rtgion or "polypiU," 
fehUh it prmidtd tetth an adktrent disc or " hydrorhisa" and 
prthttuik taUadet. 

In some fevr cases the hydrosoma is composed of a xtngle 
polypite only, as in the HydrUa and in some of the Corynida; 
but usually there arc scverd polypitcs united together by 
means of a common tnink or "cQ:nosarc,"as in most of the 
C^ryntdii and in the orders Srritt/aridit and Cam/>anu/ijrida. 
Fuithcr, in the great majority of cases the "hydjorhiia" is 
perautnently attached to some foreign object. 

The Hy4r»ida comprises four orders — vit. the Hydrida, the 
Corynida, the Sertu/arida, and the Campantdarida, 

Ordek I. Hvi)Rii>A {Gymno(kroa, Hincks), — This order 
connprises those Ifydrotoa whoie " hydrosoma " amisti of a 
li^git iot9molitt fo/y/rife, witA tentad(S and " hydrerhita" and 
mtk rtfrsduHKt orgam Vihiih appear as simple txttrnal pro- 
ttsses of the body-waU. The hydrerhiut is discoid, and no heird 
(Ktieu/ar layer is at any time detWaped. 

The onler Ifydrida comprises a single genus only {Hydra), 
ineluding the various species of " Fresh-water Polypes," a» 
they are often called. The common Hydra (fig. la, c) is 
found abundantly in this country, and consists of a tubular 
cylindrical body, the "proximal" extremity of which is ex- 
panded into an adherent disc or foot — the " hydrorhiaa " — ^by 
meaiu of which the animal can attach itself to some foreign 
body. It possesses, however, the power of detaching the 
hydtorhiza at will, and thus of changing its place. At the 
opposite or " distal " extremity of the body is placed the 
mouth, surrounded by a circlet of tentacles, which an^e a 
tittle distance below the margin of the oral aperture. The 
lentada vary in number from five to twelve or more, and 
they vary considerably in length in different spedes, being 
much shorter than the body in the Hydra viridis, but being 
extretnely long and lilamentoiit in Hydra /uim. Thcj- arc 
hijlfly eaieosile and contractilei and serve as organs of pre- 



«4 



MANUAL OF ZOOLOGY. 



endcdH 



lienston, being capable of rctrnccion till they appear »» nothi] 
more than so many warts or tubercles, and of being extendi 
to a leiiKili which is in some £|>ccies many times longer than 
the body itself. (In the Hydra fuica the tentacles can be 
pronuded to a length of more than eight inches.) Each 




Fh. ri — M<>riihi>lntv dF Hrd'MOi. « Oltzniiinuiic Hciian ot Hydra. TYb iiA 
IIiM.ii Ibc cciddsmi. ihc fill? lini anil ffeai tfiKc ■^■(tin an Ih* «adadcnBi 



^ HfJrit virutii, ahcrvmc 
tamti (I 



■ixfle ovum enniaiiial id fin bodiMnll iwv iba 
rnsbiul (itrimitr, mi ivu rioiiioni ommlnlnc ipinTuMiUMB ih* kun <* 
ihc i«ntMl«: ■■ Hfrl^ rirtcrii, viih ju uBdEU(h«) bwl 1 ^Tlnailatl ef u. 
Hydnit gfcatly m f n ificd. ■ 

KSb of a proloni^ation of botli ectoderm and cndodcrm. eiv- 
cloting a diverticulum of the suniati<: cavity, and they xn: 
sbatutontly funiishcd uith thTcad-cellx. 'Die cylindrical hydro- 
soma is excAv.iRfl into a single large caviiy, lined by the cn- 
dodcrm. and communicating with the exterior by tlic mouth. 
This — the " somatic cavity " — is the sole digestive cavity with 
which Uie Hydra is provided, the indigestible portions of 
food being rejected by the mouth. 

The Hytira po3.4essea a most extraordinary power of 
ing mutiUtion, and of multiplying artificially when tnechant 
cally divided. Into however many jiicce* a Hydra maybe 
divided, each and all of these will be develoiied gradually into 
a new and perfect polypite. The rem.iikahle experiments t& 
Trcmblcy upon this subject arc well known, and have been 
often repeated, but space will not permit further notice of 
ihcm here. Reproduction is effected in the Hydra both 
asexoally by gemmation, and sexuiilly, — the former proccst 
being followed in summer, and the latter towards the com- 
menremcnt of winter, few individuals surviving this sexson. 
In ihc first method the Hydra throws out one 0* more buds. 
geacratly from near its yioximat extremity. These buds tt 



rcsistfl 
chanlV 




OELENTERATA ; HYPROZOA. 



85 



first consist simpljr of a tubular prolongation of the ectoderm 
and endodenn, enclosing a cxcal (iiveniculiim of the body- 
caviijr ; but a mouth and tentacle* are soon developed, when 
the new being is usually detached as a jicrfect independent 
Hydra. The Hydra thti§ produced throw out fresh buds, 
o^en before they arc detached from (he parent oig.mism, and 
in this way reproduction is rapidly carried on. 

In the second or sexual mode of reproduction, ova and 
spennatoioa are produced in outward processes of the body- 
wail (fig. 13, h). The spermatozoa are developed in little 
conical elevations, which are jiroduccd near the luiso of the 
tentiides, and the o>'a arc enclosc<l in sacs of much greater 
siie, situated nearer the fixed or proximal extremity of the 
animal. Ordinarily there is but one of these sacs containing 
a single ovum, but sometimes there arc two. When mature, 
the ovum is expelled through the body-n-all, and is fecundated 
hf the spermatozoa, which are simultaneously liberated. The 
embryo appean as a minute, free-sn-imming, ciliated body. The 
lerous ftiM mucoiu Inyen of the blmtodenn (gcnninal area) 
eorrespond to the ectoderm and cn<lgdcrm, and for [lie forma- 
tion of the perfecl Hj^ra nothing further seems w.-inting than 
tHc modification of one end of tiic body into a hydrorhiaa, and 
the fomution of a mouth and tcnioclcs at the other. 

Okdbii II. CoR^-NiDA ( = TuflULARtDA, the AfAecota ai 
Hincks). — The order C^ynUa comprises those Hydtvzoa 
wAeu hydrotema is fixed by a hyJrorkiia, and amiiilt eilktr of 
a tinj^t peiypite, er ^/ teveral uHtted by a amesnre, xffiich usually 
dtithfs a firm etdrr lay/r or " felyfvtry." No " hydrolhtea' 
art prrstnt. " Tht rrpriduetit'e organs are in tAe form o/gona- 
fA^rts, toAi/A t>ary mucA in ttriutHrt, and arist from the sida of 
Uup^yfitei,from thtexnosare, or fr^m goneblastidia" — (Greene.) 

The hydroeoma of the Ctwynida may consist of a single 
polypite, as in Corycmarpka and Vortidava, or it may be com- 
pOMd of several united by a coenosarc, as in C^dylophora 
(fig. 13, «). The order is entirely confined to the sea, with 
the single cxcqrtion of Cordylofihora, nlii<h inhabits fresh 
water. In TUbularia and its allies the organism is protected 
by a well-doelopcd external chilinoits envelope or "poly- 
pary;" twit in the other genera belonging to the order the 
pcdypary is either radinicnt.iry or is entirely absent. The 
poljrpar)- of the Carynida, when present, is readily distinguished 
from that of the Sertularida, by the fact that in tlie former it 
etteods only to the tase of the polypiles ; whereas iu tlie latter 
it expand* to form linle cups for the reception of the polyjiites, 
diesc cup« being called "hj'drothccat" 



86 



MANUAL OF ZOOLOGY. 



As regards the rcpToduciive process in the C^rynida, thel 
teptoductivc dements are devdoped in distinct buds or mlcs,J 




I 



Ftf' t) ^^Ofpha1o(7 of ConmidL it PncDoil of C*r4yitfkm hvmUri^ % 
«BUrc*d 1 1 rntmroi gf iiic fuw tantMHablr MbtsM, (liDvlna a paM 
thncsoiiDiihDreiin dlAeRnlMunafKiwili. >iiclMa<MCDH*iolnf ava : f I . .. 
af ^>«'fv7W S-Mtni triih nAduioFbnn by^id* bu^JJag nvA bilvicD llic IcvUcib. 

wliich iLTc exlcmnl i>rDC«9«es oi t)ie bod)r-waII, and have beeaB 
■pily termed "gonophorcs" by I'rofcssor Altman. StHctlyfl 
speaking, Dr Altnuin understands by the term "gonophorc 
only the ultimate generative ::ooid, thai which immnfiatr/y pro- 
duces the generative elements. Uicat variations exist in tliei 
finrn and devdoproent of these generative buds, and an exami-J 
nation of iheae leads us to soine of the moit singubr phcnc^] 
mena in th« entire animal kingdom. In some species of] 
HyJrottmia and Cfrym, ihe generative biids or "gonophorcs* ' 
exist in their simplest form— namely, as sacciform |)rotuber- 
ancGS of the endoderm and ectoderm, endowing a diverticulum 
of the somatic cavity. In this form the)* arc attached to the 
" trophosome " by a short stalk, and they arc rcrnicd " sporo- 
sacs" (fig. 14, a). They are exactly hkc the buds which we^ 
have already seen to exist in the Hydra, with this difference,^ 
that (hey are not themielvea developed into fmh polypites, 
but are simply receptacles in whidi the essential dements of 
generation — the ova and spcrmatoroa— are tweparetl, by tha " 
union of which the yotmg Ccryniii is produced. 

In CorJylaphara (fig, 13, i) a further advance in stnicture tsl 
perceptible The gonophorc now consists of a closed sac, 
from the roof of which depends a hollow process or jwdunde 
— the " nunubrium" — which gives off a system of tubes which, 
run ia the mils of the sac For reasons which will be 
diatety evident, the gonophore in this case is said to liave 
"d/i^iscd " medusoid structure (fig. 14, b). 



of 




CCELENTERATA: IIYDROZOA. 



87 



Id certain Cfrytida, however, wc meet with a ttiti higher 
form of stniciurc, the gonophores being now said to be 
** niedusoid." In these cases Uie gcDuative bud is pnmitivel)' 
» simple sac — such as the "sporosac" — but utlimalel/ devel- 
ops itself into a mudt more complicated structure. The 
gonopbore (fig. 13, 1-) is now found to be compMed or a beU- 
shaped dltc, termed the " gonocalyit," which is attached by its 
base to the parent otganism (the trophosome), and has its 
cavity turned outwards. From the roof of the gooocalyx, 
like the clapper of a bell, there depends a peduncle or 
" nuuuibrium." which contains a process of the somatic cavliy. 
The manubiium ^ivcs out at its fixed or proximal end four 
prolongations of its cavity, in the form of radiating lateral 
tubes, which run to the margin of the bell, where tlicy com- 
municate with one another by means of a single circular canal 
which sujTOuiuls the mouth of the bell. Ilii^ system of tul;es 
oonstitutei what is known as the system of the " gonocalycine 
canals." The gonophorc, thus constituted, may remain jicr- 
ottnently attached to the parent organism, as in Titl-ularia 
indmsa (fig. 14, t); but in other cases still further changes 
In the higher forms of development (fig. 14, d) the 




T* 14,— R«f(<>d<Kli>« p itc mn el Hrimaa. t Siwrniu : h Diicuiud maliiuirt : 
4 J^<ach«d ■odinilHn niiDphcm : d F»c ntnluiirnrin innnphr.r«, 'IW tj<tv. vhi^). 

'1 iaJiom <Im only g( Ihc mauuLviuni ami ihe nonucalrdiit ouJi. 



manubrium acquires a mouth at its free or distal extremity, 
and the gonocilyx becomes detached from the parent. The 
^nophore is now free, and behaves in ei'ery respect as an 
inckpendent being. The gonocalyx is provided with mar- 
gbal leaucles and witli an inward prolongation from its 
margin, which partially closes the mouth of the bell, and is 
(cnncd the "veil" or "velum." By the contractions of the 
gonocalyx, which now serves at a natatoriHl organ, the gono- 
phore is pfopelled through the water. The manubrium, with 
the shape, assumes tlw functions of a polypite, and its cavity 
take* upon itself the otBcc of a digcistive sac Growlti \s 



88 



MANUAL OF ZOOLOGT. 



antic fl 



nptd, .ind the gonopliore may attain a comparalivctf gifantic 
siie, being now abioiutely idenltcal with one of lUosc organ- 
isms which .ire tominonly called "jelly-fishes," and aie tech- 
nically kno*Ti as Afedttsa (fig. 15). In buO, u we shall after- 
waids Kc, most if not all of the fymntfhiMalmaU Meduta, 
onfall)- described as a distinct order of free-swimming l-ly- 
drozoa, are in tnith merely the libcnttcd generattre buds, or 
" medusifoira gonophorcs,'' of the jtcrmancnlly -tooted HyJiviiis. 
Finally, the cascniial generative elements — the ova and spcr- 
miLXOiaa. — arc developed in the waits of the manubrial sac, 
between its endoderm and ectoderm, and embryos are pro- 
duced. These embryos, however, instead of resembling the 
organism whii-h immediately gave them birth, develop them- 
selves into the fixed Carynid from which the gonophorc was 
produced, thus completing the cycle. 

As we have seen, the generative 
buds of the Csrynida may exist in 
the following form*:— t. As " sporo- 
sacs," or simjitc do),ed sacs, con- 
sisting of ectoderm and endoderm, 
with a central cavity in which 
ova and spermatozoa arc produced. 
i. As "disguised medusoids," in 
which there is a central nianubrial 
process and a rudimentary system 
of gonocalycinc canals; but the 
gonocalyx remains close<l. 3. Ai 
complete mcdusoids, which have a 
central manubrium, a complete sys- 
tem of gonocalycinc canals, and an 
open gonocalyx; but which never 
become detached. 4. As perfect 
medusiform gonophores (fig. 15), 
which are detached, and lead an 
independent existence for a time, 
until the generative elements are 
matuic(L in whichever of these 
forms the gonophore may be pre- 
sent, the place uf its origin from the 
trojjiosome may vary in different 
specie* of the oixIcT. 1. They may 
arise from the sides of the |>o!jq»ites, 
•sin Cwynti.tiAStaHriJia; 2. Theymaybeprod«cc<l from the 
coenoKirc, as in Cerdyloph&ra ,■ 3, They may be produced upon 
certain special processes, which are tcrm«] " gonoblastidia," 



I 




I 



rtl. IV — Fix meiiMJftnii wtnc~ 
■bn U Cfytia Jj*namild»m 
nuAA m CcDInI pulypilt or 
buiAmoi : M lUdutliBt Rulr*- 
TucuUraiul* ; c Omlar<Aiu] ; 
m Utrthul lndii>i rTmucki 





com 

tOK 

■ifaat 

■oTth 






CfELENTERATA : HVDROZOA. 



u io Hydratiinia and DUeryne. Thete gonoblutidia are 
procesMS from (he bodyw-all or cwnosarc, which closely re- 
semble tnie pc>I)rpilc3 in form, bt;t difTcr Trunt Ihcm in being 
anally devoid of a mouth, and in having ^honcr tcnuclcs. 
As regards the dcvclopmcni of the Corynida, ihc embryo is 
generally, though not always, ciliated at first, and be- 
comes developed into a hydra-fomi poly|iile, which fixex itself 
to sone fareign body, and then (if not bclunginj; to one of the 
simple rorms) proceeds to produce by genimnlion the com- 
— site aduh. 'ITic development of the Corynida (as well as 
t of the StrtuLtrida and Lwtmarida) obeys the general law. 
I the new polypiles arc dcvclojicd at, or near, the distal end 
the hydiosoma ; so thai the distal polypiles aic the youngest, 
the reverse of this obtaining amongst the oceanic ffydrotoa. 

The subject of the reproduction of the Corynuta having 
been treated at some length, so as to apjily to the remaining 
Jfydroida, we shall now give a brief 
dcBoiptioD of the two leading types 
of stnictare exhibited by the order. 

Sudrndrium, a genus of the Cory- 

Hi/fa, which is not uncommonly 

found attached to submarine ot>- 

leciN, usually in tolerably deep 

ter, may be taken as a good 

xample of the fixed and composite 

division of the order. 1'he hydro- 

soraa consists of numerous polypites, 

united by a oocnosarc, which is more 

less branched, and is defended 

a homy tubular polypary. The 

lypites are borne at the ends of 

branches and branchlets, and 

not conuined in " hydrotheae," 

poly]»ry ending abru]>lly at iheir 

The poly|iites arc non-rc- 

ile, of a reddish colour, and 

led with about twenty ten- 

arranged roimd the mouth in 

■ingle row, Ttdmiarta (lig. i6) is 

CTT similar to Eudmdriun*, but the 

iydro«oma ih eitlier undivided or is 

eiy slightly bnuKhed. The hydro- 

ima consists of clustered horny 

ibes. of a straw colour, and not unlike straws to look at ; hence 
conitnoo name oi pipe<viaUiDe given to this zoophile 



wfit 




7Wik£arM im4Jt*iM, lutunl 



ldl& 



90 



MANUAL OF ZOOLOGY. 



■ 



Each tube is filled with a sort, scmi-6iiid, reddish cccnosarc, 
itod gives exit at its distal extremity to a single polypitc. llic 
polypites are bright red in colour, And are not retractile within 
their tubes, tlic horny polypary extending onty to their bases. 
Tlie polypites ore somewhat conical in 5liai)c the mouth being 
placed at the apex of the cone, and they ate furnished with 
two sets of tentiicld. One set consisU of numerous short 
tentacles pUced directly round the mouth ; the other is com- 
posed of rrom thirty to forty tcnLiclcs of much greater length, 
arising from the polypitc about its middle or Dcar the base. 
Near the insertion of these tentacles the generative buds ue 
produced at proper seasons. 

Ceryomffrpha nutam may be taken to represent those Cwy- 
nida in which there is no [Kilypary and the hydrosoma is sim[»Ic. 
It \% about four inchet in length, and is 6xed by fiUmentous 
roots to the sand at the bottom of the sea. It consbts of a 
single whitish poly|>ite, striped with pink, and terminating 
upw.irds in a pear-shaped head, round the thickest part of 
which is a circtcl of from fort>' to fifty long while tentacles. 
AbOTc these comes a scries of long branching goDoUastidia, 
bearing gonophores, and succeeded by a second shorter set of 
tentacles which siinoiind the mouth. The gonophores beconvc 
ultimately detached a.s frce-swiniming mcdusoids. 

Orui^k hi. Sp-KTUUkioa {Th^tphora, HIncks). — This 
order comprises those Hydroxoa " whose hy^rosoma U fixtd 6y 
a hydrarkiM, and eoniUti of saxral polypita, proteei(d hy hydrt^ 
th^, and (cnnfttfd by a (irtutiart, U'fttch is usually bran(/ied and 
im-eiteii by a :Yry firm ouler hyer. Repr^uetivt organs in tjte 
Jffrtn f/ lymfphores arising fri/m the eanoiarc or /ram gmuMSas- 
/«/w."— (C.reene.) 

The Serlulanda resemble the Corynida in becoming perma- 
nently fixed after their embryonic condition by a hydrorhiza, 
which is develnpe<l fiom the proximal end of the cixnosarc ; 
but they differ in the fact that the polypilcs are invariably pro- 
tected by " hydrothecn," or little cup-like expansions of the 
polypatj- (fig. 17, i7, b) ; whilst the hydrosoma is in all cases 
com|>o<ied of more than a single polypitc. The ccenoaarc 
generally consists of a main stem — or •' hydrocaulus" — with 
many branches ; and it is so plant-like in appearance that the 
common Sertultrians are alniost .itways miskiken for sea-weeds 
by visitors at tlie seaside. It i.s invoted by a .iirong corneous 
or chiiinoiis covering, often termed the " periderm." 

The po!)-pitcs arc sessile or subKssilc, hydra-form, and ia all 
esaentijd rejects identical with those of the Cerynida, though 
usaaliy smaller. Each polypitc consists of a soft, contractile. 



I 



I 



A 



C<ELENTERATA : HYDROZOA. 



9» 



rextensilc body, which is famished at its disul extretnity 
ritfa a mouth ,ind a circlet of prehensito tL-ntaclcs, richly fur- 
lished with thicad-cells. The tentacles have an indistinctly 
Jtern^e arrati^etnent. The mouth opens into a chumtier 
vhich occupies the whole length of the polypite, and is to be 
_ 4ed as the corohined body-cavity and digestive sac At 
fits lower end this chamher opens hy a con.ttricted aperture 
' MO a tubular cavity which is ei'crywhere excavated in the 
ubstance of the cceoosarc (fig. 17, i). 1'he nutrieat panicles 




Fit IT '~-<> Sirtiitimt IDj/iAMia} M*imM. Duninl iIh; if rnginetn at (lie Hume 
««liui«d, <viTtnf ■ luXe opHilt Ia ■'^^ nlt^wmc the hj^lroihcc* (A): t rr^iAmcnt 
of CMit^KnterH *fffrsM (aJUr ]lmfLi\ &>i<rwin£ th* polypiU* cmwrmj in thtir 
hr^pflhtotUX fi hlhr Ifrt ^uiiil ■! vhfc^ ijbe cttDOMH ««ina)UAkcAt<4 vilh Iht 
eh«r(fccra)T*ilc1r) 

lined by each polypite thus serve for the support of the 
irhole colony, and are distributed throughout the entire 
"Duusm. 1 he nuiiiiive fluid prepared in the interior of each 
jypitc gains access through the above-mentioned aperture to 
the cavity of the ooenosarc, which by the combined exertions 
I of the whole assenibla^ of polypiics thus becomes filled with 
granular nutritive liquid. This cccnosarcal fluid is in con> 
Hi movemetit, circulating through all parts of the colony, 
ad thus maintaining its vitality, the cause of the movement 
iMing probably due, in part, at any rate, to the existence of 
ribrating cilia. The generative buds (gonophores or ovarian 
Ivcsidcs) arc usually supported upon gonnhla-itidia, and seldom, 
"" ever, become detached in the tnic ijcrlulaiids. TVicy m« 



93 



MANUAL OF ZOOLOGY. 



often developed in chilinous receptacIeK known as "gono- 
thccc" (fig. 17, f). The young Sertulori.iii on ctdptng from 
the ovum apt>crars a» a Irtfc-snimmin}; ciliated body, which 
soon lo^cs its cilia, fixes itself, ^nd develops n yoimg cccnosaTC, 
by gcnimanon from which the branching hydrosoma of the 
perfect organism is produced. 

In Piumularia and some of its allies there occur cerlaiii 
peculiar organs, probably otfensive, to which the name of 
** neniatophores" hxs been applied. Each of these conHixts of 
a process of the ccenonrc, which is invested by the homy 
]]Ol)'pary, with the exception of the dist-il extremity, which 
remains uncovered, and contains many large thread-cells em- 
bedded in iL 

Okdek IV. Camtanularida. — The members of this order 
arc closely allied to the Sertulitridix : so closely, indeed, that 
they are very often united together inio a single groups The 
chief difference consists in the fact that (lie hydrotliecK of the 
CompoMuJarula with their contained po1y|>itcs are supported 
upon conKpicuous stalk-t, thus being terminal in (wsicion (fig. 
' 7. *) i whil.st in the Sfrtuhirida ihcy arc sessile or subsesstc, 
and aic pUced laterally upon the branchlcts. The gonophores 
also in the Campanularida arc usually detached a$ free-swim- 
ming medusoids, whereas lliey remain permanently attached 
in the Sertuiarians. Each medusoid consists of a little trans- 
I>arent ^ai»y bell, from the under surface of which tliere is 
suspcntKd a modified polyinte, in the form of a "manubrium" 
(fig- '5)- Tfie whole organism swims gaily through ihe water, 
propelled by the contractions of the bell or disc {gowca/jx) \ 
and no one would now su&pcct that it was in any way related 
to the fixed plant-like zoophyte from which it was originally 
budded off. The central polypitc is fiimishcd *-ith a mouih at 
its distal end, and the mouth opens into a digestive ^ac. From 
the proximal end of this stomach proceed four radiating ciiuls 
wliich extend to the circumference of the disc, where tliev nit 
open into a nngle circular vessd surrounding the mouth of 
the bell. From the margiiu of the diiK hang alMi a number 
of delicate extensile filaments or tentacles ; and the circum- 
ference is stilt further adorned with a scries of brightly-coloured 
spots, which are probably organs of sense. The mouth of the 
bell is partially closed by a delicate transparent membrane or 
shelf, the so-ailed " veil." 'I'hus constituted, these beautiful 
little beings lead an indepen<leiit and locomotive existence for 
a longer or shorter |)eriod. Ultimately, the essential elements 
of reproiluciion are de\eloi)ed in -Mierinl organs, situated in 
the course of tiic radiatiiLg canals of the disc. The Tcsulting 



\ 



I 
\ 



A 



C(ELESTERATA ; HYDR020A. 



93 



Fembrym are c!lUt«d and &ce-swimming, but ultimately Gx 
I ihcmNclviM, and develop into the plant-like colony from whidi 
' frtsh m«dtuoi(b may t>e biidde4l off. The ova in the niedusj- 
[fonn gonophorCM arc iisiiAlly develO|>e<I in tlie coune of the 
f gQOor.ilycinc 4.ftnal«, and not between the ectoderm and 

cndodcrm of the maniibnum, as it the case in the Cerjrnijfa. 

Examples of the order arc Campanularia Laomtdca, &c. The 
I dijtinctionii between the SertularUa and Coftpanularida arc 
kcertaiiily in«it)idenl to justify their being placed in separate 
tonjem. If united together, it would probably be best to adopt 
[the name T^aphera (HinL-ks) for the order, and to emjiioy 
llhc names StrtttUtrida and Campanularida for the sub-orders. 



CHAPTER IX. 






All 



SIPHONOPHORA. 

SttBKXASS II. SiPKoKoPHORA. — The members of thin tub- 
constitute the so-called "Oceanic Hydroioa;" and arc 
•tcrised by the po»xe»ion of a "/m* and ocfanic hydro- 
toma. (itttittiig of ifi'fral poiypius ttnittd by a jitxible, (antral- 
tiU, ttHbranthrJ or slisfulybranfhni arn^arf, the pruximaJ otd 
tfv/hUk is vttiaify /umis/ifii wUA 'neaocalyta,' atui it dUafed 
a ' sfimattKytt^ ffr into a 'ptuumatof/urf.'" — (ttreene.) 
" the Sipiicn^ora arc unattached, and permanently free, 
all are composite. They are singularly lielic^-ite organisms, 
ly found at the surface of tropical sea.s, the Portuguese 
-of-war {y^ifW/ii) being thv moKt familiiir member of the 
pi The sub~cla.SK is divi<led into two orders— viz., the 
and the Phytopharida. 
L CALYCOi'ttoKiD.*. — This order includes those 
^kewphora whose hydr^soma it fret and otAxmt, and is pro- 
ftiitiJ fy " «rt*«i*/yfM" attisihed to its proximal end. Tht hydro- 
emtsiits tj ser^rai polypitts, united by an unbranthtd <wm>- 
whiek it high/y Jtanbfe and (onlradiU, and nn'/r devthft a 
mtietdar layer. The prexitnal end of thf hydrosonut m 
intffi a peeuliar cavity eatied the " tamatocyst." The re- 
ergans are in the form af mrdmifyrm gonopheres pr^ 
by tuddingfivm the pedune/es of the polyp ites. 
In all the Calyto^herida the eccnosarc is hiifonn, cylindrical, 
unbfanched, and highly contractile, this last property being due 
lo the presence of abunduit muscular fibres. " The pios,\m3\ 




94 



MANUAL OP ZOOLOGY. 



end of the ooenosarc dilatei a little, and becomes ciliated i: 
Icnully, (bmiing a small chuinher" vrhid) coinmiuiiaiics with 
the iiectocalycine canalik " At its ujiper en<l tliis chamber is 
a little constncted, and so passcn, by n mure oi lexK nancmed 
channel, into a variously-shaped sac, whose walls an; directly 
continuous with its own, and which trill henceforward be temed 
the iiSmaloiyst (tig. iS, 3 b). The cndodenn of this sac is cil- 
iated, and it is generally so immensely vacuolated as almost to 



■ 

ith I 





FIc. il.~-Uaiphota|ar ntfihs Occuiie HH'°>M>- ■' Oincmn of Ac iinwIuBl *>■ 

CahafHr'Hm h NMIoaJyCH: / Vo\i\>\tn: I Tttiaittm. j. Dlunm tt ■ 
C*at^A*nd A tf* PrtxinuJ And dnuL nHUdyi.^ ; / Sonuiocyai : r Cwkhm • 
it H|vr«pbf!liun or brad; ' UfdoMfiirm ^nDpn<frc;^Po]ypfie^ 'PxdArii line* 
it til. I and ] indiriu ihi indndtmi. thi right lln< with ilig cltvqaea iadioca 
■b( ect«ii«ni. (Afin Ituiley.) 

oUiierate the internal cavity, and give the or^n the appeoinnce 
of a cellular mass." — (Huxley.) The polypitcs in the Ca/jw- 
pkorida oAen show a wcll-maikcd division into three portions, 
tcnncd respectively the proximal, median, and di^ial divisions. 
Of dKSC.thc "proximal" dtvlsioit is somewhat contracted, and 
fonns a species of pedunde, which often carries appendages. 
The "median" ponJon is the widest, and may be termed ilie 
"gastric division," as in it the process of <li^e5.tion is carried 
on. It is usually seraraled from the proximal division by a 
ralt'ular inflection of the cndodcmi, which is known as the 
" jiyloric valve." The polypitcs have only one tentacle " de- 
veloped near their basal or proximal ends, and provided with 
lateial branches ending in saccular cavities," and ftimished 
with numerous thread-cells. The proximal ends of the poly 



>oly ■ 



CCELEMTERATA : HYDROZOA. 



9S 



r*. 



, Jtcs usually bear cenain oveilappinff plaws, of a protective 
nature, whkh are tenned " hyOrophyllia," or " bracts." They 
are coni|>osed of prooestes of Ijoth ectoderm and endodenn 
(fig. 18, 3 ■/), and they alu-ays contain a divcrtiailum ftom the 
totDBtic canty, which is caltnt a " phyllocyst." The Cafyco- 
phorida always possess swimnimg-bclls, or " ncctocalyccs," by 
ihe cootraciions of which the hydrosoma is propelled through 
the water (fig. t8, >). The ncctocUyx in .siriictuie is very 
simitar to the "gonocalyx" of a medatiform gonophore, aa 
already described ; but the fomter is devoi<l of the gastric or 
genital sac — the " manubrium" — possessed by the latter. Each 
ncciivaljTt 4:onsi«ts of a bcll-shapcd cup, attached by its base 
to the hydrmoma, and provided with a muscular lining in the 
interior of its cavity, or " ncctosac' There is also always a 
"velum" or "veil," in the form of a membrane attached to 
the mouth of the ncctosac round its entire manin, and leaving 

central aperture. The peduncle by wliicli the rteciocalyx is 
attached to the hydrosoma conveys a ctnal from the somatic 
cavity, which diblcs into a riliulcd chamber, and gives off at 
l«iAt four radiating can;ds, which proceed to the circumference 
of the bell, where they are united by a circular vessel ; the 

tire system constituting what is known as the system of the 

nectocalyctne canals." In the tjpical Caiytvphgrida tno 
occtocalyces only are present, but in some genera there are 
more. In Praya the two nectocatyces are to apjiosed to one 
another that a sort of canal is formed by the union of two 
ves, one of which exists on the side of each nectoralyx. 

is chamber, which is present in a more or less complete 
in all the genera, is icnncd the " hydroccium," and the 

nosaic can be retracted within it for protection. 

The reproductive bodies in the Caiy^iiphoruia are in the 
of inedusiform ^nophores, which are budded from the 
'peduncles of the polypiies, becoming, in many in.itances, de- 
tached to lead an iii<lependent existence. In tome Calyiopho- 
Tida, as in Abyia, " each segment of the coenosarc, provided 
with a polyptle, its tentacle, reproductive organ, and hydro- 
phyllium, as it »c(|iiires a certain size, becomes detached, and 
Icjuls an independent life — the calyx of its reproductive otgait 
serring it as a propulsive apparatus. In this condition it may 
acotiire two or three times the dimensions it had when al- 
tacned, and some of its iiaris may become wonderfully altered 
to fown."* — (Huxley.) To these detached rq)roductive por- 
tions of adult Caljw^rida the term " Uiphyoiobids " has 
applied. 

As regards the dcvelopmcoC 0/ the Caiyeopturidet^ " not 




96 



MANUAL OP ZOOLOGY. 




onl)r the new polypitcs, but the new nectocalyces find repnv 
ductive oi{^x, and even the branches of the tentadet, are 
(tevdojied on the proxinul nde of the old 
ones ; so that the distal appenda^Ecs are the 
oldest."— (Huxley.) The proce« of de- 
velopment is therefore the reverse of what 
obtains among&t the Hydroida, 

Diphya ^fis. 19), which may be tokeit 
as the type of the Caiyafikorida, conKists 
of a delicate filiform coenoarc, provided 
proxiinally with two Urge mitie-diapcd nec- 
localyccs (i', r'), of which one lies entirely 
on the distal side of the other. I'he pointed 
apex of the distal ncctocalyx is received into 
a special tavity in the proximal ncclocalyi. 
ITic "hydrtedum" {h) is formed partially 
by thU chamber in the nectocalyx, and par- 
tially by an arrhcd Kioove prolonged upon 
the inner surface of the distal nectocalyx, 
within which the ccunosarc movw freely up 
and down, and can be entirely retracted if 
ncccssarj". Tlie upper part of iie cacnosarc 
dilates into a aniall ciliated cavity, from 
which are fpven oflT two tubes, which pro- 
ceed respectively to the distal and proximal 
nectocalyccs, where they open into the cen- 
'Ifi^i'Sr^B- OaX chamber from which the ncctocalydne 
oOa^^SiKmha). csnals take their rise. The upper portion 
ry»?7!'i>«tiJ*Sj; of this small ciliated cavity is prolonged 
r'^™wr^^m?Si proximally into the larger chamber of the 
H«ypiicicKhi>tA>u " sonutocysL" The oxDosarc {() beats 
InaudicBtKis. polypites, each of which is protected by a 
ddicate glassy " h]rdroi>hyltium.'' 

DivHioxs 07 Tiia Calycopuorida— (Arru Hwxlev.) 

fom. I. Diffyi*. — Ncclocalycet not moi* Ihin Iwn in number, uid of 
a polvgonnl ifuu HjdroKJDin of Ihe pruiimal ncctocatyx complcle, or 
cIwM potltdoifj. HjraraptnljiK well <ltvcIo|wit. 

Fam. II. SfXffTVHtrtiJa. — Neetocaly^ ptobabiy nut nior# than two In 
niunbcr i llie proKimn] oectocolyx sphnoidM, with » complcle hydnrdiuii. 
No hydrophyllla {?>. 

Fit. III. /Vai-uJ^.— Ncctocalycct Iwo In number; hyclKtda incom* 
(ilctc luitt ijToove-ukc. Polypltct jiiotoctcct hy hyilronhjllln. 

Fam. \\. Hifftfvdidtt. — Nvctoolnttnnnuiwu; nydrcecla incomplete, 
rolypitn not pmiccted by hydrophyllia. 

Oxz>£it JI. PHYSOi'tiORiD.e. — Thls second order of the 




I 






CCELEKTERATA : IIVDROZOA. 



9r 



Hydrous comprises those SifActwpiora m wAUh tht 
Mjf^w»ma antistt sf sevtral foiy^tts unileit {<}■ a fitxt^t, an- 
trattik, tinhramked or very tligMy bra$i{hed aatatare, the /riun- 
nuU txtremily ej whkk is modi^ediiUo a " ^naimat^k^t'' and 
it umttima prcvidtd with " nnltxaiyca." T^ />,^yfdfi have 
rdhtr a tiiigte iam/ ttnhuit, or the tentades arise direaiy from 
tht eemasare. " Hydro^yUia " are mmmaniy frtta^. The re- 
praditetivt Mies are dAthptd u/vn g^noNaslidia. 

The caiwMarc in ihe Physoph^ridir, like that of the Caiyfo- 
fharidtt, is petfeclljr flexible and contrsctile; but it is not 
neccKMuil^ elongated, being sometimes spheroidal or discoidAl. 
The proximal end of the <xenoiarc " expands into a variously- 
shaped enlargk-incnt, whose vails connsi of both ectoderm and 
endodcnn, and which encloses a wide cavity in free commuiii- 
cction wiih tlul of the canosaic, and, ttke it, full of the nuiri- 
live fluid. From the di&tat end, or apex, of this cavity depends 
a S3C, variously shaped, but always with tough, strong, and 
elastic walls, composed of a substance which is slated to be 
limiUr to chitine in composition, and more or less completely 
filled with air." — (Huxley.) The large proximal dilatation of 
the cccnoKtrc is terroed the " [Hieumalophore," whilst the chiti- 
nous air-sac which it contains is termed the " pneiimatocyst " 
(fix. 18, i)v The pneumatocyst is held in position by the 
rcflectioa of the cndodcrm of the pncumatophorc over it, and 
it doubtless acts as a buoy or "float" In the Portuguese 
man-of-war (Pkjtalia) the pneiimatocyst communicates with 
the cxtenur by means of an apenure in the ectoderm of die 
poeiimatophore. tn Vddla and Porpita the jineiimatocyst 
communioues with the exterior b^ means of several openings 
called "stigmaU;'' and from its distal surface depend numerous 
slender processes, containing air, and known as "pneumatic 
filaments." 

Tlie potypites of the Physopharida resemble those of the 
CaJyeopharidie in shape, but the tentacles have 3 mucli mure 
oompltcated structure, and are sometimes many inches in length, 
as in PhysaJia. The " hydrophyOia " have essentially the same 
structure as llwae of the fomicr order. There occur alw in 
the PhytofharidazKtiMTi jieailiat bodies, termed " hydrocj-sts" 
or " feelers " (" fuhlet" and " taster" of the Germans). These 
resemble immature poly|>itcs in slinpe. consisting of a pro- 
longation of both ectoderm and endodcrm. usually with a 
testadc, and containing a divcnicuhim of the somatic cavity, 
the distal extremity being closed, and furnished with ouincious 
lai^ thread-cells. The}- are looked upon as " organs of pre- 





98 



MANUAL OF ZOOLOGY. 



3tt^^ 



hension and touch," nnd they are somewhat analogous to 
" itemalophorcs " of some of me Strtulariiia. 

As Tcgaida the rcpioductivc organs, thc>' arc developed upon 
special procesacs or " gonoblastidia," and tlicy may remain 
permnnenrly attached, or they may be thrown on as free- 
svrimminK meduKoids. In many of the PhytopAorida the 
male anil remale goaopbores differ from one onoiher in form 
and siif, and they are (hen termed respectively "andro- 
phorcs" and " gynophores." As regards their development, 
the J*Apof/urida obey the some general law as the CaJy- 
<cpheriila. 

In Pkysophora the hydrosoma consists of a filifonn coenosare, 
which bears the polypiles and their appcndai;e3, and dilates 
l>rDximully into a pncumatophore. Below this point the 
ccenown: bean a double row of nectocnlyces, which are 
channelled on their inner faces to allow of their attachment 
to the cocnoiarc. Th<rre are nu hydrophytlia, but there is 
a scries of "hydiocysu" on the proximal side of the poly- 
pilcs- 

PAytttlia, or the Pomigiicsc man-of-war (fig. lo, n), is com- 
posed of a large, bladder-like, fuiiform "ftoai" or pncumato- 
phore — Kwneiimes from eight to nine inches in length— upon 
the under stirfaoe of which are armnged a number of potypiies, 
together with highly contractile tentacles of great length, " hy- 
drocysts," and rqirodiictive organs. Physalia is of common 
occurrence, floating at the surface of tropical seas ; and deets 
of it arc not uncommonly driven upon our own shores. 

In Vrteila (fig. ao, i) the hydrosoma consiitt of a widely- 
expatided pneumatoi>liore of a rhomboidal ihape, carryiDg" 
upon its upper vtirCicc a dia^nal vertical crest. Both the^ 
horizontal disc and the vertical c-rest are composed of a soft 
mar;ginal "limb," and a central more consistent "firm part" 
" 1*0 the distal surface of the firm p,irt of the disc are attached 
the sc\'cral append^es, includiT^, i, a single Urge polypite, 
nearly central in position; a. numerous smalt gonobbMidit 
which rcKmble polypitcs, and are termed "phyogemmoda; 
and, 3. the reproductive bodies to which thete laxt give risa 
lite tentacles are attached, quite independently of the poly^ 
pites, in a single series along the line n*hcre the l^rm part and 
limb of the disc unite. There arc no hydrocysts, ncciocalyces, 
or hvdroiihvllia. . . . On all sides the limb is traversed 
'ng systctn of canals, which are ciliated, and 
the cavities of the phvogcmmaria and large 
-(Greene.) VrUlla is about two inches in 
s half in height. It is of a beautiful blue 



I 




CCELENTEKATA ; HYDROr^A. 



99 



colour and scmilnnsparcnt. and it floats at the surface of the 
tu, with its vcnicai crest exposed to the wind us a »ail. 




, to-^Pkfff^ni^. * Pondtu**« mMft-rj(-wu trtfmJi* »r^v/wrlthQwinc the 
•Hmn tW tad iIh polyfittt lad Icalack* (lAu Uuky}: i frii/lm nJt^rU 



I>ivinoin or tnx PnrwnioKiiwic.— (ArrcR Huxlkt.) 



t/im. 



L /f^MtomlMCr.— Ilydrecoma with ncctocalycci &nil h}\lropli]>lli*i 

luUr Wtlud wU Ibc other otEMU into troops which are amn)^ U 

ihla ialtmb •tang lh< ccaiouuc. Cccuomk lilifonn- Pncuma- 

>a 

)m. II. A7V*fliimm»/r.~HjJfo*ijma wiih ncctucatjvci wid hjrdro- 
lUk^ Ihe Utter Hnased with ihe otltei orguu in ■ oontinuooi terici. 
c MUonn. pMWiurlomt tnall. 

III. / ! t r« i]M« n' « rf j.— Hydfownw with ntctoCTlvctt, but without 
iJUUl cad of Ibe lUifonn ctoMum clUueiL Pneomatocyd 

IV. A A nytkU. -~ Hydrowma without nrcl(xalyc«i, bol with 
7Dta. PiHanMacjrti occupying alMaet Uk whole ot the glabatu 

.V. KU ttftl f oada. — Uyims/sai» wiAoat eilhor occtocaltctt « 



100 MANUAL OF ZOOLOGY. 

Fam. VL Fhytaliada. — Fneamatocyit occapving nimott the whek cf 
t)ie thick and irrcguUrlf fu^form coeaomrc No nectocaljcei or hTdto- 
pbyllia. 

Fata. VIL Vtltllidir.—HyATiysoitD^ without nectocklrces or hjdm^jV 
lia ; with short, simple, or branched lubmaiginal tenUdes. A iiD{rIe 
central principal potypite. Pneumalocyst flattened, divided into chambeit 
b^ numerous concentric partitions, and occupying almost the wbok of the 
discoidal canosarc 



CHAPTER X. 
DISCOPHORA. 



Sub-class III. Discophora (Aealefha* in part). — Since this 
sub-class contains only a single order, that of the Medtmda, a 
single definition necessarily suffices for Jjoth. The Medimda 
are defined as "Hydrozoa whose hydrssoma is free and oceanie, 
eonsisting of a single nedomlyx, from the roof of which a sing^ 
polypite is suspended. The nectocaiyx is furnished with a system 
of canals. The reproductive organs are as processes either of the 
sides of the polypite or of the nectoeeUycine canals" — (Greene.) 

The Medusidx comprise most of the organisms commonly 
known as Jelly-fishes or Sea-nettles, the last name being de- 
rived from the property which some of them possess of severely 
stinging the hand, this power being due to the presence of 
numerous thread-cells. As employed by modem naturalists, 
the order is very much restricted, and it is by no means impro- 
bable that it will ultimately be entirely done away with, very 
many of its members having been shown to be really the fi^ 
generative buds of other Hydrosoa. As used here, it corre- 
sponds to part of the Gymnophthalmate Medusa of Professor 
£. Forbes, the Sleganopliihalmate Medusa of the same author 
being now placed in the sub-class Lucemarida. 

The hydrosoma of one of the Discophora ( = a Gymnoph- 
thalmate Medusa) is composed of a single gelatinous bell-shaped 

* The old sub-class of the Acalepka contained the Gymnophtlialmatt 
Mtdusa (=; the Discofhara,) and the StrgaHophtkalmaie Mtdiaa (•■ the 
Lucernanda in part), the two being placed in a single order under (he 
name oi Fulmograda. The Aialepha also contained the Clenopkem and 
the Calycopkor^da and Physophorids, of which the (ormer constituted the 
order Ciliagrada, whilst the Iwo latter made up the order Pkyiograda. 
The Ctenophora, however, are now generally placed amongst the AcHnmua, 
n-hilsi the Cafyiaphorida and Fhysophorida conjiiiule the Hydnuoal anb- 
diss SipAffn^kara. 




CCBLENTERATA : HYDROZOA. 



101 



swiTnming organ, the " ncctocalyx" or " disc," from the rocrf of 
which a single polypitc is suspetide<i <lig. ii). Tlie interior of 
the ncctocalyx b often called the " nectoaac," and the term 
^*< codonostoDu " has l>eeD propoMtl lo detigoaie the open 

^^K Vfc. >i:—Mc(>lHl(i(y tl Hiiaidm. <• A Mfdiiiid { TttaumnvtiMi utn in sroAlc, 
^^V A m rii^ 1A4 cfnlru wiypixt^ Otv ruAUUii^ and cLixulit CT>iiocuZyclii« uniOv (ha 
[^^ VUfiuJ wkkn mtti (cnuclei, «kJ (hv nprutuciivc qiyvhi ; i The utn« vie*fd 
tn^ bitow. 'I\a d«i«l l^u* indiuist tin nurgui nf iha tvlom- 




01 U 
^nd. 



noath of the bclL The mar^n of the nectocalyx is produced 
inwards to fomi a si)ecio of shelf, running round the nurgin 
of the mouth of the bell, and termed the " veil " or velum," 
the presence of which the nectocalyx is distinguished from 
le somcu'hal similar " umbrella " of the Ltntrnarida. The 
odcTmal lining of the central polypitc or " manubrium " 
(sometimes called the "proboscis") is prolonged into four 
ladiaiing anab, which run to the periphery of the nectocalyx, 
where ihey oie connected by a circular canal which runs round 
its circumference, t)ie whole constituting (he nTitcm of the 
" ncctocalycinc cjmals " (formerly called the " chylntjucous 
cuuds"). From the tiTcumfcrcncc of the ncctocjilyx depend 
Duiginal tentacles, which are usually hollow processes, com- 
posed of both cciodcrtn and endodenn, and in immediate 
coonection with the canal system. Also round the circum- 
femtcc of the nectocalyx are disposed certain " marj;:iual 
bodies," of which two kinds may lie distJn^uiithed Of thete 
the first are termed "vesicles," and consist of rounded luicx 
lined by epithelikim, and containing one or more solid, motion- 
leu coiKTetions — apparently of carbonate of lime — immersed 
in a transparent Hum. 'ITic second class of mar^nal bodieS) 
Taiiously termed " pigment-spots," "cye^pccks," or "ocelli," 
consists of little aggregations of pigment enclosed in distinct 
tarilies. Tlic " vesicles" arc probably rudinicnlai)- organs of 
beahng, uk) possibly the eye-specks are a rvdiinentar)' form of 
T^ial appaiatus. The oral maigia of the polypitc may be 




102 



MANUAL OF EOOLOGV. 



simpk, or it may be produced into lobes, which are most^ 
frequently four in sumbcr. The CBScntial elements of geneni' 
lion are pro<1uced in simple expansions cither of the wall of J 
the manubnum or of the radiating nectocalycine csnab. 




RB' Ml— Ctbb of ukeJ-*!*! JTrAv. A S*rtU frmwr ffi m. wM tdina l d* 
•rMDcJViMi ay Mat of thtnoinl uilnilii (afler Gtwh): B MtditrU^iima* ' 

From the above description it will be evident that the 
Mtdusa is in all essential respectx identical in Mructure with 
the free-swimming generative bud or gonophore of many of 
the fixed and oceanic IMroUKi. Indt-cd, a grot many forms 
which were pR'viously included in the Mfduiida have now 
been proved to be really of this nature, and it may fairly be 
doubled if this will not ultimately be found to apply to aU. 
A> to the value, however, of the order MeJuiiiia, the present 
Uate of oiir knowledge ix well expreitsed by the following oon- 
chttions which have been drawn up by Professor Greene i— 

"i. That several of the organisms formcity described as 
Medmida are the free gonophoret of odier orders of HyAvaoa. 

" a. That the homology of these free gonophoics with those 
simple expansions of the body-wall which in J/ydra and some 
other genera are known to be reproductive organs by their 
contents alone, is proved alike l>y tite existence of numerous 
transitional forms and by an app^ to the phenomena of their 
dereJopjncnt. 



A 



CCBLENTERATA : HVDROZOA. 



m 



" 3- That many of the so-called MeJusiJa may, from ana- 
logy, be- rt-gardccl as, in hkc manner, mediuifonn gonophorea. 

" 4. Hut that ih<:re may cnUi, iievertheless, a group of 
Mniuiid forms which may ^wn rvse by tnie rqvodtiction to 
organisms directly membling their parents, and therefore 
ironh^ of being placed in a leijaratc order under the name 

1'he tame authority roncludett by nenurlting thai to the 
order as alwve de5n«I "may be referred proviGtonatly that 
large assemblage of forms anatomically similar to true MeJu- 
sida-, but whose development is unknown," Besides the la^ 
group of forms thus temporarily admitted, all the DratJtyntmidit 
and ^gmiiitt are staled by (legcnbaiier to fulfil the conditions 
oi the above definition, and aliould, therefore, be looked upon 
as true Medusida. 

As 10 th« development of these true Moiutida, little is 
known for certain. It api>car5, hi>wcvirr. that in Trachynrma, 
^Xiiwfisis, and other genera, the embryo is directly developed 
into a form rrsembling its parent, niihout passing through any 
tBtermcdiate changes of form. It is hardly necessary to re- 
mark that this is not the caxevrith the embryos of a medusifom 
gonophore, ihrM.- ticing dcvi.'lii|>ed into the sexless Hydrvxoen 
by which the me^luwitl was produced. 

Id tb» connection, allusion may be made to the long-known 
hex that certain medusiform gonophore« art c.ipable of pro- 
ducing indc|>cndent forms directly resembling themselves, but 
this is by a process of gemmation, and not by one of true re- 
production. Technically these are called *' tritozooidi," as 
being derived from organiKms which are themselves but the 
fencrativG lobids of another being. This lingular phenomenon 
Mu been oteen'ed in various medusiform gonophores (c.^., 
Sartia gtmmi/fra, Ag. 32, a), the buds springing in different 
species from the gonoc.itycine canaU, from the tentacles, or 
bora the sides of the polypitc or manubrium. 
Hn^e '' naked-eyed ' Meduia, though mostly very diminutive 
^P point rif size, arc exceedingly clcsaiit and attractive when 
^bmined in a living condition, resembling little bells of traux- 
^tcnt glau, adotned here and tliere with the moM brilliant 
colours. 'I'hey ocnnr in their pro]>er lo<'alitie)i aii<i at proper 
iriintii in the roost cnormoiu numbers. 'I'hey arc mostly 
photphorescent, or capable of giving out light at night, and 
ibey appear to be one of the principal sources of the lumi- 
noaty of the sea. It does not seem, however, that they phoB- 
phorcsce, unless initated or excited in some manner. 



I 



104 MANUAL OK ZOOLOGY. 

CHAPTER XI. 

LUCERNARIDA AND GRAPTOUTID^. 

SUXLASS IV. LUCKK.VAR1DA {AtaJepha, ui part).— The mem- 
bers of (his sutxbss may lie defined as Hydroioa " whou My- 
drosoma hat itt bast datdepcd inlo an ' umhrdlal in ihe toaJls tf 
u-kkh the rtpr^Hdive organs art produitd." — (Greene.) 

A large number of forms included in the Luamariita were 
described by Edward Forbes under the name of SIfganofAlhai- 
mate Medusa, being in many external characters closely similar 
to the AfeJutufa. 'Hicse " hidden-eyed " Maiune arc fumiliar 
to every one as " sea-blubbers " or " sea-jellies," and they 
occur in great numbers round our <^i>asls during the summer 
months. The resemblance to the little jclly-li*hcs is especially 
Strong between the disc or "ncctocniyx" of the tntc Aftdusidet 
and the " umbrella " of the Luitrnarida, the Jailer being often 
a bell-shaped swimming organ, with niarginid tentacles, and 
containing one or more polypitcs. These analogous stmctoics 
(figs. 33 and 15) are, liourever, distinguished as follows^— 
I. The "umbrella" of the tttetrnarida is never furnished with 
a " velum," as is the ncctocalyx of the Medusidte. 3. The 
radiating canals in the former arc never less than eight i 
number, and they send off numerous anastomosing bmnches^' 
which join to form an inuicale network ; whereas in the lattc~ 
they are rarely more than four in number, and though the; 
may subdivide, they do not anastomose. 3, In the place 
th« separate and unprotected "vesiclei" and "ocelli" of th 
iitdmida, the marginal bodies of the iMeemarida consist 
these bodies combiaed together into single organs, whidi are 
termed " lithocysts," and which are protected externally by a 
sort of hood. 

The Ltttemarida admit of being divided into three orders 
— vie., the Lumnariads, the Pelagida, and the Rkixoitomi^t. 

Order 1. Luc£RNARiAt>^ — This order includes those Zttar- 
narida wAuA have mdy a single fidypiie, are fixed by a proximal 
kydrvrhiu, and postett short tentae/es dn tie margin of the vHh^ 
brtUa, Tht reproductive eiemevts ■' are iietYh<ped in fke primitiz'^^ 
hydrosmna witAovt the inters-etitien of fret Sivids." — (Greene.) ^^ 

In Luctraaria (hg. 33), which may be taken as the ty]>c of 
Ihc order, the body it campanulate or cup-shaped, and is 
attached proximally at its smaller extremity by a hydrorhiia, 
which, however, like that of the Hydra, is not permanently 
Jfxed. IVIien deUched, the animal b able to swim with toUt- 





oelenterata: iivdrozoa. 



los 



rajndily by means or the alternate contraction and ex])an> 
sion uf the umbrella. Around the margin of the umbrella are 
tufts of slion tentacular processes, and in ica centre is u pnljr- 
ipite friih a quadrangular, fout-lobed 
louth. " In Iranivene section the 
;Hie may be described as .^oine- 
quadrilitentl, with a sinuous out- 
hich expands at its four angles 
form as tn:iny deep longituduial 
Ids, within which the simple genen- 
ive bands an lodged." — (Greene:) 
~ »de longitudinal canala are formed ' 
by septa paiaing from the walls of the 
lypite [o the inner surface of the Qun, 
id a circuUr canal nms immediately 
eath the insertion of the tentacles. 
<e rc{>roductivc ckmenis arc pro- 
dt*ocd within the body of Lu^traarh 
ilwl^ without the intervention of any 
neralive tooid. 

Okdi'-k II, I'klacii>«. — This order 
dcfinnl as including I.tuftnarkla 
'huh foftni a lingif poiypitt oii/y, and 
an umhtlia with marginal ttnUultt. 
TSc rtproJuetiit elrmenti ** art lUv^^td 
iH a /tet umbnlla, wkieh lither tofttii- 
hila llu pnmUh^ kydrotoma, or u firo- 
duad byfiaim from an attaeheJ Luar- 
nanii/."— <Greene. ) 

TVo types therefore, exist in the Pflagii/a. The one t)'pc 
is represented by a 6xed " tiophosome," resembling Luimtaria, 
but disiinguishcd from it by the &ci that the generative ele- 
ments arc not developed in the primitive hydiosoma, but in a 
free "gonosome," which is ]iroduced for t)ie purpose. The 
" 1yj>e, represented by Pdagia itself, is permanently free, 
^crebv differii^ from Liatrfiarui, which it ap))run<-hi.'s. on the 
Other Hand, in the foci that its generative elements arc pro- 
duced in its own umbrella without the intervention of free 
generative zodid^ Ptlagia, ho«'c%'cr, dilTcrs considerably la 
Structure from La<tmariii, and in all essential characters is not 
Mltttomically separable from a Sttgatufhthaimatr Medmid. The 
IHoecss of reproduction as displayed in the 6rst section of the 
Pdapda will be considered when treating of that of the Jifii- 
aaivmida, there being no tmj>ortint difference between the 
two, except as concerns tJio structure of the generative zootds. 



Dy! 

"d«~ 
ill 




trntatv «knVia£d nUfhfd 

JuLniloji}. 



io6 



MANUAL OF ZOOIXJCY. 



Obdcr in. RhI20!;tomii>£. — The members of thb order 
arc defined ax lieini^ jMetrnarida, in whi4:h the refrwtudive 
dements are deveiofea in frtt witit, prcJvad by fiuiffafrem at- 
talked I.tuernaroidt. Tlu umbrdla sf the genfriilit>f tairids is 
•wilknut mtrgina/ tentatUt, and the f^yfilts arf " numtreus, 
nwdified.ferming vitA the gmilstlia tt daidn/ffrin ituus dtptnding 
from Ike ww^rrfifii.''— (Greene.) 

The following b a tmef Munmair of ihe life-historr of a 
inanbei of ihU exiniontinary oider (fig. 14), the illustntion, 
htiwever, repre*enting the development of Chrysaera, one of the 
Pda^da, in whicJi the |)henomni3 nrc cwenlially the same; The 

nbr)'o is a. frcc-swimming, oblong, ciliated body, termed n 
_^ptaiiula"(ii), of A very minute si K, and composed of an outer 
'nnd inner Inyer enclosing a central cavity. 'I'he pUnula soon 
becomes pear-shaped, and a depression is formed ai its larger 
end. " Next, the narrower end attaches itself to some sub- 
marine body, whiUt the depreiuian at the opposite extremity, 
becoming deeper and <leeper, at length communicates with the 
interior cavity. I'hus, a mouth is formed, around which may 
be seen four smoJl protubeT.incc3, the rudiments of tcntacuUi. 
In the interspaces of these four new tentacles arise ; others in 
quid: succestjoa rpake their appearance, until a circlet of nu- 
merous lilifonn appendages, containinf; thread-cells, surrounds 
the distal inarftin of the ' Hy<lTa-tiiba ' (i), as the young organ- 
ism at clii.i stage of its career has been termed by Sir J. G. 
DalyeU. Tlie mouth, in the mean time, from being a mere 
quadrilateral orifice, grows and lengthens itself so ax to consti- 
tute a tnie polypitc, occupying the axis of the inverted iimbreUa 
or disc, which supports the marginal tentacles. 'I'he space 
between Ihc walls of the polypitc and umbrrlb is divided into 
longitudinal canals, whose relations to the rest of the organisiQ, 
and, indeed, the whole structure of Hydra-tuba, closely re- 
semble what may be seen in Luamaria." — (llrecue, Mvmai 
ef Ctrlm/frata.) 'Hie Jfydra-tttta thus c^mstilutes the fixed 
" Luceniaroid,' or the " trophotiome " of one of the /tJUaitf- 
mida. In height it is leas than half an inch, but it posMssea 
the power of forming, by gemmation, brgc colonies which may 
remain in this condition for years, the organism itself being 
incapable of producing the essential elements of generatiotL 
Under certain circumstances, howe%-er, reproductive xooids are 
produced by the following singular process (Ag. 14). The 
/fydra-tuta becomes elongated, and becomes marked by a •«• 
rice of grooves or circular indenutions, extending tnnsvenely 
across tne body from a little below the tentacles to a little above 
/Ae tfxed extremity. At this 6ta^ the otg^ism was described 



I 




CCELENTERATA : HVDROZOA. 



107 



as new by Sara, tinder ibe name " SrypAufwui " (A. The 
aniiuUti»nt or comuicttons go on deepening;, ana. become 
lobcd at their margin, till the Sty/^Aisfi'ma lUMiimc^ the a!(|>ect 
oTa pile of sauccit, arranged one iijion snothL-r wiih thdr coti- 




t of LuMn*iUi (C4>yMiuv> ^ aiiat*dcaitirTO0F''j>l«iu)>;'' 



TBrdaoita:' ,. , , ,. _ . 

bi ahldi ■ (mk ortki c< UnUcLs t« be™ diTiluiirO Dru du Ikm : / Fi«e> 
tHnmtmit^ mtivatii h " Kptiyrx" pcodiKcd by £»■>& IroQ the Itydn-lubL 






ave surfaces upwards. This stage was described by S»i5 
nnder the nunc of " Strobih " {if). The lentacular fringe which 
origiDally suTRHinded t}ie margin of the Hydra-luba now dis- 
Bppcan, and a new circlet ix developed belovr the umulution.t, 
ai a point a litllc above the fixed cxlremity of ihe Strati/a (A 
"The disc-like xegmenU above the tcnUclcs gtiMlunlly fall off, 
tad, swinuning freely by the contractions of the lobcd margin 
whidl cadi presents, they have been described by E^chstholiE 
B tree M^usida under the name of Efhyra" (/), Each 
Ephyra, however, soon sliows its true nature by becoming 
derelopcd into a free-svnmining reproductive body, usually of 
Luge aize, witli umbreEb, hooded lithocysts and tentacles, 
constituting, in ^t, a Slf^ancpkthiilnuile Mediita. The re- 
productire Mwid now $n-imx freely b^ ibe contractions of its 
umbrella, and it eats voraciously and incrcasct largely in size. 
The cascntial elements uf generation aie then developed in 
ndal antics in the umbrella, and the fertilised ova, when 
liliciated, appear as frcc-swinuning, ciliated " planuljc," which 
lit iheniHclves, become ffydra-tulKe, and commence again Ihe 
qrde of phenomena which we have above described. 

A* rafpudx thcMsrof theie reproductive zouids as compared 
with the oiganism by which they are given olT, it may be mcn- 
tioacd thjU the umbrcU-i of Cjntua anlua has been found in 



lOS 



MANUAL OF ZOOLOGY, 



■ 

norcH 
kh it ^ 



one specimen lo be seven feet in diameter, with tentacles 
than thy fecc in leni;t)i, the fixed Zwemartiid from whkh 

U-3H produced not being 
more tlun hair on inch in 
height. 

As regards the special 
structure of these gigantic 
reproducti'i-e ' bodies, con- 
Biderabic diETcrenccs obtain 
between tlie RkiteilomiJa 
and that section of the 
PttagiJa in whidi this 
nietliod of rc|iroductton b 
employed- InxhK Pe/t^dtt, 
nxmvXy, the geneintive 
looids possess a general, 
though chiefly mimetic, re- 
sembUmce both to the 
genuine Disee^ara and to 
the frecfwimining medusi- 
fofin gonophores of id 
many of the Hydrotoa. and 
they have the folloimg 
structure. Each (fig. 35} 
Ccncncnc consists of a bell-shaped, 
gelatinous disc, the "urn* 
brella," from the roof of 
which is siisiiended a hi]ge jiolypite, the lips of which are ex- 
tended into lobed processes often of oonsiderable length, " the 
folds of which serve as tempomry receptacles for the ova in 
the earlier stipes of their development." The poly]>it^— 
manubrium or proboscis — is hollowed into n digestive sac, 
which communicates with a cavity in the roof of the umbrella, 
from which arise a series of radiating canals, the so-called 
"chyIa(|tieous canals." These canals, which arc never less 
than ^ht in number, brandi freely and anastomose as they 
jnas tcm-ards the )>eTiphery ol the umbrella, where the entire 
iteries is oonnccteid hy a circular marginal canal. Tliis, in 
turn, sends lub\ihu' processes into the marginal teiitac:les, which 
are often of great length. Besides the tentacles, the margin of 
the umbrella is fiimishcd with a scries of peailiar bodies, 
termed " lithocysts," each of which is protected by a sort of 
process or hood derived from the ectoderm, and coDUsia 
essentially of a combined "vesicle" and " pigment -spot," such 
as have hvsa deacribed as occurrinj^ in the MedHsUa. lliese 




I 



K(Ud it one of thi I'lUtUM ifiArytam 



i^WMECoI >A« C«(Wi 




nuunnal bodies likcwUe communicate with the chylaqucous 
ouw The rqiroductive elements "aic lodged in saccular 
processes of the lower poritoa of the central cavity, iromedi- 




ft bvttt^ H "SHflktio^Mdiq," c^vvivd niLh iIa^-aU iuiUcIo and niiiulc fN>}}^«ftj 

stelf ahove the bases of (he radiating cansls, aiid, being 
usually of some bright colour, form a conspicuous croH shining 
through (he thickness of the di5e."^(Grcene.^ 

tn the Rhiu<itemida the reproductive lootds (Ag. 36) differ 
(iam those wc have just described as occurring in the fint 
MCtioQ of the Ptlngija, in not possessing tentacles on the 
DMi^gin of t)te umtwetia, and in having (he simple central 
polj^tc replaced by 3 conijiosite dendrifonn process, which 
bcar^ numerous |inly])ites, projects far below the umbrella, 
and is thus dcsrribeti by Prafe!'M>r Huxley:— "In the Rhiio- 
stamida (lig. 16) a complex, tree-like miuw, whoKC branches, (he 
' ttooiatodendra.' end in, and are coverird by. minute polypitcs, 
interspersed with clavatc tcntacula, is suspended fiom the middle 
of the umbrella in a very singular way. I'hc main minks of the 
dejicndent polypiferoua ircc. in fact, unite above into a thick, 
fiat, quadrate diitc. the ' syndcndrium,' which is sunpended by 
four stout pillars, the ' <S^6Tosty]a,' one springing from t»^ 



ItO . MANUAL OF ZOOLOGV. 

angle, to four coiresponding points on the under siir&ce oTthe 
umbrella, equidistant from its centre. Under the middle ot the 
umbrella, therefore, is a chamber, whose floor is formed by the 
quadrate disc, whilst its roof is constituted by the under will of 
the central cavity of the umbrella, and its sides are open. The 
reproductive elements are developed within radiating folded 
diverticula of the roof of this geni^ cavity." 

It appears, finally, that amongst the old Fulmograde Aca- 
lephae, or amongst what would commonly be called Jelly-fishes, 
we have the following distinct sets of beings, which resemble 
each other more or less closely in appearance, >but differ in 
their true nature : — 

1. Free meduaiform gonophores of various CorynUa, Seriu- 
larida, Campanuiaruia, and the Oceanic Hydrotoa. 

2. True Medusida, entirely resembling the former in anato- 
mical structure, but differing in the fact that their ova do 
not give rise to a fixed zooid, but to free-swimming oi^d- 
isms exactly like the parent hydrosoma (Trachynemida and 
j£gini(ia). 

3. Hydrozoa, which are provided with an "umbrella" (with 
all the peculiarities belonging to this structure), but which re- 
produce themselves without the intervention of free generative 
zooids produced by fission {Peiagia). 

4. The free generative zooids of most of the Pdagida, with 
an umbrella and a single polypite, the primitive hydrosoma 
being fixed and sexless {Aureiia, Cyanea, &a) 

5. The free generative zooids of the Rhizostomida, with an 
umbrella and a complex central tree bearing many polypites 
{Rhizestoma, Cephea, &c.) 

Of these five classes of organisms, Nos. i and 3 constitute 
the Gymnophthalmate M^usa of Professor E, Forbes, whilst 
Nos. 3, 4, and 5 are the Sceganophthalmate Medusa of the 
same naturalist. 

Sub-class V. Graptolitid«. — The organisms included at 
present under this head are all extinct, and they are in many 
respects so dissimilar, and their structure is so fax from being 
entirely understood, that it is doubtful if any definition can 
be framed which will include ail the supposed members of the 
family. The following definition, however, will include all the 
most typical Graptolites : — 

Hydrosoma compound, occasionally branched, consisting of 
numerous polypites united by a ccenosarc; the latter bong 
enclosed in a strong tubular pyolypary, whilst the former were 
protected by hydrothecie. In the great majority of Graptolites 
the h/drosoma was certainly unattached; but in some aberraDl 



^m&t— da 



CCELENTEBATA ; BYDROZOA. 



Ill 



doubtfullv belonging to th« Kub-clasa — there U retuon 
to believe that ihe hyclrosoma was fixc*l. The polypites wc 
never separated from the cccnosirc by any partition. In numy 
cases the h>'drosoma was strengthened by a solid chitinous rod, 
the " solid UU&," somewhat analogous to the chitinous rod re- 
cently described by Professor Allman in the singular Poty^oon, 
/tAaUefletira. 

From the ubore delinition, it will be seen that the nearest 
living allies to the GraptoJilcs are the Sertularians. In ]X>int 
of fact, if wc do not insist u|>on the prcscnre of a "solid axis" 
as pan of the definition, the Graplolitcs difTer from the Ser- 
tuUrians in tto essential point, save that the hydrosoma is 
always attached in the latter, and was certainly ftce in the 
moot typical examples of tlic former. Indeed, certain forms 
at preieni placed among the Grapteliles — such as Ptilograpsut 
and Dendrografitts — are so simihr to siome living Sertularians, 
that it might l)e well to remove them alto^^cther from the 
GraftfcJitida, and to regard them as extinct representatives of 
the Strtularida. 
^^Aa regards the ralue of the " solid axis " as an element in 
^■^■ng Graplolites, we fear that much stress cannot be bid 
v^n its presence or absence. It is true that it is pre^nt 
in all the most chanicterMic members of the lub-claia, but 
it seems to be <rertainly absent in nome — f.g., in X/tiif/Uft 
Geinitsiinus. -ind in alt species of HattriUs — and there do 
not seem lo be siillicient grounds for excluding these from 
the GraptciitiJa on this account alonc; 

Taking such a simple Graptolite as G. sagittariui (fig, 17, i) 
as the ty]>e of the subclass, the hydrosoma is found lo consist 
of the " solid axis," the " common canal," and the " cellules." 
thK cnlirc polypary is comeou.i and flexible, and tlie solid 
§m is a cylindrical fibrous rod, which gives supjinrt to the 
entire org.inism, and \% oflen prolonged beyond one or both 
ends of the hyilrosoma. The common canal is a tube which 
enckaes the cccnosarc, and gives origin to a series of cellules, 
dtCM being little cups corresponding to "hydrothccie," and 
cndowog the polypiics. Not only arc the csicniial details of 
the Btnicture — with the exception of the solid axis — strictly 
coiDponble with ilui of a SertulaHai\, but tliere is a good 
evidence, ss shown l>y Hall an<I the author, lliat the reproduc- 
ttre process was aUo c.imed on in a manner similar to what 
ve have seen in the other H^dreida — namely, by genemtive 
buda or gonopbores. 

No Grafilatite. however, has hitheno been certainly proved 
to have been fixed by a " b^vlrorhiia," and it is oi\\y '\n 




112 



MANUAL OF ZOOLOGY. 



certain aberrant fonns that 




Fie- aTr— MorphDlDgrof Gntptolitca. 
1. Porliort d{ Crafitali/ej safittat^ 
<W enlarged; d Soliduiii: iCom- 
moo ajial j c Cellulu. 1. Hon- 
oprionidUm GnpIoJiIe (G. argtit- 
U*i4\ 3. Dipnonidian Gnptoliie 

IDiflttrafiMs friilii, rarietjr with 
Qog baul sptoei^ 



there are any traces of a " hydio- 
caulus." 

Besides the simple fonns of 
Graptolites with a row of cellules 
on one side (monopiionidian) (fi^ 
37, 3,) there are others with a 
row of cellules on each side (dip- 
rionidian) (fig. 27, 3}. Many other 
curious modifications are known; 
but there is only another peculi- 
arity which is worthy of notice 
here. This is the occurrence in 
several genera of a basal cor- 
neous disc or cup, which is pro- 
bably the homol(^e of the "float " 
or " pneumatophore " of the Physo- 
phorids. {For distribution of Gr^ 
tolites see Distribution of Hydio- 
zoa in Time,} 

As regards their mode of oc* 
currence, Graptolites are usually 
found as glistening, pyritous im- 
pressions, with a silvery lustre. In 
some cases, however, they arc found 
in relief 



CHAPTER XII. 



DISTRIBUTION OF THE HYDROZOA. 

I. Distribution of Hvbrozoa im Space. — The genera rf 
Hyirosoa have a wide distribution, the mode of reproduction 
amongst the fixed forms being such as to insure their extension 
over considerable areas. The various species of Hydra are of 
common occurrence in the fresh waters of Europe. Cordyh- 
fhora, the sole remaining fresh-water genus, has not been 
found to occur out of the north temperate zone. All the 
other Hydrezoa, without a known exception, are marine in 
their habits. The fixed forms — viz., the Corynida, Sertularida, 
and Campanularida — are represented more or less abundantly 
in almost all seas, extending from the littoral zone to con- 
siderable depths. The oceanic Hydrotoa, Caiycepluirida and 




CCELENTERATA : HYDROZOA. 

Phys0ph«rid«, arc chidiy chnricteristk of tropical seas ; but 
they are found also in die Mediierrancan, and even in sesw not 
i»i from, or even within, tlic Arctic circle. 

II. DisritiBix-noN OK HvDRozoA inTime. — With tlic cxcci>. 
tion of the tmpresston of a Mtdma said to have been observed 
by Professor AgiMix in the fine-grained liilw^aphic slale of 
Solenhofen (Oolite), there are no fossil remains which would 
be tmivCTsalK conceded to be of a HyJnnMl nature. The 
OUhamia of the Cambrian rocks of Ireland hai. indeed, 
been regarded as belonging to the Nytbvtpa ; Init it is believed 
by Mr Salter to be really a {)Jant. It con»u.Ui uf a main 
Mem with numerous secondary branchot, S|)ringing from the 
axit in Kn umbellate manner, but exhibiting no traces of 
hj-drothecae. 

I'hc occurrence of Corynida in a fosal condition can hardly 
be said to be free from doubt. Remains prob^ly referable to 
this order have been, however, recently ducovaed in the Pal- 
xocoic RocluL 'ITic oldest of these was deicribed by the 
author sotne vcant ago from the Lower Silurian rocki of Oum- 
friesahire under the name of Cvryno^ts. More lately a fonn 
called Pa/moevryne has been described from the Carboniferous 
rocks of Scotland. 

The Serfu/arida and Campanulariila sre aotccRainly known 
to occur in a fossil condibon. The fossils called Dmdrvgrafnu, 
CaUegrapsut, miegrafitut, and Oidyotttma. all ai pea^ fdaced 
amongst the GraptoIUes, lue, however, not mpakttVtf mtly 
referable to the Serlularuta. 

There can be little doubt but that the lamr bmI angnlar 
family of the Graptalitida should realljr be fo6k«d spon aa 
exiinci Hydmaa, tliouxh good authorities ttiD ffaee Utcm 
amongst the Piiytoa. Aa regards their diWrij;— two bctg 
are chiefly noticeable; In the tirst place. ttoGafMile; c«c|« 
the doubtful genus Dictytmema, has hitherto bavfaad to oc- 
cur above the Silurian rocks. 



V 

Ffc. ,»^DId,m^H^ 'Vim-, 



The Graptolites nuy tiierefore 
be regarded as characteristic 
foarils of the Silurian |>erit>d. 
Secondly, the diprionidian 
Graptoliia, or those with a 
row of cdluJn on each side 
(genera I^fltpapsus, CUmatofrraptut, ai»d Duram^pap,uA 
have nertr yet been cextiiiiily shownto occur abt«« ,^ j^ 
y"-°f ^< ^w Silurian rocks. The conno. ,«„ ^ 
*«» fcomptiiiDg the " twin Graptottes^ «^ ,gj , ^ 
•««i«icof the Lower Silurun pcnod lo //^j^ 




J 




MAHUAL 

mtpmt (he po1ypar>' con&ists of two lateral symmetrical 
brandies, with cellules on one side only, xjiringing (torn > 
central point or tiase, which is usually ronHced bjr a little spine 
or"radjdc." 



CHAPTER XI II. 
ACT/NOZOA. 



I. GeHEKAL CUARACTE8S OP THE ACTINOZOA. 2. Ctli 
ACI'EIUi OF THE ZOANTHARIA. 3. ZOANTHAKIA MaLAC 
DERMATA. 4. ZOANTHARIA SCLRXOBAStCA. 5. ZOAM 
THAJllA ScLPJtODKKMATA. 

C1.A8S II. ACTiNOXOA. — The AefifwtM are defined u 
tntmUa tfi/A a diffntnliattd tiigttShv uu eftning bd«K> into 
SQtniitk fiivity, but ttparafat frvm the body-xvolh by att mA 
utg "ftrtfistva/ s/Mu," whUh is dniJeJ m/a a Mries 0/ tom^ 
mtHtt fy Vfriifal parliliDns, or " mfienterif.f ,"!<!• the fiua 0/ 
the rtprpdiKtivt ormtii are att<uh<4. 

The AOinetea (6g. 30), therefore, differ fiindamciitany 
the Hydr&toa in this, that whereas in the latter the digestive 
cavity is identical with the somatic cavity, in the fonocr there 
b a distinct digestive sac, which opens, indeed, into 
somatic cavity, but is, nevertheless, separated from it by 
intervening perivisceral space. As a result of this, the body 
a tyjjical Aciineswn (fig. 29), exliibiLi on transverse section two 
concentric tubcn, one formed by the iJigcKtivc sac, the other by 
the parietcs of the body ; whereas the transverse section of a 
l/ydrotem exhibits but a single tube, formed by the walls of 
die combined digestive and somatic cavity. H 

Histologically, ihc tissues of the Aei'moioa are essentially lh^| 
same as those of tlie /lydrosaa, consisting of the two funda- 
mental layers, the "ectoderm " and the "eododeim." In die 
Aetinnoa, however, tliere is a much greater tendency to a 
differentiation of these into :tperiatised stnicturcs, and in some 
members of the class muscular fibres are well developed. The 
ectoderm, especially, shorn a tendency to break up into two 
bycrs, which are differentiated in opposite directions from an 
interincdiate lonc, and arc termed by Huxley the "ecderon" 
and " enderon," corresponding respectively to the epidennii 
and derma of man. Cilia are oAeii present, especially in the 
interior of the »oinatic cavity, where they serve to promote a 



lerc _ 




OCELENTERATA : ACTINOZOA. 



"5 



ctrcuUtion of ih« digestive fluids conuinixl therein. The snie 
digestive appdiatus in the Aeliftowa noiui.tis oi a tuiniLir 
stoniach-sac, wfakh conununicates freely with the outer world 




't^t. 



«^— A Ttamnnt tKiI« oT u (tritfuHMn, ~ a tXtoriK uc: >Wiill tf ill* 
ri<r : <■ Mc—tffin rwnriitu Ike uoiuck vilb ibe bedr-siUa, ud fividbii Ike 
WMB fci wm n ikMi inio ■ hdidWi gf n«k*l coBpntBHin. B Tn(n>WH heiub 
Mb jy^iAwMn. itmii^ tks linttc nibc fsnaid bf Ab mIIi oT the ttoily. 



by means of the mouth, and opens inrcrioity directly into the 
gcneni body-cairity. In most, the " perivisceral space " be- 
tween the body-walb and the digestive sac is subdivided into 
compartments tiy x aeries of vertical laroelbe, which are called 
the "mesenierirt" (fig. 30, b). Upon the faces of these 



rii- 







ue bume the reproductive organs in the form of bond-like 
ovaria or kpcrmana. 

Thrcad-cclh, ol^cn of very complicated >injcturv, arc almost 
sniversallv present, some of the Ctenofh^ra having been asserted 
to be irilnoul them ; and some of the AaimiM arc able to 
sting veiy severely. 



Il6 MANUAL OF ZOOLOGY. 

A nervous system has not yet been proved to exist in any of 
the Actinozoa, except in the Ctmopliara, and in none are there 
any traces of a vascular system. 

Distinct reproductive organs occur in all the Aoinataa, but 
these are internal, and are never in the foiro of external pn>- 
cesses as ' in the Hydrosoa. Sexual reproduction occurs in all 
the members of the class, but in many forms gemination or 
fission constitutes an equally common mode of increase. 
Some Adinoaea, therefore, such as the common Sea-anemones, 
are simple organisms; whilst others, such as the reef-building 
corals, are composite, the act of gemmation or fission giving 
rise to colonies composed of numerous zooids united by a 
ccenosarc. In these cases the separate sooids are termed 
" polypes," the term " polypite " being restricted to the Uj- 
droioa. In the simple Actiriozoa, however, the term " polype" 
is employed to designate the entire organism. In other words, 
the " accinosoma," or entire body of any Aainesooit, may be 
composed of a single " polype," or of several such, produced by 
a process of continuous gemmation or fission, and united by > 
common connecting structure, or cdnosarc 

Most of the Actinozoa are permanently fixed; some, like 
the Sea-anemones, possess a small amount of locomotive 
power; and one order, the Ctmophora, is composed of highly 
active, free-swimming organisms. Some of the Actituaa are 
unprovided with any hard structure or support, as in the Sea- 
anemones and in all the Ctenophora; but a large number 
secrete a calcareous or homy, or partially calcareous and par- 
tially homy, framework or skeleton, which is temied the " coral," 
or " corallum." 

The Aainoxoa are divided into four orders — ^viz., the Za- 
antharia, the Alcyonarta, the Hagoja, and the Ctmopiuira ; 
but the last is sometimes placed amongst the Hydresoa, and it 
has been recently proposed to remove the Rugesa also to the 
same class. 

Order I. Zoantkaria.— The Zeantharta or " Helianth<»d 
Polypes " are defined by the disposition of their soft parts i» 
multipUs of five or six, and by the possession of simple, usualtf 
numerous, tentacles. TTiere may be no eorailum, or rarefy 4 
" sderobasic " one. Usually there is a " sclerodermic " coratlum, 
in which the sepia in each eorallite, like the mesenteries, tire ar- 
ranged in multiples of five or six. 

The Zoantharia are divided into three sub-orders, the Zeait- 
iharia malaeodermata, the Z. sclerobastca, and the Z. sderodtr- 
mata; according as the corallum is entirely absent or veiy 
nidimentaiy, is " sderobasic," or is " sclerodemiic." 



CCELENTERATA : ACTINOZOA. 



117 



So»«RDER I. ZoAXTHARiA Malacudemiata. — In Oiis sec- 
tion of th« Zaanlharia there is cither no corallum or a ver>' ni- 
dtmcnUry one, in the form of x few .tcattered spicules. The 
" actinoioma " tt usuaUr composed of hut a tingle polype., 
(The term " actinotocDa ' IS a veiy convenient one lo cxijress 
in the AftimnM what " hydxosonu " expresses in the Hyiirotoa, 
Mmcly, the entire organism, whether simple or compound.) 

There aic three families in this section, of which the Arti- 
nida wtU require a somcvrhai detailed examination, since they 
Biay b« taken a& typical of the entire class of the Acimou>a. 

Fjuiily I. AcTiNiD.r.. — The monbers of this family arc 
commonly known a» Sea-anemoncj, and are di.itlnitui«hed by 
hating no evident trorjllum, by being rarely coinjiotind, and 
by having the |)OweT of locomotion. 

tllic body of a Sca^anemose (lig. 31, <>) is a tnmcnied cone, 
or « short cylinder, tcnncd the " column," and is of a soft, 
leathety ooonstencc. The two cxtrcniitica of the column are 




(After CoB&) 

termed respectively the "base" and the "disc," the fonner 
confttiiiitintf the sucker, whereby the animal attaches itself at 
mU. whilst the mouth is situated in the centre of the latter. 
In a few cases (Orianfius and /'MtAia) tlie centre of the base 
b perforated, but the object of this arraiigAment Is imknown. 
Between the mouth and the circtimfcrencc of the disc is a. &it 
■pace, without appendages of any kind, termed the " iieristomial 
■pact:" Round the circumference of the disc an- placed 
nataoQus tentacles, usually retractile, arranged in alternating 
tew^ ukI amounting lo as tmnras 200 in Dumba in \bft 



118 



MANUAL OF ZOOLOGY. 




common Adinia. The tentacles *re tubular prolongations ol 
the ectoderm arul enilodertn, containtii); diverluiula from the 
somatic chambers, and somctiinci hovinij apcrturcj at their 
free cxtrcmitic*.. The mouth IcaiU directly into ihc siomach, 
iriiich is a wide membranous tube, openine by a large apcT' 
lure into the general body-cavity below, and extending about 
hatf-way between the mouth and the base. The vridc vp^^ 
between the stomach and colunin-woU is subdivided into 
a number of com|iartment3 by radiating vertical laineUse, 
termc«i the " immary mesenteries," arising: on the one hand 
from the inner swr&ce of the Ixxly-wall, and attaclted on the 
other to the external surface of the stomach. As the stomach 
is considerably shorter th.tl tlic column, it follou-s that the 
inner edges of the primary mesenteries below ihc stomach are 
free; and these free edges, curving at first ouiu-ards and then 
doiraward and inwards, arc ultimately attached to tlie centre 
of the base. Besides the primaty raeacntcries, there are other 
lamellae which also arise from the body-wall, but whidi do 
not reac:h so far ax the outer aur&ce of the stomach, and are 
called " secondary " and "tertiary" mesenteries, according to 
their breadth. The reproductive organs are in the form of 
reddish bands, which contain ova and spcrmatoioa, and arc 
Mtualcd on the faces of the mesenteries. Most of the Aaima 
are dioecious — that is to say, the same individual does not 
develop both ova and spermatozoa. Along the free margins 
of the mesenteries there also 04cur certain smgut-ir convoluted 
cords, charged with ihre-id-cells, and termed "crupeda," the 
function of which is not yet imderslood. It is believed, how- 
ever, that the apertures, termed "cinclides," in the column- 
walls of some of the A<linu/a, are for the emission of the 
ctiq>eda. No traces of a nervous system have as yet 
proved to exist in any Actinia. 

The embryo of the Adiniis is a free-swimming dliaied' 
body, at first rounded, but afterwards somewhat ovate, 
rudimentary mouth is soon marked out by a dqtrcssion at the 
larger extremity' ; thread-celts ai>]>cnr as a layer in the ecto- 
derm ; a fol<l IS prolonged inwards from the mouth to baa 
the digestive sac ; and the pKmitive tentacles ate at first dtha 
five or six in number, but usually double themselves rapidly. 

Family II. Ilvantuid^c — In this family there isnocorallu 
and the pol)'pes arc single and free, with a rounded or tapcnng 
base (fig. 31, ^). Ilyanthus is in all essential respects ideDtH 
cal with the ordinary Actinia, but it is of a I'ointed or conical 
shape, the base being much attenuated, though whether iis 
haiAt oi life is free 01 &0I, is a matter of tome uncertainty. 



ccB 
itoS 



r the 

"1 

jaiedS 
The^ 
the 
cto- 
onD 
th<f_ 

lumfl 

mtH 

lical 
:iner ils 1 
ertaittty. j 




CCELENTERATA : ACTIN020A. 



119 



fraehiactis is certainly trc<r, and, according to ProlMsor F. 
Forbes, il un not only swim like a jdl^'-fish, bill "it cnn con- 
vert its postcTioi cxticmiiy into a suctorial disc, snd fix itself to 
bodies in the nunni-r of an Aetinia." It is by no means cer- 
tain, however, that AroihiuKlU is a mature foim, and there is 
yatae reason to xupiKKic tliat it is merely the young stage of 
wme at |>rc«eDt unknown Aaimufin. 

Family UL tohvmmx- — In the ZcatitMda UtttK \* a 9n>i- 
cular coralliun, and the poly]>es are Atoched by a Heshy or 
coriaocout base or occnosaic. In Zeanthns the separate pot)pcs 
closdy resanUe snail AciinUe, but they are united together 
al their base* by a thin fleshy ccenosarc 

SuB-oftuER II, ZoANiHARiA SciXROBASicjt. — ^Thc membcis 
vt this Mib-order are always composite, and a]wa)'s posaesa a 
oonllum, but this is " sclerobtisic" and there are no spictilar 
ttssue-secietwnx. 

It a|>]icars advisable to cxi>tiiin here what is undentood by 
the terms " sdcrobAsic " and "sclerodermic." as apnlied to 
corals. The "corallum" is the term which is applied to the 
hard structures deposited by the tissues of any AOui^Mn, 
many of which are so £imiliarly known as "corals." ITsually 
the corallum i.i C()in[ioNe<l of carbonate of lime ; but it may t^e 
OomeoiM, or partly cwmcoiw and p.-irtly calc.amnj». Whiite%*er 
their composition may be, nil coralla may be divided into two 
sections, termed respectively "scicrobasic " and "sclerodermic," 
which must be carefully distingtiishcd hom one another. The 
" sderobasic " corallum, of which the red coral of commerce 
may be taken as the type, is in reality an exoskeleton, some- 
what analogous to the shell of a Cruifaaaa, being a true 
tcgornentary lecretion. At the ume time it is not .t Mc/i' or 
external enveloix;, but it forms an axis, upon which the entire 
actinosoma is spread. The nctinosoma, in fad, is imYrtnf, 
and the " scJcrobasis " is secreted by the fufrr surface of the 
ectoderm. The sclcrobasic corallum is therefore truly "out- 
iide the bases of the polypes and their connecting cccnosarc, 
which, at the same time, receive support from the hard axis 
which tlvcy serve to conceal," — (Greene.) Ifpon this view the 
aderobooiii is tcnned " fooi-secretion " bv Mr Dana. In other 
words, the sdcrobaaic cortl u a hard skeleton which belongs 
solely to the atmaarc of the actinosoma, and which an there- 
fore be produced by a comix>und organism only. 

The "sclerodermic" corallum, on the other hand, is secreted 
tei/Aiii the bodies of the polypes, apparently by the (wwirr layer 
tjT the ectoderm — ihe "endcron" of Huxley — and it is thctt- 
fere termed " tuAuissecreiion " by Mr Dana, la the scVcto- 




120 



MANUAL OF ZOOLOGY. 



i^» 



dcnnic cnntllum nrh pol)pc has x compl«te ukrieton ol 
own, and the entire coral may consist of one such iikeleton, or 
of Kveral such united by the c»lcarcouK ntatlcr of the cucnosarc 




. ,. . _, ' Cun of Atrrru U ria ■muMj. thatrinc 



flC' JL—Mofphalonr orCan)L 

BourtidD, cnbriaij -. ' Dinjifvn ar Kupitc . , ^ , . 

tru ««iiii|Ja>fr»oiwwiu.)f Umipa; ^tntwl tiwlBB of Ca J^Wi^r'K''"' ./ft " 



jtuiartnt 

h pro"! 
c nro-1 



A sclerodermic curallutn, therefore, like the animal which pro- 
duces it, may he Kimnle or comiiosite, accoiding as it is pro- 
duced by a single pulyjie or by several united by a ctenosuc 
ll consists, therefore, of a single ailcareoux cup, or "coralliw;" 
or of several such united by a common calotreoux bond or basif« 
Uie "cocncnchyma." Taking a single "corallite" (fig. 31, ii\ 
ax t}ic lyjic, we lind thai it shows its origin and nature plainly 
in its form. It consists of a cylindrical or conical lube of caiw' 
bonatc of lime, the outer wall of which is called the "theca.'' 
The upper part of the space included by the "theca" is \-acant, 
«nd it is termed the cup or "calice;" but the loo'er pan is sub* 
divided into a scries of chambers, or " loculi," by a scries of 
radiating, vertical, calcareous plates, whidi are called the 
" seina '• (fig. ja. h). 'I'hc septa cslcnd from the inner surface 
of tlic theca towards its centre, where they usually unite to 
form an axial column, called the "cotumclh." Many of the] 
septa, howe^'cT, do not reach the centre, bul stop short ai 
some distance from the columella, often being broken up int< 
upright pillars, called "|iall" The parts thus described a< 
csaentially composing a corallite in a ty|)ical sclcroderniic 
cotallum are related in the most obvious manner to the sol 
sUuclures of the animal by which they are secreted. Th^ 
the " tlieca" clearly corresponds to the " column- wall," or 
gesienl ualJ of the body ; ihc "columella," wlwn ])rc«cnt, 



i 

lyfl 

"I 

le 
;c 

'% 





CCELESTERATA : ACTINOZOA. 

adc to " iImI pan of the endeton which forms the floor of 
the somatic cavity below the digesiivc sacj" whilst the "septa" 
cocrespond to the " mesenteries, " and, like them, arc called 
*" piimary " and " secondary,' according as they reach the colu* 
tnella or liill short of it U'hen there arc several coralliteit, the 
bond of union between ihcm, the "coencnchj-ma," is secreted by 
the *' ecenosarc," to which it corresponds. In many ^e/iuoKia, 
however, the sclcrodcnntc coralhim is not present in the t)pical 
fbnn tdx>rc described, but simply in the form of calcareous 
ifMCuIca or nodules scattered through the tissues of tlie animal. 
There are, abo, tnerobera of the class in which both a sderoder- 
nic and a sderobask corallum arc present, the latter constitiitinff 
the main skeleton, whilM the former i^ rejjreseuted by scattered 
spicules. The conil Uame itself is knou-n as " sclerenchyma," 
and it \-aries considerably in texture, being sometimes extreme- 
ly compact, and at other times very loosely put together. 

From what has been said it will be seen ihtit a scleroba&ic 
corallum can easily be distinguished from a sclerodermic by 
tion ; the former (lig. 33, i) being usually more or less 




Ponlgn ot bnnrh nr AmlntfUni 

, ._ ., , ); » l<«i(iiudiiul uoiMi of /lit 

ktffrti, ■ MknUatc mnl. uMhitlnK ili* •mirnal l«it at conuUK. viih iu *B- 
bedded pa>)>c^ tntipiiMcd hj Ihc inlcrnil uu «r ittUliai (afut JinM 

looth, and being invariably devoid of the cups or receptacles 
for the separate polypes, which arc always )>Tesenl in ihe latter 
(fig. 33. flj- i'he more important variations of detail which 
occur in both classes ot conls injj bt noticed under ihe d\fiei- 



122 




MANUAL OF ZOOLOGY. 



ent families in whkh ihcy occur. Ii only remains to add that 
duuLit has been thrown by cniincDt zoologists upon llic viliA- 
Ity of the general distinction between sderobasic and sdero- 
dermic cords, as above defined. 

Xcturning now to the ZcaniAaria Se/nvbatiea, we find the 
cub-order to contain the two families of the Atitipalhida and 
the H)tat9nfmada (or Hyalochalida). Of these the Anti^ihida 
arc chiefly noticeable because of thdr likeness lo some of the 
G^rg(midei, from which, however, they are readily distinguished 
b^ t&e fact that the number of their tentacles is a multiple of 
SIX, whereas in the latter it is a multiple of four. Anispalhtt 
ilf posseaaes a horny sderobasic corallum, which may be 

nple or branched, and is covered with numerous small 
^Mlypes, united together by a comosarc, and posscuing six 
tentacles each. 

The second &mily, that of the tlyalnnfmada, contains the 
SOHraUed "Glass-zoophytes," the true nature and position of 
which has been a subject of much controversy. E^- Dr Gny 
the ItyalanfmiJce arc believed to be true Aetinet«a, and he 
defines tlicm as follows : — " Social Zoantlioid polypes secreting 
a central, siliceous, intemat, axial coil for their supporl. The 
UIJIXJT half of the coil covered by a uniform cylindrical bark, 
regularly studded with retractile polypes." llic lower portion 
of the siliceous rope-like axis, which looks exactly like a skein 
of threads of glass, is sunk in the sand al the bottom of the 
sea. The upper portion of the /fyalewma is often occupied 
by a cup-sliaped spo»f;c, called Car/eria, which Dr Gray 
believes to be a parasitic Krowth. By Professor* Lovcn, 
Perceval Wright, Wyviile Thomson, and others, the sponge 
Carttria is looked ujion as the true artificer of the siliceous rope, 
and (he polypes are r^rdcd as jur^tsilic, and as referable to 
Palytkca. This last view, by which Ilyahmma would be 
placed .imongst the siliceous sponges, appears, upon the whole, 
to be most probably the correct one. In this case t)icrc is no 
Adinnoiit, as lar as is yet known, which possesses the power 
of secreting a siliceous skeleton, in this respect presenting a 
striking contrast to the PntatM. 

Sub-order III. Zoanthakia ScLKKoi>xitMATA, — ^The mem- 
bers of this suUorder include the great bulk of the coral^pro- 
dncing or "coralligenous" zoophytes of recent seas. Tney 
are defined by the possession of a sclerodermic corallum, the 
pons of whidi are arranged in multiplea of five or six. The 
■ctinocoma may be simple, consisUng of a aingle polype, or it 
may be composite, consistiqg of several poly|>es united by a 
ceeaotaxc 



I 
I 



I 




(XBLEKTERATA : ACTINOZOA. 



133 



he (livitions of th« sulvorder are foiinrtwl upon ihc nature 

of ihc ccmllum, for (he iluc comprehension of which it will 

be neccssar)' to consider some points in connection with these 

^jtnioiitei somewhat more minutely. As already described, a 

^bpical corallite coDsisu of an outer wall or " theca," with a 

^Vup or "oOice" above, and divided below into numerous 

chiunben or " locuU " by vertical partitions or " «et)tii." Often 

ibe lujga or " prinjui^' " sej>u coalesce centrally to fono a 

medixn calcareous rod or " columella." The chief additional 

structures to be remarked are what are kno^n as " tabtil^c," 

and "dissepiments." The " tabulx" (fig. ja, ^ arc transverse 

E tales or floon running at right angles to the axis of (he coral- 
te, and dividing the ihcca into so many horizontal compart- 
■enti or stories, each of which is vertically subdivided by tlie 
when these exixt. As a rule, however, tlte septa are 
It when there are tatnitx, though the two ttructoret co- 
ast in many extitnt corals. The "dissepiments*' .ire incom- 
iransveru; plates, which, " growing from Ihc sides of the 
9t3, interfere, to a greater or less extent, with the perfect 
utintiity of the loculL' — (Greene.) The septa, too, are often 
liraiKheil with xtyliform or spine-like processes growing from 
eir «idek, which often meet so as to form "tnnsver^c pmps 
ending acTon the loculi like the bars of a grate, and termed 
' synaptirula;."* 

'I'he ZooM/Maria Stf/rmirrma/a are divided into the four 
following groupG, founded upon the characters of the co- 
nlhun: — 

I. TMitiafa. — Septa rudimentary, or entirely absent ; tab- 
■be well developed, and dividing the viscera) chamber into a 
Mfk* of stones. 

3. PerfarMa. — Septa well develo|>ed ; dissepiments nidi- 
■Dentary ; ito tabulic. Corallum composed of porous sclercn- 
"lyma. 

3. Aporvta. — Septa well developed, lamellar; no tabula, 
iloin composed of compact, imiierfoncc sctcrcnch}-ma. 

4. I^Auhta. — Septa indicated by mere stria:; thec% pyri- 
occaMonally united by a basal coenenchyma. 

CKHUAnoK AND l^i^ioN AMONGST CoRALs. — As regards 

the modes in whkh the composite corals are produced, the 

>Uowii>g is a summary of Professor Greene's retnarlcs upon 

(ub)eci. (See Oiloiliraitt, y. 185 €< leq.) The produc- 

of the composite Aitinonia ts effected either by gemma- 

or by fissJoa In the former method three voriciic* have 

distinguished, termed respccti>"cly " basal," " parietal," 

" calictuar ' gemmaXloa. 






124 MANUAL OF ZOOLOGY. 

In basal gemination the mode of increase is by means of 
a rudimentary ccenosarc, which is put forth by the original 
polype, and from which the young polype-buds are produced 
It "affords very different products according as the ccenosarc 
remains soft, or deposits a ccenenchyma; appears under the 
form of stolons, or of stouter connecting stems; or even 
spreads out in several directions as a continuous horizontal 
expansion;" in which last case the youngest polypes are, of 
course, those nearest to the periphery of the mass. 

The parietal mode of gemmation is the commonest, and it 
gives rise chiefly to dendroid, or tree-like, corals. In this 
method the buds are produced from the sides of the original 
polype, and they often repeat the process indefinitely. 

Calicular gemmation is not known to occur in any recent 
coral, but it was a common mode of increase amongst extinct 
forms. In this method "the primitive polype sends up from 
its oral disc two or more similar buds ; these, in their turn, 
produce other young polypes, and thus the process is repeated 
until an inverted pyramidal mass of considerable size is j^o- 
duced, alt the parts of which rest upon the narrow base of the 
first budding polype (fig. 32, a). Fission in the Actinotoa differs 
from gemmation chiefly in the fact, that the polypes produced 
fissiparously resemble one another in organisation, and often 
in size, as soon as they become distinct In gemmation, on 
the other hand, the polype-bud consists primarily of a mere 
process of ectoderm and endoderm, enclosing a cxcal process 
of the somatic cavity, and a mouth and other structures are at 
fust wanting. Amongst the coralligenous Adinozoa fission is 
usually effected by "oral cleavage," the divisional groove com- 
mencing at the oral disc, and deepening to a certain extent, 
the proximal extremity always remaining undivided. More 
rarely, fission " is effected by the separation of small portions 
from the attached base of the primitive organism, whose form 
and structure they subsequently, by gradual development, tend 
to assume." 

"The coral -structures which result from a repetition of the 
fissiparous process are of two principal kinds, according as 
they tend most to increase in a vertical or in a hornotUtd 
direction. In the first of these cases the corallum is caspitese, 
or tufted, convex on its distal aspect, and resolvable into a 
succession of short diverging pairs of branches, each resulting 
from the division of a single coratlite." In the second case 
the coral becomes lamellar. " Here the secondary corallites 
are united throughout their whole height, and disposed in a 
linear series, the entire mass presenting one continuous theca." 




CCELEKTERATA : ALCVONARIA. 



125 



these fontu of comllum "are liitbk-to become masthY hy 
union of several rows or tufts of conilitcs throughout the 
vholc or a jwrtion of their height. An Ulu&iration of thi.t is 
aflonlcd by ihe large gyra/^ eorallum of Afeatufnn-j. over the 
aaiftce of whose s]>hcioi(lal mas^ the caliciiie region of ihe 
oombtoed corallitcs winds in so complex » manner » at once 
It) 3ii(g(est ilut rcseinbljLncc to the convolutions of the brain 
whkh its i>0]>ular njtme of Braiiistoiie Coatl has been devised 
to indicAlc" 




CHAPTER XIV. 

ALCYONARtA. 



»Kii IL AtcvONAKiA. — The second great division of living 
ittiiwtM is that of the Aleyonaria, defined by the jxissenioD 
tt-W tight piHHa/eiy-/rtHi^(J ienloila, the mestnterits 
^ somalk dtan^ert bang also s^me multiple^/ four. Tht<ih 
.whtn frtstnt.it itiuaity sH^vbtuittOr tpkttlar ; ifiheae" 
• frtttnl. *r is rartly Ih* iost, there are do septa. 
The Altyonaria or "Asteroid Polypes" differ numerically 
from the Zoantharia in having their soft parts aminged in 
multiples of/our, instead oijive cr six, as in tlie latter. Their 
ICDlacles, too, are pinnate, and are not uniply rounded, 
lumerically the Ateyonaria agree with the extinct onlcr 
tugasa, but the tatter invariably possess a w-cll-developcd 
clen>dennic coralUim, the thccic of which exhibit either septa 
' tabulic, or both combined. 

With the exception of the single genus Haimeia, the Ateyon- 
ria are all composite, their polypes being connected t<^etlier 
common ccenosarc, " through which penneate pTolonga> 
lioDs of the somatic cavity of cadi, fomiing a sort of canal 
tem, whose several parts freely communicate." and )>enT)it 
fiise drcubtion of nutrient ftuidx. As a nile, the entire 
forms a lohaie or brancl)e<l mass. Analomi<:ally the 
of the AUyonaria do not differ in any essential par- 
i&r Erom those of the Zoaatharia; the numerical disniu:- 
bctog the one by vrhich ihcy arc chiefly separated from 
; tnother. The Aieymaria are divided into four families, 
, the Aieycnida, the Tiihiforida, the PenKaluiidir^ and the 

Family I. ALCvoNin^ — This family is diaracleHsed br the 
poMctnon of a fixed actinosDma, which is provided <ff\i^ & 





126 



MANUAL OF ZOOLOGY. 



sclerodennic corallum in the form of calcareous splcnla em- 
bedded in the tiiaucs. The spicules are mostlj' tusifonn in 
slujie, and are {cencmll)- iircicnt bolh in the polypes thi-m- 
selvcs and in the connecting cccnosarc ; but there is no central 
solid axis. 

Mfymtum may be taken as the type of the family, and it 
is well knoirn to fisbeinieQ under the name of " Dead-men's 
iiD(;eTS." It fonns spongy-looking, orancfooloured crusts or 
lobate niasses, which are attached to fubmarine objects, and 
are covered with little stellate aoertures, through which the 
delicate poly])es can be protruded and retracted at wilL I'hc 
polypes communicate wilh one another by an anastomosing 
system of aquiferous tubes, and the corallum is in the form of 
cruciform, calcareous spicida scattered through its substance. 
Id the allied Sarf<>dkt}\m the actinoaoma is creeping and linear. 

Family II. Tubiporid^e. — In ilie Ti^pmAa, or "organ- 
pipe comU," of which T. mmUa is a lamiliair example, there is 
a well-tlcveiopcd sclerodermic corallum, with thecal, but with* 
out septa. The coiallum is composc<l of a number of bri^t- 
red, luliulnr, rylindrical theov, which arc united together 
externally by horiionlal plates or floors, which are termed 
"cpilhccie," and reprcwm external tabula:. The polypes are 
usually bright green tu colour, and possess eight tentacles 
each. 

Fauilv UI. Pesnatulid*.— The Pamahdidtt, or "Sea- 
I)ens," arc defined by their free habit, and by the possessdon 
of a sclcrobasic, rod-like corallum, sometimes associated with 
sclerodermic spicules. 

PettiMittia (fig. 34), or the '* Cock's-comb," consists of a free 
coenoiaTC, the upper end of which is fringed on both sides 
mth feather-like btcral pinnx, which bear the polypes ; whilst 
its proximal end is smooth and fleshy, and is protnhlr sunk in 
the mud of the .tea-bottom. I'his latter portion of the cceoo- 
sarc i» likewise strengthened by a long, slender, stylifonn 
sclcrobasis, resembling a rod in shape, whili^it spicuU occur 
also to the tentacles and caodcrm. The general colour of 
PtnnaiHla is a deep reddish purple, the proximal exticmity of 
the cfxno^rc being orange-yellow. Our Itritish spcLJes (/*<»- 
natuia phofphartix) v.irics from two to four inches in length, 
and i^ found on muddy bottoms in tolerably deep water. Its 
specific name is denve<l from the fact that it phosphoresce* 
brilliantly when irritated. 

In Virguiaria (li^ 35), which, like PennaliUa, occurs not 
uiKoromonly in British seas, the actinosoma is much longer 
atuJ vaon slender than in the preceding, and the polype-b<^ 



\ 





ins fringes are short The polypes have right tentacles. The 
scleroburis is Ln the forin of a long calcareous rod, like a knit- 
tiog-oeedli:, and juart or it tx uAtially naked. No spicuU are 
foand in the (iit»u« of Virgularia. In the nearly-allied Faw- 
nana the polypc-nUss is <iundrangular in shape. 








a A ranfao oT Ibt 

diMa, cb1w(c3; 4 
Portian nf tl4 viam in 
Im dud mvlHIwi. 



Fahilv IV, GORCOKiD*. — In the Gargimuia, or "Sea- 

.bs," there is an arborescent coenosirc pcnnancDtly rooted 

uul provided with a grooved, or sulcale, branched sderobasis, 

wt^di is sometimes associated widi Hue tissue - secretions, 

tcnncd " drrmo-Rclcrilcx." 

The K'Icrobasis of the Gwgmi^ varies a good deal in its 
ooopoaitioa. In some it is corneous, and these havi; often 
been confounded with the Anlipatkida, amongst the Zeanihana. 
Th« distinction, however, beivfccn them is easy, when it is 
icmembertd that the poly]>es in the G<ir^ida have tcniacles 
in miiltiijics of/wr, wniUt in the Anit^thida ihcy arc in tixa. 
^Jlve K:lcioba«i)i, loo, in the former is always marked by gnxnes, 
^^pereai in the Utter it is always either smootli oi «pinu\QUV. 



128 MANUAL OF ZOOLOaY. 

In Isis (lig. 33, b) and Mopsea the sclerobasis con^sts of alter- 
nate calcareous and homy segments, branches being developed 
in the former from the calcareous, and in the latter from the 
homy segments. 

In Coraliium rubrum, the "red coral" of commerce, the 
sclerobasis is unarticulate, or unjointed, and is entirely cal- 
careous. It is the most famihar member of the family, and is 
largely imported for ornamental purposes. Red coral consists 
of a branched densely calcareous sclerobasis, which is finely 
grooved upon its surface, and is of a bright-red colour. The 
coraltum is invested by a ccenosarc, also of a red colour, 
which is studded by the apertures for the polypes, whidi are 
white, and possess eight pinnately- fringed tentacles. The 
entire ccenosarc is channelled out by a number of anastomos- 
ing canals, which communicate with the somatic cavities of the 
polypes, and are said to be in direct communication with the 
external medium by means of numerous perforations in thrir 
walls. The entire canal system is filled with a nutrient fluid, 
containing corpuscles, and known as the "milk." 



CHAPTER XV. 
RUGOSA. 



Order III. Rugosa. — The members of this order are entirely 
extinct, and, with the exception of Holoeystis ilegans from the 
Lower Cretaceous rocks, and a few more modem forms, are 
not known to occur in deposits younger than the Palaeozoic 
epoch. With the soft parts of the Rugosa we are, of course, 
entirely unacquainted, and the definition of the order must 
therefore be founded upon the characters of the corallum. 
The corallum in the Rugosa is highly developed, sclerodermic, 
with troe thecae, and often presenting both septa and tabuln 
combined. The septa are in multiples ai four (fig. 3a, b), 
unlike the recent sclerodermic coralla, in which they are in 
multiples ai five or six. There is, further, no tme coenen- 
chyma. Some of the Rugosa are simple ; but others are com- 
posite, increasing either by parietal or by calicular gemmation. 
Recently it has been shown that some very abnormal Rugose 
corals were provided with a lid or operculum, closing the 
mouth of the calice. In the genus CaJeeola, formerly referred 
to the Bratkie^oda, and very abundant in certain parts of the 



CCELENTERATA : ACTINOZOA. 



129 



fston, the operculum consisted of a liogle valve or 
piece In Gvi^fAyllum four valves were present, and in 
Cytlifhyllum prismaiieum tlvere were four or more valves in 
the opcnrultim. ll is worthy of noiire tiut some recent corals 
{speacs ot /V/jM/tikf. Pammuruni, and oihcn) exhibit also a 
moie oT less complete opcictilum. According to Professor 
AgASSUL, tUc JiugiMl and the liituhUt division of the Zi'oitilharia 
ought not lo be considered as belonging to die Attinosta, 
btU should be pbced amongst the Jfytr&ioa. This radical 
change, however, cannot be accepted without the production 
of very conclusive evidence in iis favour. A strong argu- 
ment against referring the Rtigose and Tabulate CoraU, as 
prc^Msed by Agastii, lo the J/ydrtKoti, is their possession in 
most cases of well-developed itf/a, implying, of course, the 
existence in the living animal of mtimtfies, structures which 
arc »holly wanting in (he Hydrmaa. 

Distinctions het^-ekx the Coralla op theOrocbs of 
AcriNoiOA, — Having now considered all the orders of the 
Actinozixi in which coralLi are developed, it may be as well 
baieily to review their more striking differences. 

In the Arsi place, a sclerobnsic corallum may be distin- 
guished by in&i>cclion from a sclcradcmiic corallum by llic fact 
that ihc latter, unless composed simply 0/ spicules, presents 
the cups or " thcca," in which the polypes were contained ; 
the surfioe of the former being in^uriably destiiuic of these 
ncqrtacles. 

A acleroboHc contllum is found in the tamilies Antif^tAida 
and /Ovi^m>ii>'/<7(/) amongst the 2iiwiMiirw, and in the families 
PtHmatMliJa XrA (J^fff^ulte nmongst the Akyettaria; the fol- 
lowing being the differences between them: — 

I. ^iiJ't>r/4(j/jr.— Sclerobasis spinulousorsmooih; tentacles 
and soft (larts in mulltplcs of six. 

3. IfyaUtemMla {!). — Sclerobosis siliceous, composed of 
nuneratia threads ; tentacles in multiples of 6ve. 

Aaxtf^ttitr.^-ScleiobaMS sul<:ate, free ; soft parts in mul- 
I of fonr. 

Gwgpnuia- — Sclerobasis nilcate, attached )>roximally; 
arts m multiples of four. 

Jennie coralla fall under two he.id$. according as they 
aply composed of scattered spicules, or are (>rowdeil with 
iflor. 

^Uuiar coralla occur in the ZMttf^ria MaUeoHtrm^tla 
foccasionally), an<l in the Abyenida; aiKl no diffetcnco can 
De staled between t)>e coralla themselves. I'hc anim-iis, how- 
ever, ditfer entirely, the sof) /uirts of (he fonner being in mv&< 

( 





13© MANUAL OF ZOOLOGY. 

tiples of five or six, those of the latter being in multiples of 
four. 

II. A theaU sclerodermic cotallum occurs in three distinct 
sections of Adinozca; — i. In the ZoatUharia Sderoderwiat^ 
2. In the Tiibiporida, amongst the Altyonaria; and, 3. In 
the Rugosa; and the following are the distinctions between 
them: — 

I. Zoantkaria Sderodermata. — Septa in multiples of five or 
six, sometimes absent ; tabule often present 

3. Tubiporida. — Septa absent ; (beoe united externally by 
distinct, horizontal " epithecae," 

3. Rugesa. — Septa in multiples of four ; tabulx usually pn- 
sent 



CHAPTER XVI. 

CTENOPHORA. 

Order IV. Ctenophora, — The Ctencp/tora comprise " trans- 
parent, oceanic, gelatinous Actinozoa, swimming by maau ^ 
' ctenopheres,' or parallel raws of cilia disposed in comb-Wu 
plates. No corallum." — (Greene.) 

The members of this order are all free-swimming organisios, 
and they are placed by many amongst the Hydrozoa, from 
which, however, they appear to be clearly separated by the 
possession of a differentiated digestive sac, as well as by their 
analogies with the Actinosoa, and their generally supeiior 
degree of organisation. 

Pleurobrachia (Cydippe) (fig. 36) may be taken as the type 
of the order, the structure of all being similar to this in essen- 
tial points. Pleurobrachia possesses a transparent, coloudesi, 
gelatinous, melon-shaped body, or " actinosoma," in which the 
two poles of the sphere are tenued respectively the " oral " txA 
"apical," and the rest of the body constitutes the " inteip(4tt 
r^on." At the oral pole is the transverse mouth, bounded 
by lateral, slightly protuberant margins. " Eight meiidicul 
bands, or ' ctenophores ' bearing the comb -like fringes, <■ 
characteristic oigans of locomotion, traverse at definite in- 
tervals the interpolar region, which they divide into an eqiJ 
number of lune-iike lobes, termed the " actinomeres"; bot 
this division of the body does not extend into the immrdirtr 
vicinity of the poles, before reaching which the ctenorihort 
gradually diminish in diamWcT, each terminating in a pomt'— 



tXELENTERATA : ACTINOZOA. 



131 



(Greene.) The nonnal number of the ctcnophores appears 10 
be ci^l, and each consists of a l»nd of%ui{»cc elevated trans- 
versely into a number of ridges, to each of which a fringe of 
dha is attached, so a& to form a comb-like pbic. The cilia in 
the middle of thoe traniversc ridges arc the lonfjesi, and they 
mdaally diminish in length towards tlic sidw, so that the 
torn of each comb is somewhat crescentie. Unides the comb- 
like grou(M of vibiatile dha, PltHr^rathia \s provided with 
two vtiy long and flexible tentacular processes, which arc 
(Uaged on 00c side with *inaUer cinhi. These filamentous 
frocesscs arise c.ich from a sac, situated on one of the lateral 
f Ktinofnercs, within which they can be comptclely and iiisuii- 
tueoosly retracted at the wilt of the animal. 




n|. ]1— Clac^heia. Pltinimkim fittmt. 



The mouth of Plenroh-aehia (fig. 37. a) opens into a fiisi- 
digestivc sac, or stomach (A), tlic lower part of which is 
' with brown cell*, supposed to disdia^e the functions 
Ta liver. I'he stomach opens below into a shorter and wider 
rity {{\. termed the '• ftmncl," from which two canals diverge 
the direction of the vertical axis of the organism, to open 
U the " apical potc." These canals arc known as the "apical 
canals" (/), and their apertures as the "apical pores." >rom 
the Amnd two other pairs of canals are given off. Of these, 
pair — known as ttie " paragastric canals " — turns upwaoK 
running parallel to the digestive sac on each side (d), and 
' " icTtninatinj; cafcally before ^uitc reaching the oral cxtiemity.** 
The ticcond pair of canals ((>— the so-cilled " radial canals"— 
bnncb off Grom the fuoae) iafen/f/, each dividing into two, 



t32 



MANUAL OF ZOOLOGY. 



and then again into two, as they iiroceed towards the , 
phery (^ the body. Thus, the two "primary" radb] cuiali' 
produce four "secondary" canals (i), and these, in turn, pv« 
rUc to eight " tertiary" radial canals (/), which finally Icrrai. 
Date by opening " at right angles into an cqiul number o( 
longitudinal vessels, the 'ctenophoralcanals't/), whose course 
coincides with that of the ci^ht locomotive bands. ThcM 
canals end caecally hoth at their oral and apical extremities."— 
(Greene.) I'hc whole of thi^ complex canal-system is lined by 
a. cilLiie<l endoderm, and a constant urcuUtion of the included 
nutrient Huids is thus maintained. 

Immediately within the apical pole is situated a small cyu 
or vesicle, supposed to be an organ of sense, and tcrnMxl the 




Ffg. *^— Hofpholo^ of Cicflophtm. i. DUcm<uTiUiC truAvene AeetkB *tft/r 

ouil>i / / Tiniu}' niJiil neaU : rTinadt, 

*. LwuinHjInil xcllsn et /'InntnHiUi a Mmilh: j Dtccnin Mvii|: r h» 
ml 1 rf rf^l'aiwuinc tanikli : r r Apkal cuub ; /Cunopbunl aatl : g TmOtk , 



mat 

bal)^ 
small 



"clenocyst" (Al. In structure the "ctenoC)-st" consbu 
sphericaJ vesicle, lined w-ilh a ciliated epithelium, snd 
with a dear fluid, which contains minera) p.irliciw, iMroba' 
of carbonate of lime. Resting ujion the rlrn<x*)'st is 3 
ganglionic mas*, giving origin to a number of delicate fila- 
ments, and generally adtniiied to be a rodimcnury form of 
nen-ous i>'stem. The reproductive organs of P/euivtmka 
are in the form of folds, containing either ova or spemiatoioa. 
and.situaied beneath the endodcrmal lining of the ctenophoral 
canals, one 00 each &id«. 

The embryo Pleutvbrathia is at first rudely cylintlrkal in 
form, a belt of cilia ])assing round llie midlife of its Uidy. 
This soon breaks up into two lateral groups, which eventually 
rfiaappcar altogether, " the ctenophores, at first very broad and 




CCELENTERATA : ACTINOZOA. 



133 



few in number, M an earty period taking on the performanoe 
of their njierui] fiinct ion."— (Greene.) 

As regnrtU the homologies between Actinia nnd i'lturebrtuhiti^ 
ihe fult<)<«ing may be quoted from Prorcssor Greene ; — 

" If now a comparison be made between this nutrient 
^rttem" (the cainal-system of the CtewfAora) "and that of 
Aainia, the digestive sacs of the two organiuns are clearly 
seen to correspond in form, in relative size, and mode <^ 
communkation with tlie xomatie cavity. Hie funnel and 
■pical canals of Plmr^lrraehia, though more distinctly marked 
out, are the homotogues of those |iatW of the general cavity^ 
which in Actinia arc central in j>osition, nnd underlie the free 
eitd of Ihc digestive sac Soslso the paragnstric and radial 
canals may be likened to those lateral portions of the somatic 
cavity of Adinia which arc not included between the mesen- 
teries. Ijuily, the ctenophof:il canals of Plturobrathia and the 
somatic chambers of Actinia appear to be truly homologous, the 
chief difference between the two forms beinK, that while in the 
Ulier the body^duunbers are wide and SL-iiaratetl by ver)- thin 
partitions, they are in Plturchrathia reduced lo the <'ondilion 
of tubes; the mesenteries which intervene becoming very 
thick an<i gelatinous, so as lo consliluic, indeed, the pnncipal 
bulk of (he body." Tlic "' apical " canals, again, by which the 
digestive sac communicates inferiorly with llie external medium, 
may be compared with the perforation which is found in some 
of the Aetintdtc {Cerianlhut and Patikia) traversing the axis of 
the base or foot. 

The rcinaining members of the Ctaiof/u>ra conform in most 
essential rc<q>ccts with Ptmrainufiia, the most imjiortant dif- 
ferences being found in the canal-s}-Btem. For pur^ioses of 
comparison this system may be divided into four portions as 
follows: — I. The "axial system," consisting of Uic mouth, 
nomach. funnel, and apical canals, a. The " paraxial system," 
cOfDpnting the pangastric canals. 3. The " radial system," 
comiming the prirDary, secondaij^, and tertiary radial canals. 
4. The " ctet>ophoraI system," consi-tting of the tubes which nin 
undcrocath the locomotive bands. 

In Bfr»f, which is in other respects ver^- similar to Pleurtt- 
hra^hia, the axial system of canals is the same as we have seen 
in the Utter. The paraxial system, however, consists of tU'O 
pairs of p«n|p8tT>c canals, which, instead of terminating 
caecally, open into a circular canal which surrounds the mouth. 
TTte ctenophoral canals, likewise, open into the oral vessel, 
tnsiaul of terminating caecally as in I^eur^braehia. Laailjr, 
tbc radial system is not devclojied, the ctenophoral canuk 



134 MANUAL OF ZOOLOCy. 

simply curving round towards their apical extremities, and 
opening into the funnel directly. 

Amongst the Beroida the mouth extends entirely across tiie 
oral extremity of the body; hence they have been termed 
Eurystomata, the term Stmostomata being applied coIlectiTely 
to all the other Ctmophora. 

The BeroUa further differ from Pleurebrathia in being 
destitute of the long tentacular appendages so chaiacteristk 
of the latter. 

In Cestum, or " Venus's Girdle," " elongation takea place to 
an extraordinary extent, at right angles to the direction of the 
digestive track, a flat, ribbon-shaped body, three or four feet is 
length, being the result." 

Divisions of the Ctenophora. — The following arrange- 
ment of the Ctmophora has been adopted by Gegenbaur (sec 
Greene) : — 

Order CTENOPHORA. 

Sub-order I. Slauilomata. 
Family I. Callymmid*. 

Body furnished with a pair of anlero-posterior orsl lobes, ud other 
smollec lateial appendages. Ttntacla various^ turned towanli the 
moulh. 
Family II. CestiDjE. 

Body ribbon -shaped, extended in a lateral direction, irilhoat on! 
lobes. TaUacla two in Dumber, antero-poatcrior, tuitied towards ihc 
mouth. 
Family HI. CALLiANiBiD.t. 

Body produced into a pair of wing-tike lateral lobes, bearing the cteno- 
phores. Ttntailfs two m number, lateral, turned from the month. 
Family IV, Plecrobrachiad.«. 

Body oval or spheroidal, without oral lobes. Trntatla two in 
number, lateral, turned from the mouth. 

Sub'Ordcr II. Euryilomala, 
FamUyV. BEROin^C 

Body oval, eloi^gated, without oral lobes. Ttntacla abtenL 



CHAPTER XVn. 
DTSTRIBUTION OF ACTINOZOA. 

I. DlSTRlBIJTIOtr OF ACTINOZOA IN SpACE. 2. CORAL REEFS. 

3, Distribution of Actinozoa in Time. 4. Appendix. 

Distribution of Actinozoa in Space. — The Zoanlharia ma/a- 
isiiermata appear to have an almost cosmopolitan range, sea- 



CCELENTLRATA : ACTINOZOA. 



i3S 



Bnemones bciag (bund on almost every coast ; some of the 
trofMcal fomu Jituinitig a very brgc sue. The CttnofiJiara, 
too, have &n almost world-wide di§tribuiion. occiunng in all 
seas from the cjuator to within ihe arctic circle. In Imbit all 
ihe Ctfiw/^a are pelagic, being (bund, like the oceanic //}- 
dntta, swimminu near llie sur^tce far from Un<i. PennatuJiJtt 
and G^rgMNiit iire found in the Kean of the letnpcrale zone, 
but the latter attain tlieir inaxiniuin within the troi)ics. 1'hc 
Red Coml of commerce {Cera/Zium ru^mm) is derived from 
the Mediterranean. 

The so-called " reef- building " Cordis have their distribution 
COndittoQcd by the mean winter temperature of the sea, n. tem- 
perature of not less than 66* being necessary for their existence. 
IIk seaa, therefore, which po&sess the necessary temperature 
may be said to be all comprised within a disUtnce of about 
iSoo miles of the e<iuator on each si<le. Within thae limits, 
however, apparently owinj; tu the inlluence of .Arctic currents, 
DO coial-rcds are found on the western coa-tts of America and 
Africa. They arc found chiefly on the cast coast of Africa, 
the shores of Madagascar, the Red Sea and Persian Gulf, 
throughout l]»e Indian Ocean and the whole of PoNnesia, and 
around the West Indian Islands and the coast of Florida. 

All known AdinczM are marine, no member of llie cbss 
having hitherto been fotmd in fre^h vrater. 

CuRAi.-HRet'S. — A "coral-reef" i.i a mass of conl, sometimes 
tnany hundred miles in length, and it may be two ihotisand 
feet or more in thickness, produced by the combined growth 
of different species of corslligenous Af/iwoHt. As before said, 
a mean winter temperature of not less than 66° is necessary 
for their existence, and, therefore, nothing worthy of the name 
of a "coral-reef" i« to be found in seas so far removed from 
Ihc equator as to possess a lower winter temperature than 
the above. The headquarters of the reef-building Corals 
may be said to be around the i.iUnds and continents of the 
Pacific Ocean. According to Darwin, coral-reef^ may be 
divided into three principal forms — vii.. Fringing- reefs, llarricr- 
Ttct*. an<l Atolls, distinguished by the following characters t^ 

t. /•ringing r-ff/t (fig. 38, i). — These arc reefs, seldom of 
grcmt sise, irhicb may either surround islands, or skin the 
shores of continents. These shore-reefs have no channel of 
any great depth intervening between them and the l.md, and 
the soundings on their seaward margin indicate that they repose 
upon a gcnlly-Ktoiring surface. 

I. Jiarrier-r(fff (fig. 38, j).— These, like the preceding, may 
cither encircle isUnils, or may iJcin continents. The) aic &u- 



136 



MANUAL OF ZOOLOCV. 



tinguuhed lioin frtRging-recfs 1>y th« fart ihnt tlvcy occur attuUlyJ 
at a much greater di^ncc liom land, that there intervenes m.\ 
channel of deep waier between them and the shore, and thai 
soundings taken close to their seaward margin indicate enor- 
mous depths. If the banier-rcef surround an island, it is sorae- 
timec called an " encircling barrier-reef," and it constitutes with 
its island what is called a " lagoon-island." M 

As an example of tliis class of reefs may be taken the great 1 
borrier-rccf on the N.E. coast of Austrati.i, ihc structure of 
which is on a perfectly colossal scale- This reef runs, with a , 
few breaches in its continuity, for a distance of more than 




FW. A— SinuoiH «r canl-Kxfi. i I'llnElnt-fiEri a MaFrlfr-ictr: i Aiolt, aSa 
bvA: ^Otnl-Rtt^cI'ilBiUn Iwdi WPvnlw of k* wilKln Ota ml, fotnaag t 



thatind 01 UcoOB. 



I 



lfaou»nd miles, its average distance from the shore bein^ be- 
tween twenty and thirty niilcs, and the de]>th of the inner 
channel being fcoin ten to sixty ^tlionis, whilst the Ma outside M 
is "profoundly deep" (in some places over i8oo feet). f 

3. Ati>//j (fig. 38, 3). — These are nearly circular reels of 
coni], enclosing a central exiMin-tc of water or lagoon. They 
seldom form complete ringx, the reef bcin^ usually breached 
by one or more opening, which are always situated on the lee- 
ward side, or on that side which is most completely sheltered 
from the prc>'ailing winds. In their suucture they are iden 
ticaJ with "encircling barrier-reefs," and diller from these 



hese only I 



CCBLENTERATa : ACTINOZOA. 



^37 



the Tact that the lagoon which they enclose does not contain 
i&land in its centre. 

If a cora]-Teef be olwcned— My a poitton of an encircling 

ierrecf~th« foKovring arc ihc general phenomena which 

nuy be noticed. The general shape of the reef is triangular, 

Enmenting a sleep and abrupt wall on the seaward side, and 
ivtng a long and gentle slope towards the land. The outer 
margin of the reef is exposed to t)ic beating of a tremendous 
surf, whilst the soundings taken Just outside the line of break* 
^^ETs alwars indicate great depths. The longer inner slope is 
^Kuhed D^ the calm w.iten of the inner la^on or channel. 
pW>ie reef is only very partially composed of living corals, which 
are found to occupy a mere strip, or lonc, along the seaward 
margin of the reef, whilst all above this, as well as all below, is 
constituted by dead coral, or " coral-rock." 

As to ^ method in whicli such a reef is produced, the fol- 
bwiDg facta liave been established : — 

A. llic coral -producing polypes cannot exist at levels higher 
than extreme lun- water, exiiosiiie to the sun, even for a short 
period, proving rapidly fan). It follows from llii.s that no coral- 
reef can be raised above the level of the sea by the efforts of 
its boildets. The agency whereby reefs are raised above the 
nuboc of the sea. is the denuding power of the brcakcis which 
eotuuntly fall upon their outer margins. These detach large 

^rnasses of dead coral, and heap them up in particular places 
^Kniil an isbnd is gcadtully jirodiiced. Tlie fragments thus 
p^ccumulaied are compacted logelhcr by the finer detritus of 
the reef, and arc cemented together by the percolation of water 
holding carbonate of lime in sohition. In this way the tipper 
surface of the reef, along a line of greater or less breadth, is 
more oc less com]>lcie1y raised above the level of high water. 
It is obvious, however, that the reef might be entirely de- 
stroyed by a continuation of this process — the sea being quite 
comitetcnt to undo what it tud done — unless some counteract- 
ing lorce were brought into pby. This counteracting force is 
(bund in the vital activity of the living condx which form the 
tcawud margin of the reef, and which, liy llieirgrowth, prevent 
the sea from aheays destroying the masses of sediment which 
it may have thrown ii|). 

B. The coral-producing polypes cannot exist at depths ex- 
ceeding some 15 to 30 Ctthoms. It follows (rom this that no 
ooral-rcef can be commenced upon a. sca-bottom deeper than 
about $0 bthotos. The question now arises — In what way 
have reefs been produced, which, as we have seen, rise out of 
depths of 300 fathoms or more? This question has been un- 



138 



MANUAL OF ZOOLOGY. 



Sirered by D»wln, who showed that the jiroduclion of iMttier- 
recJs and tttolU was tcMy \o be ascribed to a gradual subst 
dei)c« of the foundations upon which they rest Tliug, if a 
fnngtng-recf which sunounds on island is supposed gradually 
to sink beneath the sea, the upward growth df the corals will 
neutralise the downward movement of the land, so tai, at any 
rate, that the reef will appear to be stationat}', whil.ii it is 
really growing upwards. The island, however, an Mibsidence 
goes OD, will gnulually diminiiih in sixe, and a channel will be 
lonned between it and the reef. If the depression should be 
still continued, the island will be reduced to a mere peak in 
the centre of a lagoon -, and the rccf^ from a " fringing-recf." 
will have become convened into an " cncirding barrier-reet" 
As the growth of the reef is chiefly vertical, the continued de- 
pression will, of course, have produced deep water all round 
KcC If the subsidence be continued still further, the cen- 
al peak will disappear altogether, and the rct-f will become a 
"^more or less complete ring xurrounding a central expanse of 
water ; tliui l>ecoming converted into an " atolL" 'I'he pro- 
duction, therefore, of encircling barner-Teefs and atolls is thus 
sceD to be due to a process of subsidence of (he sea-boUom. 
The existence, however, of fringiDg-ree& is only possible whca 
the land is cither slowly riiting, or is stationary ; and as a mat- 
ter of fact, fringing- reefs are ofieii found to be conjoined with 
U[)ni:icd strata of jJOit- tertiary age. Atolls and encircling bar- 
rier-reefs, on the other hand, arc not found in the wcinily of 
active voira noes— regions where geology teaches us that the _ 
land is either stationary or is undergoing slow upheaval. ■ 

C. Diflcrcnt portions of a coral reef ore occupied by differ- " 
ent kinds of corals. According (o Agassis, tlic basement of a 
cor&l-reef is formed by a zone of massive Attneam. These can- 
not flourish at depths of less than six fathoms of water, and 
consequently when the surface of the reef has reached this 
level, tlie Aitrecant cease to grow. Their place is now taken 
by MeanJrinas (Brain -corals) and Perites; but thcie, loo. can- 
not extend above a certain level. Mnally, the summit of the 
reef is formed by an aggregation of less massive corals, such ai 
Madrtpirida, Mi/Itforidtf:, and GcrgffniHo. 

DisTRiiivTioN or AcTiNoxoA IS TiME. — With the single ex- 
ception of the Molluscs, no division of the animal kingdom 
contributes such important and numerous indications of >tsfl 
(KUil existence as the Admosem. " 

In the I'alaioioic Rocks the majority of corals belong to 
the division Augota, these seeming to have filled the place nowj 
ttkea by the sclerodennic Z-jaaiAaria. The order Jiugesa ' 



I 



iHce now J 



CCELENTEJtATA : ACTINOZOA. 



»39 



ilirdy roteozotc, with the single exception of the genus IIoU- 

ystit which is represented in the Secondary Koclcs by a single 

ccics (viz., //. tifgans, from the lower Greenland) and * few 

Tcrtiajy forms. In the lower Palaioioic Rocks the Xugi/sa 

are especially abundaDl ; but in the Pemiian formation the 

order is represented by the single genus Pciyoxlia. 

The '/oantharia Sdere^iermata, thoiif;h aiuining tlieir muxi- 
mum at the ptesenl day, nevcrtlicleui arc well reprcsenle<l 
in past liroe, beginning in the Silurian period. One Mibdi* 
vision of this group, the 7'ubufysa, is entirely confined to the 
Pabeounc Kocks, and .inolher, the TainliHa. is chiefly Palno- 
toic The /'frfamta and Ajii'resa, on the Other hand, arc mote 
abundant in the Mesozoic and Kainozoic Epochs. 

The Zaantkaria SeiervbasUa are hardly kno«'n as fossU, but 
the Uiocene deposits of Piedmont (Middle Tertiary) have 
yielded a species of Aniiftaihes. 

The Zaantkaria Malait^ermaJa, from tlie soft nature of tlieir 
die*, are obviously incapable of leaving any traces of their 
: ; thotigh we arc by no means therefore justified in 
crling that they did not exist in past geological epochs,. 
The Aitji^Horia are very doubtfully represented in rocks 
aider than the Chalk ; the Lower Silurian fossil called Prv 
lirxaiaria being more probably referable to the Hydrotoa. 
nc of the Peanatulida (vix., Grapkularia) hax been found in 
be London Clay (t^enc), and the same formation has like- 
rise yielded t«<) species of Gorgonida {Mopiax^nA. Wfhteria), 
tie genus CoraiJivm has likewise been found in deposits of 
htioccnc age. 
TtteOvw^^A^ff, being entirely destitute ofany bard structures, 
not known at all as occurring in the fossil condition. 

AmitDuc uiviNo A TABUukK ViKw or the Divisions or the 

ZoAXTHAKU ScLEKODuiMArA AMD KuooM (AFrca 

Milxk-Edwasiis akd Jlims IIaimi). 

A. The Zt^ilJktria SHtrrJirmatti ars defined by the potwuinn of a 
lerodcnnk Donllum, the oartt of nhidi arc atnmi^ in multipla of fiv« 
' •!<. Sepu gencrall)' well derctoped, bill not combined, u a rule, with 
■balK. 
The foflowiag chief diviiioiu of the Ztontharia StlettJrrinat:! arc, vrhh 
I a)l«nci(MH« tho«e irdopled by the aUm-iacalioned authorities t— 

TABCLATA. — Septa mdiTnentarjr or sUcnt : labulK well developed, 
tlividinc lh« vbceral chamber into a series of itoric*. 

I. TturHU. — CeraOuai nuMive ; a dense nNiriout coneticbjrma forsitd 
b]r ibe taiemi niuon of the lepta j tatnue numeioui. 

X FaiMtitidm. — S«fU and coroUitc* diillnct ; little or no true COtneO' 
chfVia. 



■40 



MANUAL OF 200L0GV. 



3. Sniittt^iJa. — C orallum Kiboretcent; (deKnchynui tbundaat 

compaci ; intniljjE few. 

4. UUiiftriitit. — ConJlum muirive or fcJlactou* -, tcpta iiot numcrowi ; 

■cIcnEncbyina tabular or cclluht. 
IL PxKmftATA. — Scpla well developed i na t>but« ; dittcpimenti roJI- 
inontMy; idcrenchixiiit poiuui. 

5. £ufitammiJit.-~Ciyiai\tiiii simple or oompMite( tepUwcU developed 

and UmdUr ; colnmelln tpongioK. 

6. AwdMr^^^onillumcompowdofsponer, relicnlaud KlerenchvoM. 

Septa never lamellar, but cotultiln); wholly of a more 01 lot detinilc 
«C»el of trabecular ; no ubultr. 

7. Jlfyd nf tndt, — Corollum usually cumpovitc ; cimsDchyma abandaM 

vul tpMijpr ; Ihecn: por'xu, not distinct fiom tbe cciiitncliyina ; 

acplB diiimct, bul slightty petfarate. 
I] I. ArOROM. — Septa well developed, completely lamellai', and primilivclj' 

coiulMing of iix elementi ; no tabiilie ; tcleicnchyniB imperfnrate. 
i. Au<pUir.— Coiallum diinplc or compound ; thecc 111 developed, and 

Mmcwbat poroiu ; no diMCplmenla or tabula: ; tynapticul« ounct- 

oua. 
9. AtlnnAt. — Conlluni (imple or oom^mind ; no proper ecmoiMhyma ; 

nnmeroiu dilsepiaicnis ; no kynapiiculT. ConllilM well denned, 

and ■epaiated from one another by petfcci walk 
la Ov/iJnAr.— Coratlum composite 1 iirnicachyma abundant and com- 
pact ; diuepimenU Tew in number. W'jlliof ihe cim!li1e» viihout 

[wrfonlioni, not dlMinct fiiim [lie racncnchjfma. 
II, /iiriinMUriir. — Corallum iisuaUytimple; nuc.minch)'nia; aeptawcU 

developed ; no diucpimcnti, nur lynapiiculie. 
IV, Tt/Buu^tui.-'Septa indicated by mere iinz^i thccxprrironni conlfitet 

tomeliinci connected by a creeping bual oonenchyroa. 
II. AubfirrH^. —This being Ihe onI<r fnmilv In the TiiMtaa, iu chatae* 

terf are necnurily Ihe ume >i uioie of the division itielt 

B. Order KUOOSA.^-Characlerited by Ihe iiouenion uf a tctcrodermic 
COnllum, unially with tcpta and labulx combined, the former bcinc in 
milltipln of four. The coralliiei arc alwap diilincl, and are never united 
togclAer bf a otenenchyma. The tqiia are luuillv innMnplcte. bat are 
never porouSi and never bear lynapliculic. The order ia divided iota tbe 
rolloHin); fnur familiet; — 

Family t. SttiinJ^. 

Cunllum limplc or compMitc ; *cpls Incomplole, united by laaiellar 
diMPpiments ; four large primary lepta, fomiin|[ a croM. 
Famnv a. CyalMajnmJa. 

(^lallum nmplc : Kpucomptelc) nodiitcpitDeauoitabulK; anth- 
out four piiinary icpU. 
TutSXfZ. C^HurfhyJlOit. 

Coiallum ample or composite ; lepta Incomplete ; tabuUr^rnmlly 
pretcnL 
Family 4. Cyitif*}Jlida. 

C^rallum aimple, compoted dilefly of a reticular mats, villi btu 
flight InKet ^ icpta. 



I 



HI 



ANNULOIDA. 



CHAPTER XVIII. 
Gbheiul Characters or the Ankuloida. 2. General 

CHAXACTEKS of IHR ECHINODEHHATA. 

tiXGiMM ill. AxNUi-oiDA ( - Echinswa, Allman).— This 
ngdum was proposed by Professor Hiixlc}' for ihc rcccp- 
of ihe two groups of the E<hin£«iermata nnd the Siolttida, 
' which ihc fomicT belonged (0 the old sub-kingdom RnJiata, 
thilst the bller was fomicriy classed witli itlc Annu/esa. The 
'uine sections hive been grouped by Professor Allman together, 
under the name Ediiiwioa; the Jitftifira, however, being ex- 
cluded from ihi.s (ti\-iKioTi and eliLixeil wiih the Annulosa. Hy 
others agiin, the Annulaida are lookc<l tipon as a section of the 
Anntikia, and not as a distinct sub-kingdom. Provisionally, 
however, it seems bcsi to regard the Annuloidet as one of the 
priniary divisions of the animal kingdom, it being impossible, 
in the meanwhile, to frame 3 definition common to it and 10 
the Annulma, The name Vtrma hits sometimes been etn- 
ptoyed to designate the suli-kin^om Anttulaitla, certain daues 
Ming sometJRKs teroovet! el«ewhere, or certain others being 
added. lit it» moti modem tigniflcation, the term l^rrma 
nuy be held nx Kynonymous with Annuhida, minus the Ethiiw- 
dfrmala and/Au the whole of the Anarthrepedims division of 
the Annuhta. 

The Annulmda an dtstingiiished fy the prama <•/ a iliilirut 
mrtvut lysttm, and tht fMsatim fifan aHmoilary mhoI whuh is 
iMui effjrom ihe gmtral (ovilyoftiu bidy. A pefuliiir 
cf tanali, utuaUy camrnHnUaling roUk the exterior, and 
Htd the" n-atfr-rasaiiar" or " aijutferom" systtm. is present 
' a//; and a Iruf vasaslar apparatus is semetimes present. In 
is tht body »/ fAe adu/t tvmpfised <>/ definik segments, or 
with " bilaleraUy disposed SMcessivf pairs e/ ap- 
pendages'' 

The union of the Echinodermata with the Seoitdda in a single 
ab-kingdom, as proposed by Huxley, must be legardoi t& % 




142 



MANUAL OF ZOOLOGY. 




purely provisional arrangeiTHnit. Many other cbssificatioRl 
have been proposed, each with some ohviotis itdvantagea and 
some disadvantages. Perhaps the most natitr.-il amngcmcDt 
would be to establish a separate sub-kingdoni for the EMiuJtr- 
mala, and to group the Sceimda with [he Anarlhropoda under 
the name of Vermel. In the confcs.scdly imperfect stale of our 
knowledge, however, it will be as well to retain for tlie present 
the Kub-lcingdom Annnltrida. 

The AHHuMda aie divided into liwo great classes, the Bthim- 
dermata and the Sivieada. 

Class I. — Echinodermata^ 

The tnembets of this class are known conunonly as 
urchins, Star-fiKhes, Brittle-*lars, Feather-stars, Sea -cucumbers, 
&c., and the following arc their leading char^icteristics. They 
arc all animals which, in the adult condition, show a more or 
less distinctly radiate condition of their p-irls, espectalty of those 
around the mouth ; whilst in their embryonic stages they are 
more or less distincily bilaterally sj-mmetricaL Wliilst radial 
S)-mmetr^- in the great majority of cases i>repondcrates in the 
aidiilt Eehiitodenm, there are, nevertheless, many instances in 
which the fully-grown animal shows distinct traces of bilateral 
symmetry. The external envelope of the body ("perisoroe") 
is either composed of nttmeroiis calcareous plates, articulated 
together, or of a coriaceous integument, in which calcareoas 
granules and spicules are usually developed. In all adult 
EtMimdermi there is a system of tubes, termed llie " ainbi»- 
Ucral system," which generally subserves locomotion, and 
usually communicates with the exterior, lliis water-vascular 
system uirrouuds the comtnenc-ement of the aliment-iry CAoal, 
and in almost all cases gives off secondary vessels in a radiating 
manner. An alimentary c^nal is always present, and is corn- 
pletely shut off from the body-cavity. In many, if not in all, 
both neural and hxmal S)-stcnis arc developed. 'ITie ncn-ous 
system in all the adult Hchinsdtrmt is a ring-like gaiigliatcd 
cord, which surrounds tl» oesophagus and sends branches 
parallel to the radiating arabulacral canals. 

The special features of tl)e structure of the Eehin^ermata 
will be noticed un<lcT each order, but it will be aa well to give 
here an absiract of I'rofesvor Huxley's dcMrription of the pfO- 
cess of <levelo]»nent in the members of the class. In thegmt 
majority, if not in all. of the Ethmedermota the impregnated 
orum is developed into a free-swimming ciliated, ovoid etnbtyo. 
Sooa tht cilia become restricted to one, two, or more bandfli 



I 




Vchu 



AIJNULOIDA: ECHINODERMATA. 



l« 



ut generaUjr disposed tmDsvosely to ih« lottK axtt of 
the body, and are in all cases bUalerally iy>nmc:iri<:al. The 
ports of the body which stip|)Drt the cilia are uxually developci) 
tato pnMtiberwoes, or pmcenscs, which are tiynttnctrically dis- 
posed u|K>n the Iwo sitles of the body. "The Inn-a; of Attrridta 
and Ih^lifthurUnt art- devoid of any coniiniioiis skeleton, but 
titose of O^uridta and E{hiHutta possess a \'cry rcnijrk.iMe, 
bilaterally symmetrical), continuous, calcareous skeleton, which 
extends into and supports the processes of the body." In this 
tOge the larva form of the two or<leis last mentioned wax 
deitchbc<l by Midler as a distinct animal under the name of 
Jtutais, (rom its resemblance to a jiuntcr's easel. (Sec gg. 

An atimentai)' canal soon appears in the tarra, forming* a 

carre with an open angle towards the ventral surface of the 

ornniuiL The parts of the alimentary canal consist of a mouth, 

guUetf globular stomach, and short intestine, with a distinct 

anal apenure; the whole being "disposed in a longitudinal 

and vertkat plane, dividing the larval body into two xymme- 

trical halveit." Besides the digetiivc canal, no other organs 

lave Iiitlieno been discovered in these larva;. In the further 

pro c e s s of devclopoMiit, "an involution of the integument 

takes place upon one side of the dorsal region of the body, 

so as to give rise to a okciI lube, which mdualljr elongates 

inwards, and eventually reaches a mass of formative matter, 

or bla:>tema, aggregated upon one side of the stomach. 

^AHthin this, the end of the tube becomes converted into a. 

Hbcular voael, from which trunks pass off, radially, through 

^Se enlarging blastema. The latter, gradually expanding, 

^ivcs rise, in the Eihinidta, the Asltridea, the Ofhiurulta, and 

^fae Crittoidea, to the body-wall of the adult ; the larval body 

^pd skeleton (when the latter exists), with more or less of the 

^mitive intestine, being either cast off as a whole, or dis> 

jtpcaring, ur becoming incorporated with the secondary 

oent, while a new mouth is developed in the centre of 

ring formed by the cir<:ulnr vcwcl. The vei.scls which 

from the Litter give off divcrtinila to communicate 

1th the cavities of numerous processes of the body~~tlte so- 

calted feet — which arc the chief locomotive organs of the 

adult. The radiating and circular vessels, with all their 

appendices, constitute what is known as the 'ambulacral 

lien) ' ; and in AiteriJi and Ethmidt this reniarkablc system 

veaaels remains in contmunication with the exterior of the 

jy by canals, connected with perforated portton-t of the 

il skeleton — the so-called 'nudrcponc aina\s' &vA 




144 



MANUAL OF ZOOLOGY. 



] their 
o AtM 

■nodirM 



'tubercles-' In 0pki»tri4i the persistence of any such 
iQiinication bf the uinbiiUcnil sfitem with ilie exterior 
doubtful, anil still more so in CritKitts. In HeiMuriJt no 
such communkation obtains ; the nindrciraiic canals and their 
tubercles depending freely from the circuliu canal into 
perivisceral cavity." 

By Piofcssor Wyvillc Thomson the Urva of the £(Aii 
main is termed the " pseud -cm brjo," since it leads a perfectl; 
indi: pendent existence, and tlie true £tAiw</^m Is asuiillir 
developed out of a portion only of its substance. The grot 
ncculiariiy, therefore, in the development of the £thi>Kdtrmala 
IS found in the poucanion by the larvt uf i^ovi.sionat orgui. 
which may be either 3b»orlic<l or cail off, but which arc not 
converged into the corr»])onding stnicturM of the adult. Thfit 
the Piuttus of an Echinoid potsessec a mouth and alimcniuy 
canal which arc not convened into, and in no way cotrapond 
wit)), the mouth and alimentary canal of the adult. 

'liie Ec/iitiDJertitala arc divided into seven orders — •vit,, the 
CrinsitUa, Cyflifidea, B/itslcidm, Of^iarviJai, Attetwd^a, £cAt- 
twiJM. nnil Heii^lhuroidea. Of th&ie, the first is almoM extinct 
and liic two next are entirely so ; they arc really the lon'Cit 
orders ; but their structure will be better understood if the 
higher orders arc con&idercd first. 




CHAPTER XIX. 
ECHtSOIDEA. 



Orokr Echimoidea.— The members of this order — oommonly 
known ax Scaurrhins — arc chiintcteriNctl by tlte possessioaa 
a kubglobosc, discoidal, or dqiresscd body, cncjse<l in a "test" 
or shell, which is composed of numerous, immov,il)!y ronnccted, 
calcareous plates. The intestine is convoluted, and there is 
a distinct anus. The niniith is usually armed with calcareous 
teeth, and is alu-ays situated on the inferior surface of the body, 
but the position of the anal apenuic varies. The larva isfl 
pluteifonn, and has a skeleton. V 

The " teu " of the Ethineidea is composed of numerous cal- 
careous plates, lirmly imited to one another by their edges, 
an<l bearing different names according to their position and 
Ainclion. In one or two excei>liona] cases, though the essen- 
III/ structure <^ the shell is the same as in the ordinu; fotnu* 




ANNULOIDA : ECU I K ODE RU ATA. 



US 



the plates o( the te«t arc so thin, and arc so united together, 
rlut the entire ic&t becomes Acxiblc and soft. In all recent 
tncmbera of the order the Ic&I is composed of tueniy rows of 
these plates, arranged in ten allcrnaliiig wncs, wluch pass 
from the one pole of the animal to tlie other, each lone being 
composeO of two similar rows. Five of tUme double rows are 
composed of lar]gc pbtex, which are not perforated by any 
apertures (fig. 39) ; the rones forme<l by these imperforate 
plates being termed the " inlcT-iinbuUcral arens." The other 
6ve double rows of plates alternate regularly with the former, 
and arc termed the " smbulacral areas," or " poriferous lones." 







A***iM AfHn^^rieiH (iKHd fnm iban a Iiinr-aabulacn ; # Aobulica. i. 
CoiUl ui««ibrfiK tl HtmmiMtrti MrnnA* flilwpd. < Otutuplala: tf 
ti—iwtj**!* 1 f ^m1 ■iwnvrt ; / KHlRprtrifiHn lubrnje. f '^"f "^ ™ ""*: 



(AIM 



' motuy SI 



1 IW lubcnln In moMfy onulMd en Itji, ■ aDil \ Uit Iht m!k» at 



Each of these cones is compoied of two rows of small plates, 
which ate perforated by minute apertures for the cinisnon of 
the " ambulacra! tubes, or " tube-feet." Growth of the test is 
carried on by additions made to the edge of cich individual 
plate, by means of an orcaniMrd membrane which ]»sscs be- 
tween the sutures, where the plates come into contact with one 
another. Ihe pities of the lest are studded with large tuber- 
ctet, which arc more numerous on the inter-ambulacral areas 
than on the ambulacral, and are wonting on all the plates 
which do not belong to either area. 'ITieae tubercles cany 
jpncs (6k. 40), used defensively and in lo<:o[notion, which arc 
^'Slticuliited to their apket b/ mcanx of a son of " univeriaV" 

K 



L 



146 



MANUAL OF ZOOLOGY. 



or " ball-and-socket" joint Occasionally a small ligamentoos 
band passes between the head of the tubercle and the centre 
of the concave articular surface of the spine, thus closely re- 
sembling the " round ligament" of the hip-joint of roan. B^ 
sides the main rows of plates just described, fonntng the so- 
called " corona," other calcareous pieces go to make up the 
test of an Echinus. The mouth is surrounded hy a coriaceous 
peristomial membrane, which contains a series of small cal- 
careous pieces, known as the "oral plates"; whilst a cone- 
sponding series of "anal plates" is found in the membrane 
surrounding the opposite termination of the alimentary canal 
Surrounding the aperture of the anus at the summit of the test 
is the "apical disc," composed of the so-called genital and 




Pig. 4a. — CiJarii fafillala. (Ada Gout) 

ocular plates (fig. 39, 3). The " genital plates " are five large 
plates of a pentagonal form, each of which is perforated by the 
duct of an ovary or testis. One of the genital plates is la^er 
than the others, and supports a spongy tubercle, perforated \if 
many minute apertures, like the rose of a watering-pot, and 
termed the " madreporiform tubercle," The genitid plates 
occupy the summits of the interambulacial areas. Wedged 
in between the genital plates, and occupying the summits (^ 
the ambulacra! areas, are five smaller, heart-shaped, or penta- 
gonal plates, known as the " ocular plates," each beii^ pev 
forated by a pore for the reception of an " ocellus " or " eye. " 
Besides the spines, which are sometimes of a very great 
length, the test often bears curious little appendages, called 
"p«iicellariie," and often sup^sed to be parasitic Each of 



ANNULOIDA : EClIfNODERHATA. 



u? 



thcs<r consists of a stem, bearing two or three blades or claws, 
which snap together and dose u|>ori foreign objects, like the 
beak of a bird. Their action ap|>ears to be indejiendent of 
the will of the animal, and their true funaion is not known ; 
but ihe>' may be rc^;arde<t a$ peculiarly ino<lilied spines. 

ljO(-umoti<M) in the ReAitwuiea is effected by means of it 
tiDt^uUr sy-Mcm of contractile and retractile tubes, which con- 
MJtute ihc " ambulacnJ tiibcs," or " ttihc-fcctr and are con- 
nected wilh the "atnbulacral system" of aquiferous canals (1i^ 
41). f'roiD the perforated " nudrcporiform tubercle" on the 
tugcM of the genital platt-%, there proceeds a membranous 
cxnal, known aa tite " utone," or "j>:in(t canal,'' whereby vater is 
coDt'cyett from thv exterior to a circular tube, xuiroumling the 
(ENophagux, and coiuaiuting the centre of the water- lascuhir 
or ambuUcral xyxtenu The function of the m.idreporiform 
tubercle appears to be that of permitting the ingrcs-s of water 
fiom the exterior, but of excluding any solid particles, which 
might be injurious. I'hc "circular canal," surrounding the 
(ullet, is situated between the nervous and blood -vascular 
ria^ and gives otT live branchet — the " radiating canals " — 
which proceed radially aloii]; the "ambulaaal areas" in the 
mierior of the shell. In tlii.t courae they give off numerous 
thort lateral tubes — the "tobe-feet" — which pn.i» through 
the " ambulacral pores " to gain the exterior of the test, 
and lennlnatc in suctorial discs. Ik'sidcs the radiating am- 
bulacnU canals, there arc connected wilh the circular canal 
certain veudes of unknown funtiion, known as the " Polian 
vesicles " {aiKpuUa Paiianx). The ambulacral tubes, or tubc- 
Cect, can be proiraded at the will of tlie aninul through the 
pores which perforate the ambiilncral areas, and can be 
again retracted By meant of these locomotion is effected, 
ihe tubcfect being capable of protrusion to a length greater 
than that of the longest spines of the body. The mechanism 
by which (he tiibe-fect arc protruded and retracted is as fol> 
Ums : — I-Laeh tube-fool, shortly after its origin, gives rise to a 
secondary Ulcntl branch, which ienninate$ in a vesicle. These 
vesicles or "amimlla:'' arc provided wilh circular muscular 
Sbrcs, by the contraction of which ihcir cimiained fluid is forced 
into the tube-feel, which arc thus prolniiicd. Rcir.iclion of the 
ambulocral tul>es is effected by proper muscular fibres of their 
own, which cx|>cl again the fluid which has been forced into 
them by the vesicles. According 10 Owen, the terminal sucker 
in each tube-foot of the EMnus is " supported by a circle 
trf five, or sometimes four, reticulate calcareous plates, whkh 
intercept a central forameJi, and by a single, delicate, TCt.KXi- 



148 



MANUAL OF 2O0L0CV, 



laud, perforate pUtc on the proximAl side oT the pceoeding 
groap. The centre of the suctorial disc is pctforaicd by u 
aperture conductiDg to the inteiior of the smbulacral tube- 
foot." This perforution of the suctorial discs of the amlMtbcn, 
though affirmed by Valentin, h di.-nicd by Miiller ; and it ii 
diHicult to believe ihat it would not iminir ilie functions of 
the feet in. the act of protrusion. 

The digestive system of the £(Ainm consists of a mouth, 
armed with live long, calcareous, rod-like teeth, which pt>- 
forate five triangiilnr pyramids, the whole forming a singufar 
structure, known as '■ Aristotle's Lantern." The mouth co* 
ducl& by a pharynx and a tonuous oisiophagiis lo a stomach, 




Fiv. 4r — UoTJMlBty or XcfcinoitH. i. Echluld twa. ■ MMNki * SMUch; • 

a- UiA^TBin of EdiinUL "Hrt ipinu vnd (h* arnbiibo? an ttpnttnitd rm ■ 
■Ball portico of th* tal . iht vfeicuUr tytum U tnm-^t^tHl llw ngf^'at T yJ— 
i( niir*Miiu<I It ihcMuli line a Aiim: / Stuniuh; c Mouh: V md/ Vmniir 
rim mund Ih* ahmtmary nful; ' HesuY ; f 1'*u; 4 Nwou* liw m m* tta 

fnilH; , Actibulatnl riaBof "drculir unij"niunil Iticfullti; »t Poliu iwitlw, 
^nil ciiul ; •> ■■ RadMlinc aiubuUcnl unil; a SnaniUn umbuliicnl ndcia, 
# AmUtUcnl lubpih H"tDb»'fcct'': /Spun: r hlid,*p«v4lvvtA nibwcW 

opening into a convoluted intestine, which winds round the 
interior of tlie shell, and tenninates in a <li.itin(-t anus. The 
inoudi is always situated at the base of the test, and iiuy be 
central, sub.<:entrul, or altojjelber excentiic in ]>oiiition. The 
anus varies considerably in us position, being usually situated 
within the apiod disr, and surrounded by the genital and 
ocular plates, when the test is said to be " regular." Some- 
times, however, the anal aperture is without the apical ditf, 
and is renwved to some distance from the genital plates, when 
the test is said to be "irregular." The convolutions of ihc 
alimentary canal are atucheil to the interior of the test \>y ■ 
deb'catc mesentery ; the luiface of which, as wdl as that of llw 




ANNt'LOIDA : ECHINODERMATA. 



'49 



ImS^metnlirane of the »hell, is richly ciliated, and subtervtK 
the piir)x>vcs of Te«i>iralion. 

Btw pro^ Uood-v.tscular system (tig. 41, 1) consists of a 
tral. fiisifonn, contractile vesicle, or hc^rL This gives off 
one vcssd, which forms a ring round the inlesiinc near the 
sons, and anoUMr which ixisscs downwards, and fonns a circle 
round the gullet, above the " circuUir canal " of the ambulacra) 
syilem. From tlie aii:i] vessel proceed live arterial brunclies, 
«'hi<-h run along the umbiiUcral spaces, and return their Mood 
b^ five bronclm. which run alongside of them in an opposite 
direction. 1'his blood -vascular system has been thought to be 
homologous with the pscttdoha^mat system of the Anndify, 
rather than niih ihc true circulator)' system of higher animalj. 
By Huxley, however, the pscudohaimal vessels of the Anne- 
lidcs arc loolccd upon as homolo(;ous with the water- vasnilar 
system of the Sa^etida, to which the water- vascular or ain- 
butacnl system of the Fchinoderms is iiiiiiucstionably com- 
parable. The harnial system, therefore, of the P.chinoderm.t 
mutt be reipirdnl as something not represented amongst the 
Ann el ides. 

7'hc nervous system consists of a gangltonaled circulai cord, 

which stirroiinds the gullet below, or siiiierficial to, the "circular 

canal " of the iimbuhu:tal system, and which sends five brandies 

along the ambulacntl spaces, in company with (he radiating 

^abulacral canals. 

^B^CTC i* no distinct respiratory organ, but the function of 
KEaiion of the blood ap[M:ars to lie performed partly by the 
vascular lining of the t«1 and t)ie mesentery, and ]>artly by the 
secoDdoT}- ambuUcral vcwcJe*. The perivivcral cavitj- is filled 
with sca-natcr. but the mode In which this is admiiied, or 
renovated, is not known with certainty. According to Ticde- 
nuin, the water gains access to the interior by means of short, 
bniK-hed proccsMrs, which arc attached lo the extremities of 
the intcT-anibulacral areas round the moulh ; but others deny 
that iheie arc perforated by any apertures. These processes 
we ariparently nothing nwre than greatly-developed tubc-fcet, 
uid UMy arc probably homologous writh the crown of feathery 
lcDlad«s surrounding the moutn in the Holoihurians ; though 
this is iKrhaps represented by some very large tubc-fcet placed 
Jul rmind the mouih. 

^■The sexes arc distinct In all the EthinoiJea^ and the rcpro- 

^fclive organs are in Ihc form of five membranous sacs, 

which occupy the tnter-ambulacral areas, and open on the 

encrior by means of the apertures in the (genital plates. In 

the " irreguhu " Echinoidi /*ucJi OA (he " hrarl-urihins " 1 \VieTC 




ISO MANUAL OF ZOOLOGY. 

are only four genital glands, and, therefore, only four genital 
plates in the apical disc 

The Eehinoidea may be divided into the following principal 
families : — 

Synopsis of the Families op Ecuikoidba (aptek Poul). 

Sufl-OKOER I. EcHiKiDA. —Tot composed of no more tluui twenty ram 

af plates. 
a. Spati/ermts. — Mouth excentric, iti front ; knus behind ; ulterior ub- 
bulacrum obliterated ; form obovate. (The M-called " SpuiUn- 
goid " Sea-urchins.) 

1. Ananckytida. — With simple ambuUc™, 

2. Spaitlanguia. — With petaloid BmbnlBcra. 

i. Lampadiformts. — Moutti central, or nearly so; toothed or toothhsi; 
anus more or less posterior, but often mounting high cnou^ to 
enter into tbe genital disc ; ambulicn similar. 

3. Echimmeida. — Toothless ; imbalacia simple, 

4. Cassidulida. — Toothless; ambulacra petaloid. 
j. Clypfitstrida. — Toothed ; ambulacia petaloid, 

6. Echineconida. — Toothed ; ambulacra simplt 

e, Gloiifirma. — Mouth central ; anui opposite the moulli, surTOunded 
by the genital plates. 

7. Cidanda. — Ambulacra prolonged on the buccal membrane and 

destitute of buccal branchix. 

5. fi-^i/jii/if.— Ambulacra not prolonged on the buccal membrane, 

but provided with buccal branchiae. 
Si;b-Order II, FERiscHoecHiNii).^ OR Tesselata.— Corona of the test, 
consisting of more than twenty rows of plates. (The Paleozoic Sea- 
urchins, Arthaafidaris and Pajitckinui.) 



CHAPTER XX. 

ASTEROWEA AND OPHIUROWEA. 

Order Asteroidea (Stellerida). — This order comprises the 
ordinary star-tishes, and is defined by the following characters: 
— The body (fig. 41) is star-shaped or pentagonal, and consists 
of a central body or " disc," surrounded by five or more lobes, 
or " arms," which radiate from the body, are hollow, and con- 
tain prolongations of the viscera. The body is not enclosed 
in an immovable box, as in the Eehinoidea, but the integument 
{"perisome") is coriaceous, and is strengthened by irregular 
calcareous plates, or studded by calcareous spines. No dental 
apparatus is present The mouth is inferior, and central in 
position ; the anus either absent or dorsal. The ambulacral 
ftibe-feeC are protruded fiom grooves on the under surface of 



ANNULOIDA: ECHIKODEKMATA. 



tS' 



the rays. Tbe Urva is rermifomi, and has no pseudembtyonic 

The skeleton of the AtUroidea is composed of a vast number 
of small calcareous plateis ot osticula, united together l^y llie 
eonaceous jieriKome, ko at to form a spede* Oif ohain-armour. 
Bchi'ln thexc the intvgunient is abtmdiinlly sup|>licd with 
spines, lubcrcln, and "pcdiccllarin:." Lastly, the radiating 
ambulacral vessels run underneath a species of internal skele- 
ton, oc<-upying the axis of each arm, and composed of a great 
number of bibteral "vertebral ossicles" or calcnicous plates, 
which are movably articubted to one another, and are provided 
with special muscles b/ which they can be btoug^ht together or 
drawn apart The upper surface of a itar-lish corresponds to 




FIc. wCf^rAi m^At. (After Forbn) 



the combined inter-ambulacral areas of an E<hmvs, and ex- 
hibits the aperture of the anus (when present), and the " mad- 
reponlonn tubercle," which is situated near the angle between 
two rays. The inferior or ventral surface corresponds to the 
ambulacra] areas of an Eekinm, and exhibits ilie mouth and 
ambulacral grooves. 

Tbe nynith \f, central in position, and is not provided with 
teeth ; it leads, by a short gullet, into a large stomach, from 
which a |Mir of sacculated diverticula are prolonged into each 
ny. A distinct intestine and anus may, or may not, be pr» 
sent ; but the anus is sometimes wanting (in the genera, Attn- 
ftttm, Cttneditatt, and J.uidia). 

The ambulacra! sysiem is essentially the same as in lh« 
~ kawiJM, sod u connected with the exterior by means o( lihc 



1S2 MANUAL OF ZOOLOGY. 

" madreporifonn tubercle," or " nucleus," two, three, or more 
of these being occasionally present The ambulacra! tube-lcct 
are arranged in two or four rows, along grooves in the under 
surface of the anns. 

The blood-vascular system consists, as in the £Mtius, of 
two circular vessels, one round the intestine, and one round 
the gullet, with a dilated tube, or heart, intervening between 
them. There are no distinct respiratory organs, but the sur- 
faces of the viscera are abundantly supplied with cilia, and 
doubtless subserve respiration ; the sea-water being freely ad- 
mitted into the general body-cavity by means of numerous 
contractile ciliated tubes, which project from the dorsal sur&ce 
of the body, and arc perforated at their free extremities 
(Owen). 

The nervous system consists of a gangUated cord, surround- 
ing the mouth, and sending filaments to each of the rays. At 
the extremity of each ray is a pigment-spot, corresponding to 
one of the ocelli of an £c/iimis, and, like it, supposed to be a 
rudimentary organ of vision. The eyes arc often surrounded 
by circles of movable spines, called " eyelids." 

The generative organs are in the fomi of ramified tubes, 
arranged in pairs in each ray, and emitting their products 
either into the surrounding medium, by means of efferent ducts 
which open round the mouth, or into the general body-cavity, 
by dehiscence, the external medium in this latter case being 
ultimately reached through the respiratory tubes. In their 
development, the Asteroidea show the same general phenomena 
as are characteristic of the class ; but the larvje arc not pro- 
vided with any continuous endoskeleton. In some Asteroids 
the larval forms have been described under the name of Bipm- 
naria, and in these, as in the Plnteus of the Echinoids, a large 
portion of the larva is cast off as useless. In Bipinnaria asteri- 
gera (Sars) the digestive cavity is a simple sac which sends 
no prolongations into the rays, and the mouth is inter-radial, 
instead of being placed in the centre of the ambulacra! system. 
The mouth of the adult is at this stage closed by the soft exter- 
nal skin of the larva. 

The general shape of the body varies a good deal in different 
members of the order. In the common star-fish {Urasier ru- 
bms) the disc is small, and is furnished with long, finger-like 
rays, usually five in number. In the Cribella (fig. 42) the 
general shape of the body is very much the same. In the 
Solasters the disc is large and well marked, and the rays are 
from twelve to fifteen in number, and are narrow and short 
(abOMl half the length of the diameter of the body). In the 




G«»iastert ilie body is in the rorro or a pentagonal disc, flattened 
on both iidcs ; die true " disc " and niys Itetng only viadble on 
the under Huriuce of the liody. In none of the true M:ir-fixha, 
however, are the arnu ever xhAq>ly sepantcd from the disc, as 
in the Offiiurvid/a, but tliey are alwap an immediate con- 
tinuation of it. 

I'he order Atttrmdta has Veen divided by Dr Cray as fol- 
lows; — 

Obdkr AsraxotttXA. 

Smtirm a, Amtilatrm viltfour nna t^/ftt. 

^mily I. AiitiiaAt. Dai»l trail MiDpIc 
JMm* t. AmuUttm witt Aw riMv t^/ft. 

fdmily 2. Aitnfftttimiiir. Bull llaitiiili, n?itnl villi numerous tuber- 

dn, crowned with ra<ll*tini; ([jlnnac ilip tiii. isWM "puitlx." 
Family y I'tKMfH^iitr. visAl sup^iortnl Iw ruundlih or c)on|ntlcd 

piecet. DOvMvd wiih a tmoolh or granular ikin, piciccvl irith imnuie 

purs bctw«Mi lb« (ubtrcls. 
fuMiiv 4, AlUriiuJa, Boijy liiKoiiliLl or (ij-ramiilal ; sharp-cli^l ; 

tkcletOM TonDtd of fltttUh, Imbricate ptitci ; dorul watt aioglcv 

rardj dovblb 

Ori)i:k Ophiuboidea. — This order comprise* the small but 
Cuniliar group of the "Brittle-stare" and " Sands urs," ofwn 
considered as belonging to the AstemiJM, to which they are 
nearly allied. The bmly in the OfhiuroiJra (fig, 43) ik tlis- 
coidal, and is covered with granules, spines, or scaJet, btit 
pcdiceUarifc arc wanting. Krom the body — which contains alt 
the viaeeia — proceed long slender arms, which may be simple 
or b«anched, but which do not contain any prolongations from 
the stomach, ttor have their under stirftce cxcav.)tcd into am- 
bulacra! grooves. The arms, in &ct, are not simj>lc prolonga- 
t>0Ds of the bodtr, at in the Asltroitlai, but are special appen- 
dages, superadded for locomotive and prehensile ptir))osei. 
Each arm ia encloKcd by four rows of calcareous plates, one on 
the dorsal surface, one on the ventral surface, and two lateral. 
In the centre of each arm is a chain of quadrate osticlea, form- 
ing a central axis, and between this axis and the row of ventnd 
platct in placed the ambulacral vcsseL Each ossicle of the 
ccniml chain is composed of two symmetrical halves, but these 
arc immo\a|ily articulated together, and are not inotable ujion 
one another, ak in the Aitamdea, The mouth is situated in 
the centre of the inferior sutlace of the body, is provided with 
a masticatory apparaluii, and ia surrounded by tentacles. It 
opens directly into a uc-like ciliated stomach, which is not 
continued into an intestine, the mouth serving as an anal aper* 
turc. The stomach is destitute of lateral diverticula. The 
repfoductire organs are stiuated near the bases of ihe anns^ 




«S4 



MANUAL OF ZOOLOGY. 



and 0]>cn b)- orifices on the ventnl mxttct of the bodjr or in 
the intcrbrachial areas. 

It is vGiy <]ucsiionabIc whether the nmbiilacral system in the 
adult OfiAiutviiifii comniunicjics with [he exterior; its pUc* 
u a locomotive apparatus being taken by the anros. The 
radial vesseb of the ambulacnl system arc not provided with 
secondary vesicles or "ampulla," as they are in the Bchinaidet 
and Aiter&idea, and tlie lateral " feet" which they give ofT have 
no terminal suckers^ The madreporirovm tubercle is either 




f\g, u— 4)pUiiroU««. ■ OfMum ttrhmtlit. the CDSiinDn 5and itiul 
> Ofiiiemm mfbcl*. tlis t"r SiiatftUt (tlier KobaV 

placed on the inferior surface of the body or is partially eoo- 
ccaled by one of ihc plates surroundiDg the tnoutlL 

The Inr^a of the Ophiuroidea is plutetform, and is fiuntsbed 
with a continuous cndoskclclon ; and in some, as in Op)^ 
kpis sfuamala, the cchinodenn-body appears within the larva, 
when the Latter lus attained but a very imperfect degree of,— 
devcSopmetiL ■ 

In EuryjJf the body is in the form of a sub-globose disc " 
with five obtuse angles, and the arms are prehensile. In At- 




^^^^ ANNULOIDA: ECHINODERMATA. 1%$ 

^UtvfkytM, the Mciiusa-head siar, the anns arc divided from 
th« bascv first {li<:hoiomously, and then into many branches. 

I In OfAiurj, the Kind-Ktar. th« armh ser^-e for rcpUIton (creep- 
ing), and arc undivided, often exceeding tlie diameter of the 
disc many limes in length, 

The order O/Aiuroidea may be divided into two families, as 
follows : — 

Family t, OfJkmriJia. 

GenUal fiuurei Iwo or bur in number. Arnu 6vc ilwayt tla(|))e. 
F*mii* a. ilUmfAyttij. 

G«uia1 fuasra ttn in nuntlier. Armt five, limple or bnuicheiL 




CHAPTER XXI. 

CRINOJDEA. CYSTOIDEA. AND BLASTOIDEA. 

Order Ckinoidka. — The members of this order are Eehino- 
d^mata, in which the My it ^xed.durin^ Iht ivh<d( or a porihtt 
ti tht fxitfena of the animal, to Ike tea-heltout by mram of a 
tttfgtr or (h^ttr,/ointedy aitd fitxtbU ttalk. The body is dis- 
lioct, composctl of artioiUted udeareous plalcx. bursiform, 
or cup-shaped, and provided with solid arms, which arc pri- 
iB&hly from five to ten in number, arc indepeodcni of the 
visceral cavit)', and arc grooved on their upper surfaces for the 
unlmUcra. (The position of the body beini; revened, the 
Ijfywr surfiMie is x-mtrai; whilst the dortat surface is in/triorf 
UM give* Ofwin to the pcilicle.) The tut>ular prticcfscs, 
however, which are given ofl' from the radiating ambiilacral 
casob of the Criitmita, unlike those of the Echinoidm and 
Atitroidftt, Jirc not used in locomotion, Init have probably a 
respirator)' function. The mouth is central, ^nd looks upwards, 
an anal apcnure being Homcdmcs present, sometimes absetit. 
The ovaries arc situated bcntith the skin in the grooves on the 
VCQtnl cuffaccs of the arms or pinnules, as are also the ambu- 
lacral or respiratory tubes. The arms arc furnished with nu- 
iDCTDUx tatcral branches or "pinnulx." The emlir)-o is "free 
and d)i.alc«l, and develops witliin itNelf a second larval form, 
which beconivs fixed by a peduncle." — (Huxley.) 

Of those CrituHdea which arc permanently Axed to the sea- 
bottom liy a jointed pedicle, there exist but a few living 
romia, of which the best known is the Pentiurinui Caput- 
Mtduta. In this type of the Crin-Adta — laigely rcprcscnlcd 



156 



MANUAL OF ZOOLOCV. 



in post geological epochs — the bod/ is composed of i 
calcareous pUtcs, united together so as to form a cup « 
"calyx," ibc bottom of whkh ts continued into a " column," or 

pedicle, compoxe<l of a serio 
of calcareout: joints or artica- 
lalions. n-hcrcby the nninul 
is fixed to some foreign body. 
The upper part of the caly» 
is roofed over by a series of 
calcareous plates, and is per- 
foralcd by the apertures of 
the mouth aiKl anii^t, the Ut- 
ter being somclimc-t aluent. 
In the recent Kpoics the 
mouth is central, and there 
is a distinct anus at one 
side. The margin of the 
calyx gives origin to the arms, 
which arc grooved on their 
upper (or ventral) mrfaces foe 
the ambulacra. In the liv- 
ing Criiwids the ambutacrsl 
grooves arc continued along 
the upper surface of the ca- 
lyx to the mouth. In the 
Palseoxoic Crmeidt there is 
only a single opening on the 
upper stittace of tJie calyx, 
vhich is sometimes cenUil 
and sometimes lateral, and 
which serves both as a mouth 
and anus. In many cases 
this aperture is level with the 
surface of the calyx, but in 
many sjicciGS it is placed at 
the summit of a long pn> 
jcctiii){ tube, which Is termed 
the ■' proboscis." The nm- 
bulacral grooves in the Falx- 
oioic CrimiJs arc found on 
the ventral surfaces of the arms, as in the living species ; but 
instead of being continued over the surface of the body to 
the mouth, they stop short at the bases of the arms, where Ihey 
gain access to ihe interior of the olI/x by a series of spectu 
apertures.— {fiillingt.) 




I 






(A, ■ llvln| Crinnd {aflir WvviU* Ihum- 
ttia}, fuur Uiaai ()M OMunl M*. • Slttn. 




ANNULOIDA: ECHINODERMATA. 



J 57 



More recently a stalked Crinoid hAS been discovered in the 
_ltlantic and North Sea, aod his been described under the 
'name of Rhiuxriitui Jjt/etmiis (fig. 44). The chief interest of 
ihb form h the fact iliat it belong to a. group of the Criwiilai 
hitheno believed to be exdusiivcly confmoil to die Mcsozoic 
Kocis — vii., the AfiocriniJa or " Pear-etirriiiites.'' In fact, 
RhitatriHtu is wry closely allied to the Cretaceous genus 
Bcurgmturinut, and it may even be doubted if it is gcnerically 
separable from it. The late rcmaikablc researches into the life 
of the deeper parts of the ocean have brought to light seveial 




SUJ 



* FiWil )uuli(. (After ftrbu ) 

new Crinoids, which will doubtless, when fiilly investigated, 
ttUI further 611 up Uic interval between the living and extinct 
n/wJnt. 

In the sctond type of the Criiioiifta — represented in our sens 

the Camatk/ii (fi^ 45), or Featlier-star — the aiitnial is not 

laaently fixed, but is only attached by a stalk when young 

pg. 4j, i), in which condition it was described sa a distinct 

' ies, under the name of PentiKriniu Eurcpaut, In its adult 

lition. however, the Cemalula is free, and consi5U of a pen- 

tagooal diac, which gives origin to ten slender arms, whWU arc 





IS8 



MANUAL OF ZOOLOGY. 



fringed with many marginnl pinnule or " cirri." The motiil 
and anuB arc on ifae ventral surface of the dtic, which in thit 
case is again the inferior surface, since the animal creeps 
about by means of its pinnated atins. The arms, in fad, of 
ComaMa appear lo be purely locomotive in function, and to he 
never employed us [irehcnsile organ^t The animal lives upon 
very minute Drg:inisms, drawn into the mouth by the action of 
the cilia lining the alimentary canal, 'llic dorsal cirri, howe%-cr, 
are employed to moor ihe sninial temporarily to solid objects. 
The mouth is central in position, and the anus, which in ramc 
species forms a tubular projection, is situated on one side. 
Both the arms and the lateral pinnuUe are grooved on their 
ventral surfaces for the ambulacral vessels ; and the pinnules 
also serve for the stipix>rt of the reproductive otgans. It is 
extremely doubtful if the anibulacral s}-steni, in the adidi, has 
any iromniunication with the exterior. The function, in £ict, 
of the water- vancular system appears lo be wholly t«pinnor)-, 
locomotion being entirely cITcctcd by means of the arms. The 
alimentary canal is confined entirely to the disc, and the 
stomach sends no diverticula along the arms as it docs in the 
AtUroideti. The larva or pscudenibryo or Cematula rchua is 
a small ovate organixm, «-ith four transverM; ciliated bands, a 
key-ho1e-sha))ed mouth, and a small vent and rudimenloty in- 
testine, the whole showing no traces of radiation. The young 
Crinoid is produced wiihm the pscudembryo, and develops a 
fresh mouth, anus, and stomach for itself; the first being 
originally on>anal in function, and being placed in the 
of the ambulacral sptem. 

Several species of Camatuta arc knonvn, and the geiiua 
pears to be cosmopolitan in its distributioit. Ine 
OphkrinHs has been funned for species said to posseu no 
more than Ave undivided anns. 

Okdkx CvsToiOEA {Cystidta). — The members of this order 
are all extinct,* and arc entirely confined to the Palscoioic 
period. The body (%. 46) was mote or less spherical, and 
was protected by an external skcleiOD, composed of numerous 
polygonal calcareous plates, accurately fitted together, and 
enclosing all the viscera of the animal. The body was in 
most cases permanently attached to the sea-bottom by means 
of a jointed calcareous " column," or pedicle, but iJits was 
much shorter than in the majority of Criitoidt. Upon the 

* Rfcenllt Profenor LAven hu il«Kriti«d a tltwuUr AuMntUui 1-lchliio- 
derni u ImnE mmt cloMly *llie>cl to, if not tnJy rcfcralile to, Ibr onkr 
0i«mUiw. H« h>i named tlii< euriout rorm l lf/it trm* Sara, ud btliem 
it lebe aeailj related to tht CyiiiuktA geniu AgiUurmitH. 



I 



being 
: centre H 

Dua ap-H 





ANNULOTDA: ECHINODERMATA. 



159 



«pper rorfart of the body yrene two, somctimM three »pcr> 

turt3,ili<rfuTi<:tinn« of which huve been a mutter or considerable 

conUovcrty. One of these is latent) in position, is defended 

by a Kerics of small r^rulatr pistes, and is 

believed by some to be the mouth, uhilsi 

by others it is asserted lo have been an 

ovarian aperture. The view advocated by 

Mi Billiitgs, thii this aperture was the 

mootb, appears from every point of view 

lo be toon probably correct ; or rather it 

was oro-anal, as was alxo the probo^tcis of 

the Pabeocrinoids. The second opening 

is central in position, and is believed by 

Mr Billing! to be the " arabiilacral orifice," 

as it is always in the cenlie of the arms 

when these are present. TTic third ape^ 

tare U only occasionally present, and 't.p^:f^,{^ 

h*]a l-imcfeEonc iLavtr 




fn a second sec- 



doubtiess discharged the functions of an 
antB. 

In some C^ffaUta there were no arms, 
properly speAing, but only small pinnulx. 
tion tne anas were prcseni, but these were bent backwards, 
and were immovably soldered down to the body. In one 
single spcdcB (CffmanKjisfitfs funetatus, Billings) the dcvelop- 
meoi has gone further, tJie arms being free, and provided with 
lateral pinnulde, as in the true Criwidt. 

Many Cysiideans are likewise [>rovided with a system of 
pores, or fissures, penetrating the plates of lite body, and luu- 
ally arranged in definite groups. 'Hiese grxHi|)« are termed 
"pectirwtted rhombs," but their euct function b doubtful. 
By Mr Billings, however, they ate believed, and apparently 
with good reason, to have admitted water lo the body-carily, 
and to haie thereby subserved a respiratory funclion. 

Ordck Bi-ASTOtDEA. — The members of Uiis order, like those 
of the pret:edLug, are alt extinct, and are entirely confined to 
the Palieozutc jwriod. The body was fixed to the bottom of 
the tea by means of a short jointed piilide ; it was globular 
or oval in shape, and com|>oi>ed of Kolid |>olygonaI cakareoua 
plUeSi iirmty united together, and arranged in five inler-ambu- 
lacnl artd as many ambulacra! areas. (These ambiil.-irral areas 
ate termed by H'Coy " pscud-ambulacra," upon the belief that 
they wen not pierced for tube-feet, but that they carried a 
double row of bttle jointed leotacles or arras.) The ambula- 
cra] anas are ^etaloid in shape, having a deep furrow down the 
centre, and itnated Iransveraely. They converge to iht tnwili^ 




l60 MANUAL OF ZOOLOGY. 

which is superior and central in position, and iB sUROUnded bjr 
five ovarian apertures. No arms are present 

The Blastoidea are known more familiarly under the name 
oi Pmtremites, and they occur most commonly in the Carboni- 
ferous Rocks. 



CHAPTER XXII. 
HOLOTHUROtDEA. 



Order Holothuroidea. — The members of this order are 
commonly known by the name of "sea-cucumbers," "tre- 
pangs," or " bfecties-de-mer," and are the most highly organised 
of all the Echittodcrvtata. The body is elongated and vermi- 
form, or rarely slug-shaped, and is not provided with a distinct 
test, but is enclosed in a coriaceous skin, sometimes containing 
scattered calcareous granules or spicules. The ambulacral tube- 
feet, when present, are usually disposed in five rows, which 
divide the body into an equal number of longitudinal segments 
or lobes. The mouth is surrounded by a circlet of feathery 
tentacles, containing prolongations from the central ring of the 
water-vascular system ; and an anus is situated at the opposite 
extremity of the body. There is a long, convoluted intestine. 
A special respiratory, or water- vascular, system is usually de- 
veloped, in the form of a system of arborescent tubes, which 
admit water from the exterior. The larva is vermiforro, and 
has no skeleton (fig. 47). At a certain period of their exist- 
ence, the young Holothurians are barrel-shaped, with trans- 
verse rings of cilia. They rotate rapidly on their long axis, 
and have at this stage been described as a distinct genus 
under the name of Auriatlaria. 

In the Holotlmriee proper, locomotion is chiefly effected by 
means of rows of ambulacra! tube-feet, or by alternate ex- 
tension and contraction of the worm-like body ; but in the 
Synaptida there are no ambulacra, but only the central circular 
canal of the ambulacral system, and the animal moves by 
means of anchor-shaped spicula, which are scattered in the 
integument. When developed, the ambulacral system consists 
of a "circular canal," surrounding the mouth, bearing one or 
more " Polian vesicles," and giving off branches to the tenta- 
cula ; and of five " radiating canals" which run down the 
interspaces betft'een the great longitudinal muscles. These 
/sdialing canals give off the tube-feet and their secondary 



ANNULOIDA : ECIIINODERUATA. 



i6r 



vesicles, just as id the EeMnnt. In the typical fonns there 
arc five rows of tube-feel, bui these may be scattered over the 
whole body, or may be reitrictec) to the ventrul surface. 
There is auo k " sand-canal," which arises from the {.irctiliLr 
cajia], and is tt-rmin.-Hcd by a mad rcpori form lulicrcic; but 
this, instead of opening on the cxttrior, bang* down freely In 
the penvitccral cavity. The Huid, tlicrefore, with which the 
ambulMTsd system is filled, is dcnvcd from the perivisceral 
cavity, and not from the exterior, as is usually the case. 

'I~hc mouth in //oio(Auria is situated anteriorly, snd is sur- 
rounded by a beautiful fringe of branchedi retractile tentacles 
(fig. 47), which arise from a ring of calcareous plates 3n<l into 
which are sent ]>rolongalion9 from the ciicum-oral ring of the 
ambulacral system. Tlie month opens into a pharynx, which 
conducts to a stomach. The intestine is long and convoluted, 
and opens into a terminal dibtation, termed the "cloaca," 
which serves both as an anus and as an apcnurc for the 




T*>*— /a^V.Wi. (After Furtiei.) 

niiston of sea-water to the respiratory ttd)es. From the 
cloaca arise two branched and arliorexceni tubes, the lamina- 
tions of which are jirolubly caxal. These run up towards 
the anterior exwcmity of tlie body, and together consiiiute the 
so<aUed " respiratory tree." The>' arc highly contractile, and 
they pcrfotm ihc function of respiratory organs, sea-water 
bein^ admitted to them from tlic cloaca. The nervous system 
consists of a cord, surrounding the gultel, and giving olTfive 
branches, which run alongside of tlie railiaiiitg anibulacrat 
canals. The generative organs are in the form of long, rami- 
fied, c»uU tubes, which open externally by a common aper- 
ture, situated iKar the mouth. There is thus do trace of that 
radial syinraetiy which is observed in the armngcment of the 
reproductive organs in the other ordera of the EdtmoJrrmafa. 
The vascular system consists of two main vessel*— one dorsal, 
anil the other ventral — connected with a circum-tesophageal 
ring. 



l62 MANUAL OF ZOOLOGY. 

The skin in the Holothuria is highly contractile, and the 
body is provided with powerful longitudinal and ciFcnUr 
muscles, in compensation for the absence of any rigid integu- 
mentary skeleton. Many of the Sea-cucumbers, iD fact, are 
endowed with such high contractility that they can eject their 
internal organs entirety, if injured or alanned. 

In Synapta there is no ambulacial system of tube-feet, not 
respiratory tree. Locomotion is effected by means of little, 
anchor-shaped, calcareous spicules, placed upon little pafHllc 
of the integument. Respiration is effected in the abdominil 
cavity, into which the water is admitted by five openings be- 
tween the tentacles. 

The order Holoihuroidea may be divided into the fcdlowing 
two families : — 

Familjr I. Hidgthiuida. 

Body free, cylindrical, with a conBceous int^uinait ccmtuning 
scstteied calcareous partictes. An ambulacral system alwayi^ anda 
respiratory tree usually, present. 

Family II. Synapluia, 

Body Tree, covered with a coriaceous, sometimes soft, interment, 
containing minute, anchor-shaped spicules, by means of which the 
anima] moves. The ambulacraJ system TudimcnlaTT, not giving riiC 
to tube feel, and not connected with locomotion. A respiratory tree 
sometimes present, sometimes absent. 



CHAPTER XXIir. 



DISTRIBUTION OF ECHINODERMATA IN SPACE 
AND TIME. 

Distribution of Echinodermata in space. — The Criiioidea 
are represented by very few forms in recent seas, and these 
have a very local distribution. The Comaiula are the com- 
monest, and species have been found in most seas. The 
Pmtacrinus Caput-Medusa is excUisively confined, as far as is 
known, to the Caribbean Sea, Rhizecrinus Lo/otensis has been 
dredged on the coast of Norway, and a form believed to be 
the same has been found in the Gulf of Mexico. 

The Aiteroidea, OphiuroiiUa, and Echiito'idea are represented 
in almost all seas, whether in tropical or temperate zones, 
some occurring very far north. The ffololhurotdea have their 
metropolis in the Pacific Ocean, occurring abundantly on the 
coraf-reefs of the Polynesian Archipelago. One species is col- 



annuloida: echinodermata. 



163 



l-irgc numhen, and U ex[)oned to China, whcic il is 
rcganJcd as 3 great ilclkacy. 

OisTKiBUTiuN or Kurt Noiii'.itM ATA IN TiMK. — Numeroas 
rcRLiiiu of E(hui»Jtrmata occur in most scdimcntair rocks, 
l>cgiiming with the base of the Lower Silurian Roclcs, »nd ex- 
Ecndinf; uji to the recent period. ITic two orders Cysteidta 
and Blattotdta, which are the most lowl)- organLied of the 
mttre cU», nre exclusively raheoscMC ; and ilie CHimJta are 
nuRly Fcfenblc to the same epoch. The more highly organ- 
Md Ast(r»i4ta and OphiurmJea commenced to be represented 
in the Silurian perio<l ; l>ul the tichimiJta, with a single excep- 
tion, have no representative (-.irlicr ihnn ihc Carboniferous 
Rocks. The following exhibits the geological distribution of 
ihc dilTercnt ordcre of the EikimdatHat-i in somewhat greater 
letail:— 

1. Ckixoidea.* — The CriHeidfa attained their maximum in 
Jie PalsDOZoic period, from «hi<;h time they have ^{radually 
iiminished down to (he jiriMcnt day. As has iUrcndy been 
icscribed, the Palwo/oic Crinoidea differ in some im]>ort3nt 
Mrticnlars from those which succeeded them. The order is 
veil re]>rescnted in the Silurian, Devonian, and Carboniferous 
Rocks, but especially in the latter; many Carboniferous time- 
itoncs (crinoidal limestones and entrcichal marbla) being 
Umost entirely made ti]> of the columns and separate joints of 
Uftnotds. In the Sc4:ondnr)- Rocks Crinoids are liiill abimd- 
inL In the 'I'riiu the bcaunfVil "Stone-lily" (/iiunnus lUii' 
Wrnii) IS jMculiar to its middle division ( Muschclkalk). In 
be Juntssic period occur many species of Apioerinm (Pear- 
intnnite), Pmtaehnus, and ExSrairmus. The Chalk also 
ibouods in Criituids, amon|{si which is a remarkable un- 
attached form (the 'i\>rtoise-encnnite or AfarmfHet). 

Of the non-pedicuUte Crimidea, nhich are a decided ad- 
^aDcc upon the Mjikcd forms, there arc few iraco; but 
emiins of C«mtUu!-,i have been discovered in the lithographic 
ilate of SoJenhofen (Uolile) and in the Chalk. 

2. Bla>iix>ioila. — Thc.&/iu/M(i^, or Pentremitcs, arc entirely 

* Ai neudt the calyx of Ihe foul! CiiitatJta, the folloiring torms are 
n|4(i)«d 10 ilolviwie'tlt dilTcrcnl jai tt. Tlie Sane ol the cup, 01 calyx, 
i tctncil ih« ' p«t*u,' and it » made up of fii^, four, or ranutlmc* three 
lino, whkh ara tanned tbe "buak" To the " l»t«U " tacorcd iwoot 
htM low* of plat«*, wbich ar« temwd reapeclively Ihe "primary radial),' 
'*MMulary cadiaU," a»d " loliary rodidi," according to tlinr dUiaiwe 
roo* the basalt. The ailUary radiali, which ire ilic ruithetl ccmoved, 
[tve oritin to Ibe anna, and are ocouiuiuUy called the "scapulx' (for 
ait naaon), whilu the (Nunaiy and teconctary radiaU aie called Ibe 




l64 MANUAL OF ZOOLOGY. 

Palaeozoic, and attain their maximum in the Carboniferoui 
Rocks, some beds of which in America are known as the 
Pentremite Limestone, from the abundance of these organisms. 
They are, however, also found in the Silurian and DcvoDian 
Rocks. 

3. Cystidea. — ^These, like the preceding, are entirely Paleo- 
zoic ; but they are, as far as is yet known, exclusively confined ' 
to the Upper Cambrian and Silurian Rocks, being especialljr 
characteristic of the horizon of the Bala Limestone. Forms 
supposed to be Cystideans have been described from the Devo- 
nian Rocks, but their true nature is doubtfiil. The oldest 
known Echinoderms are two extremely simple Cystideans 
('D'ochecystites and Eocyitites) which have been discovered in 
the primordial zone of North America. 

4. AsTEROiDEA-^These have a very long range in rime, ex- 
tending from the Lower Silurian period up to the present day. 
In the Silurian Rocks the genera Palaaster, Staunter, PoLk- 
discus, and Fetraster are among the more important, the greater 
number of forms being Upper Silurian. The next period in 
which star-fishes abound is the Oolitic (Mesozoic) ; the more 
important genera being Uraster, Luidia, Astropecten, Plumasttr, 
and Goniasttr, some of which have survived to the present 
day. Many star-fishes occur, also, in the Cretaceous Rocks, 
the genera Oreailer, Goniodiscus, and Astrogonium being among 
the more noticeable. In the Tertiary Rocks few star-fishes 
are known to occur, but Goniaster and Astropecten are repre- 
sented in the London Clay (Eocene). 

5. OpHitiRoiDEA. — The "brittle-stars" are represented in the 
Silurian Rocks by the single genus Protasler. In the Oolitic, 
Cretaceous, and Tertiary Rocks several genera of OpAiurtridia 
are known ; some being extinct, whilst Others (such as Opkio- 
derma, Ophiolepis, and Ophmomd) still survive at the present 
day. 

6. EcHtNoiDEA. — This order is represented in the Paleozoic 
Rocks by a single aberrant family ; but it is numerously repre- 
sented in the Mesozotc and Kainozoic periods. 

For the Paleozoic Echiiioidea the formation of a separate 
sub-order has been proposed by Professor M'Coy under the 
name of Pertsehoechinidce, since they differ in some funda- 
mental points from all the other known members of the 
order. The test is composed of more than twenty rows of calca- 
reous plates, divided into five ambulacral and five inter-ambu- 
lacral areas. The five ambulacra are continuous from pole to 
pole, and are surmounted dorsally by the ocular plates. TTie 
^ve inter-ambulacra aie combined, each, of three, five, of 




ANNULOIDA ! SCOLECIDA- 



163 



IB0« torn of plAtn, and are surmounted donally by ihe ova- 
rian plates. The two genera Ar(kaMiiinrU and Pa/tafiinus 
com\yniK all the known forms of the family, the former being 
entirely confined to the Carboniferous Limestone, whilst the 
latter occurs also in the Upper Silurians. 

The Secondary and Tertiary M<hin<,^jM resemble those now 
Imng in being composed of not more than twenty rows of 
calesreous jJates. The Oolitic and Cretaceous Rocks are 
Opedally rich in fonns belun^ng to this order, many genera 
bdi^ pectiltar; but tlie number of forms is too great to i>cnnit 
of aaywcledion. 

7. Hoi.OTiiVKOtDCA. — This order, com]>rising, as it does, soft- 
bodied animals, can hardly be said to be knon-n as occurring 
in the fossil condition. Some calcareous plates and spicules, 
supposed to belong to a H<^hurid, have, however, been de- 
scribed as occmriug in the Secondary Rocks, and the shield 
ijt Ps^ux has been found in Post-terliaiy deposits in Bute. 




CHAPTER XXIV. 

SCOLECIDA. 

ScoLEciDA. — ^This class was proposed bjr ProfttMT 
for the reception of the remaining member* of the 
AmntJoidit, comprising the Rotiftra, the TurMiaria, the TWma- 
ttda, the Tamada, the NemaioiJai, the Acini ho<ff hah. and the 
GiiniiMM. Of thew the R^ti/era stand alone, » hilst the Tur- 
kdlarM, TVrmai^la, and 7rf"M</<i<-i>n»titutc the old division of 
llie I'latytlmia (Mai \\'orm\), and the NimalDidea, A<tmtho- 
afk^a, and GerduuM make up the old Nematelmia (Round 
Womu or Thread-worms). I-'or some jiufi^ses these old divi- 
tioiu arc suRkiently convenient to be retained, though they 
are of tiitlc scientilic value. Tlic term Kniestxi has acfiuired 
tud) a General currency that it is necessarily cmplo>-cd occa- 
•iomdlr, but it has been used in such widely diifeccnt senses 
t^ dUlereDt writers, that it would be almost better to discard 
it allf^ther. It certainly cannot be used as s}-nonymous with 
Sttbtida, nuny of these not being parasitic at all. It will, 
thefcforc, be cmpIo)cd here, in a re*lricted sense, to designate 
thoAe orders of the Scolfcidii which are internal parasites, 
comprising ibe Trematoda, Taniada, NtmalaiJia {in part), 
AcvUhac^aki^ and GMiiaaa. The TurUUaria ind Acili/rra, 




r66 MANUAL OF ZOOLOGY. 

with a section of the Nematoidea, lead a free existence, and are 
not parasitic within other animals. 

The Scolecida are defined by the possession of a " water- 
vascular system," consisting of a " remarkable set of vessds 
which communicate with the exterior by one or more aper- 
tures situated upon the surface of the body, and branch out, 
more or less extensively, into its substance."— (Huxley.) No 
proper vascular apparatus is present, and the nervous systein 
(when present) " consists of one or two closely approximated 
ganglia." The habiu and mode of life of the different mem- 
bers of the Scolecida are so different, that no other character, 
save the above, can be predicated which would be common to 
the entire class, and would not be shared by some other allied 
division. 

Division I. Platvelmia. — This section includes those Seeie- 
eida which possess a more or less flattened body, usually some- 
what ovate in shape, and not exhibiting anything like distinct 
segmentation. The division includes two parasitic orders — 
the Taniada and the Tremaioda; and one non-parasitic order 
— viz., the Turhellaria. A sub-order, however, of this last, the 
Nemertida, does not conform to the above definition ; but 
their other characters are such as to forbid their separatioiL 

Order 1. TiEniada (C«/c/i/«i).— This order comprises the 
internal parasites, called Tape-worms (Cestoid worms), and 
the old order of the "Cystic worms" (Cystica); the latter 
being now known to be merely immature forms of the Tape- 
worms. 

In their mature condition, the Taniada {see fig. 48) are 
always found inhabiting the alimentary canal of some warm- 
blooded vertebrate animal ; and they are distinguished by 
their great length, and by being composed of a number trf 
flattened joints or articulations. These joints are not, how- 
ever, an example of true segmentation, nor do they really 
constitute the Tape-worm ; the true animal being found in 
the small, rounded, anterior extremity, the so-called " head," or 
"nurse," whilst the joints are simply hermaphrodite, generative 
segments, which the " head " throws off by a process of gemma- 
tion. The " head " (fig. 48, 3), which constitutes the real Tape- 
worm, is a minute, rounded body, which is furnished with a 
circlet of hooks or suckers, or both, whereby the parasite is 
enabled to maintain its hold upon the mucous membrane of 
the intestines of its host. No digestive organs of any kind are 
present, not even a mouth ; and the nutrition of the animal is 
entirely effected by imbibition. The nervous system consists 
of two small ganglia, which send filaments backwards ; but 




annuloida: scolecida. 



167 



acre is considerable obscurity on this point, and it has been 
a»cncd that the nervous sytilcni is entirely waniing, or that 
there is only a single ganglioD. Tbe " water-vascular system" 
consists of a scries of long vessels which run down each side of 
the body, communicatinf; with one another at each urticula- 
lion by means of a ti-an.tvene ve)>wi, an<l oi^ening in clii: last 
joint into a contnclilc ve^iclo. It tlitts appears that all the 
joints are organicilly cvtine^jtcd together. Whilst the " head '* 
constittilL-s the real animal, il, nevertheless, conutins no repro- 
ductive organs, and these arc developed in the joints or 
segments (fig. 48, 4), which are produced from the head 
posterkuly by budding. Alter the lirst joint, each new seg- 
ment is iDtercaUted between the head and the segment, or 
s^mcnts, already formed ; so that the mints neare« the head 
arc those latest formed, and those furthest from the head are 
the iDoM mature- Each segment, when mature, contains both 
male and female organs of generation, and is, therefore, 
sexually perfect. To such a single segment the tenn "■ pro- 
glottis " is applied, from its resemblance in shape to the tip of 
the tongue. The ovary is a branched tube, whidi occupies 
the greater part of the proglottis, and opens, along with the 
efferent duct of the male organ, at a common papilla, which 
is perforated by an apcri-urc, termed ihc "gcncralive pore." 
The position of this pore varies, being placed in the centre of 
one of the lateral margins of the proglotti.i in the common Tape- 
worm (Tania t^ium), but being situated u]>on the flat surface 
of the t^ment in the rarer BcfhricctphalHs latui. These two 
elements — rtamcly, the minute head, with its booklets and 
suckers, and the aggregate of the joinis, or proglottides— 
together compose what is commonly called a "Tape-worm," 
^■pch as is found in the alimcntar>- canal of man, and of many 
^Pinnals. The lenglli of this composite oiganiana varies from 
a few inches to several yards. 

Singular as is tlie composition of the mature Tape-worn, 
•tiU more extraordinary are the phenomena observed in its 
devdofxnent, of whi<:h the following is a brief account : — 

" I'roglottKJcs," or the scxiully mature scgmcnis of a Ta|>e- 

worm, arc only produced within the alimentary canal of man, 

or of some other waim-bloodcd vertebrate. 'ITie dcvclo|>mcnt 

^^ the ova which are contained in the proglottides, cannot, 

^Btowever, be carried out in tltis utuation ; hence the com[>ani- 

^Vve hannlesxneu of thi.i parasite, and hence the name ot 

" solitary worm," which is toineiiines apjilied to it. For the 

production of an embryo, it is necessarj- that the ovum should 

be swallowed by some animal other than the odc 'inW\nVc&\>i 




l68 MANUAL OF ZOOLOGY. 

the mature Tape-worm. If this does not take place, die fecun- 
dated ovum is absolutely unable to develop itself. To secme 
this, however, the dispersion of the ova is provided for by the 
expulsion of the ripe proglottides from the bowel, all didr 
contained ova having been previously fertilised. Aiter their 
discharge from the body, the proglottides decompose, and Ute 
ova are liberated (fig. 48, i), when they are found to be 
covered by a capsule which protects them from all ordinary 
mechanical, and even chemical, agencies, which might prove 
injurious to them. In this stage, the embryo is often so far 
developed within the ovum that its head may be rect^niscd 
by its possession of three pairs of siliceous booklets. Fot 
further development, it is now necessary that the ovum be 
swallowed by some warm-blooded vertebrate, and should thus 
gain access to its alimentary canal. When this takes place, 
the protective capsule or covering of the microscopically mi- 
nute ovum is ruptured, either mechanically during mastication, 
or chemically by the action of the gastric juice ; and the 
embryo is thus liberated. The liberated embryo is now called 
a " proscolex," and consists of a minute vesicle, which is pro- 
vided with three pairs of siliceous spines, fitted for boring 
through the tissues of its host Armed with these, the pro- 
scolex perforates the wall of the stomach, and may either 
penetrate some contiguous organ, or may gain access to some 
blood-vessel, and be conveyed by the blood to some part of 
the body, the liver being the one most likely. 

Having by one of these methods reached a suitable resting- 
place, the proscolex now proceeds to surround itself with a 
cyst, and to develop a vesicle, containing fluid, from its pos- 
terior extremity, when it is called a " scolex" (fig. 48, 2). In 
some of the Taniada the scolices are called " hydatids," and 
it is these, also, which constituted the old order of the "Cystic 
Worms." When thus encysted within the tissues of an animal, 
the "scolex" consists simply of a tsenioid head, with a circlet 
of booklets and four " oscula " or suckers, united by a con- 
tracted neck to a vesicular body. It contains no reproductive 
organs, or, indeed, organs of any kind, and cannot attain any 
further stage of development, unless it be swallowed and be 
taken for the second time into the alimentary canal of a wainn- 
blooded vertebrate. It may increase, and produce fresh 
scolices, but this takes place simply by a process of gemma- 
tion. In some cases, however, a very partial and limited de- 
velopment does actually lake place in the scolex prior to this 
change of abode, but this is an exceptional occurrence. In 
these cases the " neck" of the scolex becomes partially seg- 



ANNULOIDA : SCXILECIDA. 



169 



nted, so that it comes to resemble an impcrfecrly develoi>ed 
J'ania, and is catkxl a "strobila-embiyo." The series of 
ges, however, mhcrcby the scolcx is converted into Ihe 
'stiobtU," or adult Upc-worni, cannot be c;trncd out unless 
the Molex gain access to the alimentary canal of a warm- 
blooded vertebrate. In this oue, Ihe scolex attaches itself to 
the mucous membrane of the intestinal tutie by menns of its 
cephalic hooklcLs (when these are jiresent) And suckers. The 
latMlal vesicle now drops off, and the scolex is thus converted 
into the " head " of the tape-worm. Gemmation then com- 




|.*Haifllolonr of l^il^ t- Oatfira CItlaiAinff Lha vmhrya in ib IfalbKJT 
• h*aUc«uid«plialiciiKlifni a. AilnRlcfCKivncioini, orpntlaitli. va%- 






. from its posterior cxuemily. the first segments being 
As the first-formed joints, however, are pushed 
fiuther from the head by the constant intercalation of fresh 
articulations, ihcy become .lexually mature, thus constituting 
the " progtottideii " of the adult Tu;>e-wnrm with which the 
cycle beigan. To the entire organism, with its " head" and its 
matUR and immature joinU (" proglottides"), the term "stro- 
bila" i« DOW apfilied. 

In the de^'elopcnent, therefore, of the Tape-worm we have 
to rcroembcT the following sUiges : — 

t. The ^•um, set free from a generative joint, 01 pTO£\QVt\^ 



170 MANUAL OF ZOOLOGY. 

2. The proscolex, or the minute embiyo which is liberated 
from the ovum, when this latter has been swallowed by anj 
warm-blooded vertebrate, 

3. The scolex, or the more advanced, but still sexually im- 
perfect, embryo, into which Hxs proscolex develops, when it hu 
encysted itself within the tissues of its host (Under this head 
come the so-called " Cystic Worms.") 

4. The strobila, or adult Tape-worm, into which the icela 
develops itself, when received into the alimentary canal tA a 
warm-blooded vertebrate. The strobila is constituted by the 
" head," and by a number of immature and mature generative 
segments or joints, termed the "proglottides." 

The subject will, perhaps, be more clearly understood by 
following the development of one of the common Tape-wonns 
of man — viz., the Txnia solium. Commencing with an indivi- 
dual who is already suffering fi-om the presence of this para- 
site, one of the most distressing symptoms of the case is found 
to be the escape of the joints of the animal from the bowel 
These joints are the ripe " proglottides," containing the fecun- 
dated ova. When the ova — which are microscopic in size — 
are liberated by the decomposition of the proglottis, they may 
gain access to water, or be blown about by the wind. In 
many ways, it is easy to understand how one of them may be 
swallowed by a pig. When this occurs, a " proscolex " is libe- 
rated from the ovum, and bores its way through the walls of 
the stomach, to become a " scolex." It now takes up its abode, 
generally in the muscles, in which position it was originally 
described as a cystic worm under the name of Cystuercus allit- 
losa, constituting what is commonly known as die " measles " 
of the pig. In this state the scolex will continue for an in- 
definite period ; but if a portion of " measly " pork be eaten by 
a man, then the scolex will develop itself into a tape-wonn. 
The scolex fixes itself to the mucous membrane of the intes- 
tine, throws off its caudal vesicle, and commences to produce 
" proglottides " instead, becoming, thus, the " strobila " of the 
Tania solium, with which we originally started. The other 
common tape-worm of man — viz., the Tania mediocaneUaia — is 
derived in an exactly similar manner from the " measles " of 
the ox. The young, however, of another of the Tape-wonns of 
man (viz., the Botlirioeephalus latus) is said not to be " cystic." 
In like manner, the tape-worm of the cat (Txnia erassuo/Us) 
is the mature form of the cystic worm of the mouse (Cysliaraa 
fasaolaris) ; the tape-worm of the fox {Tania pisifitrmis) is 
derived from the cystic worms of hares and rabbits {Cysticenus 
pisiformis) ; and the tape-wona of ttie dog (Tania lerratdi is 



^me devclope 



AKNULOIDA : SCOLECIDA. I7I 



' developed fonn of the Cetnnrus etrthraiit of the sheep, (he 
cystic irottn which causes tlie "tuggert " in Ihe lallcr onimaL 

I)e»d<» tapc-womiK, however, man is hable to be iilTct.-tc<l 
with ■' tcolices," which are the larvtc of the tape-worms of other 
animals. Tlius, vhat are profcMJonally called " hydatids " in 
tbc human subject, arc really the scoliccs of the tapc-worai of 
the dog. The disease is iDthcated by the presence of the so. 
called "hydaiid-tuiuour," which consists of a strong meoibran- 
otis cyst — the " hyilaiid " proper — siiiutcd in some solid organ, 
most commonly the liver, and filled with a W3icr>- tluJd. To 
the inleriof of the cj-kI are attached nuinerou.s miiiulc M:oli(:e3, 
many otltert aUo Boating freely in the contained titiid. 'I'hcsc 
" Ediinococd," u they are called, do not ditfer in structure 
fiom other icolices, consisling of a head, i^ovidcd with four 
suckers and a circlet of recurved hooklcts, a vesicular body, 
and an inicrmediale comnicled portion or neck. The Echi- 
Dococci multiply within tlie hydatid cyst by (;cmmaiion, but 
they develop ivo reproductive oncans. If, however, an Echi- 
Doooccus should gain access to the alimentary canal of a dog, 
it then becomes lite tape-womi peculiar to that animal — the 
itCHM tthisucftiiu. 



CHAPTER XXV. 

TREMATODA AND TURBELLARIA. 

IDER Trematoda. — This order includes a group of animals, 
like the {Heccding, arc parasitic, and arc commonly 
1 OS " suclorul worms," or " Flukes." Tlicy inhabit van- 
ntuationa in diGTereni animals — mosUy in birds and fishes 
', they are usually flailciied or roundish in sliajie. The 
I provided with one or more suctorial pores for adhenion. 
linal canal, with one exception, is always present, hut 
this is simply hollowed out of the substance of the body, and 
docs not lie in a free space, or " perivisceral cavity." The 
intcstiiul canal is often much branctied. and possesses but a 
^hcle external opening, which serves alike as an oral and an 
HnU aperture, atiia is usually placed at the bottom of an an- 
terior tiictorial disc Tlie sexes are united in tlie some indi- 
jddnal. A " watcrvascular syntcin " is always present, and b 
^Enctimes " divided into two portions, one with contractile and 
^ta-ciliated w^ls, the other with non -contract tie and ciliated 
waDs."— <HuxIcy.> 




172 



MANUAL OF ZOOLOGY. 



The Trematode Worms are all hermaphrodite, and they pan 
through a series of changes in theii development somewhat 
analogous to those observed in the Taniada. This subject, 
however, is still involved in great obscurity, and it is too coo- 
plicated to admit of description in this place. The laivB arc 
often tailed, but never possess cephalic booklets, and are ners 
" cystic." 

From the absence of a perivisceral cavity, the lyanateda 
were fonned by Cuvier into a separate division of Entotca, un- 
der the name of Vers fnUsHnaux paraukymatmx, along with 
the Taniada and Acantkocephala, in which no alimentary canal 
is present By Owen, for the same reason, they are included 
in a distinct class, under the name of SUrdmMha. 

The Distgma kepatiaim (fig. 49) may be taken as the type of 
the Tremaioda. It is the common " Liver-fluke " of the sheep, 





Fij. 49.^Trematoda. i-^«/tfii«i/>*/Kiir<i*,lhc"lJver-flulfc."i>iowui(lheln»Bdbrf 
aiAOixnOn aaaX. 7. Anterior cktrtmity of Diiiema lameeLttuit. m ADtcnoi 
(uckcr; ^PotlcHor luclLcr; cGeaeraiive pon; ^<Ewphagus; r AJinwDUry cabaL 
(After Owen.) 

and inhabits the gall-bladder or biliary ducts, giving rise to the 
disease known as the "roL" In form it is ovate, and flattened 
on its two sides, and it presents two suctorial discs, the ante- 
rior of which is perforated by the aperture of the mouth, whilst 
the posterior is impervious. Between the suckers is the 
" genital pore," at which the efferent ducts of the reproductive 
organs open on the exterior. A branched water -vascular 
system is present, and opens posteriori/ by a small aperture. 
The alimentary canal bifurcates shortly behind the mouth, the 
two divisions thus produced giving off numerous lateral diver- 
ticula, and terminating posteriorly in blind extremities. The 
nervous system consists of a ring round the gullet, giving off 
filaments both forwards and backwards. The \an^ ^ DisUma 
are tailed or " cercaiiform,",and are found in the interior of 
fi'esh-water snails. 




annuloida: scolecida. 



173 



■Mm 



In Disi&ma la$umlatMm (fif;. 49, 3) the intesiine lias not the 
lose, complex diameter of that of D. hepatkum. On tlie 
other hand, the aliinent:iT)' dtiat, after its liiftircation, is con- 
tinued on each side of the body to the ponterior extremity 
ithotit giving olT nny branches on the way, and it tcrmioates 

ply in blind extremities. 
I>ifiast»mim, in its essential characters, docs not difter 
much frocn Duioma; but il is found living greg'^riously in the 
vitreous humour and lens of the eyes of certain fire^-water 
firiics, such as the common Perch. 

Other members of the order infest tlie intestines of blnU and 
BatnchioRS, the gilU of Ashes, or the jmuneh of Rumiiuuits. 

Okdkr Ti;itniai.AitiA. -- 'llie members of this order arc 
almost all aquatic, and nre all non-parasitic; thus difTering 
entirely from the animals which compose the two preceding 
orders. Their external surfaee is alw.iys and permanently cili- 
ated, aivd they never possess cither suctori^ discs or a circlet 
of ce|>halic booklets. A " naccr- vascular sysiciD " is always 
present, opening externally hy one or more apertures, or a)»- 
jicarinf; to be entirely cloned in the adult (Nemerlsda). As in 
the Irtmah-Ja, (he alimentary canal is imbedded in the ]»ren- 
chyma of the body, and, except in the Nfm/rtiJa, there is 
DO "peiivisceral cavity." The intestine is either straight or 
branched, and a distinct anal aperture may. or may not, be 
present Tlte nervous system consists of ganglia situated in 
the fore-part of the bo<ly, united to one another by transverse 
cords, and semling filaments backwactU. 

The TurMlaria .arc divided into two sections, tenned re- 
spcclivcly the I^anarida and the .\'emfTtiJa. 

SUB-OKDKK I. rLANAttiUA.~'rhe I'lnn.irians (fig. 50) are 
tly ovoid or elliptical in sh.ipe, tiatlencd, an<l soft-bodied. 
icy arc for tlie most part aqu.itic in their habits, occuning 
fresh water, or on the sea-shore, but occtstonally found in 
earth. The inicKumenI is abundantly provided with 
c cilia, wlii< h sul>serv*e locomotion, and il also contains 
us celU wliirh have been compared to the '*cnid»,'* or 
tllle-cclls, of Ihc OtlaHtrala, Tlterc i.i always a considerable 
a of the body situated in front of the mouth, constituting 
K>-called "pnc-oial region," or " prostoroium " ; and this is 
en modified into 3 angular protnisible and retractile organ, 
called the " proboscis," the exact use of which u not known. 
The mouth opens into a muscuUr pharynx, which is often evert- 
ible; and tlic intestine may be cither straight or branched, 
but alwajrs termiitaies cxcally behind, and is never provided 
with an anal aperture The " iralcr-vnsculai synMnv" commtt 





174 



MANUAL OF ZOOLOGY. 



nicates with the exterior by two or more contractile apertures. 
The nervous system consists of two ganglia, situated in finml 
of the mouth, united by a commissure, and giving ofThlamcnti 
in various directions. Figment-spots, or rudimentaiy eyes, 
from two to sixteen in number, are often present, and are il- 
ways placed in the pne-ora! region of the body. The male and 
female organs are united in the same individual, and the pro- 
cess of reproduction may be either sexual, by means of true 
ova, or non-sexual, by internal gemmation or transverse fission. 





^«r SO — Morphology of Turbellaru, t. Planjtria forva (Muller); m IhrouUll r 
Nerve-Eaneltnn ; ^ Ey«; ffrOvary; / Tc«li*i ; fv GenLul f>pciun£. a. Piamant 
bKtra, ihowLnK rhv brahchvd (dcndroccel) inteiimc. 3 M^cr»co|Hc Urva f^Aiamr- 
iita. a nuinnc Turbttlariaiir 4. PHiitium. tht '^pwdcmbryo** of ■ Neavrtid; 
d '.The alinwntary taoaj; b RudiiDCnl of the Nememd- 

The Pianarians have been divided into two sections, as 
follows : — 

, Stction A. Rhabdoc(ELA. — Intestine straight, not brandhed. 
Body elongated, rounded, or oval. 

Section^. Dendroc(£la. — Intestine branched or arborescent 
Body flat and broad. 

Sub-order II. Nemertida. — The Nemertida, qx "Ribbon- 
worms," agree in most essential respects with the Planarida. 
They are distinguished, how■e^■er, by their elongated, vermi- 
form shape, by the presence of a distinct anus, by the posses- 
sion of a distinct perivisceral cavity, by the absence of an 
external aperture to the water- vascular system of the adult, 
and by the fact that the sexes, with one or two exceptions, arc 
distinct The Nemertida further differ from the other Flaiytt- 
mia in possessing a pseudoh.Tmal system in addition to, and 
distinct from, the water-vascular system. 

Reproduction takes place by the formation of true ova, by 
internal gemmation, or by transverse fission. In Nenurta, 
bowera, the egg gives rise to a Urva, from which the adult is 



I^loped in 



ANNULOIDA: SCOLECIDA. 17$ 



eloped in » mamncr closely on^logouG to that described as 
diaraclcristic of ihc iUAiiuJtrmata. The larval fonn of A^e- 
mfrta was described by Johannes Miillci, under the name of 
Pilidium (6k. 50, 4). It is "a small hcmct-shiiped larva, with 
» long ftagelluro attadicd like a plumello the summit of the 
helmet, the tA^tA and side-lobes of whidi arc richly ciliated. 
A simple alinventary canal oijchk upon the under surface of 
the body between the lobes. In this condition the larvz 
■wuns about freely \ but. after n while, a nuss of formative 
matter appcata on one side of the alimentary canal, and, elon- 
gxdng gradually, takes on a worm-like figure. Eventually it 
grows round the atimcnury canal, and. appropriating it, de- 
taciKs itself from the PiMium as a Ncmerlid— provided with 
the characteristic proboKis, and the otlier organs of tliat group 
of 7i«rf«iterw.'—< Husky.) 




CHAPTER XXVI. 
NEMATEIMIA. 

ACAKTHOCEPHALA. 2, GoRDtACKA. 3, NeMATODA. 

Division [I. Nfjiatelmia. — This section maybe considered 
as comprising those Scolecids in which the body has an elon- 
gated and cylindrical shape. Stricdy speaking, it should 
include the Nnturiida, but the division it not founded upon 
anatomical duiaclers, and if cmjiloyed here simply for con- 
Tcnkncc. Klost of the A'tmalflmia possess an annuUted tn- 
tegument ; but there is no true segmentation, and there arc 
lardy any locomotive appendages attached to the body. The 
majority are unisexual, and pomsiiic during the whole or 
a part of their existence. Three orders are cumprihed in 
this divnioo — viz., the Aianthoaphala, the G^diacea, and the 
Ntmateda. 

Okukr I, AcAjmiocKPiiALA. — The AcaHlhMffrhata are en- 
tirely puirssiiic, vermifonn in shape, and devoid of any month 
or alimentary canaL Tliey ore provided with n kind of snout 
or prabo&cis armed with recurved hooks, which is continued 
tuocwards into a bandlikc structure (Ugamtnlum stupentariHmY 
to which the reproductive organs are attached. " Immediately 
beneath the integument lies a series of reiiculalcd canals con* 
tainng a dear Oaid, and it is diJKciUl to see w\th w\ut. Vhcw 




176 



MANUAL OF ZOOLOGY. 



can correspond if not with some modification of the water- 
vascular system."— (Huxley.) This system of vater-vasoilir 
canals, however, does not communicate, so far as is known, 
in any way with the exterior. At the base of the probosdl 
is placed a single nervous ganglion, which gives off Fadiating 
filaments in all directions. 

Besides the presence of a water-vascular system and the 
absence of any alimentary canal, another point of affinity 
between the Acanthocephala and the Taniada has recently 
been established by the discovery that the adult wonn is 
developed within a hooked embryo, from which it is se- 
condarily produced. 

The "Thom-headed worms" include some of the inoit 
formidable parasites with which we are acquainted. The 
Echinorkynchus (fig. 51) is found in the intestinal canal of 
many vertebrate animals, especially of birds and fishes. 

Order II. Gordiacea. — The Gordiaeta, 
or " Hair-worms," are thread-like parasites, 
which in the earlier staged of their existence 
inhabit the bodies of various insects, chiefly 
of beetles and grasshoppers. They possess 
a mouth and alimentary canal, but they are 
not provided with a disrinct anal aperture. 
In Gordius itself the gullet is said to open 
directly into the body-cavity ; but it is more 
probable that this is an error, and that 
there is a complete intestine opening pos- 
teriorly into a cloaca. The sexes are dis- 
tinct, and they leave the bodies of the in- 
sects which they infest in order to breed ; 
subsequently depositing their ova in long 
chains, either in water or in some moist 
situation. At the time of its migration the 
mouth of the adult Gordius appears to be 
obliterated, and the anterior portion of the 
alimentary canal becomes atrophied. 
In form the Gordiacea are singularly like hairs, and they 
often attain a length many times greater than that of the insect 
which harbours them. 

Order III. Nematoda (or Nemaloidea). — The Nemateda — 
" Thread- worms " or "Round-worms" — are of an elongated 
and cylindrical shape; and are often, though by no means 
always, parasitic in the interior of Other animals. They possess 
a distinct mouth and an alimentary canal which is freely sus- 
pended in an abdominal cavity, and terminates posteriorly in a 




F"S' 5"' — Acanlhoce- 
sire ; tt' The hnd of 



phab 

Lhc Mme magnified. 



Ectiiiter- 




AHNULOIDA: SCOLECIDA. 



ftDQi. They also possess a system of canals, in some 
iMitnctile, which open exti:n)all)r near the anterior part 
ftody, on the ventral surface, or \>y lateral pom, 2nd arc 
hr nomoloigous with the water- vascular sj'stcin of the 
u and T^ntateda. Tlie texu^t arc distinct, and ihc 
^n usually less fTcmicnily ni<;t with, and of smaller 
■an the feinales. The nervous sjrstcm is mostly well 
^ed, and is in the form of a ganglionic ring, sunound- 
kcesophagus, and sending Glamcnis backwards. 
Cfore said, most of the Nemal^a 31c internal [laraiiies, 
fes the alimentary canal, the pulmotary tubes, or the 
I tissue, in man and in many other vertebrate animals ; 
trgc section of the order are of a permanently free habit 
encc. 

most familiar examples of the 
jc Ntmatoda arc the Asairis 
MSef, the little Oxyuris, the 
If, and the Guinea- worm. 
\Astaru fumbriatdes, or cotn- 
Krand-worm, inhabits the inlcs- 
|inao, often nltaimng a length 
iral inches. The ova arc iffo- 
spelled with the fa»:es, and 
jbryo is developed within the 
|mor to its rupture. When 
tnned, the embryo is about 
idrcdth of an inch in length, 

dcvelopRKnt is not exactly 

though it appears to be di- 

insfcrrcd from river or pond 

the alimentary canal of >otne 
,tc animal. 
Oxyurh tftrmieuiarU, or 

Thread - worm," is a gre- 

worm, which inhabits the 

espc«:):illy of children. It 

smallest of the intestinal 

of RUD, its average length 
ing more than a ((uarter of 
p, but the females are much 
than the males. 
Truhina tpiratis is a singular 
id. which gives rise to a |Miin- 

very generally fatal train of symptoms, somewhat re- 
ig rheumatic ievcr, and known as I'lichiniasi^. TVic 




ri( f) — Kdfwcudii, h Anpr- 




178 MANUAL OF ZOOLOGY. 

Trichina is known in two difTcrent conditions, sexually inmiti' 
ture or mature. In its sexually immature condition it inhalnti 
the muscles, usually of the pig, in vast numbers, each wonn 
being coiled up in a little capsule or cyst. In this condition 
the worm is incapable of further development, and may re- 
main, apparently for an indefinite period, without change, 
and without seeming to produce an^ injurious results to die 
animal affected. If, however, a portion of trichinatouB musde 
be eaten by a wami-blooded vertebrate, and so introduced into 
the alimentary canal, an immediate development of yotmg 
TYichiniE is the result. The immature worms escape &an 
their enveloping cysts, grow larger, develop sexual organs 
and give birth to numerous progeny, which they produce 
viviparously. The young Trichina thus produced perfoialc 
the walls of the alimentary canal, and, after working their 
way amongst the muscles, become encysted. If the animal 
in which these changes go on has sufficient vitality to bear 
up under the severe symptoms which are produced by the 
migration of the Trichinm, he is now safe ; since they can- 
not become sexually mature, or develop themselves further, 
until again transferred to the alimentary canal of some other 
animal. 

The Guinea-worm {Dracuruu/us or Ftlaria medinauis) is 
a Nematode worm, which inhabits, during one stage of its 
existence, the cellular tissue of the human body, generally 
attacking the legs, and often atuining a length of several feeL 
All known specimens of this parasite are impregnated females, 
containing a large number of young. The worm remains im- 
bedded in the body, in a more or less quiescent condition, for 
a year or more, at the end of which time it seeks the surface, 
in order to get rid of its young. No external aperture to the 
genital organs has hitherto been proved to exist, and it seems 
possible that the young are produced within the body of the 
parent by a process of internal gemmation. The young FUari^ 
consists of a vermiform body, terminating in a hair-like tail; 
and when set free from the parent, its further development 
probably takes place in water, when it is believed to be con- 
verted into one of the "Tank-worms " so common in India. In 
this condition it is possible, as some believe, that sexual organs 
are developed, and that the females are impregnated. The 
worm is believed to gain access to the body of bathers, when 
still extremely minute. According to Dr Bastian, however, it 
appears probable that the Guinea-worm " is a parasite only 
accidentally, and that it and its parents were originally frM 
Nematoids." 




ANNUtOIDA : ROTIFERA. 



"79 



The second acctwn of ihe NawUeda com prises womii, which 
arc not ut xny liine |ianu(itic, but which are penoanently free 
Theae "free Nematoids" (fig. s») tonsiimtc rhc family of the 
AHgmiHuiubt, of whidi about tvro htindicd sj>ci;ics have bccD 
already described, mostly inhabiting fresh water or the shores 
of ihc tea. llKy resemble the parasitic Nematoids in all the 
c«Kntial features of iheir anatomy, but ihcy differ in often 
possessing pigment-spots, or rudiinentar>- eyes, in being mostly 
provided witli a lenninal sucker, and in bringing fortli conv 
poratively few ma at a time ; tlie <lunger> to whidi the young 
are exposed being much len than in the panuilic formn. 
Amonf^st tlie more familiar Neraatoi<lE are the Vinegar Eel 
(AMgttttlula aceti, fig. 53, A) and the lyiaxfiiu (or Viirie) 
IritUi, whicJi produces a sort of excrescence or gall upon 
the cor of wheat, causing the disease known to farmers as 
ti»e " Poipka," or " Ear Cockle." 

Hm paiwtic and free Ncmaloids are connected togetliei by 
aa Amrii (A. nigrvt'e»»sa\, which in succeeding generalions is 
alternately free and paTasitic This Astaris has long been 
known ax inhabiilng the liiTigt of the frog, but it has been 
Uiown by Mcrinikow that " the young of this animal become 
real, free Nematoids ; for, after passing from the intestine of 
the (rog into damp earth or mud, (hey grow rapidly, and 
actually develop in the course of a few days, whilst still in this 
catenud medium, into sexually mature animals. Young, differ- 
ing aoRiewhat in extental diaiacters from their parents, are 
•om ptoduced by them, and these attain merely a certain 
stage of devetoptncnt whilM in the moixl earth, arriving at 
sczoal maturity only after they have become |Mra.iiie:(, ;u>d are 
coaoooced in the lung of the frog." — (Bastian.) This cxtraor- 
diftary history is rendered still more remarkable, if i[ should 
be proved that Ihc young of Ihc parasitic forms oi this Asiaris 
are pfodiMrcd by a proceas of paithcnogencMs ; and this seems 
to be highly probable, since none of Ihc individuals which are 
found as piarasiles are males, but are universally females. 




CHAPTER XXVri. 



ROTIFERA. 

Sd»«lass RoTiniRA {Rit/atoria). — The Sati/tra, or " Whe«V 
anunalculcs," coostitutca vci^' oaiuniJ group, ^e ciuuJl posiuo'Ci 



l80 MANUAL OP ZOOLOGY. 

of which has been a good deal disputed, and is st31 donbtM. 
They are looked upon here as a distinct division of the Sak- 
atfa, following Huxley ; but they are very frequently placed 
with the Annelida amongst the lower division of the Ama^Kt 
(Anarlhropodd). "" 

The Rotifera are Annuloida of a mintite site, never para^, 
inkabiiing "water, and usually provided with an anterior ciliated 
disc, capable of inversion and eversion. In the femaUs there is 
a distinct mouth, intestinal canal, and anus. A nervous sy^em 
is also present, consisting of ^nglia, silvaled near the anterior 
extremity of the body, and sending fUaments backwards. A voter- 
vascular system is also present. 

Most of the Rotifera are entirety invisible to the naked 
eye, and they are all extremely minute, none of them attain- 
ing a greater length than i-36th of an inch. Nevertheless 
as remarked by Mr Gosse, " so elegant are their ontUneSf 
so brilliantly translucent their texture, so complex and yet so 
patent their organisation, so curious their locomotive wheels, so 
unique their apparatus for mastication, so graceAil, so vigorous, 
so fleet, and so marked with apparent intelligence their move- 
ments, so various their forms and types of structure," that they 
fonn one of the most interesting departments of zoological and 
microscopical study. They are all aquatic in their habits, and 
in the great majority of cases are free-swimming animals, some, 
however, being permanently fixed, as is the case with Stephant- 
ceros, Melicerta (fig. S3. B). and Floscularia. 'ITiey arc usually 
simple, but are occasionally composite, forming colonies, as in 
Megalotrocka. As a rule, the male and female Rotifera differ 
greatly from one another, the males being smaller than the 
females, destitute of any masticatoiy or digestive appaiatas, 
and more or less closely resembling the young form of the 
species. The most characteristic organ in the great majority 
of the Rotifera is the so-called "wheel-organ," or "trochal 
disc," which is always situated at the cephalic or distal end 
of the body, and consists of a retractile disc surrounded by a 
circlet of cilia, which, when in action, vibrate so rapidly as to 
produce the illusory impression that the entire disc is rotating. 
The disc, which carries the cilia, is capable of eversion and 
inversion, and may be circular, reniform, bilobed, four4obed, 
or divided into several lobes. It serves the purpose of loco- 
motion in the free-swimming forms, acting somewhat like the 
propeller of a screw-steamer, and in all it serves to produce 
currents in the water, which convey the food to the mouth. 

In Chatoneius, and one or two other forms, there is no true 
wheel-organ, capable ot praUus^oYi axid.t%txaction, but the cilia 



ANNULOIDA: ROTIFERA. 



181 



«« mi(ns}y disposird o%-cr lh« suiiac« of the body. The 
Qb rt ww ft' or Haiiy-txickcd Animalcules have no jiirx, and have 
the ventnt surface of the body clothcfl with <'ilia. 'Iliey hsvc 
Dfually been placed in ilic TurMlaria, but there »cem Ki tie 
good reuoas for reganling thccn as an aberrant giou[> of Rota- 
toria. 

The |]TOxbnal oUremity of the body in the free forms tcr- 
minates in a caudal process, or " foot," sometimes telescopic, 
which ends in a suaorial disc, or in a poir of diverging " iocs," 
which act as a pair of forceps (lig. 53, a). 





mtm ril«ili»iil} « llnmwtin In iht (llliM4 dlv 1»i1in| in Ihc dicouic mul 1 4 
Mi«lfr> e PhvTVcnl Httr 01 muUi. wiLh th? jndkEicdUry Jpr«nr<i4. ^SltiQiMD; 

mafgiam O'JH. tliif «> tUUM<t pit (*)i f Uvary. R .Vriiirrta nVu- (Afbor 

The month usually opens into a phar^-nx, or " buccj] funnel," 
which is generally provided with a musrubr coat, consliliiling 
the " nu&tax ' or " phjryngeal bulb," nnd which generally eon- 
tjunt a wry coniplicited masticatory apparatus.* '["he parts 
ot this .ip|)antux are homy, and arc believed by Mr Oosse 
to be hoRiologou* with the partS'of the mouth in Insects. 
Id the fenulcs of lUmrat all known species of Hotiftra the 
JH^fufpifl canal ii a iDOrc or leu simple tube, extending 

* Tbc tower jawi, or "incut," coiuitt ofa Axed portion, the "fulcrum," 
to whidi ir« aliachid two moiablc bU(!«»— ihe " romL" The iii)p« jaiw, 
or"Buliei,"oaiH>«l<acliofahan(Il«, or "In•nnl^r{aIn,'' to whicbahinscd 
■ looihcd blade, M'' 



i82 MANUAL OF ZOOLOGY. 

through a well-developed perivisceral cavity, and temunat- 
ing posteriorly in a dilatation, or "cloaca," which fonni the 
common outlet for the digestive, geaerative, and water-vasculsr 
systems. 

In both sexes there is a well-developed water-vascular sys- 
tem, usually consisting of the following parts : — In the hisdcr 
part of the body, close to the cloaca, and openii^ into it, is > 
sac or vesicle, which is termed the " contractile bladder," and 
exhibits rhythmical contractions and dilatations. From the 
contractile bladder proceed two tubes — " the respiratmy tubes" 
— which pass forwards along the sides of the body, and ter- 
minate anteriorly in a manner not quite ascertained. Attached 
to the sides of the respiratory tubes, in all the larger Rotifera, 
is a series of ovate or pyriform vesicles, each of which is fiir- 
nished internally with a single central cilium, which is fixed to 
the free end of the vesicle. It is asserted, however, that these 
ciliated vesicles communicate internally with the perivisceral 
cavity with its contained corpusculated fluid. The exact fiinc- 
tion of this water- vascular system is not known, but it is most 
probably respiratory and excretory. Dr Leydig believes that 
water enters the perivisceral cavity by endosmose, where it 
mingles with the absorbed products of digestion, to form the 
so-called " chylaqueous fluid " ; and that the effete fluid is 
excreted by the respiratory tubes, and ultimately discharged 
into the cloaca by the contractile bladder. Taking this view 
of the subject, Mr Gosse believes that " the respiratory tubes 
represent the kidneys, and that the bladder is a true urinary 
bladder " ; and consequently that " the respiratory and urinary 
functions are in the closest relation with one anodier." This 
observer, further, finds a decided analogy between the above 
system in the Rotifera and the long and tortuous renal tubes 
of the Insecta, to which class he believes the Rotifera to be 
most nearly allied. No central organ of the circulation w 
heart and no organs of respiration are present, but the perivis- 
ceral cavity is filled with a corpusculated fluid. 

The nervous system of the Rotifera constitutes a bilobate 
cerebral mass, "which for its proportionate volume may com- 
pare with the brain of the highest vertebrates," It is placed 
anteriorly, and usually on the dorsal aspect of the body, and 
the eye — in the shape of a red pigment spot or spots — 
is invariably situated like a wart upon it Other sense- 
organs, probably tactile, are often present in the form of 
two knobs surmounted by tufts or bristles, placed at the back 
of the head. The ovaries constitute conspicuous organs in 
the female Rotifera, but in summer the young Rotifers appear 





AKNULOIDA: ROTirERA. 



183 



cA hy the femates without haWng access to (he 

mutcular sjrstem of the RMifera U well developed, con- 
ng of bands which ]>roducc the various movements of the 
f and foot, whilsi others act upon the various viscera, and 
n dlcct the movements of the j.tws. 

l>e typical group of the Rodjtra is that of the Notommalina 
•datinta of Ehienberg). In this group the animals arc all 
nonenily free, und are never combined into colonics, while 
interment is flexible, and the body is never encased in a 

tffhano^rvt and l^Motlaria, on the other hand, are fixed, 
encloccd in a gelatinous tube which is .iccrctcd l>y the 
MHuetia (li^. 33, B) inhabits a tubular c^se, which 
inuO fonns for itself by means of a special organ for the 
whilst Polyarthra and Triartira arc protected by a 
icll. or " lorica." 
ii 7Viar1l>ra there arc twelve ensiform fins, jointed to the 
J by distinct shelly tubercles, and moved by ])owcrful 
cles. These nnutory organs are considered by Mr Gosse 
M homologous with the articulated limbs of the ArtMtv- 



\ 




Ai^nthta, whilst the masticatory organs, gullet, and 
Mch a« well developed, there is no inicsiinc, the stomach 
like a globe in the centre of the bodj-Kavily," but not 
ting with the body-cavity. 

Es or RoTiFERA. — In their external appearance the 
iffra aj>pr<)ximate closely to the Infusoria, but the ui;j;anisa- 
o( the former presents a verj- striliin^ advance when cora- 
rd with that of the latter. 1 hus, in the fn/ntoria there is 
dificrcntiated bo(ly<avity, bounded by distinct walls, and 
UitneataiT canal is imfkcrfccl, the digestive sac simply 
mng infcriorly into the diffluent sarcode of the centre of 
liody. Furtlicr, there arc no traces of a nervous system, 
~ ' e contractile vesicles, if looked upon as reiiresenting the 
vascular S)-kieni, are a very nidinieniary funn of this 
tus. In the Reli/rm, on the other hand, the alimentary 
forms a complete tube, having an oral and an anal aper- 
and not communicating with the surrounding perimccral 
; and there is a well -developed nervous sytiicm, and a 
complex water-vascular system. A real affinity is found 
isisi, however, between the Roti/era and the P/anarida; 
posscssitig external cilia, a nervous system, and a well- 
' w«ter>rascu]ar apparatus, the characters of which are 
Has in the two groups. In the Fianarida^ \xfit- 




1 84 



MANUAL OF ZOOUXST. 



ever, the sexes are united in the same individual, and tlure if 
no anal apeiture ; whereas in the Heiifera the sexes are du- 
tinct, and there is a distinct anus. To the true Arikrt^oia, u 
already pointed out, the Jtoti/era shows some points of affim^, 
but these are hardly sufhcietitly numerous or decided to war- 
rant the removal of the group from the Atmuioida to the 
Annuiosa, 



185 



ANNUL OS A. 



CHAPTER XXVIII. 

ANNUU>SA. 

I. Grkbral Chaxactsiis or Annulosa. i. Gbnbral 

ChaRACTKRS of ANARTIIKOI-UtiA. J, Cl.ASS GePHVREA. 

4. Gekkral Chakacteks ok the Class Ann(;ui>a. 

Si«-itiNCDO« AUNULOSA.— The members of ihis sub-kingdom 
are dtsdnguishod by (he possession of a My whUh is eamposed 
^ Humtrgus teguKiUs, sr " somilet" arriinfeJ a/tmj; a hngittUittai 
axis. Anmrnit tyitetHtsiihtiiys frtsfnl,and<emitli o/ad^ubie 
(Aain of ganglia, rmining along lfi( ^mlnjl sur/atf 0/ the body, 
anJ troitrsed anitriorty by t/it eciofkagus (fig, 54). T/if limbs 
{when frtttMt) art tuntai t(ytthndt the natral atpett of tht body. 

TIk tub-kingdom Annuhta may be divided into two primary 
divisions, according as tlic body is (irovidcd wilh aniculated 
appendages, or out; these divLsions being termed respectively 





i rH(*(il<>t p)pMm ; t KcHnl iirH«n. 

d»e AHhnfoila and Anarihropeda. The fim of these com* 
prrae& Crustaceani, Spidery Scor|iton!i, Ceiilipedei;, and Insects ; 
whibt the latter inchidcs the Spoon-worms, X^ceches, Earth* 
worm!), Tulw-ironns, an<l Sand-worms. 

Division I. ANAHTiiRoronA. — In this divisionof the/firjTtf' 
Uia Ihf heaMelht afperula^s art iKitr distinttly Jointtii or arti- 
tuialid fc Ihf body. In this division aic included three classes, 
yit r — the GtfAyrea, the Anndida, and the Chaio^atha. 

Class I. Gbphvrka ( = A/wwcw/Wnr).— This class includes 
cenaia worm-like aaimus in which the body is sotuecimes ob- 




■86 



MANUAL OF ZOOLOGY. 



viotisI]r annulatcd, sooMtimes not ; but |]ia-e are no ambtdaoat ] 
tube* nor foot-tubercles, though thirrc are tometimo bristln ' 
concerned tn locomotion. The nervous t)-stcm consi&is of an 
oesophageal nerve-collai- and a cord placed along the ventnJ 
sutOcc of ihc l>o<ljf. 

The SiJUtnai/ut and its allies (fig. 55) malct up this cU«, 
aod from their affinity to the ironn4ilie Holotburians the)- have 
often been placed amongst tlic BiAinfu/^mata. They arc not, 
however, provided with an ambubcnd ^yxtem, the integument 
is not capable of secretiitg calcareous matter, and there are no 
traces of any radiate arranf(ement of the ner^-ous qrstctn. 

The Si^uit^lut is a worm which ts found burrowing in the 
sand of the coxiLt of mosi of our European sca^ or which in- 
habits the cast-away shells of dead univalve Molluscs. The 
different species differ much in length, varj-ing from half an 
inch to a fool or more- The body is cylindrical, covered by t 
delicate cuticle, beneath which is a thick, muscular, and highlf 




Fia< u-— Cciilqr'V- 



>«(Mt. The anterior portion of the body fonns a 
t''tnaft or proboscis, at the extremity of which is the 
mouth surrounded by a circlet of simple tentacles, llie ali- 
mCDtar}' canal is proportionately of great length, and is much 
convoluted. Ujion reaching the posterior extremity of the 
body it is reflected fom-aids, and it terminates in a distinct 
anus, which is placed anteriorly near the junction of the l>ody 
with the proboscis. The sexes are distinct in all the Gt^yrea, 
unil the youiif; pass through a metamorphosis. 

[n Ethiurus, nhich is mund on the coasts of the North Sea, 
the body is provided posteriorly with zones of homy bristles ; 
and in the Sternas^ of the Adriitic similar xoncs of bristles 
arc found anteriorly as well as posteriorly. In the IifAiur>4a, 
also, there arc brancli<:d tubes connected with the tcnninaiion 
of the intestine, which arc doubtless homologous with ihc 
'• respiratoiy tree" of the HolothurliLns. In Bonellia there n a 
proboscis formed by a folded Beshy plate, susceptible of great 




ANNULOSA : ANNELIDA. 



tSj 



'elonpihon, nnd forked al its extremity. The vent is at the 
Dt>j>o!iilv end o( the body, and the inlcsttnc U very long, aud 
toUieii scrend lines. 

The British species of the class are grouped by Profe&sor E. 
Forbes as follows : — 

/uuv. I. Sffiitneu/acea, having a retractile [irobosciK, at the 
bate of which ihv anu.i ih placc<j, and round the extremity of 
which is seen a rirclet of IcntAclcs. 

Aim. II, Priapuiafea, having a retractile proboscis but no 
IcntAcula, and having the anus placed at the extrcmily of a 
fittfoRn, caudal appendage. 

A«r. III. Thaiastfmacta, having a proboscis to which a long 
ajipeiidage is attached, lliere are no oral tcntacula, and 
tnns IK ]>l.iced at the posterior extremity of the body. 

CutSS II. .\siit.UDA. { - Annuiata). — The Annelida nrc dis- 
ingtiishcd fvxa the preceding by the possession of distinct 

temal segmentation ^ the nervous system i§ composed of a 
ventral, double, gangliated cord, with an oesophageal collar 
and prac'CEsofiha^al g«ii(^ion. 

This class comprises elongated, wonn-likc animals, in which 
the integument !.■> always soft, and the tioily '» more or less 
distiactly segmented, each segment lutully cones jionding with 
a sn^le pair of gangli.^ in the ventriii coid. All the segments 
are similar to one another except those al the anterior and 
posterior extremities of the body. I^ch segment may also be 
provided with a pair of lateral appendages, but these arc never 
ariicuUted to the body, and are never so modified in the region 
of the head as to be converted into masiicalory otgans. 

In the higher .rfis*/*!*!* each segment (fig. 56)eonsi»uort«-o 






n*. ]ft— DbcfMMiMk truMTtrM Wfifnii 4r an Annilld*. VDoiul an; r Vcnm 
I ME* UM 1 rsiBMd cinhu. 

ics, wmwil, from their position, respectively the " dorsal 
~ aiod the " vential arc " ; and cadi bears two lateral pro- 




l88 MANUAL OF ZOOLOGY. 

cesses, or "foot-tiibercles" {parapodia), one on each side. 
Each " foot-tubercle " is double, being composed of an appa 
process, called the "notopodium," or "dorsal oar," and a lower 
process, tenned the " neuropodium," or "ventral oar." The 
foot-tubercles, likewise, support bristles, or " setse," and a icft, 
cylindrical appendage, which is tenned the " dirhus " (fig. 56). 

The number of the segments varies much, being as many as 
400 in Eunice giganlea; and, generally, there is not a. disdnct 
head which is separable from the succeeding rings of the body. 
When such a distinct head appears to be present, it is not com- 
parable with the head of the Arthropoda, but is really a greatly 
modified pras-oral region, or " prostomium," as is shown l^ 
the position of the mouth. 

The digestive system of the Annelides consists of a mouth, 
sometimes armed with homy jaws, a gullet, stomach, intestine, 
and a distinct anus. Except in the Hirndinea, the alimentary 
canal is suspended in a capacious perivisceral space, divided 
into compartments by more or less complete partitions. The 
alimentary canal is, with one exception, not convoluted, and 
extends straight from the mouth to the anus ; but lateral diver- 
ticula are often present. 

As regards the vascular system, " no Annelide ever possesses 
a heart comparable to the heart of a Crustacean or Insect ; 
but a system of vessels, with more or less extensively contrac- 
tile walls, containing a clear fluid, usually red or green in 
colour, and in some cases only corpusculated, is very generally 
developed, and sends prolongations into the respiratory organs, 
when such exist" — (Huxley.) Tiiis system has been tenned 
the " pseudo-hffimal system," and its vessels are considered by 
Professor Huxley as being "extreme modifications of organs 
homologous with the water-vessels of the Scolecida "; since the 
perivisceral cavity, with its contained corpusculated fluid (chy- 
laqueous fluid), is believed by M. de Quatrefages to be the 
true homologue of the vascular system of Crustacea and in- 
sects. The pseudo-hKmal system, therefore, of the Annelides 
is to be regarded as essentially respiratory in function. The 
pseudo-h£emal vessels are sometimes wanting, and in these 
cases respiration appears to be effected by the cilia lining the 
perivisceral cavity. 

Respiration is effected by the general surface of the body, 
by saccular involutions of the integument, or by distinct ex- 
ternal gills, or branchite. 

The nervous system consists of a double, ventral, gangliated 
cord, which is traversed anteriorly by the cesophagus ; the 
"prx-cesophageal," or "cerebral," ganglia being connected by 




ANNULOSA: ANNELIDA. 



189 



€ 



ilcords or cominUuiresiritU Ihe"posi-ocsophagcal"j!anjjit. 
i^en(-h|)0(s, or " ocelli," are |>Tesent in niaiiy, generall)- upon 
le proboicb, sometimes in eudi segment, or on the bnocnue^ 
on the tail ; and the liead often supports two or more 
feckn which <lifler from the "antcnnx" of Insects and Cru»- 
ticot in not being jointed. 

The sexes in the Anntiida arc sometimes distinct, snd some- 

ics united in the same individual. The cnibp^os are almost 

ivcrully cilialiNl, and even in the adult cilia are almost 

•rays, if not alwa)ii, present, in both of which respects this 

cbas differs from the Arihrefoda. 

The Annelida may be <livided into two sections, chaTa<:teri5ed 
by the presence or absence of external respiratory organs or 
bntnchiic The Abranchiate section comprises the Leeches 
and the f^anh-womu ; whilst the Branchiate division includes 
the Tiibc-worma (Tiibiioh) and the Sand-worms {Errattiia), 
'Ihe Anittiida arc also often divided into two sections, called 
CAat^hon and Diswpkora, according as locomotion is effected 
by chithioas setK (Eanh-worms, Tube-worms, and Sond-wonns) 
or bjr suctorial discs (leeches). 




CHAPTER XXIX. 

ORDERS OF ANNELIDA. 

:r I. HlRUniKEA {Discophora or Siutcria). — This order 
includes the Leeches, and is characterised by Ihc posses*iioii 
a locomotive and adhesive sucker, jiosteriorly or at h»tli 
tremilies, and by llic absence of bristlet and fool -tub en:! ci. 
The sexes are united in the same individual, and the young do 
pass through any metamoqiho^is. 
liie Leeches arc aquatic, vermiform animals, mostly in- 
biting fresh water, though a few species arc marine. Loco- 
lotion it effected either by swimming by means of a serpentine 
of the body, or by mc:Lns of one or two Mictorial discs. 
forms in which there is only a single sucker (posterior), 
d or anterior extremity of the body can be converted 
into a suctorial disc The body is ringed, as many as one 
hundred annuUtions beinf^ present in the common I^eth ; hut 
it is not divided into distmct somites, and, with one exception, 
there ve no lateral appendages of any kind. The mouth is 
KneUmcs edentulous, but it is usually armed with Iccth. The 




190 



MANUAL OP ZOOLOGY. 



alimentary canni is short, nrxl U iinii»j to the skin 1>y mCttUt 
of a spongy vascuUr tissue. 'I'hc psciidoh.Tmal s)'sicin con- 
sists principally of four great longittidiDal minks, connected by 
latenJ veuels, and devoid of any special dilaladofu.* Rcspir- 
atioD appears to be porlly effected by means of a number d 
sacs, which are formed linipty by an involution of the integu- 
ment, and n-hirh oi>en externally by minute a]>eTture!>, termed 
"stipnata," In the common l.ccch there arc about seventeen 
of these vesicles on each side v( the body, their o]>cnings being 
placed on the abdominal surface, llicsc saccular in^-olutions 
of the integument ccrL-iinly secrete the mucus with which the 
body of the animal is lubricated ; and it is believed by some 
that tlicir function is solely excretory, and that ihcy answer to 
the kidneys of higher animals. In tliis cue respiration roust 
be effected by the general surface of the body ; but there is 
no rmson why the same organs should not pcrionn both fiinc- 
tions, since a close relationship subsists between the tiro. 
These sacculi ate generally known as 
the " segmental oigajis," and in most 
of the Hirudinta they arc closed inter 
nall^, and only open externally by the 
" stigmata." In some of the Hirudima, 
however, the " segmental oi;gans " a^ee 
with those of the great majority of the 
Annclidcs in not only opening exter- 
nally, but in also comnnini eating inter- 
oally with the perivisceral cavity. The 
segmental organs of the Leeches differ 
further from those of the other Anmltds 
in not being in any vay cormeclcil with 
the proce«s of reproduction. 

The nervous system consists of a 

pnc-cesDphagcal ganglion, which gives 

branches to a number of simple eyes, 

or ocelli, which are placed on the bead, 

Tie ».— Kirudinei. a Tti* and wliich ts United by lateral oesopha- 

Ji'5^^':r!:.'ilx;"; ^t^. ^^''"i* «<> ""^ ^<^'«^»» 8^.gi.ated 

SS'.TIS'lSAu'il^l '111* ««t« "c united in the »« 
f OMorth«j»wij««h^ individual, but the Leeches arc neves- 
uo tiu/nuritln "^ "" " thclcss iRcapablc of scif ■ fcTtilisatiaL 




i 



' If Bramkifhddla he r«(pitd<d u a Inie LcmH, ihen lh« abnniM rf 
f^Wt ii not univtru-l in thia onlcr, for it pouetMs branchlir. It Iib> Ihw 
■udwn, and U {Huuitic on the T arpcto «M ob Om <if^ of ihg Crayfiaik 





ANNULOSA: ANNELIDA. 



191 



sacKcr 
Mbuich 






qnoditclion, also, is aln-.iys cfTcctcd by means of the smes, 
and never by lission or gcmmntion, 

The common Horsc-ltech is only provided with a few blunt 
icctb ; but the >ltdicinal Leech {Sanguituga eJ^inalU, fig. 57) 
has. its mouth furnished with thice CT»ccntic jaws <he convex 
furiaoea of whicli are urrated with minute teeth. Tliis species 
b diiefly imported from l^imgarv, Ilohcmia, .-^nd Kti.vdA. In 
Sanpiisiiga medkinaJis, also used in rocdicinc, the abdomen 
has numerous black spots. In both species the ontl and 
catidal extremities are narrowed before dilating into the 
■ackers, and the body has from ninety to one hundred rings. 
~'he marine P^nlobdtlla have the body tubercubted, and 
themselves to the bodies of lishes, especially skates, 
aoterior tucker is separated in these fn^in the body by 
a distinct consuiction or neck. In the tittle fresh-water 
Citptina the .interior sucker is wanting, and there is a pro- 
boacidiromi mouth. 'ITicy arc found attached to the stems of 
water-plants. 

OnoER II. Oi.iGoca«TA {Terriicla). — The members of this 
order, coniprisinf; the E^rth-worms {tumfrmidtt) znd the 
WateTfrocms {J^tiliiia), are distinguished by the f^cl th»t tlldr 
looniMitif'V au))endagcs arc in the form of chitinous seta: or 
bfistlcs, attached in rows to the sides and ventral surface of 
tlie body. They arc all hermaphrodite. I1ic O/igc^Aa/u arc 
divided into the two groups of the Ttrrieif/^ or Earthworms, 
and the LimUcitt or Mud-worms and Water-worms (SaHurida 

id NaiiliJa). 

In the common Earth-worm (f.um&ruus) the body is cylin> 
'drirjil, attenuated at l>olh extremities, and carrying in ilie adult 
a thickened xonc, which occupies from six to nine rings in 
the sntenor part of the body, is connected with rei>ro<luc- 
tion, and is termed the "clitcllum," or "saddle." Locomo- 
tion is eflecled by eight rows of short bristles or setae, four of 
which arc placed laterally and four on the ventral surface of 
the body ; these representing the foot-tubercles of tlie higher 
Annelides. The mouth is edentulous, and opens into a snort 

sphagus, which leads to a muscular croj), or " pro-ventricu- 

** succeeded by a second muscular dilatation, or gizzard, 
intestine is continued straight to the anus, and is oon- 

ictcd in its course by numerous transverse septa, springing 
from the walls of the perivisceral cavity. Tlic penmccxd 
cavity (as in alt the Olij^haia) is lined by a cellular mcm- 
bfiae, which is continuous with a yellow cellular layer covering 
the intestine and buse vessel, and whic h cuts off its ct;lU into 
thcperivisceral fluid T/ic jjscudo-h^mal system isweA ^- 



m. 




192 MANUAL OF ZOOLOGY. 

veloped ; and there exists, in even greato- nnmben, Ae i 
series of lateral sacculi or " s^mental organs " which we hare 
seen in the Leeches, and which have either a respinitoiy or a 
renal function. In all the Oligochaia the segmental organs 
communicate internally with the perivisceral cavity as wdl at 
externally with the outer medium. A portion of the segmcatil 
organs is ciliated, and in all cases the segmental oigans of 
certain of the s^ments have the special fiinction of acting ai 
efferent ducts for the generative organs. 

Of the little Ndididit, the most familiar is the Diiifex rttm- 
lorum, which is of common occurrence in the mud of pondi 
and streams. It is from half an inch to one inch and a half io 
length, and of a bright-red colour. The pseudo-hffimal system 
is provided with two contractile cavities or hearts ; and theie 
is present the same system of lateral tubes, opening cxteniaHj 
by pores, as occurs in the Earth-worms. 

The Naidida are chiefly noticeable on account of the sin- 
gular process of non-sexual reproduction which they present 
before they attain sexual maturity. In this process the Sm 
throws out a bud between two rings, at a point generally neai 
the middle of the body. Not only is this bud developed into 
a fresh individual, but the two portions of the parent marked 
out by the budding point likewise became developed into 
separate individuals. The portion of the parent in front of the 
bud develops a tail, whilst the portion behind the bud develc^ 
a head. Prior to the detachment of the bud, other secondary 
buds are formed from the same segment, each in front of the 
one already produced ; and in this way, before separation takes 
place, a chain of organically connected individuals is produced, 
all of which are nourished by the anterior portion of the primi- 
tive worm. Besides their non-sexual reproduction, the NdidUk 
possess generative organs when adult, and exhibit true sexual 
reproduction. With the development of the generative organs, 
a new segment is added to the body, and certain other modifi- 
carions take place ; so that the process of attaining sexual ma- 
turity is actually attended with a species of metamorphosis. 

Order III. Tubicola (C^:4fl/(i*rfl«cAM(ii).^The Annclides 
which are included in this order inhabit tubes, which may be 
calcareous, and secreted by the animal itself or may be com- 
posed of grains of sand or pieces of broken shell, cemented 
together by a glutinous secretion from the body. The body- 
rings are mostly provided with fasciculi of bristles set upon 
lateral foot-tubercles or parapodia, by means of which the 
animal is enabled to draw itself in and out of its tube. .The 
aJimentary canal is loosely attached to the integument The 



ANKULOSA : ANNELIDA. 



193 




TWcois src onieexual, and Ibc young pass through a neta* 
laorphoois. 

When tlie tube of a Tubicolar Annelide is a true calcareous 
Kciciion rrom the body of the anini.-il, it U, neverthctcn, 
readily distingiiiihed ttom the shell of thcMwlliisc.i.by ihc fact 
that ^eic is no oiganic connection of any kind bciwccn the 
animal and its tube. 

The pseudo4ia:mal system has its usual arrangement, and 
the contained fluid is usually red in colour, but is olive-green 
in Sabei/a. The rcspiTatof>' or- 
gans are in the focm of lilament- 
ous braochix, attached to, or 
near, the head, generally in tm> 
lateral tofts, unnged ina funnel- 
thapcd or spiral wna. Each fila> 
tncni is frtngcd vrith vibrating 
cilia, and the tufU are richly sup- 
ulied with fluid frotn the pscudo- 
uemal system. There b no spc- 
nal ap|jur:iius retiuired to drive 
Ihc blood back to the heart, 
tmt thb is effected by the con- 
tractile power of the gills thctn- 
tehres. From the position of 
the bnnchise upon, or near, the 
bead, the Tuscola arc often 
Icoovm as the " cephalobranchiatc " Annelides (fig. 5S). 

Rcprodiu-tton in the Tti&iccia is generally se)cual, the sexes 
Ming in difTcTctit individuals ; but s|>ontaneous Bsiion has also 
)eca observed. As regards their dcveloiiment, the process has 
t)ccn thus described, as it otnim in Tertirella.- — 'ITic embryo, 
irhkJi b at first a free-swim ming, cilt.iie<l body, " lengthens, 
ind the cilia, which were at first generally diffused, become 
confined to a dncturc behind the head, a transverse ventral 
band near the tail, and a small circle round that part. I'he 
daad b dbtinguished by two red eyc-spcck* ; new segments 
tre SDCccssively added, one behind the otlter, and always in 
Voot oS the anal one ; but aa yel Uie embryo is apodal. The 
ubcTclcs and seta; are next developed in the same order, and 
1 free-swimming or "errant" Annelidc ensues. V'in.illy, the 
-ilia oi the buccal ring* are lost, the young Trrfbdla reposes, 
md envelops iisdf in a mucous tube" — (Owen,) As the 
roung tubicolar Annelide is thus frw. or " errant," before it 
>ccoines (iiully enveloped in a tube, it is gcncratly believed 
hat the Tuiwia should be looked uj>on as really \ii^V\ci vWtv 

N 



ric. tl.-T\iUa>1t. 



«rrAiMinn^ ttuwlni ih* hMihU 
and apwculiun i iSj 







194 MANUAL OF ZOOLOGY. 

the next order of Anndida — viz. the Errantia. It sppeni 
however, more probable that the stationary condition of the 
adult Tubicola should rather be regarded as an instance of 
" retrograde development." 

The most familiar of the Tubicola is the Serpula (fig. 58, a), 
the contorted and winding calcareous tubes of which must be 
known to almost every one as occurring on shells or stones on 
the sea-shore. One of the cephalic cirrhi in Serpula is much 
developed, and carries at its extremity a couical plug, or oper- 
culum, whereby the mouth of the tube is closed, when the 
animal is retracted within it. The operculum of Serpula has 1 
more than ordinary interest in the fact that it is the only in- 
stance in the Annelida in which calcareous matter is deposited 
within the integument In Spirorbis (fig. 58, b) the shelly tube 
is coiled into a flat spiral, one side of which is fixed to some 
solid object. It is of extremely common occurrence on the 
fronds of sea-weed and on other submarine objects. 

Equally familiar with Serpula is Terebella, the animal of 
which is included in a tube composed of sand and fragments 
of shell, cemented together by a glutinous secretion. In the 
Sabellida the tube is composed of granules of sand or mud. In 
Pectinaria the tube is free, membranous, or papyraceous, and 
in the form of a reversed cone of considerable length. 

Order IV. Errantia (Nereidea). — This order comprises 
free Annelides,* which possess setigerous foot-tubercles. The 
respiratory organs are generally in theform of tufts of exter- 
nal bmnchize, arranged along the back or the sides of the 
body. They are unisexual, and the young pass through a 
metamorphosis. This order includes most of the animili 
which are commonly known as Sand-worms and Sea-wonn^ 
tf^ether with the familiar Sea-mice. 

The integument is soft, and the body is very distinctly 
divided into a great number of rings or segments, each w 
which, in the typical forms, possesses the following stnicturt 
The segment consists of two arches, a lower or " ventral are," 
and an upper or " dorsal arc," with a " foot-tubercle " on each 
side. Each foot-tubercle consists of an upper process, or 
" notopodium," and a lower process, or " neuropodiura," eadi 
of which canies a tuft of bristles, or " seta," and a spedet rf 
tentacle termed the " cirrhus " (fig. 56). 

The anterior extremity of the body is usually so modified 
as to be distinctly recognisable as the head, and is provided 

* Fritz MiillerdeiicnbFS ancmnt Annelide belonging (o Ihe ^ mfkinftioi* 
as living patasilically within the shell of the common Bamacle {L^aii, 
ihowing that theineinbeno{i.bUt^u,Vi>^]r so°>etimesloMtiicii&M^tib. 




ANNULOSA: ANNELIDA. 

■nd with Wo or mote feeler*, which are not jointed, 
C therdbrc, not compAr^ble with the jitiIciiiuc of Cms- 
md inaeos. The mouth is placed on the inferior sur- 
dw bead, and is often furnished with one or more pairs 
ly Jaws, working laterxJly. The phiU}-nx is muscular, 
rms a son of probosciK, being (tfo\-ided with «i>ecial 
t, br oKons of whicli it can be everted and again re- 
. In most there is no diKiinction between stomach and 
IK, and the epithelium of the alimentary canal, like that 
preceding orders, is ciliated. The perivisceral cavity 
with a colourle^ corpiisculatcd fluid — the " chylaquc- 
" — which " i>crforras one of the functions of an intcr- 
teton, aciinj; as the fulcrum or base of rcsi&Uince to the 
muscles, the |)0wer of voluntary motion being lost 
fluid is let oul" — (Owen.) 
meudo-hunol system is iretl developed, and consists 
lily of a long dortal vessel, and a similar ventral one, 
ted by transvene branches, and furnished at the bases 
branchiic with pulsating dilatations. The contained 
mostly red, btii is yellow in Aphroditt and F^j/nne. 
liration is carried on by means of a series of external 
ia: or gills, amuwed in lufu upon the vides of the body 
dOTMl aspect, alons the middle of the body only, or 
Its entire length, trom the position of the branchiae 
bcrs of this order arc often spoken of as the " Dotsi- 
te" (of more propedy " Notobnnchiatc ") Annclides. 
scgmenial organs." with few exceptions, communicate 
[terivisceral civiiy internally, and in certain segments 
always specialised to act as efferent ducts for the re- 
ive organs. 

Scamousc {Af-hrodilt, fig. 60, B), the back is covered 
double TOW of membranous imbricated plates, which 
elytra." or " jquanva;," and respiration is effected 
periodical elevation and depression of these plates, 
water is altem.-itety admitted into, and expelled from, 
beneath them. This ^pace is separated by a membrane 
le pciivisceral cavity below, and contains the gills in the 
smalt flctJiy crests. The pharynx is thick and muscular, 
be everted like a proboscis, and the intestine has a 
of lateral branched cxcx 

nervoas system in the Errantia has its typical fonn, 
of a double ^nglialed ventral cord, two ganglia of 
are appropriated to each segment 1'he pnc-ivsopha- 
cerebral, ganglia are of large siie, and send filaments 
ocelli and feelers. 



196 



MANUAL OF ZOOLOGY. 



Th« sexes in the Erratilia are in diflerent individual!, i 
reprtiduction » usually MNiual, though in some cases fgaaaa^ 
tion is known to occur. The process of gemmation is cund 
on by a single segment, and so long as it continues, the bod- 
ding indivtdual remains sexually immature, though the foung 
thns produced develop generative organs. 'I'hus, there is in 
these cases a kind of alternation of generations, or rather to 
alternation of generation and gemmation ; the oviparous indi- 
viduals producing eggs from wliich the geiiuniparous inditi 
duals are bom ; these, in their turn, but by a non-sexual [«» 
cess, producing tlie oviparous individuals. 

liie embryo usually appears on its liberation from the ovun^ 
Rs a free-swimming ciliated body, posi«Ksing s mouth, intcstise 
and anus. The cilia arc primarily diffused, but become aggrc- 
gaicd so as to form a smgle median belt, of two bands, one 
about each extremity. The head, with its fedets and tyt 




IV Jf-'" Bmm " Annctidc. .Vr-r,*i, Oinrisc ihc " bud ' irith iu »ppndi((k 

specks, appears at one extremity, wrhiUt the segments of Oie 
body begin to be formed al the other. Each segment is dcv-d 
oped ill four ]»ans. the two pnncijMi! ones forming lulf-rinp\ 
united by shorter side-pieces, from which the seligcrous fool 
tubercles arc developed. The cilt.ited band or baivds finiUj 
disappears, an<i new rings are rapidly added by inteicaliiioo 
between the head an<l the segments already formed. 

Amongiil the best known of the Ermmia i.t the comrnc 
Lob-womi {j^rrniofia pisatomm. fig, 60, C), which is uwd bfl 
fishermen iut bjiit. The Lob-womi liven in deep canals wbitftl 
it hollows out in the sand of the sea-shore, literally eating \ 
«ray as it proceeds, and passing llie siind through the aline 
aiy canal, so as to extract from it any nulrimcnt which it nu< 
contain. It possesses a large heiul, without eyes or jaws, ana 
with a short proboscis. There ate thirteen pairs of bivubi*. 
jilaccd on each side in the middle of the body. 

In the Alcroi/d, ot " Sc&<«nti^^edes," the body is grtiatlr 




ANNULOSA: ANNELIDA. 



'97 



donated:, and consitts of a great number of similar s<^ents, 
with rudtmcntaTjr brancluK. The head is (lixlinct, and carries 
eyes and feekn, whilst the mouth is rumixhcd with a large 
proboscin, and often with liro homy jaws (iSg. 59). In the 
Etmkta the branchiic arc usually well dc^'cloped and of large 
site, ftud the mouth is armed with seven, eight, 01 nine homy 
jaws. EunUe gi/^HtM attains sometimes a length of over four 
feet, and nuy consiat of more than four hundred rin^. 

DtsnciBtmoN of Akxklida in Time. — Ofthe'^wwi'/'ii'fi the 
only orders which are known to haw left any traces of their 
existence in (latt time are the Tubitola and the Errantia; of 
which the former are known by their in^vsting tubes, whilst 





C Lvlr-wHia (>4 mt(M>V (Ana Com*,) 

the latter are only recognised by the tracks which they left 
upiin anLieni sca-bolloms, or by their burrows in sand or mud. 
Tliese tracks and burrows of Annelidcs arc found commonly in 
rocks of almost all ages from the Cambrian period upwards. 
Thnw tracks which have been caused simjily by llie passage 
of the worm over tJie surface of the mud are termed by Mr 
Salter Hdmmikita, whiLit the burrows arc called SaliUt (or 

Tubicolar Annelido; are known to occur from the Silurian 
Rocks u[>ward<. The well-known Silurian fo&Ml, TentamMrt, 
is generally believed (o belong to IhU order, but it is referred 
by M. Banandc to the JVm^^oAi (MfiSusta), Cornulitti ut& 



198 MANUAL OF ZOOLOGY. 

TVachyderma, however, are undoubted Silurian 7)tiia>UL TTm 
Microcomhus carbonarius is a little spiral Tubicolar Aimclidtv 
nearly allied to the Spirorbis (fig. 58, S) of our seas, irtiich it 
not uncommonly found in strata belonging to the Carbom- 
ferous period; and the genus Spirorbii itself is rc^esenttd 
even in the Silurian period. 

TABUIAR VIEW OF THE AHNELtDA. 

Division A. Abranchiata. — No external organs of respintion. 
Order I. Hirttdinta. — No bristles or foot-tubercles ; locomotion ^ 

Di«im of 1 suctorial disc at ooe or both extremities. lU. C«i. 

Himdo, CUpsine, PontobdtUa. 
Order II. 0/igccAifta. — Locomotion by means of rows of stiff brittld, 

or"seti;"nofoot-tubercle». lU. Gen. ZnM4nViu,Ai*, TWjIii. 

Drvisiim B. Brancriata. — Respiratory oi^ns in the fonn of atentl 
branchiae. 

Order in. Tubicola. — Body piotecled by a calcareaoi or aTenacow 
tnbe. Branchix attached Co, or near, the head \jC^kai^iTtaKkia^ 
Itl. Gen. Serfula, Terebella, SaUUa. 

Order IV. Erranlia. — Animal free, wilh Eetigeious foot-tuberdo. 
Branchise in tuFls, attu:hed on the sides of the body, in the middlt 
of dorsal region only, or along its entire length {DBriiimiiJiialsl 
III. Gen. Arenicola (Lob-wonn), Nirds (ScB-CcQlipedc), AfAreiiU 
(Sea- mouse). 

Class III. ChiEtognatha (Huxley). — The remaining cUa 
of the Anarthropoda has been recently constituted by Professor 
Huxley under the name of Cfiixfognatha, for the reception of 
the single genus SagUta, which had been formerly placed 
amongst the Annelida. By Professor RoUeston, however, the 
Chatognaika are placed in the division Nanatdmia of the 
Annuloida, in the immediate neighbourhood of the Nms- 
toidea. 

The Sagilla are singular marine animals, transparent, and 
elongated in form, and usually not mote than an inch in 
length. The following are the characters ascribed to the das 
by Huxley : — 

"The head is provided with several, usually six, sets of 
strong, bilaterally symmetrical oral setae, two of which, long 
and claw-like, lie at the sides of the mouth ; while the other 
four sets are short, and lie on that part of the snout which is 
produced in front of the oral aperture. The posterior part of 
the body is fringed on each side by a delicate striated fin-like 
membrane, which seems to be an expansion of the cuticle. la 
some species the body is beset with fine setx. The intestine is 
a simple, straight tube, extending from the mouth to the anus; 
Ae latter opens on iKe \en.aail sur^e, just in front of the 



ANNULOSA : CHiETOGNATHA. 



199 



hinder extrcmily. A single oval ganglioD lies in the abdomen, 
and sends, Ibrwards and backward^ two pairs of lateral cords. 
The lateral conLi unite in front of and above the mouth into a 
hcjufionjtl ganglion. This fpves off two brandies which dilate 
at their extrcinitics into the «i>heToidal ganglia, on which the 
darkly pigmented iinpcrfccl ^-ca rc^t. The ovaries, saccular 
organs, tic on each side of the intestine and open on cither side 
of the vent ; receplaeula leminit arc picscni. Behind the anus, 
the cavity of the tapering uiidal part of the body is partitioned 
into two compATtmunis; on ilie lateral pari cies of lhe.se, cellular 
masses are develo)>eil which become detached, and, floating 
freely in the comiiamneni, develop into spermatozoa. These 
escape by spout-like lateral ilu<-t», the dilated basex of which 
perfofm the port of wsuuia ifminai/s. The cmhryos arc not 
ciliated, and undergo no metamorphosis."— {See Inlroduaim t« 
tie Ciaisifiataa qJ AHtmaU, p. 5a.) 




CH.\PTER XXX. 
ARTHROPODA. 



DiirtstOM II ARTHitoPot>A. Oft Akticvijita. — The remaining 
mctabers of thq sub-kingdom Annuhsa are diuingiiished by 
the possession aiJotDtfil iifi/vniiaga. ariicuiated to Ikf ^y; and 
ihey form the second primary di virion —often called by the 
ttame Artiaihia. As this name, however, has been employed 
in a wider sense than is understood by it here, it tx, perhaps, 
best to adopt the more modem term Arlhr^da. 

The members of this division, compriking the Crustatta 
(Lobsters, Dubs, &c|, the Aratknida (Spidcra and Scorpion.s), 
ibc Mj^iapnta (Centi|)edes}, and the Insula, are distinguished 
as follows: — 

The body (fig. 54} is composed of a scries of segments, 
unnged along a longitudinal axis ; each segment, or " somite," 
oecuiOBally, and some always, being provided with articubtcd 
appendages. Both the segmented body and the articulated 
Ifanba are more or less completely protected by a chitinous 
exoskelcton, formed by a hardening; of the cuticle. The 
appendages arc 1k>IIow, and the tnii.iclo are prolonged into 
ibetr mterioT. llie ncrvoo.s system in all, at any rate in the 
mbryonic condition, con%i»ts of a double chain of ganglia, 
placed along the ventral sadace of the body, united b^ Wgr 



200 MANUAL OF ZOOLOGY. 

tudinal commissures, and traversed anteriorly by the oesoplugiis. 
The hsemal system, when differentiated, is placed dorsallj, and 
consists of a contractile cavity, or heart, provided with valvular 
apertures, and communicating with a perivisceral cavity, con- 
taining corpusculated blood Respiration is effected by ^ 
general surface of the body, by gills, by pulmonary sacs, or bj 
tubular involutions of the integument, termed "trache«." In 
no member of the division are vibratile cilia known to be 
developed. According to Professor Huxley, an additional 
constant character of the Arthropoda is to be found in tbe 
structure of the head, which is typically composed of six s^ 
ments, and never contains less than four. 

The Arthropoda are divided into four great classes — vit, tbe 
Crustacea, the Arachnida, the Myrkfwda, and the Ituecta; 
which are roughly distinguished as follows : — 

1. Crustacea, ^^ir/iro/ww by means of gills, or by the gaunl 
surface of the body. Tmo pairs of antenna. Locomotive appa- 
dages more than eight in number, borne by the segments of He 
thorax, and usually of tlie abdomen also. 

2. Arachnida. — Hespiration by pulmonary vesicles, by trachea, 
or by the general surface of the body. Head and thorax uniiti 
into a cephalotkorax. Antenna (as such) absent. Legs ei^. 
Abdomen without articulated appendages. 

3. MvRiAPODA. — Respiration by trachea; head distinct; re- 
mainder of the body composed of nearly similar somites. One 

pair ofantennte. Legs numerous. 

4. Insecta. — Respiration by trachea. Head, thoreue, and 
abdomen distinct. One pair of antenna. Three fairs of lep, 
borne on the thorax. Abdomen destitute of limbs. Generally tm 
pairs of wings on the tliorax. 



CHAPTER XXXI. 
CRUSTACEA. 



Class I. Crustacea. — The members of this class are com- 
monly known as Crabs, Ix)bsters, Shrimps, King<rabs, Bar- 
nacles, Acom-shells, &:c. They are nearly allied to the suc- 
ceeding order of the Arachnida {Spiders and Scorpions) ; but 
may usually be distinguished by the possession of articulated 
appendages upon the abdominal segments, by the possession 
of two pairs of antennae, and b^ ihe presence of branchia:. 



^wr^ 



ansulosa: crostacka. 



201 



I "Id the Crvttaiea the body is dislinguishahle into a variable 

I number of 'aomiten,' or definite ne^inents, c^di of vrhidi raay 
be, and jotne of which always arc, [irovided with a single pair 
of utkolatcd a]>pcnd.iges. ... In most Crti»iacca, and 
probabty in all, one or more pairs of appcndAgc-n are so modi- 
fied as to subserve manducation. A pair of ganglia is primi- 
tively developed in each somicc, and the gullet posses between 
two successive pours of ganglU, as i» ihc Annelida. 

" No trace of a water- vascular systeni, nor of any vascular 
lysteni similar to that of the Annelida, is to be found in any 
Cmitaceaa All Crustaeea whitih possess deAnite respiratory 
organs have btanchisc or ouiwiu'd i>tdc«Scs of the wall of the 
body, adapted for respiring air by means of water; the terres- 
trial lupidtti sonK of which exhibit a curious rudimcninry 
representation of a tracheal system, forming no re-^l exception 
to this rule. When they arc provided with a circiilaiory organ, 
it is situated on the opposite side of the alimentary canal to 
the prindpat chain of ganglia of the nervous system ; and com- 
munidtes by valvular apertures with the surrounding venous 
sintu — the »o-callcd ' pciicardium."* — (Huxley.) 

In addition to these characters, the body in the Crutlaeea 
is always protected by a chitinous or sub-calcareous exo»kc- 
letoD, or "erase," and the number of pnirs of articulated limbs 
is generally from five to seven. They all jiass through a scries 
of metamorphoses before attaining tlicir adult condition, and 
every part that is found in an einbr}'onic form, even diough 
only temporarily devclo|>cd. maybe represented in a permanent 
condilion in some member of a lower order. 

The classiAcation of the Crustacea is exlrcmely complicated, 
ind hardly any two wTiteis adhere to the same airangcmcnt. 
The tabular view whidi follows embodies the arrangement 
which appears to be most generally adopted, and the diagnostic 
chancters of each order will be briefly given, a more detailed 
desciiptioa being reserved far the more important dtvi.sionx of 
the class. Before proceeding further, however, it will be as well 
(Ogive a description of the morphology of a typical C'riMlaefaii, 
•dectioK the Lobster as being as good an example as any. 

The body of a typical Crushuean may be divided into three 
regions — a htad, a fAt>rax, and an a^dimen, each of «hich is 
cotnposcd of a certain number of somites, though opinions dilTcr 
both as to the number of seginents in eadi region, and as 
to (heir number collectively. By the majority of writers the 
body is looked upon as being tyi>ica1ly composed of tumty-me 
•cgmenu, of which seven belong to the head, seven to thv 
thorax, and seven lo the abdomen. In many Crif{Jiu«i,Vo«- 



202 



MANUAL OF ZOOLOGV. 



ever, the s^ments of ihc head nml thonu are w«tded to^tntr 
into a single mas&, callt-d the " cephalolhortx ;" in which cue 
the body shows only two distinct divisions, of whtcii the cephalo- 
thorax claims fourteen segments, whilst the remaining scvoi 
are allotted to the abdomen. By Professor Huxtcy. on the 
other haiid, the terminal joint of the abdomen, tcnned the 
" teLton," is regarded ox an af^aJagf, and not at a Siontitc. 
Upon thLt view, the body of a typical Crustacean will consist 
of to'enty segmcnU only. Professor Husky, further, diffen 
from the above-mentioned view in the allotmenl of the somites, 
and he divides the body into six cephalic, eight thoracic, aad 
six abdominal somites.* Fri« Miillcr and Claus deny that the 
eyes are limbs, or that there is an ocular segment. The tclsoo, 
on the other liand, is regarded by the former as a true somitt; 
chieDy because the inicHtine umally opens in this piece. 

Whilst tile nonnat number of seRDients in tlie body oJ* any 
Cnistaccan may thus be regarded u beins twenty-one, a 
twenty, there occur esses in which this niun&er is exceeded, 
and others in which the number of somites U appiirenlly leu 
In these latter cases, however, the apparent diminution in the 
number of segments is really due to some having been fusoi 
toj^etber, as is shown by the number of appendages, since each 

fiair of api>endagcf indicates a sqnuate somite. In other cases, 
lowever. m which the number of somites is really less than the 
normal, this is due to an urett of developmenL According to 
Mitnc- Edwards : — 

" In [he embryo these segments are formed in sitccecMa 
from before backwards, so that, when their evolution iscbeckod, 
the Uter, railier than the earlier, rings arc those which ate 
wanting ; and, in fact, it is generally easy to see in those spea- 
men.s of full-grown Crustnceous snimals whose bodies present 
fewer than twuntyonc segtnciits, thiit the anomaly depends DO 
the absence of a certain number of the most posterior rings of 
the body." According to Dana, however, the abortion of 
segments, with tlieir appendages, almost always takes place at 
(he posterior end of the ccphalothumx. 

In no single example can a general view be obtained of the 
different segments and their appendages in the Crtiffaav, 
" Indeed, the only segment that may be said to be persistcnl, 
is that which supports the nundibtes, for the eyes may be 

* In naMty the (itc hindmott xegmcnl* of the djhl Minitei here attolNd 
t<> llie thocu. should sUrfic t>f rt^rdid u oiutliuiiiiE the atdtmfn proper, 
~lhal is. Ihc region cortnpondini; ID tha " aliilomcn' of intccitand An<h* 
nidi. The MI lomile* nllottAl above lo th« tUtmtn bdoa( towtath 
uriclly cnUcd the "fM-aMnmeH " of Ibe Cnalatm, 




ANNULOSA: CRUSTACEA. 



203 



tiling, and the ant«ntuc, thmigh lesn liable to duingn than 
'the remainir^ apj^ndagcs, arc nevertheless aubject to very 
extnordinaiy iDoaificationK, and have to jicrfonn functions 
equally various. Udng essentially and tyiiicilly oigans of 
touch, hearing, at>d {m-tIuiih of uncU, in the highest Decapods, 
Ihcy become converted into burrowing organs in the S^yilaru/a, 
organs of prehension in the M(n>slDma/a, claspcre for the male 
in the CydopoiAa, and organs of attachment in the Cirrt^ia, 
Not to multiply instances, we have jwcHcnted to tis in the 
Cruilacta pralMOly the best xoologiral illiiMiation of a class, 
conbtrurted an a common type, retaining ilK general dumcier> 
istics, but cafxililc of endk-^s modifiraiion of its {Mrtti, so as 
10 mit the extn-mc requirements of every separate species." — 
(H. \V<».)w3rd.) 

Taking the common Ixibsier (Sc. 74) as a good and readily 
obtainable type of the CmttMea, the Iwdy i» at once seen to 
be compooed of two ports, familiarly called the " head" and 
the " tail,"* the latter W%nf, jointed nnd lltxiMc TTie so-<:alled 
"head' b really cnnipoMrd of both the head, projKirly lO 
called, and the thorax, which have coalesced so as to form 
« single mass, technically called the "cqthalo thorax," The 
eo-caUcd "tail," on the other hand, is truly the "abdomen." 
The rarious appendages of the animal are arranged along die 
~ i«rer sur&ce of the lx>dy, and consist of the feelers, jaws, 
daws, Ic^, fic The entire body, with the articulated ap- 
jieniLigOk, is enclosed in a strong chitinous "iJiell," or e<0- 
•kcleton, and the <-ephatothorax is covercti by a great ce]>lulic 
sbieM or )^c, which is termed the "carapace. " 

Kach segment of ihc body may 
be regarded as essenlislly composed 
of a i-onvcx upper plate, termed the 
•■ tdgum," which is close*! l»elow by 

flatter plate, called the " Mcmum." 
lirte where the two unite being 
lueed downwards and outwards. 

:a a plate, which is called ihc 
pleuron." or " pleura" (6g. 6j, 1). 

Stiiclly •paaktaci ()» compMiiioo oi tbe 
laooiMc iicunwderalilynKrrecoinplci, 
"flht firimsrjamof iheicnnilcbcinif 
infKM«d ot ftmi (HcocL Th« ler- 
_ tcoanptned of two nmlial piecn, 

Mw M cacb lide of the midille lln« ih tbc bdy, uniicd logrthvr, and ton- 
-■ ■- -. ,1^ "icrjuBi" prv[irr, T!i* HijMtriur «ic n c(>n>|il<tr<I hy l«i> 
oiic on nch Me of the Itrgum, nhich arc Icrmnl the 
111 liLe auin«r the ventnl or iicmal otc u ccmpoted of 



^. 




?.->» 



FlCi <■.— TheomiaJ fifunilliu- 
(rating the ctimt^taitutotl llio 
Hpimnuo' •LtlMan cT tlM 
C(u*u«B infrcr Milfie ■ E4 ■ 
■nrdi) D [lofHil mt; * I 

ptKn -. V VcnfnJ hni I t 
SMnHil iiircn ; // EpLUcmil 
pitm, // Inii'iian of lb* 
cnlfTiniticL 




304 



MANUAL OF ZOOLOCV. 



ntn] pUte. coinpoMd of Iwo picwt untied Mgclbcr inlbe tnicldleliiN^ 
I eoiutituciec ih« "ti<muiii" prap«*i (he mc tmnj; cxiinpUted bylwo 
'ixeai pin^^ Itnnoct tlic " rpiHicniB." Thew )>Utn arc luually RNn m 
ItVi ccini|itcicly .iiicliytu«nl tu^llier. and l!ic Intc tlrudore o( the HMnilc 
tn theu caici ii often ihown by whnl art called "apodonaia." TliCM 
are Mpla wlii<;li proceed inwnnli Ircan ihe internal wi&oe of ihc lomii*, 
ptnetratjing more oi leu deeply lictween the tnrioa* oq^n* cnclowd tn 
the tins, end nJwayi pToceo^i>|{ from Ihc line of junction of Uic <Uflmai 
pecc«of ihcKpncnl (fij;. 6l). 



It muitt be )>ome in mind that thou|;h the socalled " head * 
— that is to Jay, the " ccphaloihorax " — of the l^obnter is pro- 
dticed ]>y an amalgamation of tlic \'arious socnilcj of the aa>6 
ontl thorax, this is not the c^fio with the grcti shield which 
covers this ponion of the body. This shield — the so-called 
"cephalic buckler," or"carapa«r" — is not producol by the 
union of the terj^al arcs of the various cqihalic and tborade 
segments, as would at first sight apprar to be lite case. On 
the contrary, the "<:nrapace" in the higher CruiUt(fa is pro- 
duced by an enormous development of Ihe tcrg-.il pieces, or of 
tlie " epimen " of one or t«-o of the cephalk segments : the 
tergal arcs of the remaining somites being overlapped by tbc 
carapace and remaiaing undeveloped 

Examining the somites from behind forwards (for simplici- 
ty's sake), Ihe last segment comes to be first described. This 
is tlie so-called " telson," which forms the last articulation of 
the iiMomen, and never bears any aj>pe»dages. For thit 
reason, many authorities do not regard it as a somite, properly 
speaking, but simply as an a/^'gos appendage — that is to say, 
as xn appendage without a fellow. In the next segment (the 
last but one, or the last, of the abdomen, according to the view 
which is taken of Oic " telson "), there is a pair of natatory ap- 
pendages, called " swimmerets." Each swimmeret <lig. 62, 1) 
consists of a basal joint, which articulates with the stemuRi, 
and is ca]le<l the "protopodite" or pro|>odite, and of i«x> 
diverging joints, which are attached to ihc fonner; (he ootei 
of these being calleil the " exopoditc," and ihe inner the " en- 
dojHMliie." In this particular segment, the cxopodite and 
endopoditc arc greatly expanded, so as to form powerful pad- 
dles, and the cxoixKliic is divided into tno by a (Tansverse 
joint. In the succeeding somites of the abdomen — with the 
exception of Ihe first, in which there is some modiftcatioa — 
the appendages arc in the form of swimmercts, essentially the 
same as those attached to the iientiliinute segmtni, and differ- 
tog only ID the fact, that Ihe exoi>odite and endopodiie are 
much lUTTOwcr, and the former is undivided (fig. 63, a). Tbc 



I 



\ 





nt (k— Miwi^flicyar IjiWln, >. LcWur Kilh ill Iht tppmiigmt, ac«pl Ik* 

u rn An. a (.anpM*; r T<V»n. >. IV ihlnl tbdiiuiiiul toiaiu MfamMd. f 
Ti>Viwi I Hhhm;/ rWwnn ^ a ?niidUMl>le; « Eiii|»dii( i c brffipiiiliM > 
Om tf iIm I*m pM tf (3Di'j*<n ai muilUpcdM. f Epiptdiw; < Gill i iba (Ov 
WMiMbrftn. 



nnt tiwradc segment carries another pair of nmbul-itorr tunbs, 

Suite •imiUr to the lo-M, except for the fnct that the prolopo- 
itc bean a [uoceis which Krv«s to keep the gilU apui, Mid 



lu. 



3o6 Manual of zoology. 

is teimed the " epipodite." The succeeding segment suppaiti 
a pair of limbs similar to the last in all respects, except dot 
its extremities, instead of being simply pointed, are conTerted 
into nipping claws, or "cheUe." The next segment of the 
thorax carries a pair of chelate lirabs, just like the preceding 
and the next is tumished with appenckges, which arc ess<s- 
daily the same in structure, but are much latger, constituting 
the great claws. The next two st^ments of the thorax, and 
the segment in front of these (by some looked upon as belong- 
ing to the head, by others as referable to the thorax), bear 
each a pairofmodified limbs, which are termed " maxijlipedes,' 
or " foot-jaws," These are simply limbs with the Mdinaiy 
structure of protopodite, exopodite, cndopodite, and epipodit^ 
but modified to serve as instruments of mastication, the hind- 
most pair being less altered than the two anterior pairs (fig. 61, 
3). The next two somites carry appendages, which are in the 
form of jaws, and are termed respectively the first and secfmd 
pairs of " maxillae." Each consists of the parts aforementioned, 
but the epipodite of the first pair of maxillae is rudimentaij, 
whilst that of the second pair is large, and is shaped like 1 
spoon. It is temied the " scaphognathite," and its function is 
to cause a current of water to traverse the gill-chamber by con- 
stantly baling water out of it The next segment carries the 
biting jaws, or " mandibles ; " each of which consists of a la^ 
protojmdite, and a small endopodite, which is termed the 
" i>al])," whilst the exopodite is undeveloped. The apterture 
of the mouth is situated between the bases of the mandibles, 
bounded behind by a forked process, called the " labium," or 
"metastoma," and in front by a single plate, called the "li- 
brum" (upper lip). The next segment bears the long antennse, 
or feelers (tig. 74, ga), each consisting of a short prvtoptodite, 
and a long, jointed, and segmented endopodite, with a very 
rudimentar^■ exopodite. In front of the great antennae are die 
next pair of appendages, termed the " antennules," or smaller 
antenn.-e (fig. 74. ir\ each composed of a protopodite, and 1 
segmented endopodite and exoi)odite, which are nearly of equal 
si^e. Finally, attached to the first segment of the head are the 
eyes, each of which is borne upon an eye-stalk formed by the 
protopodite. The pill-chamber is formed by a great prolonga- 
tion down«-ards of the pleura of the thoracic segments, and 
the gills are attached to the bases of the legs. 

As n^ards the digestive system of the Crusiaeea, the ali- 
mentar)- canal is, with few exceptions, continued straight from 
the mouth to the aperture of the anus. There are no salivary 
glands, but a huge and well-developed liver is usually prescnL 




K hean is genenny, btti not always present In most of the 
lower forms it ii a long vAsirorra tube, very like the " dorsal 
vessd* of Insects. The exact course of the circuUlion has 
been diSerently rtaied by (tifTerent writers, but tlie following 
a|>pear to be the bets of the ca^e : In some of the lower fonns 
Ux; Co/i/i^Ai) there nic no arterial vessels, and the venous 
blood returned from the body is collected into a venous sinus 
-^he so-called " pciicatdium," which surrounds ihc heart and 
opens into it by valvubr apertures. In the higher forms, the 
bean gives off a number of arteries by whith the blood is 
driven to all parts of the body an<l to tlie gills. The arteries 
do not terminate in a system of aipilbr>- vcM>el>, but in a 
series of irregular lacuna: occupying aU the intcrstii n between 
the different organs of the body. From this Interstitial lacunar 
system arise the venous trunks, which arc generally dilated 
into more or less extensive sinuses. Whether the whole of 
the venous btood is submitted to the action of tlic gills, or 
whether the blood sent to the gills is derived mainly from the 
heui, is a matter of (jueslion; but i]\c former is the more 
pntnble view. Be this as it may, the blood is invariably 
relumed to a lar^e venous sinus which surrounds the heart, 
and open.t into it by a number of valvubr apcrHire*. It 
foltowE from this description, that tho heart of the Crtisteita 
is mainly, if not altogether, a tyilemU heart, being concerned 
chiefly, if not entirely, in driving the aerated blood to all |>ans 
of the t>ody. 

Distinct respiratory and circulatory organs may he alt<^elhcT 
■Wtting; but, as a rule, distinct braiichiic arc ])reKent. Tlie 
exaa fonn and structure of ibc gills difier in ilifft-rent cases, 
but their leading modifioitions will be alluded to in treating of 
the didcrcnt orders. 

P TABt;LAK View of trc Divisions op THS Crustacea. 

SobdaH I. EP120A {ffautuilata). 

I Order i. Mlhyvphthira. 
„ 2. RhUoctphaia. 
Sob^kSf II. CitttllPEDtA. 

SBftkniilK. 
Vcirueid*. 




t.cpattiil«. 



„ 4. Abdominatia. 



208 MANUAL OF ZOOLOGY. 

Sub-class III. Entomostraca. 

Order 6, Ostracoda. 1 r - t t ^ 

„ -i. Cop^a. }.£«»«, Lophyropod-. 

„ 8. aadocera. \ 

„ tj. Phyllopoda, > Z-yw«, Brancliiopodi. 

„ 10. Trilobita. ) 

„ II. Merostomaia. 

Sub-class IV, Malacostraca. 

Division a. Edriopkthalhata. 

Order 12. Lmmodipoda. 
„ 13. Isopoda. 
„ 14. Amphipoda. 

Division B. Podophthaluata. 

Order 15. Siomapoda. 
„ 16. Decapeda. 

Tribe a. Macrwa. 
„ b, Anomura. 
„ c. Brcuhyura. 



CHAPTER XXXII. 

EPIZOA AND CIRRIPEDIA. 

Sub-class I. Epizoa {Haustdlata). — The members of this sab- 
class of the Crustacea are in the adult state parasitic upon the 
bodies of fishes, and are usually deformed ; but in the young 
condition they are locomotive, and are furnished with anteonx 
and eyes. The mouth is suctorial, and the limbs are terminated 
by suckers, hooks, or bristles. There are no differentiated 
respiratory organs, but respiration is performed by the surface 
of the body. The males are rudimentary, and are much smaller 
than the females, which are usually furnished with externa] 
ovisacs. The Epizoa are closely allied to the Coptpoda, and 
may, indeed, be regarded as parasitic Copepods, having the 
mouth modified so as to form a suctorial tube or beak, result- 
ing from the elongation of the labrum and labium. Within 
this are almost always two stylets or lancet-shaped mandibles^ 
used in piercing. The feet are often deformed by ag^ or 



ANNULOSA: CRUSTACEA. 



309 



. but arc primiiivcly nautor)'. Not only docs their dc- 

cnial hislof)' bear out this view, bul cases are knovm 

: Ltmaa) in which the males do not undergo retrognde 

Uii, but remain jienuanently in the condition of 

epods, 

division incltMles the single order IihihjvfklhirA, the 

ters of which are therefore the same ax those of the sub- 

f comprising various par^sit^s uiion fishes belonging to the 

I ZtTHUoi, Atlaherts, I'fnuulus, fac 
IDER i. IcHTHvapHiHiRA. — The members of this order 
tttcbe d in the adult condition to tlic skin, eyes, or gills of 
^^H when mature possess an elongated body, having a 
^Htts distinct head, and in tlie females usually a pair of 
^^Ejjrical ovivics, tiepeDilin^ from ihe extremity of the 
^^B Sonic adlierc by a sueloiial inoiilli, or by cephalic 
^^KCrf>Aa/una) ; othen arc attached by a suctorial disc, 
IPK at ihc extremities of the last pair of thoracic limbs, 
!t arc united together {JSriu/iiuita) ; whilst in others {OmAu- 
achmeni is effected by hooks at the free cxUeniilics of 
It ]>atr of thoracic limbs. — (Owen.) 
males are usually not attached, but adhere to the fe- 
of which, ftocn their miuh tmalter siie, they appear to 
re parasites, 'lie chief anatomical peciilianties of Ihe 
I arc the following : — The head is provided usually with a 
of jointed antenna;, and the body is divided into a ccpha- 
mx and abdomen. The alimentary canal consists of a 
, enlU:t,aiid intestine, terminattng posteriorly in a distinct 
The nervous Nystetn consists of a double ventral cord, 
embryo (fig. 63, a) is frce-swiniming, and is proviilcd 
inia) organs and locomotive apiwndiiget. 'Ihe two 




ilAMlaultofilMuia*. F.nlut^ {AfttrCtam) 

now alike, and the conversion of the active embrvo, 
into the swollen and defonned ailul^ must be regarded 
innlance of " retrograde metamorphosis." In Amhtro 
o 



SIO MANUAL Of ZOOLOGY. 

ftrtarum (1^ (t%), the primitive form of the younf; is a "Nui{>- 
lius;"* but a wholly diflerenl liirva, Tesein1>linf[ the Cyibfia 
stupe. Init with feucT liinl» and somites, is preiKircil within Uk 
Naupti US-skin, and in Hhcrntod by the TU[»t»Tc of the Game 

Okukk 11. KiiifocKi'KAi^.— The DAme RAisKipAala hu 
been proposed for another group of Crustatfa, which arc fixtd 
poroutic, and greatly deformed when adult ; but which are b- 
comotive when young, and which arc most nearly allied totht 
Cirripa/ia. The lan-ie are " Nauplitfonn," with an ovate mot^ 
mented body, an unpaired median eye, and a dorsal shield or 
cara[>ace. liie abdomen terminated in a movable cjudal fort 
and there is neither mouth nor alimentary canal. In thrrc 
Bccood stage (as so-caltcd " pupx '), the young of the A'^-v 
(ephala are enclosed in a bivalve shell, the foremost pair d 
limbs constinitc peculiar organs of adhesion (" pTchcDsile an- 
tenna:" of Darwin), the two following pairs of limbtarecaitoS, 
and six pairs of powerful biramoiie natatory feet are formed on 
the abdomen. There is still no mouth. The "pupx" do> 
attach themselves to the abdomen of Cnib(, P^cf/ieuue, uxl 
Hermit-crabs ; they remain aslomatous ; '* they lose all ihot 
hmbs completely, and appear as sausage-like, sack-shaped, or 
discotdal excrescences of their host, filled with ova ; from tkc 
point of attachment closed tubes, ramified tike roots, sink inlio 
the Ulterior of the host, twisting round its intestine, or beoooi- 
ing dilVused amongst the tac-likc tubes of iu liver. The only 
manifestations of life which persist in these nan ^ut uitnt n 
the series of retrogrcssivcly metamorphosed Crustacea are 
powerful contractions of lite roots, and an alternate expansxn 
and contraction of the body, in consequence of whidi wato 
Hows into the brood-cavity, and is again expelled through ■ 
wide orifict"— <Friu: Miillcr.) The branched roots of iKc 
Rhixoee^kala ap|)ear to be the homologues of Ui« "ceiocnt- 
ducts" of the Cirripcdia, and to be. therefore, really the 
antennje. 

Su)i-ci-«ss II. CiKRii>[ti>iA. — This sub-class includes, amoogK 
othera, the common Acom-shclls and the Itanuclea or Oook- 
mussels. All the Cirripettia arc distinguished by the fact, th« 
in the adult condition they arc permanently ^xcd to some 
solid object by the anterior extremity of the greatly metainor 
phosed head ; the first three cephalic segments beine mu ' 
developed, and enclosing the rest of the body. The lan-a 

* The name of "Kauplius" wat fivcn by O. F. Mnlter l» iba 
mMlcd ovate larva of the lov«i CrialiKM, u-Iiha m«<dlin fronul cy& bM 
wMmtit a true canpnce ; ami iliit name mif be convtnlantty CBployed U 
detignatA all the Urrsl rortni which agrtvia iheMchonciai. 



ANNUI.05A: CRUSTACEA. 



211 



free and locomotive, and the subsequent attachment, and con- 
version into the kxed atluli, is eflected by means of a peculiar 
secretion, or ceneni, which is disdurged through the antentuD 
of the larva, and b produced by a special cement-gland, which 
ia rctlly a iiOTtion of the ovaiy. In the CirrifK^ia, therefore, 
the head oi the aduh is permanentty fixed to some solid object, 
and the visceral cavity is protected by an articulated calcareous 
sh«!l, or by a coriaceous envelope. The posterior extremity 
of the animal is free, and can be protruded at will through the 
orifice of the shdL This extremity cxjtiMSts of the abdomen, 
and of six pairs of forked, ciliated limbs, which are attached to 
the thorax, and serve to provide the animal with food. The 
two more imporUnt types of the Cirriprdia arc the Acom- 
shelU {BalnHiJa) .ind the Barnacles {/j-/a<iu/tr). In iheformer 
the animal i.s Kcssilc, the larval antenna:, through which the 
cetnent exudes, being imbedded in the ccnac of ihc membran- 
ous or calcareous "basis'* of the shell. In the latter the 
animal is stalked, and consists of a " peduncle " and a " capi- 
tulum." The peduncle consists of the anterior extremity of 
the bodr, with the brval antennae usually cemented to some 
foreign body. The capitiitum is supported upon the peduncle, 
and consists of a case composed of several calcareous plates, 
united by a membrane, enclosing the remainder of the anima). 
Before giving a more detailed description of this singular 
and important sub-class, the following definition, as given by 
Owen, may be advantageously appcntlc<l :— 

" An/*'- chltlDOUt,or chilino.tcttiiMOiifc nib->r1iml*tKl, mntitir «ymine- 
Iricat Willi abonod wilcniiB ami eyrt. Afmti, prominont. coinpoatd of* 
labnm, palpv twonundiblevindtwapoinof maxillak TStfmr, aCtichMl 
to ihe denial lalcmal uufac« or th« tanp"*^*^ *'''' ■"' P*"* ^f multiarti- 
nbie. UnBout, icii^Froiu limhi. jiMmwi, radimoiury. Vowaiar 
•jntcn dlAkicd ; while blood. Btanchup, *hen pmcnl, jirucliKl la the 
imilar lalcnl pin of The mrface. Mo*( arc tirnnaplKoilitr : a Um have 
■tMH nallm«Mary, mate indiridiiili, ]xira>iiiniily alivhcd tdihe remalca. 
i\mil, pnlnKidirMal, multinnkulnle, alUcliol to lh« hinder end of lh» 
dldHMft. No onducti. MMamfTfhoai and in<^.i,'m.-ii/, mullint: in a 
patwaal namiiic altacbmtiit of the fnlljr-tlcvcloptd foiule or hctma. 
pbraditc iadividiul." 

As regards Ihe development of the Cirriptdia, the larva is at 
fitst a " XauiJius," with an tinscgmcntcd pyriform body, a 
median cj-e. and a dorsal shield or buckler. The abdomen is 
produced beneath the anus into a long forked caudal appen* 

S\ and there is a long spine over the anitv A month, intcs- 
e, and vent arc present, .^ftcr iieveral moults the young 
Nauplii l»ccome " pujKc "' (fig. 64). 'I'hc dorsal shield is 
(Dhlcd w as to fonn a bivalve shell ; the anterior limbs (anten- 



212 



MANUAL OF ZOOLOGY. 



nx) are transformed into prehensile oiguts; the two foUowbig 
pairs of limbs are cast off; and six pairs of strong, binmoK, 
natatory feet arc developed upon the abdomen. A p>ii of 
composite eyes are present, but there is no mouth. FuuUyidM 
pupse fix themselves by the prehensile antenns to rocks, dtift- 
wood, ships, Sponges, Cetaceans, Turtles, Cmstat^ans, or ens 




Fig. 64'—Loconiodvc "pupa" of B^lamui^ A Eye; ^audd Icudet; 
c Setigennu limbi. 

Jelly-fish. The prehensile antennae are glued down pennin- 
ently by the secretion of a peculiar cement-gland. The can- 
pace becomes, as a rale, the seat of definite calcifications, by 
which it is converted into a multivatve calcareous " test;" the 
mouth is developed, and the six pairs of natatory feet are coii- 
verted into long jointed " cirri," by which food is conveyed W 
the mouth, " The ' cement-ducts ' can be traced aS far as the 
third or ' disc-segment ' of the antenna. There the cement 
seems to transude and fasten down the disc ; soon both anten- 
niE are surrounded by a common border of cement, which 
gradually increases in extent after the metamorphosis. In the 
Lepas fauiatlitris the cement is poured forth in suffideni 
quantities to form, itself, the substance to which the peduncle 
of the adult barnacle adheres, and for a cluster of which ba^ 
nacles it constitutes a central vesicular floal," — (Owen.) TTie 
■ cement-gland, as shown by Uarwin, is " part of, and continu- 
ous with, the branching ovaria," and the cement-ducts open 
through the prehensile antennre. 

The form of the adult, as already said, differs consideraUy, 
but the two most important types are those presented respec- 
tively by the Sessile and by the Pedunculated Cirripedia. 

In the common Acom-shells (Balani, fig. 65, a) Uie anterior 
portion of the head is not elongated, but is fixed to the centre 
of a basal, membranous, or shelly plate, termed the " basis,' 
which adheres by its external surface to some solid body. 
Above the basis rises a more or less limpet-shaped, or conical, 
shell, which is open at the top, but is capable of being com- 
pletely closed by a pyramidal Ud, or " operculum." Both the 



AXNULOSA : CRUSTACEA. 



213 



shell itsdf and the operculum nic coin|>oscd of calcareous 
plates uMiall)' dlHenng from one another in shnpc, and dis- 
tinguished by special names. Within the shell the animal b 
fixed, head downwaids. The thoracic segmcnis, six in num- 
ber, bear six pairs of limbs, each of which consists of a jointed 
protopoditc and a much setpnenled cxopodite and eiidono- 
dite, both of which are ciliated, and oonsiitiite the :K>-c3tled 
"cirTi," from which the name of the sub-class is derived. 
These twenty-four tim— the "glass hand" of the lia/anas — 
ore in inccs.Mint action, bang protruded from the opening of 
the ihell. and ng.iin tctraclcd within it, constantly producing 
cumnts of wnter, and thus bringing food to the animal. There 
are no ^wcialised respiratory organs in the family of the Btiia- 
mttir. Batani sometimes atl^Q a very considerable size, and 
Salanut ftittaeut b largely eaten on the coast of Chili. 

In the Barnacles {LepadiAe, fig. 65, b) the anterior ex- 
tremity o( the animal is enonnoulty elongated, forming with 




nt.«V—UM»MnyarO>nf*4M a S«an* Cfirind* « BibnoJd, jSa^ow wiwAw. 
t PtdumlMt Uirlpcdi at X-tftiaii, Lt/ti •tttt.ti/mt. 

the prehensile antennx, the cerocnt-tlticts, and their exuda- 
tion, a long stalk or peduncle^ whereby the animsl is attacJied 
to some solid object. At its free extremity the pedimclc beats 
the " capctulum." which corresponds to the shell of the Bala- 
notds, and is composed of various calcareous plates, united 
loffcther by a membrane, moved upon one another by appro- 
priate mutclcs, aitd protecting in their interior the body of the 
animal with tt« appeiidages. The thorax and limbs resemble 
those of the Balanut; but " slender appendages, which from 
llteir position and conncaions are homolc^ciis with the 
bnnchiac of the hlghrr Crustivfa, are attached to, or near to. 
ihe bases of a greater or less number of the thomcic feel, and 
extend in an oppoxilc direction outside the visceml sac,"-— 
(Own.) 
All the Saianida are hermaphrodite, and this is also the 



214 MANUAL OF ZOOLOGY. 

case with most of the Z^padidte, but some extnur^nur 
exceptions occur in this latter order. Thus, in ■ome ipeda 
of Scalpellum the individual foiming the ordinaty shell b 
female, and each female has two males lodged in tniismK 
depressions within the shell. These males "are wry singutii 
bodies ; they are sac-formed, with four bead-like, rudimenlil 
valves at their upper ends ; they have a conspicuous intennl 
eye; they are absolutely destitute of a mouth, or stomach, or 
anus ; the cirri are rudimental and furnished with stiai^t 
spines, serving apparently to protect the entrance of the sac; 
the whole animal is attached like the ordinary Cinipedc, fiiS 
by the prehensile antennae, and afterwards by the cementing 
substance- The whole animal may be said to consist of one 
great sperm-receptacle, charged with spermatozoa ; as soon is 
these are discharged, the animal dies." 

" A far more singular fact remains to be told ; SeaipiBim 
vulgare is, like ordinary Cirripedes, hermaphrodite, \yiX the 
male organs are somewhat less developed than is usual ; and, 
as if in compensation, several shortlived males arc almost 
invariably attached to the occludent margin of both scuta. . . . 
I have called these beings eomplemetttal males, to signify thai 
they are complemental to an hermaphrodite, and that they do 
not pair like ordinary males with simple females." — (Daiwin.) 

Divisions of Cireipedia. — (After Darwin.) 

Order I. Thoracica. 

Compoff, eilher a capitulum on a pedicle, or on operculated shell villi 
s hiuis. Boily, formed of six thoracic segments, generally furnished with 
six pairs of limbs ; abilomen rudimentary, but often bearing oudal appen- 
dages. Ahulh, with lalirum not capable of independent moTCinenti. 
Larva, firslly one.eyed, with three pairs of legs ; lastly two-eyed, willi Bi 
pairs of legs. 

Fam. I. Balanida. 

Sessile, without a peduncle ; scuta and lerga (fonning the Mhr- 
culum) provided with depressor muscles ; the test of the nlns 
immovably united together. 
Fam. 1. ytrrueiii^. 

Sessile. Shell osymmelrical, with scuta and teica, which iit 
movable, but not furnished with a depressor muscle. 
Fam, 3. /jfcditit^. 

I'edunculated, Pniiincic flexible, provided with muscles. ScaU 
and ter^a. when present, not furnished with a depressor mnek 
Uther valves, when present, not united into a single immoT^^ 
case. 

Order II. Abdominal] a. 

Carapart flask-shiped ; body formed of one cephalic, seven tboruit; 
and three abdominal segments, the latter bearing three pairs of ciiii, bnl 
the thoracic segments being without limbs. Month, with the labrum 
Ereally produced, and capable of independent movements. Zarva, fiiitly 



ANNULOSA : CRUSTACEA. 



SIS 



J wUboBl «>tcrTul llmtit, at >n ey« ; luitjr binocnlar, wllliout 
: linlM^ bm with *1>daiuii»l ap|icn<ti>^c«. 

Okdkr 111. AroDA. 

Cam/mtf, mliic«<d lo lira xpiraic llircads, i«tviag for attaclimcni. 
B^ caoMning of coc nphalk, tevea thoracic, uDil tbrce abdominal Mg- 
ni«aU. all dMIitMe of cini. Mauili kucioiul. 

Geniit. Pnlnltfu. 




CHAFFER XXXIU. 

SUB-CLASS ENTOMOSTRACA. 



Sub-class III. Entomostraca. — The term Eniomestrata 
has liMU variously em|)loycd, and few authoriiKS include 
exactly tlie ume |[Toups of tlie Crusltt^ea undLT thtt name. 
By moot iIk diviuon ui Minply defined us including all those 
Cnulaita in wliich the tegmenta* of the lliurax and abdomen, 
takcD together, arc more or fewer than fouiiecn in number — 
the {Muastlic E^tfa and the Orripedia being excluded. By 
ProtesBor Rupen Jones the foUoning definition oj* the Entemos- 
traea has been given : — 

"Aninul a<)uatic, covered with a xhell, or carapace, of n 
homy conustency, fonned of one or more jtieces, in some 
gcncre Tc%enililing a cuiroM or huckler, and in uthcrx a bivalve 
ihell, which coinjiietely or in great p.iit envelops the body 
and Itmbt of the animal. In other genera the animal is invested 
with a multivalvc carap.tce, like jointed plaic-armour ; the 
braachiac are attached cither lo the feel or to the organs of 
laaalicaiion ; the hmbs are jointed, and more or less sctifcrous. 
Tiut aninuU, for the most pan, undergo a regular moulting 
or change of Khell, as they gn>w ; in some cases thb amounu 
to a tpecin of trantfonnaiion.'' 

The Eiilfimcttrafa are divided into two great divisions, or 
" legiooSf" the L^fkyn'poi/a and ihc Jtran^Ai'fl^/a, with which 
llic tndcr Mrr^stemala may be conveniently considered. 

DivtaioM A. LopHVRoPOUA.— 'ITif members of this division 
powcas few branchix, and these aie attached to the aiipen- 
dagea of the mouth Tlic feet arc few in number, and mainly 
UMcrve looomooon ; the carapace i.i in the lorm either of a 
ihidd [iTOtccting the cq)halolhoTax, or of a bivalve shell 
cnclosiitg the entire body, 'llic mouth is not nictorial, but is 
furuished with organs of mastication. 



ai6 



MANUAL OF ZOOLOGY. 




This division comprises the Ivro orders Ostraetda 
C^fepoda. 

Orosk I. OsTRAcoDA. — Small Crustaceans having ihe entire 
body enclosed in a shell or<:arapace,whiirh i:i<:onii>otiedoriva 
valves united along ihv biock by a membntnc. 'live bnuichii 
arc attached lo the posterior jaws, and ihcre are onl)' tw« u 
three pairs of feet, which subserve locomotion, but are not 
adapted for swimming. A distinct heart is sometimes pretcni 
(CyfiriJina), but is more usually wanting (Cjfrh and Cythm). 

Little is known of the development of the Osiramfa, but ihr 
young of Cypris are said to be " sliell-bearii^ Nauptius forms ' 
(Clans), nossessiiig only the three anterior paint of tiinl«, lot 
protected by a bivalve iliell. A.t in other Nauplii, the third 
pair of lirobs, though now locomotive, are ultimately traiu^onntd 
mto the mandible:*. They p.iss through MivemI stages, wiili 
complete moults before arriving at scxtul maturity. Hit 
Cythtritlts, on the other hand, have at birth the tv-o pain cfT 
aniennx and t«-o pairs of jaw^ with three pain of rudioKiitvy 
abdominal limbs. 

Tlie order includes the Cypri4es (rig. 66, a), which are of 
sbnost universal occurrence in frc^h watei. 'ITie cgisison 




^/. JS^, 






Tf, 6(.— Prah-mU> Enumoitnai. a Cffnt irti-ilrittti 1 1 ritfM* 

Cyprh is completely protected from its enemies by a bivalw 
carapace, which it can open and shut at will, imd out of wbidi 
it can protrude its feet, l/icomotion is mainly effected by 
meaiiK of a jiatr of caudal appendages. The Cyprit is ex- 
tremely prolilic, and a single impregnation appears to but the 
female for its entire lifetime. It appears also, that the youac 
females, produced in this way, arc capable for some gencralioM 
of producing fresh individuals without the influence of a itule 
(putbenogeneus). 




ANN'ULOSA: CRUSTACKA. 21/ 

OitDUt II. CorsPODA.— StniH Crustaceans, having the head 
and thorax covered by a nrajuicc, and fiinitshed wiih five 
pairs of nataioT)^ feet Unially there arc two cniidnl locomo- 
tive appeodagcs. A distinct h«art is sometimes abtient (as in 
the Qaefiiiitf), but is sometimes prc&cnc. Both marine and 
Cresh-mUcr Copcpods are known. 

The Urvae of the Copepods are Naupliifonn, with unjNiired 
tya. three pairs of limbs (t\\e futtire antenna: and manditiles), 
and t«'0 terminal seta;. Next the nuxilbe are |>rodi]ced, and 
llien thicv other pairs of limbs (the foot-javn and the two fiODt 
pairs of natatory feet). At the next moult, the larva assumes 
the Cyihpi form, but has at lirst much fewer limbsand somites. 
Ir ilic Cjdofs ffig. 66, <-), which is one of the commonest of 
tbe " Water-fleas," the ccphalothorax is protected superiorly by 
a canpace, and the abdominal Mmiitcs are consiiicuoiu. In 
front of t)te head i» situated a single brge ere, behind which 
arc the great antenna: and the antennules. JTie feet are five 
pairs in number, each consisting of a proiopoditc and a seg- 
mented cxopodile and endopodite, usually furnished with hairs 
utd forming an efficient swimming apparatus. The young 
pus through a metamorphosis, and are not ciinlile of repro- 
ducing the species until after t)ie third moult or change of 
skin. The female Cydefi carries externally two ovisacs, in 
which the ova remain till they are hatched. A single congre&s 
with the ntalc is apjuuently suBicicnt to fertilise the female 
for life. 

The C^epeda, or ()ar-footed Crusuceans. arc all of small 
tiie, and are of common occurrence in fresh water in all parts 
of F.urupe. By good authorities the Mihyvfklhira are re- 
garded as merely Cafitpeda peculiarly modified to suit a life of 
pansitixm. 

Division R. Branch iopoi>*. — The Crustaceans included in 
this (liviHon have many branchiae, and these are attached 
to the legs, which arc often numerous, and are formed for 
sirtmmiiig. In other cases the legs themselves are t!.iilened 
out so as to form branchiae The body is either naked, or is 
protected by a carapace, which may enclose either the entire 
body, or the head and thorax only. The mouth is provided 
with ocgans of mastication. 

The Braiuhutpoda comprise the QaJeara, the PhylhpoJa, 
and probably the TrUMta, though this order departs in many 
respects from the above definition. The MfTi)s(i}mata may 
be considered along with these, though these, too, are in many 
respects ]>cculiar. 

Okukr I. Ci^tracERA. — The members of this order arc 



2l8 



MANUAL OF ZOOLOGY. 



small Cmittaceans, which have a dixtina hcacL and hat-el! 
whole of the remainiler of the body enclosed within a bivoln 
carapace, simtiar to that of the Onraada. llie feet aiclcv 
in number (usually four, live, or six pairs), and are moulf 
respiratory, carrying the branchia;. Th-o paire of antennae are 
present, the larger pair being of large ^xe, branched, vA 
acting as natatory organs. The Ctadaara quit the Qgg with the 
full number of lirabs proper to the adult 

In the Daphma pu/ex (fig. 66, i), or "braitchcd-honcil 
Water-flea," which occur commonly in our ponds, the body 
is enclosed in a bivalve shell, which is not ftimi&hcd with a 
hinge posteriorly, :ind which opens anteriorly for the pfoini!>ioD 
of the feci. The held is distinct, not enchased in the can- 
pace, and carrying a single eye. The mouih is situated on the 
tinder surface of the head, and is provided with two mandibtn 
and a pair of inaxillte. The gills are in the fonn of pinto, 
attached to the five pairs of thoracic legs. 'I'hc males an 
very few in number, coni]>are>l with the fcm.iles, and a single 
congress is all that is requirctl to fertilise thu female far life 
Not only is this the case, but the young females produced from 
the origin.ll fecundated female appear to be able to bring fottb 
young without having access to a male. In this way the inAi- 
ence of a single fecundation appears to be transmitted thmu^ 
several generations. Two kind.s of eggs occur in DaphtM. 
In the first of these, or "summer eggs," the ova (from ten to 
fifty in number) are deposited in an open space between the 
valves, and are retained there till the young arc ready to be 
hatched. In the second of these, or "winter eggs," the owa 
(generally two in number) arc placed in a peculiar receptacle, 
which is formed on the back of t)ie carajiacc, and is callod the 
" cphipiiium " or saddle. After a time the e|ihi}>pium is can 
off, and floats about till spring, when its contained eggs are 
hatched by the wanner temperature of the water. 

Orbkr II. Pitvu.OPODA. — Cruitaaa, mostly of small sire, 
the carapace protecting the he.id and thorax, or ilie body 
entirely naked, l-'eet numerous, never less than eight jiaiis, 
mostly foUaccotis or leaf-like, branchial in function. Ilie ejes 
aomclime:! confluent, sometimes distinct and sul»-|>eduncubte. 
There are two homy mandibles without palps, and the first pair 
of feet are oar-like, with sciiform termiiul apjwndngcs. The 
remaining feet are branchial, an<] adapted for swimming. Tke 
I%yllopods undergo a metamorphosis the youngest forms being 
"Nauplii." In jiHa/ia, however, which is the only tnshoe 
Phylli>]iod. " Zoca-slages " arc supcmddcd .is wxrlL 
The Pkyihpoda are chiefly interesting from their alfiniiy 



Sniiy to I 



ANNULOSA : CRUSTACEA. 



319 



E; Trilobiies. In the typical genera Limnadia and 
boJy ii jwotecied by a carapace, which ih bivalve 
in the bxaxw atui khicldlike in the latter. In Limnadia the 
carapace covers ihc greater jmui of the body, and opens along 
the ventral margin. There trc from 18 to 30 jiaira of mem- 
ceou8 and resi>tratory feel. In Afm the caraiMcc it 




ric- *f.— PliT<are^ r>iry Shrimp (C*i»wii/4iA.i di^Jtimii-ih-^r li^inL 

lypeiform and covers a portion of the abdomen; and there 
sixty pair of feet, of which all but the first jiair are 
ilijiccouiL jifiut is pe^ous, fre«h-water in habit, and often 
fbuod in great numbers in po<^ and ditches in Europe. The 
diflercnt species of Vranthipiu have the body unprotected by 
any carapace, and axe found in ponds and swamps in various 
parts of the world. The various " Jirinc-shriinps " {Arltmia) 
nre found inhabiiing the brine-pans Ja salt-works, or occur in 
uli-Ulces in both hemispheres, being e^jiedally abundant in 
lireat Salt Uke in Uuh. 

Okdkk 111. TfULoaiTA.— This order is entirely extinct, none 
of its members having survived the close of the Pahconoic 
period. It is probable that the Trilobites should be placed 
near the Pkylkfoda; but their exact position is uncertain, o^ 
with one cxccptiofi, no traces of any appendages of any kind, 
except the labrum, luvc hitherto been discovered in any Tri- 
lol>it«. 

TbcbodyofaTrilobite(fig. 68)was covered with a "crust," 
or cxoslcclelon, which shows more or less markedly a division 
into tliree longitudinal lobe-f, Irom the presence of which the 
of the order is derived. The shell is composed of a 
:ic shield, a certain number of free and movable thoracic 
and a caudal shield, or " pygidium," the rings of which 
lOre or less completely anchyloscd. On the under surfecc 
if the body nothing has hitherto been discovered, except the 
" hjrpostoroe," or " tabrum," which was a plate placed in front 
of Ibe mouth. No traces of ainbulatwy or natatory Iimb«t, of 
IHanchia^ or of antennii:;, have ever been discovered. The 
ica, wbco present, are compound, and usually settile, but 





230 



MANUAL OF ZOOLOCV. 



are sometimes supponed upon projcding procemes. It 
generally been supposed that the body or the Ttilohite occt 
the mcclmtn tobc of ihc ciusl. commairing with the " gUbcQi* 
in Erani, and terminating with the " p^idiuin " behind, whiUt 
tkcsxial lobes protected a scries of delicate respiratory fwt; 
but this view is doubled by many authorities, and the question 
is one which wc have at prescnl no means of deciding. Qoiie 
recently, however, a specimen ofa Trilobile has been tlitcovend 
jn which it is SMd that the bases of the legs were distinctljr 
recognisable. I'he s[iecimen in question wax an AiapkMs: 
l>ul the great number and enccllcnt jircnervnlion of 'I'rilobilea, 
as A general rule, render it hightjr probable ihjit in most aan 
the limbs were destitute of a chitinous exoskeleion, and were 
therefore incapable of being preserved in a fossil stale. Ac- 
cording to Spcncc llate, " (he young of the Trilobitcs ut of 
the Nauplius form." 



\ 





l]M()ru(ff)l (( fifti chatk, rncludtng tlia (ivrnW (^); rr tmtUiMtrt, 

The cqihilic ihidd of a lypicjil Trilobite ii more or tc« cnmelettlT , 
teiDKircuW (lig. 6S. 1), ■nd ii compOKd of »ccntr*l xiid at iiro Ulcid , 

K'c««i. of which Ihc two Utlcr may, or may not, be uniicd tocclhcr bl 
>nl of the (bnner. 

The i»«li>n patlion I* luunlly tl«v*ted ibot* the reinainiler of lb( 
cephalic khleld, and is oiled ihr "i;lnbcll«i" it prolfcttd ihe let^ c(| 
iha woniach, *nd U usiuJIr divid«>1 into riom three to four lob«a by l«t«nl [ 
poove%i At oacli side of the glabella, and cantioiicnu uiih Jt, ii k bmII ' 
semiirirculiu area, colled the "fixed cheek." The tlabeUa. villi (he'fcatd 
checks" U Kpiruicd from the Ifticnl portions of ilic cephalic shield— 
termed the "movable' or "free thcelit" — by ■ nceuliar nlore or lint 
el diviainn, whl-;h l» known i* Ihe " hclal tulure, aai b (|vile unknon 
•mongit recent ('rtuUtiu, cicrpi for a £Unl Indication >n lltc LimuJmt, tod 
more or Icm cluulilful Iracct in certain other form*. The moTablc ckeckl 
bvar the €}*», nbtch are generally cmoentic ur renifonn in ihap^ MC 
mrfly pedunculiUod, and coniiit of ui ij^^gaiion of ficeli covertid by i 
tliin oofne*. The bdal iiuurc* inty jom one knolbei in (rant of ' 



flnl of ^^^ 




ANNULOSA : CRUSTACEA. 



331 



tjliiVclh— in wfakh cue tbe ftce diMkt will (oim » single piece— mr Aef 
m*f cut ihc intdkir naiyln of Ihc iliteld KCantely— in wblth fue tbe 
free dkeefct mil be diKontlnuoui. Th« pottcnor ftnjjlet of ihe free check* 
■M often productd (nio lon|> tplnci. 

Bchkxl the ofjihalic thidd comn llie ihorax, compotrd of ■ ii«ri«blc 
nuBbar of Mgnwiiti, which am nol widered [ogellin, bal an ap«ble of 
lite vatiam mfum one Mioihet, lo as lo allov the onlnial 10 roU itwir up 
after the ■umaei of a woad4aiuc, or hcdschoE. The lhc>Tu i» laiudly 
Mw wtf y trilotwOL and cMh thorax-iine ibowt the mmc uilobalian, bciiij[ 
cMnpwed ol a coHfal, more or teu xlmn|^y convex, |unlioii, called the 
" a»»." awl of iBo fiiiict Mile'Icihct, oiled the "picutic." 

Tbe " |iyi,>iilluni," or "lail," ii ntualljr iriUlicil aW nnd, liter the ihanix, 
COWilw* of a nKdian kiit anil of a Riaiginal litiil^ Ihc co^lilu^iIit■n uf the 
«llolc out of anchxlosed Mpneoti iong ihown bjt the euitcnoe of axia] 
aad plennl groovcf. 

Okdek IV, Merostouata. — The merobera of thU order 
are Cruifa^m, often of gigantic site, in which the moulli is 
furnished wilh mnndihles and Rioxillie, ihc tenninnlions of 
which hccoim: wnlkin){ or KwimminK feet, nnd organs of pre- 
hension. 

Thic order oomprises the recent King Craljj, and the extinct 
Plrrj^t and Eurypteri. 

StiB-oRDEK I. XiPBosuRA. — " Cruslacea having Ihe anterior 
BcgiDenta wrided together to fonn a broad conven buckler, 
upon the donal nimce of whicJi are placed Ihe <.-om|>ound 
eyes mkI occlh^ the fonner sub-ceniniily, the latter in the 
centre in front. The mouth is furnixhvd uritl] a small labrum, 
a rudintcnlaiy metastoma and six pains of appendages. Pos- 
terior segments of the body more or less free, and bearing 
npon their ventral surfaces a scries of broad lamellar appen- 
dages ; the telson, or terminal segment, ensifonn." — (Heniy 
Woodward.) 

1'he .Vf/^c/Krii include no other recent forms than ihe 
I.imnli (Kinjt Cralni, or Horse-t-hue Crabs) (fig. 69), 'fhey 
ne djstjngui^hed by the possession <A six fairs of <he!alt limi't, 
fiaud nuud thr mnulh, having Ihtir base» spinous and officiating 
as jaws. Six other pairs of foliaceousaiigtcndjigcs are attached 
10 the abdomen, and the Ust five of these carry branchiic. 
The body, whkh is often of grest size, when viewed from above 
exhibits a divi.tion into three portions: — (t) .An anterior semi- 
drtiibr iibidd, which carries two compound and two simple 
eyes ; (>) a ]x>sierior, irreftularly hexagonal shield, which covers 
the abdomen ; and (3} a long, tword-iilte telson, anicuhted to 
the dorsal bticlclcT, and giving the name to the siib^order. 

The chief features, therefore, which characterise the Limuius 
are as follows t — t. The possession of six pairs of appendages 
wfikb arc placed round the mouth, have tlicir bases spinous, 




222 



MANUAL OF ZOOLOGY. 



act as jaws, and have their free extremities developed into 
claws; 2. Thepossessionof six abdominal pairs of appendflgO) 
expanded for swimming, and carrying the gills ; 3, The posMt- 
sion of a semicircular buckler, covering the cephalothcnax, and 
carrying the eyes upon its upper surface ; 4- The possessiofL <i 
a second buckler, or "operculum," covering the abdcxnea; 




Fig. 69.— Xiphmura, Limtt/ta fofy^kt- 
jif«u^ vicwcrtfmm below, fl^ cephalic 
ihicliJ cATT^'in^ ihr i«t^ilc ryri upon jfi 
upper surface ; p " Operculum,'^ covei^ 
inE ihcFCprnJuciiveDriEant : ^BraDclii*! 
plal«: d (Hr^l pair dF anicnn^ fuiKn- 
niJo) cfldinR in chtlir. B«li>w (hne in 
the JipcrluTF of ihe moulh KurYtiundcJ 
by ihc 'piny b^^cs nf the remiininj^ five 

Cain ur appendices uhich arr rr^ardcd 
J" WrK'tdward a^minp i^^pecrivcly,rrDin 
bcfnic bhifli'^'Jrdfi ihe £rral anlennz, (he 
nundiblei. ihe iij*-t nuiiJIv, ihc second 
nuxillE. andapairgfmaxiULpcdet- AM 
hivc ihtir eitremiiie* chelate. 




F!;. TCv-^Euryptctida. PtnTfvha Am- 
giutii. TtMored (after H. Windwvd). 
e c Chelale anienn^r : a n £ye«t vtuaiid 
x\ Ihc Atirciior matjEin of lheran|nct; 
Mr m The nundihlea^ht ftnt ud ■>- 
cond Diajiilbc ; m ■ The nuxDItpfdei ; 
the baul mareiiu of th»e are Bcmted, 
and are drawn as if weq thfouch Ux 
mcUitDma or poM-<^ plate, wUtl 
uTve.4 aialowerbp. Imioedianly bp 
hind thii is >ccn (he opercuJim □* (^ 
rucic plare which co*cn ibe m latr 
riorihoracic somitei^ Bchiikd tUt vt 
live thonck and five abdocniBiJ ■avM^ 
uhj laitlr there it the IcIkh {fy 



5, The presence of a long, sword-shaped telson, or tail^ne^ 
articulated to the dorsal shield. 

The larval Limtdus docs not possess the ensifomi post-an^ 
spine of the adult, and is further stated to show a decided r^ 
semblance to the Trilobites. 




ANNULOSA : CRUSTACEA. 



333 



TTic KiDg-cmbs arc found in the Indun and Japncse Sea^ 
on the coasts of Nonh America, and in ilie Antilles. Thty 
s<nnetinies attain a large sixe, and both the eggs and the flesh 
are eaten by the Malaya. 

SUKOKOCK 3. EvRVPTKitiRA. — "Crwiitncci ""itli nuiiierous, 
free, thcncici^abdominal segments, the hrel and .sccand (?) of 
wi)icli bear one or more broad lamellar AppcndAt^es upon their 
ventral surTacc, the remaining segments being devoid of ap^wn* 
dagcs ; anterior rings united into a caxapacc, bearing a pair of 
larvgU cj-es (Mrffi) near the centre, and a pair of large, nwur- 
ginaJ, or utxentral eye« ; the moutli furnished with a broad 
post-oral |ilate, or nutastoiHa, and five jiairt of movable appen- 
doces, the piistcrioT of which fonn great juiraming-feel ; the 
tetoon. oc terminal segment, extremely variable in form ; the 
iousuraentcharacicristically sculptured- " — (Henry Woodward.) 

1 nc £uryp(eruia arc all extinct, and arc entirely confined to 
the FalKoioic period. Many of them attained to a compara- 
tively gigantic «Jte; PteryfiiUm AngiUus (fig. 70) being sup- 
posed to have reacheil a leniftli of prolutbiy six feet. In their 
characters (hey inresent many lan-al features ; resembling the 
larvic of the Draifiwlii especially in the fact that all the free 
somites of the abdomen (except the two anterior ones) were 
totally devoid of appendages. 

^^HHIK IV, ]ktALACOST«ACA. — Tlic CruslotM o( lhi« suh- 
r dus an distinguished by the {>oM(c«(ion of a Kenerally drfimtt 
I number oi bocTy-segntents i seven somites ^oing to make np 
the thoraut, and an etjunl number entering mto the composi- 
tion of the abdomen (counting, that is, the telsoo as a somite). 
The Malaeoslraca aie divided into two primary divisioni^ 
termed respectively the lidritr^htkalmnta and iJie Pmhphthal- 
Mott according as the eyes arc sctstle, or ar« supported upoD 
eye^ulks. 

Dtvisioii A. EuKioPHTHALiiATA. — lliis division compriMi 
thoie MaiMottraai in which the c\'oi arc sessile, and the body 
it moMly iMt protected by a carapiirc. It comprises the three 
Orden, Lamtdip^a, hopoda, and Amphi^ifda. The e>'es are 
gncRLny compound, but sometimes simple, and arc placed oa 



CH.APTER XXX!V. 
MALACOSTRACA. 



234 



MANUAL OF ZOOLOCV. 




the nd«s of the head The head is almost aiways distinct 
from ilie t>ody, jui<I the mandibles arc ohen rtimishcd with a 

1>iil|>. 'r)pi(.'ally there are seven jiain of feet in the adult 
iciici: till!, diviiiion is called THrndttapoHa by Agassiz. la 
ccnain Isopodit ( Tanais) alone is there a carapace. 

OxoER I. l^cMODirooA. — 'I'hc Lamedifvda bm small Crt» 
taccans, uhich arc distinguished amongst the E^ri^^kalmaU 
by the nidimcntaiy coodition of the abdomen. Tlie fini 
tlioracic s^mcnt is amalgamated with the bead, and the linln 
of this segment appear to be inserted beneath the head, or, at 
it were, bcuwili the throat (fig. 71); hence the name given 10 
the onier. The reipiratory organs are in the form of two oe 
three pairs of membranous vesicles attached to the sq^nKBa 

of the thorax, or to the 

bases of the leg*. TV 

last pair of fret are etiha 

i^^^ S " /f^-oJ* ^^\^ inserted at the end of iht 

H^^^ftJ^ ^1^^ 1 Inst somite, or are followed 

'^ by not more than one m 

Km— UaiJ^ini*. cyn/fajUMw. two email segments. There 

are four setaceous ontcnnx, 
and the mandibles are without palps. The body is gcae- 
rully linear, of eight or nine Joints, but is somciimcs oviL 
The feet arc hooked. The Lsmodipoda arc all marine, aaJ 
one section of the order comprises parasitic Cnistaceaas. of 
which the Whale-louse {Cyamm Ofi) is tltc moM fatiitliar. 
The entire otder is now generally regarded as being mod/ 
■ section of the Amphip^it. 

Okdkk II. Ampiiii'ijda. — The members of this Older te 
semble those of ihc preceding in the nature of (he rcsptniion' 
organs, which consist of membranous vesicles attached to the 
bases of the thoracic limbs. The first thoracic segment, hot- 
ever, is distinct from the head, and the abdomen is well 
developed, and is composed of seven segments. There m 
seven pairs of thoracic Kmbs, directed partly forwards, and 
partly backwards, the name of the Order being derived froo 
this cinnimstance. As in the Laiwdiftita, the heart has Ifcc 
form of a long tube extending through the six segments follow 
ing the head, and having the blood admitted to its interior bf 
three pairs of val\-ular fissure*. The three posterior pain of 
abdominal limbs arc bent backwards, and foim. with the iri- 
son, a natatory or saltatorial tail. The yoting Anuihtpod 
ai:<iuires its full numt>er of negments and limbs bcron ill 
liberation from the egg ; and as a rule the ^'oung undergo 
little or no meumorphosis in nacfaing muuntjr. 



ANNULOSA: CRUSTACEA. 



335 



the Amfhipoda are small, the "Sand-hopper" (Talitrus 
bcutla, fig. 71) Bi»d the " Ircsh-walcr Shrimp" (Gummarus f^!ex) 
beiDg two of the commonest forms. The Sa»dh(i|ipcni and 
Cuninari swim on their side when in the water, and the fonncr 
leap with great activity on land. 




Ft£- 7*. — Anphipodft- Tlic Suid^hopps. T*Iilrwt tcmsit>, wiiv^fL 

OSDXR III. Isoro[>A. — In this order the head is always dis- 
tinct AtMn the segment bearing the first pair of feet. The 
Kwiralory oigans arc not thomcic, as in the two preceding 
oraers, but are attached to the inferior surface of the abdomea, 
B& consist of braDchix, which in the terrestrial species are 
imeaed by plates which fold over them. The thorax is com* 
pMcd of seven scgroents, bcarinR ncven pairs of limht, nhich, 
■n the femaleSi have marginal jilaien atl;ic:hcd to their bixes, 
*>n] Krving to protect the ova. The number of segments in 
"watdomcD varies, but is never more than seven. The eyes 
W tm in nuRibcT, fomcd of a collection of simple eyes, or 
WinciiiDes truly compound. The heart is sometimes an clon- 
EMed tube, vriih three pairs of lissurcs <ns in the AmfiAipada), 
■MnctiBMs short or si>lieTical, removed towards the abdomen, 
*nd «ilh mote or fewer fiisuies than the above. The young 
(■oimd is dev«h)ped within a Larval caembrane, destitute of ap- 
icndiges. Al^er :i time this mc-mhrane bursts, and libcratex 
1^ rouDg, which Te»eint)l» the adult in most respects, but 
panesBca only six instead of seven pairs of limbs. Of the 
BoiAws of Uiis order, many arc ai^iiatic in their habits, and 
*R oAco parasitic, but others arc tcircstrial. 

By Milne-Edwards the hofoda are divided into three sec- 
liew, lenned respcctiwly, from their habits, the jVatat,iria/, 
Stdmtary, and Cuntrial Isopods. In the Natatorial /s^fda 
Ac extremity of the abdomen and die last pair of abdomiiul 




236 



MANUAL OP ZOOLOGY. 




L 



le^ are exjxinded «> an to fonn a smtnmmg-tail. Sorrr 
this section »n: parasitic upon various lisltcs (Cym^Aoa), u.n. 
OthL-rs arc found in ihc sea {Sf/iaroma). In ihe SedaiUrj 
/to/mda the animals aic al] parasitic, wiih short, incurved, 

booked feet '{"his tecim 
indudu the single Cirni''--^ 
the Bepyridts, all the i] 
of which live patasi:. 
dthn in the gill-chuii 
or aiucbcd to tlte iimtiu 
Burracc, of certain of the 
Decapod Crtulacta, tnch t> 
the Shrimps {Cra>^9ius)iaA 
the Palamonti. 

The Curs&riaJ, w ran- 
riing, li^p^ds mostly !i>« 
upon the land, and art 
therefore destitute of swim- 
raing-fcet llic most binil- 
iar examples of this tectioe 
are the common VVoodbcc 
{Onuait). Here, also, be- 
long! the little JJmimit 
tetmraiu, so well known for 
Ihe dcstrtKtion which it pro- 
d«c« by boring into tk 
wood-wOrk of [uen and other structures placed m the *«. 
Other wcll'known Isopods ore the Watcrslatem (^/aVu) rf 
fresh waters, the Rock-tlater« (tigia) of almoiit all coacti, Ik 
Box-slaters (/i/oMai), the Shield-ilatera {CatiiJiiia), and ibe 
Chcliferous Slatt-rs ( fanais). Theie last arc remarLabte M 
bein^ the only Isopods in whidi there is a carapace. Ttt 
lateral pans of the carapac*: are highly v.-i.tcular, and reqiin' 
lioD is effected by these, and not by the abdomiiial fecL 

Many Isopods undergo an extensive mctamorphoMS. "h 
some Pidi-lice (CiMofAou) the )-oung are lively sw-tmmcn;ud 
the adults are stiff, heavy, stupid fellows, whose short diflfii^ 
feet are ca|uible of little movcmenL' In the Bofxrida the 
adult females are unially blind, the antennje are nidimentanr, 
and the abdominal appendages from natatory become re|in- 
lory organs. The males, on the other hand, arc dwniicd, nd 
sometimes lose all the abdominal api>endnf[es, and all Inuxs of 
•esmentation ; until wc get forms which, like Cryptmismt fh- 
narwidei, " would be regarded as a I-'lal-worm rather than « 
Iwopod, if its eggs and young did not betray its Cntsucon 
MtuK."'— (FriU Miillcr). 



PI» T>-limodi. W*«l-na<0«inuX 



ANNUIXISA : CRUSTACEA. 



j»7 



Division B. Podophthalmata. — The tnembera of this di- 
vision hxvc compound ey«s supponcd upon movable stalkx or 
(xdundes, and (he body is always protected by a ceptulotbo- 
rack canpace. Mott o( the Ptkophlhaima pus through Zoca- 
ttMges in their development. It comprises the two orders 
Sl^mafeda and Dfwfoda, of which the latter inchidcs all the 
highcU and moct liunilLai examples of the class Crusiacta. 

OktiKK 1. Stomapoua. — In this order there arc gcncrally 
fiom six to eight pairs of legs, and the branchix, when present, 
are not cndoMd in a cavity beneath the thonu, but are either 
■uspended beneath the abdomen, or, more rarely, are attached 
to Ute thoracic legs. The shell, aUo, is thin, and often mem- 
branous. From all the pret^dlng orders the S(oma/w/a arc, of 
course, distin^ixhcd by the poneisiou of pcduncuhic eyes. 
The devdopmcRt of the St^mafioda would apjKar to be by 
means of "/oex." 

All the Siomapods are qtarine, and the Locust Shrimp 
{SquiHa mantis) iiuy be lalcen as a good cxainplc of tl)e order. 
In this Crustacean tlie carapace is small, and the posterior 
half of the thonu i« unprotected. Several of the anterior ap- 
pendage* are develoi>cd into powerfully prehensile and hooked 
KCt The branchia: arc anachcd to the first live pairs of ab- 
dooina] feet The three posterior thoracic and the abilominal 
appendages are in t)ic form of "swimmerets," and the tail is 
expanded into a powerful f\a. Besides the Locust Shrimps, 
the order include! tlie GlaM Shrimps {£ruAtAji) a»d their 
■Uies, and the Opossum Shrimps (Afyiis). 

Ordkr II. DacAPODA- — 1'he members of thi.t order ate the 
nKwt highly organised of all the Ctuitacea, a.s well as being 
tboic which are most famili.irly known, the Lob^^terv, Crabs, 
Shrimps, &:c, being comprined under this head. For the most 
part they are aquatic in their habits, and they are usually pro- 
tected by stroiig, resisting shells. There is always a com- 
plicated set of " (jnathitcs," or appendages modified for mas- 
ticatory purposes, surrounding; the mou^ The ambulatory 
feet are matie up of five pairs of legs (hence the name of the 
order), the first pair— and often some other pairs behind this 
— bcmg "chelate," or having their extremities developed into 
ntppjng- claws. The branchix are pyramidal, and are con- 
tained in caviries at the sides of the thorax. The campace is 
Urge, covering ihe head and thorax, and the anterior part of 
the abdomen. The heart of the Dftapoda is in the fomi of a 
more or lest quadrate sac, furnished with ilirce pairs of valx-ubr 
openiitn. As r^ards the development of the Decapods cnor- 
aou> dilTereiicea obtain, even amongst forms very closely 
lUied lo one another. 



i2B 



MANUAL OF ZOOLOGY. 



The De^apada are divided into three tribes, termed 
tively the Maervra, Anemura, and Bratiyura, and cbuadci-^ 
ised by the Dalurc of the abdomen. 

Tribe A. Macrura. — The " Jong-Uilcd" Decapods ine 
in this iribe are dititinxutslied by (he possession of a wi 
veloped abdomen, olten longer than the cephalmharajc, dx 
posterior extremity of which forms a [Wwerfiil natatoty orpo 
or caudal dn. As regards ihc dcvolo[iment of the Matryn, 
most appear nt first in the form of " Zocie ; * but there is little 
metamorphosis in the common Lobster, and there is said to be 
none in the Cray-6sh {Aitattis fifniiaiiih) and in one of i 
Land-crabs (Gtfarcinus). Fritz Miitlci, again, has sho 
that the primitive form of one of the Shrimps (Pmftti) is I 
of a " nauplius." This section comprises the Lobster, 
fish, Shrimp, Prawn, &c., of which tlie Ix>bster may be taken u] 
the type. 

In the Lobster (fig. 74) the somites of the head and Ihceu' 
are amnlgamated into a single mass, tlie " cephalothom,' 
covered by a carapace or shield, which b develo»ed from "thej 
lateral or epimcral elements of the fourth cephalic ring, i4iie~ 
meet along the back, and give way preparatory to the mouU 
Tlie tergal elements of the thoracic rings arc not developed ) 
either Crabs or Lobsters; when these rings are expoud 
lifting up the cephalothoracic shield, the epimer^ parts alo 
arc seen, conver^ng obliquely towards one another, but 
joined at their apices," — (Owen.) 

The first segment of the head bears the compound eye«, 
which arc supjiorted upon long and movable eye-stalks 
peduncles. Behind thne r^mc two pairs of jointed tKttll 
organs, die larger called (he "great antennic" (fig. ^i,sa),< 
smaller the "antennules" («). The mouth is situated 00 1 
under surface of the front of the head, and is provided I 
before backwards with an upper lip (" labnim"), two " 1 
btes," two pairs of " maxillx," three pairs of " raaxillipede 

* The young Decapod, in moll cawt, icavti Ihe ccg in a Iwnl Uxm 1 
difTercni to the adult that il wai originilly deicribcdu a iliilinct 1 
under Ihc nimc of Zw). tn ihii )la|{c (fie- T^> t^' Ihoiidc k 
with the five pain of Icgi proper to the odnll kie dihci wantin 

Suite tiidicnentuy. The ibdomcn and mil are without apficn ~ 
10 Iftticr a coiDTxwed of > single pir<c. The foot-Jiwx are ia I 
natsloiy forked lc«t, and (he mandible hot no pa)|\ IjiuIv, t] 
bmnthiBc, and rra|>inttian U csrried on byllio latent! put* of the 1 
The "Tjota." ii leparsted from the "nauplitix" by havins 11 
body, latBc paired eyei (lometimes with a median eye), and a caitpm 
The form proper to the adull is not aitiineil until after mvmsI ntnia, 
conMltalin|r a Eeauine melamorplKiitii, liiough onewhicli li t£K1«d bjrnif 
padual siaf^ 



annclosa: crustacka. 



2»9 



or " foot-jairs," and a bifid lower lip, or " metaitomx" The 
five remaining segments of the thorax cany Ibc five pairs of 
ambulatory legs, of which the first (fig. 74, i) constitute the 
great davn, or " chela; ; " the next two pain (1 and 3} are also 




CMMinilbwlhi cnaleMB «t aip|na(-<l*'n: i. Snoml piit af Itei. iln ihilu<- 
\ t1ilt4 ••'• oXIici. iIh ihtUit ; t ami ^ Liu li<>« luln of UDtuldoi}' !•£•. *><li 
Mi^y pimttii em t«rtki ; ■ ABicnuuLs ; «b Urcu uIhuw i m Cw«rHA 

cbdatc, though much smaller ; and the last two pain are ter- 
niaated by sunply pointed cxtremitic!. The segments of the 
•bdoinca cany each a pair of lutatory limb!i, or " swimmercts," 
the lut pftir being greatly expanded, itnd constituting, with the 



aio 



MANUAL OF ZOOLOGY. 



" tdson," a porerfiil caudal fin. Most posteriori)' of «tl ii tbt 
post^ana) plate, or " tcUon," which may be looked upon dAs 
as ail aiy-gos appendage, or aa a tcrminat si^mcnt whidi hu 
no Lktenl appendages. 

Tlic mouth leads by a short cesophagus into a globoK 
stonuch, in the cardiac portion of which b a calcareous afft- 
ratus for tritumling the food, which is commonly called Ibt 
" Udy in the lobster." The intestine is continued bockvudi 
from the stomach without convolutions, and the anal apcrlure 
is situated just in front of the tclson. 1'hcrc is also a mfr 
developed liver, consiuing of tn-o lobes which open by scptiale 
ducts into the in lest inc. 

The heart is situated dorsally, and consists of a single ffAj- 
gonal contractile sac, which opens by valvular apertures into 
a surroundinK venous sinus, inappropriately called the "peri- 
cardium." 1 he heart is filled with oxygenated blood deriiwl 
ttxtm the gills, and proi^cU the aerated blood through eitry 
part of the body. The gills (fig. 63, 3,;) are pyramidal bodies 
attached to the bases of the legs, and protected by (he Hda cf 
the carapace. They consist each of a central stem supporting 
Diuncrous lamina:, and they are richly supplied with blood, bnl 
are not dliated. The wuter which occupies the giU-Ghanben 
is renovated partly by the movements of the legs, and panly 
by the expanded qiipoditc of the second pair of nuJuilH; 
which c<m:ttantly spoons out the water from the front of the 
brandiial chamber, and thus causes an cntr^' of fresh water by 
the posterior aperture of the cavity. 

The nervous system is of the normal " homogangliatc" xyf*. 
consisting of a lougittidina] scries of gsnglia of different bks, 
united by coiiimimira] cords, and placed along the ventral sa- 
face of the body, llie organs of sense consist ot the two com- 
pound eyes, the two ]>airs of anteniue, and two audttoiy sacs- 

The sexes are invariably distinct, and the generative pro- 
ducts are conveyed to the exterior by eflerent ducts, wudi 
open at the base of one of the pairs of thoracic tegs. The 
ovum is " meroblastic," & ponion only of the vilellus undei- 
going segmentation. The neural side of the body — that is 10 
say, the ventral surface — appears on the sur£icc of the ovum, 
so that the embryo is built up &om below, and the umbilktt 
is situated posteriorly. 

Tribe B. Anomvra. — The Decapods which belong to this 
tribe are distinguiNhed by the condition of the abdomen, which 
is neither so well developed as in the AVaerura, nor so niili- 
mentaiy as in Crubi^ Further, the abdomen does Dot temi- 
nate posteriorly In a caudal &n, as In the L«bat«r. The 



ANKULOSA: CRUSTACEA. 



231 



development in the Atusmura appears inrariablx 10 talce place 
through Zoca-fonns. 

The most lamiliar of the Anomura aie the Hertnit-crabt 
(FapiriJas). In the common Hermit-crab (Pagurus Btrnhar- 
Jut) the atMlomen \s quite »oft, and is merely enclosed in a 
membrane, 10 that the animal is compelled to protect itself by 
adopting the empty shell of some MoUuiic, luch as the common 
Whelk, which it changes at will, when loo snulL The Hermit 
b provided with a icmiinal caudal §uckcr, and with two or 
three pairs of rudiineiitar>- feet developed upon the abdomen, 
by means ol whkh he retains hh position within his borrowed 
dwelling. Tlte abdominal appendages, however, are moilly 
uasynunetrkal. The carapace is not strong, but the claws are 




ng.»-buhrnn. 7«c 8»lBir SrUa-CnbtV*^ ifw'oAA^ 

well developed, one being always larger than the oilier. Other 
fanas of the Ammura arc the Sjiongc-crabs {Dr^mia), the 
Cnb^obslers {Pgndlamt). and the Tree-crabs {Birgus). 

Thibk C. BHACHVtJitA. — 'ITic "short-tailed" Deirapm!*, or 
Crabs, arc distinguished from the two picccding tribes by the 




131 



MANUAL OF ZOOLOGY. 



nidlmeBtarv condition of the iibdomen, which is vtry shun, 
and is tucked up beneath tlie ci:)>lialothorax, the latter beng 
disproportionately large. The extremity of the abdomen it 
not provided with any appeodage, and it is rocrdy emplofd 
by the female to carry the ova. The Crabs (%. 75) arc moclljr 
furnUlicd with ambulatory limbs, and are rarely fomied n 
swimminK. niost of them being Httotal in their habits, and lom 
even living inland. 

In all the essential points of their anatomy the Crabs da Mt 
diflerfrom the LobHer and the othvt A/aerura; but they ate 
decidedly higher in their oi^aniution. Tliis in es|)eciallf fan 
in the dis[io:«iti()n of the nervous system, the v'cntral g^t^ 
in the Cr;ib being ci'>n<:entrated into a single targe gMgbon, 
from which nervous hlamenls arc sent to all t>arts of the bodf- 
In the Land-CT^ (Otfanmuf) respiration is by brsodux. 
but tlieie is ahnost always ait aperture behind tlie canpace to 
the admission of air. They arc distributed over the <nni 
coimtries of the Old and New Worlds, as wrell as AusUslia. 
They are euenttally terrestrial in 
their habits, and migrate in Urge 
bodies to the sea, in order to lay 
their eggs. Besides the (we <r«w- 
eiai, mcEnbers of Other very diSani 
families live more or leu cotutaoilT 
on dr>' land, and have air admiltc^ 
directly into t)ie brancht^it clutnbtr. 
Amongst these are the Calling-<nil» 
[Gelanmus), the Frc^-crabs {Ram- 
Ha), and the Sand<rabs (Otyfada). 

Kqiroduction in the Crabs it the 

same as in the Muerura, but the 

^/^.Z/"^ *^'"' '' ^^^ **"■* '* exceedingly unlike the aduh. 

t^^^^"^ ™*"" and approximates closely to the type 

of the Matrura, another ptoof ttut 

the Braihyura stand higher in the Crustacean scale. The 

larval Crab was oii^naily described as 3 distinct animal, vxAa 

the name of ilvo (fig. 76). presenting in this condition a loOJ 

and well-devel<ii)ed abdomen. It is only after several sureO' 

tive moults that the young Crab assumes its charactciidK 

Brachyurousform.and acitmres by gradual changes the fconnts 

which distinguish the adult. The Zoftt of the Crabs are 1 

distinguished by the pOHcssion of long spines develoj>ed4 

the carapace. When first liberated froin the egg, the f ' 

enveloped in a larval skin or membrane, whicn^is shed 

few hours. 





ANNULOSA : CRUSTACEA. 833 



CHAPTER XXXV. 
DISTRIBUTION OF THE CRUSTACEA. 



DrsntiBtmoN of Ckustacka in Space. — The following gene- 
ral pnDcipkt have l>ccn bid (town by Milne-Edwarai with 
rc]!ant to the geogni>hical distribution of the Crustatta :~~ 

I. The dilTcTcnl fonns and modes of organisation of the 
Crui/Mra sore more varied and numerous in proportion as we 
pass from the polar regions loivards the equator. 

3. The number of different species is not only greater, but 
the Dumber of types is greater in warm regions as compared 
with cold. 

3. The higher Crusttuai are cither entirely wanting or are 
sparingly reprevenied in the colder regions of the globe, but 
increa)« rapidly in relative numbers as the equator is ap- 
proached. 

4. The siie alttinc<l by the Crustatra is greater on the aver- 
age in «-ann regions than in colder climates. 

5. The special points of structure which ue characteristic 
of the dilTerent groups of Cruitatea are more strongly niaiii- 

^^etted in the warmer regions of the globe. 

^B 6. There exists a decided relation between the temperature 

^Bf any given region and the character of its Crustacean fauna ; 

^^^ilar gmeru forms being usually found occupying regions of 

^Oie same cllmatal character. 

I Distribution of Crustacea in Time, — The class Crustacea 
b laigcly rc]>rcsentcd in past time, ranging from the Cambrian 
Rocks up to the present day. The oldest £amtlies of the Crus' 
taeea are the TVihbita and the Eurypierida, both of which are 
cxdnsively Paheozoic, and died out at the close of the Car* 
booifcrous ei>och. It Is worthy of notice how larval are the 
choractcrt or tliese ancient groups when compared with their 
tnodcni successors. Of the remaining orders the Cirriptdia, 
OttraaiAi, and FAyiUfada are the three which ore most largely 

; fepfcseoted. 

I. Cirriffdia. — The Cinipcdcs are hardly Vnown as Pa!a:o- 

' toic fossils, but valves of a singular member of this order ( Tur- 

^K#^/w/) have been found in the Silurian Rocks of Scotland. 

^■Cith this exception, the Cirri|ic<les are entirely conhned in 

^^Ml tin»c to the Secondary and Tcninry epochs. The Bala- 
mida arc the most common, commencing, as &r as Is yet 
known, in the Eoci-ne period, and attaining their maximum In 
Kccat scat. The Vtrnuidm commence in the Clialk, and the 




234 



MASUAI, OF 20OL0GV. 



Lefadi^a bej^n still lower, in the Jurassic Rocks, and itaia 
their muimuin uf (1evelo[Hneni in the Cretaceoia epodt. 

I. Oj/raAh/fi.— Small Ostracode Cruttaeta are exuemtly 
nbundanl m fossils in many fonDaiions, and extend from llie 
Lower Silurian period ii[> to the present day. 

3. Phyllopoda. — Remains of Crustaccins supposed to belong 
to this order are found in the Palicozoic Rocks. I/ymfwarii 
is foimd in the Upper Cambrian, Caryecaris in the Lowa 
Silurian, Cfmliaairis in the Upper Siluiiui, and Dilhyrctant 
in the CarboniferouA Limestone. All these fonns, wttli other 
similar ones, are belie\'ed to be most cloiely allied to the recem 
Apui and Ndialia. 

4. Trileiiila. — The Trilobites are exclusively Palaeozoic fet- 
sils. In the Upper Cambrian Rocks — the so^allcd " primor- 
dial lonc" — there occurs a singular group of Trilobites — the 
so-called primordial Trilobites— distinguished by the possts- 
sion of many lar\'al characters. In the Lower and Upper 
Silurian Rucks tlic Trilobites attain their maximura of deiYl- 
opmenu They are still well represented in the Devonian 
Rocks ; but they die out completely before the close of the I 
Carboniferous epoch, being represented in the Mountain Lime- ' 
stone by three gcners only {PkUliptia, Brachymtiopiu, and 

5. Euryjittrida. — These, like the last, arc cniirely PaleozoKi, 
attaining their maximum in the Upper Silurian and Devoniaa 
fbrmalions, and dying out in iKe Carboniferous Rocka. Ptaj- 
g)tfut, Earypienii, and SlimoHiaixc the xroia characteriMic genera 

6. Xiphosura. — The genua /.iuiulus commenced, as far a£ is 
yet known, in the i'ermian period, and baa survived up to the 
jirescnt day. Its f rst appearance, therefore, was ^ust at the 
close of the Palwo^oic epoch. The two retnainmg gcncn, 
which constitute with Zimu/us this sub-ordci (viz., Bdiutm^ 
and PrestK'uhia). arc I'olwozoic, and arc not known to occar j 
out of the Carboniferous Rocks. 

7. /upoda, — The earliest known Isopod is the JWa^fimtait 
of tlic Permian Rocka 

8. Slomupoifn. — This order is doubtfully represented in the 
Carboniferous Rocks. 

9. Paapoda. — The Decapods, with the i-xce]>tion of a single 
doubtful lorm from the Carboniferous Rocks, are not known is 
have existed at all during the I'alaroioic period ; but they ixe 
well represented, in all their three tribes, in the Secondary and 
Tertiary epochs, attaining their raaximuro at the present day. 
The London Clay (Eocene) is especially rich in the remaist 
of Moirnra and £r^<kyura. 







ANNULOSA : ARACHNIDA. 235 



CHAPTER XXXVI. 
ARACHNIDA. 



Class If. Arachnida. — ^The Aracfimda—'mc\\iA\ng the Spi- 
ders, Scoqiions, Mites, &c — posse«t alraotl x\\ the e»<nittal 
chantctcra of th« Crusfacea, to which they arc very closely 
allied, llius, the body is divided into n variable number of 
somites, some of which aic always provided with articulated 
a{>pend«gc&. A pair of g-inglia is primitively developed in 
each soinitc, and the neural &y&tan is placed ventrally. The 
heart, when present, i» ^ways situated on tlie opposite side of 
the ftlimeoiary auial to the chain of ganglia. I'he rcsplruli>ry 
oigans, hiwever, whenever these are dirfetcnliated, arc never 
ID th« fonn of bnutchtie as in the Cnntaaa, but are in the fonn 
cither of putnionftry vesides or sacs, or of ramified tubeSi 
formed by an involution of the integument, and fitted for 
breathing air directly. Further, there are never " more than 
lour pairs of locomotive limbs, and the somites of the abdontcn, 
even when ihex are well develoiicil, ate never provided with 
limbs;" the reverse being the case amongst the Cnulaem. 
Lastly, " in the higher AraeAniiin, as in the higher Crvitaeta, 
the body is composed of twenty somites, six of which arc al- 
lotted to the head ; but. in the forrnex class, one of the two 
normal pairs of antennae is never developed, and the eyes are 
slwjys sessile; while, in the higher Crustaeea, the e>'e5 are 
moonted upon movable peduncles, and both pairs of antennae 
are developed."— (Husle v.) 

The head in the Arachnida is always amalgamate<l with the 
thorax, to form a "cephalothorax;" the integument is usually 
chitinous, and the locomotive limbs arc mostly simitar in form 
to tboae of insects, and arc usually terminated by two hooks. 

In many of the AfVihnida the integument remains soft over 
the entire body ; in others, as in the majority of Spiders, the 
abdomen remains soft and flexible, whilst the cephalothorax is 
more or lets hard and diiiinous ; in the Scorpions, again, the 
iotraumcnt over tlie whole body forms a strong diitinous slieU. 

Tlie typical somite of the Arathnida is constituted upon 
exactly the samtf plan as that of the Crustacea, consisfting 
essentially of a dorsal and ventral arc ; the fonncr composeo 
of a cenual piece, or "tergiim," and of two lateral pieces, or 
"cpimera;" whilst the latter is made up of a median " slcr* 
num" and of two lateral "cpi&lerna." 

As regards the composition of tlie ccpbaloihorax of Spiders, 




2^6 



MANUAL OF ZOOLOGY. 



" ihc tergal elements of ihc coalesced segments arc wanting, 
and tlie back o( tlie ihorax is prolccied by the elongation, con- 
veisencc, and central coDfluencc of ilie epiineral pieces; (be 
sternal elements have coalesced into the broad pbte in the 
centre of the origins o( the ambulator}' legx, fiom which it it 

separated by the cpistcmal elementi The non-devel- 

opiuent of the lei^l elements expluns the absence of wingt.' 
— <Owcn.) 

The mouth is situated, in all the Aroihnida, in the anterior 
segment of the body, and is surrounded by sucioriil or tnisti' 
calory appendages. In the higher ArufhnUa, the mouth ii 
provided from before liaclcwards witli the following ap]>endages 
(%' 77< 4)- ■' ^ P^r of^ "mandibles," used for prehentioo. 
3. A pair of "maxillw," each of which is provided with a long 
jointed appendage, the " maxtlUry palp." 3. A lower lip, or 
" labium." In the Scorpion, an upper lip, or " labrura," b 
also present. 

In the Spiders (fig. 77, 4) each mandible tciminates in a sharp 
movable hook, which possesses an aperture at its extremity 
cx>mmitnicating by a canal with a gland, which is placed in the 

S receding joint of the mandible, and secretes a poisonous 
uid. The maxillary palps in the Spiders are long, jointed 
appendages, terminated in the females by pointed claws, but 
frequently swollen, and carrying a special sexual apparatus in 
the males. 

In the Scorpions (fig. ;;, i) the mandibles arc slwrt, aad 
terminate in strong pincers, or " chelicerte." The maullaiy 
palpi are also greatly devclopetl, and constitute iiowerfid 
eraspingdan'x, or "chel»^" In the genus Gaitadet, tne moo- 
dibles, like those of the Scorpion, constitute "chdioerK," 
though comparatively much larger and longer ; but the maxil- 
lai)- palps arc not developed into "cheltc" 

AVith regard to antenna:, these organs, as swh, do not exist 
in the AnuAnida. It is generally believed, however, that the 
mandiMts of the ArM/inula arc tniiy homologues, not of the 
parts which bear the same name in the other Arthrvfcda, \M 
of the antenna. Tlic antennae, therefore, of the Sj)iderx, are 
converted into prehensile and oD'ensive weapons ; whilst in the 
Scorpions, as in the Ring-ciabs, they are develoiied into nip- 
ping-claws, or chel«. • 

In the lower Arachmda, the organs of the mouth, thou^ 
essentially the same as in the higher forms, ore enveloped in a 
sheath, formed by the labium and maxilla^ whibt the man- 
dibles are often joined together so as to constitute a species of 
lancet. 



« 



\ 




ANNI'LOSA: ARACIINIDA. 



237 



The mouth open* into a pharynx, which is of remtricaUy 
I calibre in the true apidera, all o( which live timpl]i' on 
ic juices of their t>Tey. The intcttinAl canal is uinully short 





[ 77. — UerrholngT of AndiDiiU. t. OrBMii of ibc Bouih in the Scaijuob. on 
_M *^ - "f HandiMH (inttnnji) caavtnid Into dula, and aU*A tht chvJiccnc i 
> MMlUiajF pklpl ffully donliinl. khI fonaiu umis chtla. >. Ttlnn oT ih« 
Senpiea. ), Oh tt ihi iMsmuul HtBocaH tfttm T 



, , ^ df c)i« [HjiRionanr ucL «. T^HvarH d^wt/vv, Ihc TOAimoB 

SfUo buki (tcml hniB bilaw : iSptnmww; ■OJaadlblMwiih ilwli uifonul 
h«ln 111 III ir (be audililn m ih« waiU*. and bdven tlM Imxi til Lime u Ur 
bUiNt i / IW iBuDlux palpi *ilh Ibcir nlaiiei] luBid nircmiliau 



: St«|iiaB, •hMUic ill* " uig- 



and ttnight, 00 convolutions intervening between (he mouth 
aad the apeiture of the anus. Often, however, lateral cxca 
an; appended to the alimenlaiy tube. Salivar}- gbn<b are also 
present, ax vretl as ramiiied tubeit, tupnosecl to pcrfomi (h« 
fiiDctiofUi of a kidney, and to corrcsiiona to tite " Malpightan 
vessels " of InKcctx. 

The circulation in the AratAai/Ai a maintained by a dorsal 
heart, which U sittialcd above the alimentary canal. Usually 
he heart is greatly elongated, and resembles the "dorsal 
' of the/«i«Aj. In the lower v^nwA«jVA». howcvirr, there 
■ central organ of the circitUtion. and there are no dilTer- 
ntiated blood-vesKls. All the Ara^AniJa hreaihe the air 
ectly, and the respiratory function i» jierformed by the 
leral xurface of the bo«ly {as in the lowest membent of the 
^ass), or by ramiiied air-tubes, teTm«l " trachea^" or by dis- 
tinct pulmonary chamben or sacs ; or, lastly, by a combination 
of tiadiec and polmonaty vehicles. llic"irachL-.'G" consist of 
^■unified or (aaacahted tubes, opening upon the surface of the 




238 



MANUAL OF ZOOLOCV. 



tmm 



body by distinct apertures, called "stigmau." The wiBt 
of th« tube are generally prevenled from collapsing by nwus 
of a chilinoiis fibre or ftUment, which is coiled up into a spinl, 
and is situated beneath tlteir epithelial lining. The ptilnonaty 
sacs nre simple involutions of the integument, abutiOantly iup- 
pbed with blood ; the vaKcuIor surface thus formed being in- 
creased in Riea by the development of n number of close^ec 
membranous lamclisc, or vascular plates, which project into 
the interior of the cavitj-. like the trnchcar, the pulmonoiy 
sacs conununicatc with the exicrioi by minute apertures, or 
" stigmau ■■ (fig. ;;, 3). 

The nervous ay«cni is of tlie nonnal articulate tyj)e, liut a 
often much concentrated. In the Spiders there is a cqihalic 
or " cerebral " ganglion, a large tlioracic ganglion, and in some 
instances a small ab<I<)miual ganglion. In »ome of the lowci 
foms the arrinilatc type of nervous system i.^ lost, aiwl tbcrc ii 
metdy a ganglionic mass which is traversed by (he gulleL In 
none of tlic AraeAnida are compound eyes present,and in none 
are the eyes supported upon foot-stalks. l~hc organs of visiOQ, 
when ]>reseni, arc in the form of from two 10 eight simple e)'Oi 
or "ocelli." 

In all the Ara<hnUa, with t!ie exception of the Tardtgraii. 
the sexes are distinct. The great majority of ihc AratkniJa 
are oviparous, and in most cases the iarvn arc like tlie aduti in 
all except in siic. In some cases, however (Acariiia), the 
1ar%'» have only six legs, and do not attain the proper four 
pairs of legs imtil al^cr some moults. 

The Arathaida may be divided into two great sectioni or 
SUb-clajses — vi)^, the Tratkfaria, in which mpiration is effected 
by the general surface of the body, or by Irachcte, and there 
are ne%-cr more than four ocelli ; and the Pulmonaria, in whicb 
respiration is effected by pulmonary sacs, cither alone or 
bined with trachex, and there arc six or more eyes. 



« 



( 



CHAPTER XXXVII. 

DIVISIONS OF THE ARACHNIDA. 

TliTiRios A. Tracheabia. — Kafiimtimaitantvusttrbjlr 
Eyts nafr m<^e than/imr in number. 

The '/'m^A/iiria comprise three orders-^viz., the PtfdatMUlil, 
the Afttrimi or Mm«mtrvs9maiay and the AddariAnttmata. 




ANNUU>5A: ARiXCHNIDA. 



239 



IKDER I. PoDOSOMATA [FtHfofioih). — The members of this 
order, sumtriimci called " Sea-spiders,* have been placed alicr- 
natcly lunoitgX the Araehnida and the Crvitecta, tlieir uue 
position being rendered doubtful by the fact thai, though 
roarinc id their hnbiis, they |)o»^c» no ililTeienii.iicd rrsj)in>- 
toty organs. I'hcy possess, however, no more than four pait^ 
od" legs, and would therefore appear to be properly referable 
to the Araehiiia. The commoner forms of the P^eiotnala 
(such as Nympken and Py<nag<>num) may be found on the sea- 
coast at low water, crawlinf; about amongut marine plants or 
hiding beneath stones. Some si>ede!t of tlie latter genus arc 
asserted to be parasitic upon fishes and other marine animals, 
but the commop British species {P. iitt^ra/e) is free when 
adult, and does not apjieai to be parasitic »t any sUige of its 
existence (fig. 78, a). The legs consist of four pairs, some- 
times gready exceeding the body in length, and sometimes 
cofltainin^c caecal prolongations of tlie digcsiitc cavity for a 
portion of th«ir length. The mouth is provided wiili a pair of 
"chelicer^" or chelate mandibles, and with t«-o well-developed 
maxUlary jalpi, )>ehind which iti the female arc a pair of false 
Iks which carry the ova. The abdomen is rudimentary. 
'Imu^ there arc no respiratory organs, there is a distinct 
heart The sexes are in different individuals. 

Ordf.r 11. AcAKiSA or MoNoiiERosoMATA. — The members 
of (hi* order postua an unsegmented abdomen which is fused 
with the ceplulothonx into a single moxs. Respiration is 
effected by tracheic Most of tlie Aearina are parasitic, and 
the most familbr arc the Mites and Tick^ 

fiimi/y 1. JJngvatuJina or Pcniailomitia. — The members of 
this family arc singular vermiform animals, found as parasites 
Id the frontal sinuses and lungs of some Vencbrates. In their 
adult condition they poucis no external organs except two 
pairs of hooks, representing limbs, placed near the mouth. 
I'hey thus closely ap|troxiroate to the Taniada, beside which 
they have been geneially placed. In the young condition, 
however, they possess four arlicubted legs, and even in the 
adult state the characters of tlic nervous s)-stcm nrc higher 
than those of the Sc^ieatia. There are no differentiated organs 
of respiration, and there are no circulatory organs, but the 
sexes arc distinct 

Pamify 2. .Vatraii^tidir (Tardisrada or Arftiua). — The 
'• Sloth ■• or *' Bear animalcules," which compose this family, 
are mtcmscopic anieoals, vei^- much like fioii/ers, found in 
damfi movt and in the gutters of houses. The ncr\'ous system 
consists oi four ganglia, and there is a suctorial mouth, with 




240 



MANUAL OF ZOOLOGV. 



nidimeDtary jaws or stilcts. The Kbdomcn is und< 
and there are four pairs of rudimcnury Iegs> The/ ck^ 
no traces of either Giiculaioty or respiratory organs, and Ibe 
sexes aie united in the same individual. 

Famiiy 3. A<arida.~-^\n% family includes the Mite*. Tick* 
and Water- miles, some of which ore jiaraxitic, whilst otbcn 
arc frec> and some are evvn aquatic in their habits. The moatli 
is formed for suction. There is no definite line of dcmarcatioo 
between the unscgmcntcd abdomen and the cephaJotbonui. 

In the true Atari (fig. 78, b\ of which the Cheese-mile nay 
be taken as an example, there are four pairs of legs, adapted' 
for walking, and the mouth is provided with distinct roandiMci. 
Be«i(lo the Checse-mite {A. dometlieui), another well known 
species is the Aeami dcitrucfar, which feeds upon various lOO- 
logical specimens, an<l is very annoyin); to the naturalist Id 
the SunopUt seabui — tlie cause of the skin-cliscasc known ai 
the " itch " — the two anterior paire of legs nrc pro^-idcd with 
suckcTv, and the two posterior are terminated by bristles ; the 
mouth, also, is furnished with bristles. In the Ticks (/jK^j 
the mouth is provided with a beak, or "rostrum," whi 
allies tliem to pierce the skin, and retain their hold firmly, 
the Jiydrathmda (fig. 78, 0. or Waier-iuites, the head it fif' 



I 




"SocaUe" inilc*i c /f/rfracl*) jibMlu, oh sf Ihi "Wtiftttilt^' 

nishcd with two or four ocelli, and there ore four pairs of haiiy 
natatory legs. They arc parasitic, during at least a portjon of 
their existence, upon Water-beetles and other aquatic intccts- 
They pass through a meUmorphosis, the larva bein^ hcxspod. 
or having only three pain of legs. I'he Garden-inites (?>»■- 
biJidtt) and Spider-mitca {GaHMtda) live t^>on ]>lantt; the 
Wood-mites (Ort&T//^i?) and Harvest-ticks (/^V>/<x) arc to bt 
found ttmongst moss and heiba^ orcreeptnz upon ircettf 
nones; whilst the ttue Ticks {I:^uia) attach uemselves pan- 




annulosa: akachnida. 



341 



iy hy mtaoB of their suctorial moutli to the bodies of 
Mammaib, such as &Uee:ii, oxen, dogs, &c. SevenX 
■ {ThalfuturMAna, PonlitmdiHa, &c.) have been Touiid to 
salt water, and several species of Trombidida live habit- 
ually between tide-inarkf. 

Another member of the Aatrma is the curious little Dtmedtx 
JtlHathntm. which is found in the sebaceous follicles of 'man, 
especially in the neighbourhood of the nose. It is probable 
that very few, if any, individuals arc exempt from this harm- 
less )>ara&itc. 

Oroek III, Adelarthrosomata. — The members of tliis 
order, coroprisint; the HarvMt-s]iidcrs, the Book scorpions, &c., 
are distinguished from the prcccdiiig by the pos3e:Mion of an 
abdomen, which is more or Ic&s distinctly *cgmcnied, but 
nerally exhibiu no line of separation from Ihc ccphnloihorax, 
: two regions being of cqn.il breadth and conjoined together, 
mouth is furnished willi masticatory appendages, and 
^ration is effected by trachea;, which open on the lower 
nee of die body by two or four stigmata. 
Family t. Phalangiiia. — Tlie well known "Harvest-spiders" 
'belong to ilii» family. They .lie chaxacteHscd by the great 
length of the Ic^ and by the filiform maxillary palpi, tcmii- 
Rated by simple hooks. 

family 2. PstuJesmrpioniJa (CAelifirida). — The "Book- 
scorpion " {CMi/er) is a common little animal in old books. 
It is distinguished by the fact that the maxillary palpi arc of 
^br^c size, and arc converted into nipping-claws or chela;, thus 
jtving the animal the appearance of a Scor|>ion in miniature. 
/vmi/y 3. Sa/pitgidx.— \n this family the abdomen is not 
nly very distinctly segmented, but is also clearly sepaTate4 
the abdomen. The mandibles in Galmla. which is the 
of the group, are chelate, but the maxillary [lalpi consti- 
tute long feet. 

Division B, Pulmonaria. — Respiration by fuiitonary sad 
alafK, or fy puluumary tafs (mjoittd with trathta. Eyfs six 
tr m^re in numbfr. Abd&men usuaUy distintt from the (efhalo- 
Ihcrax. 

This dtvisioR comprises the higher Arathmda, such as the 
Scorpions, and the majority of what are commonly known as 
Spiders ; the former consimiting the order of the J'^ipal/i, 
the IsitVT that of the Araneida or Dimtros^mata. 

OrOKK I. pEUifAiPl.^In [his order arc the true Scorpions. 
together with certain odier animals which arc in some respects 
intermediate between the Scorpions and the true Spiders. 
ITie mei nbcia of ibJa order arc dJstinguUlicd by the tact that 



242 



UANUAL OP ZOOLOGY. 



rhe :th<lomen in all is distinctly ^eemcnted, but is not : 
from ilic cephiilothonx by a welltiiaiked constriction. Tbcjr 
agree in this character with ^KAJelarthrosffmala; hence tfe 
two are Komctimes united into a single order {Artkiv^ttrtt), 
but tlicy nrc scjiaralcd by the nature gS the rcsi>iralofy orguh 
the latter brc;ttJiing by trachcic, and not by pulmonary sacs. 

J-'amily i. Seorpicnida. — ^Thc Scorpions arc amongst the bat 
knovm of the Arachmda, as well as being amongst the Utg«. 
They are distinguished by their long, distinctly segmented ab- 
domen, terminattDg iii a hooked daw (figs. 77, 79). Tbb cla«, 
which is really a modified "tclson," is the chief offensive »-c^>aa 
of the Scorpion, and is perforated at its point by the duct cf 1 
poison-gland which is situated at its base. The abdomen li 
composed of twelve somites, but there ix no evident line of d^ 
marcation between this r^on and the cqihaloihorax. 'IV 
thoRtcic segments carry four pairs of ambuk^tor)- feet. Then 
are six, eight, or melvc simple eyes. The maxillary polpt are 




r<g. )9.— SOMplon (raluiAl> 



greatly developed, and constitute strong nipping •clam, or 
"chelae" (figs. 77, 79). The mandibles (antenna) abo fom 
claws, or " chelicera." The respiratory organs are in dkc 
form of pulmonary sacs, four on eadi side, opening upon the 
under surface of the abdomen by as many stigmata, each tf 
whidi is surrounded by a raised margin, or "peritrema'ffifr 

77. 3)- 

Tlie Scorpions are mostly inhabitanis of warm rocions. »« 
their sting, though much exaggerated, Is of a very lem 
nature. 'ITicy live under stones or in dark devices, and ra> 
swiftly, carrying the tail cur\-cd over the back. They fetdfl* 
Insects, which they hold in the chelate palpi and stjog » 
death. 

Family 2. Thdypkenida, — The members of this fikonlf i> 




emat appoinuice closely resemble the tnie Spidcre, from 
ich they are lepanttcd hy the possession of a segmented 
lomen, and long splnose patpt, and by the absence of spin- 
"cta. They are distinguished from the Storpionidx by the 
lalgunation of the hctd and thorax into a single ma&s, which 
etesrly separated from the abdomen by a slight constriction, 
well as by the i&xX that the maxillary palpi terminate in 
nrsble claws instead of chebe. Further, the extremity of 
; abdomen is not furnished with a lenuinat hook, or "sting." 
ORDtR II. AHASKiDA Or Spii.cROCASTitA. — This Order in- 
idcs the tnic Spidcix, which -ire chamcterised by the amal- 
tnalion of the cephalic and thoracic sc-gments into a single 
us, and by the generally soft, unscgmentcd abdomen, attached 
the cephaktborax by a constricted portion, or peduncle. 
.epilation b effected by pulmonary sacs usually in combina- 
D with tracheae (Hence the name Pulmi>lraehearM, some- 
m apphed to the order.) The number of the pulmonary 
cs is sinalleT in the true Spi<Ien than in the Scorpions, being 
her two or four, opening by aa many stigmata upon the 
der utrfacc of the abdomen. 

liie head txars from six to eight simple eyes ; the man- 
ales are simply hooked, and arc perforated by the duct of 
^aod which secretes > poisonous fiutd ; and the maxillary 
Ipi are never chelate. 

Spiders (fig- So) arc all predoceous animaU, and many of 
i the povrcr of constructing webs for the capture 




Fic •a.-Anx-U. T^rUin •^W.R{r<fukV 



f their prey or for lining their abodes. For the production 
t the web, Sjuden are furnished u-ith special glanns, situated 
t the extremity of the al)doroen. The secretion of these 
hods is a viscid fluid, which hardens rapidly on exposure to 
ukd wbidi is cast into its proper, thread-like shape, by 



I 



A 



344 



MANUAL OF ZOOLOGY. 



being passed through what are called the " spinnerets." Thoc ] 
an little conical or cylindrical organs, four or six in numbei,! 
situated bc)ow the extreniii^- of the abdomen. The txatmr 1 
ducu of the glands opcii into the spinnerets, each of *Ua I 
has its apex perforated by a gical number of mimiie l«be^J 
through which the sccietion of the glands has to pus ~ 
reaching the air. Many spiders, however, do not coi 
any web, unless it be for their own habitations, but huM 1 
prey for themselves. 

As regards the reproductive process in the Spiders, it ap, 
certain Uiat the act of copulation, so to speak, is performed I . . 
the males by means of the maxillary palpi, the cxucmitics of 
which arc specially modiAcd for ilii* purpose. The teste wt 
abdominal, but the semen appears to Ix: stored up in the 
enlarged extremities of the maxillarj- [<nl|>s, which thus prt- 
form the part of the vesicular seminalcs. " The most canM 
observations, repeated by the most attentive and experienoij 
entomologist, have led to the conviction that the ora . 
fertilised by tlie alternate introduction into the vulva of i 
appen<lage.v of the two jialpi of llie male. Treviranus's nip 
position that these acts are merely preliminary stimuli, 
receive<l no confirmation, and is rcjectctl by I)u^«, WestwoodL 
and Blackwall ; and with good reason, as llic detection of the 
spermatozoa in the palpal vesicles has shown. . . . Dofb 
offers the very probable suggestion thai the mate himself may 
apply the dilated cavities of the palpi to the abdominal aper- 
ture (of the testes), and receive from the vasa defcrentia the 
fertilising Duid, preparatory to the union. . . . Certain ii 
is that an explanation of ihi.t singular condition of the male 
apparatus, in which the intromiiicnl organ is transfevred to the 
remote and outstnctchcd palp, is afforded by th« insatiable 
pronencss to slay and devour in the females of these uai 
predaceous of articulated animals," — (Owen.) 

The Spiders arc oviparous, and the young pass throng M, 
netomorphosis ; but they cast their skins, or moult, repeatedly,! 
before they attain the sijic of the adult. " 

Distribution of .Arachsida in Time. — ^The .rffw*«i* 
arc only very rarely found in a fossil condition. As far u i> i 
yet known, both the Scorpions and the tr\ie Spiders appear w | 
have their commencement in the Carboniferous epoch, the 
former being rej^rcsentcd by the celebrated C^^Alh!*f 
senier from the Coal-measures of Hohcmia. Sptders ue «1» J 
known to occur in the Jurassic Rocks {Sulenhofen Slales) u' [ 
in the Tcniaiy period. 




CHAPTER XXXVIIt. 

MVRIAPODA. 



MrxiAroDA. — The Myriafmh arc <lc^ncd as ar- 
MO/i in wkui Ih4 he^ni is distind, and the remainder 

is divided inti} nrarly similar segnunti, the Ihorax 
» dear tine of demar (alien /rem iht abdomm. There 
f oMtauue, and the numbtr cf tKe legs it ahoayt more 
tiri. Rapiratien it by traehtg. 
Iu3 — compfiung the Ccitlipedeii (%. 8i) and the 
Mhc iniegunient is chitinous, th« body is divided 
wr of Bomtto provided with nrticiilaicd appendages, 
rvous uk) circulatory organs arc 

Upon 3 plan simiUr to what we 
n Crustaeta and Ara^hnida. The 
■aiiably <listinct, and there is no 

of d«i»aKaiioii between ihc seg- 
; thorax and those of the abdomen. 
:xcept in Paurapus, always coiMists 
D twenty wmites, and those which 
to the abdomen in the Arathnida 
m ilmiys provided with locomo- 

"The head consists of at least 
plwbty of six, coalescent and modi- 
■ ; and nome of the juiterior seg- 
H botly are, in many genen, coal- 

luTe their af>i>en(uge3 specially 
wbficrve prehension. — (lltixicy.) 
u only nine paire of leg« ; but with 
pa, eleven pairs of legs is the small- 
|kD0<ini in the order. 
liratcwy organs, with one exception, 
Ihose of the insetia and of many of 
tfa in Iwing " trachea;" — that is to 
khich open upon the surface of the 
^le aperture*, or " xtiftmaia," and 
rhich arc strengthened hy a spirally- 

lit of chitinc. The ttnchea; may 

uustomosc with one another as 

iMCCtS. 

^tcs, with the exception of the head and the last 
laqgment, are usually undistinguishable from one 
leach bean a tingle pair of limbs. In some cases, 






246 



MANUAL OP ZOOLOGY. 



however, each tcgtaeai appears to be provided with two pdn 
or appcDda^ics ffig. 82). This is really due to ihe coalocan t 
of the somiics in [»tn>, each apparent itcgmcnt being in reailT 
composed of tB'o amalgamated somites. This is showo. «* 
only by the bigeminal hmbs, but also by the an^ngcmetu of 
the stigmata, which in the normal forms occur on every sko- 
nate Hdk only, whereas in these abenant forms they are Ibuiil 
u]JOii every ring. 

The head always bears a p^ of jointed antennx, rcsemUbg 
those of many Insects, and behind the antennx there isgc» 
rally a variable number of stmpU sessile eyes. In one s|>cda 
(Sai/igeni) comiwund facetted eyes are present ; and in /'.tvt- 
pus the antenna; arc bifid, and can>- many-jointed sppcnd«$(t. 
thus differing wholly from the antcnntc of Insects, and pre- 
senting a decided approximation to the Crtulaaa. 

The young in some cases, on escaping from tlie ecg, posKS 
neatly all the characters of the parents, except that the numbct 
of somites, and consequently of limbs, is alnavs less, and in- 
creases at every change of skin {" moult " or " ecdysis "). la 
most cases, there it a $|)edu of metamor]>hosis, the enAijv 
being at first either devoid of locomotive appendages, « po*- 
scssed of no more ihan three pairs of legs thus reiienibling the 
true hexapod Insects. It is believed, bowcver, that the k^ nf 
these hex^od laivx do not conespond homoIogicaUy with th« 
three pairs of legs proper to adult Insects. In these cases i>ie 
number of 1^ i>roper to the ailult is not obtained until after 
several moults, the entire process being stated to occupy in 
some species a-s much as two years, before maturity is reached 

The Myriafoda are dividetl into three orders — \\t., the 0»- 
l6p«da, the Chilognaiha, and the Patiropoda. 

Order I. Chilopoda. — This order comprise* the we3J- 
known carnivorous Centipedes and their allies, and ik chanvc- 
lerised by the number of legs being rarely indefinitely grat 
(usually from 13 to 20 pairs), by the composition of tlic an- 
tennte out of not less tlian 14 joints (14 to 40 tn* more), aeil 
by the structure of ilie maiticating organs. These consist of 
a i>uir of m.-indibles with small ]Mlpi. a Ubitim, and two p«in 
of "maxilJipcdes," or foot-jaws, of which the second is hooked 
and is perforated for the discharge of a poisonous dutd. Thse 
is not more than one pair of legs to each somite-, and the lat! 
two limbs aTc often directed backwards in the axis of the bo(|f> 
so OS to form a kind of tail. 1'he body in all the Chi^^ e 
lUttencd, aivd tlic generative organs open at the |>ostcrior nJ 
of the body. 

Stpfi^aufra (fig. 81), Liik^ut, and Gt»fiUus are comiion 



i 



Europeti) ge 



ANIfULOSA : MYRIAFODA. 



347 




genera of this order. The onlinai)- Centipedes of 
this oouniT)- .vc pakrtly harmlcts, but those of tropical re- 
gions tometimn attain a length of a foot, or more, and these 
are capable of intliciing very sc%'c[c, and even daogcrous, bites. 
Ori>kk II. Ckilogkaiha. — This order comprises the vege- 
table-eating Millipedes {IttiiJa) and ihc Gallyit-onns (/Wj'da- 
mta). The order is chaJaeterised by the great number of legs, 
^^tadi segment, except the six or seven anterior ones^ bearing 
two pairs ; by the coini>otition of the antennae out of six or 
seven Joints ; and by the stiticturc of the masticating oigsnSf 
which consist of a piair of mandibles without palps, co<rered by 
a lonr lip, composed of the confluent maxilla:. The genera- 
tive apertures arc placed in the anterior portion of the body. 

"psppfiiniljiji^iigiiiili 

Rf. tL-MilUpwia (/••i'hJ. 

In the connnoo Millipede (lulv) the body is composed of 
ftom forty to fifty segments, eadi of which bears two |>airs of 
o^ute, ilirea<l-like Ic^ The /uli of tliis country are of small 
■lie. but an American species attains a length of more thnn 
half a foot. 

OaDEK III. Packopoda. — In this order is only an extra- 
ordinary little Afyriapoti, described by Sir John Liibbock 
oodcr the name of Paur^us. The body is only onc-twcntieili 
itf an indi in length, and consists of ten somites, fumi^ed with 
scattered setft. There arc only nine pairs of Ic^^s, of which 
one i>air is i:arTied by the 3d segment, whilst die 4th, 5th, 6th, 
and 7th Mgmeois carry each two pairs of 1^, and may ihere- 
fore be rcgardcfl ai really <lc}ulile. llie liead is i:omposc<l of 
two tcgments, .ind is not ^rovidc^l with jaw-feet. The antenna: 
are fivc-joinicri, bilid, with three long multi-aiticulaie appcn- 
dagCL The body is white and colourless, and there arc no 
tmcbca, so that respiration must be effected entirely by the 
■kin. Pamvftu is found amongst decaying leaves in damp 
sitnatioDS, and species have been described both front Britain 
■Md America. It Is separated from the Ckilopcda by its small 
^KUier of tegs, the ab»ence of fool-jaws, and the compoiiiiun 
^^tf»e antcnnc out of no more llum five juinis. 
BPiCTHiiitmos OF MvKiAi-<>i>A IN TiME. — Khovo. twenty 
■pedes of MyriafiMia arc known a^ fossils, the oldest ecunplc 
,a ibB order Itaving been found in the Carboniferous epoch. 




248 



MANUAL OF ZOOLOGY. 



From rocks or this Age several species of Chilognathous Myrii- 
potli have been discoverctl. They belong to the geata 
Xytobivi and Arthiulus, and have been placed in a spcciii 
family under the name uf Artkiulida. llic occurrence d 
air-brntthing art iculaie animals (both Arathmda and Mjno- 
poda) in the Carboniferous nenocl i.s noticeable, lh bdog COfr 
tcmporaneous wilh the culicsl knovm tcrrcftrial MoUiUci. 



CHAPTER XXXIX. 

JNSECTA. 

CKJIERAL CHARACTKKS OF THE IS'SCCTA. 

Class IV. Insbcta. — ^The Instela aic defined 8S artialeli 
animah in wAUi the Aaijf, Morax, and aMemtn are iSMtH^ 
thert art three fairs ^ Ifgs hmt m the MontJr; the aUmi» 
it dettUuit of /lyr; a sin^e fair ef oMttniM it jtramt; MMf/r, 
lliere are two pairs ef wings on tAe tk«rax. RtsfiratiM o 
tffeded by troihea. 

In the InsKla the body is divided into a variable nuiabn o( 
definite segments, or somices. some of which are funiisM 
with jointed appendages, and the nervous and circablcfF 
s>-ttem» are constructed upon essentially the same plan u a 
tne Crustatea, Araehnida, and Myriaf/eda. 1^ head, ihocu. 
and abdomen are distinct (fig. S3I, and tlie total number 4 
somites in the body never cjiceeas twcnt>'. " Of lhc»e, fiw 
certainly, and six probably, consiilutc the head, which pes- 
sesscs a pair of antenna:, a pair of mflndiblcs, and two puis of 
maxilisc, the hinder pair of which are coalesceni, and fora tbt 
'Ubium.' Three, or perhaps, in some ca^es, more, soniia 
unite and become specially modified to form the thonx, lo 
which the three pairs of locomoiive liml)S, characteriuic of 
perfect Insects, arc attached. Two additional ]iaiTs of bxo- 
motive organs, the wines, are developed, in most inuctt, 
from the tergal wall* of the second and third thoracic socuus. 
No looomotivi; limbK are ever developed from the abdoiMatif 
the adult inject, but the ventral portions of the abdomMl 
somites, from the eighth backwards, arc oOen metaRMrphowd 
into apiuratuBcs ancillary to the generative function,*— 
(Huxley.) 

The iDiegunent of the Insai«j id the nuture condition, it 





ANNULOSA: IXSECTA. 

: or less hardened by the dqwndon of chilinc, and usually 
ifenns a misting cxoskclcton, to which the muscles arc attached. 
The seyinents of th« head arc amalgamated into « single piece, 
which bears a pair of jointed feelers or aniennte, « pair of eyes, 
tmuUy compound, and the appendages of the mouth. The 
t^ments of the lUorux are also unalganuted into a single 
piece ; Imt this, nwerthelcss, admits of separation into it* con- 
stituent three M>mit« (fig. 83). These we termed respect- 
ively, from before bitckwirds, the " prolhorax," " mesothorax," 
attd " metatborax," and each bears a pair of jointed legs. In 
the great majority of Insects, the dorsal arches of the mcsotho- 
lax and metatiwrax give 
origin each to a pair of 
wing*. 

Kach legconsistsoffrom 
sis to nine joints. The 
&rst of these, which is at- 
tached to the sicmal sur- 
bxx of the thorax, is called 
the "cxMa," and is suc- 
ceeded by a »hort joiiii. 
termed the "trochaniet.' 
lite trochanter is followed 
by a joint, oflen of large 
riie. called the "feimir." 
anil this has anicubied 
to it the " tarsus," which 
may be comi>osed of from 
two to five joints. 

The winp of Iiwecu 
arc menbtanous "flatten- 
ed Tesidcs, sustained by 
slender biit firm hollow 
tubes, called 'nervurcs,' 
aloag which branches of 
the trachoc and channels 
of the circulation are con- 
tinued."— (Owen.) Ac- 
cording (o Newjwrt, the 
wingi of Insects arc '" expanded portions of the common in- 
tegument of the sides of the me«o-and tnct3-thor:tx,orc3sioncd 
tir the enlargement and extension of numerous trachcte and 
tlic accompanying passages for the circulatory tltiids, and their 
motions are intimately connected with ihc function of resplia- 
In tlw Colaftera (Beetles) the anterior pair of wings 







tht fitn ^it HI ■(■•: < MtwihiiTM. uirrtni 



rs 



lilruihorvx. »ith the ihitA |4Jr o' \tt^ anq ch* 
rrpffAduciioa. 




250 



MANUAL OF 200I.OCV. 



become hardened by the deposition of diitine, so as to fom 
two prorective cues for the hinder ntembntnons wing$. la 
this condition the anterior win« are known as the " clytn,* «r 
"mng<:ists." In tome of the Haitifitfra this chunge on^ 
affects the inner portions of the nntenor wings, the apices li 
which rcmnin membranous, nnd to these the term "hemel^' 
is applied. In the Diptertt the posterior pair of wings are 
rudimcnUry, and are converted into two ca])it2te fibawsli, 
called "haltacs," or "balancers," In the Strtpafttn Ike 
anterior pair of wings are rudimentar)-, and are converted iaM 
twisted libmetitx. 

The ]>riiniiive number of somite* In the abdomen of insects 
is said to he eleven ( Orihoftera), but nine is the number ocdi- 
n.irlly present ; and tliongh these are distinct in nwst lan-x, ii b 
seldom that more than seven or eight arc reooignbaMe in llw 
adult I'hc abdominal somites are usually more or leu fredy 
movable upon one another, and never cany locomotire limb). 
The extremity of the abdomen is, boirever, not infretineath 
furnished will) appendages, which are connected with ibc 
generative function, and not infrequently serve as offeniire 
and defensive weapons. Of this nature are the ovipositonof 
Ichneumons and other Insects, and the tting of Bees ud 
Wasps. In the Earwig {^rfieula) these caudal appeni 
fonn a pair of forceps ; whilst in many Insects they ore i _ 
form of bristles, by which powrerful leaps can be effected, m 
seen in the Si>Tingtails {Pfidurts). In some insects (as tbt 
MoleKnicket and Cockroach), the 9th or toth abdoml 
ment carries jointed antcnniform ajipendaaes, which, 
perhaps p.irtinlly or even primarily generative in function, U* 
certainly oi^ns of sense, being connected with smell or 
hearing. 

The organs about the mouth in Insects are collectiidy 
termed the " tiophi," or " instnimcnta cibaria." Two prindpiJ 
types re{|Uirc consideration — namely, the masticator}' and tlie 
BUcUwial — ^boih types being sometimes modified, and occa^oo- 
ally combined. 

In the Masticatory Insects, audi as tlie Deeiles (fig. S4, i\, 
the trophi consist of the following parts, from before bad- 
ward.t; — (1.) An upper lip. or " labnim," atUched Iwlow tht 
front of the head, (i.) A pair of biting-jaws, or " mamlihles." 
(3) A pair of chewing-jaws, or "maxillfc," provide<J uiih one 
or more pairs of "maxillaiy palps," or scnsoty and ttctile 
filaments. (4.) A lower lip, or "labium," composed of » 
second coalescent pair of maxill.'c, and abo bearii^ a pair of 
p^pi, the " labial palps." The primitii-e fom of the labiiBD, 




ANNUL05A: INSECTA. 



251 



llut, namely, of a second pair of nuutiUx, is more or less per- 
fwily rctiiinixl by llie OrtAopttra an<i some of the Neurofitra. 
1'hc lovrcr or biual ponion of the Li1>ium is called the " men- 
bun " or chin, whibt the upper portion it more Bexible, and is 
lermed the "ligula." The upper portion of the li^la is often 
develo|>ed into a kind of ton^, which is very distinct in some 
Insects, and is termed the "Itogua." 





h 



ris. !«. — "nim ff llii m •' 1 I • •" i Tnnhisf iisuliaclnc liucel IUcctlc): 
~ ' %t\^\h U]incJ;1]tc«, f hffttiljjv *iih IhAt j«lpi : V L>)4uin of 

I 4 Srini »unV«> ' uilui ' ^ M«ulb eT ■ Jlsai|ilsvu» liuKi <A'i)M 



ih ill I ' 



tvnr »|> villi i 



: ■■• M»:iiIlK ; ■ TkUndiblA. 



In the (yptcal nietorial motilh, as seen in the Butterflies 
(fig. 84, 3), the following is the .irrangctncnt of parts : — The 
labnuD and the mandibles are now quite ntdimcntary ; tlie 
first pair of maxilla: is greatly elongated, each maxilla forming 
k half-tube. These maxillae adhere together by their inner 
unbces, and ifaua form a spiral "inink," or "antLia" (in.ippn>. 
prnicly called the " proboscb "), by whidi the juii:eK of flowers 
are tucked up. Kadi maxilla, besides the half-tube on one 
side, contaiat alio a tube in itH interior ; consequently on a 
tnnsvene section the trunk h found really to consist of three 
canals, one in the anterior of eadi maxilla, and the third formed 
between them by their .-ipposilion. To the base of the Iniiik 
arc aiiachcd the maxillary palpi, which arc extremely small. 
Behind the trunk is a small labium, composed of the united 
iGcond pair of maxillse. The "labial palpi" are greatly devel- 
Of)cd, and form two hairy cushions, between whidi the trunk 
is coiled up when noi in use. 

In the lice there exists an intermediate condition of partly 
the OKKith being fitted partly for biling and jartly for suction. 
Thfl kbram and mandibles are well developed, and reuin thor 




352 



MANUAL OF ZOOLOCV. 



usual form. The muillx and t)ie labium are greatly 
gated ; the former being apposed to the lengtlicned tongue a 
such A manner as to lunn a tubtilar tnink, whirh cannot be 
rolled up, as in the ButtcrDics, but is capable of effidcut sue- 
lion. The Ubtal palpi arc also greatly elongated. 

In HiQ //fiififfra, the "irophi" consist of four lancet-sliapcd 
needles, which arc the modiiicd mandibles and nuxiUc, co- 
closed in a tubular sheath fonncd by the elongated bbiiui 
(fig^ &4, 3). Lastly, in the Diptera — as in the common Hoim- 
fly— there is an elongated labium, which is channelled on its 
upper surface for the reception of the mandiblex and mauUc; 
these being modified into bristles or lanceix. 

The mouth in the Mnsticating Insects leads by a phaipi 
and ccsophagiis into a membranous, usually folded, Uonadt 
— Uie "crop," or "ingluvies" — from which the food is txani- 

mined to 3 second mtucnbt 
stomach, called the "^uaid* 
(fig. 85), ThegiKunl isadift- 
cd for cnisliinjf ilie food, omn 
having plates or teeth of chitine 
developed in itt walls, and ij 
succeeded by the true digctrin 
cavity, called the " chytiftc sto- 
mach" {vfMtrUuiut ekjl^pe*^- 
tvi\. From this an intetbae 
of variable length jtroccedt, lis 
terminal portion, or rectum, 
opening into a dilatation whkh 
is common to the ducts of the 
generative organs, and is termed 
the " cloaca.' The o»opbagiis 
{(furnished with salivary glasdi 
of var)-ing !>iie and oomplenty, 
and i« jMovided in some of tkc 
Suctorial Insects with a dilata- 
tion called the "sucking «> 
mach." Behind the pyloric 
apcnurc of the stomach, wiii 
very few exccptioni, are a vaii- 
able number of rascal, como-. 
luted Itibes (fig. 85. t), whidi 
open into the interline, and are 
called the '■ Maljiighian tubes.' 
as representing the liver, bjll 
arc by some believed to have a renal function. If the MaJjiig- 




He ■).— Difwdnc tftxa nt ■ limit 

Crop-, t r.iianl. VChfliAc iinniAchL 
f Hilpllurin Iul>aj / lotttiiH: t 
GoM&J ■ Sujv***^ »ul vcucla. 

These arc often looked upon 



I 





ANNULOSA : INSECTA. 

truly perform the functions of x liver — as Iheir 
position «-ould appear to prove — then the kidneys will be 
represented by a series of cajcal tubes which arc only occa- 
sionally present, and which open into Ihc rectum, close to the 
cloaca. There are no absorbent vessL-l^ and tlic products of 
digestion itimply traiuude through tlie wall.s uf the alimentary 
caoa] into (he sinuses or irr^ilar cavitiw which exi.tt between 
the atxlomiiMl or^ns. The apjiarattis of digestion does not 
dtflier essentially from the above in .iny of Ihc Insects ; but the 
alimcntar)- canal is, generally speaking, considerably tengthcne<l 
in the herbivorous species. 

There is no definite and regular course of the circulation in 
the Itisects. The ]m)pulnve organ of the circulation is a long 
contiactQe cavity, situated in the back 3n<l tcraiL-tl the " dor^l 
vessel" This is composed of a number of sacs (ordinarily 
eifi^t), opening into one another by valvular apcrtiire?), which 
allow of a cturcnt in one direction only — vi/..towariU the head. 
'llie blood is collected from the irregular venous sinuses which 
are formed by the lacunic and interstices between the tissues, 
and enters the dorsal vessel from behind ; it is then driven 
forwards, and b expelled at the anterior extremity of the body. 

Respiration is eilectefl by nieans of " trachex," or branched 
tubes, which oommencc at the surface of the body by lateral 
a|>erturcs called " stigmata," or " spiracles," and ramify through 
every part ot the animal. In structure the tracheae arc mem- 
branous, btit their walls are strengthened by a chitinous fita- 
iDcnt, which is rolled up into a continuous spiral coil. In 
the aquatic larvs of many insects, and in one adult insect, 
branches of the Iracheie are sent lu icmjiorary outgrowths 
which are termed "traeheal gills," and in which the blood is 
Oxygcnate<L In all, however, except the single inject above 
iDcniicMied, these tcmponity cxtcni.il appendages fall off when 
raotunty is attained. 'I'be wings, also, whilst acting a.s luco- 
tDolive organs, dmibtless subserve respiration, the ncrvures 
being hollow tubes enclosing trachea;. 

The nervous system in Insects, though often concentrated 
into special masses, consists essentially of a chain of ganglia, 
placed venlrally, and united together by a scries of double 
oonls or commissures. The cephalic or " pne-wsophageal " 
gUtglit ore of laree size, and distnbute filaments to the eyes 
and antenMC The ]>ost-cesophageal ganglia arc united to the 
preceding by cords which form a collar txnmd the gullet, and 
they supply the nerves to the mouth, whilst the next three 
fprnglta furnish the nerves to tlic legs and wingi. In lame^ 
Ihirteeo pairs of gar^jlia, one to ea!di scgmcDl, con be recog- 




254 MANUAL OF ZOOLOGY. 

nised. In the imago, however, of the Colafiera, seven! of 
these primitive ganglia have coalesced, so that this Dumba ii 
considerably reduced. 

The organs of sense are the eyes and antentue. The eja 
in Insects are usually "compound," and are composed trfi 
number of hexagonal lenses, united t<%ether, and each supjditd 
with a separate nervous filament Besides these, simple tju 
— "ocelli," or "stemmata" — are often present, or, in mt 
cases, may be the sole organs of vision. In structure these 
resemble the single elements of the compound eyes. In i fe> 
cases the eyes are placed at the extremities of stalks or ped- 
uncles, but in no case are these peduncles movably articulated 
to the head, as is the case in the Podophthalmous Ciustacou- 
The antennae are movable, jointed tilainents, attached nioil^ 
close to the eyes, and varying much in shape in difleient In- 
jects. They doubtless discharge the functions of tactile orgaiu; 
but are probably the organ of other more reramditc senses b 
addition. 

The sexes in Insects are in different individuals, and most 
are oviparous. Generally speaking, the young insect is voj 
different in external characters from the adult, and it requirei 
to pass through a series of changes, which constitute the "meta- 
morphosis," before attaining maturity. In some Insects, hcnr- 
evor, there appears to be no metamorphosis, and in some &e 
changes which take place are not so striking or so complete as 
in others. By the absence of metamorphosis, or by the d^iee 
of its completeness when present. Insects are divided into 
sections, called respectively AmetaMa, HemimdaMa, and 
Jfiflometitboia, which, though not, perhaps, of a very high sdst- 
tific value, are nevertheless very convenient in practice. 

Sfcfiim I. AmeiiiMU InsKls. — These pass through no meta- 
morphosis, and also, in the mature condition, are destitute of 
wings. The young of these insects {Apterci) on escaping from 
the o\'um resemble their parents in all respects except in size; 
and though they may change their skins frequently, they undogo 
no alteration before reaching the perfect condition, except thai 
they grow larger. 

Sedion a. Hemimrtabeiie Inseds. — In the insects belonging 
to this section there is a metamorphosis consisting of uree 
stages. The j"oung on escaping from the ovum is termed the 
"Iar^^:" when it reaches its second stage it is called the 
" pupa," or " n>-niph :" and in its third stage, as a perfect 
insect, it is called the " imago." In the HfmimaaMa, the 
" lana," though of course much smaller than the adul^ or 
" imago," differs from it in litde else except in the absence of 




ANNULOSA: INSECTA. 

Ingfc It is active and locomotive, and is generally very like 
the adult in nternal appearance. 'I'hc " [lujiu," again, is a 
iitde brgcr than the Urva, but really iliH'ert frutn it in nothing 
eIxc than in the £nct thai the rudimctils of wings have now 
appealed, in the form of lobes cnrloscd in cases, llic " pupa " 
H still active and locomolivc, and the term " D}-mph " is usually 
tp{)licd to it. Tlic pupa is converted into the perfect insect, 
or " iina{;o,' by the liberation of the wings, no other change 
being requisilc for this purpose. Prom the comparatively «mall 
unount of ilifTcience between these tiiree stages, and Erom the 
ictive condition of ihe piiju, this kind of melamoiiihosis ia 
■id to be "incomplete." 

In some members of this section however— sudi as the 
[>ngon-6ic« — the larva and ptips aic aquatic, whereas the 
inaagD leads an aerial life. In these cases there is necessarily 
I consideTable difference between the larva and tlic adult ; but 
:lie fauva and pupa are c!osely alike, and the latter is active. 

•SaY/rmn 3. /iolDmetaiolk Instcti. — TIicnc — comprising the 
Butterflies. Moths. Beetles, vtc— paM through three stages 
vhich differ greatly from one 
another in appearance, the 
netamorphosts therefore, be- 
ng sud to be "complete." 
n these insects (% 86) the 
'larva" Lt vennilorm, seg- 
nented, and usually providcil 
nth locomotive feet, which 
lo not cotrcspond with those 
if the adul^ though these 
alter arc usually present as 
rcU (fig, 86). In some cases 
he lam b destitute of l<^ 
IT b "apodal" The larva is 
hn provided with matlica- 
Ory M^pUM, and usually eats 
oracioutly. In this &tagc of 
lie metamorphosis the Unrvaa 
ooititutc what arc usually 
ailed " caterpillars " a»d 
gruhs." Having remained 

\ this condition for a longer Tf. k— Mfuin.)iiJ>u;< m ihi Miow- 
borter length of lime, and '*"' i''*'^—*^"/'"-*-* 

undergone repeated changes of skin, or "moults," ne- 
' by lis rapid growth, the Urva passes into the second 
and becomes a " pupa." The insect is now perfectly 





256 



MANUAL OF ZOOLOGY. 



quiescent unless touchml or othcnrise irrit&tcd ; is incapable cJ 
dunging its place; and U often alUchcd to some foreign ohjto. 
Thia constitutes what — in the case of the Z^fiidoftxra — a pnc^ 
rally known aji the "chrysalis," ot "aurelia" (fig. 93). Tie 
Ixxl)^ of the [)Up3 is usually covered by a chJcinoux pelbck, 
which closely investN the njiimzl. In some izaxn (ifg., in raoajp 
Dipieroiii in.sccts) no t»ccs can be detected in the pupa of the 
fuitiTc in.^ect ; but in the I.epidoftera the thorax and abdocncB 
are distinctly recognisable in the pupte ; whilst in others {t.(., 
Hymtntflera) the parts of the pupa are merely covered by s 
membrane and are quite distinct. In some casc& the pupa is 
further protected within the dried skin of the larva ; and ia 
other cases the larva — immediately before entering upon the 
pupa-stage — spins, by means of special organs for the purpose, 
a |)ro[eclive <^i*e, which surrounds the chrysalis, and is icrmed 
the •* cocoon." 

Having remained for a variable time in the quiescent pupS' 
stage, and having undergone the necessary development, the 
insect now frees itself from the envelope which obscured K, 
and appears as the perfect adult, or *' ittago," characterised by 
the ]>oase3ston of wings. 

SF.XK.S ov Insects. — The great majorit)- of Insects, as is tbc 
rase with most of the higher animals, consist of male and 
female individuals) but there octva some striking exccpitkiu 
to this rule, .is seen in the Social Insects. In those organised 
communities which are fonned by Bees, Ants, and TctmiW, 
by far the greater number of the individuals which compose 
the colony are either undeveloped femalei^ or are of no ftill)' 
develo)>ed »cx. This is the case with tlie workers amooga 
Bees, and the workers and soldiers amongst .Ants and Termites. 
And these sterile tndividuaU, or "neuters," ;« they ore eo«B- 
monly called, are not necessarily all alike in structure and 
external appearance. Amongst the Bees all the neuters r^ 
scmblc one another ; but amongst Ants and Tcrmilcs they are 
ol^cn divided into " castes," which have different functions to 
perform in the general polity, and differ from one anocber 
greatly in their characters. 

In all the above-mentioned insects the nules are reliertd 
from the performance of any of the duties of life excejH tliti 
of proiugaling the species ; and the females — wliidi are gene- 
rally solitary in each community — fulfil no other function utc 
that of laying eggs. All the other duties which arc neccuBT 
for the existence of the coinmtmiiy are perfonncd by ^ 
workers, or ncutcre. 

The organs of the t<NO vasx. are in no case united in ^ 





, or, in other n-ord^ there arc no hermaphro- 
r^In some wry abnorraul cases amongxt Bees 
aphrodite indivitliiaU have been observed.) As ou been 
ed, hovrcver, before, asexual reprodnction is by no means 
Dwa anwngu the /nteaa, and the attcndaot phenomena 
Ikcn of eictieine inleresi.— (Sec Inlroduciion,) 
Ib great majority of insects, during their adutt condition, 
ITKstrial or aeruil in their habits, but in many cases, even 
)M. the lor^-a; are a(|uati<:. Many other insects live habit- 
jdnring all stages of iheir exi%[i.-nce in fresh water. A few 
p inhabit nb water (cither the nca it.sclf or inland salt 
a) during the whole or a portion of their existence, (Thi* 
I case with two or three Deciles of the families Ilydrophi- 
bkd DytUada, some Hcmipicrous Insects, and the \s,x\3i 
|riou3 Dipiera.) Lastly, many insccis live parasiiically 
'He bodies of Birds or Mammals, or upon other Insects. 



CHAPTER XL. 



, ud 



DIVISrOiWS OF mSBCTA. 

Imtttta includes such an enormous number of species, 

Eunilics, that It would be impossible to treat of 

"\y otherwise ihao in a treatise especially dc- 

to Emoniology. Here it will be sufficient lo give 

the differential characters of the diffeicni orders, draw- 

tion occasionally to any of the n)ore important points 

witli any jtiven family. 

\y said, the Jnsttfo are divided into three divisions, 

imtiahola, Hemimtiah-^a, an<l Ha/omdaMa, according 

y attain the adult condition without passing through a 

tor^ihosis, or have an incomplete or complete mciamor- 

. 'rite Insects which come under the first head (vii. 

1Mb) are not furnished with wings in the adull condition, 

pc three orders which compose this section are com- 

imiouDed tofjether under tlic name Af^era. By some, 

ttr, this division '\» entirely rcjeaed. and ttie three orders 

jcuioa ore [ilace<l amongst t)ie Htmimtt^cta, or ercn 

' with the Myria^'fa. 

sx I. AMerAii(H.A. — YauHg nrt filing lAtvt^h a 
it, ainf difffrinsfr^m thf aduU in siu mty. Imaffi 
Wii^,- /^/Si^/Za i^me/ima wanting. 
R 




2S8 MANUAL OF ZOOLOGV. 

Order I. Anoplura. — Minute Apttra, in wbich the moiil}i 
is formed for suction; and there aic two simple eyes, v 
none. 

This order comprises insects which are commonly pansitic 
upon man and other animals, and are known as Lice {PedUitli^ 
The common Louse is furnished with a simple eye, or ocdliu, 
on each side of a distinctly differentiated head, the under sur- 
face of which bears a suctorial mouth. There is little distinc- 
tion between the thorax and abdomen, but the s^ments of 
the former cany three pairs of legs. The legs are short, with 
short claws or with two opposing hooks, a&brding a very &m 
hold. The body is flattened and nearly transparent, composed 
of eleven or twelve distinct segments, and showing the st^ 
mata very plainly. The young pass through no metamorphose 
and their multiplication is extremely rapid. Most, if not ill, 
Mammals are infested by Lice, each having genemlly its om 
peculiar species, and sometimes having two or three. Three 
species are said to belong to Man — viz., Pedkulus humamt, 
P. capitis, and P. pubis. 

Order II. Mallophaga. — Minute Aptera, in which the 
mouth is formed for biting, and is furnished with mandibles 
and maxillK. 

The members of this order are commonly known as "Bird- 
lice," being parasitic, sometimes upon Mammals, but mostif 
upon Birds. They strongly resemble the Pedieuli, but die 
mouth is formed for biting, to suit their mode of life — since 
they do not live upon the juices of their hosts, but upon Ibe 
more delicate teguraentary appendages. 

Order III. Thvsanijra. — Apterous insects, usually with a 
masticatory mouth, and having the extremity of the abdoinra 
furnished with locomotive appendages. 

The most familiar members of this order are the /Www, « 
" Spring-tails," which are characterised by the possession of > 
forked caudal appendage, by the extension of which consider- 
able leaps can be effected. In the nearly allied Lepisma, loov 
motion is assisted by caudal bristles. In both, the body ^ 
covered with hairs or scales, the structure of the latter bang 
often very beautiful. 

Sun-CLASS II. Hf.mimktaboia — Metamorphosis inampt^l 
the larva differing from the imago chiefly iit the adse/iee ofwiup, 
and in size; pupa usually active, or, if quiescent, capable of nwet- 
ment." 

* The Cotcidj, airninjpit the Htmifltra, underp) a complete meliawf- 
phoais. In certain of tlie ILmiflfra and Orlhoplera [he adult is iplertm 
and in these case& xheie cutiuA \>e wA Vi \ik *,'&-« -ciLstunorphosu, nntt 



annulosa: insecta. 



359 



I^*. Hemiftbra. — Mouth suctorial. bcak-xhnp«I, 
ft jouilcd rc&tnim, composed of the elongated 





IkiM Aflm iA/iii/aU). vlncc^ naif uut virKleH finile. 

Itch rorois 3 jointed, tubular sheath for ihc brisllc- 
^ItfonD mandiblea and maxUlx. Eyes compound, 
llh ocelli as 11-ell. Two 

Kio mosii sometimes 
I Hvc upon the jtiices 
3f animals, which they are 
> obtain by means o^ the 
istTunL Amongst the more 
camples of this order are 
lice {ApMida, fig. 87), iht 
{Ftnial^ma). the Hoat-dy 
It the Cochineal Inxectx 
i the Cicadas. 'I'hc order 
into the following two 

rder a. fftrmtftsra, — ^The 
erioT pail of vrtngs of the 
ne texture throu^^out 
nnbranoux) ; tlte moutli 
ned liackwards, so tlul 

beak springs from the 
* of the head. Thew-ings 
I over one another when 

tasect is at rcsL 'i'hc 
ee tepnents of the thorax 
uaited in n mju^s and the 
-thor^LX iK generill)' sliortcr 
Q the mcso-thorax. There 

Jrr (rom ihe »ilult onlj in sue. in hftvinc fewer joinls (o Ibe 
d in Iift*ln£ ■ ismIUt nmnlKi' of fleet* in CMck ot lUe ion- 




Fl( It.— OKhcMin. Tli( cdiA- 




26o MANUAL OF ZOOLOGY. 

are ocelli between the compound eyes, and the antenu 
are small and composed of few joints. The femila 
have an ovipositor of three toothed blades. In diis 
section are the Aphides, the Scale Insects {Ceidde), 
the Cicadas, the Lantern-flies (Fu/gora), &c 
Sub-orda- b. Heteroptera. — Anterior wings membranons 
near their apices, but chitinous towaids the base 
(hcmelytra) ; the rostrum springing from the front of 
the head. The inner mai^ns of the wings are stiai^t 
or contiguous. The antennae are moderate in size, hL 
composed of a few ta^e joints. The pro-thorax is the 
largest segment of the thorax. They are divided into 
the two groups of the Hydrocarisa (Water-bugs) and 
Geocorisa (Land-bugs), according as they are aquatic at 
mainly terrestiiat in their habits. 
Order V. Orthoptera. — Mouth masticatory; wings fooi, 
sometimes wanting; tne anterior pair mostly sinaller tlun ^ 
posterior, semi -coriaceous or leathery, usually with numcno 
nervures, the interspaces between which are filled with mairf 
transverse reticulations; sometimes overlapping horizontallr 
(Cockroach), sometimes meeting like the roof of a hoose 
(Grasshoppers). Posterior wings usually having th«r bout 
portion of a different texture from their hinder portion, thij 
latter being almost always more transparent, and when not m 
use, folded longitudinally like a fan. Posterior wings mostly 
wanting in the females of the Biattida. Antennx usuaQf 
filiform. Metamorphosis semi-incomplete (sometimes, how- 
ever, the adult is apterous, when it becomes almost impossiHe 
to distinguish the larva, pupa, and imago). 

This order includes the Crickets {Achaina), Grasshoj^ns 
{Gryliina), Locusts (Locitslina), Cockroach^ (Blatiina, fig. 88), 
&c. Some of them are formed for running {curseriat^, sill the 
legs being nearly equal in size ; whilst in others the first jair 
of legs are greatly developed, and form powerful rapitm*! 
organs, as in the Mantis. In others, again, as in the Gtas^ 
hoppers and Crickets, the hindmost pair of legs are greatlf 
elongated, so as to give a considerable power of leapii^ to 
them. All the Orthoptera are extremely voracious, and tbe 
ravages caused by locusts in hot countries are well known to 
all. The most destnictive of the Locusts is the Migratoty 
Locust {Aerydium »ii;^aloriiim, fig. 8g) of Africa and Soulhem 
Asia, This formidable species is celebrated for the destnic 
tion which it cau.ses in certain seasons in the countriw i" , 
which it occurs, a destruction against which human an h» i 
hitherto proved w\io\\\ ^owetXe^v Na».V«wles of thisspecio 



ANNULOSA: INSECTA. 



361 




ftc H—MIcmcty Lacuin l^tryMitm mit 



AnrcnA suddenly upon s district, nnd in a few boure destroy 
all cTO{>s, and devour the leaves of all the trees, migraiing as 
suddenly as they caroe, so sooo as the ground is utterly ban: 



^VOkdfr VI. NEt'xoi-TiEKA. — Mouth UHuull)' matlicatOTy; 
Inn^ four in number, all membranous, generally nearly equal 
in Stic, traversed by Dumeraus delicate nervurcs, having a 
loRgitadinat and tmnsverse 
dirrclion, and giving them a 
reticuUled, Uce-like a«|)C4:t. 
Melaintiq>hnsii generally in- 
cotnptcle, rarely complete. 
The larva active, hcxapod, 
larely with pro-legs. 

This order inchides the 
Dragon - ftics {LrMluiidie), 
Caddis-flies {Phr}f;iiHeida), 
Hay-flies {Effirmeru/a)* the 
Ant-lion {Afyrmflfo). Ter- 
tnitdt. A:c. 'I^ic bst of ibese 
—namely, the Termiics or 
White Ants — are social, and 
Eive in cumm unities, and their 
habits are so sinj^lar that a 
ihon description of them will 

not be out of i^ace here^ lliey arc mostly inhabitants or hot 
rounirics, where thcj- are commonly known as " White Ants ; " 
Imt Tt mtiu l>e borne in mind that they have nothing to do 
with the insects commonly called Ants, which belong, indeed, 
to a different order {fiymenoftera). The following aocouni is 

* By tnoke the DncM-lic* {/.UtOitliitt), the Mar-Ait* {BfAtmfnit\ 
tnl ibe TemilM {TermilU^, ire pUetil in ihr Orlivftrra, under tae 
irwmm mhi* or futKh-nnrrfim ; whilit Ifac CattilU-ftlct i.nryg*tiMtl\ 
tana a MiNuaif onlw nodn- iA# tune of TrUA^eru. 






rif. «» — NmmpUf*. AphtallM (Ml 
11*11* fl. inafo. luvi, and , 



262 



MANUAL OP ZOOIMSV. 



taken from Kir Batch's work on llic Atnaions, where Uictt ii 
an excellent dncriiition of the habiu of these remaikiUt 
insects- 

TrrmiUs are small, «ofl-1>odi«l inteds, whidi liv« in laip 
communities, as do the true Ants. They differ, howc^vr, liOB 
the AniB in the fact that the workccs arc indii-idiials of ne 
fully developed sex, whereas amongst the Inttcr iJjcy are llad^ 
veloped femaleii. Further, the neuters of the Termtics n 
ahirayi composed of two distinct dasses or "castes"— (he 
worken an<l the soldiers. ^Mitiy, the Aou under^io a <iuiaceoi 
pupa-stage ; whereas the young 'I'cnnilM, on their vmvr^na 
from the egg, do not differ from the adult in any respect cxcq< 
to si^e. 



I 




^ i 



viih ihi abd'imen <ll>iciiajid villi iSf>; < Wofiw: ^SeUia. I 

Each spcrics of Termites conxisis of several distittd ontes I 
or castes, which live together, .ind constitute powlotu, 9-\ 
ganiscd communities. They inhabit stnicttircs Known ol 
" Termitaria," consisting of mounds or hillocks, M>ine ()f whidij 
»rc " five feet high, and are formed of particles of earth wcifc«d j 
into a materia] as hard as stone." The Tcrmitarium hai v\ 
external aperture for ingress or egress, as far as can \k ttrt, 
the entrance being ]>laced at some distance, and conncdcJ 
with the central huilding \>y means of covered ways "^ 
galleries. Each Tcrmilariiim i* composed of " a v»$l no* 
ber of chambers and irrcgubt inlercommunicating galloM^ 
built up with particles of earth or vegetable matter. cenMlilal 1 
together wriih the saliva of the insects." Many of "the tori 
Urge hillocks aic vYie'woiW ot nu.«) ^isMacA s^des, each d\ 



ANNULOSA: INSKCTA. 



263 



id) nsei fnatemis dilTcrratly compacted, and keeps to its 
nm poniuo of the tumulus," 

A family of Termites coDsiat.t of a king tad queen, of the 
rorken, and of the NOidiLTs. The royal cou|)le arc the jutrenU 
if the colony, and "' aic alvray* kept together, closely guarded 
ly K detachrocnl of workctr. in a l.wgc chamber in the very 
lean of the hive, «irroiinded by much stronger walls than the 
tthw cells. They arc both wingless, and immensely larger 
han the workers and soldiers. The queen, when in her 
J^mber, is always found in a gravid condition, her abdomen 
tnonnously distended with eKi$s, which, as fast as they come 
brth, are conveyed by a relay of workers in their mouths 
rom the royal chamber to the minor cells dispersed through 
he hive." 

At the bcgimiing of the rainy se^tson a, number of toiifgeJ 
lulcs and females are produced, which, when they arrive st 
oaturity, leave ihc hive, and fly abroad. They then shed their 
rings (a special provUion for this existing in a natural seam 
■aaing acros* the root of t!ie wing and dividing the nervures); 
hey pair, and then become the kings and qucen-t of future 
olonirs. 

The workers and the soldiers are distinct from the moment 
if their emergence from the egg, and they do not acquire 
heir special characteristics in consecguence of any difference 
€ (ood or treatment. Both are wingless, and they differ solely 
A the armature of the head 'I'he duties of the workers are to 
' build, make covered roods, nurse the young brood from the 
gg npwanb, take care of the king and queen, who ore the 
irogeniiois of the whole colony, and secure the exit of the 
nales and females when they acquire wings and 6y out to 
tair and dis%minatc ihc race." The duties of the soldiers are 
o defend Ihc community from all attacks whicli may t>e made 
ipon its peace, for which pur|)ose the mandibles are greatly 
leveioped. 

It may well he admitted, that in such organised rommumiies 
;■ those of the Termites, we have the highest development of 
mect-life }'ct known to iun. I'he principle of the division of 
abour is carried out to its fullest extent — much further, indeed, 
han is possible amongst human beings, — since the perfection 
4 the greater number of the individuals which compose the 
mnnmaity — as organisms — b sacrificed in or>lcr to secure the 
ulfifanem of the duties which are ncccsrar}- for the existence 
nd wcltarc of the whole. Even the task of perpetuating the 
peciet. and of giving origin to fresh colonics, is cniircly left 
ODC cbn of the community, the defence and p^uiccvvoTi cA 




364 



MAKUAL OF ZOOLOGY. 



which a ihe special object and care of the remainder. No 
higher development could well be inugined amongst creatuKJ 
devoid of the higher ]»ychical endowments ; and it is tKx&j 
of note ihnt st least three distinct and independent families of 
Insects have attained to this stage — namely, the Tennites, the 
Bees, and the true Ants. 

SuB-CLABs III. HoLOMETABOU. — Mttamorpkotu evmfki; 
ike ian.-a,fufa, and imagu difftringgrraifyfrtm me andher m tx- 
ttrnal apfearan^t. The hn'a trrmi/^m, and the pupa fuietceii. 

OxDFJt Vll. Aphaniptkra. — VMngs mditnentary, in tbt 
fonn of plates, situated on tlie meso-thorax and meu-thoru. 
Mouth suctorial. Metamoq^hosis eompt«t& 

This order comprises the Fleas {Pu/ieida), most of «liicb 
ate parasitic upon dilTcient animals. The lan-a of the cottUMa 
Fie* is an apodal grub, which in about twelve days spins ■ 
cocoon for itself, and becomes a quiescent pupa, from which 
the imago emerges in about a fortnight mote. Besides the 
common Flea {Pukx irritans), anotlier well-known at>d coo- 
sidembly more troublesome member of this order is the Chigoe 
{Pultx pfiutrani) of the West In<lics and South Amcnca. 

Order VIII. Dirri^RA. — The anterior pair of winj^ atooe 
de^■elopcd ; the posterior pair of wings rudimentary-, re- 
presented by a pair of clubbed filaments, called "hal- 
teres," or "balancers" (A^. 92X In a few the wings aie 
altogether wantinf[. Mouth suctorial. The metamorphoiis 
U complete, tlie larvge being generally destitute of feet \ b«i 
in some cascs {f.g-, the gnats) the pupx are aquatic and an 
actively locomotive. In most cascSi however, the pupcc an 
quiescent. 

I'he proboscis in the X>ift<ra consists of a tubular labioiii, 
enclosing the other pirts of the mouth, and is placed on ihe 
under surface of the head. Ocelli are present in addition 10 
the compound eyes. Tlie wings are generally liorizootal and 
tnuisparvnt, the nervures not very numerous, and for the noB 
port longitudinally disposed. The aiitcnnn: arc genoaPf 
small and Ihrcc-jointed, sometimes nuny-)ointcd {"Hpuikk), 
or feathery { CuUeida:). I'he brva is soft and fleshy, willi 1 
sol) indistinct head, usually apodal, never wiili thomdc Icm 
and rarely with pro-legs. The larval sicin mostly fonw * 
hardennl case for the pupa, but the larvse sometimes at 
their skin when becoming pupse, or even »i>in cocootu. la 
some the eggs are haidied n-ithin the body of the mother, to 
that the insect ap|>caTs firtt in the larval state ; and in /'n^^fit 
not only is this the case, but the larvie continue to reside wiib- 
ia the mothei until lix^ ViecAmi^'vn.v)^ 



w 

!■ The DiM 



ANNUIX)SA: INSECTA. 36$ 



. hf Dipttra wwtSinile ot\k of the largeu of ihc orden of 
the littfcta; the H<ws«-flies and nc^-flit* (Muua), Gnats 
(Ciwfcr), ro»e«-flic8 i,Hiffolmea), Crane-flies (Ti/u/ida), and 
GwMicB (TbAiAMfo), coniititutiDg good examples. 




fir }^— DIpMn. CnmSriTifuUttinnml 

Order IX. Lepidoptera. — Mouth suctorist, consisting of 

■innl tnink or " antlia," composed of the grcally-clongated 
"iBUcitfae, and protected, when not in me, by the cushion 'sha]>ed 
hftiiy labial palpi. Maxillx foriniiif; two sub-cylindrinl tulMS, 
uiled together by inonnilniing hooks, nnd constituting an to* 
tenacdiate tuhe hy their jtinctioa. Maxillary palpi minute ; 
Ubruro and manthbles rodimcntary. Head, thorax, and ab- 
domen more or less covered with hair. Wings, fwir in niim- 
hu, covered with modified hairs or scales ; wanting in the 
fcmalea erf a few species. Ncnmcs not vct^- numerous, mostly 
kxtgiludinal Antenna: almost always distinct, and composed 
of numerous minute joints. 

litis well-known an<l roost beautiful of all tlic orders of 
Jmects compriKes the Butterflies (Ag. 9.{) and ihe Moths (li^ 
94} ; the rormcr being diumal in their hiibits, the latter nioslly 
cr^tucular or nocturnal. 

The birrae of Ltpidaftera (lig. 94), commonly railed "cater^ 
pfflan," arc vermifono in shape, norm.illy composed of thineea 
aqpnoMa, the antenor poituui fomting a diiitioa \\oinf \wA&t 



s66 



MANUAL OP ZOOLOGV. 



with antennae, Jaws, and usuall)- simple tyes. The mouUi of 
the c-tterpillar, unlike that ul' the perfect insect, is forrned for 
mavlirjition. The labium alxo ii provided with a tubuhr or^^a 
— llic "spinneret" — which communicatet with two inioiul 
glands, the functions of which are to fiimii>h the iiik, wh<r^ 
the animal constructs its ordinji>' abode or «pins its cocoon. 
The three segments behind the head correspond with the pro- 
thorax, meso-thorax, and mcta-thorax of the perfect insect, la-l 
each cairies a juir of jointed n-al king -tegs. Besides thrK 
thoradc legs, there is a variable number, (generatly ten) of tot 
fleshy Icus, which are bomc by the segments of tlie abdomoi. 
and are known as " pro-tegs." F.3Ch is usually furnished wii 
El crown of small homy hooks, and the}' are never attadxd la 
the 4lh, sih, lolh, and ttth abdominal segments. 




nc-n,— laiicWhiHCitibueButttrflrtfnCMfraa^). atirnnt UU I^- 
t I'lifaer chiyiBlii; t tucn sr p*rfM Inaci. 

In tlie Diurnal J^pUofttra. or Butterllics proper (fifr ^h 
the antenna: arc knobbed ; the wings arc tisiial^ held *?*'i 
when the insect is in a state of repose; the larvx havfs^ 
thoracic legs, and ten pro-legs ; and the pupa; arc al' 
naked, attached by the posterior extremity or head downwart** 
and usually angular. 

In tlic Crejiuscubr Lepiiicfitera, including tliose forms whid* 
an active durini; the twilight, the antennae are fusifonv, " 
grow gradually thicker from ihe ba»e to the apex ; the winj* 
are horizontal or little inclined when the inwcl is at r«t; thf 
posienm wtn^ Vulvc l)nca bonvX icaxt^it« <uxaishcd with 



r«t ; thr ■ 
ilhangiA I 



ANNULOSA: INSECTA. 



2fi; 



W 

qMM ("mituculum") whkh u received into a hook od th« 
under mriiice oi the anU-rior wings ; and the [iuimc arc aever 




TTie NocturajJ Ltpidofta-a have the antennae seuecous, or 
■liiniiKihing araihully from (he base to the aftex, often serrated 
"fpcciinaiiM (fig. 9.1); the v.-ing5 in repose are horixontal or 
"•■nwd, and the hind- wings are furnished with a "retinaculum." 
** in the preceding section ; the pupn arc mostly smooth, 
""nciitnes spiny, and often enclosed in a cocoon. 

Oawji X, HvMEsoprERA. — Winga four, membranous, with 
"^ nervnrcs ; sometimes absent. Mouth always proiidcd 
*"h biiing')aws, or mandible* ; the maxilla: and labium often 
'wverted into a stictoHal organ. Femalex having the ex- 
J'<*'il)r of the abdomen mostly TuTnishcd with an ovipositor 
(***»« or aatkni). consisting chiefly of three clongaietl pro- 
^^^ of which two scn-c as a sheath for ihe third. Resides 
*[|* cenpound eyes, there arc usually three ocelli placed on 
"* lop of the head. The anlcnnx are generally filiform or 
'*'*«ous. The meUmor^>hoiiix is complete, but the various 
("'^i of iJw puj>a a/e vmb\c through ibc delicate tmioiwv^ 



268 



MANUAL OF ZOOLOGY. 



membrane. The larvse are sometimes provided with fee^ ud 
live on vegetable food (as in the TaUAredinida, fig. 95); but 
they are mostly footless, without a distinct head, and fed bj 
the adult. 

The Hymmoptera form a very extensive order, comprinng 
the Bees, Wasps, Ants, Ichneumons, Saw-fiies (fig. 95), ftc 





ne- 95— GoostberiT Saucily \Tinlkrrdi> i^stx!ariif\ \xm, pupi, aodiiuf*' 



The ovipositor, which is very generally present in the females 
of this order, is sometimes a boring organ {lerebra), or in othe 
cases a " sting" (aculcus). 

Amongst the Hymatoptera we find social communities, in 
many respects resembling those of the Termites, of which » 
description has already been given. The societies of BeO 
and Ants are well known, and merit a short description. 

The social Bees, of which the common Honey-bee [Afa 
mellifica) is so familiar an example, form organised communili«p 
consisting of three classes of individuals — the males, fematei 
and neuters. As a rule, each community consists of a angle 
female — " the queen" — and of the neuters, or " workers." Th 
impregnation of the female is effected by the production (^ 
males, or "drones," d\iniii^'ivt%\KMa«. ^^i impicgnatun 



ANNULOSA: INSECTA. 



369 



effected, ih« drones, as being tlien lucleu, are de* 
DjrctI by the workers. The ^gx produced by the fecnndiited 
queen are mosily intended to give origin to neuters, to which 
cod they arc placed in the ordinary ceils. The ova which are 
to give ofigio to females — the "queens" of future colonics — 
are placed in cells of a peculiar coiutmction, and the htvx 
are fed by the woriccra u-iih a special food. Tlie ova which 
are to jiroduce maleit are likewiite placed in cells, which are 
slightly l.irgvT than those allotted to the workcrx. It is as- 
serted, however, that this is not the sole or tnic cause of the 
production of the males ; but that the ova which arc intended 
to produce drones are not fertilised by the female with the 
•emcn which she has stored up in her spcrmatheca, and arc 
Ifaerefore produced by a process of Parthenogenesis. Thai 
the males are produced )janhenogenetically in some, at any 
rale, of the Hymtmptaxi, appears to have been placed beyond 
a reasonable doubt by the researches by Von Siebold.— (See 
Introduction.) 

In the Humlilc-becs (/IpmiiAt), and in the Wisps (yafiitfir), 
wc have societies essentially the same ns in the Honey-bee. 
In a large community of \V'as|iH, or " vespiary," there may be 
Kveral hundred fcnulos, of which few survi\-e the winter, and 
live to found fresh colonies next spring. The number of males 
is about equal to that of the females, but. unlike tlic <lrones of 
ibe Bees, the males work actively and defend the nc»t. As 
amongst the Bees, solitary species arc not uncommon. 

Tbe Ants (AvmMuAx) likewise form communities, consisting 
of males, females, and neuters (fig. 96). The males and 








females, as wc have seen in the case of the Termites, are 
winged, and are produced in great numbers at a partkulac 
paro d of the >>ear. They then quit the nesi aM \ia.u, aS^ei 




270 MAN-UAI. OF ZOOLOGY. 

which the males die. The females then lose their wingi ud 
fall to the ground, when they become the queens of fiesh 
societies. In some Ants, as in the Tetmites, the neuters ut 
divided into two classes — the workers and the soldiers — of 
which the former perform all the duties necessary for the pn- 
servation of the society except defending the nest, this bong 
left to the soldiers. In other cases, as many as three distinct 
orders or "castes" of neuters may be present in the same 
nest 

Amongst the more singular of the habits and instincts of 
Ants two may be mentioned — the instinct of making sUrei, 
and that of milking, so to speak, the little Plant-lice {AfAiJa). 
As regards the first of these, it is found that certain Ants pot- 
sess the extraordinary instinct of capturing the pupa: of OSaa 
species of Ants, and bringing them up as slaves. The rdi- 
tions between the master and the slaves vary a good deal in 
different species. In the case ni Formica rufesiens, for instancy 
the masters are entirely dependent u]x>n their slaves; the 
males and females do nothing except reproducing the species, 
and the neuters perform no other labour except that of captia- 
ing fresh slaves. The masters are in this case unable even to 
feed themselves, and their existence is maintained entirety b]r 
the devotion of the slaves. In Formica sanguinea, on tbe 
other hand, the number of slaves is much less, and both 
masters and slaves occupy themselves in performing most of 
the duties necessar>- for the community. The masters, ho*- 
ever, go atone when on slave-making expeditions ; and in cast 
of a migration, the masters carry the slaves in their mouths. 

A second singular fact in the history of Ants is found in the 
relations whicli subsist between them and the Aphides, « 
Plant-lice. The Aphides secrete, or rather excrete, a pecutiir 
viscid and sweet liquid, by means of a gland which is situated 
towards the extremity of the abdomen, and communicates with 
the exterior by two tubular filaments. Ants are extremely foud 
of this excretion, and it is a well-established fact that the 
Aphides allow themselves to be milked, as it were, by the Ants> 
For this purpose the Ant touches and caresses the abdomen 
of the Apliis with its antennie, whereupon the latter voluntarily 
exudes a drop of the coveted fluid. Ordinarily the Ants seek 
the Aphides upon plants ; but it is asserted that in some cases 
they keep Aphides, much in the same way as human beings 
keep cows — though this is probably partly imaginary. 

Ordkr XI. Stkepsiptlr.a. — Females without wings or feet, 
parasitic. Males possessing the posterior [wir of wings, which 
are large, merobianous, awA to\4«i \c(n%\Vi.4\va.ll^ like a fan. 



IT 

The anienor 



AXNUIXJSA : INSF.CTA. 



271 



ie anierior pair of vHngH rudir»cntai>', represented by a pair 
of singtibr twisted organ!). Jaw* abonivc. 

The S/rffii/>/fra con^stitule a wnatl OKIct, wliich JDctudtc 
certain [xirjMtcii of minute 
tixe. fouttd on Uccs and 
other Hymatoftera. The 
female is a noXx vermiforai 
pub, without feet, Inii with 
a homy head, which it |iro- 
trudct frofii twtween the 
abdominal segments of its 
host. The larvx arc active, 
and possess six feel ; vthilsl 
the males (lig, 97) arc 
winged, and lly about with 
great activity. 

OKDER XII. COLKOP- 

TCRA. — Motith nusltcnlory, furnished with an ujiptr lip or 
labrum, two mnt>dibles, two maxillA', with maxillary pnlpi 
(generally fnur-)otntc(l), and a movable lower lip or labium, 
witli two jointed labial pali>i. The four wing» are usually 
presenl, and tite anterior pair are not adapted for llight, but 
are hanjenmi by chitine, M as lo fomn i>rotectivc cases (elytra) 
fur the po«terior wiiij;« (6g. 9S). The inner nuugins of the 




Fie- »;.— Smpiipivn Sirtefi S/hkH, 




are ccnendly straight, and when in contact they form a 
loiuitiHlinal niiure. 'lite pOAterior wings ate membranous, 
anJ wlien not in u«e, are foldcvl transversely beneath the 
elytra. (Amongst dcvbiions U»m this state of parts may be 
mentioned the orxasiunal absence or rudimentary con<.litioi\ 
uf the hinder win^ rbc Boldeiin^ together o( the eV^Ui, i3nt 




878 



MANUAL OF ZOOLOGY. 



soft and yielding condition of the clyUu, or the absence 
bolh dylra anil wiiig»). The eyei are aiwaya cotapont, 
gmcrally circular, oval, or icnifonn, l>ut soincctnics cuupletdy 
divided. The unteniuc are extremely variable in fonn, gcDfr 
rally of eleven joints, somclimcs of fewer, rarely of twel 
11ie thorax is composed of a pio-mcso- and iDCta-lhorax, ' 
when the elytra arc closed, only the pro-thorax and a h\ 
plalc ("sailellum") belonging to tlic meso-thorax are visi 
The tamus it generally composed of live joints, sofnetimcs 
fewer, never more, and its last joint b usually furnished ''' 
two hooked claws. 








The larvre of Colnrf^tra arc generally composed of ihime 
sepnent.s, including the head. 'ITic body is generally soft «* 
flcNliy. the head homy, and the mouth adapted for mosiicilica 
Tlx; antcnnic arc small, usually of three or four joinis, «tl^ 
ocelli at their base. They have tliree pairs of legs altachtd » 
the thorax, and sometimes anal i>ro-I<^ or fleshy tiiberde 
The pujtia is sometimes eDclose<l in a cocoon, and the [aR> 
of the perfect insect are always distiiictly recognisable in lb 
pupa. 

^'he order Cclmptera includes all those insects comnoatf 
known at "Beetles," and comprises an enormous numbav 
genera and sikcics. They arc remarkable, a^ a general r* 
for their hatd polished integument, their gliiicrii)^ oAea a^ 
coloura, and tlicir voradous habits. They ore giwp*^ 



tallic 



by LatrctUc \\\ Xlie fu\\o<N\1^^twu MOasm&> 




[. Poaamtra. — ^Tarsus five-jointed, 
t. Htl<r0mtra.~^xn\x% of vno anterior pain <A l«gt fiv«- 
Ued, of the posterior pair four-jointed. 
\. Teframtra. — ^Tarsus four-jointed. 
y. Trimera. — Tarsus thrcc-joinlcd, 

DiSTRiBtn'ioN OF Insecta IX Time. — The earliest koovn 
ects have been discovered in the Devonian Rocks of 
unca, and coiuitt of the remains of Neur^ptera." Others, 
might have been anticijxiteit, have been found in the Coal- 
•sures. In the Secondary Kock.s rem.iinK of in.sectx have 
en found abundantly in certain beds of the Oohtic and l.iassic 
nutions. [n some Tcniaiy strata Ltfideftera and other in- 
3s have been fouD<l in a good slate of preservation. Amber, 
Itch is a Ibisil resin, has ton^; been known to coDUin many 
iccts in its interior (in certain specimens) ; and all of these 
pear to belong to extinct siiecies, though amber, geologically 
eaking, is not an ancient product. 

* The Devonian Xantfttr* of North America are moit dowlr allied to 
iEfAoHoidt; bat one form U in nmny tctpecU lnin»lllniia1 belwecB 
tordcn Ortkfplira and Ntutvfttta. intccin btloncinf; lo the Nrttrrp- 
■ Irii., Mi»mm and tfrmtriitia'i, (o the Oiiktflfra i^lMima), and lu the 

Mm (fi^pnm), have also been described 6ain lh« Citbooifervia 

I of Nonh America. 



274 



MOLL use A. 



CHAPTER XLI. 

SUB.KINGDOM MOLLUSCA. 

Sub-kingdom Moli^usca. — The Moltusat may be defined u in- 
cluding sofc-bodled animals, which are usuaJly provided with m 
exoskeleton. The intestinal canal is bounded by its own pnpa 
walls, and is completely shut off from the perivisceral cariQ. 
The alimentary canal is situated between ihe haemal sydcs^ 
which lies dorsally, and the neural system, which is situated 
towards the ventral aspect of the body. The nervous systtn 

(hg. too) in its highest it- 
vclopmcnt consists of thi« 
principal ganglia, which m 
reduced to one in the knnr 
forms. Usually there ii > 
distinct propulsi^'e otpt 
by which the circulatioD ii 
carried on, but this is w- 
casionally absent Distinct 
respiratory organs may « 
may not be present St 
production is sexual, thoo^ 
gemmation is also oca- 
sionaljy superadded. The higher Mollusca are all simple uu- 
mats, but many of the lower forms are capable of foimiiil 
colonies by continuous gemmation. 

The digestive system in all the Mollusca consists ofa nioiill^ 
gullet, stomach, intestine, and anus — though in some of ibe 
Brachiopoda, and in a few other forms, the intestine aifc 
caecally. In some the mouth is surrounded by ciliated tes- 
tacies {Polyioa, fig. 102); in others it is furnished with m 
ciliated arms {BmMppoda, fig. 105) ; in the bivalves (iMidt 
branMata) it is mostly furnished with four membranous pro- 
cesses or palpi (tig. io()) ; in others it is provided with a com- 
plicated appaialus ot Xetfti t^Gosterotorfo, tig, 108, and Plin- 




Fie- loa — Diammof 9 Moltinc aALiiDcn- 
Lary oral ; k Heajl ; _/" Fool ; h Cerebri 



iplanchnic fangLoD. 



PuictD- 



MOLLCSCA: CENKRAI, CHARACTERS. 



vs 



and, lastly, the Ct^akpoda have, in addition, hom^ or 
ecus nundiMes, forming a kind of beak. \\'ell-dcvcIopc(l 
!jr gtnnds arc usually prcstnt; the liver in the higher 
u of large size, and pours its secretion either into the 
eh or into tlic coinme»cemeni of the inleHtine ; und a 
organ has been detected in mott of the Moi/nsca proper. 
I is no distinct absoibcnt sytlcm, but the products of 
ion pcm bjr exosmosc into tJic general nbdoniinal cjivily, 
)eDce into the brgcr veins, which arc sometimes pierced 
^CTOiis Toiind holes for this purpose. 
I blood is colourless, or nearly so. In the Palytoa the 
ttion is carried on by ciliarj- action, and there is no db- 
propulsive organ, or deiinite coune of the circulating 
• Id the DtnUatts the heart ix a simple tube, open at both 
pnd the cmiree of the cireulation i.s periodically revered. 
k Braehioftada the coutm of the circulation is not defi- 
:efiainc<), and it is doubtful if a true heart is present 
In the higher MoUtuea a distinct heart is always 
and consists of an auricle which receives the acraicd 
front the bTealhingK>r^n, and a muscular ventricle 
ifiels it llirovgh the ^yjiteniic ves.sels. I'hat a syntem 
lUriet in many cases intervene* Iwtween the arteries 
appeart from recent researches to be probable. 
casei the bean of the McUusca is systemic, distributing 
blood to the body, and in no case is il rcspiraloty, 
ping the non-aerated blood to the brcaihing^jtgan. 
khe Ffflywa there is no differentiated respirator)- organ, 
pe function of respiration is discharged mainly by the 
^Dwn of ciliated tentacles. In the TunitaUx respiration 
ICted l>y means of the pharynj^eal or bninchial sac ; and 
b BriiihiofK<da by the oral arms, and p(»»ilily, to some 
Lbyan "atrial" or "irater-vaficular" iptcm. furnished 
IDotTactilc dilatations. In the higher Molluscs a distinct 
Ung-organ is always present, a portion of the mantle being 
KSed for Ibis purpose. In the Lamellibranchiata, and 
ichiate Goilmfoda, the breathing-organs are in the 
lamellar and pectinate giUs ; and the same is tlie case 
CffMaief^a. In the pulmonate Gastercfioda, in 
respiration U aerial, a pulmonary sac or air-cbaniber is 
d by the folding of a jwrtion of the mantle, over the 
of which the puhnonary vessels are distributed. The 
r thus formed communicates with ihe exterior by a 
t ajkCTIure which can be opened or closed at will ; anil the 
•iKin of the effete air within the sac appcais to be cffecwA 
or entire)/ by ample diffusion. 



2/6 MANUAL OF ZOOLOGY. 

The nervous system vaiies considerably in its devetopracnL 
In the Poiysoa, TunUata, and Brathhpoda — which colIectiTeljr 
constitute the Molluscoida — the nervous system consists of a 
single ganglion, or of a principal pair with accessoiy fpui^ia. 
placed between the oral and anal apertures, or on the vailnl 
surface of the body. The true Molluscan ^pe (fig. loo), ha«^ 
ever, of nervous system is constituted by the presence oTduce 
pairs of ganglia, connected with one another by cammissuits, 
but distributed in a characteristically scattered manner (hetoo- 
gangliate type). One of these ganglia is situated above the 
oesophagus, and is called the " supra-cesophageal" or "cerebral" 
ganglion. A second is placed below the oesophagus, and ii 
termed the " infra-aesophageal " or "pedal" gangUon (from b 
supplying the nerves to the "foot"). The third pair is tfc« 
most persistent, and is tenned the "branchial" or "parid» 
splanchnic " ganglion. 

Organs of sight exist in some of the lower, and in the maj* 
rity of the higher, MeUmca. In the Cephalopoda, and in some 
of the Gasteropoda (e.g. Sirombida), the eyes are of a very high 
type of organisation. In the Lamettibraruhiata the adults iR 
either destitute of organs of vision, or possess numerous simplt 
eyes (" ocelli") placed along the margins of the mantle-lobci 
Similar ocelli are also found in some of the TunUala, placed 
between the oral tentacles. Organs of hearing exist in the 
more highly organised MoUusca, especially in the Gastenfiia 
and Cephalopoda, and supposed olfactory organs occur in stane 
of the latter. 

Reproduction amongst the MoUusca is almost invarialijy 
sexual, but it is by continuous gemmation that the colonies oT 
the Poiysoa, and the social and compound Tiaricata, are pro- 
duced, and the " statoblasts " of the former offer a good ei- 
arople of non-sexual reproducrion. The sexes are usually dis- 
tinct, but are in many cases united in the same individual In 
many fonns the ova are arranged in rows, so as to form a strap 
or ribbon-shaped structure, termed the "nidamental ribbon." 

As implied by their scientihc name, the Mollusm are mostlf 
soft-bodied animals; but their popular name of "Shell-fish"' 
expresses the fact, that the presence of a shell, protecting the 
soft body, is likewise a very characteristic feature in the sob- 
kingdom. At the same time, a shell is not universally present, 
and many of the MoUusca are either permanently naked, ot 
possess nothing that would be ordinarily looked upon as a 
shell. \\'hen there is either no shell at all, or merely a nidi- 
mentary shell enclosed in the mantle, the Mollusc is said to be 
"naked." The shcW ot \h« "\cs>aRjw»»" MoUusca is veij 




mollusca: general characters. 

ly related to the r»pimtor>- organs ; " inilecd it may be 
g;uded u tpneumaskt/^ifi, being nsentioliy x calcified por- 
Ht of the mantle, of which the brmthing-ora::iii i* at most a 
ecioJiscd jNkrl. ... In its most reduced form the shell 
only A hoJlow cone or p1aic, prolccting the brent liing-orcan 
d hcifl, as in Limax, Teitacelh, and Ciririttria. Its peculiar 
Iturcs always relate to the condition of the breathing-organ, 
d ta Ttrtbtatula and Pdenaia it becomes identified with the 
1 In the Nudibriuuht the vascular mantle jiurfonnK, wholly 
JA part, the re«]>irator}- office. In the Ctphahp&dt the »bell 
■nes complioied by the addition of a distinct. Internal, 
ntbered portion (p/iragmiUeiK). which is property a visteral 
ehrton." — {WoodwRTd.) In a great many of the M^lutea 
oper the shell consists of but a single piece, and thcv' ate 
Ikd "univalves." In many others the shell consists of two 
puaie phles or " valve*," and these are called "bivalves," 
I others, again, as in the Chitcn, the shell consists of more 
tn two i>ie(:es, and Is said 10 be "multivalve." Moit, bow- 
er, of ihc multivalve shells of older writers are in reality 
feruble to the Cirriprdia, 

All Ihe testaceous Mollusca (except the Argonaut), and 
ast of the " naked " fonns, acquire a rudimentary shell before 
eir liberation from the ovum. In (he latter this rudimentsry 
eU is cast off as the embryo grows, but in the former it he- 
mes the "nucleus" of the aduti shell. In Ihe bivalves the 
ibminic dtell or "nucleus" is situated at the beak or 
iinuo " of each valve, and is oAcn very imlike the remainder 
the shell 

In compodlion tlie shell of the MeUmta consists of carbon- 
; of lime — usually havinK the atomic arrangement of calciic 
«tth a small propo«tion of animal matter. In the Phola- 
itt, however, the calcareous matter exisli in the atlitirtipic 
ndilion of anagonile, which ts very much hanlcr than otrilc. 
\ regards their texture, three principal varieties of shells may 
fctstinpiishcd— viz.. the *' porccltanous. ' the "nacreous," 
B|h« "fibrous," In the "nacreous" or pearly' shells, as seen 
^bnother-of-pcarl," the shell has a peculiar lustre, due to 
Pbinute undulations of the edges of alternate layers of car- 
nate of lime and membrane. The "hbrous" shells are 
mposed of sneressive layers of prismatic cells. Tlie "por- 
ItaAOtui " shell has a more complicated stnictiire, and i.i eom- 
ised of three layers or strata, each of which is made up of 
ly numerous plates, "like cards placed on edge." 'llie di- 
:tioa m which these vcitical plates arc placed, is sometimes 
ouverse Ln the nvalxai Itycr, and lengthwise in v\\t vtCQ 



i 




279 



MANUAL OF ZOOLOGY. 



Dtbere ; or loagimdiiul in the mi<<HU^ and tnnsvcne in the 
oater and inner sno. 

All lii-ing shells hare an ootcr layer of animal matta, which 
is knovn as the " epidennis," or " periostracum." This ii 
sometimes of extreme lenuitj-, but is sometimes veiy thick, tbe 
latter being espvcially the case with those shells which m 
found in iiesh waier. 

In manv of the spiral univalves, as the animal growi it 
withdraws itself from the upper poTti<Hi of the shell, often pn- 
titioning off the space thus left vacant In many instances 
the portion thus abandoned (alls oS, and the shell becomei 
" truncated," or *' decollated ;" this being the nonnal cooditiaD 
in fully-grown examples of some shells. 

In the great majorit)- of uni\-alves tbe shell is coiled inU 
a spiial, the direction of which is right-handed, but in some 
cases the spiral is left-handed, and the shell is said to be "n- 
versed," or "sinistral." The reveised shell may occur ai dt 
nonnal condition of the species, or it may occur simply u a 
variety of a form which is normally right-handed, or " dudnL* 

The sub-kingdom Mollusca is divided into two great drri- 
sions, tenned respectively the MeUutmda, and the MoBuu' 
proper. In the former of these the nervous system consists of 
a single ganglion or principal pair of ganglia, and there ii 
either no circulatory organ or an imperfect heart In the 
latter the nervous system consists of three principal pain of 
ganglia, and there is a well-developed heart, consisdng oTH 
least two chambers. 




MOLL USCOIDA. 



CHAPTER XLir. 
POLVZOA, 



DM A. MoLLUSCOtDA. — Nmmu system omtMiig ^ a 
Vnglion, ffr 0/ a frineifai fair wilA attasory gtwpia ; no 
«*^an o/t/ie eim/atian, or an imferfat htari. 
I dirision includes three classes — >iz., the Polytoa^ the 
te, and the BnuhiopoHa. 

I. POLYZOA {Bryoted). — The members of this class 
u follows: — "AlimenLu^- cunul (usji ended in a 
walled sac, from which it may be panially protruded 
«ss of cvagination, and into which it may be again 
by iDVB^nation. Mouth surrounded by a circle or 
It of hollow, ciliated tentacles; animals always ronmng 
(ite colonies." — (Allmaii.) 

the P^ytoa live in an associaled form in colonies or 

tuiju." which are sometimes foliaeeoux (tig. 101, i},soi»&- 

tranchcii and plant-like, sometimes encrusting, and very 

|are free. Each " poly/oaritim " consists of on assem- 

Bf distinct but similar 70oids arising by continuous gcm- 

\ from a single primordial individual. The colonics thus 

pcd arc in very many respects closely similar to those of 

tof the Hydroid Poi)'pes, with which, indeed, tlie Poiytt^ 

ir a long time classed. The " poly/oarium," however, 

i^«mAi dijfen from the polypidom of a composite Hy- 

I the /KMm/ fact that the separate cells of the former 

connminkate with one another otherwise than by the 

rity of the external integument ; whereas the zooids of 

[er are united by an organic connecting medium, or 

from which they take their origin. On this 

Ilusk observes: — 

has been before said that tlic Pulytoa arc always asso- 

into compound growtKi, m:ule up of a cx>ngeries of in* 

which, xho\jg)\ distinct, yet retain some de^« (A 



380 



MANUAL OP ZOOLOGY. 



intercom man ic3tion, comparable in kind pcrhjips, 
in degree, to what obiains in many of the compound 
ann. That this comniunitir exists is proved by the 
inexpli<'itl)le circumstance tliat the polyioaria in many in 
present elements common to the whole growth, and not ht■^ 
longing specially to any individual. The chief borvd of ceo- 
ncction would appear to rcsi<le partly in the continiiit}- ni tk 
external integument, and partly also, in all probabililj', in 1 1 
slow interchange of the vital fluid with which the cavttiet ti\ 
the cclb are charged." 

In one suborder of the P^yua {Otwttemata), the polfto-l 
ariiun consists of a scries of cells arising from a conimoo tub^J 
but thi» exception does not affect the value of the 
gtntrat distinction between the Polywa and the Uydnids. 

A second point of ditTerence ts found in the intinAblv txn-^ 
ncous (or chitinoiis) texture of the paIy|tidoms of the NyJnH'. 
whereas those of the Polytoa may be corneous or fleshy, hn 
arc in tlic majority of instances more or less highly charged viA 
carbonate of lime. 

The homomorpKism, however, which subsists between tbe 
Pdjtca and the /fydroula is sho»Ti most decitively not to be 
a tnic affinity, when the struct^irc of the indindua) aooidi ii 
examined. The polypitc of a Hydroid Zooi)hy1e, as we hot 
already seen, possesses no alimcntar>- canal distinct from the 
general cavity of the body ; there are no traces of a imtka 
system, and the reproductive organs are in the form of exto- 
na) processes of the body-wall. In tlie zooidof all the JVpt* 
(fig. loi, 3), on tlie other hand, there is a distinct Alimenttff 
canal, comjiletely shut off from the KORiaiic cavity ; a nemu 
system is present, and the reproductive organs arc contiined 
within the body. 

The following arc the more important differences in the to- 
minology employed to designate the various pdtrta of tbe ce» 
pound growths of the Po/jwa and the IfydrMCa. In the 
Hydroida the entire colony is called the " hydrosoma." and lu 
investing layer, when present, is called ilie "polvjary," a 
"polypidom;" whilst the individuals c^ompoaing the hydtoMM 
are odled the the " polypiics," and the cups in which tbe«) 
in some cases contained are called " hydroihcca:." In 
Pclyxcit the entire colony — or its entire dermal system— ■< 
called the "' [loly/oarium " or " cocnccdum ; " the 
looids are called "polypides;" and the little chambers in *li 
each is contained are called the " cells.' 

It will be seen, thcrcfoie, tJut the leimjvtjfif* is 
to the Euoid of a compound Hydr«sefyi, or to the entire I 





molluscoida: polvzoa. 



38c 



soma of a simple member of the cbss. The term jta^ia 
applied to a simple AdiwsMn, or to the 20di<ls of a compound 
actinosoma. Lastly, the term polypiSe is excluuvcl)' em]>loyed 
to designate the zooid of one of the Pfilytoa. 

The constiuctioB of a \y\i\csl polypitle of a Polyscen b thus 
described by Professor Aluiiai) {fig. loi, i) : — 

" Let as imagine an alimentary canal, consisting of oeso- 
phagus, aUMnach, and intestine, to be furnished nt iis origin 
with long dtiatcd tentacula, and to have a single ncivous gan- 
glion placed upon one side of the ocsopliagus. Lei ui iiovr 
sappo«e this canal to be bent back upon itsulf towanU the 
«iae of the ganglion, so as to approximate the tenninniion to 
the origin. Let us further imagine the digestive tube thus 
constiiiited to be suspended in a fluiil contained in a mem- 
branous sac with two openings, one for (he moulh and the 
other for the vent, the tentscula alone being exiem.il to (he 
nc Let us slil) further suppose the alimentary tube, by means 
ol a system of muscles, to admit of being retraaed or pro- 
truded according to the will of the animal; the retraction 
being accompanied by an invagination of the sac, so as psr- 
tially or entirety to include the otal (cnta^rles within it; and if 
to these characters vre add the ]>rcsence of true sexual organs 
in the form of ovary and testis, occupying some ponion of tlie 
interior of the sac, and the negative chaiactcr of the absence 
of all vestige of a heart, we shall have, perhaps, as correct 
an idea — apart from aU considerations of homology or deriva- 
Utm from an archetype — as can be conveyed of the cwcntial 
structure of a Pfljwcn in its simplest and most generalised 
condition. 

"To give, howei-er, more actuality to our ideal Pi}i]izeiSH, 
we may bear in mind that the immediately investing sac has 
the power, in almost every case, of secreting from its exiemnl 
soT^e a secondary investment of ver}- various constitution 
m the difTerent groups ; and we may, moreover, conceive of 
the entire animal with its digestive lube, tenUcula. ganglion, 
muKlrs, generative organs, cimimambient fluid, and investing 
aev repealing itself by gemmation, and thus producing one 
or more iwccisely similar systems, holding a definite position 
relatively to one another, while all continue organically united, 
uid we shall then have the actual condition presented hy the 
Psfytoa in iheir fully ^leveloped state." 

The vast majority of the P^ytsa are fixed, but this is not 
universally the case. Thus the singular freshwater Cristatt/ia 
H free and locomulive, creeping about hy means of a Hattcncd 
base, not unlike the loot of the Gaslervfoda. 



^dJKiDid base, i 



282 



>tANUAL OF ZOOLOGY. 



The wo fuiulamfnul streclurcs of the "coeracium' of 1 
/^f/ysfiin — VIZ., Ihc immediately in\-cstiiig sac, and its seeoo- 
dary investment, arc Bomctirocs tcnncd the " endoderai " aod 






/ ..' 



^t«^— Mn^ilr^ynf IVIvrox i- pDrtion at ihc a m p cMin rff Jutiw tnmtttt^ 
.■CnkAcil, 1 UiiKiini if • I*n1]rKiAn <«/Mf AIIiud); ' Kii^ii of iha aaiA 
nimuiided 1^ tenucki: I Alineeury can^; r Ama; ^ NinraiH uDckHi f 
laTticina UE (KiocpiJ ; /TeUH : /* Oniy: gttttaaoc niud*. |. Biihtal 

"ectoderm;" but u these terms are employed in describing tbt 
Hydrvsoa, it is better to make use of tlic lerm* "cndocyK* 
and " ectocyst," proposed by Dr Allman. 

The "ectocyst," or cxtcnml invc*tm<rnt of the coinoeeiun 
is usually a brown, pcrgsmcntnccous. probably chitinoos, but 
often highly calcareous, membr.inc ; and it is by the eciocr* 
that Ihc "cells" arc fonncd. In Criitaitlh, alone of tk 
PofytM, there is no cctoc>'st, and in Lepk»pui (fig. loj, 3) ifc* 
ectocyst is geUlioouB in its consistence. In many caies Ibt 
ectocyst is provided with singular appendaj^es, supposed to be 
weapons of olTence and defence, termed "avicularia" (fi^ 101. 
3) and "vibracula." The avicularia, or "bird's-head procesMSi' 
differ a good iIcjU in shape, but consist csscniiaity xA ** 
movable mnndible and a cup liimishcd mih a homy Iwik 
with which the point of Ihc mandible is capable ^ bcns 
brought into apposition." — (Busk.) In shape the avicnlin 
often closely resemble the head of a bird, an<l tliey are in BWir 
respects comparable with the " pedicellari^e " of itie EcktMJf- 
mala* In the " vibracula," the place of tlic nunilible of tbe 
* There ii groM rmon, however, as itown by llaxl«y, to Kgiri '*• 




MOLLUSCOIDA: POLVZOA. 



aSj 



anculariiiin is talwD bf a bristle, or setA, which is capable of 
extensive movement. 

The endocyst is always soft. coDiraciile, and meinbranoits. 
It lines the inlerior of tlie cclli formed by the ectocyst, and is 
retlerted buckwaidx at the mouth of the cell, so as to be itiva- 
giiuUcd, or inverted into itself; and it finally tetminatcs by 
being attached to the base of the circlet of tentacles. Tbis 
invagination o( the cndocyst is laorc or less permnnenlly pre- 
sent in all the fresh-water Polytsa, A portion of the inner 
surface of the endocyst, if not the whole, is furnished with 
Ttbnitile cilia. 




PW. >M —I. ^n^mcM <I Flititm rrwiMM, one «f OkSutoiui. nllimluit s A 
■■■I* piilnadc tt VtOtrm. niuttilfiKl, Jwwinc (h* trUcular <mrH lA m»ImI« 
^ * WtTW •' l-f^ t" trytuOiam. ■ fntli-niH Pa])ri*«a, UcUr mniM, 
^■■iMat UK >«■■ ifcii liMpBi avm v! miKlci: ' Tealscalu ennni : tCuUtii 
raumttb: dltuaift; iJum; eCmari: i Kaiocfi; < Eoacyu : / Fodcidiu. 

The month oT each polypide is surrounded by a crown of 
tubular, non -re tractile tentacles, which have their sides ciliated, 
and are arranged sometimes in a circle and sometimes in a 
oesccnL In the fiesh-watcr /i'/vwa the tentacles are united 
towards their bases by a funnel-shaped nftcmbrane, known ai 
the " calyx. ' The tentacles are borne u]>on a kind of disc, or 

NnlrMllfrM, iic| at mct* apptDdoga or ortai» or any kicd, but m peciiliirly' 
■milUpl ittiJi, hiving many iiiif^ulai poinii of aKniUj u-jth Ihc SrarAit- 
/■At. Th« jn-ifiilaria, tike ihc /vJUilIariit o( the I'^tiiiKdirmala, Mntlmie 
IkdMMV^naiti lone after the dcalh ci (he uiimal. 




384 



MANUAL OF ZOOLOCV. 




stage, which is termed by ProfeGsor Allman th« " lophophore.' 
In the majoril)- Qf PoJyvMi — including alnuMt all the rnanM 
species — the lophophorc is circular (fig. loa. »); but in tnostoT 
the frcih-waicr forms it has its neural side extended tnio two 
long aims, so (hat the entire lophophorc becomes crescentic 
or " honte-shoe-ihaped " (fif[. loi, 3); hence this seaioo is 
sometimes collectively termed the " Htppocrei«an *' fitl^ut. 
In all the P^yxa in which this crescentic coiulition ai the 
lophophorc exists, there is also a singular valve-like oipa 
which arches over the mouth, and is termed the " eptstooK.* 
The only marine forms in which the lophophorc is bilsiotl 
arc PedialliDi and RhahilopleHra ; the only fresh-water speoct 
in which the lopliophore is orbicular are PaluJUdtA i&4 
Urnatdla. 

The mouth conducts by an (c.tophagut into a dilated stomacK 
In some cases a [ihaiynx mny be present, and in others thi 
is in front of the stomach .1 muscular proven triculus, or 
zard. From the stomach proceeds the intestine, which 
turns fom-ard to open by a distinct anus close lo the mouth.' 
As the ncn'ous ganglion is situated on tlial side of the mouth 
towards which the intestine turns in order to reach its tennina- 
tion, the intestine is said to have a "neural flexure," and thi> 
relation is constant throughout the entirc class. 

Respiration in the /**>»« appears to be carried on by tbe 
ciliated tentacles, and by the " perigastric space," whidi it 
filled with a clear fluid, containing solid paiticjes in siupe»4 
sion. A kind of circulation is ke^rt up in this " purigatfiic 
fluid" by means of the cilia lining the inner stitfare of lie 
endocyit. Beyond this there is nothing that cotild b« called 
a circulation, and thcrc are no distinct circulatory ofgaas cf 
any kind. 

The nervous system in all the PelysM consists of a singk 
small ganglion (%. >ot. 1), placed upon one side of the Ofo- 
phagus, between it and the anal aperture. Betides the sit^ 
^glion which belongs to each polypide, there is also in nmf, 
if not in all, of the Pt^yztia, a " colonial nen'ous s>'stem ; * llii 
is to say, there is a well-ilcvdoped nervous sj-stcm. whici 
unites together the various looids composing the colony, vA 
brings them into relation with one another. It is probably a 
virtue of this system that the atikularia are enabled to cM- 
liniie their movements, and retain their irritabiliiy after 4* 
death of the polypides. 

The muscular system is well dei'cloped, and cnnHUt (' 
various muscular hands, with stiectal functions attacliinK U 
each. I'hc most important fasciculi arc the reuactof muicia 




uolluscoida: tom-zoa. 



385 



L 



(lig. loi, 3, gV which retract ihc upper portion of the polypide 
within the cell. These muscles arise from the inner surface of 
the cndocyst near Ujc bottom of the cell, and arc inscned into 
the iip[KT part of the cesopbsgus. The pol)pidc whun re- 
tracted, is ^ain exserted, chiefly by the action of the " jjuricial 
musdch," which are in the form ot circular bundles running 
Uanavenely round the cell. 

As far w u known, all the /Wytai are hcnruiphroditc, ench 
polypide containing an ovary and testis (fig. loi, i). The 
ovary is situated near the summit of the cell, and is attached 
to the inner surface of the endocyst. The testis is situated at 
the bottom of tlic cell, and a curious cjlindrica! appendage, 
called the "ftmiculua," usually passes fioni it to the fundus of 
the stomach. There are no Cerent ducts to the reproductive 
organs ; and tlie nnxlucts of generation — i.f., (he spermatoroa 
aad ova — arc disdiaigcd into the |>crigaslnc space, where 
fecundation takes place; but it is not cenainly known how 
the inprt^nated ova escape into the exicmal medium. 

As already mentioned, continuous gemmation occurs in all 
tbc /V/ffM, the fresh xooids thus produced remaining attached 
to the organism Iroin which they were budded forth, and thus 
giving rue to a com|>oun<l growth. 

A fom of discunttnuous gcmin.-ilion, however, occurs in 
many of the P^ytva, in which ccruin singular bodies, called 
" statoblasts," are developed in the interior of the polypide. 
The staloUasts arc found in certain seasons lying loose in the 
pcngastric cavity. In form "they may be generally described 
u lenticular bodies, varying, according to the speaes, from an 
orbicular to an elongated-oval figure, and enclosed in a horny 
shell, which consists of two concavo-convex di.tcs \inited by 
their margins, where they arc further *lrcngthcned by a ring 
which run.s round the entire margin, and is of different sinic- 
turc from the discs. . . . When the statoblasts arc placed 
under circumstances favouring their development, ihey open 
by the separation from one another of the two faces, and 
there then escapes from them a young PafyuM, already in an 
advanced stage of development, and in all essential respecu 
rcMmbUng the adult tnditidual in whose cell the statoblasis 
were proauced." — (Alhnan.) The sutoblaxu arc formed us 
buii* u]K>n the " funiculus "—the cord already alluded to as 
extending from the testis to the stomach — upon whi<:h they 
may usually be seen in ditTcrcnt st.igcs of grow-th. They do 
not appear to be set free from the perigastric space prior to 
the death of tlic adult, and when liberated they are enabled 
lo Soat near the surface of the water, in consequence of the 




286 MANUAL OF ZOOLOGY. 

cells of the marginal ring, or "annulus," being spongy ind 
filled with air. They must be looked upon as "gtmrnt! pecu- 
liarly encysted, and destined to remain for a period in t qm- 
escent or pupa-like state." — (Allman.) 

As regards the development of the Pefytoa, the embryo 
upon its emergence from the ovum presents itself &s a ciliated, 
free-swimming, sac-like body, from which the polypide is sub- 
sequently produced by a process of gemmation. In the sin- 
gular Hhabdopleura the primitive bud is enclosed between two 
fleshy lobes or valve-like plates, attached along their doisl 
margin, and giving exit in front to the rudimentary lophophrat. 
As the development proceeds, these plates cease to keep paw 
in their growth with the rest of the bud ; till ultimately thef 
appear as a peculiar shield-like organ on the ha:mal side of the 
lophophore. These lobes have been compared by Dr Allmin 
with Uie mantle-lobes of the Lamdlibranchtaia, 

Divisions of the Polvzoa. — The Pelysoa are divided inw 
two divisions or orders — the Phylactolamata {fig. loa, 3), dii- 
tinguished by the possession of a bilateral hoise-shoe^i^icil 
lophophore, and of an "epistome" arching over the moudi; 
and the Gymnoiamaia (fig. los, i), in which the lophophore is 
orbicular, and there is no epistome. 

Table of the Divisions op the Polvzoa. 

Order I. Phylactol-bmata. 

Lophop^o^e bilateral ; mouth with an epiGtome. 
Sub-ordfT I. Lefihopca (fresh -water). 

Arms of lopbophotc free or ob«ol«le ; consistence homy, ioU<il- 
careous. 
Sa&'order 2. Pedktllinea (marine}. 

Arms of lophophore united at their extremities ; conustenceicA. 
fleshy. 
Sui-crder 2' ^^oMJ/Zn/rea (marine). 

C(en<ecLum branched, adherent, membranous, with s solid wti- 
nous rod on its adherent side, to which the polypites are attado' 
by their'funtciili. Lophophore completely hippocrepian, will » j 
peculiar shield-like body on its hxmal side. No epistome (?) 

OanER II. GVMNOI-«MATA. j 

Lophophore orbicular, or nearly so ; no epistome. 
Sub-ordrr 4. Paludiidlca (fresh -water). 

Polypide completely relnclile ; evagination of Icntaculnr dxW* 
imperfect ; consistence horny ur sub- calcareous. 
Sub-ora/r 5. Chtiloslomala (marine). 

Polypide completely retractile; evaglnalion perfect ; orifice of m 
sub-terminal, of less diameter than the cell, and usually closed "nj 
a movable iip 01 shutter, sometimes by a contractile sphincter! m* 
nottubulu', tonsi«i«icc wk*iw«i,V.OTTC5,t«fleriiY. 



holluscoida: tunicata. 



387 



. . - 6, Ovfrrikitiii (marine). 

C«ll tuuiluf ; uiliM lermlnol, aT ihe Hunc dunwtcr as llie cell) 
irilfcoiM uiy uoiMble ■ppajaliu C>r ilx ctouurc ; can&utcnoc cnl- 

. JhtunAr 7. OtmtltmMa (in*riiic). 

0«WM of lh« ocll Icrminal, (umiihcd »itb A usualljr Ktoto frilii^ 
for Jin dOMre : oclli duiincl, aming from « voounon tubi ; CMuUt* 
tcnce bontj or cuianc 




CHAPTER XLIU. 

BS II. Tvf ICATA {AtdJwufa). — 'Hie members of this class 
of the MoUuiarida arc dcHned as Totlovs : — " Alimentary ninal 

Kispi.-ndctl in « double-woUed sac, but Dot capable or protni- 
Dn and tciraction ; mouth o|}eniiiK inio the botioiQ of a ic- 
spiratory Siac, w)i<mc u.ilh jrc inuro or Wss coiiii>letcl)' lined by 
a netwoik of blood-vessels" — (Allmnn.) Animal limple or 
coaipo«ilc. An imperfect hcan in the form of a simple tube 
open at both ends. 

The Tunicaries arc all marine, and arc protected by a Ica- 
Uioy, elastic ini^umeiit, which takes the place of a shell. In 
appeaiaDcc a solitary Ascidiaii (Ag. 103) may be compared to 
• double -necked jar with two prominent apertures situated 
dose to one another at the free cxtrcmily oJ the animal, one 
of ihcxe being the mouth, whilst the other serves ax an excrc- 
XoTj a|>eTture. The covering of an Ascidian is composed of 
two layere. Of these the outer is called the " external tunic,'* 
or " test," and is dist ingulf lied by its coriaceous or cartilaginous 
coosistence. It is also lemarkable for containing a aubstancc 
which pves the same chemi<:nl reactions as cellulose, and is 
probably identical with this cturact eristic vegetable product. 
^Cbueit is lined by a lecondeuat, which ix termed the "second 
^^^^r or "fDanllc," and which is mainly composed of longi- 
^VHU and ciraiLair muscular fibres. Uy means of these the 
aoinial >s endowed with great conttaciility, and has the power 
of ejecting water from its branchial aperture with considerable 
force. TIte mantle lines tlie test, but is only slightly ami 
loosely attachett 10 it, e>pecially near the apenures. The 
RKMttbtSgenerallysurTOTinded by a circlet ofsniall, non-ciltatcd, 
non-relraciile tentacles, and opens into a large chamber (fi^ 
>oif >i ^)' which unM]l>' occupies the greater \tm of t!l\c ca.v'vv'^ 




288 



MANUAL OF ZOOLOGV. 



of th« mantle, and bas il5 walls pctrorated by numerous tfC- 
tUTcs. This is known variously as th« " i>l»iir^n)i," ihe "fci|i- 
ratoryaac," or the "branchial sac" (It mii^t t>e letncmbotil 
that the apenure here spoken of as (he mouth can ooljr be 
looked ujxtn in tliis lixht jiruvidcd th.tt the respiratory ec a 
looked ujwD as the pharynx, liy Prornsor Allman, whoK 
ddtnilion is given at the head of this chapter, tills view it mi 
accepted, and consequently the internal or in/oior opening*' 
the respiratory sac is regarded as the true month.) Inreriorif 
the res|>iraiory sac leads by a second ajtcrturc into an a» 
pha^s, which opens into a capadotu stomach. From Ac 





•pcnuni AAtiwl ■pHtunj < PhanncwTut tniKhiil ft, irilh in > 
■puiuM, J AliniBlary caiiil. MtKlnhMul B*«r< -. t Ahb; / Air 
vow gucllm. %, Cr^AtnttfiOitt^ « tiMyk AKMian tftu4 Wvtiimti*,, 



Stomach on intestine is conlinned, generally with few HeiurA 
to the anal aperture, which does not communicate ditrcd; 
with Ihe exterior, but opeiu into the iKrtiomof a second chflft 
bcr, which is calleil the "cloaca" (fig. 103, i,/). Suimtd; 
the cloaca communicates with the external meilium, b>' nttui 
of the second ajwrture in the test. 'ITie first bend of tin 
intestine is such that, if continued, it would bring the anu <"> 
the opposite side of the mouth to that on which the ncrwu 
ganglion is situated. The intestine therefore, is said 10 bit 
a "Ihxmal flexure;" whereas the flexure in the case of lb 
Pofysaa is "neural." The intestine, however, in the TknuA 
does not preserve this jirimar)- ha.-mal Aexure, but is ifM) 
bent to the neural side of the body, the nervou* gaagtioQ GOoini 



I 



MOLLUSCOIDA : TUNICATA. 389 



utnatc*] b<Mwcx.'n the moiilli .ind ihc rcctunt. As 
id, titeanus U not in direct commtiniqition n-iih the 
but opCTU into a large caviljr, called the " cloaca," or 
ihamtier,' whkh, in turn, open& externally by the 
petture oflhe aninul Tills cloaca is s, large sm lined 
nbraoe which " is reflected like a serous sac on the 
ind constitutes the 'third tunic,' or 'peritoneum.'" 
doacA "it is reflected over hoth side* of the phorj-nx" 
ly sac), "extending towards its donal jart very 
^ as that structure which has been termed the ' en- 
It then passes from the sides of the phar^'nx to the 
ll, OQ trhicb the right and left lamclLx become con* 
A as to fotm the lining of the chamber into which the 
perture leads, or the 'alhal chamber.' Posteriorly, 
Offpoaie end of the atrial chamber to its aperture, its 
;mbrane (the 'atrial tunic') is reflected to a greater 
Sent over the intevline and ciicuiatory oi^ptns. .... 
C aixial tunic is Teflc<rtc<l over the sides of the pharynx, 
inter into a more or less cxnnplete union, and the sax- 
lontact become perforated by larger or smaller, more 
iimeTous, apertures. Thus the cavity of the pharynx 
a free communication with that of the atrium ; and 
kigins of the |>haryr^o-atrial a|>ertufe» arc fringed with 
king lovrards the interior of the body, n cuncnt is 
, which sete in at the oral aperture and out by ll>c 
entng, and may be readily observed in a Uving 
'■— (Hiuiley.) 

Uds sotoe poinu in the above description. Professor 
oes not agree with HiiJile)-, but believes, on the other 
hat tlie walls of the atrium simply surround the 
sac, without being reflected on its »des, and that the 
sac is therefore pro|>erly uiitkin ilie cavity of the 

ctore, the |)haryngeal or "branchial" sac is composed 
» of longitudinal and tnnsverac liars, which cross 
tr at right angles, and thus give rise to a series of 
alar mnhcs, ibc margins of which arc fringed with 
alia. These bars are hollow, and are really vessels 
en on each side into two main longitudinal sinuses, 
led " branchial " or " thoracic" sinuses — one of which 

■long the ha!mal side of tlie pharynx, whlUt the 
E along its neural aspect. Tlie function of the entire 
I pharynx a clearly respiratory. 
Mnitata possets .1 diMiiK-t heart, consisting of a slinnlc 

tube, w hich is oiicn at both cuds, and is nut provioed 



290 



MANUAL OF ZOOLOGY. 



with v,ilvca. In conscqticncc of ihis, the nrctilation in the 
majorit}- of Tunicaries is periodically reversed, the bloa! 
bein^ |>rn[>el1cit iti one direction for a cenain aurober of «•■ 
tractions, an<l bdnj^ then driven for a like ixriod in an oppfr 
site diiwrtion ; "s« iliat the two end* of the heart arc tie- 
nately artcrinl and venous." 

The nervous system consists of a tingle gu^ion pUccdai 
one side of tlic oral spcrture, between it and U)« atittti io d 
known TitikiUa, except in the aberrant form AppmdUidant. 

llie only uigans of sense arc pigmcnt'Spois, or oceUi. pbud 
between the oral tentacles, and an auditor)' capsule, socnetiiiio 
containing an otolith. Tbe:ie organs, however, do not »pfKir 
to be con.ituntly present. 

With the exception of IhiuJum and AfffrntiaUaria, all fbt 
TitNiatta arc hermaphrodite. The rejwoducttve orgaiu nt 
situated in the fold of ihc intestine, and their efterent dutt 
opens into the atrium. The embryo Tunicate is at fim gO)^ 
rally free, and it mostly shaped like the tadpole of a frag, 
swimming by means of a long caudal appendage. In i»c 
special {Maimla tuiitfyia) the larval form is destitute of a tail, 
inactive, and amoiboid, and it almost immediately attacba 
itself by means of little outward iHticesse* which it develop*. 
Ijtstly, in several instaoccx the larval caudal appendage hu 
been shown to exhibit a cylindrical ro<l-lilic twdy, which fau 
been paralleled wiili Ihc (h^rJa itarsalU of V'ertcbraica. 

Amongst the Salpians a species of alternation of geacraboM 
has been observed. A solitary Salpian produces long chaoi 
of emln^-os. which remain organically connected througbool 
their entire life. E:i<^h individual of these assodued sp 
men* produces solitary young, which are often very unlike I 
patents, and these again give rise to the aggregated (btiDt. 

The Tiinimla are often spoken of as exhibiting three o 
types of stnictiiTc, which give origin to as many sectiw 
known respectively as ihc so/itary, the t«eiai, and thetw^M"/] 
forms. In the "solitary* Tunicaries the individuals, bwert 
produced, remain entirely distinct, or, if not so primiiinlr. , 
they become xo. In the "social" Ascidians the orgiai« I 
consists of a number of loolds, produced by gemmation M^ ! 
permanently connectctl together by a vascular canal, or "stotat' 
compmed of a prolongation of the common tunic, thraofl 
which the blood circulates. Finally, in the " compound" foiM 
the tooids become aggregated into a common mass, ihev tan , 
being fused together, biii there being no inlenal unioB. IV I 
Botrylli, whidi are &miltar examples of the compoimd To"- 
cates, form semi-transparent masses, often of brilliant cstan 



molluscoida: tunicata. 



391 



ittached to vbtjoos submarine objects, and coBsistiog of 
numcfous lodids amnged in ilar-shaped groups. TItey are 
aimont always "very imall, soi^ iniuble, and coninictile, 
cfaaaging their rorm with the slightest movemeni."— {SluIc.) 

HOMOLOCIBS OF TIIR TUNICATA. — 'I'hc general rCKCmlllMWC 

between a solitaiy Ascidun and a single potypidc o{ a. Poiytoen 
\i extremely obvious ; each consisting or a double-vallcd ssc, 
containing a freely suspended alimentary cinal, uiih a distinct 
nMMth aod anus, and a nervous ganglion placc<l Ijetwecn the 
two. The chief feature in the Tunicata, as to the exact nature 
of which there h mach difference of o|iinion, i^ the branchial 
or respiratory sac Hy Professor Allman thiH is believed to l>e 
Inily homologous with the lentsicular crown of the Pi^ysM, 
and the oral tentacles of the Tunicaries ate Itclieved to t>e 
•omcthii^ superadded, and not represented at all in the yc^ 
iM. By Professor Huxley, on the other hand, the branchial 
sac is looked upon as an enormously developed pharynx, and 
the oral tentacles are regarded as a rudimentary representative 
of the tentacular (TOwn of tlie Pttlytca. Probably the most 
eoftect view of the homologies of the Tunuata is taken by 
Kolleston, who regards the " branchial sac " as the homologue 
of the gills of the ordinary- Bivalve Molluscs {LamdfibntuhMa), 
whilst the oral and atrial apertures are looked upon as corres- 
ponding to the respiratory apertures of these same animals. 

Divisioss or THE Tunicata.— By Profewor Huxley the 
feUowing arrangement of the TuQicartes is adopted : — 

Class T(;kicata. 

OMfa^ L AuUia Bntrntita/ia. 

BnnchMl mg occaprine lh« whde, or oearlir th« wholes lenglb of 
lite body ; tnUstioc Ijing on «ne side of JL [AifidiaJt, ff^iy/liti, 

OrAr IL AttiMi AUtminalia. 

AlinwnEUy caul oomplctely behind the branchuLl mc which is 
eomparuivdly unaXi {CloK^Umi, £Mif/um, &*c.) 
Ordtr III. JifHii Larvalia. 

fnBUienl Urval (arm. {Afftudintlaria. ) 

fhe following subdivisions are those ado]>ted by Mr ViocA- 
vanl: — 

CUUS TUKICATA. 



L' 



I. ^wi/id^ (SInpk AMidian*). 

Animal liapir. Aiod, wililary, or Efcnriawt ovipucm | MMi 
nalMdi Uancbiil MC kuiple t orttiipOMdin |ft— tSldHpatx) Tcgolai 
foJib. 
Am. II. CAR^raa^ CSooal Atcidian^). 

AaiMll oomfmind, fa«d \ individuali connr.-i«d bjr netpinc ivtwlsr 
profaoflttiou M the cosiiMa ttuic ibroughjK^k^^ blood \ 




292 MANUAL OF ZOOLOGY. 

(or by a cammon gelatinous 1:iate). Reproductkn efleetri \j Mh ■ 
by gemmalion from the coRimon tube ; the new indiTidnall I '' 
altuched to the parent, or becomine completely liee. 
Fam. III. BatiylUda (Compound Ascidiani). 

Aniina.Is compound, Axed, (heir tetti filled, fomiiiig » i 
in which they are imbedded in one or more gixHipi. IndindndlMt 
connecied by any inlemal union ; oviparous asd genHoipwou. 
Fam. IV. PyrcsomiJa. 

Animal compound, free and oceanic 
Fam. V. Salpidx. 

Animals free and oceanic ; alleniately soUtaiy ud icgi^ted. 



CHAPTER XLIV. 
BRACmOPODA. 



Class III. — BrachiopSda {PalHohranchUUa). — ^The membn 
of this class are defined by the possession of s body protecttd 
by a bivalve sheil, which is lined by an expansioD of the in- 
tegument, or "mantle." The mouth is furnished with two 
long cirrifen^us arms. The nervous system consists of i angle 
ganglion, placed in the re-entering angle between the galirt 
and the rectum, so that the intestine has a " neural flexure.' 

The Brachiopoda are essentially very simitar in sUuctuietO 
the Polyzoa, from which they are distinguished by the fact diti 
they are never composite, and by the possession of a biviH 
calcareous, or sub-calcareous shell. They are commonly tnon 
as " Lamp-shells," and are all inhabitants of the sea. All the 
living fonns are fixed to some solid object in their adult coDdi' 
tion ; but there is good reason to believe that many of dx 
fossil foims were unattached and free in their fully-grown c«- 
dition. From the presence of a bivalve shell, the Brachiopodi 
have often been placed near the true bivalve Mollusca (the 
LameUibrancliialii); but their organisation is very much infeW 
and there are also sufficient differences in the shell tojuso^ 
their separation. 

The two valves of the shell of any .^nirAf^m^ are aiticabdt' 
together by an apparatus of teeth and sockets, or are kept il 
apposition by muscular action alone. One of the valve * 
always slightly, sometimes greatly, larger than the other, i* 
that the shell is said to be " inequivalve," As regards tk 
contained animal, the position of the valves is anterior lod 
posterior, so that they are therefore termed respectively iJk 
"ventral" and "dorsal" valves. In the ordinaij binJ" 



MOLLUSCOIDA : FRACHIOPODA. 



293 



IT 

^KfW<» {tanuiiitnmMa/a), on the Other hand, the two valves 
Inhc shell are usually or the uimc size (cquivalvc), and (hey 
■re sittukted upon the sides of the animal ; so that, instead of 
being dorsal and ventral, they are now icimed " right "' and 
** left" valves. The ventral valve in the shell of the Bratkio- 
^oda b UMUtlty the largest, and usually possesses a prominent 
curved beak. I'he bealc is sometimes perTorated by a "fora- 
vnen," or terminal aperture, through which there U tiunsmitted 
^ muNcuLu ]>cduiKle, whereby the shell is 
sttsdtetl to uxne foreign ol>jcct In some 
teases, however (as in I.ingu/a, fig. 104}, the 
jicduncle simply passes between the apices of 
the valves, and there is no foramen j whilst in 
^Others (as in Crania) the shell is merely at- 
'%ached by the substance of the feniral valve. 
"The donal or smaller valve is always free, and 
^UKver perforated by a furamen. 
^Kn intimate strveture, the ithcll of mmt of 
ftKt BraMie/vvAi consists "of flattened prisms, 
of considerable length, atT3nj;cd parallel to 
one another with great regularity, and at a 
may acute anj;le — usually only about 10° or 
II* — wiih the surfaces of the shell."— (Carpen- 
ter.) In moat cases, also, the shell is perfor- 
med by a series of niinuic canals, which pa-ss 
finm one nicfacc of the shell to the other, in 
non or k-ss vcrticnl direction, usually widen- 
at they approach the external surface. 
canals ^ve the shell a "punctated" 
re, and in the living animal tlicy con- 
caccal tubuli, or prolongations, from the 
which are coatidered l>y Huxley as 
to five vascular procenses by which 
mtoy Ascidians the muscular tunic, or 
Mntle," is attiichni to the outer tunic, or 
**KtL" In some of the Brathiepoda (as in the RhytKkmtiHda) 
tie (hell is " impunctate," or is devoid of this singular canal 
•TiIcib. 

The inner sur&ce of the valves of the shell is lined by ex- 
Vutnom of the intecument which secrete tlie shell, and are 
«neil the " lobes " of the " pallium." or " mantle." The diges- 
titv or:pnf and muscle« oci.ii|>y a sniall space near the bealc 

(shell, which is iianiiiont-il off by a memhranouit xeptum, 
is perforated by the aperture of the mouth. The re- 
ler of the cavity of the shell is almost Ailed by two long 




An*t$Mt. itw«lnff 
■hi iBiucubiMd- 
untie 1>T wbknl^ 
thsU ii (luctwd. 



294 



MANUAL OF ZOOLOGY. 



onl processes, which arc icnncd the " anns," and froni which 
the name ur the ck&s ha$ been derived ((ig. to;, i). TtttM 
oignns arc lateral [iroIoDgalioits of (lie margios of the mnik 
unutlly of grent length, dosdy coiled up, ami (iiDgcd oo one 
side with lateral pTOcene*, or " cini." in many Bracbiopsdt 
the anns arc «up(>orted upon a more or les> complicated iMcr- 
Dal calcareous fninicwork or skeleton, which itsomeumeseaUnl 
the " carnage- spring apparatus." 





1. 8hwtiigtheihgllo>ibii>l*»|iL (Afln Wxrfnid.) 

The mouth conducts hy an ixsophagtis into a dlitino ' 
stomach, Hurrounded 1^ a well-dcvelopeti granular liver. Tta 
intestine has a " a nciiral flexure," and " citlier ends bliniUy i> 
the middle line, or else tcrmliuitcs in a distinct anas bet«ea 
the pallial Iol)ca."—< Huxley.) 

Within tlie pallial lobes there is a remarlublc syatcD «f 
more or less branched tubes, anastomosiii); with one anotho; 
and ending in oecal extremities. This, which has been tenuil 
by Huxley the " atrltl xyntcni," coinmanicales with the fOf 
visceral cavity hy menn.s of two or four oigans which are caM 
" ij.teiido-hfarts,'* an^l which were at one lime supposed to I* 
true hnrt.v " Each pseudo-heart is divided into a nana*, 
elongated, external portion (the so-called 'ventricle'), «t«^ 
communicates, as Dr Hancock has proved, by a small apiol 
aperture, with the piUlial cavity; and a broad, funnel-sluped 
inner division (the so-called ' auricle*) communicating, on At 
one liand, by a constricted neck, with tlie so-called ' vcriiridci' 
and, on the other, by a wide, i>aicni mouil), with a chanbet 
whidi occupies most of the cavity of the body proper, i*d 
sends more or less branched diverticula into the pnllial lobts.* 
— (Huxley.) 1'his system of the atrial canals has been looM 
upon as ft rudintentai}- respiratory apparatus ; but its ItuidaM 
is more probably to act as an excretory organ, and also w 
convey away the reproductive elements, the organs for whitfc 
are developed in various {>arts of its walls. By WoodmA 



Wh. 



HOU.USCOIDA : BKACHIOPOUA. 395 



Iteam are regard«d as oviducts, and it is sUled 
y hav« been foun<l to contain mature ov>i, so that 
n be little doubt but that this view of their nature is 
tct one. Kj Kollcttvn the pseudo-bcaitt arc looked 
eoTTes)X)nding with the so-called "organ or Dojanus" 

unction of respiration is probably pcrforrncd, mainly, 
lirely, by the cirri/crous oral arms, as it appears chiefly 

the bonvologous tentacular crown of the Pt4yioa. A 
3ilar system and a distinct heart are pre&cnt in some, 
lie, of the Briu/iMfwta, but this subject \i still involved 
Jerabte obscurity. In Tnr^ratula the heart is in the 

a unilocular, pyrifurm ve:ticle, placed on the dortal 
if the stomach. 

lenrouE system consists of a principal ganglion of no 
le, placed in the re-entering angle between the gullet 
rectuiQ. In those Bfachiojiods in which the v.ilvcs of 

are united by a hinge, the nervous system attains a 
levdopment, and ooiisiitts of a gangliated oesophageal 

lexes are said to be ordinarily distinct, but in some 
ey appear to 1>g united in the same imlividual. '['he 
neni of the Briuhief^ia is still shrouded in consider- 
icurity, but in some cases the young have been ob- 
} move from place to place, either by protruding their 
Sims, or by means of spines dcvelojHxl in the ventral 
be mantle. 

Brathiep«>ia may be divided into two gioups, called 
rely tlte Arluuhita and InartUulata. In the former 
n of the shell are united along a hinge-line, the lobes 
antle are not completely free, and the intevtine mds 
In this group are the recent TerSmhilida and Rhyn- 
n. In the /iMrliailata the valve* of the shell arc not 
long a htngc-line, the mantle-lobes arc completely free, 
inicstine terminates in a distinct anus. In thia group 
ZrantaJa, Diumida, and Lmguiida. 
IITIE8 OF THE Brachiopoda.— There can be no ques- 
) the close relationships subsisting tclwccii the JfrofAic- 
i MjOM, and until recently most natunUi^is held that 
W groups had strongly -marked affiniticrt with the /«- 
wAmAi. lliis view is «till held by the generality of 
t* ; but recently Mr tUIward Monie has brought forward 
I to show that the Braehi»f«da and Pi>iysMi are most 
elated to the Tubicolar Annetidcs; and this oinnion 
a previously advanced as regards the latter group by 




296 MANUAL OF ZOOLOGY. 

Leuckhart. Amongst the more striking &cts addnced in tof- 
port of this view may be mentioned the assertion thxt the k»g 
and wonn-like peduncle of Lingu/a pyramUata is noimillj 
encased in a sand-tube resembling that of a Tubicolous Anne- 
lide. The peduncle of this fonn is also contractile wid hoUor, 
admitting the blood into its interior, and the blood is stated to 
be red. In the meanwhile, however, the affiniries between the 
Brachiopoda and Polysoa, on the one hand, and the Ttimaii 
on the other, are too strong to allow of our unhesitating accept- 
ance of this sweeping change. 

Classification of the Bracriopoda (afteb DavedsokV 
Class Brachiopoda. 

Fam. I. Tmhraljilida. 

Shell minulely punctate ; ventral valve with a prominent b»k fa^ 
forated by a foirameii for the emission of a muscular peduncle, whcnl^ 
the animal is fixed to some solid object Foramen partially surrooodid 
by a deltidium ot one or two pieces. Oral appendaeei entirely or 
pHrtialiy supported by calcified processes, usually in the fonn ofaloO(^ 
and always fixed to the dorsal valve. 

Gtnera. — Tcrebratula {with TtnirahiliHa, and WaldAeimu), Tin- 
iraldia, Slringoeefhalui, &'e. 
Fam. II. T^teidida. 

Shell fixed to the sea-bottom by the bealc of the latter or vainil 
valve; structure punctated. Oial processes united in the rorm cFi 
bridge over the visceral cavity ; cirrated arms folded upon thenbelie, 
and supported by a calcareous loop. 
Cerius. — Tkectdiuia. 
Fam. III. Spiriftrida. 

Animal free, or rarely attached by a muscular peduncle. 5W 
punctaleii or unpunclaled. Arms laii.'ely developed, and entin^ 
supported by a thin, shelly, spirally roll«l lamella. 
Ctnna.—Spirifir, Sfinfirina, Cyiiia, Alkyiii, i&lr. 
Fam. IV. A'l-miietidir. 

Animal unknown. -Shell free; ^■alves unarticuUled (?). OnliiW 
supported by two lamcllK, spirally coiled. 
G^niis. — A'i}Hiiidia. 
Pam. V. RAyni-AtiHd/ii/ir. 

Animal free, or attached by a muscular peduncle issuin£ftw>'* 
aperture situated under the eilrcmity of the beak of the ventral nl* 
Arms spirally rolleil, flexible, and supported only at their origin IT) 
pair of short, curved, shelly processes. Shell-structure fibroai* 
im pun dale. 

Gi-nira. — RkyiKhonella, Pmtamtnis, Poramhoitilet, &'c. 
Fam. VI. Slrophprnniida: 

Animal unknoii-n ; some probably free, others attached, dnriaj''' 
whole or a portion of iheir existence, by a muscular peduncle, Nj 
calcified supports for the arms. Shell with a straight hingc-jine, ** 
a low triangular area in each valve. Shell -structure ntauili t** 
punctated. 

Genera. — Orihis, Orthiiina, Stmphemtna, and Leplitna. 





Vn. PnJittUU. 

Animat n&kiKiu-n. Slielt entirety ftce, or atiaclitd to marino bottumt 

' iW lubauncc «4 tlie b«ak ; -wrti cither nKulurlf ailitnlaltil, or 

in place hy muKubr Miion. No cildlicd luppoit for ilic oral 



I, CJteiula, .SrnyAaXMnt, AibUfttt. 



.VUL Cnr^itdt. 

Animal &u>l In nbnuirfne olijecM by ibc nilstiinM of Ihc iheK of 
tbe vtMnl valve Armt llcthf and tplnlly collcil ; no hinge or 
tnicBhUng procnMl; upptr or doruil valT« patdbform (i./. limpct- 

^ IX. OittMdr. 

Animal allacheH by mcaiu of a muKuIar peduncle p(t>alnG ihtoUKh 



ihe tsntral or lower I'atvr by mcani of a ilit in )i5 himlcr porlion, or 
• cinnlsr foramen cxanied in iti lubiunce Anni dciliy, valvw 
BMMicalaWiL 



Gfera,~Oiitiiia, TlrrmalU, S/ihntlrtta, jttrttrtU. 



UIVM 

Anonai &>«il liy a muicuUr prduncle punn^ oat bclw««n the bMks 
llie valra: arms finhv. uDiupportnl by I 
uiarlkiilal«d, tub-cqcivaJTe, ccxiure homy. 



of llie valra: arms finhv. uuupportnl by cua&ai proccuct. Shell 
narlkiilal«d, tub-cqcivaJTe, i 
GtHtrtt.—LmgMii, OUtu. 




CHAPTER XLV. 

mSTRIBUTlON OF MQLLUSCOIDA. 

DiSTRinuTios OF MoLtuscoiDA IN S^ACE. — The PfilysM, like 
'Uhe MMusevitia, are exclusively aquatic in their habits, but, 
*"'« the reniiiininK two cliuseK, they are not exclutivel^- con- 
I to the Ka. 'rhe marine P<ylycaa axe <>( almost universal 
oirrnce in alt seai. 'I'he freshwater /Wjumt. howc%*CT, not 
lljf differ niatrrully from ihcirmnrinc brethren in stnicture, 
<^ appear to have a much more limited range, being, a.s far as 
\Jtt known, confined lo the north temperate rone. Bmain 
daim the great nujoHiy of the described species of fresh- 
ta PttfyiM, but this is probably due to the more careful 
luiiny to which this country has been subjected. 
The Tittuata are counopolitan in their distribution, and are 
~ nd in ail se-ts, the Metliterranean appearing to he especially 
I in memlKrs of lhi» ttjiss. Four genera arc pelagic in thetf 
^U, and several are found In the Arctic regions. 

&Ajio(h«r bmity wai fomrrly corutilutcd for the rcccpllon of the ria* 
' IkToaUa Inttlb known a> Caittrl^ It liM been ihovn, bowtvtr, 
that m probably opcrculale ConJi. 




298 MANUAL OF ZOOLOGY. 

The Bracluopoda, though of very partial occunence, law 1 
wide range in space, being found both in tropical seas and in 
the Arctic Ocean. Their bathymetrical range is also voywidci 
extending from the littoral zone almost to the greatest dqthi 
at which animal life has hitherto been detected. 

Distribution of MoLtuscoiDA in Time. — The Ptljm 
have left abundant traces of their past existence in the stratified 
series, commencing in the Lower Silurian Rocks and extending 
up to the present day. The Oldhamia of the Cambrian Rocb 
of Ireland, and the Graptolita, have been supposed to belong 
to the Polysoa ; but the former is very possibly a plant, and tl» 
latter should be referred to the Hydrotoa. Of undoubted Pit}- 
zoa, the marine orders of the Cheihsiomata and Cydostam^ 
are alone known with certainty to be represented. Sc^-aal 
Palaeozoic genera — such as Fenistelia (the Lace<oial), /Wt- 
dictya, Fti/ofiora, &c. — are exclusively confined to this epodi, 
and do not extend into the Secondary Rocks. Amongst the 
Mesozoic formations, the Chalk is especially rich in FofyiM, 
over two hundred species having been already described fitun 
this horizon alone. In the Tertiary period, the Coralline Crag 
(Pleiocene) is equally conspicuous for the great number of the 
members of this class. 

The Tuiiicata, from the nature of their bodies, are not known 
to occur in a fossil condition. 

The Brachii'podii are found from the Cambrian Rocks up to 
the present day, and present us with an example of a group 
which appears to be slowly dying out. Nearly two ihouaixl 
extinct species have been described, and the class appean to 
have attained its maximum in the Silurian epoch, which is. 
for this reason, sometimes called the " Age of Brachiopods." 
Numerous genera and species are found also in both the 
Devonian and Carboniferous formations. In the Secondary 
Rocks Hrachiopoda are still abundant, though less so than in 
the Pala-ozoic period. In the Tertiary epoch a still further 
diminution takes place, and at the present day we arc not 
acquainted with a hundred living forms. Of the familirs of 
Hrachiopoda, the Productidct, Strophomtnida, and SpiriferidK 
are the more important extinct types. Of the genera, the most 
persistent is the genus Lingula, which commences in the Can- 
brian Rocks, and has maintained its place up to the pTCWnt 
day, though it ajjpears to be gradually dying out. 

According to Wood«-ard: — "The hingeless genera attained 
their maximum in the Paltcozoic age, and only three now sur- 
vive {Liiigula, Discina, Crania) — the representatives of as miay 
distinct families. Of the genera with articulated \-alves, those 



MOIXUSCOIDA : DISTRIBUTION. 



m 



provided vith spiral arms appeared first, and attained their 
maximiiin while the Terdratulida were still few in number. 
The subdivision with calcareous spires disappeared with the 
liassic period, whereas the genus Rhynchondla still exists. 
l.astly, Uic typical group, TerebrtUulida, attained its roaximum 
nt die Chalk period, and is scarcely yet on the decline." 



300 



MOLLUSC A PROPER. 



CHAPTER XLVI. 

LAMELLIBRANCHIA TA. 

Division II. Mollusca Proper. — This division indndesflwe 
members of the sub-kingdom MoUusca in which iht «nw 
system consists ef three prindpal pairs ef gait^ia ; tmithm'9 
ahvays a -well-developed heart, whieh is never composed ^ jf 
than two chambers. 

The Mollusca proper may he roughly divided into two gRU 
sections, respectively termed the Actpkaia and the Eni^yt 
(or Cephahphora), characterised by the absence or presenccf' 
a distinctly differentiated head. The headless, or Accphaloft 
Molluscs correspond to the class Lamelliiranchiata; also iir 
tinguished, at first sight, by the possession of a bivalve sheD. 
The Encephalous Molluscs are more highly organised, and« 
divided into three classes — viz., the Gasteropoda, the Ptergptk, 
and the Cephalopoda. The shell in these three classes is ^ 
very various nature, but they all possess a singular and ex- 
plicated series of lingual teeth ; hence they are groupeij Vt 
gether by Professor Huxley under the nanie of Odontophwt- 

Class I. Lamelubranchiata, or Conchifera. — Tte 
members of this class are characterised by the absence of > 
distinctly differentiated head, and by having the body moKV 
less completely protected in a bivalve shell. There are tiO 
lamellar gills on each side of the body, the intestine hii > 
neural flexure, and there is no odontophore. 

The Lamellibraiichiata are commonly known as the binlK 
shell-fish, such as Mussels, Cockles, Oysters, Scallops, tt, 
and they are all either marine or inhabitants of fresh water. 

Though they agree with the Brachiopoda in possessing » 
shell which is composed of two pieces or valves, there vx, 
nevertheless, many points in which the shell of a Lanidt 
branch is distinguishable from that of a Brachiopod, intq>K- 
live of the gical A\fl«tivte m \iit ^taictwit of tiie aoiinil i> 



HOLtUSCA: LAMELLIBRAKCHIATA. 30I 

each. The shell in the Brmkhp^a, as wc have seen, is nrdjf 
or i>n-cr ijuitc ciitiivslve, and always has ju two sides e<iuAlly 
<ilc^"tlopcd (equilateral); whilst ihc valves arc placed antcro- 
pOiicrtorly as regards the animal, one in from and one behind, 
so that they arc "dorsal" and "ventral." In %he LatK/Uibraa- 
eAiata, on the other hand, ihc l«o valves arc usually of nearly 
equil size (etiuivalvc), and arc more <lcvelo|jed on one side 
tlun on the otlter (inei|uilatcral) ; whiUi their po.siiion as re- 
Bftidt the animal is always iatfral, su ihui they are i>ro{)er1y 
tenned "right" and " left " valve*, instead of "ventral" and 
" doral." 

The rollowtnt; are the chief jioints to be noticed in connec- 
tion with the shell of any Lamellibranch : £ach ralvc of ihc 
shtU may be regarded as essenlially a hollow cone, the apex of 
wUc}) it turned more or less to one side ; so that more of the 
shell is Mtualed on one side of tlie apex than on the other. 
The apex of tlie valve is called the "umbo," or "beak." and 
is always turned towanU tlie mouth of the animal. C'onse- 
qticnily, the tide of the shell towards whidi the iimbones arc 
ttitncd is the "anterior" side, and it is usually the shortest half 
of ihc shell. The longer half of the shell, from which the 
utnbones turn away, is called the "posterior" side, but in some 
caics this is equal 10, or even shorter than, the anterior side. 
The vide of the shell where the beaks are situated, am! whetc 
the valves are united to oiic another, is called Ihc " dorsal " 
side; and the oppooilc margin, along which the Khcll opens, is 
Called the " ventral " side, or " base." 'llic Imgih of the shell 
is measured from iu anterior to its posterior maigin, and its 
4tk from the dorsal margin to the base, 
the dorsal margin the valves arc united to one another. 
' a shorter or longer distance, along a line which is called 
" hinge- line." The union is effected in most shells by 
ans 01 a scries of parta which interlodt with one another 
'teeth"), but these are sometimes absent, when tlie shell 
I to be "edentulous." Posterior to the umbones, in most 
Jtcs, is another structure passing between the valves, which 
iiiHed the " ligament " and which is usually composed of two 
psits, either distinct or combined witli otie another. These 
potts are known as Ihe "external ligament" (or the liga- 
it proper) md the "cartilafs," and ihcy constitute the 
|eacy whereby the shell is opened, but one or other of them 
vf be absent 'fhc ligament proper is outside the shell, and 
consists of a band of homy fibres, passing from one valve to 
the other just b^ind the bc-dis, in such a manner that it is put 
Upon the atrctch when the shell is closed. The cattiU^^c, ot 




302 



MANDAL OF ZOOUWV. 



internal Itgamenl, is Imlged between the hinge-lines oftbtttrs 
valves, generally in one oi more " l»ts," or in s|>ixiat proccsM 

of the shell. It coausls d 
elaxtk (ibrcs placed perpco- 
dicubrljr between the xui^ce 
by whkh it is coniaiacd, u 
that they are neccsaiily ibM 
ened ixui oorapresscd via 
tiie valves arc shut. To opo 
the shell, tliercrorc, it ii smfif 
necetnr)- Tor die aniiail i» 
rebut the musclei whi<}i trc 
provided for the clowre uf the 
valves, whereu|>on ihc clwlic 
force of the ligament andca- 
lilage if suffiacnt of iodl » 
open the shclL 

I'he body in tbe iMmA 
bratu/iiata is always endnd 
in an expansion of the doc^ 
integument, which oonsiitulR 
llie "mantle," or "palliua." 
whereby the shell is secteod 
T^e lobes oi the tiuuilk m 
right and left, and not uncnsi 
and posterior as are the aaxiAt 
lobes of the JirMhii'f«da. T(f 
wards its circtiinfcrcnce At 
mantle is more or lest ctat- 
pletely united to the ttirU. 
leaving in itx interior, irixs 
the sofl parts are Tetnovcd.! 
more or lets distinctly iropia- 
scd line, which is called ik 
"pallial line," or "impccMipa' 
(fig. 107). 

There is no distinctly diffe- 
rentiated head in any of tkc 
LamtUArandiiata, uid ibt 
mniith is simply pilaced *t Ibt 
anterior CKiremity of tbe boJF 
It is furnished with tneniba* 
ous processes or " julpi" (ow 
ally foiiT in number], but there is no dental appontw. "Dl 
moutii opcm mxo & ^viftcv, -BV&tiv (^nndittctt to a ibliBa 




fhk at.— Aniiniiiy •r ■ Unix MolluM 

Dunllc-lvL* vtA hair Iht ■iph'^iu an r«- 
wtrnA. 1 1 RtifilniaTT liplHwt. ill* 
•mwi lni]i(«bn| Ac ilirectioii at Ox 
Evmila: d <i Adduclnv muiclH; # 
Cillti k llHtt; /Moulh. tarnuxlttl br 
(/»ltkiil(Ml|>;/>''(«<; rAoui: mCuI 
•dg« oT iIk HBBnifo. {AiU* WssdwaM-) 




A: LAMELMBRANCHIATA, 



303 



On the right side of the stomach, and opening into 
roany nKCS. a blind sac containing a pctiiliat irins- 
jiglasEy body, whirJi is known as the '■ cij-sUllinc stylet," 
le ftinctioDB of which arc absoUildy unknown. The 
Ekc las its fire: flexure neural, pcrfor.ilcs the wall of llic 
land icnuinatcs po&tcrioTly in a distinct anus, wliich is 

Ujilaced near the mpiraiory apenuri.'. The liver is large 
ll develoiMid, but there are no ulivary glands. 
re ii always a diatinct heart, coin|>OM:d either of an 
and ventricle, or of two auricles ami a ventricle. The 
le propels the blood into the arteries, by which it is dis- 
1 through the body, I-'rom the AncTics it paucs into 
DS, and is conducted to the gills, where it is aerated, 
Ffinatty relumed to the auricles. 

) respirator)- organs in all the LamtHibramhiala conust 
Flamellifonn gilu, placed on each side of the body (fig. • 
\. In some cases there is only one gill 00 each ude of 
pdy, the external pair oif bran<:hiw being al»ent. The 
K in the form of inembmnous itbtcs, com|ioscd usually 
bar rods, which support a network of capilUry vessels, 
j/t covered vith ribntinf cilia, whereby a circulation of 
tter b maintained over their surfaces. In some bivalves 
Mtns of the mantle are united to one another, so that a 
I branchial chamber is produced ; an<l in the others the 
lements for the admission of fresh and the expulsion of 
ntcr arc c(|ually ]>crfcct, though there is no such cham- 
in thoec in which the nuntlc-lobcs are united at their 
V, there arc two orifices, one of which scr^-es to admit 
rater, whilst the ctfcic water is expelled by the other. 
aqtins of these '• inhalant" and "cxhalant" apertures 
en drawn out and extended into long muscular lubes 
IkhODS," which may be either free, or may be united to 
ptber along one *iilc (ftg. 106, si), and which can usually 
Ktally or entirely reinictcd within the shell by means of 
muscles called the " retractor-muscles of the siphons." 
si|>lions arc more especially characteristic of those La- 
atKhs which spend their existence buric<i in the sand, 
ling their respiratory tubes in order to obtain water, and 
•ach nutrient particles as the water may contain. The 
W or abtence of retractile siphons can tie readily deter- 
merely by inspection of the dead shell. In those 
( in which siphoiis arc not present, or if |iTdcnt are not 
Ic, the " pallia) line " in the interior of the shell is un- 
in its curvalufc. and presents no indentation {Intcjja- 
i). In those, on the othet hand, in which i«tiw:lAe 



^04 



MANUAL OF ZOOiXJGY. 



Biplioos exi&t, the pcillial tine docs not nin in an aiAnfcca 
carve, )>ut is defected inwards posteriorly, so xi lo Ibnn a 
indentation or bay, which U iCTioed the "pdUlial itruu,*or 
" si|)hon.il inipre»ion," and is causted l>y the inscrtioa of 6t 
retractor-miiscle of the itiplion. These bivalves in whkJi tbtt 
sinus exists form the section Stnu-ju/Zia/ia (Ag. 107, i). 




<niln lallul UiH. * T*^ft fatUum, a iinnry AtV <*iik ut iaiiBU4 giadta, 
f Frr-M f/ii//i.i», •, riunumjMiT ihill (ariir VloeAinail • IWU ItK* 

The nervous system of the LameiliiraneMiata is comiKMed <f 
the three nnnnal s^^^k'^ — '^^ cej>halic, the pedal, and tk 
parictO'Splnnchnie or bmnchiaL The so-calW "oigiit rf 
Bojanus' of the bivalves is doubtless mainly conceiaed te 
excretion, itnd in all probability represents the kidney. Tbw 
is one of these organs on each side of the body, each cmr 
posed of two sacs separated from those of the opposite vik 
by a venous sinus. Or it may be looked upon as a doiMt 
organ composed of two bilaterally symmetric^ halves. Hit 
sittuted jtLst below the " pericardium," and cooununicate tA 
it and also vrith the man lie -cavity. Though undoutitcdljt fd- 
fonningthe functions of a kidney, tlie oi^pui of Uo^anus u ilw 
connected in some cases with reproduction, And it KppeinH 
correspond to the " pseudo-hearts " of the BrathiopMa, 

The majority of the bivalves are dicDcio^ts, but in soBCll* 
sexes arc united in the same individual. The youni X 
hatched before they leave the parent, jmd arc, when fin( Blf 
rated, ciliaicd and frce-swiinming. 

The muscular system of the LamcUibranchs ts weU ie* 
loped. Be:tides the muscular maj^in of the mantle, and tit 
miudcs of the siphons (when these exist), there arc alwpv 
sent other mitsdes, of which the most important are the »* 
cles which close the shell and those wliich furm the "fo* 
(fig. 106,/). The "foot" is present in ihc majority of bi«'al>^ 
though ii is iiol «ucl\ & fAi\Vvn% ^<u.Vix«, a& In the GaOtnfii^ 



M 



UOLLUSCA : I.AMRLURKANCHIATA. 



30s 



• esMnti-illy a niusmhr organ, developed upon the vcntnl 
bee of th« body, its rcUactOMttuscIcs usually It-aving di&- 
:t imprcsswDs or scars (the "pedal impreaions') in the 
trior of the shell In manjr the foot Hubsen-es locomolion, 
[ bt the attached bivalves it ix rutliinenlar)-, :md in othent (as 
[be ScallofMJ locomotion is effected by the sllemntc ojxning 
I closure of the valves. In some — such as the onlinniy 
md— the foot is subsidiary to a spcciaJ gUnd, which secretes 

tuft of silk^ threads (" byssus") whereby the shell is at- 
hed to foreign objects. This gland secretes a viscous 
terial. which the foot moulds into threads. 
n»c valves of the shell aic brought together by one or two 
soles, which are called the "adductor muscles" — those 
ftlves with only one being called Afenomyaria, whilst those 
ich possess two arc termed Dimyaria. In motit there are 
> adductor muscles (6g. 106, a a') pawing between the inner 
Cues of the valves, one being pbced anteriorly in front of 
I moulh, the other posteriorly on the ncurnl side of the in- 
line. In the monomyaiy bivalves the posterior adductor 
he oivc which icmains, and the anterior adductor is absent, 
e adductors leave diMinct "mu.scular impresnons" in the 
erior of the shell, so that it i.1 oiy to determine whether 
n has been one only in any given specimen, or whether 
» were pre«enu 

rbe lut>it« oJ the /^mHlitrafuhiata arc very various. Some, 
^ at the Oyster (Oi/frt)), and the Scjillop(/'«<ffl). habitually 

on one side, the tower valve being the deepest, and the 
X beii^ wanting, or tudimentary. Others, such as the Mii'iscl 
fftiliu) and the Pintui, sic attached to some foreign object 
' an apparatus of Uireads, whidi is called the " b)'ssus," and 
leaetod t>y a special gUnd. Others are fixed to some solid 
xly by the substance of one of the valvei. >lany, sudi as 
tMj^, spend their existence sunk in the »nd of the sea- 
Dre or in the mud of estuaries. Others, a.s the Pkaiades and 
UmSm*/, bore holes in rork or wood, in which they live. 
Biny, many arc permanently free and locomotive 
The Lameiliiranthiata arc divided intn two sections, accord- 
t as respiratory siphons arc absent or present, as follows : — 
SKcrio>< A. AsiPHOMiDA. — Animal without respiratory 
ihofls ; mantle-lobes free ; the pollial line simple and not 
lented {/ntexrv-fiiJiieUia). 

This section comiwiscs the laniiltes Ostreida, Aviaiiidtt, ity- 
)itt, Arcada, TVigmiada, and Unionida. 
EtJtcnoN 1). StrHONiDA.— Animal with resiuratory siplions ; 
atk^tobcs note or less miiied. 




306 MANUAL OF ZOOLOGY. 

Two subdivisions are comprised in this section. In Ibe 
first /Ae siphons are short, and the palliai line is simple (Intqn- 
pa//ia/ia) ; as is seen in the families Chamida, Hi^nritHa:, 
TVidamida, Cardiada, Liuinida, Cyeladida, and Cypriniim. 

The second subdivision (^Sinupalliaiia) is distinguished bf 
the possession oi/ong respiratory siphons, and a sinnated paBai 
line, and it comprises the families Venerida, Maetrida, TiUtniJt, 
Solenidie, Myacida, Anatinida, Gastrochattida, and Phaiadidd. 

SvKorsis OK THE Families of the Lahellibiahchiata. 

Section- A. Asiphosida. 

F.im. I. Oj/r/jVir.— Shell inequivalre, di^tlf ■ne<jiiikteTal,(cn> 
aUacheil ; hinge usually edentulous. Ogament internal. Lobs 
of the mantle entirely separated ; the foot small and byuiTnoK, 
or wanting. A single adductor. IN. Geo- Ottna, Jittm, 
Sfomiy/us, i£v. 

fam, 2, Avicu/ida. — Shell inetjuivalve, very oblique, itladitd If 
a byssus : hinge nearly, oi quite, edentulous. Mnntle.tobei {at; 
anterior adductor small, leaving its imprcuion within the umbo; 
posterior adductor large and sub-central. Foot smaU. IIL Go. 
Ai-icula, laxtranmi. Pinna. 

Fam. 3. JIfytilid.i. ^-SiitW eqiiivalv^ umbones onlerier, hinge eilei- 
tulous ; anterior muscular impression soull, poslehor iuB- 
Shell attached by a byssus. Mantle-lobes united between tM 
siphonni apertures. Foot cylindrical, grooved, and byssifenu 
in. Gen. Alyiiius, Atodiola, Dnissena, 

Fam. 4. Arcaiiii, — Shell equivalve ; hinge long, with many wmi- 
like equal teeth. Muscular impressions nearly equoL .Mintk- 
lobei se])arated ; fool laige, bent, and deeply grooved. IIL Go. 
ArfUj P/vtHin-uIuj, Cutullaa, 

Fiiiri. S- Trij,viiiaitir.—SheU equivalve trigonal; hinge-teeth ft*. 
divcTginc ; umbones directed posteriorly. Mantle opeuifM 
long and bent. 111. Gen. TrigoHia, Axinus. 

Film, 6. Unionidit, — .Shell usually equivalve, with a large ritcml 
ligament. Anterior hinge-teeth (hick and striated ; po^I^1i( 
laminar, or wanting. Mantle. lobes united between the sipbcot 
apertures. Fool very large, compressed, byssiferous in tli«£i7i 
IIL Gen. Unio, AiioJsn, MtUltria. 

Section B. Siphomda. 

Subdh-hioH I. Iiilcgro-paltialia. — Siphons short, pallial line amplt 

Fam. 7. Chamula. — Shell inequivalve, attached; hingt-leeth M 
(two in one valve and one in the other). Adductor impreaii>> 
large. Mamie closed ; pedal and siphonal orifices imill w* 
nearly eijual. Foot very smnll. 111. Gen. Ckama, Dkeni. 

Fii'i. 8. llippHrilidit. — "Shell inequivalve, unsymmctrical, (hii 
attacheil by tlie rii;hl umlio ; umbones frequently catneitld; 
structure and sculpturing of %ti1vcs liissimllar ; ligament iottras'i 
hingc.tcclh 1-2 ; adductor impressions 1, large, those of thtW 
valve on prominent apophyses; pallia! line simple, sub.Tnaiiiiitl- 
— tWoodwaid.^ \\\. Oen. Hit^riUi, BaJuiiUi, CafrinS*- 




I 



MOtLUSCA: LAMELLIBRANCHIATA. 



Am.9. TridsrmUr. — 5hcll(<]uir*!>« ; lii^xtnrnt tittmil; muicnlir 
ItBpNUiaai blcdilctl, lub-ccnlral. Animal allxhol \ff a Inroiu, 
orlTM. M«ntlc-h>bci ciitenHvd}r united i p«clil aptrtura liiTOi 
(iphiMul ohAcc* mronniUd by ■ thickoned pillml MHtler. Foot 
linger-like owl brislfeimu. tlL Gen. T*idoita. 

Am. lo. CjrJiaJj. — SbcU cquiralve, hnit-ihtpcd, wilh nduuine 
rlln ; onlittil imh t ; Ittcnl teeth t'l, in e»eh valve. M&nite 
mtx in ftota, liphoni ukuiII* very thoil ; fool lurcc, tkkle- 
Uipod. IIL Cr«B. Can/uim, //tmifitrJiMiH, Cnwiartflurfli. 

Am. II. Zn-VitA^.— Shell otbicukr, lai fmt binge-teeth t ort; 
Utcial lectb I -I. oi cbwleic. M*Ule-lobei open bdow, with 
one ot two tiphoiul oriruci bebiad j foot dongoted, cylindrical, 
ot ilT«p-i)uped. III. (ien. /juina, DifltJ-mU, XtUia. 

Fiim. II, CjtbJUir. — Shell luWtblculaf, clnieil ; hin][e irith 
caidlul ud Uttnl leclh ; linmrni cilernftl. Minilc npcii m 
froAIi 1-1 MfihoDt, more oi Te» uuilcJ. Kool larj^, lon|^«- 
•lup«L IIL Gen. C^iai, Qrrttu. 

Kim. ij. 0'A'*''^''-~SlieU cquiiralve, cloted; ligamenl ruernal; 

^cudiMl ieclb 1-3 in e«di viuve, knd ntually a pdtletinr toolh. 
Huitle-lobes*nitodbcbindby Kcunainpintcd viih two (iphonaJ 
oiiflon. Fo«i (hick, lad tODfac-fluped. IIL Gen. Cy/ruu, 
jtittirtt, /t*Mrdia. 
fruit 
liM 



I 



KtiM II, &Mi.^fia&.— Rctpinitoiy tiphont lufe: p*Ilul 
Use tinuted. 

Am, 14. Knwri^.— Shell feguhr, nb-orbicalu or oblong ; liga- 
meat ctlenial{ hlneewlth uiuall^ jdiTergingleelh InctdirBlve. 
Anlnal sMutly free ind locnniiihve; nitnile with a rather larj^ 
•ntarior optninj; ; fiphont «iie(|uil, moie m teu utiileit. foot 
loai^M-ihaptil, compreiMil, MnMlimes grooved anil byMiferuuk 
III. Cicn. Ifiuii, QnM/nAi, Vnumfit. 

Am. 15. .V»iinJ.r.—'Ah<:)X e4Divalv«, trininal 1 hinge wilh two 
illvefffins urtlinil tevih, and uiuaUy villi tnteriat an<l posterior 
lalenJ tecih- Mamie more or lc*> open in front 1 liphant uniled, 
with fringed ocifam ; fool cvcnpccHd IIL Gen. JAif/m, 

Ai*. 16. TrBlmda. — Shell free, nnalty equivilvo and cloMdi 
Canlinal tceU l at ntoit, lattrali l~l, vjrnctiinei «noliii(;, Liga- 
meiM on t)te *honeit tide of the ihell, socnetitDn intenial. 
Maslle widely open infroDL Siphons lepirote. long and tlendert 
ipOK longuc-iha^cd, compieued. IIL Gen. TtSma, PtitmmMt, 

ZttKMJU 

Am. 17. .Mniii/A — Shell elongated, gaping at luith endk: ligament 
•KI«niBl 1 liia^teeth ukually i-j. Siphonv thorl and nnited 
(!■ ibe leoE'ahFlleil genera), or longer and partly teparat* (in th« 
gncn wilh thoTler khdli). Foot very large and powerful, (iilt* 
mlMfed taio the bnnchial liphou. 111. Ceik Silm, CatttUtUt 

Am. iS. AtfMidM- — Shell caping piMcrioHy. Mantle ahnott 
cntlfely tloavd ; tiph<uit umteil, portly or wholly retiadile. Focrt 
very vmXL III. Gen. Jif*, Ab></mh, Gtyiimtni. 

Am. 19. AmatiniiK. — Shdl olten ine<)iiival*«, vilh an eitanal 
liC«n«nl. Mantle-lobei more ot le** nnilcd ; tiphont long, moie 
or lc» waled. Fool nnalL DL Gen. Amti»t, fMtitmj*, 
ilj^duma. 



I 



308 MANUAL OF ZOOLOGY. 

Fain. 30, Gaitnxhanida. — Shdl eqniTclTc, gmpinb with tbin efa- 
tulous valves, sometimei cement«l to ■ oilmeout tabe. Ifdk- 
margini thick in front, united, with m snail pedil *pcnnL 
Siphoni very long, united. Foot finger-iluped. HL Gol Cm- 
rochams, Saxirafa, Atftrrilliim. 

Fam. 21. /'jt«/<i</ub.— Shell g*piae*t both end^ withoolhiBteo 
ligament, often with accessoi; vatvei. Animal chib-ih^nlv 
worm-like, with a short tmncaied foot Mantle dosed ia biM. 
Siphons !on^ united to near their extremities, HI. Ge& PUtt, 
XyUphaga, Tatda. 



CHAPTER XLVIL 
GASTEROPODA. 



Division Encephala, or Cephalophora. — The reuiaiinpi 
three classes of the Mollusca proper all possess a distmcdj 
dilTerentiated head, and ore all provided with a peculiar masi- 
catory apparatus, which is known as the " odontophore." Ftf 
the first of these reasons they are often grouped together undo 
the name Encephala ; and for the second reason the; ut 
united by Huxley into a single great division, under the mine 
of Odantophora. Whichever name be adopted, the three cUsmi 
in question (viz., the Gasteropoda, Pteropoda, and Cephai^iii) 
certainly show many points of affinity, and form a very oanml 
division of the Mollusca. The Pteropoda, as being the tawOl 
class, should properly be treated of first, but it will conduce tP 
a clearer understanding of their characters if the Gaittnfik 
are considered first. 

Class II. Gasteropoda. — The members of this cUsi at 
characterised by being never included in a bivalve shell ; loco- 
motion being effected by means of a broad, horizontally to- 
tened, ventral disc — the "foot;" or by a vertically fiattowl 
ventral, tin-like organ. Flexure of intestine haemal or neonl 

This class includes all those Molluscous animals which A 
commonly knon-n as " univalves," such as the land-snail^ lOt 
snails, whelks, limpets, &c. The shell, however, is sometoW 
composed of several pieces (multi\-alve), and in many that' 
either no shell at all, or nothing that would be generally iWf 
nised as such. In none is there a bivalve shell. 

In their habits the Gasteropods show many differencHiW* 
being sedentary, but the great majority being free and loafflO' 
tive. In these latter, locomotion may be effected by the aw- 




blions ind expansions of ft musmliiT foot ; but 
Pthe power of sirimming freely by means of a 
■like foDL 

S the Gaskropeda the body is ntuyramctncal, and is 
liially, " the rMpintory otKuu of the led wide being 
)hi«i"— (Woo<lwar<l.) The body i* enclosed in a 
hich is not divided into two lobct u in the I^uui- 
bat is continuous round the body. Locomotion 
>y means of tbc " foot," which is ustiJilly a broad 
ic. developed upon the ventral surface of the body, 
)tbitin}( any distinct division into parts. In the 
hovcver, and in the Wtng-shells {StrombUa), the 
I a division into three portions — an anterior, the 
I ;" a middle, the " meaopodium ;" and a potferior 
etapodium." 

again, the upper and lateral surfaces of the foot 
d into muscubr side-lobes, which arc called " epi- 
many cases the mciapodium, or posterior porlion 
I secretes a calcareous, horny, or fibrous plate, 
ed the "operculum" (fig. 109,0), and which serves 
^irifice of the shcU when the animal is retracted 

Pin most of the Gatttrspeda is very distinctly 
■ad is provided with two tentacles and with two 
arc often placed upon long stalks. Very often 
located retractile proboscis with car-sacs, contain- 
at Its ba<[e. The mouth is aome- 
icd with homy jaw^, and is always 
th a singular masticator}' appara- 
ihe "tongue" or "odontopnore" 
' It consists essentially of a cartiU- 
on, supporting, as on a i>ul!ey, an 
which hears a long wrics of itans- 
ised teeth. The ends of the strap 
ed with muscles atuchcd to the 
mer !iurface of the hinder exircmi- 
canilaginous cushions; and these 
their alternate contractions, cause ^^ x<it.-tn€m* 
strap to work bsckwardu and for- «( <)m ihi(ul rib- 
he end of the pulley formed by its 
The strap coRscquendyacta. after 
rf a chain-uw, upon any subsUnce 
is applied, and the rebuking wear 
IS anterior teeth are made good by the incessant 
t of new Icctfa in the secreting sac in which ibe 




phun oT Ibe <tiar 
D«i Whelk \Bm' 

micnitM (Afta 
Wmxlmrl) 



L. 



310 



MANUAL OF ZOOLOGY. 



hinder end of (he strap b lo<tg«d" — (Husley.) Th* le«h 
the od<>iito|)hi>re ("lingual teeth") are composed of tilica. ; 
arc usually arranged in a central (" rachidian ") and rwo bieni 
("pleural") rows. The mouth leads by a gullet into a ditliDct 
stomach, whidi Is sometiines provided with calcareous plMct 
for the trituration of the food. The inicstine is loo);, and in 
first flexure be commonly " haemal,' or towards that xide oi iIk 
body on which the heart is .situated ; though in Kome the flexure 
is " neural." I)i»^tin<-t olivary glands ue tuuaJly imsaU, lad 
the liver is well developed. 

A disuiict hcan is usually pment, composed of an aoride 
and ventricle. In m.iny Gastcropods it h.is been shown ihU 
the blood-vcsscis form closed tubes, and that the onerics and 
veins ore connected by an intem>ediatc system of captUoiMk 
inrtead of merely communicating tlirough the tntcnttcei aad 
Ucunte beiwcen the ti«u«s. It %eems also certain that, ii 
general at any rate, lhcr>; is no direct connection between the 
blood-ve&seU and the outer medium, though, in soinc aaa, 
such a communication seems undoubtedly to exist. RetfB» 
tion is very riuiously cflectcd ; one great divisioo [Bnnckt 
gajtervfaifa) being construcleil to breathe air by meini t( 
water; whiLit in another section {PHlmegcutefv^a) the «■ 
ration is aerial. In the former division nrqtiration m^w 
effected in three ways. Firstly, there may be no speciiW 
respiratory otgan, the blood being simply exposed to the nicr 







• Urmd*! 



[r the thin walls of the manlleovity (as in some of the flj*^ 
fwia). SeooiMlIy, the respiratory organs may be in the foRi^ 
outward processes of the integument, exposed in tufts ua ^ 
bock and sides of the animal (as in tlie yHdihramMH^ 
Thitdl;f, the respiratory organ* txt in the form of pc c ti MW 






MOLLUSCA: G.\STEROPOI>A. 



3" 



or ptnine-Ukc bnDchiic, contained in a more or less tomptcte 
bruirhial chamber fonncd by an inflection or ihe manile. In 
many mcmbcn of this last section the water obtains access to 
the (t'"* ^y means of a tubular prolongation or folding; of the 
uuinile, forming a " aipliou," the elTeie u-utcr he'mg expelled by 
ther p(>vterior siphon iiimilarly cunMniotml. In the air- 
■thing ( in«[erOi|>0<i!', the breathing oi^an in m the form of 
ipulmoniiry chamber, rormc<l by an infection of ihc mantle, 
~: having a distinct aperture for the admission of iiir. 
I'hc ncTvou« system in the G-istftvpoda has its nomul com- 
poetliou of three principal pairs of ganglia, the supra-tcsopha- 
geol or cerebral, the infra-oeiophagcal or pedal, and the parieto- 
splanchnic ; but there is a tendency to the a^igre^tion of these 
in the neighbourhood of the head. The organx of sense arc 
the two eyes, an<I aiidilory cajisules placed at the bases of the 
tcntnrlcs. (he latter being tactde organs. 
I'he sexes are mostly ditCtncI, but in some they are united 
the same indix'klual. The young, when first hatched, are 
Mv/ provided iriih an embryonic shell, which in the adult 
ay iKcome concealed in a fold of the mantle, or may be 
ely losL In the branchiate (iasteropodt the embryo is 
ted by a small natiliiuiil shell, withm which it can en- 
retract ilsclfi and it is enabled (o swim freely by means 
tin abated lobes arising from the sides of the hea<l ; Ihiu, 
tmany respects, resembling the pcimaneni adult con<lilion of 
riavftda. In the branchiate Ginter,>fii>ii^, however, of 
lit waters, the young do not possess these ciliated buccal 

SJitli iff ikt GastfTopoda. — The shell of the Oasteropods ia 
■^mciOKd either of a single piece (univalve), or of a number 
*|f putc* succeeding one another from before bncltwards (mul- 
^"alve). The univalve shell is to be regarded as essentially 
|Oone, Uic apex of which is more or less oblique. In the 
ni|]lrst form of the shell the conical siiape is reiamcd without 
^y alteration, as is seen in the common Limpet {,P<U^la). 
' the great majority of ca.ses, however, the cone is consider* 
■ly clnn^ted, so as to form a tube, which may retain this 
>t|>e (as m Denttilium), but ia usually coiled up mio a spiiaL 
^^ "i|Hial univalve "(fig. no) may, in fact, be looked upon 
~~^ the typkal form of the slvell in the Gailtrvfeda. In loine 
•et the coils of the shell— termed technically the " wliojia " 
'%n hardly in contart with one another (as in Verm/tm'^. 
'ore common)}' the whnrU are in contact, and ate ko amalgn- 
"" " that ihc inner side of each convolution is form«t by the 
sting whoiL In some cases the whorU of the shell 



312 MANUAL OF ZOOLOGY. 

are cmled round a central axis in the sanu flaiu, when the 
shell is Slid to be " discoidal " (as in the common fresh- 
water shell Plamrbis). In most cases, however, the whorii 
are wound round an axis in an oblique manner, a true s{Hnl 
being formed, and the shell becoming "turreted," "trochoid," 
"turbinated," &c. This last fonn is the one which majrbc 
looked upon as most characteristic of the Gasteropoda, the sbdt 
being composed of a number of whorls passing obliquely round 
a central axis or "columella," having the embryonic shell v 
"nucleus" at its apex, and having the mouth or "apetture" 
of the shell placed at the extremity of the last and laigesKtf 
the whorls, termed the " body- whorl." The lines or gnxins 
formed by the junction of the whorls are termed the " sutures," 
and the whorls above the body-whorl constitute the " spire ' of 
the shell. The axis of the shell (columella) round which tht 
whorls are coiled is usually solid, when the shell is said tob« 
" imperforate ; " but it is sometimes hollow, when the shell ii 
said to be "perforated," and the aperture of the axis near the 
mouth of the shell is called the "umbilicus." The maiginof 
the " aperture " of the shell is termed the " peristome," and is 
composed of an outer and inner lip, of which the fonnn ii 
often cKjianded or fringed with spines. When these eipiD- 
sions or fringes are periodically formed, the place of the moui 
of the shell at ditferent stages of its growth is marked br 
ridges or rows of spines, which cross the whorls, and are cilled 
" varices." In most of the phytophagous Gasteropods {Hflo- 
stomafa) the aperture of the shell (fig. i lo, a) is unbrotenlj 
round or " entire," but in the carnivorous forms {Siphonnsti- 
mafa) it is notched, or produced into a canal (fig. no, l'\ 
Often there are two of these canals, an anterior and a posteriw. 
but they do not necessarily indicate the nature of the food, n 
their function is to protect the respiratory siphons. The 
animal withdraws into its shell by a retractor-muscle, »hidi 
passes into the foot, or is attached to the operculum ; its sor 
or impression being placed, in the spiral univalves, upon ll" 
columella. 

In the multivalve Gasteropods, the shell is composed rf 
eight transverse imbricated plates, which succeed one anotbff 
from before backwards, and are imbedded in the leatherf* 
fibrous border of the mantle, which may be plain, or imyl* 
beset with bristles, spines, or scales. 



MOLLUSCA : GASTEROPODA. 



313 



CHAPTER XLVIII. 



DIVISIONS OF THE CASTEHOPODA. 

The Gusltivfcda are divided into two primary sectioiu or 
sub-cbsscs, according as ihc rct|)iratoTy organs are actn]>tcd 
for breathing air directly, or dissolved in water: termed 
rcfpectivcly the Pvimenifera or I'ulin^asttnp^a, and the 
Bmndiifera or BriiMfiiegasffr{t/^\t<t. 

Sl'B-ct.ASS A. Bkamchifera or Branxhiogasteropoda. — 
In llii* >ul>«lass rafiratitn is a^uatU, efiectcd by the thin 
walls of the mantle-cavity, bv external branchial tuflii, or by 
pectinated or p)iim«-likc ^IK, contained in a more or less 
complete branchial chamber. Flrxure 0/ intt^iitt hamal. 

This siib-cUss comprises three orders — viz., the Pr^o- 
iranehiala, the OfistMraneiiata, and the Nuiltobrariehiata or 

OkDBA L Pbosobranchiata. — ^Thc members of Oils order 
are de6tied as follows : — ''^AMcmen well developed, and pro* 
tectcd by a shell, into which the whole animal can usually 
retire. Mantlt fomitng a vlulied chamber over the back of 
the head, in which arc placed the excretory' oii6ces, and in 
which the branchia: are almusc alw.ij's lodged. Braixhim 
I>ectiitaled or ptunw-likc, situated {prosoti) in advance of 
ihe heart &«iv distinct." — M.-Edwards. (Sec Woodward's 
• Manual.') 

1~be order Prcs^ratKhiala includes all the most charactei^ 

isiir m<.'n)l>en of the Branchiate (iaNteropodt, and is divisible 

into Iwu scction.t, termed respectively Sifhenosiemala and 

H«bitomala. acocnding as the apcrttirc nf the shell is notched 

or produced into a canal, or is simply rounded and " entire." 

The StfAmMlfmafii, of which the common ^Vhelk {Bukj- 

UMfi^itum) may be taken as an example, are all marine, 

are mostly carnivorous in their habits. The following 

Ibniliei arc comprised in this section: — Sfvmiuia (Wing- 

thttls), MuridJit, Buainiiiit (M'helks), C^itiie (Cones), Vitli- 

tida, and Cyfratda (Cowries). 

IIk H^tlomata, of which t)ie Common Periwinkle (Litto- 
rnu litl«rta) i* a good example, are cither spiral or Umpet 
ihipcd, in some few insiancei tubular, or multivalve ; the aper- 
lurt of the shell being in most cases entire. They arc mostly 
ptitiKatcrs, and they may be cither marine or inhabitants « 
&eih water. The following fsmilies are included in this scc- 
tJMli— Aisflif*^. P}raiHiiitiiiJa, CerilkiadiZ, iUianuiJa, T^trri^ 



314 



MANUAL OF ZOOLOGY. 



tellida, Littor'mida (Periwinkles), Paludmida (RiveraaS^i 
Neritida, Turbmida (Top-sheUs), Haiiotida (Ear-shells), Bt- 
surellida (Key-hole Limpets), Calyptraida (Bonnet Limpeb), 
Patdiida (LimpcU), Dentaiida (Tooth-shells), and CAtAwiiif. 




Fig. no — GaiUropodjt a HDl«toni:i(oi» ■hell (Tutrriftia comrnwrniii', 
i SiphoncAtDnutaui ibcU iBmmnmim tuuiarMim'). 



Order II, Opisthobranchiata. — This order is defined u 
follows : — 

"Shell rudimentary, or wanting. Branchia arborescent or 
fasciculated, not contained in a special cavity, but more or less 
completely exposed on the back and sides, towards the rear 
{opisthen) of the body. Sexes united." — M.-Edwards. (See 
Woodward's ' Manual') 

The Opisthobranchiata, or "Sea-slugs," may be divided ifl» 
two sections, the Tutibrancltiata and Nudibramhiata, accotd- 
ing as the branchite are protected or are uncovered. 

The first section, that of the Tectibranchiata, is distinguished 
by the fact that the animal is usually provided with a shell, 
both in the larval and adult state, and that the branchix uc 
protected by the shell or by the mantle. Under thb fanutf 
are included the families of the Tomatellida, Bullidm (Bubble 
shells), Aplysiadtz (Sea-hares), Pleiirobranchidm and PhylMiaiM, 

In the second section, that of the Nudibranchiafa (fig. iii), 
the animal is destitute of a shell, except in the embryo condi- 
tion, and the branchia; are always placed externally on the 
back or sides of the body. This section comprises the families 
XhridiZ (Sea-lemons), JVilMiiada, dSoKAs, PhylUrhoida, and 








ytthdit. Specimens of the Sn-sUigs and Scalcmoiis may at 
any time be round creeping about on sca-M^eds, or uibithed 
to the under surface of stones u 
low water. The bead is fumlxhed 
with tentades, which appear to be 
nuher conaected with Uie »en«c of 
smell than to be used as laciiti; 
oi;gani ; and bchiod the (cntacles 
•re generally two eyes. The ner- "tii',J^ 
vous system is extremely well de- 
veloped, and would lead to the belief that the ■-.clu 

are aunoogsl the highest of the Gasfavfwta. l^cumouon is 
cflfected, as in the true Slugs, by ciecping about on the flat- 
tened foot 

OkDRR III. NtKLRODRANCKIATA OR HXTTEROPODA, — This 

order in defined by the following characletlilics: — Animal 
provide*! with a shell, or not, lite-swunminK and pelagic; 
locomotioa efiTected by a tin-like tail, or by a Ian-shaped, ver- 
ily flattened, ventral fin. 




( Shdli/FuDllifDnc. [Aft«W«>it«rd.I 



The littfrofcita are pelagic in their habits, and arc found 

^rimrainK ai the siirfece of the sea. TTiey are lo he regarded 

^k the mwt hit;h1y organised of all the Gasterefn-da, at lli« 

^fcic time that they arc not the mo«t tyi>ical members of ilie 

cioM. Some of them can retire oomidetely nithin their shells, 

dosing them with an operculum ; but most have lar||;e bodies, 

and the shHI is either small or entirely wanting. They swim 

by means of a flattened ventral tin, or by an elongated tail, 

and adhere at pleasure to seaweed by a sniall sucker siniated 

on the side of the fin. Thew; or>;ans are merely modifications 

of the foot of tlw onjijuuy Ga^teropods ; the fto-Vikc t&i\ \xfm% 




3i6 



MANUAL OF ZOOLOGY. 



the " mctapodium " (as shoim by its occastonalty canytog n 
operculum), the sucker being the "inesoiiodiutn,'' and (hete»- 
tral fin beins a modified " propodtum." The " epipodia * m 
apparently ait<7giMher wanting. Respiratian is somcdmet cv- 
ned on by ilUtinct Iinmrhijc, but in many casec tbcM ut 
n-anting, and the (unction is perfonncd simply by the walls sf 
the jvtllinl chamber. 

'I'hc H^trefeda are divided into the two Eamilies FmHit 
and Atfattida, the former characterised by lui%Sng a snuU tbdl 
coveting the cinmlaloi^ ami rcs[>iratory organs, or by hitiv 
no shell at all ; whilst in tin; Utter there is a wdl-drvdopM 
shell, into vhich th« animal can retire, and an operculum ii 
often present. 

Sub-class B. PuLMOxircRA or PtiLMOCAsrKRoroM.— t* 
this sub-class of the Gasttrvp«da rrs^rali»ti it atrial, and it 
c-trricd on by an inflection of the mantle, forming a ptUnonsf 
chamber, into which air is admitted by an cxlemal apeituA 
The fiexure I'/lAe intestine is nettra/, and the sexes arc united | 
in the same individual 




ncu>— £.MH(j;A«r#^, OHorihcSluci. (Ah««w«m>d.) 

The Pulmmi/tra include the ordinary land-snails, s' 
pond-snails, it, and arc uiualiy provided with a wcU-dewi -- 
shell, though this may be rudimentary (as in the slug^' 
e»-en wantins. Though forrnMl to breathe air directly, ni- 
of tlie naenibcrs of this sub<l««s are capable of inhabiraj 
fresh water. The common Pond-snails are good coamplr- ■' 
these last The condition of the shell varies eready. Sji 
such as the common I^nd-snails, have a well-developed sht.<, 
within which the animal can withdraw itself cootpletrl^ 
Others, such as the comn>on Slugs (fig. 113) have a rudini'r ' 
aijr shell, which is completely concealed within the man' 
OuKTsare entirely destitute of a sh«U. They are divided lUO 
two sections as follows -. — 

Stdifftt I. imfftculala^— Animal not prvHd^ with OM »!f- 
etilum t« doit Iht tMI. In f>^« v»:>;nq<ci u<l v'ocludcd the faaata 




hollusca: gasteropoda. 



317 



'tSdJa (l.ADd-siuiIs), Limadda (Slugs), One'uiiada, LimnaiJa 

Pood-snaib), and AuruulUa. 
'tttioM II. Op<rat!iUa. — SMtH ths(d by anofuraiium. lothis 
ioa arc included the families Cyei^ilimida and Adculida. 

SVlfOrul op TKR FAMI1J» op TItB GAITUOPODA. 
(APTUt WOODWAKIX) 

noN A. Bkanchipeba. R«>|>intion aquatic, by Ibe waUt of the 
maMfe-nvJiy, ot by bnuichiic 

<EK I. ftosoDiiA.scHiATA. Thc bmnchto: »tualcd (/nwn) in ad- 
¥aiii« or thc bout. 

fnimti uM « (Wm/. 
^•iM. I. SfrmmhJr. Shell u'llh kd expanded lip, dwply notched 

neat the cuiaL Operculum eUw-thipcd. Foot narrow, adiptod 

tea ttapln^ III. Gen. Sirvmiiu, fUrsctnt. 
/■!•>. I. Muritiia. Shell with a itniehl uilaior mnoJ, the ■pntOTe 

tniire poMerioily. Foot bread. IIL Gen. Mnrtx, Tium, I^rvla, 

ftuul. 
Fam. 3. BirentiU*. Shell notched Anrcriorly, or viih the Cdnal 

■tn«p(l]> relkcled, produdnj; ft kiiid ot rahi en thc front of the 

thell. III. Gon. BmdnHm, iVtuta, Parfnra, Catiii, Hatpt, 

F»m, 4. Ctnida, Shell iovFnelyconical.wilh a lonsnairow apcr- 
van, ike oiler tip tiotchcil al or am (he luturci Operculum 
tdinole^ lamellar. 111. Gen. Cttui, ISairit»ma. 

Aw. J. tWufiiir. Shell lurrelci] or convolute, the aptiture notched 
In html : the cohnuetli cililii|ii«lir plaited. No iq>ercu)uni. Kont 
v«tirUr|n; inaalk often rclle<ctM over tbdthtU. III. Gcs. Vtlulo, 
Mtttv, Atairpiutla, 

fitm. 6. Cy/r w U*. Shell c<m»olul<. enamelled i imre eoncealrf, 
apcdiue narrow, channelled it each end. Outer lip tliin in l}ic 
VMM; Aell, bol thickened and inllcctoj in Ihc aduk Fool 
eraad; maatle fbtminf lobes which inocl orer the back of the 
Acll. IIL Gen. Cffnra, Ontlum. 

lunkiid *r /■rvJmai inl* a tantil. 

Fam. I. X^iiiiLt, SbcUclobuTtr, alTew whorlt, withannallq)ii«i 
ODicr Up arule, pillar Mltri callous h'oni lery large 1 mantle* 
lobca hiding more or Icn of ihe khcll. Cen. iValiia, S^rWu. 

Kim. t. /ymmiMliJr, Shell turrcled, with a imull apcniue, 
MnKiine* with one or more pioniinoil plaiii on the tolumetla. 
ni<oculom homy, imbricaled. 111. Gen. r^ramiMla, CAimniM^ 

F»m. J. Cirithm^. Shell (pttat, hirreleil ; ajwrture channelled in 
front, with a In ditiind poMorlor canal, t.ipcenerallr cvpandol 
in ih« adulu Operculum homy and spiral. 111. GeiL CtrHiium, 
/\<tjmiJn. AfvrrAaii. 

film. 4. M/iamatlir. Shell ipiral, lurreted t aperture oRen cfaan- 
twIM or nolched in front ; outer lip scuie. Opcrculiun homy 
•Dd tpiraL 111. Cen. .t/iJmua, /Wudtmm, 



3l8 MANUAL OF ZOOLOGY. 

FaBi. J. Turrildlida. Shell tubular, or iraral, often tnnctel; 
upper part partitioned off; aperture simple. Opomlun bonTi 
many-whorled. Foot very itiort. Branchial plume lingle. IL 
Gen. Turritella, yirmitiu, Stalaria. 

Fam. 6. UUar'midic, Shell ipinl, top-tfaaped, or d tpiful ; ^o- 
lure rounded and entire ; operculoin homy and paud-ipinl, QL 
Gen. LiltormOy Solarium, Jfiaaa, P^ertu. 

Ftim. 7. Paludiaidit. Shell conical or globular * apeititn roEndid 
nnd entire ; operculum homy or shelly. 111. Ueo. /Wndu, 
AmpuUaria, talvaltt. 

Fam. 8. .\'iT//iifi<-. Shell thick, globular, with a veiy uaati iput; 
aperture semi-tunatc, its columellar tid« expanded ; oora lip 
acute. Ojierculum shelly, sub-spiral. 111. Gen. Xtrila, PMu, 
A'ttifiriii. 

Fam. 9. THrhiHida. Shell turbinated (top-shap«d), or j^iamidil, 
nacreous inside. Operculum homy and multi-spiral, or ali3' 
reous and jiauci-spiriu. Ill Gen. 7t»A>, Trtxkta, MfUimU, 
Eucmphalus. 

Fam. 10. HaliKliiLi. Shell spiral, ear-shaped, or tl«choid ; apntiK 
large, nacreous. Ouler tip notched or perforated. Nooperoilan. 
Manllc-mariiin with a poslerior (old or siphon, occup]iiae tlic ilil 
or perforation in the shell Melapodium rudimenlary. 111. G«b. 
Haliotii, Scisiur/lla, Pleuroiamaria, Mtmhisonia, laulhita, 

Fam. \\. Fissiirdlidit. Shell conical, patelllfonn, with a DMch ID 
Ihe an lericir margin, or a perforalion at ils apci, which ii ocoiFiol 
by an inal siphon. Muscular impression horse-shoe-shaped, opes 
ill front. III. Gen. Fisiurdla, Emurginula, Fiirmopksrui. 

Fam. 12. Ciilyflricijie. Shell palellifonn, with a more or leu S[nnl 
apex ; interior »im])le, or divided by a shelly process to which tbi 
adductor muscles are attached. III. Gen. Cafyplr-ia, Pderpm. 

Fam. I J. J'MdliJte. Shell conical, with Ihe apex turned fomr^; 
muscubr impression horse -shoe-shaped, open in front. Foau 
large us the maigin of the mantle. Kespiratory organ in the fan 
or one or [wo branchial plumes, lodged in a cervicaJ cavity: «i' 
a series of lamelli surrounding the animal between the boJy inJ 
the mantle. 111. Gen. PaliUa, Acmaa. 

Film. 14- Dtiilaliiii!-. Shell tubular, symmetrical, curved, opoi >: 
l>olh ends. Aperture circular, foot pointed, with symnetiial 
side-Iobfs. (.Jen. Dtalalium.' 

Fjm. 15. Ciilonidc. Shell mullivalve, composed of eight Itansr* 
imbricated ]i1ales. Animal with btoad creeping foot ; bnmduf 
forming a scries of lamella: between the foot and the mulk 
round the posterior part of the body. 111. Gen. CAHvn, Cfy^ 
eiiliiH. 

Order II. OpisTUonRASCHiATA. Branchiae placed towardx the roi 
(•'/ijtifii) of the body. 
S^-tioii a. TttlibraHchiala. Bratukit taitred by lit sMell tr maaHl .' 
a shAi ill iTit^st. Sfxfs umffd. 
Fam. I. TetiiaulliJic. Shell extcmal, spiral, ot convoluted; tja- 
ture long and narrow ; columella plaited. lU. Cicn. TiviufAt). 
CiiiuUti. 



* Dtnlalium is plnce<! by Professor ! luiley amongst the Fltrtffiia, ftw 
its rudimentary head, the neural flexure of the inlesUne, the nature of Uu 
epipoJia, and the ttiaTtt«M5 0t<,\ie\»n3_ 



HOLLUSCA: GASTEROPODA. 



319 



Ptm. 1. Siilr.t.r, Shell ciMivuluIcil, Itiin ; spirt *bM or Mncniot, 

lip tharp. Animal more or les iiivtsiiiii; ilw ilidl. Ill Ocn. 

AMi, CWiiiHjt, J'liilifV. 
J'tim. 3. AftjmaJ^. Shell «1iwnt, or nidimenlanr and concealed 

by mt muul& Aninial i)ue-likc, wi:li «xleniivc lidc-lobe^ 

(epiiiodii), rcdecttd ovu the tuck and thcll. III. Ucn. Aftrtia, 

DfUMti. 
Fam. 4. /tturfimmhiJ^. Shell palclliform, or c«ncMle<l> nrclr 

waniiac. Manlle or ithrll i-ovcnns (he back of the animal. 111. 

Gen. /VrurvtrviKiiai, UmUtlLt, 'Pfiiiiiiia. 
/jw. y pktlliJiad^. Aniniol ihell'lcu, coTcrcd by a mantle. HI. 

Geu. ItyiiaM, DifJtyJJiJia. 

Sulim i. A'iiJitr«mii«ta. AifiamtJfilitiileffiisMliiilitaJiilitwi- 
dilifa. BnmAtr txliriiat, em l!u taci er liiia t^ltu tedy. 
/■'am. & DfrKtr. IIL Gen. l>tri$. 
Aam. 7. Tri/MinJ.r. 111. Gen. Trifmia, SrjrtLm. 
Jhm. S. jetliia. IIL Gen. yF.,'ia, G/aiuui. 
/iim. 9. rkyllrrk.'iit. Gen. I'hytiirkat. 
Fam. 10. aiyuada. III. lien. fjyiU, AiUtmiA. 

till. NucLix>IiliANCHI,(rA or ItRTEKDPOIM. Shell pTeKiit OT 
abwnL Animal frec-icimniiiig and pclogiiv with a fin'lltta uil. 
or \ iMIcned ventnl Gn. 

Fmm. I. FiroMt. Bodf Iotbc i hnnchi* ^xhmI on the back, or 
cevefcd \f ■ tmoll h^lne iheli ; locomolian b}' meani of a ven* 
inl fia UM a ulUfin. III. Ocn. CAriaoria, Fiivti. 

F*m. I. AHantU*. Animal ritnUhed vith a well-detelc^ed iheP 
into whkfa k OB reiirr. Hntnchl* eonialned In a iloraJ mantle- 
ivUjr. Shell tjriBmtlrial, diicuidal, Mmetimta wlib an opcr- 
IIL GcD. AUaiUa, BiUenfiliaa, Mattkrtm. 

WN II. Plf uiOHinRA. RMpintion acriil, by meant ot a pulmoniuy 

ckaoiUt. 
iJlvixtoN I. IxoTKacvLATA.. SMI Htt frvi'ideJ vitik an itfertufHiK. 

Kim. I. Uriieidit. Sliell cxlcmal, capable of oontainin^ ihe whole 

antmaL III. (icn. Hrlix, BttSmtu, CiamtUa, fnfo. 
F»m. ±. Llmaiitit. Shell ndimentaiy, luually internal ot ^^t'y 

ooMOtled by the mantle. IIL U«xi. Limax, /^mutitlli, Tata- 

an*. 
Fkm. J. Om-iduJa. Shdl wanting. Animal slug'like. III. Gen. 

OmitJHim. fftfima/iu. 
Fam. 4. ZmnMnbr. Shell thin, horn-coloured, irell deneloptd. 

Apcrtaie limply lip thaip. III. Gen. Unmaa, Phyia, Amyliu, 

FUiurht. 
Ftnt. $. Auritutiif. Shell ipiral.wlt1ia1iomyepiderml>i aperwre 

cJonigMed. ■kellculaied. 111. (i«n. AurityM, Ciuu^-uIju. 

ItvitiQN II. OHact<i.ATA. SM/irilA OH ^rttUmm. 
Fam, 6. CyrhtiemiJ*. Shell ipital, rarely elongated, often At^ 

preued. .\p«tu>e nearly circuW. Operculum vfiitX. III. Gen. 

CftkMtma, CwUfkariit, I'hptif*. 
fitm. 7. ArifiMit. Shell rlcin|[a»d, crliodrieal ; operculum Ibio, 

ud nb-iplnU. Gen. A1K11/.1, CtinniUiiia. 



320 



MANUAL OF ZOOLOGY. 



CHAPTER XLIX. 

PTERQPODA. 

Class III. Pteropoda. — The i^fri^^n are defined by bent 
free and pelagic, swimming by means of two wing-like appto- 
dages (epipodia), developed from each side of the anteni 
extremity of the body. The flexure of the intestine is neuiiL 
As to the position of the Pteropoda in the Molluscan scale, 
they must be looked upon as inferior in organisation to uyii 
the Gasteropoda, of which class they are often regarded ai tbc 
lowest division. They permanently represent, in fact, the WD- 
sient larval stage of the sea-snails. 




FLjE. IE J. — PtcropodA. a Clffldflm frmmufata: h Ctivitrut ettummUM. 

(After Waodttud.) 

The Pteropods are all of small size, and are found swiffl- 
ming at the surface of the open ocean, often in enormous 
numbers. Locomotion is effected by two wing-like fins, dad' 
oped from the sides of the head, and composed of the grotlj 
developed "epipodia." The true "foot" is rudimenlar)- aai 
rarely distinct, but the " metapodium " is sometimes proiidoi 
with an operculum. There is usually a symmetrical gbs>7 
shell (fig. 114), either consisting of a dorsal and ventral plJ^ 
united, or forming a spiral, but in some cases the body's 
naked. The head is rudimentary, and bears the mouth, whid 
is occasionally tentaculate, and which is furnished »itb «" 
odontophore. There is a muscular stomach and a wdlnievd- 
oped liver ; and the flexure of the intestine is neural, so tbt 
the anus is situated on the ventral surface of the body. 

The heart consists of an auricle and ventricle. The re^ 
ratory organ is very rudimentary, and consists of a ciliaira 
surface, which is either entirely unprotected, or may be «!"■ 
tained in a branchial chamber. 

The ganglia ot the neDOMs s-jstcm " are concentrated inw 




MOLLUSCA: PTEROPODA. 



mass fielflw the cesopbasua " (WoodwaxJ), and the eyes aie 
idimcntuy. 

The icKvs nic united in all the Pteropods, and the young 
in through a nKUmoiphosis, having at liist a bilobed dliaied 
Bil attached to the sides of the head. 

Plic PUr^eda are divided into two orders, termed TTittoio- 
r and Gymiwsomata ; the former charactenxed by posscss- 
tn external shell and an indkiiiict head ; the latter by 
eing devoid of a :Uiell, and by having a distinct head, with 

»ittiiche<l «> the neck, 
he Ileri'poJa, ,-ii already satd, are found swimming near 
M urfacc in the open occ^n, and they are found in all seas 
wm (he tropics to within the arctic circle, sometimes in such 
unbcrs *s to discolour the water for many miles. They are 
Dttanul in tbdr habits, and, minute as they are, they con- 
titnc in high latitudes one of the staple articles of <liet of 
He whale. They themselves are, in turn, jtrobably ciimivor- 
tM, feeding ujton small Crustaceans and other diminutive 
nimU*, 'J'hough all the living forms arc small, Ucology leads 
» 10 believe that there fonncrly existed comparatively gigantic 

ficQtatives of this class of the MoilmM. 
Svxorau or thk Familiis op thk PTUtoyopA. 
{AfTEa WoODWAKUt) 
1 L Tmicdsomata. 
AtioHd <dlh kn cilcrnal shell : heftd IndittJncl ; foot and leo- 
txhi radliBcciluy ; mouih liiuaied In « tnriiy fonned by the union 
ti tha iDcomoliTS or|,-aiii. Kctpintoty or)[>M mntiined wiihin a 
manih-cBTiiT. 

rn. I. llyaMt. 
Shell (]riBnielri(«l. clnifihl or curved, clobntar or needle- »hiped. 
in. G<«. ffyalfx. Ctmhnt, Tina, C-mUari^. 
Am. 3^ UmofinU*. 

tSbiM minute, (pbal. wmctlme* opcicul&te. HL Gen. UmaeiiM, 
II, GVMKOtOMATA. 

AbIouI naked, wiihoat atomic or thclt ; head dUlinel : f>n« sl- 
tadied to Ibc lidc* of the neck ( cill rndUlincl. 

Am. 3. am*. 

Body IWfens, foot distinct, <rith « e«nu»l and poaterior lobe ; 




322 MANUAL OF ZOOLOGY. 

CHAPTER L. 

CEPHALOPODA, 

Class IV. Cephalopoda, — The m«nben of this dui ne 
defined by the possession of eight or more anus placed m t 
circle round the mouth ; the body is enclosed in a mtucnlu 
mantle-sac, and there are two or four plume-like gilla wilhia 
the mantle. There is an anterior tubular orifice (the "infin- 
dibulum " or " funnel "), through which the effete water of re- 
spiration is expelled. The flexure of the intestine is neural 

The Cephalopoda, comprising the Cuttle-fishes, Squidi^ 
Pearly Nautilus, &c., constitute the most highly organiMd <i 
the classes of the MoUusca. They are all marine and cututo- 
rous, and are possessed of considerable locomotive powers. Al 
the bottom of the sea they can walk about, head downmnH 
by means of the arms which surround the mouth, and whict 
are usually provided with numerous suckers or "acetibuU.' 
They are also enabled to swim, partly by means of lateni 
expansions of the integument or tins (not always present), imi 
partly by means of the forcible expulsion of water through tte 
tubular "funnel," the reaction of which causes the animal to 
move in the opposite direction. 

The majority of the living Cephalopods are naked, posses- 
ing only an internal skeleton, and this often a nidimentaiy one; 
but the Aigonaut (Paper Nautilus), and the Pearly Nautilu, 
are protected with an external shell, though the nature of ili 
is extremely different in the two forms. 

The integument in the Cuttle-fishes is provided wth nfflW- 
TOus little sacs, containing pigment -granules of different coloov 
and termed " cliromatophores." By means of these tnaif 
species can change their colours rapidly, tinder irritatioQ* 
excitement. 

The body in the Cephalopoda is symmetrical, and is endostd 
in an integument which may be regarded as a modifiaW 
of the mantle of the other Molltiscit. Ordinarily there ii » 
tolerably distinct separation of the body into an antoiw 
cephalic portion (/>rosom:i), and a posterior portion, enrtlojjd 
in the mantle, and containing the viscera {mc/asoma). Tl" 
head is very distinct, bearing a \mt of large globular eyes, »d 
having the mouth in its centre. The mouth is surroiuMld 
by a circle of eight, ten, or more, long muscular processes,* 
"arms"(fi|:;. 115), which are generally providetl with rows rf 
suckers. l;.ach sucVa, ot " a.i'iVa.W.iiva," consists of a cuff 



MOLLUSCA: CEPHAl/)PODA. 



333 



cavity, the musctilar fibres of which converge to the 
^ where there is a little muscular eminence or papillii. 
f the sucker is applied to 
' tace, the contraction of the 
ig muscular fibres depresses 
.pilla »o as to produce a 
below it, and in this wajr 
ker acts most eRiciently 
adhesive omn. In some 
{Uua/fida) the base of the 
or piston, is sunx>iinded 
deatated ring, and in 
(«3 in OnjKAoteutitit) 
arc produced into 
In the Octopod 
there are only eit(ht 
and these are all nearly 
In the Pecapod Cutile- 
there are ten arrnK, but 
these— called "tentacles" 
mticb longer than the 
and bear sucketa only at 
dtremities, which are en- 
and club-itlu|>ed. In the 

NauiiltM the arms are nc. nj. — OphaiopodL sitittt 
low, and are devoid of t^^tiSTJ^'^'^^ 
ts. 

e arms are really produced by an extension of the mar- 
tf the " fool,"' or of the part cotrcsponding to the foot of 
Ihcr M»Utttta. The ■' artcro-laicral parts of each side of 
lOt extend forwards beyond the head, unitinf; with it and 
me another ; so tliat, at length, the mouth, from having 
■i(uate<t, us luual, above the anterior mar^Hn of the foot, 
I to Iw placed in the micUt of it. The two epipotlia, on 
llier hand, unite posteriorly above the fool, and where they 
ce, give rue either to a folded muscular expansion, the 
of which are simply in apposition, as in the Mautilus; 
WR elongated flexible tube, the apex of which projects 
id the maisin of the mantle, called the 'funnel,' or 
iditntlum,' as in the dtbranchiate Cffikalop^a." — 

■) 

mouth leads into a buccal cavity, containinf; tvro 
jI, homy, or (uulially calcareous mandibles, working 
ly like the beak of a bird ; together with an " oclotito- 
or " too^c^" the anterior part of which u Kn\iiinV, 





324 MANUAL OF ZOOLOGY. 

whilst the remainder is covered with recurred spines. Hie 
buccal caviiy conducts by an cesophagus — into which aalini7 
glands usually pour their secretion — to a stomach, from wbith 
an intestine is continued, with a neural flexure, to open on the 
ventral surface of the animal at the base of the funnel fa 
many cases there is also a special gland, called the "ink^b^' 
for the secretion of an inky fluid, which the animal dischugci 
into the water, so as to enable it to escape when menaced o 
pursued. The duct of the ink-bag opens at the base of de 
funnel ; but this apparatus is entirely wanting in the TeO* 
branchiate Cephalopods, where, in consequence of the pracsct 
of an external shell, this means of defence is not needed. 

The respiratory organs are in the form of two or four pjonw- 
like gills, placed on the sides of the body in a branchial cantf 
which opens anteriorly on the under surface of the body. JU 
the base of each gill, in the Cuttle-fishes, is a special contnE- 
tile cavity, whereby the venous blood returned from tin 
body is driven through the branchix. In addition to thee 
accessory organs — the so-called "branchial hearts" — there ii 
a true systemic heart, by which the aerated blood received 
from the gills is propelled through the body. In the high? 
Cephalopods a capillary system of vessels intervenes, in most 
cases at any rate, between the arteries and the veins, 11* 
admission of water to the branchise is effected by the expansicii 
of the mantle so as to allow the entrance ofthe outer n-ater into 
the pallial chamber. The mantle then contracts, and thenW 
is forcibly expelled through the funnel, which is provided 
with a valve permitting the egress of water, but preventii^ 
its ingress. Hy a repetition of this process, not only is respi- 
ration effected, but locomotion is simultaneously subser^-ol; 
the jets of water expelled from the funnel, by their reaction 
driving the anima) in the opposite direction. 

The nervous system is formed upon essentially the ss* 
plan as in the other Mollusca, but it is more concentrated, 
and the supra-cesojihageal or cerebral ganglia are protected bf 
a cartilage, which is to be regarded as a rudimentary cianiuft 
This structure, therefore, presents us with the nearest »p- 
proach which we have yet met with to the Vertebrate type i 
organisation. 

The sexes in all the Cephalopoda are in different individmlii 
and the reproductive process in the Dibranchiate section of 
the class (Cuttle-fishes) is attended with some very singulu 
phenomena. In this order the ducts of the generative organs 
open into the pallial chamber, and each individual, beside 
the essenliaY oxgalls ot leptoiat'ttou (jestis or ovaiy), ge«- 



MOLLVSCA: CEPHALOPODA. 395 

Sj poMCSses an nccetsoir ^nd ; that of the fcmslc secret- 
ig a viccid material which unites the eggs together, whilst 
lat of the male coals the spermatozoa, and aggregates them 
ito peculiar worm-hke filaments, termed " spemialophorcs," 
r the " moving hbn>cnts or Needham." The spennatophore 

filled with &pennuto;(oa, and potseiueii the power of ex- 
inding when moistened, ruptiitJng, and ex|>elliiig the con- 
ined spermaKuoa with <:on:(i()crat>lc forte. During the 
mgress of the sexes the male transfers the spermatophorcs to 
le p*llial <:hamber of the female, tnie intromission not being 
NsiUc. Kurlher, in all the male Cuttle-lishes one of the 
9u is specially modilicd to subserve repradiiction ; being 
. manf cases so altcie<l as to become useless as a loconiolive 
'gan. The arm so alTected. in the more striking forms, ts 
jd lo be " heciocolytbed," and — like tlie metamorphosed 
iipi of the male spiders — it serves to convey the seminal 
uid to the female. '1'he mode in which this is eifecled varies 
t tJiflercnt species. Thus, in the mate 0//o/>ut (the Poulpc) 
IT third right arm is primitively developed in cyst, which 
Umalely ruptures and liberates the metamorphosed arm, 
Uch then a]>peart 10 be of jp'eaier sii.e than ilic correspond- 
Ig arm on the left siile, and to terminate in an oval plate 
ie> )t6). To this terminal pl.itc the S|>cnnal0phore is prO' 
■biy tiansmittetl, but the arm itself probably remains pcrma- 
cnily Attached to the animal. It is asserted, hon-cver, that 
n the form figured below ((!AlI^wr /irrfThi) the hcctocotyliscd 
nn is dciach«l and dc|)osited in ihc palllal chamber of the 
emale ; being reproduced after each generative act. In 7>r- 
ntU^ the tliird right arm of the male is " hectocotyli^cd." 
ad IS converted into a vermiform body, with two rows of 
tiHnd suckers, and an oval appcnda^ or sac behind, which 
nottiBi ■]>cnnatozoa. Dcsidcs the xndters, the anterior part 
If the luck ia fringed with a number of so<allcd "branchial" 
iluncntt. 

In the Argonaut the male is not more than an inch in length, 
* devoid of 3 shell, and has its third left arm hcclurolyliM:d. 
rUs arm is developed in a cyst, which is rupturc<l by Ihe 
Bovcmenia of the " hectocotylus," which ilicn appears as n 
BuQ worm-like body, with a filiform appendage in front, with 
m rows of alternating siicken, and a dorsal sac with ntime- 
au "dtromaiophores." 'I'hc duct of the testis probably opens 
MO the base of the hcctocotylu^ whi<:h is ultim.Mely detached, 
od ii deposited by the male within the pallifll >:haiiilier of the 
onalc. when tir\t discovered in this position, it w.i-i descrilvcd 
sitic worm under the name of " Hccloc<A>-\vis ■," »^ 



•^Dspsiuc iroa 



326 MANUAL OF ZOOLOGY. 

sequently it was described as the entire male, ind k it onlf 
recently that its true nature has been fuUy ascettained. 




Fig, 116.— I, OctofMi otrtnA {m^\ ihowmK cyst in place of (he third iTA ^'^ 
tral side dT an individuali mon developed, with the hcctocotylui 1^ ^ 
Woodvanl.} 

The shell of the Cephalopoda is sometimes external, sen*- I 
times internal. The internal skeleton is Itnown as the "cnt^ I 
bone," " sepiostaire," or " pen " {gladius), and may be ti^ 
corneous or calcareous. Id some cases it is rendered complQ 
by the addition of a chambered portion or " phragraaaW," 
which is to be regarded as a visceral skeleton or " splaiid0>' 
skeleton." In Spirilla the phragmacone is the sole intoiBl 
skeleton, and is coiled into a spiral, the coils of which lie i> 
one plane, and are near one another, but not in contact It 
thus resembles the sJiell of the Pearly Nautilus, but it is inltrtiA 
and differs, (hercfort, entirely from the external shell of At 
latter. The only living Cephaloiwds which are provided •ill' 
an external shell are the Paper Nautilus (Argonauta), anddw 
Pearly Nautilus l^Naulilus fomjilius^ ■, Xja-oka. ciftlx is the stnt 




MOLLUSCA: CEPHALOPODA. 



327 



' animal diffemit in each of these, bat the nalarc of 
: (hell itself is entirely difTcrcnt. 'Hie shell of Ihc Argonaut 
117) is involuted, but is not divided into chambers, and 
it Kcreted by the webbed extremities of two of the dorsal 
as of tl)e female. The arms ate lient ttackward*, so as to 
the aniinal to live in the shell, but there is in reality no 
aic connection between ihc shell and the Iwity of the 
In fa^^I, the «hcll of the Argonaut, being confined to 
female, and serving by its empty apex as a receptacle for 
ora, mar be looked upon a.s a " nidamcntal shell," or as 
ia secreted by a modified portion of the foot, it may more 
gropefiy be regarded as a ■* jiedal shelL' The sliell of the 
Peajly Nautilus (fig. 119), on the other hand, is a true pallial 
>h^i, and is secrieted by the bo<ly of the animal, to which it is 
organically connected. It is involuted, bill it dilTeTs from the 
shell of the Argonaut in being divided into a series of chambers 
by shelly paitiiions or septa. whicJi arc pierced by a lube or 
" siuhtinclc," the anioul itself living in the last chamber only 
of the shclL 

The Ophalt^a arc divided into two extremely distinct and 
"cll-mirlced orders, termed tlie Dih-itmhiala and the Tdra- 
^tidti%Ua. lite former is characterised liy the posscKsion of 
(wo branchtiB only, and comjiri.ici the C^ittle-fishes, Squids, 
*r»<J the P;ij>er Naiutthu. The latter is dislinguished by the 
P'eiCTce of four gills, and, though abiind-intly represenietl in 
C^m time, has no other living representative than the Pearly 
Haublitt alooc. 




CHAPTER LI. 

DIVISIONS OF THE CEPHALOPODA. 

'itDESt I. DiBRAMCHiATA. — The members of this order of the 
are characterised as being swimming animals, al- 
toofit invariably naked, witli never more than eight or ten arms, 
khich arc always provi<led with mclccrs. There are two 
btancbiin, which are rumishctl with bnmrhial hearts; an ink- 
■^c is always present ; the funnel is a complete tube, and the 
^Bu;ll >s internal, or, if cxlcmal. is not chambered. 
^F'rhe Cuttlc-6ihei are rapacious and active animals, swim- 
^Bung freely by means of the jet of water expelled from the 
' ^mod. The arms constitute powerful oftenuvc vcaLVOri-b, 



tnts section are distinguis: 




^^'i*""' "1" r'"'*' ■""'"" "™ii 
p™«I^»™ .he A.U. .hid, ;h,y^ 




hollusca: cephalopoda. 

d in the subsi:incc of the mantle.— (Ovreo.) 
loro provided with lateral 
te third tight arm of llie male 
"Y <)eveloi>ed in a cyst, and 
becomes " heeiocotyliscd. " 
R Dkcafoda.— liie t'c- 
Is of this section have eight 
I two additional " tentacles," 
^ much longer than the true 
retractile, and have expand- 
.|)ed extremities (fig. 115). 
are pedunculated; the 
,ys provided with lateral 
the shell is always inicm.il. 
^tion comprises the three 
Inilies of the Tfvlhida, Stpi- 
IthciyxV/t//^/*?, and the extinct 
flbe BfitmniiUa. 
toiily of ilw Tetilhi4a com- 
ic Calamariet or Sijuidt, cha- 
5 by the possession of an 
1>ody nith lateral fins. 
fis internal and horny, con- 
a median shaft and of two 
inga ; it ia termed the " ([ladi- 
pwn," and in old s[)edtnens 
{Bay be found lodged in the 
one behind (he other. In 
Ition Calamary {Lelig«) the 
|t arm of the male is mcia- 
ed towards Its cxircmi^ to 
[reproduction. 

) family of the Sepiadie the 
l^lt b calcareous ("cuttle- 
I " lepiostaire "), and is in 
mf A broad plate, having an 
py dumbercd apex, 'i'hc 
Buinatcd plate is extremely 
[spongy, and the chambered 
nllcd the "mucTo." in the 
^bcrs of the family the body 
Id with long lateral Jtns, sometimes as long and as wide 
lly itself. 

kin^lar family of the Spimhdir ihc internal skeleton is 
"- of a luucvuf, discoidal shell, the whoiU ol "w\wt^ 



1\t, ■■& — Dlipui df Mew 
niie WIci lIvloBr t^Ulvd. 
r H«nx pm « ~p»»««i»- 
oin i * / Clwinlwcd "fihnc- 
macoM ia lU caviiy ba) (r 
" *t««>i1ut ," t~ Cuird. 




330 



MANUAL OF ZOOUJGV. 



arc not m contnct with one another, and which is dividi 
a series of clumbers by mcttos of iiaituioiw oi »cpu wl 
pierced by u ventral lube or" si[Aunde." The body is 
with ininucc terminal fins, and the arms have six rows of 
KUckeri. 'I'he shell of the .^VWa— ^^omnionly known 
" po«l-hom " — is similar in .tuucturc to ihff shell of the 
lus, but it is lodged in the ixjsterior part of the body of tlic 
animal, and is therefore internal, whereas the &hcU of Ibt 
latter is extemai. It really corresponds to die " phrBpaacooe" 
of the Bcleinnite. Though the shell occurs in enornunu IWB- 
bcrs in certain localities, a single perfect specimen of the annnJ 
is all that has been hitherto obtained. 

In the extinct family of the Btlemnilida^ our kxMiwIedge i* 
chiefly oonitncd to t)ic hanl [>arts. Certain spccinMMts, bo>- 
ever, have been discovered which show that the Btiemmte ktd 
essentially the structure of a Cuitlc^sh, such as the rccmt 
Sffia. The body was provided with lateral fins ; tlvc anm 
were eight, famished with homy hoolts, with two "tenl«ei«i" 
and probably the mouth was provided with honiy mandibln 
An ink-bag was present. The internal skeleton of a Bt^ 
niu{fig. ti8) consists of a chambered cone — U)e "phragnu- 
cone " — the septa of which are pierced with a marsioal tube 
or " siphuncle." In the laat chamber of the pbragmaconc it 
contained the ink-bag, often in a u-eJl-prescrved conditioa 
Anteriorly the phragmacone is continued into a horny lamiia 
or " pen " {the " pro-oslracum " of Huxle)-), an<! [Mkicrioriy it 
is lodged in a conical sheath or "alveolus," which is esicaiiKil 
in the siibttance of a nearly cylindrical, 6t>rotis body, ik 
"guard" (tig. ii8,;). which projects backwards for a kxigtr 
or shorter distanoc, and is the part most usually found in i 
fossil condition. 

Ordkr II. Tetrabranchiata. — ^Thc members ofthisords 
of the CffhaU^ila arc characterised by bcinj{ creeping aniash 
pn>tectcd by an external, many-chambered shdl, the sepB 
between the chamber) of which are perforated by ■ menln 
nous or calcareous lube, termed the " siphuncle:" The laH 
ore numerous, and are devoid of suckers ; the branchia m 
four in number, two on each side of the body ; the funnd dos 
not form a complete tube ; and there is no ink-bag. 

Though abundantly represented by many and varied eaiW 
forms, the only living member of the Tetrislvii/tMiiM it dx 
Pearly Nautilus, which lias been long known by its bcMtiM 
chambered shell, but the soft parts of whidi can hordty be sbJ 
to be known by more than one perfect specimen, vhidi «P 
exanuDcd by I'lutcuut Qw^^ 




I 



MOLLUSCA : CKPIIALOPODA. 



331 



The soft stnictures in ihc Pmrly Nautilus may be divided 
into a poitcrior, soft, membranous nuM (mf/MouM), contnin- 
inj; t)ie viMTcra, and an anieriw muscular divisinn, compiisiDg 
(he hcail {pratDma); the vrhole being contained in the outer- 
most, ca[KidouK chLfimbc-r (the body-chamber) of the shell, from 
which the head cm be piomided at will. The shell itself {tig. 
1 19) is involuted and many-chambcied, the animal being con- 
tained successively in each chamber, and rctirin(; from it as tti 
iiz« becODKS snfBciently great to necessitate tht; aciiuisition of 
more room. Eadi chamber, as the animal retires from it, is 
walled off by a curved, nacreou* septum ; the communication 
between the chambers being still kept up by a membranous 




, if&-Pluf|rKmuav>(.%'»ri7>i*-w/Mnt). a Uinik ; » lu doruT fold ; 



tube or siphuncte, which opens at one extremity into the i>eri- 
cvdium, and is continued throu(;h tlic entire length of the 
shell. The position of the (iphuncle is in the centre of each 
•cptunt. 

FtnterioHy the mantle of the Nantihts is very thin, but it is 
much thicker in front, and fonns a thick fold or collar sur- 
rounding the head and its B|>pendBgcs. From the sides of the 
head (pring a ^cat number of muscular prehensile processes 
or "uim," which are annulated, but arc not provided with 
eups or suckers. In the centre of the head b i)ie mouth, sui^ 
rounded by a circular Hesliy lip, external to which ii a secies 
tfUbbl processes The niouiii opens into a buccal camic}, 




332 MANUAL OF ZOOLOGY. 

armed with two homy mandibles, partially caldficd tonidi 
their extremities, and shaped like the beak oT a pamt^ a- 
cept that the under mandible is the longest. There ii 
also a " tongue," which is fleshy and sentient in fnm^ hst ii 
armed witfi recurved teeth behind. The gullet opens intoa 
lai^e crop, which in turn conducts to a gizzard, and the intes- 
tine terminates at the base of the funnel On each side of die 
crop is a well-developed liver. 

The heart is contained in a large cavity, divided into seven! 
chambers, and termed the "pericardium." — (Owen.) The re- 
spiratory organs are in the form of four pyramidal bianchiz, 
two on each side. 

The chief masses of the nervous system are the cerebral ud 
infra-oesophageal ganglia, which are partially protected by i 
cartilaginous plate, which is to be re^rded as a rudimenujy 
cranium, and which sends out processes for the attachment of 
muscles. The organs of sense are two large eyes, attached 
by short stalks to the sides of the head, and two boilo* 
plicated subocular processes, believed to be ollactoiy in tber 
function. 

The reproductive organs of the female consist of an oviij, 
oviduct, and accessory nidamental gland. 

There is no ink-bag, and the funnel does not form a ccm- 
plete tube, but consists of two muscular lobes, which are sim^j 
in apposition. It is the organ by which swimming is effected, 
the animal being propelled through the water by means of the 
reaction produced by the successive jets emitted from the 
funnel. The function of the chambers of the shell appeas 
to be that of reducing the specific gravity of the animal to nes 
that of the surrounding water, since they are most probaWf 
filled with some gas secreted by the animal. The function of 
the siphuncJe is unknown, except in so far as it doubtless semt 
to maintain the vitality of the shell. 

Shell of the Tr.rRABRAtJCHiATA. — The shells of all the 
Tftrabraw/iialii agree in the following points : — 

1. The shell is external. 

2. The shell is divided into a series of chambers by plaits 
or " septa," the edges of which, where they appear on the sheD, 
are termed the "sutures." 

3. The outermost chamber of the shell is the largest, and is 
the one inhabited by the animal. 

4. The various chambers of the shell are united by a tube, 
termed the "siphuncle." 

Agreeing in all these fundamental points of structure, tw) 
very distinct types of shell may be distinguished as character- 




MOLLUSCA : CEPHAIX>PODA. 

r the two families NautUiJa and AmmMtili^, into which 
rder Titrabranehiata ix clivi<l(.i]. 

I the family Nautilida (% i za), the " septa " of th« shcl) 
bnpic, curved, or slightly lobcd ; the "sutures" are more 

tcomplelelx plain; and the "siphunclc" is central, 
si, or internal \i.e., on the ivfWtnvside of the curved 

»)■ 

I the faniiljr Ammmilida (fig. no), on the ether hand, th« 

[arc folded and complex ; the sulurex are Angxilaled, ■i\%- 
|pl>ed, or fbliaccout ; and the nphuncle is cxurnal (i./., on 
)itvtx tide of the cunnl shells). 

1.0 .0 O'Q,0 




IIA— Dujpw toilluttnla ih* inuifnn af iKa afphaKlD and thAfAmofih* tepu 
W'i'niB 'I III il< Ml hi in CcvhUApodjL ITi* upp«r nr* of l^iipn rvprrMvet 
■iiuBi kcciiiHa af 1)>c illciu, ibt lo*-?f mr npnftcnU (>i« Algc* uf Lhd ■'F'^ 
F,< ■— mW m BtnUtii tt Crmtttt: it Cmuuitr; dd C<riiw'M> ,- f / .Unir- 

Iiboth these great /v/w of shell, a teries of rq>rcseiitative 
[ exists. Tcwmbling each other in the manner in which the 
lis folded or coiled, but difTcring in their fumbmenial 
(urc. All these different forms may be looked upon as 
kc«d by the modificaiion of a greatly elongated cone, the 
hire of which may be in conformily with tlie tyjic either 
fc SautUida or of the Ammanitida. The following table 
ji Woodward) exhibits the representative forms in the tO'O 

straigtil .... Onhoceras . . Baculites. 

tbent on itself . . Ascoceras . . Ptj-choceras. 

car«-ed .... Cynoccras . , Toxocenis. 

k sniral Trochoceras Turriliies. 

if dtscoidat .... G^-rocenu . . Crioceras. 

L dtKoidalandptoduced Lituites . . . Ancylocerat. 

M involute .... Nautilus . . Ammonites. 

irr the Xm/i/iu itself, the most imfiorlant fonrn of the 
%tuiit is the OrtAMtrat{6^ lai). In structure this n'as 



334 



MANUAL OF ZOOLOGY. 



doubtless essentlilly identical irilh th« KxutiluB, but the (beU. 
instead of being coiled into a spiral lying in one plane, ns a- 1 
ten<leil in a straiKlii, or nearly straight, line Ortboccnbtesof j 
moiv thiin mx feet in length have been di»covered. but in ti, | 
the bocly-diamber, in which lite animal was lodged, appeanU 
haw tiL-cn corapanklivcly small. The siphuncle is usually rof I 
complex in structure, and vras calcareous throughout its tatiff 
leqgth. 




thcvpIL s, Tnuiinr<nckAA)Hiori}ieWQC. *h4wvii(f) tbc iiiAndc^ 

The Structure of the shell in the AmmcNituhs is sadly thtl 
of the Pearly Nai\tilu», ronxistinj; of an outer poiceUuuat . 
and an inner nacreous layer. The body-chamber was mher 
elongated than laterally expanded or dilated. The sin>{fat 
form of the AmmwitiJa is the BaatlUt, in which the (Ml i> 
suaiglil, like that of an Ori/itxtras, whilit the scjua Iwve ll« 
characters of those of an Ammcmlt, Ind the sipjiunde is o- 1 
tenal. In the Turriiiu the structure of the shell is the ntK i 
but it \•^ coiled into a ttirreceit sjiiral. In the AmmwaU lUdL 
the shell is dii^coidal .nnd invohiied. corresponding ('m/trm)\t \ 
ihc iihcll of the Naulilut ; the body-chamber «as of cooqat* 
lively Urge size, and had its apcrtuic closed, in somc-epcoct 
at any rate, by an operculum. The shell mmctimes atuiix^ 
a gigantic size, and so-cral hundred species of the genus hnt 
been described. In Crmtrat the shell was a flat sptnl, Sh 
tlut of ihe .\niinoiiiies, but the whorb are not in contact. '• 
Toxocerxis llie shell i.i shaped like a bow. In Atteykarai^ 
Nhell is at ftrit dlscoiihtl, with sqarate whoib, then prodnJ 
into a straight tine, and finally bent forwards into a hook. 

Svxonit or rMK FAUiLtES of thr CsPiiALoroixc 
Q\jA% CKriiALorobA. 
lL DiBRA\-ci[t\r«. 

Aiiiiniil wiih Iwo InnActiiJEi oat marv Ihaa tji^bl orli*^^ 
pr«ni<liN|ii'iih tixkcn; on ink-faac: iJicIl c«mnMily uMOll*' 
mdiinciilar; i racely atenul, but not tbunbsnd. 
SeCTIOKA. OcT«iv>l>*. 

Amu n£U, xmVax Kiufa. 



MOLX.VSCA: CEPHAtOPODA. 



335 



I. ArxuMitlU'r. 
F«nil« pnnicM wllh > olcmotit, «itFrniil, monalhiUtDOUt 
ibfU. (coMeit \rt *)** wcbbtil otramilint o{ tlio dorul amu. 
Gen. vfi w w J Mte. 

Shell inicnul, rudlmtniaiT, uncolcIRcd. No pallial lin« in 
aiMC. IIL Grn. tiiAywu, Trtm^iltfui, MMtiiu, rinnMlrfui. 

tloN B. Dix:aiv>1M. 

ArmtfiglU,vnlA Ivf tlavM " OnUuta ;" tvrbn ftdtu td ilaled. 

Sficll an inleniBl horny "pen" or "^ladiui." Pint moMly 
lennia*!. IIL Geo. luligo, OiytliMatfMu, Omaiartrtfia. 
Fttm. 4. BdtmmtiJa. 

Sb«ll intenuil, compowd of t conical chjiin1iert<l portion 
("phngmftcon* J wild a mujfiiial dnhunck. tomctiinM pro- 
dsred iMo a homy \t\tM or " ptti," ana lodeed in ■ cyHndrivl 
Kbnwt "foa.!^ 111. Cm. Utifmnilfi. iMtmHiltOi, SAm- 
milmlttt. 
Fam. c Sifimb. 

ShrtU calcueoiK con*i>Iin|[ of ■ broad, Umlntr pUtc Icml- 
DMinc (KHtcrlofly In an Impnfwdy chambered apex (" phragmo- 
COM ). III. Gen. Stfia, fftUftrm, SfiraJimlra, 
Fitm. & S^irnIiJj. 

Slwll initmil, nacreous thamlmcJ, 'liKoida] ; the whorl* 
iqianle ; a vcetral liphuncle. Ctn. SfiruU. 

t II. Tt:TRAMlA>'ClttATA. 

Animal with (uur eElU; arm* morv Ihan Ifn, wilhuutmcltara; 
ao ink-faai; : ihcU cxtmial, ctiambmd, and Ktphuiided. 
Aaa. 1. ManliliJit. 

SMartsof ihe shell >iinpl«; Ihf liphunclc central, tub-ccntraJ, 
er Mar the concaviiy o( ihe curied shells timple. 
Sil^fiimilY .Vantiliij frvfrr. 

Badv^chaniber lapMious ; aperture simple ; Bphtinde 
MBUaloc intcnuJ. IIL Ceii. J^'aithlvj, Liatka, TirptMt- 

Sitt-fiimilr OrOtrtTMU^ 

Shell tti^ht, carved, or illtcoidal ; hod]h<haBber 

moll ; aperlure conlmcieil ; upbundeconpUcaled. llL 

Gen. OrtAtftrai, finigmtttrai, CjrrHttr*!. 

n. t. AmmntiitKta. 

Stieil dlicoiilal, carved, iplnl, «r ttiai|>hl : body-ctuunber 

cLca^lcd i openare EuanM CT prootcMf, or cloatd by an opcr- 

cirflUH I aatiMM angoiMet^ lotwcL at felMOMM ; riplnnclo n> 

KhmI or domi (on the CMtvtx aide ol ih* carved ^!U. III. 

Geo. AmmtitUti, CtntiUi, BtKulila, TkrrUiUi, SeafHtti, Amty 



336 MANUAL OF ZOOLOGY. 



CHAPTER LII. 

DISTRIBUTION OF THE AfOLLUSCA PROPER 
IN TIME. 

Remains of the MoUusca proper are found in greaier or In 
abundance in almost all the stratified rocks from the com- 
mencement of the Silurian period up to the present daqr. 
Speaking generally, the Tetrabranchiate Cephalopoda are ^ 
chief representatives of the Mol/usea in the Palaeozoic iock% 
the Lamellibraiickiaia and the Dibranchiate Cephalopoda in the 
Mesozoic rocks, and the Goitert^oda in the Kainozoic paiod; 
but ail the primary classes are represented even in the Lowtr 
Silurian rocks. The foUlowing are the more notic:eab1e f»c8 
relating to the distribution of the various classes in past tinu. 

Lamdlibranchiata. — The LamelUbranchs are known to hire 
existed in the Lower Silurian period, and have steadilf iD' 
creased up to the present day, when the class appears to hire 
attained its maximum, both as regards numbers and as r^ardi 
variety of type. The recent bivalves are also superior in 
organisation to those which have preceded them. Upon the 
whole the Asiphonate bivalves are more characteristicallr 
Paleozoic, whilst those in which the mantle-lobes are united, 
and there are respiratory siphons, are chiefly found in tbe 
Secondary and Tertiary epochs. One very singular and abff- 
rant family — viz., the Hippurifida — is exclusively conlined CO 
the Secondary rocks, and is, indeed, not known to occur be 
yond the limits of the Cretaceous formation. The Vmeri^ 
which are perhaps the most highly organised of the families (f 
the Lamtllibranchiaia, appear for the first time in the ChrfiK 
rocks, and, increasing in the Tertiary period, have culminittd 
in the Recent period. 

Gasteropoda. — The Gasteropoda are represented in past liise 
from the Lower Silurian rocks up to the present day. Of the 
Bratichifera the Holostoinata are more abundant in the Pal» 
zoic period, the Siphonostomata abounding more in the S^ 
condary and Tertiary rocks, but not attaining their maximiBi 
till the present day. The place of the carnivorous ^pht^ 
stomala in the Palxozoic seas appears to have been filled bj 
the Tetrabranchiate Cei)halopods. The branchiate Gasteio- 
pods of fresh water are chiefly represented as fossils by Ht 
genera Paludina, VaknUa, and Aiitpullaria. 

The llelcropoda are likewise of very ancient origin, ha^inj 
commenced their existence in the lowest Silurian deposits. 




MOLLUSCA: DISTRIBUTION. 



337 



genera Sei/avfhm, l^rulOa, CyrtelUts, and Mathtrta, are 
a.lruatt exciuxivel/ Palaeozoic; Beiltr<iphina is found in the 
5^ajlt ^Scoondaiy), and (^inaria haa been dctecled in the 

The Putmonatc G^ileropida, as was to be anticipated, are 
lot found abundJinily as fossils, occurring chiefly in lacusirine 
^nd csiuarioe deposits, in which the genera Limnaa, PAjia, 
Wnf^/iu, Sic. ait anwnfpi those most cointnonly ic]>resented. 
■i.''hese, however, are enliret)' Mcsoxoic and Kainuxoic In the 
PaLKOioic jicriod the «>lc known rcptescnljuivts of the /W- 
^n^Hi/era arc the /'ufia Ptimta and ZenUts prUau of the Car- 
boaifemis locks. 

Ptervffda. — The Ptcropods arc not largely represented in 
fonilifcrous deposits, but ihcy have a wide range in time, ex- 
teixling from the Ixiwer Silurian roclcs up to the present day. 
The TAeea and C^nularia of the Palxoioic period, if truly 
X^teiopoib, are of comparatively gigantic size, and extend from 
the Lower Silurian lo the Carboniferous period. The Siluri.-in 
foviil, TaUantJUes, is asicrted by M. Baminclc to be a Ptexo- 
I>ckI, but it is usually looked upon as a tubicolous Annclldc. 
The recent genus liyalta is represented in the Tertiary period 
(MioccncX 

C(fhahp»da. — The Ccphalopods are largely represented in 
all the primary groups of suatified rocks from the Lower Silu- 
rian up to the present day. Of the two orders of Cephalopoda, 
the Tttratrawhiala is the oldest, attaining its maximiun in the 
^alaN)iok period, decreasing in the Mcsoxoic and Kainozoic 
epochs, and being represented at the present day by the single 
foran Nautiius pempi/ius. Of the sections of this order, the 
JVamiMa proper and the Orth^eratidit arc prc-emineotiy 
l*Bls«)ioic and tlie AmmoniliJa are not only ]>re-eminently 
l>ui are almo«i exclusively Secondary. Of the abundance of 
the two tbrrocT families in the Silurian seas some idea may be 
obtained when it U mentioned that over a thouuind species 
have l>een described by M. Harrande from the Silurian basin 
of liohemia atone. The NautUida proper have gradually 
decreased in numbers from the Paiaiozoic through the Sccond- 
*^»odTeniary periods to the present day. The Orthoifralida 
*!>«! o«t much sooner, being exclusively Patieojioic, with the 
txcejuion of llie genera Onhocfras itself and Cyrtoceras, which 
*"Jt>ivcd into the commencement of the Secondary period, 
''nslly dying out in the Trias. 

I'hc second family of the Ttirabran:hiala — viz., the Amm^ 
»»i'i,(lB— is almost exclusively Secondary, being Very largely 
''ci'resented by numerous species of the genera AmnvmUa^ 

r 



338 



MANUAL OF ZOOLOGY. 



Ctraiitfs, Batulila, Turrilifa. &c. The only PulieoxoieKaai 
arc Goniatitts an<l Baarilet, of whkh the former is (bund fin 
the Upper ijilnriaD to the Trias, whilst the latter is a Dc*^ 




Fi& i».~Slic11tfifSK(>ii4)nrC«phil«fol>. 



HmhOh atimmMm i i ~ ' 



nun fomi. The genus Ctratittt is characteristically TriiuK. 
but it is said to <xicvs in the I>cvociian rocks. Alt the rimi» 
ing genera are exclusively Sec<Ki>dary, the genen £»atka. 
Tttrrilitti, Hamiia, and Pljttfuxeras being cooiinecl to the Cff- 
taccous period. 

Of the Dibranehiate Cephalopoda the record b lea* pcffat 
as thc>' liave ri:w Klniciun:s whieh are enjuhle of )ire>eTV4lvA 
They attain their maximum, as fossils, vhonly after their r>; 
appearance in the Secondary rocks, where they arc rcpic»ei>"'^ 
hy the large and importrint family of the IMtatitilidet. .S « 
of ihe Trulkidet and Stfietda arc found both in the SccockHO 
and in the Tertiary rocks, and two species of Argonaut to* 
been discovered in the later Tertiaries. No example i * 
Dibrandiiate Cephalopo<) is known from the I'aheouic ^ 
posits, and the order attains its mutinum at the prcKU ^ 



SUBDIVISIONS OF IMVERTEBRATA. 



339 



CABULAR VIEW OF THE CHIEF SUBDIVISIONS 
OF THE INVERTEBRATA. 



r 



SUIl-KIN<;i)OM I.— PROTOZOA. 

GtiTMJiKlSlltM. 

Class II. RHiiofonA. 

Order t. Muncra. 

2. AmcebcsL 

3. Foraminifura. 

4. Kadiohrii 

5. Spongi^ 
Class III. Infusoria. 

Order 1. Sitttoria. 

z. Ciliuto. 

3. l-lAgclUu. 
SUB-KINGDOM ll.~CCELEXTERATA. 

Class I. Hvurqzoa. 

Su^Imi A- JfjJrgida. 
Order i, Hydrida. 
J. CorynidiL 

3. Srnulanda> 

4. Csmpamilnridii. 
SmMmj B. Sifi&nDfi/iora. 

Order ;. Calyco]>horidx. 

6. Physoijliorida:. 
SuMast C. Disefph->ra. 

Order 7. Meduxiilie. 
SuMxitt I). I.uftrnarida. 
Order S. I.u«:mariadic. 
9. Pc1agid». 
10. Rhiiostomidx. 
SuMau E. Graft^Uidm, 
Class II. Actisozoa. 

Order 1. ZoaniharuL 

Sub-order d. Z. Malacodcnnata. 
h. Z, SclcrolMsica. 
f. Z. Scterodennato. 
Order 1. Alcyonaria. 

Fam. a. Alcyonidic 
^. Tubiporidjc 
e. Pcniiittulidas. 
</. Gorgooidac 
Order 3. -Iltigou. 
Order 4. Ctenophora. 



340 MANUAL OF ZOOLOGY. 

Sub-order o. Stenostomata. 
b. Euiystomata. 
SUB KINGDOM IIL— ANNULOIDA. 
Class I. Echinodermata. 
Order i. Cystoidea. 

2. Blastoidea. 

3. Crinoidea. 

4. Echinoidea. 

5. Asteroidea. 

6. Ophiuroidea. 

7. Holothuroidea. 

Class II. Scolecida. 

Division A. Platydmia. 
Order i. Txniada. 
3. Trematoda. 
3. Turbellana. 
Sub-order a. Planarida. 
b. Nemerdda. 
Division R Nematelmia. 
Order 4. Acanthocephala. 

5. Gordiacea. 

6. Netnatoda. 
Division C- Rotifera. 

Order. Rotifera. 

SUB.KINGDOM IV.— ANNULOSA. 
Division A, Anarthropoda. 
Class I. Gephvrea. 
Class II, Annelida, 

Order 1. Hirudinea 1 Abranchiata. 

2. Oligochseta J 

3. Tubicola Uranchiata. 

4. Errant la \ 
Class III. Ch-etognatha. 

Division B. Arthropoda or Articulata. 
Class I. Crustacea. 
Sub-class 1. Mpizoa. 
Order i. Ichthyophthira. 
z. Rhizocephata. 
Sub-class II, Cirripcdia. 

( Balanidic. 
Order 3. Thoracica. j \'etrucitLjc. 

4. Abdominal ia. 

5. Apoda. 



^^ SUBDIVISIONS OF IKVERTEBRATA. 34I ^d 


m SuMatJ III. £ntomMraat. ^| 


^^^ Order 6. Ostracoda 
^^H 7. Copepoda 


■ Legion Lophyropoda. ^^ 


^^H^^ 8. Cladocera 


^J 


^^^^^H 9. Phyllopoda 
^^^^H 10. TViloblu J 


' Legion Branchiopoda. ^^^H 


^^^^^H ti. Merostomato. ^^| 


^^^^H Sub-ordcT a. Xiphosura. ^^^H 


^^^^^H Eurj-pterida. ^^^^| 


V JbMwr IV. Maiatvslradi. ^^^^H 


^^^ Older II. Lxmodipoda 


Division A. ^^^^H 


^^B 15. Iftopoda 
^^^^^_ 14. Ainpliipoda 


Edriophthaltnala. ^^| 


^^^^^B 15. SiomajKida 


Division B. 1 


^^^^^H Dccapoda 


Podophthaluuita. 1 


^^^^^P Tribe a. Macruia. 1 


^^^^^^ ^^^J 


^^y firachyura. ^^^H 


Class II. AiucnNiDA. ^H 


Dhfisha A. 7'risifuaria. ^^ 


Order i. Podosoniatx 


3. Acarina. 


x. A<]elaithroaonuta. 
Ohtsim \\, Pu/mmaria. 


Otdcr 4. Pcdipalpi. 


5. Arancida. 


Class III. Mvriapoda. 


Otder I. Chilopoda. 


^_ t. Chilognalha. 


^^B 3. FauroixxU. 


^^^jUS IV. ItrSECTA. 


■ Sui-^/aa I. AtHdaMa. 


H Order 1. Anopliira. 


^^_ 3. Mallophaga. 


^^B 3< Thyuniim. 


^^^ Sii-dus 11. HemimdaMa, 


^^^ Older 4. Hcmipicra. 


^^H 5. OnhojXeTa. 


^^V (t, Nciiniptera. 


■ SiA-dass III. Hfilmitaabfila. 


B Otdcr 7. Aphanipicra. 


B 8. Diplcra. 



342 MANUAL OP TOOLOGY. 

9. Lepidoptera. 
10. Hymenoptera. • 
ti. Strepdptera. 
12. Coleopten. 

SUB-KINGDOH V.— HOLLUSCA. 
Division A. Molluscoida. 
Clais I, Poiyxoa. 

Order I. Fhylactolacmata. 
3. GynuKdiBiiiata. 
Class II. Twiiatia. 

Order i. Ascidia. bianchialia. 

2. Ascidia abdomtnalia. 

3. Ascidia larvalla. 
Ciass III. BrachU^oda. 

Order I. Articulata. 
3. Inarticulata. 

Division B. Mollusca Pkofer. 

Class IV. ZamellibraneAiata, 

Secdon a. Asiphonida. 
b. Siphonida. 
Class V. Gasteropoda. 
Sub-dass I. Branchifera, 
Order 1. Frosobranchiata. 

Section a. Siphoitostomata. 
b. Holostomata. 
Order 3. Opisthobnincbiata. 

Secdon a. Tectibranchiata. 
b. Nudibranchiata. 
Order 3. Nucleobranchiata (Heteropoda). 
Fam. a. FiroHdre. 
b. Adaatids. 
Sub~dass II. Pulmonifera. 

Section a. Inoperculata. 
b. Operculata. 
ClassWl. Pteropoda. 

Order 1. Thecosomata, 
3. Gymnosomiita. 
Class VII. Cfphalopoda. 

Order 1. Tetrabranchiata. 
2. Dibranchiata. 



PART 11. 



VERTEBRATE ANIMALS 




^^ERTEBRATE ANIMALS. 



CHAPTER LIII. 



General Ckakacters and Divisions or the 
Vertebrata. 

ti five Bub-kingrfoDis which »e have previously considered — 
'., the Pr^ifs^i, Calotternta, AnnuIfiJii, AitHnhsa, and MM- 
a— were grouped together by the French nnlunliKt I^iinarclc 
fciin ODe great division, which he termed Inx>ert^raia, Ihc 
nainiog members of the animal kingdom constituting the 
iiion yerifh-ata. The division I'frtfirafa, tlioiigh inchid- 
j O&ly a single sub-kingdom, is so comjiact Jind wc]|-markc<l 
Hvision, and its distinctive characters arc so numerous and 
■nporunt, that this mode of looking at the auiinul kingdom 
V my mie, a very convenient one. 

n>e sub-kingdom Vtrtrh^ala may be Khort))- defined as com- 
ting aHtmals in ichUh tht ivtty is eempestd of a number of 
*tilt t/gments, arrangtJ a/wg a longiltidinal axis ; the nenvut 
frm « in itt main matsa dortai, and the neural and haemal 
•i"w tf the body are afarays eompletely fhul off fn>m one an- 
" by a parikian ; the limbs are never more t/iaii feur in 
Mo', and are akcayi iunted away frsm the Keura/ aspect cf 
jtrdy; wwsl/y there is the bony axis knOten as the " spifte" or 
'triebraJ euiumH," and in aU the ttrtuturt huram as the " tuta- 
•'rf" it present — in the embryo/, at any rate. These cbarac- 
1 dittin^piish the Vertebraia, as a wlwle, Trom the Iiaerte- 
Mt; but it is necessary to define thcK; broad diflerenoei 
3tt minutelyi and to consider others which are of Itttlc less 
if«(lanc«. 

One of the most obvious, as it is one of the most funda- 
enial, of the distinctive characters of Vertebrates, is to be 
und in the shutting olf of the main masses oC ihc tttnofos 




34^ MANUAL OF ZOOLOGY. 

system from the general cavity of the body. In all Ato*- 
irate animals, witKout exception, the body (fig. 133, A) m^ 
be regarded as a sing/e tube, enclosing all the viscen; md 
consequently, in this case, die nervous system is coBtuned 
within the general cavity of the body, and is not in any «^ 
shut off from the alimentary canal. The tian&vene sectiaiv 
however, of a Vert^rate animal exhibits hoo tubes (fig. 123, ^, 
one of which contains the great massestff the nervous systm 
— that is, the cerebro-spinal axis, or brain and spinal ooA 
— whilst the other contains the alimentary canal and the daif 
circulatory organs, together with certain portions of the ncr 
vous system, known as the "ganglionic" or " qrm pathetic* 
system. Leaving the cerebro-spinal centres out of sight for I 
moment, we see that the lai^er or visceral tube of a Vertebrate 
animal contains the digestive canal, the hxmal ^stem, and 1 



-,(* 





Fiz. 193- — A, Tnnsvnc icction oT ihc bodr of one of the hisho- rumi'i^ipfa ■ 
Body-wAll : b Alimentary canal ; c Hcnut ijntein ; ■ Nervous tfvxia- B. Tiar 
verx Kctinn of the body of a Vtrlthratt odiinil ; ■■ Body-wall; h Afi^dCvf 
canal; c Hzmal ■yflem; ■ SympalhcLlc lyittm of Dcrvts ; ja' Csvbr^^liaal fjfls 
ol ncfv»; ik liolochoEii 

gangliated nervous system. Now this is exactly what is {at- 
tained in the visceral cavity of any of the higher Invertebntc 
animals ; and it follows from this, as pointed out by Von BieCi 
that it is the sympathetic nervous system of Vertebrates lAich 
is truly comparable to, and homologous with, the nervoos sj> 
tern of Invertebrates, The cerebro-spinal nervous centres rf 
the VerUbrata are to be regarded as something superadded 
and not represented at all amongst the Imtrf^raia. 

The tube containing the cerebro-spinal centres is fonned « 
follows : — At an early period in the development of the (»■ 
bryo of any Vertebrate animal, the portion of the ovum • 
which development is going on — the "germinal area"— In- 
comes elevated into t«-o parallel ridges, one on each side rf 
the middle line, enclosing between them a long groove, whid 
is known as the " primitive groove" (fig. 1 14, A, B). The ridgS 
which bound the primitive groove are known as the "lanunc 



GENERAL CHARACTERS OK THE VERTEBRATA. ^f 



donales ;" aod Ihcy become mon: nnil morr raised up. till (hey 
uhinuUety inert in the middle line, and unite to fomi a lube, 
within whieii the cetcbro-spinal nervous ccnires arc developed. 
It f(>llows from its mode of forruatjon that the inner wall of the 
tube I'omied by the primitive groove, wliich remains as the 
_jcptHm U-twccn the tciebro-spinal canal and the body-cavity, 
"" I nothing more than a {tottion of the |>^imiti^■e wall of the body 
" the embryo. And there ap[)eani to be little doubt, as bc- 
Hcved by Rcnuk and Huxley, that the cercbro-spinal nervous 
centres ate " tlie result of a modification of that serous layer 
of the t!cnn, whidi is continuous elsewhere with the epidcnais" 
(Htuky). 




■V- tt±—Km\ff ilasy «f Vtmbnte. A, rnnlaianiH pmbiti tni* «r lit* onim 
tl • khili. Aoi^ iW priaiUn man tilttt Bhrhilt). B, fmUt vitw (tf iht 
WPifr Cm DkMUi nvruMtifaf a* utfiuiit and iLllAatoit: t Embrrti m Am^ 
■n: ■ Uatiillol Mack . t MluuUi / IMIcIt at itit «ll>nt»ii, ■fimwdt ib« 
... .. D, u«Ul of w cabrra, ihDiriaa the Tiunl u^B (p r)i 



Another remarkable peculiarity as regards the nervous sys- 
tem is found in the bet that in no Vertebrate aninul does the 
•limentary canal pierce tlie main masses of the nert-ous xystein, 
but tum« away to 0]>en on the op|^oKite side of the body. In 
tboot InvertebraiCT, on the other hand, in which there is a 
Helt-develoiied ncr\ons system, this is ])crforated by the giiHct, 
So that on oesophageal ncn>c-colIar is formed, and some of the 
Hervoas centres become pnc-ccsophageal, whilst others are 
|K)«t-cc»ophagcaL 

Funbomore, the floor of tlie "primitive groove" in the 
Vnbryo of all Vertebrates has developed in it at an early 
|icrio«l Ihc stntctuie known as the " noiochotd " or " chofda 
vAonatlb" (fig- 133, B, M). This Mructure, doubtfully present 
in any Invertebrate, is a scmi-gebtinous or cariiltginous coU 



348 



MANUAL OF ZOOLOGV. 



leclioii of cells, rorming a rod4ike axis, nhtcb tspers « bo(h 
end3, and extends along the Boor of the cercbro-spiiul cu4 
supporting the cerebrospinal ncrvotis centres. In some Vo- 
tebraiei, such as the Lancclct {Aw^ioxui), the notocbord ti 
persistent tliroti(|hout life. In the majority of cases, faoircm; 
the noiochord is replaced before maturity by ihe cUucDK 
known ax the "vertebral (.-olunrn" or "liAck1>onc" ftta 
which the sub-kingdom VerlArata originally dcri\'cd ils uat 
This is not the place for an anatonii<;al description of tte 
spinal column, and it is sufficient to state here that it is esK» 
tially composed of a series of canilnginous, or ntore ot len 
completely ossified, segments or vtrMm, arranged so as to !:-!r: 
t longitudinal axis, which protects the great masse* ol 
nervous system. It is to be remembered, however, llui tii 
Vertebrate animals do not possess a vertebral colinsD. T^ 
bU possess a iwloekcnl; \nn this may t>e |)er«istent, aat! ia 
many caires the devel<^>nicnt of the spinal colutan is cxtroulr 
imperfect. 

Another embryonic stnicture which is chaiacteristic ofiD 
Vertebrates, is found in the so-called "visceral arches" tad 
"clefts"(fi({- >S4, D). The "visceral arches" are a series of p«r- 
altel ridges ninninB iraivsversely to the axis of the body, ab- 
ated at the sides of, anil posterior lo^ the mouth. As devcloft- 
meot proceeds, the intervals between these ridges becont 
({Tooved by depressions which gmdtully deepen, unti] dirr 
become converted into a scries of otwnings or " clefts." mhm 
by a free communication is eslsblislicd between the uptxr pst 
of the alimentary canal (pharynx) and the external tneoituiL 

The limbs of Vertebrate animals are always aniculalo) B 
the body, and they are always turned away from the annl 
aspect of the body. They may be nlioKetlier wanting, or ll»«T 
may be parti.illy tindevcloped ; but there arc never more tiufl 
two pair^ iind they nlways have an internal skeleton (or the 
ailachnicnt of the muscles of ihc limb. 

A specialised blood- vascular or " hxmnl " system is \*ttm 
in all the i'ertetrata, and in all except one— the AmfAmxK— 
there is a contractile cavity or /teart, which never cOMin if j 
lest than two chambers provided with valvular apcrtiutL Ib | 
all Ihe VertePraia llie heart is essentially a resfira/fry hotn— I 
that is to »y, it is concerned with driving the imi>urc or wnw 
blood to the breath ingor^uu ; and in its simplest form <&tliti) 
it is nothing more than this. In Ihe higher Vvriebrates, I 
ever, there is superadded to this a pair of cavities wt 
concerned in driving the pure or ancrial blood to the I 
In the case of the Iktanunals, these mo circulations are 




GEN'ERAL CHARACTERS OF THE VERTEBRATA. 



tpoken of as the " lesser " or " pulmonaty " circulation, and die 
*• greater " or " ^icmic " circulation. 

In all Vertebrates there b that peculiar modifiouion of the 
venous itystnn which is known » the " hcfKitic |>ortal sysieni." 
Ttutt is to say. a portion of the blood which ts sent to the ali- 
metitaiy canal, instead of returning to the hean by thv ordinary 
^TCins, IS carried 1o the liver by a special v«sd — the iv«m 
/tffttr — which ramtlies through this oi^ after the nonncr of 
on an cry. 

In nil' Venebratcs, also, is found the peculiar system of ve»- 
seU known u the " lacteal system.' This is to be regarded 
■U an appendiige of the venous system of blood-vessels, and 
consists of a series of vessels which take uji the |iroduct3 of 
digestion horn the atimcntar)- canal, elaborate them, and finally 
ODpty their contents into the veins. 

U^Iy, the masticatory organs of Vcncbram are ino<!i6cd 
portions of ihc walb of the head, and never *■ bard productions 
of the alimentary mucous membrane or modified limbs' (Hui- 
tey), as they are amongst the Invertebraia. 

The abot-e are the leading characters of the Vtrtebralix as a 
wliole : \m\ before going on to consider the primary divisions 
of the sii)>.kingdoni, it may be as well to give a vct)' brief and 
general description of the anatomy of the higher and more 
typical Vertebrates, coininencing with their bony framewodc or 
ikclcion. 

The iktlfion of the Verifbrata may be regarded as consistii^[ 
esientiaUy of the bones which go to form the head and trunk 
on the one haitd (sometimes culled the " oxi.il " skeleton), and 
of those which (brrn llie supporu for the limbs <" ajiix'ndiciilar" 
ikeleton) on the other haiid. I'he bones of the head and 
tmnk tn.1}' t>c lookctl upon as essentially composed of a series 
of bony rings ot segments, arranged longitudinally, one behind 
the other. Anteriorly these segments are mud) expanded, and 
likewise much modified, to form the bony case which enrjoses 
tbe brain, and which is termed the eraniiim or skulL Behind 
Ibe head tlie segments enclose a much smaller cavity, which is 
Called the " neural " or spinal canal, as it encloses the spinal 
cord 1 and they are arranged one behind the other, forming 
the vertebral column. The segments which form the vertcbrai 
aolumn arc colled "vcrtebnc," and ihey have the following 
tetseral stntcltirc: — Each vertebra (fig. itj. A) consists of a 
Mitral piece, which is the fund.! mental and essential element 
»r the lencbra, and is known as the " body" Of " centrum" (r), 
Prom the upper or posterior surface of the centrum spring two 
MOy archo (n n), which are called the " neural arches " or 




350 



MANUAL OF ZOOLOGY. 



" neunpophjrMs" because thc>' Tonn with the body a aiai- 
the " neural canal " — which encloses Uic spinal cord. Frem 
the ]>oin[ w^ere the neural arcltes meet behiixl, there is usuiU; 
dcvcloi^ed a longer or shorter siune, which is temed the "^ 
nout procCTs " or " neural spiite " (s). From the neural artba 
there are also developed in the iy|>ical vertebra two |iroca» 
(tf rt), which arc knowii as the "aititular" processes, or "lyp- 
pophyscs." The vertebra; arc united to one another paitljr bf 
these, but to a greater extent by the bodies or " centra.' Frco 
the sides of the vertebral body, ai the point of Junctiao wi 
the neural arches, tlicrc proceed two lateral processes iJJi 
which are known as the " transverse processes.* (In the t^yiai 




Rft lis —A. Li 
t Kainl apmc 



ifi Wtikle: ttlotrm entanmi ■■ Mfwriw*' 



. . . sMinnil At Hunl an^ ■ • 






iiUctit i i Slenumt tiilh hxoul tpDC t^fHT Ovrh.^ 



vertebra the transverse processes coatist each of two pieces, a 
anterior piece or " parapophysis," and a posterior piece tf 
" diapophysis." These clcmenis form the wrtt^a of (lit 
human anatomist, but the " vertebra " of the transceodcntil 
anatomist is completed by a second arch which is pl3cc«l Im- 
neath the body of the vertebra, and which is called the " I*- 
mal" arch, as it includes and nrotects the main iirKanx of At 
circulation. This .lecond arcn is often only recogniMhle wA 
great difhcult)', as iis parts are generally much modifiol hu> * 
good example may be obtained in the human chest, or ia tte 
caudal vertebra of a bony fish. 

I'lie hsroal arch in the case of the human thonu (fig. ii;> 
B) ia formed by the ribs (r r) and the coalal cartilages (//h 



GENERAL CHARACTERS OF THE VERTEBRATA. 351 

and is compldcd in front by the breasl-bonc or slnntiin (t), 
which in fomc coses — but not in man — dcvciops a spine (the 
luDOul spine) which corresponds to the ncursJ spine on the 
opposite aspect of the vertebra. 

It follows Irom the abov^, that the typical vertebra consists 
of • ceninU piece or body Iram which two arches sue given off, 
one of whit h protects the great massea of t)ie nervotisi syxtem, 
and ta therefore uid to be "ntunil;" whilst the otlier pro- 
tects the main origans of the circulation, and tK therefore said 
to be "haemaL" ITw oonespODdcncc of tlic typical bony 




'Ccniialr>(n;^I>iinkl ratios : )ltiab>rn|tw;<SMfua: 




acDl or rertehra with the doubly tnbular atnicture of the 
tn all VctiL-bratcs it thus too obvious to re<[uire to be 
illy pointed out. 

A general rule, the vertebral column is divisible into a 

of distinct rei^ons, of which the following are recog- 

Je in man and in tlw higher I'frMra/a: — t. A scries of 

! which compose the neck, and constitute the "ccnriaJ 

i" of the spine (fig. ri6, i-). 3. A number of venebne 

I asually carry well 4leveloi>ed ribs, rikI fonn the "dotfaal 

1 ■ (</), 3, A Kciies of vcrtcbnc which fonn the region 

'the loins, or " lumbar region " {6). 4. A greater or k«R 



3S2 



MANUAL OF ZOOLOG%'. 



number of vertebrae which constitute the " sacral Tcgwwi," wi 
are u-sually amalf^aiimted or " ancltylused " together to fom i 
single bone, the "sacrum" (f). 5. The spinal columr 
completed hy a v.iriable number of veHebtae which const:- l : 
the " atudnl " re^n, or tail {/). 

An regards the siuff of the yertrira/a, it hM been tbou^ 
advisable not to enter into an^ general details here, pinlf 
because the subject is one which can onl^ be properly di»- 
cu&sed in a work specially devoted to Human or ComparUiw 
Anatomy, and jianly because there is stitl much diversij of 
opinion as to the exact composition of the skull. There b, 
however, » very general concurrence of opinion tJiat the ikull 
ijt composed of a number of separate segments, and this b t 
Iioini which it is important to remember. By Owen, and bj 
msny other competent authorities, th«c inanuil segments m 
looked upon as being nothing mote than so many vertttt. 
the neural canals of which arc greatly cx|>am!cd lo ctxiett 
the brain, whilst the hxnial arches are vcrj- greatly modifie<l w 
serve diflerent purposes. This view is not accepted by Hai- 
ley, but the general fact that the skull is composed of scfitnir 
segments appears to be univcTsally .idmitted. I'he only poitiot 
of the bony framework of the head which it is al>»olu:r!;i 
essential to understand, is ihc lower jaw or " mandible." The 
lower jaw is sometimes n-anting, but when present, il con>a» 
in all P'rriebrata of two halves or " rami." which arc tmilwJ 1* 
one another in front, and articulate sepaiatcty with the kbJI 
behind. In many cases, each half, or "ramus," of the lo*a 
jaw eonsi.tts of several pieces united to one another by sntum. 
but in the Mammalia eadi ramus consists of no more than a 
single piece. The two rami are verj- variously connected w* 
one another, being sometimes only joined by ligaments lai 
ntusclrs sometimes united by cantuge or by bony suture, tfd 
sometimes fused or anchylosed with one another, so as to \tin 
no e\-idcncc oi iheir true composition. The inndc hy whii 
each ramus of the lower jaw articulates with the skull tin 
varies. Id the Mammalia the lower jaw aiiicuUtes wild » 
cavity formed on what is known to human anatomists u Ac j 
temporal bone ; but in Birds and Reptiles the Iowa f" ' 
articulates with the skull, not directly, but by the iotervenu* 
of a s|>ecial bone, known as the "quadrate bone" or "m t>^ . 
ralum. 

As regards the limlii of Vertebrates, whilst matter diffEreftf* 
exist, which will be aftcrn'ards noticed, there is a KcMt' 
agreentcni in the parts of which they arc composed Ai * I 
n^e, each pair of limbs is joined to the trunk byineuiiA*' 



■general characters of the VERTEBRATA. 353 



cries of bonet which ako corrcspood to one another in gcn<:ra1 
Uitcture. The fore-ltmbH, often tailed the '*]>ectorai " timbs, 
ire united with the mink by meiuis of a bony arch, which is 
aJIod ihv "pcciornl" oi "scapular" arch; whilst ihc hind- 
■mb» ore similarly connected with the inink by means of the 
' pcMc srch." In giving a gencnii description of the pariK 
rhich compose the limbs and their su)'|iorting arches, it wilt 
w best to lake the case of a Mammal, and the depiinurcs 
rotn thia type wilt then be readily recognised. 

The pectoral or acaimlar arch consists usually of three 
>oncx. the "sca]»ila" or nhoulder-blade, the " corxcoid," and 
he '■ clavicle" or collar-bone; but in 
he great majority of the Mammals, the 
xmeoid is anchyloscd with the scnp- 
lla. of which it fonns a mere process, 
rb* scapula OTshoulder-b]adc(Ag. I a7,j) 
> asually pUccd outside the ribs, and 
r forms, cither alone or in conjunction 
riih the other bones of the shoulder- 
[tnlle, tlie lavily with which the upper 
inn is ntliculated. The comcoid, 
hough rarely existing as a distinct bone 
n the Mammals, pbys avery important 
;tan in other Vencbratcs, as we shall 
lee bereafler. Tlie cbvicles are often 
nuiing, or rudimentary, and they are 
ihe \tnt essentia) dements of the 
Kapular arch. 1'hc fore-limb proper 
eouists, firstly, of a single bone which 
EotlBl the upper arm, and which is 
haown as the iuiwrus (A). This arti- 
cnlates above with the shoulder-girdle, 
•ad is followed below by the fore-arm, 
*hich consbis of two bones, called the 
ihKm and u/jM. Of these the radivs 
il cUefly cotwemed with carrying the 
Mad. The radius and ulna are fol- 
■itved tiy the bones of the wrist, which 
**t usually composed of several bones, 
^ constitute what is called the tarput 
^y. These support the bones of the 
"Oqi of the band, which vary in 
lunber, but are always more or less 
>lindric^ in shape. I'hey constitute what is called the 
•etortw^i*/. The bones of the metacarpus cany the digits, 




/. 



Vs. It;. — Pntsnl Umb 

(After Onn.) t Onl- 
cl« . i Scftpii^ o* th'lul- 
dcr-bbilc ; t lluuimu : 
r Radiui; ■ Uha; a 
llood «l <h« tnhi, or aar- 



■ oltbc 




354 



MANUAL OF ZOOLOGY. 



which also Titry in auinbeT, but arc composed each of fan 
two to dtree cylindricatl bones, ithich are lciM>wii kt (bt 

Homologous paits arc, m a rule, readily recogniuMe m at 
hindJimb. IIk pdvic arch, by which the hin(l-hmt> it oniud 
wnth the tmRlc, coosbts of three [Hects— Ac 
i/ium. iuJiiiim, an] /uin — which are enn% 
anchyloscd together, axid form conjointly wtat 
U known as the MHrnHinnte Anv {Ag, 118, <). 
In n>o&t Manunals, the two innomhiatc bona 
unite io front hj a li^amenlous or csn3aj{iiiM 
■mton, and ibey consttiiute. witli tlie sacnim, «hfl 
is koows as the fidr-u. The hind-limb prape 
•-^K consistt of the following pons : — 1. The itnpi- 

booe orTbntr, corresponding with the huaea 
in the fow4inl>. i, 'llu- bones of the dual, 
corresponding with the radius and ulna of tt 
(•ytfA\a\\ and known as the A^u and jCMi 
Oi these, the ttbia is mainly or altogether oa» 
cened in carrying the foot, and it i» l^ 
shown to correspond to the radius. whiUl H* 
flfavU oocrcspoods 10 the ulna. j. The and 
bones of the aaUc, known as the larau, siJ 
nrro^ in iMntbcr in different cases. 4. A 
nrable wmberof qrlindrical botm (nocauh 
fire), which an catted the mitatarsvs, and wk 
cofrespood to the metacar|>us. ^. Lastly, tte 
metatanus carries tbe digits, which comist d 
from two to three small bones or fKalauga,* 
rt( ttt. - f«M> ia the fare-limb. 
y\fijj^3 "^^ «^l«wftw rrrfftw of Vencbraies wiB bt 
, fr*"?'**^ ,^ spoken of at greater length hereafter ; XnO, » 
'rr»ii.iiaL» brief sketch may be given here of the gtssil 
nCL.*.%^ pbctKuneoa of digestion. All Vertebrate m 
w^mmm; p BAh arc pcovidcd with a noutli bir the »- 
H,' -■ '* *" ccptiOB of food, and ia the great tnajocity i. 
cases the mouth ii fbnushed with Itrtk, «»kl 
are iwcd w ctiia c s merehr to hold the prey. Inn mo«e a»\ 
MO^r ■*> CM and bnbe iW food, and thus render it cspoUi , 
of d^jestK". T^c food b abo genciaU)' subjected ia •» 
""^ "~ : «•« of ■• sahvaiy" glands, the secretin* '' 

■I only to moisiai the fooiJ, and dim v 
VftannitiMi, but *ho to render sohttilc Ae 
WMrfaod Tbefood is neutwallownL* 
t^W-itTwAfaw* the mouth to the snw^ 



lERAL CHARACTERS OP THE VERTEBRATA. 355 



ling eflFecinl by a coni]>)ica(rd arnmgement of musdcs, 
ty the food is forced down the giillci (<rja/iAaptf) to tho 
■digestive cavityofslomach. Jn the stomach (lig. 119.^} 
td is subjected to two scis of actions) it is mechanically 
led and |;round down by the con«.Lant contractions of 
IKulu wills of tlie Ktoinadi ; and it h subjected to the 
)b1 aaion of a tpccial fluid necreted by the Mtotnach, 
lllcd the "^Iric juice." 'I'h is fluid has the power of 
hg altKirainoid siibsL-inccs to a soluble form, nnd \n its 
I the food is ultimately reduced to a thick acid fluid, 
the "chyme." Leaving the stomach by its lowci 
re (the pylorm), the chyme passes into the intestine, 
M portion of which is divided into several sections, but 
^tivcly known as the ".iniall 
^" Here the chyme is .lub- 
|to the action of three other 
\n fluid*; the (rile, secreted 
|)>ecial organ, the liver : ihc 
J/ii- juitf^ secreted by another 
[the luncrcas; and the into- 
Kmy, secreted by certain (jtands 
d in the muc<ni-i mcmbmne of 
|estine itaelf. ITie result of the 
iproceo is that the "ch)ine'' ^"';J 
juiely converted into a white. 
IC milky Ruid, which is called 
l" 'llic indigestible portions 
food |)as) from the small in- 
into a lube of larger dimcn- 
called the "large intestine." 
iponions of the food .is are 
Muble, and cn|iiible of being 
y«(l in nulritton, arc here 
into the blood, ihc use- 
ider being ultimately ex- 
on anal aperture. The 
ion of the lai^e intestine is 
less convoluted tlun tlie rest, 
called the " rectum." 
fluid and originally soluble 
of the food, and the chyle 

formed in the i>roccss of digestion, are taken into the 
le loMcs of which ihey serve to rei>air. Part of the 
tnterinls of the food is uken up dire<-tly by the 
reaseli, and is convened by the " vena ponac" \n \iit 




Im l.trn liMMina . * Kaoua, 



3S6 MANUAL OF ZOOLOGY. 

liver, whence it ultimately reaches the great vdna wfaidi nlo 
die heart The greater part, however, of the Uquc£edu(4 
constituting the chyle, is taken up, not by the blood-rend^ 
but by a special set of tubes, wtuch fonn a network in Ac 
walls of the intestine, and are known as the "lacteals* b 
these vessels, and in certain glands which are developed npoi 
them, the chyle undei^oes still further elaboration, and is nude 
more similar in composition to the blood itself. All the lactol 
vessels ultimately unite into one or more large vessels wfaid 
open into one of the veins, so that all the chyle is thus fiul^ 
added to the mass of the circulating blood. 

The blood, then, or nutrient fluid from which the tissaes m 
built up, is formed in this way out of the materials which at 
taken into the alimeniary canal as food. In all the VertebnU, 
with the single exception of the Lancelet (Am/Aiaxtu), tbc 
blood is of a red colour when viewed in mass. This is dnelii 



ti») f# ^« (9 ^-^ 



Fi^. 13Q,— .BIood-fnTpuscEcfl of VcTTrbntL a Red blood-di vci of bu ; i EBood. 
diici of Gooit ; c CnKodiLe ; J Fn^ ; t Sk^c 

the presence in it of an incredible number of microscq)ic>l 
bodies, which are known as the "blood-corpuscles," the fluid 
in which these float being itself colourless (fig. 130). 

In all \h^*Vertebrata the blood is distributed through 4t 
body by means of a system of closed tubes, which constitute 
the " blood-vessels ; " and in all except the Lancelet, the raeani 
of propulsion are derived from a contractile muscular caritf 
or " heart," furnished with valvular apertures. In the most 
complete form of circulation, as seen in Birds and Maminil^ 
the heart is essentially a double organ, composed (rf tw 
halves, each of which consists of two cavities, an auricle ud 
a ventricle. The right side of the heart is wholly coDccmed 
with the "lesser" or pulmonary circulation, whUst the \A 
side is concerned with driving the blood to all parts of the 
body (systemic circulation). The modifications of the ciimto 
ory process will be noticed in speaking of the different classes' 
Vertebrates, but a brief sketch may be given here of the drco- 
lation in its most complete form, as in a Mammal. In sudii 
case, the venous or impure blood, which has circulated throu^ 
the body and has parted with its oxygen, is returned by thegteU 



GENERAL CnARACTERS OF THE VERTEBRATA. 357 



veins tothc right auricle. FroiutJie right auricle (fig, t3t.ir)lhe 
blood pasKf by a valvular aperture into the right ventricle (i'), 
whence it U driven through the pulmonary artery to llic lun^ 
The right ride of the heart is therefore wholly respiratory in M 
fiiriction. Having been submitted to 
the action of the lungs, snd ha^'ing 
given off carbonic acid and taken up 
oxygen, the blood now becomes arte- 
rial, and is returned by Ilie pulmonary 
veins to the left auricle (a'). From 
the leri auricle the aerated blood passe* 
tlirouKh a valvular aperture into the 
left ventricle {i'), whence it is pro- 
pelled to all parts of the body by 
means of a great systemic vessel, the 
"aorta." 'ITic left side of the heart is 
therefore wholly occupied in carrying 
out the " greater" or systemic circula- 
bon. 

The puriAcation of the blood is car- 
ried out in all Vertebrates by means 
of distinct respirator)- organs, assisted 
to a greater or less extent by the skiiL 
In the Fishes, and in the .Amphibians 
to some extent, the process of rcspira- 
Oon is carried on by means of iraii- 
iiut or gilU — (hat ik, by organit adapted 
far breatliing air diuolved in water. 
These are, tnereftwe, often s[H>kcn of 
as '■ Branchiate" Vertebrates ; but the 
Amphibi^ins always develop true lungs 
in the later sl.iges of their existence. 
Jo the Reptiles, Birds, and Mammals, 
branchix are never developed, and the 
KBpiruion is alwa>'3 earned on by 
means of true lungtt— that is. by oi^ns adapted for breathing 
air directly. These are therefore often spoken of as the " Ab- 
ranchiate" Vertebrate*. 

The waste substances of the body — of which the most im- 
portant arc water, carbonic acid, and urea— are got rid of by 
the skin, hings, and kidneys. Under ordinary- circumstances, 
the lungs are nuinty occupied with the excretion of cat1>onic 
acid and watery vapour. I'he skin chiefly gets rid ot uipcr- 
Buoua moisture, but can alM in many animals excrete corbook 




ri* HI — liijMm of i>i( or- 

rcnnut fr^iciii ia iiuH«d 
bUck : ihq vt'Kil ffiimi it 
1a(i vhltc. >• Mifhl nuriilc: 

nuy 4rttry. cartTing rVEimia 
Uiod u iha lui^t: /F I^||. 
awiuniFtifii unyiiui ■rurial 
blooi hnn (tM liin|i : jr Lift 
■unci*; •' LaA vniincli; # 
Awu, umlnt •rHiMl Woid 
(S llic hmlyi t Vena an 
anyiBf YtMBiblMid M lb* 
bwn. 




358 MANUAL OF ZOOLOGY. 

acid as well. The kidneys are present in slmoct illVcrtebnIc 
animals, and their function is mainly to excrete water, and Ac 
nitrogenous substance known as urea. In the majonqr of 
cases the fluid excreted by the kidneys is ctmvCTed to it 
exterior by means of two tubes known as the uretei^ «lndi 
empty themselves into a commoQ receptacle, the urinarf Uvt 
der. In some cases, however, the ureters open into the la- 
mination of the alimentary canal (rectum). 

The nervous system of Vertebrate animals usually exhiUi 
a well-marked division into two parts — the cerebro-spinal sji- 
tern, and the sympathetic system. The cerebro-spinal systa 
of nerves constitutes the great mass of the nervous systm d 
Vertebrates, and usually exhibits a well-marked sepintioi 
into spinal cord {myelon) and brain {aitepfiaJon). The propor 
tion borne by the brain to the spinal conl differs much in dJ- 
fcrent cases ; and in the Lancelet a brain can hardly be said 
to be present at all. As already said, the brain and sfmil 
cord are always comjiletely shut off from the visceral atiia, 
and the)' are placed upon the dorsal surface of the body. Tbt 
nerves given off from the cerebro-spinal axis are symmetriaBj 
dis[!osed on the two sides of the body, and they are mainly 
concerned with the functions of " animal " life — that is to sit. 
with sensation and locomotion. The sympathetic system ol 
nerves is un symmetrically disposed to a greater or less extent, 
and presides mainly over the functions of " organic" or "T(|fr 
tative "' life, being mainly concerned with regulating the fiioC' 
tions of digestion and respiration, and the circulation of the 
blood. In its most fully developed form it consists of a doublt 
gaogliated cord placed in the visceral cavity on the under sur- 
face of the spine, and of a series of nervous ganglia, united br 
ner\'ous cords, and scattered mainly over the great viscera of 
the thorax and abdomen. 

The organs of the senses are well developed in the VaittraU, 
and those aiipropriated to the senses of sight, hearing, smdl, 
and tiute are protected within bony cavities of the head, "nie 
perfection of the senses differs much in different cases, but thCT 
are probably neier wholly wanting in any Vertebrate animal 
There are cases in which visioii must be of the most nidimcS' 
Uir>- character ; but even in these cases it is probable that that 
is a perception of light, even if there is no power of distinguid- 
ing objects. The only cases in which it would appear thit 
vision is really altogether absent, are those of animals placed 
under the wholly abnormal condition of spending their eiiS- 
cnce in darkness (such as the Preleus anguinus of the cai^esof 



> 



DIVISIONS OP THE VERTEDRATA. 



3S9 



it). ScmU, henring, and taste arc probably rarely, if ever, 
■Itbgethcr absent in Vcncbraics; though in muny cases their 
OigaiM art very rudimentary. Touch, or " tactile sensibility," 
n usually possessei) lo a greater or less degicc by the entile 
mftce of the body ; tiut tlie aense of touch U genenilty localised 
in cdlain particular parts, such at the apiientUijes of the mouth, 
the lips, the tongue, or the digits. 

In all f/rteiniJa without cxcq>tioi) reproduction i* carried 
on by means of the sexes, and in all the sexes are in dillfercnt 
individuals. No Vertebrate animal possesses the power of re- 
pcodneing itself by fmion or gemmation ; and in no case are 
OOnqMKite organtsms or colonics produced. Most of the Vcr- 
tabntcs arc iK-ifiarvM, ihat is (o say, the •on are expelled from 
the body of the parent either before or very shortly after im- 
pregnation. In uiher ca.in, tin; eggx are retained witUin the 
DOay o( the parent until the young are hatched, and in these 
auo the animal.i arc said to be mf-rirfiparMu. In other casies, 
ttgain, noi only is the C|<;g hatched within the ]>cirent. btil the 
embryo is retained within the body of the mother until its de- 
Tclopnient has been carried out to a greater or less extent ; and 
these aoiBub arc said tu be vhifiafVMt. 

Divisions OF THE Vkrtebrata. — The sulvkinKdom Ftrte- 
hnUa is divided into the Ave great clavier of the Fi^es {Pitai), 
Amphibian! (AmpAMa), Rejitiles (ffeflUia), Birds {Atrs\ and 
ftlamnuh {MammaJia). So far there is iicrifcct unanimity ; t>ut 
when it ix inquired into what larger sections the ^''cnebtnta may 
be divided, there is much difference of opinion. Here, the 
divisions proposed by Professor Huxley will be adopted, but it 
b necessary that those employed by other writers should be 
mentioned anil eaplsined. 

Oneof the commonest methods of classifying the Vfrtfhrata 
is to divide them into tlte two |>timary sections of the Branth- 
iaM and Abraitthiata. Of these, tlie Uranchiate Mciioii in- 
cludes the fishes and Amphibians and is characterised by the 
bcl thai the aninul is alwaj-s prondcd at some period of its 
life «ilh branchiie or gills. The Abranchiate section includes 
the Reptiles, Birds, and Mammals, and is characterised by the 
(set iliat the animal is never provided at any lime of lis life 
with eilb. Additional characters of the Branchiate Vcrxebnites 
arc, iltal the einbrj'o is not fumiilted with tlie structures known 
Is the amnim and allaateit. Hence the Branchiate Vcrlcbialcs 
Brc often *]>oken of as the Anamni^a tmd as the AnailatilfidM. 
In the Abranchiate Vcnehrates, on the other liand, the em- 
fai^o is always provided with an amnion and allantois, and 




3«o 



MANUAL OF ZOOLOGY. 



hence this section U spokeo of as the AmttMg or is the jf' 
hntniiifi].* 

By Professor Owen the Ftrittrata are divided into the tn 
primary sections of the Hamaloerya and the HamaMhriM, tiae 
charaetera of the blood beins taken as tlie diMJnctive cfainC' . 
ter. 'Hie Hamatocrya or Cold-blooded Veiteliratcs comiviultc \ 
FinliCN, Am|>liil)u, :tii(l Reptiles, and arc chamcicmed tijr tbcE 
coKl blood niid imperfect circulation. 'Hie l/amateihtrmt a 
W'ann-Uooded Vdtcbmtes comprise the Ihrds and the )lt» 
mals, and arc characterised by their hot blood, foiir-chambatJ , 
hcan, and complete separation of the pulmonary and systcK | 
circulations. The chief objection to tliis division lies ia ikj 
separation which is effected between the Reptiles and Ikj 
fiirds, t«'0 classes whidi are certainly very nearly allied to sM ' 
another. 

Uy ProfexKor Huxley the Vrrltbma are divided into the \^ 
lowing three primary sections : — 

I. lciiTKYOPSit>A. — This section comprises the Fishes ud 
the Amphibians, and is characterised by the presence at mxm 
period of life of gills or branchiae, the absence of an amnim 
the ah&enoe or rudimentai)- condition of the allaniois, and tk 
potsesnon od* nudeate<I red blood'Corpiucles. 

II. Saurop-^iqa. — '['his section comprises the Itirdi and the 
RcptSe^ and is characterised by the constant alienee of pE^ 
the possession of an amnion and allaniois, the aiticulatioa of 
the skull with the vertebral column by a single occipinl ceo- 
dyle ; the composition of each ramus of the lower jaw of «via! 
pieces, and the articulation of tlie lower javr with the skaO ^ 
the intervention of an " os quadratum ;' and, taitly, the pott» 
sion of nucleated red blood-corpuscles. 

III. Mammalia. — This section includes the single claa of 
the Mammals, and aj(iees with Ihc preceding in never po«B- 
ing gills, and in having an anuiion and allantois. The Jfo- 

* The omnitH <{ij;. 114) i« a inenibnnolu tac, containiiig 1 Sii^ 
llie liquor amiiii — and comTiletcIy eimlapine the embc^poL II cteO- 
tutnone «r th« *o-caI1«t "lorLa] membranes, sad ii Uinxm off aiKiA 
The alUntfii (lig. IZ4. C) ii On cmbirTonic nniclvrc, wliidi n 4e*ti(f^ 
out of th« mlnldle or '"Vlucolir" layci of the j;cnniiUkl Mcaitintae. tl Ip 
pcan &l iini ts a totUI, pdr-Dh-iprd. cellular mtn, arbinK frani the <bM 
part of the \«iAy of <h< embtyo. In the procr>i«f devrlofinKU, the»*» 
toil increi>«t Inntrly in tiie. and brcomts coDvtrtid into ■ retfdt «iid 
eiivclopj the cmbtyu in iiatt or wholly. It it •bnnduKly MpplM*i^ 
blooil, ind ii the orsan whenlir the blood d the fortus is aenld nj 
part «[ Ihc alUntOM which ii otemal 10 ihe bcdv of ih« cnibiyo iioM* 
U binh ; but the portion which U withia the boay ii ictoiuMi, and i> o^ 
verttd Into the unnary bladder. 



DIVISIONS OF THE VEKTEBRATA. 



361 



So, Iiowever, differ from the Sauropstda in the fact that the 
11 aiticulates with the vertebral column by two occipital 
idyles; each ramus of the lower jaw is simpte, composed of 
togle piece, and the lower jaw is united with the temporal 
oamosal) element of the skull, and is not articulated to a 
kdrate bone. There are special glands — the mammary 
ads — for the nourishment of the young for a longer or 
Iter period after birth, and the rwi blood-corpuscles are 
i-nucleated. 



3*2 



DIVISION I. ICHTHYOPSIDA. 



CHAPTER LIV, 

CLASS I. — PISCES. 

The first class of ihc VertArOA is thai of the Fish« (/"■'." 
wfiich may be broadly defined as including yertef-ralr i!iir±' 
tvkieh are prtnidal wHA gills thr\nigheut thr winttf v/ lift, lit 
iuart,wAeH present, ansists {wilh one exaption) of a sitigk Mn^ 
and a sin/(U ventriefe; tAe MW it (^U; the limht, when ftaat. 
are in llu fvrm of fins, or exfoHsifins ef the integument i at 
there is neither an amiu<"i nor aliantm in the embryo^ wtleu A 
latter ii represented /y the urinary Madder. 

In rorm, Fi&lies are adaj>ted for rapid locomotion in «mcr, 
the xliajie of the body beinf; tiucli a.t to give n»e to the la>t 

poiuible frictton in swimming. T« 
Ihijiendnho. uwdlasforpuqms 
of defence, the bodjr a usiulljr O- 
vcloped with a coating of sate 
developed in the inferior or dciad 
layer of the skin. The more i» 
I>ortant modifications in the &n 
of these dennal scales are as fsl- 
lows: I. Cyeitfid >ica.Wn (ft^. [Jt.'l 
^i^^^. Uilllll consisting of thin, flexible,^ 
^Kj^B^ rll 11 Allies, ciratlarorcltiptical in*^: 
^A^^B LJLM and having a more or leu 
^^^Ir I tkl 111 pictcly smooth outline. Tbcv 
^■■^ lllllkl ihf scales which are characieraK 
of moat of the ordinaiy boiiy liite . 
II. Ctenoid scales (fig. ij>. ill 
also con MMii^ of thin honiyfifaM| 
PUcid Kill but having ihcir [wslerior nuisi* 
.ul«.aMtr- f^„g^( „„f, spines. Of cut oB 

coml>-like projections. 1 1 1. Am' I 
Bcales, compoced of an inferior layer composed of bone, conn' 
by a supctficiol layer of luurd polished enamd (the so4*Sri 





(talc d'cnh): c Pluuia tc^ 




CHARACTERS OF FISHES. 



363 



ae "). These scakx (%. 131, 4f) are nnunlty much larger 
Ucker tlian the ordinvy *c.i1m, and thoitgh ihcy arc often 
anicuUtcdto ore anoihrr by spccut processes, ihcyonly rarely 
overiap. IV. yAnwi/tcalcs, consisting of detached bonygrainx, 
tubcrcks, or plates, of which ihc latter aic not uncommonly 
vmed with spines (6g. 13a, e). 

In moat lishes there is also to be observed a line of peculiar 
Kales, forming what is called the " lateral line." F^di of the 
•cales in thin line \* performed by a tube leading dun-n to a 
longitudinal canal which runx along the ^idc of the body, and 
is connected with cavities in the head. The function of thJt 
singular system has betrn ordinarily believed to be that of so- 
creiing the mucus with which the surface of the body is covered ; 
but it sccnis to be more probably sensory in function, and to 
be cocmcctcd witli the sense of touch. 

At rq;>rds their true os.ieinis system or endoHkeleton, Fishes 
vary ^ery widely. In tlie lanceiet there can lunlly be uid to 

i be any ^keIe^on, the spinal cord being simply supjiortcd by 
the ijdatinuus notochotd, which remains throughout life. In 
others the skeleton remains permanently cartilaginous; in 
iHhcrs it is pariblly cartila^iuous and partially osuficd ; and, 
LiMly, in most modem fishes it is entirely ossilted, or converted 
into l>onc. Talcing a bony fish (fi^- 133) as in this respect a 

' typkal examjile of the class, the Mlovring arc the diief jioinls 
in the ottcotogy of a fish which rciiuirc notice : — 

'ITic xfrtfbral a'/umn in a bony fish consists of vcrtebisc, 
which arc bollo«' at both ends, or biconcave, and arc techni- 
cally said to be " amphictclous." The cup-like margins of the 
vcficbral bodies arc united by ligaments, and the cavities 
(i>ttued between contiguous verlcbrai arc filled with the gcla- 

I tuotm remains of the nolochord. This elastic gelatinous sub- 
nance acts as a kind of liall-and-iocket Joint betneen the bodies 
of the vctlel^ra". thus giving the whole spine the estreme mo- 
Wily which is reriuisilc for animals living in a water)- medium. 
The ossification ot the vcrtcbrsc is often much more imperfect 
tlian ihc above, but in no case except that of ihc Bony Pike 
{t^i^initus) is ossification cairied to a greater extent than 
Uii«. In this fish, however, the vertebral column is composed 
of" opisthocoilous" vertebra — that is, of vertcbne tlie bodies of 
«hicJi are concave behind atid convex in front Tlvc entire 
apinal column is divisible into not more than two distinct re- 
gions, an aMifminal oxtA a (OuJa/ rfgion, I'he abdominal ver- 
tebra; |>osscss a superior or neural arth (through whitli iiasses 
Cfac spinal cord), a superior spinous process (neural sjiinc), and 
two ttanavCTsc proocsMS to which the ribs are usually attached. 




364 MANUAL OF ZOOLOGY. 

The caudal ^-crtcbnc (fig. 133) have no roatked traiwitiw p 
cettes; but, in addiilon to the n«ural arcliesaad iptncilbcr 
give off an inferior 01 hama! urch t>eiow the body of ibc Ml^ 
bra, and the haemal arches cany inferior tpinous [cocaa 
(hietnaJ spin«s)i 

The ribi of a bony fish arc attached to the trjiuv«w ii» 
CCS&CS, or to tlw bodies oftJic abdominal vcncbr*, in tbct» 
of slender curved bones which anicuUtc with no nxiM ta 
one vertebra each, and that only at a single point, t'aliktw 
ribs of the higher Venebraien, the ribsdoaot cndo«eail)caK 
cavity, t)ut are sinii>ly embedded in the muscles vhkli beal 
the abdomen. Usually each rib gives o0 a Bpinc4ike t«K 




rif. i)|.— EMclon of Ihe eHBnuHi INnb (nvni^jWMj.iwi. t One it tfK !•'■■' 
lus ; r Oa< af ih* nninl Mm i ■• As>t fin, lUMvnHl upaa taunailBMH Iimb " 
Caudal lini V>'<nldurul fin; rf' Sctnnil JwmI fa. fcWb HHtWol i»t bwnl 
bskh: (/ Inienpininu bgnat rRitiai i Spimnu precsMaaf Wttti*; 1 n 
innHa of vcntbfs. 

which is directed backwards amongst the muscles. \t6c*^ 
the extremities of the ribs arc free, or are rarely united lot)* 
inal os«ficaitons in the middle line of the abdomen ; but tJWt 
is never any brcaiit-bone or sternum [iiopeily so called. 

The only remaining bones coiincctetl with the skeltW" 
the trunk arc the so-called into-fpimui b^nts (fig. i^"> 
These form a series of dafiger-!iha|>ed t>ones iMu^gcd i» * 
middle line of the body between the great laioa) ■** 
jvhich make up the greater [wri of the body of a fi'^'J 
~ "tds or points of the iritcrspinoiis bones are iWtw 

T the spiiiou.t processes of the verttboe; *■■ 
iTi&s aic articiiUlcd the " rays " of the •«* 
, whicli will be hereafter dcccribed. A»»** 
le uuersj>inous bone to each sjiinooi |«f<* 
"8 (Sole, Turbot, Uc.) there wt wo. 



CHARACTERS OF FISHES. 



365 



Bcsi<]e the fii» which represent th« timt» (pectoral and 

Html fini), fishe* powiCK« other fins placed in ihe middle line 

' the body, and all of these alike are supported t>y bony spines 

"rays," which arc of two hinds, termed respectively "spi- 

irays" and "sofl ra)-s," The "spinous rays" ate sim^e 

ny spiiK-s, apparently composed of a single piece each, but 

Jy coflsistiiig of two halves firmly united along the middle 

The *' 8<5t raya " arc coin{>oaed of several slendci spines 

lin^ from a conunon base, and ail divided tmiiKvenely 

Mo nuinerotut short pieces. The .soft niyx ocair in many fivhes 

dilTereot fios, but they are invariably found in the i.iihUI 

, or tail (fig. 133, c). The rays of the median tins, whatever 



•n. 



■■'. 



I rf Oil (Mtrrtma vmfe»riif-Cir<tt. « UmM; # liAl^: f 
I'lMn-upcKulua; mUtafdiMt: ■ [Bi(t-nnllUi)rtwife 

^duntcter may be, always articulate by a hii^-joini with 
of tile inicnjiinous bones. 

■x^/ of the bony fishe* is an enremely complicated 
«nd it is iropoMible to enter into it* composition 
e ooly portions of the sk«ll which rcqmre special 
* liiebona which form tl« KlU^over oroperoUmn, 
yoiri bone with its appendages. For reasons con- 
" Uw mpiratofy process infishw. as wilV\K rfus. 




366 



MANUAL OF ZOOLOGY. 



wards seen, there generally extsu between the bead anil tix 
scapular arch a great cavity or gap on each side, within ■hKii 
are contained the bruichlas. I'hc cavity thus Totnu-d opau 
exiem.-ill)- on each side of the neck by s single vertical dsioit 
or " gi!l-»lit,° closed by a broad flap, called the "gilUowt* 
or "opumilum," and by a membrane termed tlie "bnad»- 
ostcgal merabmnc." 

The giIl<ovcr (fig. 134,/, f,r, »') Is compnsed of a«Stio«( 
bioad Hat bones, termed tlic opcnruUr bones. Of fl 
innermost articulates with the skull (t)-mp.-ino-mandiliu 
andUcallcd the "prx-opcrculum;" the next is a laige Imh 
called the " operculum "* proper ; and the remaining two hooa 
called reipeciivcly the "sub-operculum" and "intcr-opcrnil'ai,' 
form, with the openniliun proper, llic edge of (lie gtll<«i'ei 
Thete various bones are united together by inembtanc. I'-i 
they form collectively a kind of movable door, by means 1' 
which the branchial chamber can be alternately opcDol >»! 
shut. Besides the gill -cover, however, the brsnchial chimlxr 
is dosed by a membrane called the " bnnchiostegal men- 
branc," which is attached to the os hyoides. The memhuM 
is supported an<I si)read out hy :■. number of slender cvmi 
spines, vrhieh are attached to tlie lateral branches of the hjvl 
bone, act very much as the rib* of an umbrella, and arc iKm 
as the " branchiostegal rays" (iig. 134, rf). 

The hyoid arch of Ashes is ;tti3c^ed to the temponl booet 
of the skull by means of two slender Myliforra bones, "twi 
correspond to the styloid processes of man, and are callid tk 
"stylohyal" bones (fig. 135./). The rest of the hyoidartka 
composed of a central portion and two lateral brandies, f-"^ 
branch is composed of the following parts: — 1. A triango^ 
bone attached above to the Mytohyal, anil termed the "epibri' 
bone" (fig. 135, f); 2. A much longer l)one, known as iW 
"ceratohyal" (rf). Tbc central jjortion of (he hyoid aith » 
made iii> of two smalt i>olyhedra] bones — the "basihyalt'J^) 
from trie baxihyal there extends f&ntiards in many &thci t 
slender bone, which supports the tongue, and is termed ^ 
"glos!ohy3l"or "hngual" bone (u). There is also anolhf 
compressed bone, which extends liatheardi from (lie btutpit 
and which is known as the "urohpl bone" (<*). ThtsHi 
mentioned bone is of importance, as it often extends h^P 
war«U to the point of union of the eoracuid bones, anil IM 
forms the isthmus which separates the two branchial apernim 
From the "utcr mar)cin» (ffthe epthjal and reratoliyal h**' 
on each side arise the slender cut\ cd " bmnchtostcgal »^ 
which have been vKvioucty mentioned. Tliere arc uw 



CHARACTERS OF FISHES. 



3«7 



of Ui«se on each side. Above the urohyal, snd attached 
m frOQi of ihc body of the os hyoidcs, is a ch&ln of bones, 
placed one behind the other, and lenned by Owen the "ban- 
Imnchul bonn." Springing Irom these are four bony arches 
— llie " branchial archn " — which proceed itiiwatdti to be ron- 
nolctl siipcrioily by ligament with lh« under surface of tlie 
tkxiH. The branchial arche« — as will be stibscqiienily de- 
ibcd — cjrr^- the branchiic, and each is composed of two 




■ jt— Oi hrsidn^ WancliIaiMcil ny^ and vipulat u(h (rf the Ptrcl, (untr 
imn\ M ' r|i« »(»Btfi ; i )i<*i>uU; trConntiAl <l SuppoBil nproailalm of 

Klain rkces, termed respectively the " ccrsto-branchial " and 
*' ci>i'lir3n4:hial " bones. The .second and third an hts are coB- 
ttected with the slctitt by tlie inlervenlion of two small tones, 
*ftcn called the " nipctior phar^n^-cal bone*," but lermed by 
Owen the "iJiaryngo-branchial" bones. 

Tlte Hmbf of lishcs depart considerably from the (ypiral form 
J^Xbilnled in the higher Vcrtebraies. One or both pair* of 
*<x»bc may be wanting, but when {^resent the limbs uc alirvj^ 



368 



MANUAL OF ZOOLOGY. 



in the form oijins — that is, of expanuons of the in 
strengthened by bony or caitikginous fin-tay& The »M 
limbs are known as the patoral fins, and the pottaiort 
ventral ba&; and they are at once distinguished from A 
called "median" fins by being always symmetrically (fi^ 
in pairs. Hence they are often spoken of as the fawii 
The scapular arch (figs. 135, 136) supporting the pee 





Gp£en. 



limbs is usually joined to the skuH (occipital bone), and c 
sists of the following pieces on each side: — i. The Wj 
scapula {ss) ; 2. The scapula (s), articulating with the fern 
and, 3. The coracoid (co), attached above with the scapuli,! 
united below, by ligament or suture, with the coracoid rf 
opposite side, thus completing the pectoral arch. Li^tl;, tl 



CHAHACTERS OF FISHES. 



369 



another bone, sometimes single, but oftencr of two 
ices, utachcd to ihc uf^r end of the coracoid, and this is 
Itevcd to Tcprescnt the collar-bone or clavicle.* 
The fore-limb possesses in a modilicd fonn most of l)ie 
incs which are present in the higher VertH-rala. The kum- 
w, or bone uf the u|)|>er arm, is usually wanting, or it i.t alto- 
itber rudimentary. A nidiu.s ami ulna (fig. 136, r, ») arc 
inlly present, and are followed by a variable number of 
Wcs, whkh represent the carpus, and some of which some- 
pics aiucutatc directly with the coracoid The carpii.t is fol- 
Nnd by the " rays " of the fin proijer, these representing the 
Kttcarpal bones and phalanges. I'ne pectoral linx vary much 
I iUe and in other cKanciersL In the Flying Gurnard (Dac- 
l^taw), and the Inic Flying Fish {Exixectut), the pectorals 
t enormously developed, and enable the fish to take exten- 
^ Icapa out of the water. 

The liiivd-limbs or " ventral fins" are wanting in many fishes, 
A they are leu developed and lest fixed in poution than are 
nMCtonI fins. In the ventral fins no Representatives of the 
Sux, tibia an<I fibula, or femur, are ever (leveiupe<L The 
% of the ventral lins — representing the metatarsus and the 
tlangcs of the toes — unite directly with a pelvic arch, which 
sonposed of two sub-triangular bones, united in the middle 
B and believed to represent the isthh. The imperfect pelvic 
thus constituted, b never united to the vertebral column 
ny fiih. In those fishes in which the ventral fins are 
linal" in position (/.£, placed near tl)e hinder end of 
^body) the pelvic arch is suspended freely amongst the 
In those in which ilie ventral fin* are " thoracic " or 
' (/.fc, placed Ijenealh the jwcloral fins, or on the 
I of the neck), the pelvic arch is attached to the coracoid 
of the scipular arch, and is therefore wholly removed 
I its proper nrtcbra. 

1 additioD to the pectoral and ventral fins — the homologucs 
the limbs — which may be wanting, fishes arc furnished 
itfi <:enain other expansions of the integument, which are 
lian " in position, and must on do account be confounded 
ilhe true "paired" fins. These median fins are variable 
umber, ami in some cases there is but a ungle fringe 
Diog round the poMerior extremity of the body. In oU 
, however, the median fins are " aiiyBoti.i " — that is to Bay, 
occupy the middle line of the body, and are not sym- 

(TImm are the view* enleiuineil by Oveo ii to Die compoiiiion and 
0^ tbw pec(ar»l arch of fuhet, twl Ibqr «e diucnitd bwn by Ht 
one of the ptatcBt living niuhontlet on tliit tubjcci. 
3 A 



370 



MANUAL OF ZOOLOGY. 



meoically disposed in pain. Most rommonly, the 
fin.t consist of one or two expansions Qf ihc dorstl iDtegium; 
called the "dorsal fins''(fi^ 137, 4 d^)\ one or (wo 00^ 
veotial suriace Deai the utus — the " anal fins" (6^. t J7, a); ml 




Fig. I]}.— Oul^n^ora <l>h(/Vmi/n*i>f*yH)L ihviHnf ihtralrcd Md miiilH* >■ 
/OiicorilKiwiunilhM: a Ui» of IhcvtaMl fiwi ^fW daoallbi VSnrf 
danal fin ; d Anal Ad ; f Caudal tn. 

a broad fin at the cxtrcmily of the venebral column, allied de 
" caudal 6n " or tail (f). In all cases, Ihe raj:^ which wppst 
the median fins arc articulated with the ito-calted intcrapmoa 
bones, which have been pTcvioUsly deHcnlwd. Though uM 

" median," liom their poeilioa ii 
the middle line of the body.aad 
from their being tin|iatted, tbt 
median fins of Fishes, as sbon 
by (Joodsir and Htmiphrej', K 
tnily to be regarded as formed bf 
the coalescence of two laieal (l^ 
ments in the mesia] plane of ibe 
body. 

The caudal Tin or tail of Ibba 
i!t always set vertically at the c» 
tremiiy of the spine, so as to «t^ 
from lide \o side, and it b ih 
chief organ of progression in ifv . 
lishcs. In its vertical position, la' f 
in the possession oS fin-nys. * 
rij. tji-Tiiiij of differtcrt fi.w differs aitogelher from the boo- 
$ HouwRii tiii <su.nr»n). zontal miegumentary exixuan 
which oon9.tituteN the tail (4'lW 
^^lialcs, Dolphins, and Sirfnia (Dugong and Manatee)- 1* 
(Jic form of ihc tuH taWs ciXv^Jvt. v««i \<x\ diatiiict lypct ^ 





H CHARACTERS OF FISHES. 37 1 

Hined respectively the " homoceraJ " and " helero- 
P& of tail (iig. 158). The homocercal tail h the one 
ist commonly occurs in out mcxJem tishet, and it is 
Ised by the fact that the two lobes of the tail are 
ii the vertebra! column, instead of being prolonged 
upper lobe of the tail, stops short at its base. In 
MTCTcal tail, on the other Iwnd, the vertebral column 
;cd into the upper lobe of the tail, so that the tail 
uncqualty lobed, m greater portion being placed 
' spine. Even where the rertcbnl column is not pro- 
to the upper lobe, the tail may nevertheless become 
ml, in consequence of a great ijevel<)i>meni of the 
pines as oomiMred with the nciinU »|iiues of the 

ocess of rfsfiimtifitt in all fishes is essentially aquatiCi 
rried on by means of bmnchiol plates or tufts dcvel- 
n the posterior visceral arches, which are pcrsbtcot, 
X dtnppcar at the close of entbryonic life, as they do 
Vertebrates. In t)ic I.Ance1et nione, respiration is 
xutly by branchial hlamcuts placed round the com- 
nt 01 the pharynx, and partly by the phar>-nx iuetf, 
greatly enlargct). ^nd has its walls perforated by a 
transverse ciliated fissures. The arrangement and 
of the branchiie differ a good deal in the different 

Fbhcs, and these mollifications will be noticed sub- 
In the n)eaiiwhile it will tie sufficient to give a 
riplion of the branchial appiiratu.i in one of the bony 
B such « fish, the branrhia:: nri: connected with the 
h, Mid ore situated in two special chambers, situated 
Mkch side of the neck. The branchix are carried 
outer convex sides ofwhat have been alrctdyiJc^cribed 
>ranchial arches ;" that is to say, upon a scries of bony 
uch are connected with the hyoid arch infcriorly, and 
d above with the base of t)ic skull. The internal 
■ides of the branchial arches are usually furnished 
ties of p(oce»et, constituting a kind of fringe, the 
3f which \* to prevent foreign substances finding their 
igat the branchix, and thus interfering vnth the proper 

the respiratory organ.*. The branchiic, themselves, 
ive the form of a double scries of cartilaginous leaflets 
C The branchial lamina: arc flat, elongated, and 
a shape, and they arc covered with a highly vaacubr 
ncnbrane, in which the branchial cipillarics ramify, 
d drculatn through the branchial lamina.-, and is here 
itethe utiom of Krated water, wbcicby *U u qvj^cw- 




"» ttnniir completed 
Ibc "bwnchiostqpl 



rays"- 
1 




'*■. I»— DiiBMm of iht ri^ 



UStUI 

The, 
with 
fibre 
traits 
cases 
ooniL 

The I 

throuj 




Tt, but is drivGn from lh« t>ranchi» Uirough all paru or 

bwiy ; the piopuhive force neceswry for Ihij bcina derived 
cfly from ibe heart, nssUicd by the contractions of inc volun- 
t muscles. In some lishcs (as in the VaA) the return of the 
od to the heart is assisted by a rhythmically contractile 
UUion of the caudal vein. The essential peculiarity, iheii, 
lie circulation of fishes depends upon this — that the arte- 
bed blood returned from the ai[\% is propelled through the 
temic rcssds of the body, without being sent back to the 
in. 

n»c Lancclct {Amp/iioxus), alone of all Fishes, has no 
cai heart, and the circulation is effected by contractile 
mtions developed upon several of the blood-vessels. In 

Mud-lish {/jj^ufi'siren) the heart consbt* of two auricles 
1 a sin{,de vciUride. The blood- corpuscles of Fishe^ are 
Jeated (fig. 13a, e\ and the Mood is red in all except the 
tfiAiaxui. 

u regards the i/igatirv sjstfm of Ft&hcs there is not much of 
iiltar importance. The mouth is ui^ually fumi^ed with a 
oplioued scries of tcetti, which, in the Bony Fisho, arc not 
ji det-elopetl U)>on the jaws proper, but arc also situated 
m Other bones which enter into the composition of the 
Xal cavity (such as the palate, the pterygoids, vomer, 
nchial arches, the glossohyal bone, &c.) The oesophagus 
■oaJly sbon and capacious, and {:eneiaUy opens into a targe 
I mU-matked stomach. The pyloric aperture of the stomach 
iMially furnished with a valve, and behind it there is usually 
umber (froro one to slKty] of blind appendagei, termed the 
ylonccxca." These arc believed to represent the pancreas, 

there may be a recognisable pancreas either alone or in 
lition to the pyloric ca;ca. The intestinal canal U a longer 
ihoncT, more or IcsS' convoluted tube, the absorbing surface 
which, in certain Inhcs, is largely increased by a spiral 
uplicature of the mucous roemt>rane, which winds tike a 
•w in cloic turns from tlie pylorus to the anus. The liver 
Jly large, soj't, and oily, and a gall-bladder is almost 
lly prctent ; but in the AmfAiAvut tlie liver is doubt- 
:|)reMnted by a hollow sac-lilce organ. 

he kidneys of hshcs are usually of great sixe. and form two 
ngated organs, which arc situated beneath the s(>ine, and 
Rid along the whole U-nstli of the abdominal cavity. The 
tcrs often dilate, and form a species of bladder, the doubtful 
resentative of the allantois. 

A^ilst the respiration of nil fishes is truly aquatic, most of 
Bi utf ncvcTtheleu, furnished with an organ which it 




J74 MANUAL OF ZOOLOGV. 

doubtless the homologue of ihe lungs of the air-bnattcf 
Vertebrates. This— the "wr" or "swim bUdder"— is » « 
containing g^is, situaled benexth the alimentu)' iabc, ■£ 
ottcD comiuunicating with the gtillct b/ a duct In the ^ 
majorily of fi&hes the fuoctions of the air-bladder vc cttiati 
hydrostatic — that is to say, it serves to maintain the neccst} 
accordance between the specific ({raviiy of the fish aod ihK « 
the Jturrounding water. In the singular Mud-lishex, bowRtt j 
it acts Its a respiratory or^an, and is therefore not oolf tk | 
hotnologue, but also the a»:ilogue, of the iun^ of the higto j 
Vertcbrstcs. In most fishes tlie air-bladder is aa clocpu' 
sac with a single cavity, but in manv cases it is variouilf «fr 
divided by septa. In the >iud-lish tlie air-bladder is conip*^ 
of two sacs, completely separate from one anoiher. and ilin)^ 
into a imm1>er of cellular compartments. The duct kadiig i> | 
many tishea from the air-Uadder {dtKtut fnmfitatum) ■ 
into the (Ksopha^t, aitd i^ tlie homologue of the 
{trai/ua). The air contained in the swim4>laddeT is < 
mainly of nitrogen in moM fresh-water Ashes, but in 
6shcs it is mainly made uji of oxygen. The fishes wh 
habitually at the bottom of the sea, such as (be FUi-il 
possess no swim-bladder, and it is much reduced in 
those which live principally at the surface. 

Ilie ntnwit syittm of lishes b of an inferior tjrpc of txp^ I 
iiation, the brain being of small siie, and consisting nuink^ 
ganglia devoted to the special tenser. As regank the s|xpJ 
senses, there U one iieculiariiy which deserves mcU ^''^l 
snd this is the conformation of the nasal sacs. The atiiT* | 
the nose is usually double, and is lined by an olfactoiy i 
btane, folded so as to form numerous plica;. Anteiio' 
vrater is admitted into the nasal sacs by a single or 
nostril, usually by two apertures; but posteriorly the: 
sacs are clo.ted, and do not communicate with the 
by any aperture. Tlie only exceptions to this statco 
to be found in tlie Myxinoids and in the LqiJdonreo. 
eueniial portion of the organ of hearing (lafyrinlA) i» pK^] 
in ahno»[ all lishes, but in none is there any direct coniB* 
cation between the car and the external medium, la f' i 
cases, however, there is a communication between the ea >• 
the swim-bladder, thus foreshadowing tlie Eustachian ctbe * 
man. 

As regards their reprofiwikt system, fishes are, for the v^ 
part, inily i*t<i^iri'us, the ovaries being familiarly knO«B »* ijf 
" roe." The teste* of the male are commonly railed ilw '^ 
n>e ■' or " milt," The products of the reproductive oigM**' 



CHARACTERS OF FISHES. 



375 



often set &ee into the peritoQeal cavity, ultimately finding their 
way to the external medium, either by means of an abdominal 
pore (or pores), or by being taken up by the open mouths of 
the "Fdlopian tubes." In other cases the generative pro- 
ducts are direct!}' conveyed to the exterior by the proper ducts 
of the reproductive organs. 



376 



DIVISIONS OF FISHES. 



CHAPTER LV. 

PHAftYNGOBRANCHSI AS'D MARSIPOBRANCIUI 

Thb class ris<f4 lias been very variously subdivided by d* 
fcrent writers ; but the classification here adopted is tbc ont 
proposed b^ I*rofcssQr Huxley, vbo divides the class tnio tie 
following EiK orders, in the subdirisioos of which Profb« 
Owen has bccD followed : — * 

Order I. Pkarvnoui:sanch[1 {^ = Cirrtttomi, Owen;i]id 
Ltpleau^ia, Miiller). — Tliis order includes but a single iiHt, 
the anomalous Am/Aioxut lanttolalus, or I^ncelct (6g. tjoli 
the organisation of nhich ditTers in almost all important (mibh 
from ih.-il of all ihe other monbcrs of the class. The order > 
defined by the following chaiacteis, which, as will be seen, m 
mosily negative : — No skull is present, nor lower jaw {manditiet. 
nor limbs. I'he noiochord is persistent; and there are m 
veitebral centra nor arches. No distinct brain nor audita; 
(»gans are present In place of a diKlinct heurt. pulsating <bl^ 
tations are developed tijion several of tlie gro.it blood-t-asetL 
The blood i« pate. 'I'he mouth is in tlie form of a longituibial 
fissure, surrotindcd by filaments or cirri. The w^b of iht 
pharynx arc |)crforatcd by numerous clefls or fissures, llu 
sides of which arc ciliated, the whole excrcisinj; a res|iaatC(T 
liinction. 

I'he Lancclct is a singuUr little fi^ which \a found buner 
ing in sandbanks, in vniious seas, but especially in the Vi^ 
tcrranean. The body is lanceolate in shape, and is pro>id(d 
with a narrow membranous border, of the nature of a mccbt 
fin, whidi runs along the whole of the <lors3l and pan cf ibt 

" Cuiricr ilivWrf the clan Pitta into the pt« ordcn of the CU^f 
teryp'Hm Cini%inous Fiihn), the AntHlJ^fitiyrii (or Fiilx* wilk iskn 
cayt in tbc paircH lini). and .IMaivfiUngii for Flhbct wllh mR ni< 
ill the ruurtd liru). .\cBuii dtvUlet Ficho, iroan ihc cliantctrr I'l* 
KalM, Into the four «iden, Cwltidti, CtrifUfi, GnwvJti, ud FUai^ 
Mutler dlHJM (h« Flxhe* into Iho niw orrlcn Uflteardia <Lanod«t|. Cf^ 
flVmdM (Lamprey* and Hftg-ribbnl. 7>ihiwft»*(BoayFUhei),<7iiNMht(Cit^ 
FithesJ, and Sdathia (Sharks and Rajrv), 




PHARYNGOBRANCHII. 

Ci Mid exp.ii)il!i nt the tail to form a lancet-shaped 
lal fin. No true i>airc<l (ins, rei>menting the anterior and 
erior limbs, arc present. The mouth is a longiiuditu] 
K, Mtuaicd at the front of the hc.id, and destitute of 
I. It is surrouDded by a canibginous ring, composed of 
ly pieces, which give otT prolongations, so as to form a 
iber 0^ cattlUginous filaments or "cirri ' on each side of 
mouth. (Hence the name of Cinvitomiy proposed by 
^BGOr Owen for the order.) 'Hie ihroat is provided on 
r side with vascular lamellse. which arc believed by Owen 
Bform the function of free branchial filaments. The mouth 
h into a dilated chamber, which is believed to represent the 
lynx. and is lenncd the " pharyngeal " or " branchial sac" 
I an elongated chamber, the walls of which are strengthened 
Htmerous cartilaginous filaments, between which is a series 




^)^— Pucnmii'tTie tdncielfl (.^la^^u) m Uouth, lurroitailed by onilA- 
1 1 iiHiljr-dlUod twrnn. iwlanHd by i;iisial rkfta; t iMttiiet, 



tuisvcrse slits or deAs, the whole covered by a richly eili> 
t mucous membrane. This branchial dilatation luu given 
m tlw name Smukieitoma, often applied to the LanceleL 
leriotly tlie branchial sac opens into an alimentary canal, to 
t^ is appet>ded a Ions and capacious sac or caecum, which 
Iwved to repretciit the liver. The intestinal tube tcrmi- 
posterjorty by a distinct anus. Rcspir^ktion is effected 
Qc admission of water taken in by the mouth inio the 
aial sac. having previously passed over the free branchial 
ats before mentioned 'liic water [xisses through the slits 
branchial utc, and thus gains access (o the abdominal 
y, frmn which it escapes by me;\ns of an apetluie with 
■aile inaruinx situateil a little in front of the anus, and 
ed the "al»dominal itorc." There is no distinct heart, and 
circulation is entirely effected by means of several rhythmi- 
f coDHactilc dilatations which are developed upon several 




378 



UAKUAL or ZOOLOGY. 



of the great blood-vessels. The blood itself is colouiksfc ^ 
ktdnc>-B have as yet been discovered, and there is do Ijnphiac 
systoa There is no skeleton praperijr to called. In pbccd 
the vertebral column, and consiiititiiig the whole cndoikdfln. 
it the aenu-gcUiinous celluUr aoiochon!, enclosed in a ihno 
sheath, and K'^tng oS fibrous archei above and below. Tk 
notochord is, runher, ];>eculiaf in this, that it is nrolocgedqaK 
to the anterior end of the bodjr, «rherca:( in all other VertcbnlO 
it stops short at the jMluitary fossa. There is no cnj)iMii,nd 
the spinal cord docs not expand anteriori)r lo lomt a disBid 
cerebral mass. The brain, however, may be said to be re;ff 
senied, since the anterior ponioit of the nervous axis ^vaaf 
nerves to a pair of rudimentary eyes, and another branch toi 
ciliated pit, believed to represent an olfactory organ. ?W 
generative organs (ovaiia aiMl testes) are not rumii^ rd 
any cffereni ducH (oviduct or vas deferens). The gencrUnt 
products, therefore, must be admitted into the abdooail 
cavity, and gain the cxteraol ntcditim by the " obdoanl 
potc." 

Order II. MARStPOiRAXCHli ( - CyfAutMM, Owen ; ai 
QnUitima/a, Mullet). — I'his order inctudex the Laioftrp 
{Fttrvmywniiia) and the Hat;-fishes (Mjxinida), aitd is dcEMJ 
by the following characters : — llie bo<ly is cylindrical, wonfr 
like, aiKl destitute of limbs. 1'he skull is cartilaginous «iib- 
out cranial bones, and having no lower jaw (mandtbleV Tie 
notochotd is persateni. and then: arc cither no vcnebnu mm, 
or but the most rudtmemary traces of them. The heart consB 
of one auricle aivd one ventricle, but the bnuchial artery is nM 
furnished with a bulbui aneriosus. The gUts are sac-hkc. lod 
arc not ciliated. 

The type of piscine organisation displayed in the Manif^ 
trofuAii is of a very low grade, as iiidiralcd chiefly by At 
peratMcnt notochord withonl venebnl centra, the absenettf 
any traces of limbs, the absence of a Duutdible, and the itrsc- 
turc of ibe gills. 

Both the Lampreys (6g. 141, A) and the Hag^fidies arc nr 
tnifonn. eel-Hke fishes, which agree in possessing do ptftd 
fins, 10 represent the limbs, but in having a median fin ttaoK 
round the hinder extremity of the body. The akeleUi n 
mains throughout life in a cartilaginous condition, the cbinh 
dorsalis b persistent, and the only traces of bodies of vcrlrio 
are fouttd in liardly perceptible rings of osseoos malier <h 
vclo{>ed in the sheath of the notoch«d. Tbe neural anhai' 
the vcrtebnE, enclosing the spinal cord, are only reptncoKd 
by canilaginous prolongatioas. The mouth in the Ha^ 



UARSlPOBRANCItli; 



379 



)fj/xiiu) is of a vcr)- remarkable character, and enables tt to 
'\ ft var peculoi mode of life. It is usually found, namely, 
Idea in tlte interior of some other large &sh, uito which 




ai^ht fjlMe^ B, Di^Bnv ID iUu»tf&<e Elbe Kructurc trT ilie cUU Id the L^uuprav; 
■• riniTHm 4 T<4* laMlBC fivn Eh« pharjni inu on* •iJiIh (fll-Hal f Onr <il th* 



ID !tlu»tf&<e UI4 Kructurc Zt the cUU in the Linpray 



git tm^ (tn nuiiy ll>« flill'M^ do h«i cnco diivnly into rh« pKi/rii** bui iaio a 
■■■MM If liilmi iiiln. which b flidCMa ru ih* Bb QTcluniuL 

it has succeeded in penclratinf; by means of its singular dental 
appamtua. The mouth is sucker-like, destitute of jaw.^, but 
provided urith Uctilc lilaments or cirri. In the centre of the 
palate is fixed a single, large, rccuned fang, which is Crmly 
stUched lo the undcf suilkcc of the cranium. The sides of 
this fang are stroflgty serrated, and it b by means of this that 
the Hag-fi&h bores its way into its victim, having previously 
attached itself by its sucker-like mouth. In the I^uinjiteyx th« 
iDouth has also the fonn of a circular cup or sucker, and is 
also destitute of Jaws ; but in addition to the paUtine fsng i>[ 
&t Myxme, the nurgin» of the liju bear a number of homy 
pnceues, which arc not really trMc tcvth, but arc hard struc- 
tures developed in the Uhial mucous membrane. The tongue, 
also^ is arTn<.-d with scrntled teeth, and acts as a kind of piMOD; 
M that the Lampreys arc in tliis manner enabled to attach 
thcnu«lvcs fiimly to solid objects. 

A very renuritable peculiarity in the Hag-fikhes, and one 
very neeetiian' to remember, it found in the structure of the 
mmI Hca. In all fishes, namely, except thcKe and the Mud- 
6she> {Ufidatirai), the nasal sac-n are clo»^ behind, and do 
not open (Kxrieriorly into the threat. In the Myxinoids, how- 
crcT, such a communication exists, and the nasal sac — for 
there is only one — is placed in communication wiUi the cavity 
of the mouth by means of a canal which perforates the palate. 
In front the nasal cavity communicates with the l^xte^)al me- 
dmm by a second tube, whicli opens on the top of the head 
by a single aperture, whidi is ol^D called the " ayuidi:^' uA 




380 



MANUAL OF ZOOLOCV. 



which i« in reality an iiiipaircd noittriL In the Lam, 
the other hand, the single iiumI Mic his ihc same suucnn at 
in the typi<:a) fishes — that is to »y, it is closed behind, tai 
docs not cotnmunicjttc in any way with the C3\'ity at tlie inouii 
Another very remarkable poini in the Hag-fulto uut Lw- 
preys is (o be found in the stnicture of the gilts, from vhidi 
the name of the order is derived. In the I jjniweys, in fbct 
of the single gilt-slit, covere<1 by a gilt-eovcr, as sc«n in 
ordinary bony Ashes, the «de of tlie neclc, when viewed . 
temnlly, exhibits six or seven round holes placed ^ bad in 
line on each side {f>g- 141, A). In the Hag-lishc^ the exi< 
iipertfjrcs of the gills arc reduced to one on each side, 
below the head ; but the intcnial stnictute of the gills b 
same in both cases. In both the Lampreys and the Hag 
namely, the gills are in the form of ucs or |>otHJic» (fig. 141. Kl^ 
the mucous membrane of M'hich is thrown into fokis or ' 
like the leaves of a book, over which the bianrhial v 
ramifv. InlcmAlly the saes eommuiitcaie with the Ofily 
the phamyx, cither directly or by tht; intervention of a cofniMa 
respmtory tube. It follows fmm this, that the (;ill-|>oucbct oa 
the two aides, with their included fixed branchiaJ Liminx, coa- 
municate freely willi one another through the pharynx. 'IV 
object of this arrangement appears to be mainly that of ob» 
ating the necessity of admitting water to the gills through the 
mouth, OS is the oat with the ordiniir}- bony fiKhes. TbW 
fishes are in the habit of fixing thenuelvcs to foreign ohjtot 
by means of the suctorial mouth ; and when in this poation, i: 
is, of course, impossible that they can obuin the ncoetiUT 
water of respiration through the mouth. As the bnwchiij 
pouches, however, on the two sides of the neck, comnwaioK 
freely with one another through the pharynx, water can readh 
pasi in and out This, in i}\c Lampreys, is further assida 
by a kind of elastic cartilaginous franicKork ujion which Ibc 
respiratory apparatus is supported, and which acts somcvlM 
like the ribs of the higher I'frtdralii. Water can also be 
admitted to the pharj-nx, and thence to the branchial soci, If 
means of a tube which leads from the phsiynx to an a|)cnutt 
placed on the lop of the head. 

Tlie Lampreys are, some of them, inhabitants of riven; M 
the great Sea-lamprey {P^itvmyum mahuus) only t\mV. Ac 
salt water in order to s]>awn. The mouth in ine Ptln^ 
aonida. is a circular cartilaginous ritig, formed by the inul|f» 
mation of the palatine and man<libitlar arches, and canyiM 
numerous teelh .ind small mbercle*. The tongue ii smA 
with a double series of small teeth, and acts like a pinoOi 




TELEOSTEI. 

ftbling the animal to atUch itself to slon«s and rocks. Th«r« 
h no air-bU(!(icr. The body is cylindncal, compressed towards 
the tail, ind destitute oT scales. The skeleton consists of* 
Krics of canil:i(^nous rings without ribs. 

In the MyxiniJte the mouth is circular, inembnnous, with 
eight cirrhi. The palate canio: a sinf^te haf,, and the tongue 
b aimed with it double row of small teeth on eaiJi side. There 
BMy be lercn branchial apertures on each side {Jfeftatrema), 
or the twanchiAl pouches open into a common tut)e on each 
ndc.and each of these leitninatcs in a. distinct aperture situated 
under the heart on the lower surface of the body {Gastr9- 
hvwAui). The Hags pour out so much mucus through the 
lucnl hne that they can surround themselves with jelly; hence 
Ihe name of tJie common s]jecies {Myxine glulimm). The 
Dlutinoiu Hot is a naiivc of the North and lintitJi seas, and 
I thit6y found in the interior of the Cod and Haddock (often 
hre or six individuals to one fbh). 




CHAPTER LVI. 

TELEOSTB/. 

•RDER III. TeLKOSTEt. — 11)18 ordcT includcs the great ma* 
nity of tuhes in which there is a wetl-ossified endoskcleton, 
Ad tl corresponds very nearly with Cuvier*! division of the 
osseous " fishes. The Televtfei are defined as follows ; — The 
ccleton is usually well ossified ; the cniniuni is j>rovi<ted with 
nuiial bones ; aud a manclible is present ; whiht the rertelMraJ 
otuinn almost always consists of more or less com]>letely ossi- 
ed vertebrae. The pcctor.il arch has a clavicle ; and the two 
ain of liiatxi, when prescnl. arc in the form of lins supported 
y r»y«. 'ITie gilU are frit, pectinated or tu^ed in shape; a 
ony gilJ<ovcr and braochioileKAl rays being always dcvel- 
pea. The branchial artery has its base develojied into a bul- 
ttS arteriosus ; but this is never rhythmically contractile, and 
I sepanted from the ventricle by no more than a single row 
f vuves. 

The order TeUcitei comprises almost all the common fislies ; 
nd it will be unnecessary to dilate upon their stnicture, as 
bey yen uken as the tjpcs of the class in giving a general 
csaiption of the l-'ishcs. It may be as well, however, to rccapt- 
tlote very brielly some of the leading characters of the order. 



iSa 



MANUAL or ZOOLOGT. 



I. The tkeUten, instead of remaining throughout life 

or less completely caitUafincnK, is now always more 

thoroughly OMifieil. The iioiochord is not pem&tcnt, and the 
veriebral column, tlioii^h Kometimes canilafpnous, consists t&i 
numljcT of vcrtebrx. Thv tHxitex of the vertebrne aie what ii 
ctllccl " amphicccloiis " — th.nt is lo ay, they arc concave u 
both ends. It follows from this, that t>«l«-ecn each pair d 
verlcbnc there is formed a doubly -conical ca^'ity, and ctii it 
filled wilh the cartilaginous or semj-gclatinous remains of tbc 
noiochord. fiy this means an extraordinary amount of An- 
bility is given to the entire vertebral column. In no fish emft 
the Bon^ Pike (which l>e!ongs lo the order Gtuwida) is t^ 
os«iti<3t)on of the vertebral centni carried furtlier than Ibis 
The iikull it of an extremely complicated nature, being to» 
poted of a number of distinct cranial bona ; an<) a minddle 
or lovfcr jaw is invariably present. 

II. The anterior and posterior pairs of limbs are usaallfilpl 
not ain-ays, present, and when developed they arc almp s 
the form of hns. The fin» may be supponcd by " spinoui'v 
"soft" rays, of which the former are simple undivided tpins 
of bone, whilst die latter arc divided Iransversclv itlto I tRB- 
bcr of short transverse pieces, and also are broken up inio ) 
number of longitudinal rays proceeding from a cootaoi 
root, (TTic Fishes with soft rays in their paired fin* m 
termed "Ma!aa>plerypi" — those with spinous rays, "^ilM- 

III. Besides the paired fins, repiresenttag the limbs, lli(Ri> 
a variulile number of unpitiretl or axygous integumeWai; t» 
panxions which are known as the " median fin*" When i^ 
dcveb]n-<l (fig. 137), they consist of one or two fim oo 6c 
back — the "dorsal" tins ; one or two on the ventral TOffacfr- 
tlie " anal ' fins ; and one clothing the postcrioi cKtrrmily if 
the body— the "caudal" fin. The caudal fin is set 

and not horizontally, as in the Whales and Dolphins ; 
the bony lishes its form is " homocercal " — that is, it cotsaa ^ 
two equal lobes, and the vertebral coltiron is not ixokuift' 
into the superior lobe. In all the median fins the fin-rays M 
su[>]>oned upon a scries of dagger-shaped bones, wlwi i» 
phmgcd in the flesh of the middle line of the body, and at 
Attached to the spinous processes of the rcrtcbnc Theft tB 
the so-called "interspinoiis" bones. 

IV. The ktatl consists of two chambers, an auride isdt 
ventricle, and the branchial artery is furnished with a bt^tni 
arteriosus. The arterial bulb, however, is not furnished viibl 
special coat of atriaied muMular fibres, is not thythmicallr oc^ 



TELEOSTEI. 



383 



tile, and » separated from the ventricle by no more than a 
low of valves ^lig. 14a, A). 




14s.— A. Htan a( At JkafUt Itf/iiltr fiunifiia). B, AHcriil hilbof 
I* <£</ulHCnii) nil mtvii. t;, itiMiof tM auaa, (lti>«d WiltniaLlv ; » An 
rtolrUk i * ArHrbl bulb. 



Unnjr 
Auhclflj 



I VtolrUk 

T, The mpiralory orgam consist of free, pectinated, or tufted 
nchix, nittiatcd in tno brstnchial ch:imbcTS, each of which 
BRiunicatcs inlemally with the pharjnx by a series of cldts, 
'ind opens externally an the side of the neclc by a ^inj^le aper- 
ture (or "gill-^il "), which is ]>rotec[ed in front by a buny gill* 
cover, aiKi is aUo closed by a " branchiosiegaJ racmliranc," siip- 
,)>orted ujjon " briinchioslcgal ray^" The bninchi% are xtlarhed 
'to a KXMS of bony branchial arches, which arc connected in- 
fieriody with the hyoid bone and stipcriorly with the skull ; and 
the water required in respiration is taken in at the mouth by a 
procc&s analogous to swallowing. 

VI. The nasal sacs never comniiinicatc posteriorly willi the 
cavity of the pharynx. 

The sutKlivitions of the osseous fifties are so numerous, and 
tfiey contain w> in.iny families, that it will be sufficiCTt to run 
\ ever the more important sub-orders, and to mention the more 
bmiliar examples of each. 

Si;iMiRDER A. Maejicofteki, Owen { = nysostomata. Mill- 
1m). — This sub-order is defined by usu^ly posaessing a com- 
plete set of fins, suppoiicd by rays, all of which arc " iofi " or 
nany -jointed, with the occasional exception of the first rays in 
Ihe dorsal and pectoral fins. A swim bladder is always present, 
>nd always communiaites with the (esophagus by means of a 
duct, which is the homologue of the windpipe. The skin ts 
f^ely naked, and Is motity furnished with cycloid scales; but 
"» some cases ganoid plates ate present, 
.This sub-order is one of great importance, as comprisbg 




384 



MANUAL OF ZOOLOGY. 



many «-ell-known and useful lishes. It is divided into m 
group*, acronding at ventral fins are present or not. In & 
nut ^TX>up — A/wta — there are no ventral fins; andlbriW 
Cimiliar t;)Lam]>le5 are the cominon VxU of our ovm oouiei 
I'hc Eels (Afurimida) have an elongated, ttlmosl cylia ' 
body, with the scales deeply sunk in the skin, and Ecut(t|r| 
parent. A swim-bladder is generally present, and the ( 
IS small and mostly enveloped in the skin. More 
however, than the ordinary Kcls is the GymntVin 
or great Electric Eel, whicli inhabits the manhy 
of thoie wonderful South American pbins. tlie 
"Llanos." This cxtxaordiDory 6»li (fig. uj) is Ixoib ; 




Fi(. It).— ElKlric Ed IC/trttM rtittrinut- 

six feet in length, -•md the discharge of its clcctrii 

is siifficiciitly powerful to kill e\*ca lar^e aninials. The 

lowing striking u^^count is given by Huinbohlt of the nWMt 
in which tht Gymnoti are captured by tlie Indidni.-— "Jl 
number of horacs and miilc* arc driven into a swamp wfckki 
closely surrounded by Indians, until the tinusuol distuitaott 
excites the daring fish to venture an attack. ScriKntJilA 
they are seen swimming along the surface of the waict, ttmii( 
cunningly to glide tinder the bellies of the horses. Bt ^ 
forre of their invisible blows numbers of the poor aninaut «» 
suddenly prostrated ; others, snorting and panting, ihetr nuv 
erect, iheir ^yes wildly Having terror, rtUh madly Cnxi A* 
raging storm; but the Indians, armed with long bcunbooiaA 
drive them back into the nii<Ut of the pool. 

" Ry degrees the liiry of thb unequal contest be^H > 
slacken. Like clouds which have disclurgcd ihcir deOri^ 
ll)e wearied eels dispcfse. They re<iuirc long rest and DwriB- 
i"g food, to repair the galvanic force which tlwy h»t« f 
bvi^hly expended Their shocks gradually become •«*« 
and weaker. Terriiied by the noise of the tnunpling bonA 



TELEOSTEI. 



585 



midly approach the banks of ihc morass, where tliej" are 
cd by h.-irpoons. and dmwn on shoii; by non-coDducting 
) of dry Kxiod. 

kch is the remarkable contest between horses and tsh. 
which constitutes the invitihle but lirinf: weapon of these 
|ants of the waters — that which, awakened by tlie con- 
f moivt and dissiiniUr pariiclcK, cimibtex through nil the 

I of animals and plants — that which, flashing nmid the 
jf thunder, illuminates the wide canopy of heaven — whkh 

to iron, and directs the silent recurring course of 
i«tic needle — all. like the refracted rays of light, flow 
ic common source, and all blend together into one 
all-per^-ading power." 
i ficcxHtd group of the jVa/iuv/i/eri h that of the AtJinni- 
^ which there are ventral fins, and these are abdominal 
jhion. Sjiace will not permit of more here tlian merely 
pning that in lhi:t section arc contained among:tt others 
A-knowQ and important groups of the C/it/aJa {Hening 

^' the Pikes {Esffcida), the Carps, IUfIkIs, Roach, Chub, 
V, &c. {CyfrinhLr). and the SalmatuUc, comprising the 

II species of Salmon and Trout. .Mao belonging to this 
BTc the Sheat-fishes (Si/unJit), which are chiefly noticeable 
K they arc amongst the nnall number of living fishes pos- 
lof siTUCtures of the same nature as the fossil spines known 
Bithyodorxitites." The strui-tiiie in (iiiestion con&ists of 
it ray of the pectoral lins, which is largely dcretopcd, and 
kles a fofmi<Uble spine, which the animal run erect and 
ill (rieuare. Unlike Ihc old " irJith^odoniliies," how- 
Bw Rptnes of the SUurida have their bases modified 
Bculatkm with another bone, and they are not simply 

and impbnicd in the flesh. The "Siluroids" are also 
ibic for their resemblance to certain of the extinct 
I fohcs (e.g., PterUhlhyt, Cixtesifuj, &c.), caused by the 
u the head is protected with an cxoskelelon of dctnial 

The Largest Euro|iean species is the Si/urtu gfanu of 
i)u lakes, and of various European rivers. Another 
ible member of this family is the Afa/aflemros of the 

wen coast of Africa, which is endowed with electrical 

Rl>Blt B. A^ACANTHiM. — This sub-order ia dtMiiK 
by the ha. that the fins arc entirety supported by 
' rays, and never (wssess " spiny " rays ; whilst the ven- 
S are eilhci wanting, or, if present, arc placed under the 

feaib or in advance of the pectorals, and supported ' 
loial arch. The swim-bladder may be wan\in(^>3i4\ 



386 



MANUAL OF ZOOLOCY. 



when pment it docs not communicate with tbe <esofiliagu bf 

tdUCL 

As in ^ preceding order, the AiMmtkmi arc divided ia 
two poups, distioffuished by the pre&encc or Ab&eiMx of! 
ventral {wt. In the first of these groups {Afcu/a) are oclf^ 
few fishes, of which one of the mou familiar examples is i' 
little Saiiit-eel {Ammodyla taiKea), nhi<:h occurs on all 
omsts. In the second grouii {SiiJ>-6ra^Aiit/a) in which ■ 
fins Qxist, arc the two imponant families of the GattiJdi 
P/aavntetida. The Gadiaa or Cod &mily, compmau t 
Haddock, ^Vhiting, Ling, and Cod itself, is of great ymt\ 
man, most of its nicmlKTS being largely consumed a& food 
the Pleurtntntidx or riat-ftshcs arc comprised the Sole, T ' 
Turbol. Halibut, Bttll, and others, in all of which the 
very curious moditicaiion in the form of the body, 
namely, in all ibe I'lat-lishes (fig. 144) is vcjy much < 




Tk. 144— Kaui«o«(lU& Rti-m^m tmHcUlm. Nuninl iba Mm Oa* 

from side to side, and is bordered by long dorsal and anil 
The bonce of the beaid ure twisted in such a manner il 
tiro eyes are both brought to one side of the t>Ddy, wl 
sometimes the right side, sometimes the left. The feh 
kee|)s this side nj>i>ermosi, and is dark-coloured on this 
whilst the opiKWitc side, on which il rests, is white. Fr«i 
luhit of the Mat-gshcs of resting upon one Sat tu£KC 
»dcs are often looked upon as the donol and vcntnl i 
of the body. This, howe\-ci, is erroneous, u ihcy are 
by the i>o«ition oi' the paired (ins to be truly the latiral suited] 
of tlw body. The mouth )ia.t its two sides unequal, the 
lonls ore rarely of the same si/e, the venlrals look tike a 
tinuation of the anal fin, and the bruichiostcgal rays on M 
numbct. 




PDER C. AcAHTKOi^Ritt. — This sub-order is dune- 
by Ui« fact that on« or more of lh« lint rays in the 
in the fonn of true, iinjuintcd. inHcxiblc, " spiny " rays. 
JskcletoR consuls, m a rule, of ctenoid scales. The 
UiE are Kcnemlly bmcaih or in advance of the pectorals, 
<duct ofihe swim-bladder is invariably obliterated. 
lubKjrdcr comprises two Ikmilies : — 
he PMar^ngegimtii, in which the inferior ph.-irynceal 
re anchylosM so u to fotrn a single bone, whith is 
ktmed with teeth. Ilie faintly is not of mu< h import- 
toonly familiar luhes belonging toil bemg the " Wrasses " 

It AaiHthtfttri nri, chanicteri);ed by having atnrays 
jrs in the first dorul fin, and usually in the first rays of 
IT fins, whilst the inferior pharjngcal bones are never 
led into a single mas^ This family includes many 
tate ^rou]», and may be regarded as, on the whole, 
I typical division of the Teleostean fiihes. It will not 
Suwy, however, to do more than mention as amongst 
Ic important fishes contained in it. the Perch family 
i), the Mullets (A/i^id»). the Mackerel family (Stmn- 
the Gurnards ^St/^r0gemiig), the Gobies (Gofiiiifa), the 
I {Slatniidit), and the Anglers {Lophiulee). The Per' 
n by far the moat important member of tliis group, and 
pguiihed \ty having ctenoiil Hcales, the operculum and 
Fcuhmi variously armed with s]>incs, teeth on the vom<T 
Ue a» vretl as on the jaws, and the branchiostegal rays 
e to seven in number. 

WDKK 1>. pLKci'ooNATiii. — This Eub-ordcr is chanc- 
by the faa that the maxillary and prcmoxillary bones 




MS— Otlr>d«IJ<)>. lli>RH<IT>ui>V ll>h«>ir'WibBfwnateiX 



lovably conncacd on each side of the jaw. Tlie endo- 
I is only partially ouified, and the verttbnil ccAumu 
naiiu permanently cartilaginous. The exosVcVe\OB a 



k 



Besiiles ihi; Tniiik-fislics. t 
fislies iJiiilislii/.f) and tin; Gk 

.Sfii-uKor.K K. J.i.ii'iini'.kA: 
portaiit group, mainly cliaraci 
the gills, which are arranged 
arches, instead of the comb-lS 
The eDdoskeleton is only par 
exoskeleton, by way of comp 
The swim-bladder is destitut 

The singular Sea-horses {Ji 
our large aquaria, belong to 
about thenj which requires n 
males in this family are provii 
into which the eggs are plac< 
young, when hatched, can n 
This singular cavity is only t 
at the base of the tail. Mo 
the Pipe-fishes {Syngnatkida] 
monly on our shores. 



CHAP 
CA 



CAKOIDEL 



389 




distinct cranial bones, and ihe loirer Jaw is present Th« 
bkelcton is in the farm of Hinoid scales, ptatct, or spinet. 
re are usually i<in> pain of limbs, in the fbnn of fins, cich 

— "1 UyAa-ny%. Thefirst nysof thefinii arc moMly in ihe 

spind. The pccioral aich has a clavicle, and 

limbs (vcntmJ fins) arc placed close to the anus. 

. fin is mostly unsymmelrical or "hctcroccrcal" The 

bladder is always prc&cni, is ohca cellular, and Is provided 

~i air-duct. The intestine is often furnished with a spiral 
The gills and opercular apparatus are osentiitlly the 
leas in the Bony fishes. The heart has one auiicle and a 
eride, and the iKue of the hnnchial artery is dilated into a 
3US artetiosus, which is rhythmically contractile, is ftimii^ed 
I a distinct coat of siriiited muscular fibres, and is provided 
ti several irjnsvcfse rows of valveB. 

X these characters, the ones which it is most important to 
icmber are the folloning ; — 

L The fu/.^iMf/m is rarely thoroughly ossified, but varies a 
id deal as to the extent to which ossification is carried. In 
Be forms, including most of the older members of the order, 
I diorda dotMilis is persistent, no vertelinil centra arc de- 
l0]>cd, and the skull is can il.igi nous, and Is protected by 
iwkI pbtcs. Even in these forms, however, the peripheral 
ments of the vertebra: are ossified. In others, the bodies of 
t vertebra; arc marked out by osseous or semi-cartilaginous 
igt, enclosing Uic priniilivc matter of the notochoid. In 
Iwts, the vcrtcbne are like those of the Bony fishes — that is 
lay, deejtiy biconcave or " amphica;lous.° In one Ganoid, 
mva — the Bony Pike {Lepid^sleui)~~t\ie vertebral column 
nsists of a series of " upisUiocwIous " vertebrn, — that is to 
fj Tcnebne which are convex in front an<l concave bdilmj. 
■U Is the highest point of developmeni rcitched in the spinal 
lunui of any fish, and its stniclurc Is more Keptili^n than 
tdnc. 

tl. The exoskftftan consists in all Ganoid fishes of scales, 
Itcs, or spines, which are said to possess |Uno<t)' characters, 
ic peculiarities of these scales are that they are composed of 
layers — an inferior Layer of bone and a superficial 

iDgof a kind of enamel, somewhat similar to the enamel 
teeth, called "ganoine." In form the ganoid scales 

generally exhibit themselves as rhomboidal jilates, placed 

to cd^c, withotit overlapping, in oblique rain, the plates 
h row being often articulated to those of the next t^ db- 

processes (fig, 131, li). In other cases the ganoid Ktruc- 
tcs arc simply in tlie form of detached plates, tu\Kic\cs, (n 




390 



MANUAL OF ZOOLOGY. 



sfiines; um) in some cues their f^4/r it eren uiultstia 
froBi the homy scales of the typical TeleosteAn fisbcL In iS 
cues, however, whatever their form may be, they hatv the da- 
tinctivc ganoid structure, being compOMd of an infcriot Ujc 
of true bone wid a sapcnor layer of enamel. It is to U it 
membered, however, that these gaiwid plates and scala «j 
not conliiii;<l to the Ashes of the order Ganoidtt, but that \ 
occur in two tiib-onlcn of the Hony fi&hes — Dundy. Uie . 
tapialhi and t«phcbriim/iii-~xnA in some otbcn of the 'fi 
as wctl- 

III. As to lhc,;&u, both pectorals and vcntrals arc usaaO)'! 
sent,and the vcntrals ;uc always placed Tat back in the neigh 
hood Oif the anus,and are never situated in the immediate ti 
of the pectorals. In lome living and many extinct fonns tbci 
rays of tlie ]uured fini are amuified so as to fofm a int^t r:sBJ ^ 
a centml lobe (fig. 146). IIiIk Htruciure characterises adir 
of Ganoid-sc-iJled by Hiulty.forlliisreasoo, Ow* 
" fringciinn«l.'' The fonn of the caudji fin \-aries, thc4 
being in this respect inicnncdi.i[c between the Boay fiahcii 
which ihc uil is " homocercal," and the Shares ai»d Riiv '^ 
which there is a " heteroeercal " caudal fin. In the tn«jur 
of Ganwds, then, the tail i.f unsyinmetrical or " hetcTOcetal,^ 
but it i$ sometimes c<]ui-lobed or " homocercaL" 

IV. As to ihc sinicturc of the rapiratory ar^ni. the ' 
fishes agree essentially with the Dony fishes, lliey all | 
/i-ff pectinated gills atlschcd to branchial an:hes, and 1 

in a branchial chamber, which is protected by an 
and is closed by a branchioslegal membrane, usually] 
by branchiostegal rays. Besides tlie ofdtnary tinuK 
is &e<iuentlyan adUiiiotial gill, called the " operctibtrl 
attached to tlie interior ^ each operculum, and 
a false gill or " pseudo^ranchia," which receives 
blood only. 

V. There is always a sn-im-bbdder, which is often dji ilrij 
by partitions into several cells, and is always connetti-Jj 
the gullet by an air-duci, as in the Mabcopterotu ditis 
the Telcostftin fislies. 

VI. As to the structure of the keart, the Ganoids dtB 
the Bony linhes, and agietf with the Sharks and Rays in I 
a rhythmicallv contractile bulbus urtcrioaus, which i* fiir 
with a special coal of striated muscular fibres, and is *t\* 
from the vcniridc by several rows of valves (ti^. 141, ' 
TliLs is a decided advance in structure, as in this way i\ 
tertaX bulb is enabled to act as a continuation of rhe vcfiti 

VII. The iMesUnc w. ^Ajcxv tMniished with a spiral reduii* 



CANOroEI. 



391 



cation of JU mucous ineinbTane, forming a spiral valve, such as 
wc tthsli AiitTv/at^ sc« in tlie .Sh^irk.s and Kay^ 

The o«Jci of (he Ganoid fislic* is divi<leiJ Uy Owen intrt the 
two divbiont of the l^fi^gatMiiifi and the Piofi-gatn/uifi. 'I'he 
besiknown living fishes belonging to the Lcpidoganoids an; the 
Bony Pike and the Polypirrm. The Bony Pike (Lffid^tau) 
inhabits the rivers and likes of North America, and attains a 
length of several feeL I'he body is entirely clothed with an 
armour of ganoid scales, arranged in oUiqucly transwrse rows. 
The xenebral column ii exceedingly well ouificd, and is rep- 
tilian in its characters, the bodies Ot the vertebrjf betn^ " opi» 
tbocoeloux" The jows form a long narrow,- snotit, armed with 
ft double scries of Iccth ; and the tail is hctcroccicaL 




«l Ah. AavsiC lh( A»«y> inut«4 mud > obbiI leta ; ' Ona of ihs nntfsl 

The P^jtpteri, of which several species arc known, inhabit 
ibe Nile, Senegal, and other African rivers, and are remarkable 
fee the peculiar structure of the dorsal fin (fiff. 146, A), which 
b broken tip into a number of separate portions, each composed 
of a single spine in front, with a soft Hn attached to it behind. 
Two species of /Wi^/<^ru/ have recently been !iUte<l to poxsesi 
tx/tmaJ brancbia: when young, losing ihcm when fuUy ^rown. 
This observation, if confirmed, n-i!i oHng the Uniioids lOto a 
Dearer relationship with the Mud-hshcs (LcftiiUsirat). Another 
group of Lcpidoganoida is formed by the Trouc-bkc Amia of 
the frcdi waters of the United Sutes. 

TheEccuon/^i!iu^<Mi^ir^*indude3 thebrgeslutii\>ctf.\aa!VCk 



393 MANUAL OF ZOOLOGY. 

of all the living Ganoid fishes — namely, the Stnrgeoni — and it 
also contains some highly singular fossil fonns. The lulKxder 
is defined by the fact that the skeleton is alwaiys impofecdf 
ossified, and often retains the notochord, whUst the head md 
more or less of the body are protected by large ganoid plite% 
which in many cases are united together at their edges bf 
sutures. The tail is heteroccrcaL 

The family Slurionuia comprises the various spedes of Stur- 
geon, which are found in the Nonh, Black, and Caspian sca^ 
whence they, ascend the great rivets for the purpose of own- 
ing. Other allied forms are peculiar to the North Amelias 
continent {f.g; the Paddle-fish, Spatularia), The venebnl 
column in the Sturgeon remains permanently in an embryonic 
condition. The notochord is persistent, and the rertebnl 
centra are n-anting, but the neural arches of the vertebrx reicb 
the condition of cartilage. The mouth is destitute of tndi, 
and the head is covered with an armour of large ganoid pl>to 
joined together at their edges by suture. Rows of detadnl 
ganoid plates also occur on the body. The various spedn of 
Sturgeon attain a great size, one — the Beluga — often measu- 
ing twelve or fifteen feet in length. They are commerciallv c( 
considerable importance, the sw-imming-bladder yielding ni«t 
of the isinglass of commerce, whilst the roe is lately emploiisi 
as a delicacy under the name oi caviare. 

Two or three fossil forms belonging to the Siurionida are all 
that are at present known ; and by far the greater number cf 
extinct Placoganoids belong to the family Oslracosiri, estab- 
lished by Owen, and characterised by the fact that the head 
and generally the anterior part of the trunk as well, was encaseii 
in a sirong annour composed of numerous large ganoid jJaie. 
immovably joined to one another. The posterior extremitj- of 
the body was more or less completely unprotected, and, whilH 
the notochord was persistent, the peripheral elements of itie 
vertebne — namely, tlie neural and hKmal spines— were ossified 
The following are the more remarkable forms belonging to this 
section : — 

(T. Pterii-hthys. — This is one of the most singular of fosai 
fishes, and was first discovered in the Old Red Sandstone t? 
the late Hugh Miller. The whole of the head and the anttriK 
part of the trunk were defended by a buckler of large ganwd 
plates, those covering the trunk forming a back-plate and t 
breast-plate, artiailaied together at the sides. 

The rest of the body was covered with small ganoid seals 
(fig. 148). A small dorsal fin, a pair of ventrals, a pair ofp«- 
torals, and a hetaoteicaX viiV^ti-fiMt ^tusenL The form of 



GANOIDEI. 



393 



llie peaoral fins U the pccultiu-characlcrtsttcorthcyV/T-u'AMi'f. 
Th«« were in the rorm of two long cuivcd spiac^ sonieiliing 
like wings, covered bv finely-tuberculatcd ganoid i)iat&. From 
their fomi, they cannot have been of much use in Kwlmtninf; ; 
but ihey probably, as siiggcsted by Owen, enabled the I'lj^h to 
shuffle along the sandy bottom of the sea, if leli dry ai low 
water. 

fi. Pttratpis. — In moit respect* this genus was not unlike 
Pttnehihyi, but it did nut |)okw:» the pcirnliar pectoral fins of 
the latter. One S|>ccies of Ptcraspis has been found in the 
U|>)>eT Silurian Ko<:lcs (Ludlow), And is as yet one of the earliest 
known indix.-iiionx of the appcaxAncc of the great sub-kingdom 
Vtri^itla ujwn the globe. 

C Cefhalaspis (fig, 147), This, again, is not unlike Pteriih- 
tktt in many respects. The cephalic buckler, however, hns 




pooterior angles produced baokwards, xo as to giv« it the 
r of a " saddler's knife," whilst the pectoral limbs have not 
: fonn of spines. 

CxttvA-jf/ (fi^ 148). — This is another characteristic 



^Benus 
^Ereccdinj 




fift m8 —I. CmttUemt dKifitm : ». PUrirUtfi MllUrl, 



US of the Old Kcd S.miUtone. In thi* genus, as in the 
ig, thexe it a ccphaUc ^^U^jhc plUcs ot wVudv u« , 



394 



MANUAL OP ZOOLOCV. 



covered with small hmtsphcrical luberclcs. The nocedunl 
was pcreisicni, bui the ne\iial and hfcmal spines, and ihf nn 
of ihc tloi&al and vcniral fiDS. arc well ossified. A large txls 
ocetcal lail-lin was doubtless present as weU. 



CHAPTER LVIII. 

ELASMOBRAXCmi AND DIPNOI. 

OSBtt. V. ErASUoDKANCiiii ( -^ Sflafhia, Mullcr; 
Htgiallki Iftloetfkali and Plagi,''itcmi, Uwcit). — This OtkK 
dudes uie Sharks, Rays, and ChinucraN and contspafxb 
the greater and most tyjiicul jjortion of the CMfuJrvftirypitOi 
Cartilaginous fishes of Cuvier The order is dislJiquiibcd l^ 
the following dianicten :— The skull and lower jav Rie*« 
de\-eloped, but there are no cranial bonei, and the skull cm- 
sistx of a single cartilaginous )>ox, without any indieaboti li 
sutures. The vertebral column is sometimes comixncd u'lli'- 
linct vcrtebrsc, sometimcscaTlilaginousorsub-notochonlaL T^ 
exoskeleton ia in the fotm of placoid granulcK, lubetcld. o 
S|iii)et. There are two pairs of fms, repfcaenting the \e^ 
and !iu[)i]ortcd by coTtilasinous fin-rap ; and the ventnl ^ 
arc (>laccd far back near the anuj. The pectoral Arch bu » 
clavicle. 'I'hc heart con«i»t.f of a single auricle and ventridt. 
and the tnilbiis arterlosxis is rhythmically rontractile, i> I*^ 
vidc<I vrtth a special coat of striated muscular librae Aixl u 
furnished with several transver«c rows of valves. The gilk v 
pouch-like. 

In roost of the above characters it will be seen at oooelW 
the Eitume^ranthit agice irtth the Gauoid fislies, especiiflfit 
re^rds the structure of the heart Tlie following puinb 4 
differetjce, however, rciuire more special notice : — 

I. 'llie txitfifMf'ii if what is called by Agawtx "placcii' 
It consists, namely, of no continuous covering of stcalo * 
ganoid plates, but of more or less numerous detacbeii grain 
tubercles, or spines, composed of bony matter, and KtflOt' 
here and there in the integument. In the ejue of the ^f' 
these placoid ossifications often take a very lingular shipt 
consisting (fig. 131, {) uf an osseous or cartilaginous disc, ftoB 
the upper surface oi which springs a sliarp recurved ipiM 
oompoMd of dciiline. 

II. Tlie gilli are lixed and pouch-like, and differ very inW- 




ELASMOBRANCIIII. 395 

'ftoot thote of the liony and Gnnoid fithts. In the case 
' Shniks and Ka>-s, the stnicuirc of the gills is as follows ; 
-^l"!)): btitnchiol arches arc lixcd, and the branchial lamiiMO 
arc not only aiuchcd by their bavs to the brandiial arcbea; 
but arc also fixed by Uic whole of one margin to a scries of 
panitkins, which divide the branchial chamber into a number 
of distinct pouches (fijj. i^q). Each ])diriition, therefore, ca^ 
ries a series of bnmdiial Lunina: attached to each side Uke 
the leaves of a book. By means of these scpa a soics of 
bniKhial sacs or pou<:hes arc- formed, each of which opens 
internally into the pharynx by a separate slit, and communi- 
cates externally with the water by a separate aperture placed 
on the side of the neck (fig, 149, B). The arranfjemcnt of the 
gills being sucb, there is, of course, no gill-oover, and no bran- 
chiostegal membrane or rays. In one section of the order, 
however — viz., tlK Haheef-kali — though the inlernal structure 
of the gilb is the same as the above, ibcre is only a single 
branchial aperture or gill-slit (xttrHaily, ami this is protected 
by a ludimcDtaiy operculum and branchioslcgal rays. 





ria. iM— A KfA «f Ptkbl I>>C'll>li {S^ht*i\ ihiwii^ Ax mni«cnc meulh «• 
IDC Hadcr •urtKe nf iV h«d. viij the iHitiirt4 vi Ihc gil|.poiKh«^ I^ l>4tfrMI 
«( <h* wiMnM tt i>H nn'^uthn: t* Kiitnul (ptrium; H A|ia(ia« linlioi 
bnihtpkwTw: " (Ull'iw*, «iMiUinlac tlw lUcd silk. 

III. Another character in the Elasm^raMhii, shared, how- 
ever, by many of ihc (>anoids, is the structure <^ the intestinal 
canaL The intestine is extremely short ; but, to compensate 
far this, there is a peculbr folding of the mucous membrane, 
constituting what is known as the " spiral valve." The mucous 
ffietnbrane, namely, from the pyloni^ tu the anal aperture, is 
folded into a s]>iral reduptiralion, whicii winds in cl»»e coils 
rouiKl the intestine, like the turns of a screw, liy this means 
the absor]>tivc surface of the intestine is cnormou&Iy incrcaKd, 
and its shortness is thus compensated for. 

The order E/afHutrane/iii is divided into two sub-orders — 
the /fctaafiiiii, characterised by the mouth being terminal in 
position, and there being only a sin;;legill'Slit; and ihtPiagu- 
demi, in which tlw mouth is tramversc, and pbced on the 




396 



MANUAL OF ZOOLOGY. 



under sorlan of the head ((ig. 149, A\ uid there aie Kvetd 
branchial apertures on each Kklc of Ihr neck. 

SUB-oBUER A. HoLocKpHALi. — This HibordcT ilKtlMla CQ- 
tain cutious fishes, of which the only liring forms an tltt 
ChinmriJa. The notochord is penisteni ; but the ncual 
Mchcs and tnmn-ente processes are canib^nous. The \xn 
arc bony, and are coi-ered bjr broad niates reprenentiiig tht 
teeth. The exoitkelcton conxbu of pucoi<) gramiles. Tie 
fint n.y of the anterior dorsal fin in in the form of a powcrfjl 
defensive spine, like the " tchthjrodonilites " of many (wd 
fishes. The ventral fins are abdominal, and the tail is hctrm- 
ocrcaL There is only a single cxtctiul giU-apcmur, covcnd 
with a gill^ovcr and brattchiosiegal membnuic ; bta 01U7 1 
small portion of the bofdeta of the btanchtal laiainx is bvt 
I'he moiil}! is placed ai the exireniiiy of the head. 

The bctl-known living rept«senutive of the ^ub-order ij Ha 
Chimara mmutrota (fig. 150, B), commonly known at tht 




IV 






(Aflo'aMK) 



" kinfc of the Herrings." In CAiman there a only one if 
fiarait gill-slit, but the gills rmlly adhere to tb« inicguiMDl If 




ELA5HOBRANCHII. 



a Targe portion of their border*, and (here ar« consequcnily 
five hole* communicniing with the gill-slit A nidimcniary 
opcTcuKim is present, covered by the skin. In ihc clouly- 
allied Ci^hrhyHtkut from the South Seas, there is a larse fleshy 
appendage at the end or the snouL In the Secondary and 
Tertiary Rocks arc found several fossil forruit, constituting the 
^nera EJaphoJui. Ehstnodus, and lidthfdus. 

Sub-order B. Plat-iostoui. — 1'hi.i wub-order n of consider- 
ably |p«ater imjiortance, ax it includes the well-known Sharks 
anil Ray*. 'Hie vertebral centra arc tisunlly more or less ossi- 
fied, nml even when (luite cirtilaginous, the centra are marked 
out by dtiitinct ringx. The skull is in the form of a cartila- 
ginous capsule, without distinct cranial liones, The mouth ix 
transverse, and is placed on the under stuCace of the head (tig. 
149, A). The cxoskeleion consists of jibcoid granulex, tuber- 
cles, or spines. The branchial sacs o|>en exiern.-itly by as 
many ilisiinct apertures as (here are sacs, and Iheic is no oper- 
culum. A jKiir of lubes pro'-ced from the pharynx to open 
on the upi»er (.uriice of the head by two apertures, which arc 
terroed " sptracks.'' Uy means of these water can be admitted 
to the phat^-nx, and thence to the gills. 

Y^ Professor Owen the Plagioiiomi are divided into three 
sectjons, termed respectively the Ct^rafhori, the Stia<hii, and 
the Saltdts. 

a. Catra^ri. — In this division there is a strong spine in 
front of each dorsal fin, and the back teeth are obnisc. The 
only living rcpiesenMiive of this group is the Port Jackson 
Shark {Ostni^'i Philippi), chiracteiiscd by its pavement of 
plate-like cni^tng teeth, adapted for comminuting small Mol- 
luscs and Crustareani. It is exclusively an inhabitant of the 
iliaa SOS, and is rcnurkable for its dose resemblance to 
group of extinct forms, of which the best known are 
genera HyMta and Aa-odut itata the Second.-uy Rocks. 
Sdathii. — This group comprisea the formidable Sharks 
•Ad Dog-fishes, and is charactcnsed by the lateral position of 
the branchiie on the side of the neck, and by the fact that the 
pectoral fin« have their ordinary form and position. The Dog- 
~ ihcs arc of common occurrence in Dritish seas, but are of 
c value. Their egg-cases are frequently cast u|) on our 
ihorcs. and arc ^miliarly known as " Mermaid's purses." The 
true Sharks are not infrequently found in various Euroiiean 
sea*, twt they arc mostly inhabitants of warmer watera. One 
of the laisest is the "White Sh^irk" {Cardtiriat j-u^rii), 
which aiuini a length of o\-er thirty feet (fig. 150, A), The 
body ia the Shatki {Sfualidte) is not ihomboidal, but is eloor 



I iuscs an' 
^Unstnli 

■the gene 

•Ad 

the 
pec 

"iho; 




398 



MANUAL OF ZOOLOGY. 



gated ; the nostrils are placed on die under side frf flie nont, 
and the teeth are arranged in sevend rows, of which the ouW- 
most alone is employed, the inner ones serving to replace the 
former when worn out, 

c. Batides. — This group includes the Ra}rs and Skitei, lod 
is distinguished by the fact that the branchial apertura m 
placed on the under surface of the body, forming two rovi of 

openings a little behind ibe 
mouth. In the typical meiB- 
bers of the group, the bodf 
is flattened out so as to fonn 
a kind of rhomboidal diK 
(fig. 151), die greaterputof 
which is made up of the 
enormously-developed pec- 
toral fins. Upon die uppa 
surface of the disc are tbc 
eyes and spiracles ; upon 
the lower surface are the 
nostrils, mouth, and bno- 
chial apertures. The flat- 
tened bodies of the Ray^ 
however, must be carefidly 
distinguished from those of 
the Flat-fishes {Pleunm.-. 
tida). In the former, the 

Fia isi— Balid™. Eaia margiiutia, frae of flat SurfaCCS of the bodV aK 

G^!)"" *""""' °'"""'^ "^' truly the dorsal and ventral 

surfaces. In the lattCT, is 
before remarked, the body is flattened, not from above down- 
wards, but from side to side, and the head is so twisted that 
both eyes are brought to one side of the body. The tail in 
the Rays is long and slender, usually armed with spines, and 
generally with two or three fins (the homologues of the doistl 
fins). The mouth is paved with flat teeth of a more or len 
rhomboidal shape. 

The typical members of the Baiides are the Skates and 
Rays, of which the common Thomback {Raia Jarata) may 
be taken as a familiar example. More remarkable than the 
common Rays is the Electric Ray or Torpedo, which has the 
power of discharging electrical shocks, if irritated. The identity 
of the force produced in this way with the electricity of the 
machine has been demonstrated by many careful experiments. 
The Torpedo owes its remarkable powers to two special or^s 
— the " electrical organs," which consist of two masses placed on 





DIPNOI. 



39? 



Hch ^dc of the hesd, and consiHiing each nf niiin«rou.<t vertical 
reUtinous colnmnt, scparatett by nii:int>mnouK Kc}>la, :uid richly 
umishcd with ncrv« from the eighth juir ; the whole anuiige- 
ment presenting a singtil-tr rcionbUncc to the cclUof a vtdtaic 
t»ncT>'. There is no doubt, however, hut that the forec which 
ts expended in the pcoducilon of the electricity is only ncrve- 
Ibrce. For every equivalent of electricity which is generated, 
the lUh loses an equivalent of nervous energy ; and for this 
reason, the pro<tuel>on at the electric force is strictly limited by 
the amount of nerve-force possessed t^ the animal. 

Othci well-known member* of the family are the Sting-ray« 
{7>yffm},\ltv I'Uglc-ray»(.*/>Ai'*ii/»>), the Homed Rays(CyWrt' 
ib^A-ii), and the Kecked Kayi (RAin^batis). 

In the Saw-fish {Pristit OHti'iuorum) the body has not the 
typical Aallcned form of the Kays, and the snout is elongated 
)0 as to form a long sword-likc organ, the sides of whldi are 
furnished with Wong tooih-likc spmcs. Tliis constitutes a 
po«L-rful weapon, mth which the Saw-fish attacks the largctt 
marine animals. 

Before leaving the £!asiin>f<niHefiii, a few words may be said 
as to their position in the class of fi\lics. From the cartiUg- 
ioous nature of the endoskclcton, and the Ktmitarity between 
the form of their gills and those of the Lampreys and Myxin- 
oids, the ElaimetnuKhii vim long placed low- down in the 
scale of fishes, to which also the permanently heterocercal txil 
CDDduced. When we come, however, to take into considera- 
tion tlie xum of all their characters, there can be little hesita- 
tion in [itaciiig the onler ncariy at the summit of the entire 
clas& The nervous .iy*tem, and especially the cerebral mass, 
is very tniKh more highly- develo]>ed proportionately than is 
the case with any other division of the fishes. The organs of 
tentc axe, comparatively speaking, of a very high grade of 
OfnaisUion, the auditory organs being more than ordinarily 
eUMnie, the eyes being wmctimes furnished with a third eye- 
lid (mfinir\tiiii nUtilam}, and the nasal sacs having a very com- 
plex nrticiure. The structure of the heart agreei with that of 
the Gtnoids, and is a decided advance upon the heart of the 
more typical l>ony fishet. Finally, the embryo, before iu 
cxclaiion from the egg, is furnished with external filamentous 
biSBchiic, this being a decided approximation (o Hit Am^Mia. 
OXOUK VI, Dt^Noi i - I'rvtafitfri, Owen). — 'ITiis order is 
1 very email one, and mcludes only the singular Mud-fishes 
{L^ikatirtH) ; but it is nevertheless of greJi importance as 
exhibiting a distinct transition between the fishes ani! the Am- 
fhiiu L So many, in fact, and so striking, arc llie points of 

Ik 



400 



MANUAL OF ZOOLOGV. 



rcwmblancc bctn-ccn the two, thai until recently the tjfiJ.-nm 
(fti!- 151) was Alw3)-f made to constitute the lowcU i\i!a<i 
\heAmphiirki. Thchighcsintithorities, honrcvcr, nowcoooiiB 
placiiijf 11 amongst the fishes, of which it constilulcs the taigbet 
order. The order Dipnat is defined by ihc followinn cbx- 
octent :— ^The body is tUh-Ukc in shape. There b a iktiU inib 
distinct cranial bones and a lower jaw, but the noiochord ii 
persistent, (in<l there are no vertebra] centra, nor on ocdpitil 
condyle. The exo»kekton consists of small, homy, ovctli^ 
ping scales, h;tving the " cycloid " cliaracter. The peaca) 
and ventral limbs are both present, Init have the form of vA- 
shaped, filiform, manyjointed or]^anK, of which the former aalf 
have a mcmbr.-inous fnngc infenoily. 'I'hc ventral Utabs ut 
atiached close to the snus, and the pectoral nrch ha& a dandt; 
but the scapular arch Is attached 10 the occiptit. The biodct 




extremity of the body is ftSngcd by a vertical me<lian fin. Tht 
heart has two auricles and one ventricle. 'I'hc rcspinituj 
organs arc twofold, consisting, on the one hnnd, of free fib- 
mcDtous plls contained in a branchial chamber, which opcnt 
externally by a single vertical {[ill-slit; and, on the other luni 
of true lungs in the form of a double celluLtr air-bladder, coo- 
municating with the WKophagus by means of an air-duct or 
trachea. The branchiie are xupported u[)oa bnuw^hial xtAa, 
but these are not connecled with the hyoid bone ; aru) m *cm 
casex, at any rate, ruiiimcniary fjiiernal branchtx exist as "dl 
The nasal sacs open posteriorly into the throat 

If these characters are examined a little more minutely, ii if 
easy to point to those in which the tepidosirm approaches ibf 
Fishes, and to those in which it resembles the Amphibiau 
It resembles the Fishes in the shape of the body, and in the 
possession of a covcnngj of homy overlapping s>cales of the inie 
cycloid character ; wliiUt the limbs are more like those of Jiibo 
than of reptiles. Tlie tin, also, which <^lothe3 the posienn 
extremity of the body, is of a decided fish-like character. "P* 
most marked piscine feature, however, is the prcscDoe of be 
branchiae, attached to branchial arches, and placed in a bruicbi>> 



Rhy, iriiidi I 



DIPNOI. 



401 




ty, vriiidi open* internal]}' into the phar^-nx by a number of 
liis, ami comrounicatcf cxicmally wiih the outer world by 
of a »inglc vertical gdl*slic. 
fn the other hand, the Lepidetirm approximates to the 

iphibians in the following important points: — The heart 
lon&isfs of tkrft cavities, two auricles and a single vcniride: 
True lungs are [wcscnl, with a trachea and glullls, ret\iming 
heir blood to the heart by a dlntinct pulmonary vein, and in 
very respect diw^har^^ing the function« of the Itinps of the 
lighcr Vertebrates, It i» tnic that the lungn of the Ltfidmrm 
re mefely a modification of the swim-bladder of the other 
ishcrt, but the significance of the change of function is not 
ifcctcd by this. Lastly, sometimes, at any rate, there are 
tuUmcntaty external branchisc placed on the side of the necJc 
rius fcsiure, as will be seen shortly, is characteristic of all ilie 
Imphibians, cither pcnnanently or in their immature state. 

Upon the whole, then, whiKt for the purposes of systematic 
Ja»silication the Le^otirtn must be placed amongst the Fishes, 
t \% not to l>e forgotten that many of its characters arc those 
>f a higher cUss, and that it may justly be looked u[>on as a 
nonecting link, or iransiiionji form, bctwecii the two ^eat 
livutoos o( the Fishes and the Amphibians. 

As regards their distribution and mode of life, two species 
U teast of Leptdotirat arc known — (he L. faraj-uca from the 
ktnaaon, and the L. onnaltnt from the Gambia. 1*hey both 
nliabit the waters of marshy tracts, and a]>|)esLr to be able in 
Iw dry season to tniry thenuclves in the mu<l. fonning a kind 
H chamber, in which (livy remain dormant till the return of the 
niDt. Recently there has been discovered in the rivers of 
DuOTfialand (.Australia) a tish which has been described under 
Hie name of CtratMltu (?) Fosleri, and which would appear to 
be very closely related to the Ltpidotirtn. This singular fish is 
from three to six feet long, and has the body covered with 
hrge cycloid scales^ The skeleton is notochordal, all the bones 
remaining ]>em)anciuly cartilaginous. 1'here is a wdt-devctoped 
(»peTculum, but — a.s in Lepithiirm — no brand) iostegal rays. 
I'hc tail ii homocercol, ant! the pectoral and ventral tins are 
Bupporled t>y a median, many jointed, cartilaginous rod, with 
BamcTOui lateral branches on each side^ 'llie ncan consists of 
• tingle auride and ventricle, with a "Ganoid " hulbus arteri- 
<Hu&. There arc fire branchial arches, of the 1'elewtcan type, 

tcartiUginous. I'hc swim-bladder is single, ooniponcd of 
synraetrkal halves, ccltulsi m structure, with a pneumaltc 
. and glottis, as in Ijpidotirm. The intestine has a spiral 
e, aod there are no pyloric caeca. 



402 



MANUAL OF ZOOLOGY. 



Upon the whole, l>r Gunther oondudcs that the Difiii tic 
to be regarded as a simple sub-order of GAnoids, and ihii ihc 
entire order GamiJet cn.\y be united with the £Jasiiuiramkt 
into a %mg\e order, called Pa/aiehthya, i;h3ractcris<.-d bj hitiiif 
a "heart with a contractile bulbus arteriosus, intestiBe inib i 
spiral valve, and opitc nerves Don-decussating." 



CHAPTER UX. 



DISTRIBUTION OF FISHES IN TIME. 

TiiK geological hi»toty of Kshcs prnents some points of | 
interest. Of all the classes of the great sub-kingdom 
bmla, the fi^hos are the lowest in point of organisatioiL 
might therefore have been reasonably eipected that Uiey < 
present us with the first indications of vertebrate life upon I 
globe; and such is indeed tlic case. After passing throuclii 
enormous group of depoxiu known as the Laurcniun, Ha 
nian, Cambrian, and tx>wcr Silurian fomutions— rcpr 
an immense lapse of time, during which, so (ar as we ret kaflvl 
no vertebrate animal had been created, »c find in the l'fl*| 
Silurian rocks ihc first traces of fish. The earliest of 
Britain, is found in the base of the Ludlow todts (I 
low Shale), and belongs to the placoganotd genus 
.^so in the Ludlow rocks, but at the summit of theirl 
division, are found fin-spines and shagreen, pro)»blr L __ 
to Cestraciont fishes— 'that is to say, to fishes <A at 
grade of organisation as the ElasmoArafuAii. So abtli 
the remains of fii^hcs in the next grt-at geological epoch— r 
the Devonian or Old Keil Sandstone— that this period ' 
freiiuendy been designaictl the "Age of I'ishcs." .\{i>r 
the fishes of the Old Rcii Sandstone belong to tlie 
oiJti. In the Carboniferous and Permian rocks « I;.: . 
the Palieosoic period, most of the fishes are still Canoid, MJ 
the former contain the remains of many Ptagiostomoas AiiiA \ 
At the close of the Paleo«Hc and the commet>cement<'ib(] 
Mesozoic epoch, the Ganoid fishes begin to lose that pieilMi^j 
nant [losition wliich they before occupied, though they cMliMt I 
to be represented tlirough the whole of the Mesoxoicand K^l 
oMiic peiiuiU up to the present day. The Ganoids, ihert*« f 
are an instance of a family which has endured thnM|fc I 
greater ]mrt of geological time, but which early attafatd I 




DISTRIBUTION OF FISIICS IN TIME. 



403 



lum, tnd has been slowly dying out ever since. Tou-aids 
of the Mcsoroic period (in Ihc CrelAccoas period) the 

at family of the Tcteostcan or Bony lisJies 1$ for the ftnH time 

o»ro certainly to have made its appcaniDce. The Tamilies 

the Miu-iifiiroMtkii, PAarynge^rtiiMi, and Dipnoi, liave 

left, so far as is known, any traces of their existence in 

:t time. jud^iDK from analogy, however, it is highly pro- 
le that the two fonncr of thetic must have had a vast uiti- 
□uily, ami il ix not impossible that the so-called "ConodonU" 
Eratn the I Jiwer Silurian rocks of Russia may yet be shown to 
be the homy teeth of fishes allitd to the Lampreys. At pre- 
Bent, however, the weight of evidence is in favour of looking 
Upon these problematical Utile bodies as probably referable to 
Boroe of the Imvrttdrata. 

Leaving these unrntresented order* out of consideration, 
Ifae following are the cnief bets ax to the geological dtsliibu- 
tion of the other great grouju : — 

I. Gammda. — As far as is yet known with certainty, the 
oldnt representatives of the fishes belong to this order. The 
vrder is nrprcscnicd, namely, in the Upper Silurian rocks 
by the reioains of at least four genera. In tlie Devonian 
■Dcks, or Old Red Sandstone, the ttan<»id.i attain their 
ouubmum both in |)oint of numtwrs and development. The 
FUcogaootd division of the order is represented by the 
iingular )|;ciKn Pttrkklhyt (tig. 148), Cfphalaspis (lig. 147), 
JHtraspii. and Csaoitetts ^%. 148). The Lepidoganoid division 
«f the onler is non- also abundantly represented tor the first 
titnc, the genera Dipirrttt, Osteclepis (fig. 146), Olypt^tfis, 
JS^^y<MitiS, £Hpku«Hlhm, and many others bclongirg to this 
■ectMH). As regards the further disiribution of tlie Placogan- 
«ids, the scciion of the OstraeosUi, characterised by the great 
<levelopincnt of the cephalic buckler, appears to have died 
4Mt at the close of the i}evonian jieriuiL The other section, 
Ikowcvcr — namely, that of the SturicnUa — b represented in 
ihc I-iaanc period {Mts&s&U) by the genus CheflirMleus, and 
ia tlic Eocene {Kaiwi^U) by a tnie Sturgeon, the Aeifetiter 

Tnc I^idoganoids continue from the period of the Old Red 
in great profiision, and they arc represented by Tcry many 
Ipoera in the Carboniferous and Permian rocks. In the earlier 
portion of the Mesoioic period— *>,, in the Lias and Trias — 
ffcey arc siill represented, but all the forms arc as yet hetcrocer- 
cd, la the Oolitic rocks, for the first time, Lcpidoganoids with 
)>«&i>cercal tail.s appear, and they continue to be represented 
m^ to the present day. 



404 



MANUAL OP ZOOLOGY. 



II. ElAtnu^aiukii. — like the Ganeidei, the great ordffi 
the ShArk* and Rays \% one of vast anti(|uit)'. At the topof t 
Upper Ludlow rmki, or at the dose of the Upper SilitnB 
epoch, there havo been discovcicd the icmains of undooblcrf 
Plagiostomoiis fishes, moBl nearly allied to the existioi !\« 
Jadtson Shark (CettrttaoH Phiiiff'i). 'I'hc5c rctnaiiu couai 
diiefl)' of defensive spines, which formed the first rayi in di 
dorsal fins, and u|)on these the genus On<hus Kok been fonadfd 
Besides these tliere have heen found i)onions of tkia a 
" shagreen," with tittle placoi<l luber«:kx, hke the skb tf i 
living shark. Thwc have hecn referred to the ^enus Sf l uifim, 
They arc the earliesl-knon-n remains of Plngiostomous f ' 
and with the exception of the few renuiRB from the 
Ludlow rocks, ihcy arc the earliest known remains of i 
the straliiicd scries. The discoveiy of these rcinoiai, i 
time the cailicit known traces of Vertebrate life, b due to 1 
genius of Sir Roderick Murchison, the .luthor of ' Stlum.' 

Most of the fossil Eiatm^ramhii helon); to the dimiaiJ 
C<slriiphori oi a-Kvxx, so called bet^uuse they are provided «d I 
the laij^c fin-spines, which are known to geologists as "ichAffl 



-MlUtlUWtUUUii 



'yjffwutuf 




-^^io^J^lS^ 




nHttw: *. T>H<h of /■fltailMbu; j. /•mmmtdmit i ClvWftiA m . AUf* 
Cudmufcrou RMkt ^^^ ' 

donilites^" The two families of tliis division — the Cttnoe^ | 
and Hybodonis — are lai^ely represented in pait time, ^ 
former chiefly in the Paleozoic period, the latter chirfy to iW 



DISTRIBUTION' OF FISHES IN TIME. 



40s 



ECnc rocks. Subjoined is an illu<(tniiioD of the " ichthyo- 
allies " and leetli of u>inc ol the I'alKoxoic Catrafk^u 
The tnie Sharks are rcpicxenlcd in the later Mesoxoic dc- 
tits if-X; by teeth of NvlUianui in the Oolites) ; but they arc 
ieflv Teftiaij. llie tcclh of Odmtasf^s, Galt<fcerdo, and 
taandoti, arc good examples from the tlocene of ihe Ulc of 
ppey. The true Rajrs arc older than the true Sharks, the 
trbonifcrous fossil, PievraaiUkui, being probably t)ic spine of 
a Ray (fig. 153). Numerous remains of Rays, chiefly tii the 
form of the |>uvcnien(-like teeth, arc known, both from the 
Secondar)' and Tertiary' rocks. 'I'he last division of the Etas- 
witf^raHfhii — vii., that of the H^loc/phali, is poorly represented 
AD past time by the Mcsoioic and Kainozoic Jschiiiaui, Eias- 
^B^wi, (tiuuu/ut, and Edaphodus. 

^■lll. The Bmy or TdeoittaH Fishes do not make their ap- 
pcanncc sooner than the CretJiceous period — that is, towards 
d^ close of the Iktcsoioic epoch. From this time on, how- 
^hr, Bony fuhes with cycloid or ctenoid scales are the chief 
^^resentatives of the wbole chus, and the order appears to 
have attuned its maxiinuni in our present seas. 



406 



DIVISrOM I. ICHTHYOPSIDA- 



CHAI'IER LX. 

CLASS It^AMPHlB!A. 

The class Amphibia comprises d)e Frogs and TiMdk 
Salainandrotds, the Cmiliet^ and the cxtina L^s^ ' 
and \axf be lircfly defuied as follows : — As is the ci« 
the FtshcK, tlie embryo is »ot furnished vrilh an txm». 
the urinary bUdder is the only rejiresentative of die iSnM 
As in Fishes, also, braiuhia &r fiiamtTits adafttd fer tmi^ 
air dissohtd in W9Ur are aki^ys dfvdsped upon tkt rs3^ 
arthis fw a iftger or ihorlfr time. On ihcolherhanl* 
Amphibians differ from ihc Fishes in the C»ct that Inuiuv" 
ahoayt framl in the aJull : Ihe limbs are nefer taitfaid^ 
6hs ; and when meJian /as are present, ,u is sametimei^^ 
these are never /umisha tt'ith flnrajs. The limbi, whoi [• 
sent, exhibit in their skeleton the ume pAris as do theW 
•f the higher Vertebrates. 714^ skull ithiviyi artieulala ^ 
Ihe -.•erttbral oflumn by means */ Aiw Dteipttal etmAyia. flj 
heart {enlists t^ two aurieia and a tingA tientritie. The «■ 
saes (pmmnnifiUe posteriorly with Ike pharynx : and the «■* 
ureters, and duels of the repraduetht srgans epien int« a *■* 
(hamber or "dDoea." 

The great and distinguishing character of the AmfHIrl} 
the fact that tliey undergo a meiamttrphasis after ihuii cxcW* 
from the cjtg. They commence life as water-breaihiDg Itf* 
j>rovit]ed with jplb or braiichiie ; but in their adult fWeiW 
Invariably [lossess lungs — the branchix in the lii{;her fi^ 
disappearing when the lunus are deveU>|>etl— but being in '^ 
cases permanently retained throughout life. 

In the earliest embryonic condition the branchie st i^ 
trrnal, placed on the side of the neck, and not situited i* • 
inicmol chamber as in Fishes. In some cases the euf^ 
bronchia: only are present, and they are, in anycaACthcp* 
whidi ore retained in those forms in which the bfa&dus" 
permanent i^Perennibranekiala). In the tailed Ke/^^ 




[l^rni/a), and in the Frogs and Toads (Ancura), vao sen of 
plis are developed — an external set, uhici) is very soon tost, 
and an internal set, whkh is retained for a lonjier or shorter 




He- IM— Haiwii //^•VwaMi«w.iin«DrihtTrM'ft«Ct((IWCOBEk(T). 

As maturity is approached, true lungs adapted for 
air arc developed. T)ie development, liou-ever, of 
the lungs varies with the completcnens with which aerial resin- 
ration has to tie accomplial>ed ; being highest in thote forms 
which loflc their gilb when grown up (Cadtuihratuhiaia), and 
lowest in thoK in which the branchiic arc retained throughout 
tifc {PerawibraiKhiata). 

In accofdance with the change from an aquatic or branchial 
to a more or less completely aerial or pulmonary- mode ol 
respiration, considerable changes arc effected in the course 
and distribution of the blood-vessels. In the lar\'al condition, 
when the icsptration is entirely effected by means of the gilb. 
thtf drcubtion is carried ou veiY much as it is in Fluiea. 
The heart is composed of a single auricle and ventricle and 
the blood is propelled through a bulbus arteriosus and bran- 
chial artery to the gills. I'he aerated blood ts then collected 
in the t>r:t»i:hi»l veins, and instead of being returned to the 
heart, is forthwith proiieltcd to all ports of the body, the de- 
scending aorta being lormed out- or the branchial veins. At 
tUa stage, therefore, the heart is a branchial one, and the single 
(OtitiaciioD of the heart is sufficient to drive the blood through 
both the branchial and systemic circulations, just as we saw 
was permanently the case with all the Fishes except lh« Lt^x- 



408 MANUAL OF ZOOLOGY. 

dosiren. The pulmonary aTtcrics are at first verj smaD, nd 
take their origin from the last pair of branchial utcriei 
When the lungs, however, are developed, and the ropinticB 
commences to be aerial, the pulmonary arteries increase pto- 
poTtionately in size, and more and more blood is gndnDf 
diverted from the gills and carried to the lun^ so that Ac 
branchiae suffer a proportionate diminution in size. In tb(M 
Amphibians in which branchise arc permanently retained {Fir- 
ennibranchiata), this state of affairs remains throughout life- 
that is to say, a portion of the venous blood is sent by die 
pulmonary artery to the lungs, and a portion goes to thegillL 
In those Amphibians, however, in which the adult breathes bf 
lungs alone {Caducibrancki^a), further changes ensue, la 
these the pulmonary arteries increase so much in size that thcf 
ultimately divert all the blood from the bianchix, and these or 
gans, having fulfilled their temporary function, become atrophied 
and disappear. The vessels which return the aerated blood fron 
the lungs (the pulmonary veins) increase in size proponionatdf 
with their increased work, and ultimately come to open into 
a second auricle formed at their point of union. The hean, 
therefore, of the Amphibia in their adult state consists of /w 
auricles and a common ventricle. The right auricle receives 
the venous blood from the body, and the left receives 4e 
arterial blood from their lungs, and both empty their contenB 
into the single ventricle. As in Reptiles, therefore, the ventri- 
cular cavity of the heart in adult Amphibians contains a mixed 
fluid, partly venous and partly arterial, and from this both ihe 
body and the lungs are supplied with blood. 

As regards the digestive system of the Amphibia there is litde 
to say, except that the rectum opens, as it does in Reptiles, 
into a common chamber or "cloaca," into which are also dis- 
charged the secretions of the kidneys and generative oipM. 
A liver, gall-bladder, spleen, and i>ancreas are always preiesL 
Singular pulsating cavities, belonging to the lymphatic st-sico, 
and known as " lymph-hearts," are also present in the ts^ 
Amphibians. 



CHAPTER LXI. 
ORDERS OF AMPHIBIA. 



The Amphibia are usually divided by modem writers inloftff 
orders, the o\d oi&ei L^idola, tLRAn.'^n&va^ the Ltpideiira, 




OKDEBS OF AUPHIBIA. 



409 



being now pUf cd at the head of the Fishes, under the nanw 
of Difiui. \i\i\\%\ (here is a general agrecnieni as to (he 
number and characten of the Amphibian orders, the naniex 
employed to dcHignate ihent are very various, and it really 
matters litde which are adojited. 

OxDRR I. OniioMORritA, Owen {- GymitafAima, Huxley; 
Afcda of older writers ; Ofhid<^UTa<hm). — This isa small order, 
inchiding only certain snake-like, vermiform 'animals, which arc 
found in varioas tropical counlries, burrowing in marshy ground, 
•omelhing like gigantic canh-ni'ornis. They form the family 
Cadhada (so called by Linnscun from ihcir supposed blind- 
ness), and are charactcTi.ted by their snake-like form, and by 
having the anus plat-ctl almo«i at the extremity of the body. 
The skin ix <iuite xoA. but difTcrt from that of the typical 
AmpliibianK in mii«lly having $m:ill honiy iicales eiubedaed Id 
h. Another fish-like character is that ihe vencbra: are amphi- 
ocalous or biconcave, and the cavitiirs formed by iheir apposi- 
tton are tilled with the cartilaginous or gelatinous remains of 
tbc noiochord. The body is cylindrical and worm-like, and is 
coin)>lcteIy destitute of limits. The skin is glandular, naked, 

' viscous, thrown into numerous folds, and containing nu- 




. It;-— 0|iii»wiip*« a5'<J*i'ay"iuiB'*rw, BiMorilwCiKlliUi. miKhxiluctdi 
1 i t' ^mA, ttm^rimt ibt tonguf , tc*lh, achI (AWnul opcnlnp ot tht BUMnli ; m 
1 (IukkI •ponBc (AflcT Dumcril •nii Hilmn.) 

aus delicate, rounded, homy scales, which are dermal in 
dr character, an<l are wanting in St//i^n«fit annuhtnt. The 
libular rami are short, and arc united in front by a sym- 
..Jl^rw. The (eeih are loti^, iharjj, and gcneiaily uraavci-, 




410 



MANUAt or ZOOLOGY. 



and a row of pnUtbe teeth fomiE a co«K«i)tric stnes with tbt 
naxilbuy teeth. The tongue it flcshjr, fixed to the atoaxij 
of the loirer jaw, and not prolTusble (lig. ■ 55}. The hbi tit 
Bumerou^ hut there is ao sternum. The adtilt possesses liu^ 
one of which i* nroaller than the other, and the note npot 
I>ehind into the mouth. The eyei aie rudimcntatr, BOdf 
oonoeoled beneath the skin, or altogether wanting. 

The position ot the Qteiiia wax long doubt/u] ; but tber 
Amphibian character was ultimately proved by the disoovei; 
that whilst the adult breathes by lungs, the jroung pous 
interna) bnnchin:, communictiing with the external woiU bf J 
a branchial aperture on each side of the neck. Onlf 1 lew! 
species of Cttd/ia are known, and ibey are aU inhaUtanu 1 
hot climates, such as South America, Java, Ceylon, aadi 
Guinea €oa«L They sometimes attain a length of several ftetl 

Ordrr II. Ukodrla { = Iiklhyvmorpka, Owen; &■*>] 
At/nr^A^r),— This order is commonly s|>okcn of collcctivdfl 
as that of the "Tailed" Amphibians, from the fact Uut ibe| 
Wval tail is always rcLiincd in the adult. The Ur6d<U 
characterised by having the skin naked, and destitute of ml 
exoikeleion. The body is elongated posteriorly to fom al 
compressed or cylindrit^ tail, which is permanently reiitiixd 
throwbout life. The donaf veitebrx ore biconcave {ampht 
^hitt), or concave hchirul and convex in front (i^iaJi^t9imt>\ 
and they have short ribs attached to the transverse proceiNa 
The bones of the forearm (radius and ulna) on the one hand 
and those of the shank {tibia and ^uh) 00 the other, arc M 
ancUyloscd to form single bones. J 

iu one section of the order — formerly called Am^iftnetX 
— the gills are retained throughout life, an<l the animal \s tllo^| 
fore " perennihranchiaic." In this section arc the /VaAH,! 
Sirot, and Mmdn'anehtu. In the remaining members oftkl 
onler the gilU disappear at maturity, and the animal is lh(I^ I 
fore " cadurilinmchute." In this section ore the liind asill 
water salamanders. One form, however — the Axoloil <f| 
Mexico — >nppears to be sometimes caducibranchiate, tboiBil 
generally pcrcnnibranchialc. The genera Amftkinmt od 1 
Affm/Uffna, alM), exhibit a partially intermediate Male of [Oiti; 
for though ihcy lose their branchiae when adult, they DCTtf* 
thckss retain the brinchbl apertures behind liie head. 

Of the pciennibrancliiatc Urw/ela, one of ihe l>est knovD ■> 
the singubr Pretau {Hypocktkoti) OMguititu (kg. 156), whidi a 
only found inhabiting pools in certain caves in Illyria »>! 
I>jktniatia. It ix of a pale desh-coloor, or nearly whur, «ilh 
three pain of scarlet branchise on each side of the nc^ 1> I 






ORDERS OF AUPHIBIA. 



4" 



ttainS I leoftJLh of about a foot, and has two pain of weak 
limbs, of whidt the anterior have three loet, and the posterior 
only t«-a Prom iu lubiiat, the power of vision must be quite 
unnecessary, ami, » a nmiter of fact, the eyes are altogether 
nidimentary, and are coveted by tlic skin. Several vsrieties 
of Protatt are knoim, and the one figured above has been 
described as a disiioct .tpccics {P. xanthestiOvt). The blood- 
corppu&cics in Prttfvs are oval in shape, and arc laiger than 
tbose of any other Veitebrate animal. 




uMraaJ fcoDchd ud l/iddctyloiM fen-Wbli. 

the Sireniiia, the most familiar are the Sirens and the 
ilotla. The Siren, or Mud-eel, is found abundant]}- in the 
ip< of South Carolina, and attains a lenj^h of three 
The linnchix arc pcniilenl, ami the hinder pair of legs 
thoUy wanting. Two other aperies are known, but they are 
likcwine cymhned to North America. 

'Hie Mexican Axolotl (SirtJan fitci/firme,ftg. 157)15 a native 
of the McJiican lakes, and attains a length of about a foot or 
fourteen inches. It possesses both pairs of limbs, die anterior 
pair having foar toes and tlie hinder i>air five toes. As onli- 
aahly knon-n in its native coimtry, the Axolotl is certjunly 
perennibr.inchiate, and they breed in this condition freely. 
There i* do doubt, however, that individual specimens may 
lo*c their gilts, without thereby s;itfcring .my apparent change, 
eiccpt it Itc one of colour. The Axolotl, therefore, is in (he 
nngnlar potitioo of being somcliines " caduci branchiate," 
vhilM it IS ordinarily "pcreimibmnchi.-itc."* Nearly allied 

* riorestor Manh of Ntw Haven hai recenllf khown Ihit ihc Sirn/^'n 
IkJUmidn of the <r«teni Sctlc* of AtncrioL, ithcn kept in confinement, 
kMw lis p\U, *nd donal and comdal (m*. whilii il dianga much in cotour, 
tad snidcrEoet i-ohoiu minor modifieatioia in nnutnre. Iti babiu. abcs 
frwiBMr t<M aiimiic, and li bMoni«( aiwiarcnily ahMilutclT idcniicai «rilli 
a^vvA^WMM HHffWiimt, B Salononilrald. Thii dluovtiy liai ihtnwn eoQ- 
McnliWdaabi Mwn lh« vklne of (ha diatinction beiw«oi p*rcnoibr*nchiaia 
Mkd «4itdbnadbiate Ampliibuin*, and luu ronderad il p«afa«lilc thai all 
ih* ipedei uf Sindim an: mcich- lamil Silamanden. ai iMig ago nupectal 
by CuvUt. Al itie loinp time, (lie Aiolotl* cenainly Inved irccly whikt in 
p-wtiialnn of iheir bruKhiac. nnd (here B a* yet no proof thai th«y loae 
ibar (tlb whllt( in a Rate of naltiie. 




412 



MANUAL OF ZOOLOGY. 



to the Axolotl is the hlmt^r9»ekus of North Anerict, in 
which ihe branchix arc persistent. AffhiMi^a and iVntijMM, 
OS already tcnaiked, differ from tlie inToa, JuM mentioecd in 
iosing the gills when »dult, but in retaining the cxtenrutl bm- 
chtat apcrtum on the ti<le of the neck. The fanner a 
cxcliiiivcl)- North Atnen'can, whilst the latter is rqircMDCtd 
by (lilKrrvnr hut ne.iriy-rciatcd species in both North Araaia 

and Java. Both pnesesi de 
normal two p«its or Umba. IV 
Javanese ^)et:)ea iMtntf*^ 
ma.\ima) has the gill'slii ^ouA 
in tlie udulL It i^ abuu: datt 
feet ton^, and i* the ooansl 
lining rcbtivc of the czusd 

In ihc second section of lb 
UroiMa, comgidsing those fann 
in which the gilts arccailucoo, 
and both pairs of litnbt » 
a]wa)-s present, arc the Wsw 
nianundeis or Tritons, and Ac 
Land - sabnunders. The Tri- 
tons arc the only cxamplei of 
the .iqiiatic Salamanders ohki 
occtiT in Britain, and crerv au. 
probably, is >ici)uainied «ilJ> 
tlic common N'cwL 

Tlic Water -sfllamandoi « 
Newts (fig. 159) arc ri'tw 
guished from the 1 
Ibmu by bcinx fumi' 
n compressed IttJi-ltkc uil, tnJ 
hy being strictly ovijiar-ici. 
The larvie are tad{iole-ii 
with external bnnchic, *!■< - 
they retain till 3t>out ihcthml 
month, live adult is dcsbtsk 
of gills, and breathes by lunp 
alone, but the larval tail it tf 
tained throughout the lift c^ 
^ Iff— ThtAinkuK.f.'.Min/iW^ftnH) the aninuL The toognr ■ 

hind, and there arc two ro"" 
of palatine teeth. The rore-fecl an: fourioed, the hiatHwl 
nvMocd ; and the males have a crest on the back and nil 





ORDERS OF AMPIIIRtA. 



415 



m 



The dcrclopincnt of the Newts is so like that of the Frogs 

jthai It ks unnecessary to dilate fuithcr uiwn it here ; but there 

these two points of difTerence to be Doticed : — is//y, That 

ic embryonic tail is not cast oS in the adult ; and, n/Zy, That 
the foTe-hnibs are developed sooner than the hind-limbs— the 

vcne or this being the case amongst tlie Ancnra. 





The Uind-sabmaiKlcn form the genus Sahmandra, and are 
' tingutshcd from their atfuutic breihren tw having a cyltndri- 
instcad of n compressed tail, and by bringing forth their 
young alive, or b^ being ovo-viriparous, in which cace the 
lan'ic have sometimes shed their external branchia; prior to 
binh. The head is Ihid:. the tongue broad, and the palatine 
(h in two long scries, llie sltin is warty, with many glands 
cling a water)- fluid. The best-known species is the S. 
of Southern Europe. Anotlicr species {S. a/fiina) 
I upon lofty motintains. The chief thinjt to rctnerober 
111 Ute I-ond-salamnnderit, and, indeed, about all the C/r^ 
a,i% their complete t]i«tinclnc»s from the true l.itards (Zomt- 
hiia). They arc often completely li/anl-likc in form when adult, 
but they alw.tys possess gills in the earlier stages of their cxiM> 
eace. and this distinguishes them from all the L^tccniliant. 

Okkcx hi, Anolra { = BatrMMiit, Huxley; Thtriomorpha, 
Oncn ; Chdotu^trtKhia, &c.) — This order includes the l-rogs 
and Toads, xim) is perhaps best designated by the name of 
Anoura, or "Tailless" Amphibians. The name BafraeMa, 
employed by Huxley, is inexpedient, partly liecausc it is used 
by Owen to designate the entire cJais Amphibia, and partly 
becatue, in oommon tangtuge, it is usual to un<ler»tjind by a 
"Batrachian" any of the higher Amphibians — such. Tor instance, 
a< a Labyrtnthodont. 

The Atwira, or Tail-less Amphibians, are characterised by 
the following points : — The adult is destitute of both gills and 
tail, both of wrfaicb atruau/et exia in the laiva, «'\v\^V >^c Vko 




414 



MANUAL OF ZOOLOOY. 



pairs oflimhs ire always presoiL The skin is soft, and 
arc rarely any iracM of an cxoskdeton. The dorsa} v 
are " i>roc<i:lou>," or concave in front, and are fumbi 
long transverse processes, which uke the place al n\H, 
9n only present in a niditnentai]' (unn. The rndiut and olu 
in the fore-limb, and the tibia and fibula in the hind-btnb, m 
anchyloscd to form single bones (i^ 159). The movlh • 
sometimes edentulous, but the upper jaw has us<ially 
teeth, and the lower jaw sometimes, 'i'hc hind-limbs 
have the digits webbed for swimming, and are generally 
larger and longer tlian the fore-limbs. The vertebral < 
is uion (often veitebnc in the Frogs, but only eight in 
The tongue is soft and ilcshy, not supponed t^- an m hroKk^ 
but fixed to the s)'mphysis of the lower jaw in from. Pi^ia 
a sort of vTilvc over the i}-mpintim ; J/ji/a and /I'l/iw have ibc 
tympanum shown externally; and Bu/if has the tympaaa 
concealed. 




i')j9.— SM«Mci«ri)won<<m«irTac(Jta»>i'A-)»wiatL ^DwolVtMiM 
with laof Inivnnc fWtinifc 

In the adult AiMtra. respiration is purdy aerial, and iicir 
ried on by means of lungs, which are, comparatively spM^ 
well developed. As there arc no moi-able ribs by whtcb iki 
thoracic cavity csn be expanded, the process of icspintitc^ 
somewhat pectiliar. llic animal first cIomis its 
fills the whole buccal cavity with ait ukcn in 




ORDERS OF AMPHIBIA. 



4<S 



strils. The posterior nares are then closed, and by the con- 
lion of the muscles of the cheeks and pharynx the inspired 
llir is forcibly <lrivi:n into the trindnipe tlirough the open glottis. 
"he pToccM, in fact, is one of swaJlowing; and it » jMssible to 
ifiocate a frog simply by holding tts mouth open, and thcreliy 
eventing the piTfomiancc of the above-mentioned actions. 
lerc can be no doubt, also, that the skin in ihcec animals 
ays a ver)- important pan in the aeration of the blood, and 
hat the frogs especially can cany on their respiration cutanc- 
Lisly, n-ithout the assistance of the lungs, for a verj- lengthened 
^ Enod. This undoubted fact, however, ^ould not lead to any 
BredeiKc being f^ven to the ofci^n-repeaied stories of the occur- 
ence of frogs and toads in civities in solid rock, no authen- 
ited instance of such a phenomenon being as yet known u> 

ICC 




1^ ■ltii.--Ilev«Ii>paitiiia' ih* enoiitiMi Ffog (JFa« iturftnh^' a TudiwlE.tjMwl 

t|«am«>, .hiving ilii h.h'I.ti i>il : . oMir iptdmcD. in 'hit)! ihc Ulnd-Itci hiv* 
tBomMtrt : 4 Sicciuiin iii •likb >tl ihc Unit iR DKwil. bul Ihe uQ hi* BM U*s 
vhelly itiKibnL (Aft« BclLJ 

TTic young or larva of the Frous and Toads are familiarly 
knovn as "Tadpoles." The ova of tlie Frog arc deposited in 
S.-WS in water, and tlie young form, upon exclusion from the 
_ , presents itself as a " tailed " Amphiliiau, complctel)' fish- 
ie in ((ma, with a broad rounded hc;id, a .tac-ltke abdomen, 
and a compressed swimming-tail (lig. 160, ir). There are at 
first two sets of gills, one external and the other iniernal. 'Hie 
external branchi.i: {lig. 160, a) have the form of fiUmrnts at- 
tached lo tlie side of the neck, and they disappear very shortly 
after lurlli. The internal branchia; are attached to cartilaginous 
>Khes, which are connected witli the hyoid bone, and they arc 



4l6 MANUAL OF ZOOLOGY. 

contained in a gill-cavity, protected by a flap of internment, 
which ditTers from the gill-cover of fishes in never dcvdopng 
any opercular bones or branchiostegal rays. Within the boa- 
chial chamber thus fonned the fore-limbs are budded f<xth, b« 
the hind-limbs are the tiist to appear, instead of the fore^inb^ 
as is the case with the Urodela. Even after the first appcn- 
ance of the limbs, the tail is still retained as an instrument of 
progression; but as the limbs become fully developed, the 
tail is gradually absorbed (fig. i6o, d), until in the adult it hu 
wholly disappeared. 

The development of the Frog is thus a good illustration of 
the general zoolc^ical law that the transient embryonic Sta^ 
of the higher members of any division of the aninial Idngdoa 
are often represented by the permanent condition of the lowo 
members of tlie same division. Thus the transitory conditiofl 
of the young Frog in its earliest stage, when the branchix ut 
external, is permanently represented by the adult pcrenm- 
branchiate Urodela, such as the Proteus or the Siren. The 
final stage, again, when the gilts have disappeared and the limb 
have been developed, but the tail has not been wholly absorbed 
is represented by the caducibranchiate Urodela, such as the 
common Newt, 

The order Aneiira comprises a considerable number of 
forms, but may be divided into the three sections of the 
Pipida, Bii/onida, and Ranida. In the Pipida, or Surioim 
Toads, there are rarely teeth, and the mouth is destitute of i 
tongue. A singular and hideous species {Pipa Americana) is 
the best known, and it inhabits Brazil and Surinam. In thii 
curious .\mi)hil)ian the e^s are placed by the male on the 
back of the female, in the integument of which, in cell-like 
cavities, the eggs are hatched and the young developed. In 
the aberrant form DadyUtkra the upper jaw is furnished "ilh 
small teeth, and the three inner toes of the hind-feet arc iiir- 
nishcd with nails, as is the case with no other Amphiblin, 
except Siihiniiiiidra ungiiicuhita amongst the Vrcdda. Thii 
curious form is found at the Cape of Good Hope and in Moi- 
ambiijuc. 

In tJie Toads, or Biifonida, a tongue is present, but de 
jaws are not anned with teeth. The tongue agrees with that 
of (he Frogs in being fixed to ihe/rnnf of the mouth, whilst it 
is //-[»■ Ihhind, so tliat it can be protruded for some distanrt 
from the mouth. The hind-limbs are not disproportionatdjf 
developed, whilst the toes are only imperfectly webbed, lod 
the toes of (he fore-limb are free. The skin is warty and glan- 
dular. The comnwTi 'Yaai ^Bufo vulgaris) is on Oicelleiil 




ORDERS OF AUPHIUIA. 



4>7 



intple of this family. The Nalter-Jack Toad is (he only 
»thcr Itrilinh specie*, l>ul about fifty other fonnj are kiiowii, of 
irhich many arc American. 
In [he JinHii/a: the tongue hu the same form ax tn the 
Toads, but the upper jaw always carries teeth. The hind- 
limbs are much laj^cr th.in the forc-limbs, and arc fitted for 
K-iping, whilst the toes arc webbed. The Iocs of the fore- 
limlis are free. The common Fro^' (Jiana ttmporaria) is a 

foot! exiiTiiple of the typical Ramda. I jijfcr than the common 
'rog is llie t.utab]c Fru^ {Rana ttfulmla) of Kur^pe, anil larger 
a^ain than thi* it Ihe Uullfrog {Rata pipinis) of North Amer- 
i<:a. 'l"hc Trcefrogs {Hyla) nrc adapted for a wholly ditfcrent 
mode of life, having the toes of all the feet furnished with tei^ 
minul suckers, by the help of which they climb with ease, 
Tht-y arc mostly found in warm countries, especblly in Ame- 
rica, but one species {Hyh arborea) is European (fifj. 154). 

Okhkr IV. Labvrinthoikintia. — The members u\ this, 
X\\K la«t or<lei of the Amphibia, are entirely exiincl. They 
^<verc BatrachirtDK, probably most nearly allied to the UroJe/a, 
t>ut all of large lixe. and some of gigantic dimensionti, the skull 
of otic species {/AiiyrintAcdvH /agttrri) being upn-ards of three 
fiect in length and two feci in breadth. The L^byrinthodonis 
nvcrc first known to science simply by ihcir footprinla, which 
«vci-c found in certain sandstones of the age of the Trias. 
'I'hcse footprintb consisted of a series of alternate |>airs of 
H^nd-Kliapcil impreMiom, the hinder print of each pair being 
riiiich l.irgcr than the one in from (fig. 161}. So like were 
%|-icsc impressions to the shape of the human hand that the 
vanknowQ animal which produced ihem was at once christened 
^'hfimherium, or " Hand-beast." Further discoveries, however, 
Soon hliowed that the footprints of Ciinrothfrium had been 
Firoduce<l by ditferent species of Batrachians, to which the 
name of l^byrinihodont^ wa« 3p;illed, in consequaicc of the 
c^omptex microscopic strudurc ul llie teeth. 



e 







tyg. l4t. — F»lpriala tf a LabrrinlhnliiDI <CJn'n4*rr/wi), 

The Labyrinth o(! on Is were " salamandrifonn. with relatively 
^B-e»V limbs and a long tail." — fHuxIev.) The vertebral centra 
a.i)d arches were ossified, and the bodies of ihe dorsal venetofc 



4l8 MANUAL OF ZOOLOGY, 

are biconcave (amphicGeloiu). " In the thondc rqpaa tbiee 
superficially-sculptured exoskeletal pUtes, one median and tin 
lateral, occupy the place of the interdavide and davido. 
Between these and the pelvis U a peculiar aimoor, foimed cC 
TOWS of oval dermal plates, wludi lie on each side of llit 
middle line of the abdomen, and are directed obliquelj for 
vrards and inwards to meet in that line." — (Huxley.) 

The head was defended bj an external covering or hdniet 
of hard and polished osseous plates, sculptured on their eito- 
nal sur£ice, and ofVoi exhibiting peculiar, smooth, symmetiial 
grooves — the so<aUed " mucous canals." The ^ull was mi- 
culated to the vertebral column by two occipital condyla 
The teeth are rendered complex by numerous foldings of ftif 
panetes, giving lise to the " labyrinthine " pattern, &iom wbid 
the name of the order is derived. 

The Labyrinth odonts are known to occur from the Cuba* 
ferous to the Triassic or Liassic period inclusively ; but tkj 
are most characteristically and distinctively Triassic 

DisTRiBtmoK OF Amphibia in Time. — From a gedogiol 
point of view, by far the most important of the AmfAMa ait 
the Labyrintiwdontia, the distribution of which has just \iBA 
spoken of The living orders of Amphibia are of much more 
modem date, being, as far as known, wholly Tertiaiy ind 
Post-tertiaiy. The Anoura are represented by both Totdi 
and Frogs in Miocene times, and they have survived to ihc 
present day. The " Tailed " Amphibians are best known to 
geologists by a singular fossil, which was described by its on- 
ginal discoverer as human, under the name of Horns diini 
testis. The fossil in question ts of Miocene age, and it is no* 
knoivn to belong to a Salamander, nearly allied to the giul- 
salamander of Java {Mmopoma). It is termed the Aadiie 
Schaichzeri. 







DIVISION II. SAUROPSIDA. 



CHAPTER LXII. 
CLASS in.~REPTIUA. 



E second gnat divbion of ih* Vertebrate mb-kingdom, 
odiDg to Huxley, is i)ut or the Saurvfiida, compTisiog th« 
pRe|>iilet .-in<l tlic Birds. It is, no doubt, at Ant sight an 
Wt incTixlibk thing that time should be any near bond of 
tionthip between the Birds and the Reptiles, no two cUsseti 
ititnuls being more unlike one another iit habits and ex- 
aJ zppeaniDce. It is, nevenhele»s, the fact that the Birds 
more nearly related to the KqMiies than to any other clasit 
Ite Vtrtebrata, and it will shortly be seen that many aflini- 
iind even transitional forms arc known to exist between 
e KKU WCtions. lite Reptiles and Birds, then, may be 
irally tncladed in a single primary' section of Vertebrates, 
:]) may be called SMitvfitu/,t after Huxley, and which is 
aed by the possession of the followin}- (^haruaeni : — At no 
od cf existence are branchiae, or wjiter- breadline respiralorjr 
ins, developed upon the visceral arche*; ib<: embryo ts 
islicd nith a well-develojied amnion and nllantois ; the red 
Hjsciei »r the blood are nucleated (Ar. 130, t, t); the skoll 
ntUtes wiilt the vertebral column by means of a single 
nlating Rirface or condyle ; and each half or " ramus " of 
kiirer jaw is com]>oscd of several pieces, and articulates 
k the skull, not directly, but by the intervention of a pecu- 
e, called the "quadrate bone," or "os quadraium" 
Si). 

being the common characters of Reptile^ and Birds 
they are collectively diMingiiishcid from other Verte- 
it tenuins to irujuire what are the characters by whit^h 
! dixtingtiisbed from one another. I'hc following, then, 
he characters which separate the Replik-s from the Birds : 
"he blood in Reptiles is cold^that is to say. slightly u.irmer 
n llie external mrditim — owing mainly to the fact that the 
Dtiary and B)'slcroic circulations are always direcUy con- 



notiary and a 



420 



MANUAL OF ZOOLOGV. 



Dcctcd together, eitlter vrithin the hesrt or in iu in 
neighbourhood, so ih.il the body is Eupfilicd with a miuuR i 
venous and arterial blood, in place of |Mirc ancrial 1 
The lerminalions ot the bronchi ai the surfjicc of the la 
closed, and do not comniunicaic vith air-sacs, |>lAc<d ii 
fcreni }Kkru of tlve body. When the cjiidenniii dercloi» I 
Htructures, thcM are in the form of homy plates or i 
never in ihc form of feathers. The fore^limbc m I 
\-arioitt puqxxto^ inclnding in some canes even Right, InH 1 
ore never conslnK'ic<t upon the tygve of the " wings " of B i4j 
Lastly, with one or two doubtful exccptionti, whilst !hr i 
joint is placed bcin'cen the distal and proximal poriionsi 
tarsus, the larutl and metatarsal bones of the htnd-tiitbi 
never anchyloicd into a uogle bone. 

These are tlic leading characters by which Reptiles w^ 
tingubthcd from Birds, but we must not forget tiie ( ' 
tinctivc peculiaHlioi in which Reptiles agree with Bin 
differ from other Vertebrati;* — namely, the imcscncc 
amnion .ind attantois in the embryo, the absence of I 
at all times of life, the possession of only one occi[nu) ic 
uid tlic uriicuUtion of the complex lower j.iw with the uif (■ I 
meaiu of a quadrate bon& 

It is ttow necesMury to consider these characteristics Wl 
Rtptilia a little more minutely. The chvs tnrludet tk "" 
loixi^ and Turtles, the .Snaken, the 1 j^nls. the Crocodil 
a number of extinct forms ; and with the exception of I 
toises and Turtles they are mostly of an elongated cylii 
shape, provided pottcriorly with a long UiL The limU i 
be altogether absent, a^ in the Snakes, or quite nidin 
as in some of tlic LiiuiTds ; but, as a general nile, l>oih { 
limbs are preneni, sometimes in the form of ainltuUto 
sometimes as swimming-paddles, and in some extmct 
inodilicd to suliserve an aerial life. I1ie cndosktictte 
always well ouiticd, and \% never cartilaginous or scmi-onk'] 
gtnuux, at in nutiy f»ltes, and iorae Amphibians. The UJ j 
anicubtes with the .iila.t by a sinjtle condyle. Tlwr lower )•] 
is complex, imcIi hnlf ur ramtix being composed of frooi (nvO j 
s» pieces, united to one another by sutures (fig. i6i). \ft^\ 
Tortoises, however, these are anchyloscd into a vin^le imm] 
and the two rami are also anchylosed. In most ReiKiles, In*"] 
ever, the two rami of the lower jaw are only louvjly umlri' 
in the Snakes by ligaments and muscles only, in the Lio'A 
by til>T< I cartilage, and in the CnwJi/ia by a regular nBirt 
In all, the lower jaw arttculales with t)ie ^utl by a fiBuIn'' 
boQc (fif '^'< ") • ^'' ^ ^^* °'^*^ projects backnfA. ih 



CHARACTERS OF REFTIIIA. 



421 



0[-eninK of ihe mcnilh is crftcn very extensive, and may eveo 
extcntt beyond the bue of the skull. Tcclh arc usually pre- 
heat, but Me not uink in scjuraic sockets or alveoli, except in 




tic I<»—MniHo'»Serpcnl {/>(*«). * Ani<.-iili>I poniDi of ihi Intv j«w i 
* Quadnic hoti* ; t Hqiuinoul ponioa oT 1I14 Mmpflral bona. 

the Crocodiles. In the Tortoises and Turtles alone there »n 
no teeth, and ihc jaws are simply sheathed in horn, constituting 
a kind of beak like that of a bird. 

Ribs are alirnyx ptcscnt and always well developed, but they 
differ much tn form. It is not correct, however, to regard the 
prcvriKC of ribs as separating the true Reptiles from the Am- 
fAi^a. as is sometimes siatciL Some of the most Liiard-like 
of the Amphibians, such as the Siren, possess short but well- 
developed fills, and rudiments of ribs arc traceable in other 
orders ; whilst in the Gedlia they are targe and well de- 
veloped. 

As tefcards the cxoskelelon, all Reptiles have horny epider- 
mic scales, and thej- are divided into two great section* — called 
mpectively Sfuamaia and IjfrUata — according ax the intcg\i- 
roentary skeleton consists simply of these scales, or there are 
OfiscoiH plates developed in the derma as well. In the Tor- 
toises, the epidermic plates imiic with the bony cxoskcleton 
with the true endoskeleton to form the case or box in 
liich the body of these aninuUs is enclosed. 
The digestive system of the Refliiia possesses few characters 
' any s|>cda] importance, except lliat the rectum opens as 
\ Amphibia, into a common cavity or "cloaca," which not 
Jy receives the faeces, but also serves for il»e <lischarge of 

ptodiicls of the urinary and generative organs. 
The Am/-/ in the Reptiles consists of two completely separate 
ttoiclcs, and a vcniriculaT caiiiy, which is divided into two by 
-•a tnoomptctc ponition. In the Ctwodiiia alone is the septum 



423 



MANUAL OF ZOOLOGY. 



betwKD the voitridcs a. perfect one, and ci--cn in theses a a 
bU other Reptiles, the heart consiax /unaiana/Zj' of do moij 
thaD three chambers. I'hc ordinary course of tbe circobiict,] 
where the ventricular septum i& imperfect, U as (oUowi— TkJ 

impure venous blood retureolj 
from the body U, of covrKJ 
[loured by the vcnix avx into iti 
right auricle (fig. lA^, a), mil 
thence into the ventricle. Ik] 
pure srtcrialiscd and ocnul] 
blood tluit has paued thm^l 
the lungs, is, e^fiuilly uf cotmt [ 
)>ouTcd into the left aundc lA 
and thence |iro)>(:lled into lb I 
venttide (t*). As the vcntnn^J 
cavity ix single, and not 
by a complete partition, 
lovrs of necessity that ihcfr iftl 
mixture m the ventricle, miilitM j 
in the production of a nuull 
fluid, consisting partly of vtxat j 
and partly of aitciial faloxLl 
'lliis mixed fltiid, then, ocni|M9 1 
the common ventricular can!}, 
and by this it is driven botiiH 
the lungs (througli the jniltnoiun 
anery), and to the body (throoj* 
R|.,.«>-i>i««n.>,f,h.ct«»l«i<H,l«t'"; *)"*<"»« aom). Co 

RnMllti rrhe niioui tnlcm ■> [iD (lucntlv, in KepllIeK, iMtfl 




iiiV«-i.'^B?«'SK.Ziw^"4 lung* M>d the various tissues 

Ini 



HUB tn 

«™.iiu,iBt) .• lufhi ■■■ride. nc«i*- orcans of the body arc sun, 

Uft auriclt. niciring mnttal UhJ With A miXtUTC Of aiteriU 



inctr, (..nut tai>tivii->«.w*-^i, »enous DiooQ, auQ not WIUl V 

iiriv<ui>)>i>ji).< puioHfuryuutria mixed blood — the luna i ' 

purely arterial blood— -as a '■ 
case with the higher I'tr/efm/tt. In the Crocodiiia, as 
said, the giarlition between the ventricles is a complete 
and consequently this mixture of the arterial and vrnoiu M 
cannot taic place within the heart itself. In these Kepiilekl 
however, a direct communication exists between the pulmiiiurfl 
artery and aorta (the right and leA aortx) by the i«xaIM [ 
"foramen Panixue," close lo the |>oinl where ihc*e vrw* , 
spring rctpectiveJy from the right an<l left ventricle. In ix" 
Reptiles, thtTctotCt liw »i&« wiwx-Mt of anerial blood »ni 




NKU bk«9 pbce u in ihe lower Kefti/ia, though ptotub)/ 
lo so coin|>lete an exienL It ix (htx pcculiaiity of the 
aiUiion in all Reptiles which conditions their Io«r iciniMrsi- 
C, »low rcs[Hr)tk>n, and generally sluggish vital aclioos. 
rtu; long' in .ill Kqitik-^ except the Crocodiles, are less 
Bpktcly cellular than in the Birds and Mammals «nd they 
tn attuo ■ very great size. Id no Replitc is the cavity of 
thonx shut off from thai of the abdomen l>y x complete 
scuUr pirttiioo or " dtaplim^ ; " thou;;h trace* of this 
iciure arc found in the Crocodiles. 'Hie hings, therefore, 
ta extend along tlw whole length of the thooci(:o.3t>dominjti 
■iiy. In no caie are the lungs connected with air-rece|>t;iclcs 
lated in different parls of the body ; and not uncommonly 
re it only a single active lung, the other being rudimentary 
completely atr<)f>hicd (O/hk/M). 

Lastly, all reptiles arc csscnlijilly oviparous, but in some 
cs the rgg^ aie ictitnud niihiii the l>ody till the young are 
dj to be evL'luded, aitd the animals are then ovn-vtvi parous, 
e egg-!i)iell is luiially junlimciit-tike, but sometimes contains 
m or leu calcareous matter. 

F' 

X class ^Wk 



CHAPTER LXIIL 



DIVISIONS OF REPTILES. 
ClIRLONIA AKD Omtt>tA. 



: class Iffptilia 'm divided into the following nine orders, 
irhieh the tint four are represented by living forms, whilst 
snaining five aie extinct :— 

CMoma (Tortoises and Tunics). 1 
Oj^Uia (Snakes). I r , 

laetThlUi (Lizards). ( "■<*<^'- 

(yteodilia (Crocodiles and jVUigatots). ' 

Sautvftfrygia. 

AntrnMiantui. ) Extinct 

/fcvWtfWMO. 

Deitifiiauria, 



!>RDER I. Chblokia. — ^The first order of linng Reptiles is 
t of the CMetiid, comprising the Tortoises and TurtMiS, a&& 




424 MANUAL OF ZOOLOGY. 

distinguished by the following characters : — There ii an oasuna 
exoskeleton which is combined with the endoskdeton to ibtn 
a kind of bony case or box in which ^e body of the aniiDil ii 
enclosed, and which is covered by a leathery skin, or, mon 
usually, by homy epidermic plates. The dorsal vertcbne, «iik 
the exception of the first, are immovably connected togetho^ 
and are devoid of transverse processes. 'I'he ribs are gicsdy 
expanded (fig. 164, r), and are united to one another h 
sutures, so that the walls of the thoradc cavity are immonbtt 
All the bones of the skull except the lower jaw and the hToid 
bone are immovably united together. There are no teeth, lal 
the jaws are encased in horn so as to form a kind of bat 
The tongue is thick and fleshy. The heart is three-chambod, 
the ventricular septum being imperfect There is a la^ uri- 
nary bladder, and the anal aperture is longitudinal or circulu 
The lungs arc voluminous, and respiration is by swallowing lit 
as in the Frogs. AH will pass prolonged periods without lood, 
and will live and move, even for months, after the remo^-alc' 
the entire brain. — (Redi.) 

Of these characters of the Chelonia, the most important lod 
distinctive are the nature of the jaws, and the structure of ilw 
exoskeleton and skeleton. As regards the first of these poiuB, 
the lower jaw in the adult appears to consist of a single piecf. 
its complex character being masked by anchylosis. The supi- 
rate pieces which really compose each ramus of the jaw are 
immovably anchylosed together, and the two rami are alio 
united in front by a true bony union. There are also do 
teeth, and the edges of the jaws are simply sheathed in honi, 
constituting a sharp beak. In the Chdyiiida and Triiin}\-di, 
however, the homy jaws are covered with soft skin, constituting 
a kind of lips. As regards the second of these points, the bony 
case in which the body of a Chelonian is enclosed consiss 
essentially of two pieces, a superior or dorsal piece, generaiit 
convex, called the "carapace," and an inferior or ventra! pi«t 
generally flat or concave, called the "plastron." The carapace 
and plastron are firmly united along their edges, but are » 
excavated in front and behind as to leave apertures for the 
head, tail, and fore and hind limbs. The limbs and tail cm 
almost always be withdrawn at will under the shelter of ibe 
thoracico-abdominal case formed in this way by the caiapaa 
and plastron, and the hend is also generally retractile. 

The carapace or dorsal shield is composed of the foUowiiiE 
elements : — 

r. T/if spinous processes «/ the dorsal tvrteira, whicli arc 
much flaUencd ouv. W^t^W-j iwA fami a. series of broad platei 



DIVISIONS OF REFTILeS. 



435 



1. 'Pie rii>s, which are also much Hatteneil aiid expanded, atMl 
constittilc wlut are know-n at the "coKlal ]>l.ites" (A);. 164, r). 
'ITicy arc (ftncrally eight in niimticr on each »itl<:, and are 
commonly lutited tliroughotit the whole of their lateral margins 
bjr sutures, in some cases, however, they leave marginal 
apertures towards their extremities, and these openings arc 
Simply covered by a leathery skin or by homy plates. 3. The 
margin of the carapace is <:um[)leted by a series of bony plateit, 
which arc called iJie " marginal plates." These are variously 







■d|P 



llht ! ■■ » « , 






iQgardcd as being demul bones belonging to the exo^keleton, 
er as being endoskeletal, and as representing the ouitied 
cartilages of the ribs (in this Last case the marginal plates 
would correspond with what are known as tlie " sternal rihs " 
of Bird^). 

'ITie " plastron " or ventral shield iii lomposcd of a number 
of boay jJaics (nine in number^, ihe nature of wt\Kh\aAQuW 




MANUAL 



ZOOLOGY. 



ful. By some, the plastron is still regarded u n ptaAf-iierA 
oped breast-bone or stcmura. Uy others, again, the OUma 
arc regarded as being wholt}- without a stcmuin, and the 
boDcs of the pUsiron arc looked upon as cxclusivdjr isufB- 
mentiiTy ossiiicuiions. Both the carapace and the plattraa 
are covered by a leathery xkin, or more eencaUy by a tan 
of homy i>lam (%. 165), which roughly corrcspOBil mift 
the Iwny plates below, and which con^itute in some tpecxt 
the " K^oise-shell " of commerce. TTiese tpidmnk pliio. 
however, must on no account be confounded n-ith the irK 
bony box in which the animal is enclosed, and which u {it» 
duccd partly by the true eodvskelctoD and paxtly by ia^ 
integumentary osstA cations. 

The other points of importance as regards the endotkdetn 
arc these :— 

Firstly, 1'he dorsal vertebne are immovably )oioed togethc 
an<l have no traniverte i>Toceoes, the heads of the ribs ufli&ic 
directly witli the bodies of the verielMW. 

Staindfv, The scapular and pelvic arches, supporting At 
fore and hind limbs respectively (Ag. 164, / and /), arc 'Aad 
wilhiN the carapace, SO that the scapular arch is thus iDSidethe 
ribs, instead of being outside, aa it nonnally is. The topulii 
arch conaiKts of tlie shoulder-blade or scapula, and two ottur 
bones, of which one corrciponds n-ith the acromion proce» ^ 
human anatomy, and the other to the coracoid process, oc 10 
the " coracoid bone " of the Birds. The clavicles, as is kU 
the CISC with ihc Crptodilia, are absent. 

The order Chflmia is conveniently divided into three «■ 
tiona, according as ihe limbs are natatory, amphibious, oc lt^ 
restrial. In the first of these, ihc limbs are convened inU 
roost eRtcient swimming-paddles, all the Iocs l>eing united t^i 
common covering of iiile};ument tn this section are the vd- 
known 'I'urtkt ( C^''/i>n/'</<«}, all of which swim with great cane aaJ 
power, but are comparatively helpless upon the land (fig. i*Sl. 
The Ices are of unec^ual length, and the canpace is much ae 
pressed and flattened. The best-knowii sjiccies are the "cdiUe* 
or Green 'rurllc {Chtifnia mydasY the Loggerhead T^ittft 
(Chdmia mouanna), the Hawk's-bill Tiiitlc (C rmMMAi^ 
and the Leathery Turtle (Sp/iargis ccriaeea). The Green Tiiftk 
ia larsely imported into this country as a ddicacy, and oontn 
abundantly in vnrious parts of the Atlantic and Indian Occtas 
The l-Cawk'vbill Turtle is of even greater commercial imp* 
tancc, as the homy epidermic pbtes of the carapace conitiDtt 
Ihc " tortoise-shell " to largely used for ornamental puipcaa 
The Leathery I'urtle is rcnuikable in having the canpM* 




CHELONIA. 



427 



with a ]eathery skin in jtlace of the liomy phtes which 
' found ill other specie*. 

In tlic »ecoml section of ihc CheUnh, in whii h the limbs are 
adapted for on amphibious life, Arc the Mtid-iunlcs or Soft 
Tonoiaes { rnim ivmw), and the Tcmpins (Kmydida), In th« 
Tri^nydda the development of the carapace is imperfect, the 
rilw being c^p.-inded and united to one another only near their 
biUn, and k-ating apertures near their cxtroniiics. The 
entire carapace is covered by a smooth leathery &kin, and the 
Jiomy jaws are furnished with dohy lipa. All the IVionytidts 
^inhabit fresh water and are camit'onni.t in iheir habiisL Good 
examples are found in the So(t-shellcd Turtle (.Tri^uyx fervx). 




a<l the large and fierce Siupptn); Turtle (Ch/Mra tfrpentina) 
rof the Vnited Siatrt ; bill other species are found in Kgypt 
anil in ihc VnfX Indies. The Terrapins (Emys) have a homy 
beak, am) have (he shield covered it-ith epidermic plates. They 
are inhabitants of fresh water, and are most of them natives of 
Amrrica. 

The third section of the Cie/onut comprises only the Land 
Tortoises {TesfudiniJa), in which the limb* arc adapted for ter- 
reRrial progression, ami the feet are fumi.ihed with short nails. 
The carapace is stronjily convex, an<] is covered I>y Iwmy t\n- 
dermic (iuic« ; the hcid. limbs, and tail can be completely re- 
tracted within the carapace- Though t-upable of s»imming, 
the Tortoises arc really toTcstrial anijiuls, vu\ aic &Uu:.'Oi,'j 




42S MANUAL OF ZOOLOGY. 

vegetable-feeders. The most familiar species is the Taladt 
Graca, which is indigenous in Spain, Italy, ancl Greece. A 
much larger species is the Indiiin Tortoise (Ti^tido /n^ka), 
which attains a length of over three feet 

Distribution of Cmelonia in Time. — The earliest-known 
traces of Chelonians occur in the P^mian rocks, in the lows 
portion, that is, of the New Red Sandstone of older getdogitts. 
These traces, however, are not wholly satisfactory, since thir 
consist solely of the footprints of the animal upon the np^ 
marked surfaces of the sandstone. Of this nature is the Ch^ik 
nus Duncani, described by Sir William Jardine in his dassiol 
work on the " Ichnotogy" of Annandale in Dumfriesshire. Tht 
earliest unequivocal remains of Chelonians are in the Oolitic 
rocks (the Chchnxa planiaps of the Portland Stone). Fossil 
CheloTiiida, Emydida, and Trionyada occur, also, from the 
Upper Oolites to the present day, the Eocene period being 
peculiarly rich in their remains. In the Tertiary deposits d 
India (Sivalik Hills) there occurs a gigantic fossil Tortoise— 
the Coloiio<helyi Alias — which is believed to have been cightctn 
to twenty feet in length, and to have possibly survived w 
within the human period. 

Order II. Ophidia, — The second order of Reptiles is 
that of the Ophidia, comprising the Snakes and Serpents, and 
distinguished by the following characters ;— 

The body is always more or less elongated, cylindrical, and 
worm-like, and whilst possessing a covering of homy scales, b 
always unprovided with a bony exoskeleton. The dorsal \a- 
tebrse are concave in front (procoelous), with nidimentar)- Bans- 
verse processes. There is never any sternum, nor pectoral 
arch, nor fore-limbs, nor sacrum, and as a mle there are bo 
traces of hind-limbs. Rudimentary hind-limbs, however, ire 
occasionally present {e.g., in Python and Tortrix). There ik 
always numerous ribs. The two halves or rami of the lows 
jaw are composed of several pieces, and the rami are united 
anteriorly by ligaments and muscles only, and not by cartilagt 
or suture. The lower jaw further articulates with the skull br 
means of a quadrate bone (fig- i6i, a), which is always raore 
or less movable, and is in turn united with the squamous por- 
tion of the temporal bone (" mastoid bone "), which is also 
movable, and is not firmly united with the skull. The supena 
maxitlffi are united with the pra^maxiila; by ligaments vA 
muscles only, and the jialatine arches are movable and anneJ 
with pointed ^ccur^■ed teeth. Hooked conical teeth are alwa« 
present, but they are ne^'er lodged in distinct sockets or alveoli- 
FunctionaUj, l\\cy aie ca^aUi^ q^ -^"tCamiing nothing mtw 




OPHIDIA. 



429 



Ilian merely holdiDg the prey fast, and the Snakes are provided 
with no genuine masticatory ap|iaratua. The heart lua three 
chaniben, two aunclet an<l a ventricle, the latter im]>erlin;tly 
divided into two cavities by an incomplete septiiin. The lungs 
wtd other paired oi^ans are moMly nut bilaterally symmetrica], 
one of each jKtir being either rudimentary or absent There » 
DO urinary' bladder, and the cloacal aperture is transvcr&e. 

Of these characters of the snakes, the most obvious and 
Striking are to be found in the nature of the organs of locomo- 
tion, ['he front limbo, with the scapular arch and sternum, 
arc inrariibly altogether absent ; and the hind-limbs, if not 
wholly n-antinfc, are never represented by more than an im- 
perfectly-developed Jicries of bones concealed within the 
mil vies oil each side of the anal aperture, and never exhibiting 
any outn.ird cudcnce of their existence beyond ihe occasional 
presence of short homy riaws or spurs ("calcana"). In the 
entire absence, then, or rudimentary condition of the limbs, 
the Snakes progress by means of the ribs. These bones are 
alw-jys extremely numerous (sometimes amounting to more 
lh:Ln three hun<lrcd pairs), and in the abience of a Mernura, 
tJiey are. of coiir*e, extremely movable. 'ITicir free extremities, 
in fact, are sim{>ly terminated by tapering cartilages, which are 
attached by muscular connections to the abdominal scales or 
" scuta *' of the integument. By means of this arrjngcnicnt 
the Serpents arc enabled 10 progress rapidly, walking, so to 
spc-ik, upon the ends of their ribs ; tiiuir movements lieing 
mi>di fadliiateil by the extreme raobiliiy of the whole vertebru 
column, conditioned tiy the cup-and-kdl articulation of the 
l>odics of Ihe vertelwK with one another. 

Tlic botly in the Snakes is covered with numerous scales, 
dcvetc^d app.irenlly in the lower layer of the epidermis, and 

vcrcil by a thin, ininslLicent, su|>cnidal |>etlicle, nhich ispcri- 

iMMlly cast olf and rcnen*ed. On the head and along the 
lomen these scales arc larger than over the rest of the body, 

id they constitute what arc known as the " scuU " or shield.t. 

Tlie only other points in the anatomy of the Ofkidia which 
demand ip«dal attention arc the siruaure of the tongue, teeth, 
and cye- 

The ton)(ue in the Snakes is iwohably an organ more of 
touch than of ta^tc. It consixts of twi> muscular 4-ylindcra, 
united to«-ards their bases, but free townrd.s their cxircmilies. 
The bi6d organ, thus constitutc<l, c-an be protruded and 
rctracteil at will, being in constant vibration when protnidedt 
and being in great pan concealed by a sheath when rcttKted. 
regards the cj-c oi Serpents (fig. 166, AJ, \W dtivtt 





430 



MANUAL OF ZOOLOCV. 



pecnliaiitr lies in the nanocr in which it m proiccud txta- 
xiaOy. Then arc no eyelids, and hence the stony uatri^dig 



^^ .: 




'^ 




Fk- iK—A, DB«nB sf lb* (T« •( ■ Smol (dkw CI«Ha>: ■ DaB tf ik *• 

MBTMiBdim Ik* CTt. B, Had tl On 
AhtIh dM MU (mbml ant ilM nlM 






I falMM bat* U Ik* oivo Jair. 



Stare of all snakes. In place of eytlidt, the eye is sttnounltd 
by a circle of scales (t e), to the cimnifcrence of whick * 
Mticheti a layer of transparmt epidermis, which coven ibe 
wliole eye (d), and is termed the aniocuLsr memliranc Tb 
is covered mtitnally by a thin Uyer of the conjunctiva, whitb 
is reflected forwards from the conjunctira covering ihc lull of 
the eye itself. In this way a tJivily or ch-imbcr u focnni 
between the two l.iyvrs of conjunetivn, and the bcUiyiMi 
Becietion by which the eye is moistened is received into ikib 
The outer cpidctrnir laj^cr (antocuhr membrane) covering 
ball of the cjc in front, is periodically shed «ith the rc»t 
eindermis, the animal being rendered thereby bliml for a (e* 
days. The ptipil of tlie eye is round in most i>ii:ikcs. but foas 
a vertical slit in the venomous Serpcnis and in the Boas. 

As rc^rds the dental and maxillary ajiparatus of tkc 
Serpents, tlie following points re<iiiire nodcc : — FinUf, (■ 
consequence of the aiticutntion of llic lower jaw with a 
novable quadrate bone, which is often directed backwmlh 
in consequence of the quadrate bone being connet-ictl willi s 
movable squamosal bone, and in consequence of ilic rami d 
the jaw being united in front by ligaments and muH^les only, 
the mouth in t)ie Snaties \> capable of opciiin{( tu an enoraMM 
wklth, and the roost astonishing feai.i in the wny nf gwallowioi 
can be jierfonned. &n<>w//)-, this structure of the jaws acconk 
exactly with the strtKiiire of the teeth, ttolh concuaioji n 
render the Snakes wholly incapitblc of anj-ihing like mastio- 
tiufl, and at ihc Bam« time capable of swallowing inunesie 




(Br*. The teeth, namely, are simply fitted for 

h<riding the prey, but not in any way Tor dividing 
it. In the noii-vtnomoux and inoki typical Snakes, 
ad palatine bones carry continuous niw^ of tolid 
ih, so that there are four rows above and two below; 
;ier>or niaxilla: arc very long and are not movable. 

the Viperin* Snakes the ordinary tccih arc wanting 
uperior maxilbe, vhilst these bones are themselves 

shortened, and ore capable of being raised and 
It will. In place of the ordinary teeth, each maxilla 
poison-fang," in the form of a long, conical, curved 
I is concealed in a fold of the {[iim when not in use, 
■NeroaE germs or men-c-£angs behind it {ft^. 1 66, B). 
I is perforated by a tube, opening by a distinct aper- 

apex of the tooth, and conveying the duct of the 
obon-gland. (In reality the poison-dua of the fang 
>y an inl!ection of the tooth upon itself, and not by 
lerfoniioti.) This is a i^bnd, probably produced hjf 
tion of one of the Iwccal salivary glands, situated 
1 under the eye on each side, and secreting the fluid 
ders the bile of these snakes dangerous or &iaL 
inimal strikes its prey, the poison-fangs arc crcacd, 
oiaon is forced through the tube which perforates 
y by the contractions of the muscular walls of the 

pautty by the muscles of the jaws. In moat pvison- 
I the kugierior maxillae carry no other leelh except 
'fangs and their nKlimentary suC4:cM0rs, but in some 
t Bit a few teeth behind the fangs ; whilst the pala- 
m always present, as in the harmless species. In 
r TMiotnous Snakes, again (f.g., jVa/a and the Hytlrv- 
! jaws and teeth agree in most c haractrre with those 
■venomous Snakes, but the first niaxtllaiy teeth are 
I the others and form canalicuUted fangs. X^XiXf, 
toTBS tlic terminal maxillary teeth are deeply cana- 
lut are not connected with the duct of any poison- 

r, in all the Serpents the teeth are anchylosed to the 
K never sunk into distinct sockets or alveoli, 
classitkaiion of the OfMiJia is still a desideratum. 
My, in tlic meanwhile, the one proposed by Dr Gray 
. This emineitt naturalist divides the Snakes into 
db-otdert of the Viftri^a and CdHh-ima, the former 
ilv two perforatMl poison - fangs on the sui>crior 
vhiUl these bones in the latter carry solid teeth, 
I or without additional canaliculated (ai^gs. 




453 



MANUAL or ZOOLOGY. 



The SMb-ordcr Vifierina compriEcs the contmoo Irlpm 
( Viptrida), and the Kautcsnakcs (^Crotalida), th« ianusva\ 
tnoatt^ confined to the Old ^^'oI)d, wliiUi tl>e btier or ika^ 
American. The common Viper {Ptiiat ierui), ocwn ti» 
daiiil)' in F.ngbnd and Scotland, and is capable of inlcui 




T\f. Id;,— TV ,V^ H^ft. % Y^wnwm C oh^ftin ShU 

a severe and even dangerous bite, though it is douWU'j 
fatal effects ever follow except tn the case oC chikircn tf I* j 
jects previously debilitated. The Rattlesoakes are i 
natives of Aineniro, and tliey are hi^fhly |)DiK>nouL 
tcemity of the tail in the true KalUesnuke (C>HU^<i 
is furnished with a scries of horny epidennie cells of ml 
Uled pyTamidal shajie, aitJailnled one within the nihcr, i 
tiilinu an appendage which is known as ibe "Mlile" 1 
stnkiRg its prey, ihc R.-itilesn.ikc throws itself inro4«il| 
shakes its rattle, as it docs also when alarmed The ' 
the Viperine Sn.ikcs <fjKs, 166, 168) i* hrond. "xne 
angular in shape, broadwi at its middle, and (hov-s** 
distinct line of demarcation between the hca^l aitd t , 
head, also, is usually covered with sina» 
spersed wi th .lai){ er plates or "smia" 
known n^flflfibbil grovpare tb* 
Itv^rJ^^^^^H^e' Horned ~ 




OPHIDIA. 



the l^lff Adder (Op/A* drt/ArjM> of the Ctpc of Good Hope 
The CoiiArma include for the most part harmJess snakes, but 
together with these are wme of the most deadly of all the 
venomout nutlceit. In accordance with this they are often 
divided into the three sections of the /nneeua, Sutptda, and 
Venfitoia. In the first of these scclions {Inmota), the *ii|>erior 
nuucillx arc j>TOvided with solid teeth only, and there are no 
fangs. In this section arc the common Kinged Snake of I)ri- 
tain and the lk>as and Pythons of warm climates. The com- 
mon Kinged Snake (CWuAfr NA/r/.r) of Britain is a perfectly 
hannlcss ininial which is commonly found in damp siiuations, 
and which Uvcj> mainly upon frogs. Closely alhcd to tliis is 
XViK BUck Snake {fiasaiNiim ^i^nstrictor), which attains a length 
o4 from three to live feet, but is jK-rfcclIy hannless, sofar as 
snan is concerned. The BMdtK oi itou sniJ I'ythons are the 
Isi^est of all living snakes, attaining a length of certainly over 
twenty (eet I'heir bite is perfectly harmless, but they are 
nevertheless highly dangerous and destructive animals, owing 
lo their grejit size and enormous muscular power. They sciic 
ihcir prey and coil themselves round it in numerous folds, by 
Ciphtcning which they gnulually reduce their victim to the con- 
dition of a slujtcless bolus, fit to be swallowed In this way a 
goodsiicd Python or Boa will certainly dispose of an animal 
as Utige as a sheep or goat, and it is asserted that even human 
licings mxs be devoured in this way 1^ large indiviihialx of the 
Ijimity. The Boos ai>d Pythons occur in both the Old and New 
"World, the Pythons, however, all belonging to the Old \V'oiid ; 
and they are amongst the most Ibraiidable of all living Ophidians. 
'I'hcy possess rudimentary hind-limlu terminating in homy anal 
S{niT^, which co-operate with the prehensile tail m enabling the 
animal to suspeitd itself from trees. In all, also, the dental 
apjiaratu.i is extremely powerful, giving a firm hold for the con- 
stnclion of the prey. 

In the section Siafietla, in which there arc canaliculaied 
Cangs placed far back on the superior moxilUc, with smaller 
kulid teeth in front of them, are ccruin unimportant snakes. 
paitl/ a<tiuiic and puily terrestrial in their habits, sad all be- 
longing to the Old U'orld. 

In the group t'Mnuua, in which there are canaliculaied 
langs i>laceid in front of the superior maxilla: with smaller solid 
teeth behind them, are some of the most deadly of all living 
scr|K:nt)>. One of the best known of Ihese is the Hooded 
Snake, or CcAra di Otf^lh {Naja tripudiani). which is com- 
monly found in tlindostan, and is the snake usually carried 
about by the Indian Bnoke-charmers. It varies from vxo Ut 



434 



MANUAL OF ZOOLOGY. 



six feet in length, and tlte nedc can be extetuivdf diliu^ 
covering the heiul like a hood. A ncsirly-.-ilUed iip«dcs it the 
Aai<t Ilajr {lig. xbf) of Exy\A. Also in this scctioa «rc Ac 
venomous Watcr^iuikcs Jffydreffiititi), which l»ave t «» 
pmsed uil, and are adapied for an aquatic life. They vaaiif 
frequent the mouths of riven in droves, and tlief fwim «iJk 
great grace and rapidity. 

A ver)' fjood gener^ cliaracler by whkh the Colubrine taakfi 
nuy W <li.'ttingui)Jie(l froni the Viperine xnaket. is tn the ik^ 
ana armature of the head. In the yifvrina. as bcfere nd. 
the he^id [%«. \(A, i68) is triangular, broadest bduDd,iild 
sci>aratcd from the neck by a more <x less marked iliniwrtj 
in the diamvicr of this latter pan. I'hc scales, too. aiiiid 
cover the head arc of small siie. In the Coltibrine snalui.> 
thi: other hand, the head is not inarkcdly trian^-uLtr, ondp*-^ 
dually tapers aft into the neck, whilst tliu up|>er huriace of it , 




Uiudii <Aft«r Bell) - ■» -» 

head is usually covered wjth large shieUI-likc plates or "tc»' 
(fig. 16S, A). 

Distribution of Oi-iiidia in Timk. — The OpAidia aitW 
knon-n to occur in any P;ib:o»>ic or Mcsozotc de[¥>HL IVt 
earliett-knonn traces of any serpent arc in the Lower Kiin* 
zoic Rocks, the oldest being the- Palavp/iit Mtapiau of Ik 
London Clay of Sheppey. The neaily-aliiedy><r/n^tf{)jKtn> 
of the Eocene beds of BrackleKhain appears (o havelwcs* 
Boa-constrictor-like .tn.ike of about twenty feet in lesfl^ 
Other species aiPaloKifhit have been described from tbeTetwy 




LACfiRTILU 



CROCODILIA. 



Rocks of the United States, and ihe ^nus DrmfAii hks been 
formed for the reoeptioD of another gigantic constricting Se^ 

Em from the name foimalion. In some of the bter deposits 
ve bc«n found the jwison-fiings of a venomous snake. Upon 
the whole, however, the wakes nMut be looked upon as ii com- 
panttiTcly modccn group, and not as one of any great geological 
antiquity. 



CHAPTER LXIV. 



LACERTILIA AND CROCODIUA. 

Order III. Lacertilia. — The third order of Reptiles b that 
of the Lih-fTiUia. coniiiri&ing all those animals which arc com- 
monly known .-is Lizards, togetlicr witli some serpeotifomi ant- 
malit such as ilie BliiMJ'inMniM. The LaartiJia are distinpiished 
by the following characten : — 

As a general nile, there are two pairs of wel)-develo|>c(t 
limbSt but there may be only one pair, or all the litnbs niay be 
^»enL A scapular arch is alwaj-s present, whatever the con- 
<]ition of the limbs may be. An exoskcleion, in the form of 
>ionty scales like thoie of the Snjikes, is almost always pre^nL 
"Tltc vertebrse of the dorsal region are |>roca:tous or concave tn 
front, rarely ainphiaKlous or concave at both ends. There is 
m single traMvene pnjress at each side, and the head* of the 
Tibs arc kim)>le an<l undivided. 'I'liere iit ciihei no sacnim, or 
the sacral vcrtcbrc dn not exceed two in numlnT. The teeth 
arc not lodged in drsiinct sockets, 'llic eyes arc generally 
fumislicd M'ilh movable eyelids, and arc always so in the com- 
pletely snake-tike forms. The heart consists of two auricles 
ontl a ventricle, the latter partially divided by an incomplete 
partition. There is a urinary bladder, and the aperture of tlic 
cloaca it transverse. 

As a general nile, the animals included under this order 
have four well-developed l^s (lig. 169), and would therefore 
be popobrly called " Lizards. " In some (CAir^a) there are 
no hind-feet ; in tiomc {/fij^f) the foic-limbs are nanling ; and 
others (Attgvit, PifMJi'/tui, and Am/AO^vtia) arc entirely des- 
titute of Limbs, thus coming closely to resemble the inic Snakes 
or Ophidians in external appearance. IIksc scrpcntiform 
Liiards, however, can be distinguished from the true Sttakcs, 
wnongu other characient, by the structure of the jaws. In the 
^SdaIcc^ aa before said, the two rami of the lower yvv ui:\ouw\'] 



436 



MANUAL OK ZOOLOGY. 



aniled in front by tigatncnts and muscles, sjkI an 
behind to a movable qua<tn)le bone, whicb is in turn 
witli a nunablc squatnouU, this giving at) enonitotu 
ga]x: to ihci« animals. In (he Liuids, howei-er, cTcn in dot 




fit- 1*>— I<1UI1». 

niott like thv Snakes, the halvei of the lower jair an Mi 
uniled to one another in front ; and though the quadntc hctt 
is usually more or less movable, the j&vn can in no ocK t* 
upuiied to anything like the extent that charactento Ik 

Another good and Mill Rw>reobvioui character is tobciiitJ 
in ^ tbuctvre of the ]>rotectirc coverings of ihc c)*c. Is in 
Snakes, eyelids arc wanting, and the eye is &im|;ily ojvtrttt tj 
a layer of epidtrmis, consticHting the so-called "aniociU 
inembane." In almost all ihc Liurds on the other haail. » 
eluding all the completely snake-like forms, there arc oumUi 
eyelid^ ami in few cases is there any structure comiwaUc H 
the antocular membrane of the tnie Snakes. Lastly, the t^ 
cal Liurd« oil potsos a sternum or breast-botte. but Au> 
wanting in some of the snake^likc forms, so that it canncibt 
Kppcaleid to as a character by which the ZmoH&i an h 
Mporated from the Ofkidia. 

The whole ordct of the Lufrtitia is very often united m4 
the next group of the Crocodilia. under the name of Sav* 
The term " Saurian," however, is an exceedingly roovrtir-J 
one to designate all the Ke|>[iles which apDroach the lT|m:i^ 
Lisards in external configuration, whain'er inctr exact nilM 
may be ; and Iroin this point of view it is ofivn very oscAil H 
applied to many fossil forms, the structure of which ii m4 
inperfcaty known. It b therefore perhaps ticst to ophf 
this term merely in a loose gcr)cr:il sense. 

Tbe 2.aaHtLa arc often tlivided into the two great gnwpt (f 
the FUftim^m* and Btmiu^piiA, occordtDC u the toogue " 



lacertilia and crocodilia. 



437 



biiid and proinisible like that of the Oi>hi<Ii3ns, or a thick and 
fl»hy, and only proirusitrtc wh«n the niouUi in open. These 
cliMincli<H)», however, arc not of any very peat value, anil no 
good genera) amngcmcnt o( the order hu hitherto been pro> 
posed. Here, therefore, it will be suffiricnt to treat very 
shonly of the more imporTani families of the Lxccrtilians. 

The first Etmily of any importance is that of the Chaldda or 
Chalcidian Liiards, comprising a number of snake-like animals 
which have lonx occu|>ied a debatable |)oi.ition. In ihctr ser- 
pentifomt cylindrical form ihew animals cloiely resemble the 
tnie OphiJia, and ihix likeneu i.t still further incresu^ by the 
ab)rcn<:e or rxidimentary condition of the limtn. The scapular 
■ich and slcmum. however, are |>resenl in a rudimentary form, 
uid one or both pairs of limbs may be present. Another 
chancier sepaming the ChaieiJix from the true Snakes is the 
stnicture of the kiwcr jaw, the rami of which arc unite<l in 
front by a symphysU so as greatly to restrict the gape. The 
Chalcidian LiuixU are entirely covered with similar scales 
arranged in rings or whorls ; the tnink paues into the tail 
without any definite line of demarcation, and there is generally 
a laicnl lofl^ttidinal fold or groove- In Chulcida the IhxIv 
is long «Ih1 snake-like, but all the limbs arc present, though 
these arc small, and have often but a single ncll-dcv eloped 
toe each. It is represented in both the East Indies and South 
America. In Cdmto, of Mexico, only the fore-limbs arc pre- 
sent, an<) in t)ie .African genus Bipes only t)ie hind-hmbs are 
prcj^nt. In the AmfAttbatM of South America the tail is 
very short, and the vent is placed nearly at the end of the 
body, whilst there are no limbs. In the Glasx Snake {OfiiU- 
tauruf) of the United States there nre also no limbs. 

The next great family is that of the Sdmu/^r, including a 
number of small Laccrttlians, some of which arc completely 
nuikc-like, whilst others possess two limbs, and others again 
have the nomud two pairs of limbs in a well-developed condi- 
tion. AH posteu movable eyelids, and in all the conforma- 
tion of the lower jaw is. Lacertitian, and not Ophidian. All 
the Scincnidean I.tuurd.i have the body covered by similar 
scaki overlapping one another like the scales of fisl»es, whilst 
the head is protected by larger pbics. The tongue ti free, 
flcsliy, and slightly notched. Of the snake ■ like forms of 
thia group, none is more familiarly known tlun the Ulind- 
worm or Slow -worm {Anguti /ragi/h, fig. i;o), which is 
found over .ihnost the whole of Europe, in western Asia, 
ud northern Africa, and which is one of the most abun- 
-dint of the British iteptiles. The Bltnd--A'uni\ v<^«aiciu» UV 



438 



MANUAL OF ZOOLOGY. 



extenial appearance of Itmbs though the scapohr and pclw 
arches are prcscni in a rudimentary condiiion. lu aMeaaacc 
is compleiely serpcnlifomi, and il is vulgarly regaided u i dm- 
gCToutt and venomous animal, bui (|uile erToneously, as ii b 
even unable to pietce the )iunun skin. It is a perfecily tui» 
leu uiuul, living upon v,-onns, insects, and snail% and t^to- 




fit. >T»— Hk BUdl-nino ';^>((kiiynfi,:u)— aAic 



noting during the winter. It derives its specilk nunc of; 
i/is from the fact lliat when alarmed it stiflena its musda nl 
such an extent that the uil can be readily broken o^tai'ti 
were liriiile. I 

Numerous other small Lizards are refenbte to the Sdiiaii,\ 
but it is only necessary to mention the Skinks thrnuilii 
(ScMfw), in which both pa>r« of limbs are prcseui in a i 
developed state. The Skinks ore found m almost aB 
wanner pons of ihc Old World, and ckscly-allitnl fiinns <Bxli| 
as (he West Indian "Galliwasp") are found iu the New Wo 
The common Skink (fig. 1 71) is a native of Arabu and . 
It attains a length of eif;ht or nine inches, and wu forMlf^ 
used in various diseases aa a remedy. 

The next family is that of tite Laartida, compruug lb 
typical Lizards, in which there arc always four wdl-derekip«I 
limbs, each terminated by five free toes of unequal len^ 
The bw\y \% covered 'w^^.V wAkx, which assume tlte fonn cf 



LACERTILIA AND CROCODILIA. 

Idds or " scuw " over the abdomen and on the head. The 
iit rotindnl. 'Ilie ton^^e is slcn<lvT, bilid, and protni^ble. 
ic only truly BritUh Uiarda are the Sand-licird {Laeerta 




Kf. in.— ni cawaa Slink UWacu tgltlmM^ 

f), and the ViviporouE Lizard (Zivtxa nhifara); and the 
9DeM (brm upon the Continent is the graceful little Green 
{Latrrta viri4ij), which also occurs in Jersey. The 
; of the Old Wotld are represented in America by the 
r, some oT which attain a length of sevcfsl feet, 
^cty closely allied to the true Lizaids are (he i'araHida or 
^itors, which indeed are chiefiy lerarated by the comp^a- 
tlAy trivial fact that ilic ubdomen and head are covered with 
xluuujr Kales, and not with large " Mnita." The tonfpje is 
xitnisible and fleshy, tike (hat of the Snakes. The teeih are 
in a common alveolar groove, which has no iniernal 
ICT ; and thc-rc arc no palatal teeth. The tail has a double 
of carin.itcd scales, and is cylindiic^it in the terrestrial 
, and compressed in those whose habits are aquatic. 1'he 
liton arc exclusively found in the Old World, and are the 
of all the recent La«rtiJia ; the Vnrtuitu NUittieus of 
ot attaininc a length of six feet, and the yaranut bcptNattn 
[sva attaining to as much as eij^t feet. The Safc-guarda 
r) are the Monitory Liurds of the Ne« Work), and axe 
ge siie. 
' CftkoliJtK form a large famSy of Luards, coupriung a 
It Dumber of species, occurring in almoM idl ifoxa kK '^x. 



440 



UANUAL OF ZOOUIGV. 



world. The tongue is Wi-ide, Rat, scarcely notdied at iu fre 
cxireinity. and hardly at all protnisibk. The eyes ue 
with extremely shon lids, the pu[Ml mostly litiisir, but MB^ 
timex circular. The Icetli an numerous, hmail, rotaytattt 
am! implanted on the inner edf;e of the jaw. I'hc ruib Kt 
mostly- hoolceij an<l rclrjirtite, and the (ocs arc furnished bdo» 
with imbricated plates. The animal Is capable of running i" 
the smoothest surlaces, or suspending itself l)ack-<lownwi: 
They feed on insects, and arc found in abundance in tlie i 
pans of both the Old and New Worlds, 

The /ptOfiidcB consiitulc another larsc family of Lit 
slso belonging panly to (he Old and panly to the New Vi'ti 
The tongue is thick, fleihy, notched at iU extremity unlir, udl 
not protm.tible. Mostly there is a dorsal crest, and a goitntfl 
ill raai- pouch. The body is covered with imbricated wakt 
Only one species of the family is Kiiropcan, but the group n I 
icjirL-i«cntcd by numerous species in N. and S. America, An j 
Africa, and Australia. They aa- often divided into '•ftaaii 
iguanas," in which the body is rtai and depressed, and "otc 
iguanas," in which the body is compressed. The meniticn <* | 
the genus J^uana itself (fig. 169) are 4:onrine<l to the No 
World, and are disb&guishcd by having the throat fumiifanl < 




nc 171— HaidaraChnulMBCr. /Wrn&)-^fler On^ 

I Ot fold of skin, the edge nf which ii 
■ tail, too, are furnislied with on ts^ 
crest of pointed scales. The Iguana aitains a length of fto«j 
four to five feel, and though not of a very inviting appeanan,) 
is highly esteemed as food, llie Ba-silisks {Uatiliuut) Iui« 
the top of the head furni»)ied with a membranous sac wlu<^ 
c;ui be distended with air at will. Th« Agamidtt agree wii 
the Iguanas in most respects, but have two rows of tceiii oe 
the hinder inai^it\ u^ ^!tv: \iaJaXii,«nd ihc uil is eovcml ouk 



LACERTILIA AND CROCODILIA. 



441 



ibHcatcd scales. Cooct examples are the Tapayaxin (jljpima 
'Utt/aris) of South America, and the hideous Mv/fi^A h^ri^ut 
Australia. Here aUo beloi^^ the curtutit little Frill Lizard 
'amydaiaitrus) of AuMmlia, which has tlie neck riiminhcd 
each side with a membruioii.i (ilailcd frill, which can be 
ted at will. More renuikable than the true Ii^uon.-is is the 
; Flying Dragon (Draeo vo/a/it) of the iuLsl Indies and 
Archipelago, [n this nnguUr little Lizard there is a 
meinbraoous expansion on each side, formed by a fold 
the integument, supported upon the anterior false rib», whidi 
1 straight out front the spinal column. By means of these 
eral espaiulons of the skin, the DraM vt>/aiis can take long 
ins leaps from tree to tree, anil can pursue the insects oa 
tdt it feeds ; btit the laleral membranes simply act as pam- 
utes, and there is no |)ovrcr of tr\ie flight, propcrljr so called. 
The Inst family of the living Lizards which requires notice 
is that of the Ch^imtrlamtitia, containing the ^miliar little 
Cffiwilfo A/riianus, which occurs abundantly in the nonh of 
Africa and in li^pi, and is so well known for its power of 
changing its cok>ur under inilation or excitement. In ihb 
genus the eye (lig. 173} is of large size, and is covered by a 
single circular lid, formed by a coalescence of the two 1idS| 
aiitl pcrfontcd centrally by a small aperture, by which the 
rays of light reach the pupil. The Chameleon is naturally a 
slii^ish aninul. but it catches its food, consisting of insects, 
by darling' out its long, fleshy, and glutinous tongue — an opera- 
tion which it effects with the most cxtraortlinary rapidity. 

'Hie tail in the Chameleons is round andnrehentile, the body 
ccmipr«is<:<l, and the skin like shagreen. Tne toes arc adapted 
for tne art>oreal life and scuuorial habits of the animal, being 
so arrangnl as to form two etpial and opposahk- sets, The 
lungs are excessively voluminous. The Chameleons are ex- 
(;ecdingly sluggish and slow in their movements, and arc con- 
fiDed to the warmer parts of the Old World. 

DrsTRiBtrrioN or LAccKTiLtA in Time.— Tlic geological 
range of the true Liuerlilia is not by any means very great, 
nor, with a single exception, are their remains of much import- 
ance. The earliest traces of LiiartU in the stratified ^ries are 
feuod in the fresh-water strata of the I'urheck beds at the 
Miiiunit of the JuroMic scries. Several small Li/anls occur 
here, and liave been described under the names of Nalhttti, 
MaatJMvH, Hawil/us, and /ifAimii/vn. 'i"hc most temaikatile 
fiosstl Lizard, however, is the At,}Kuaurtit of the Chalk. This 
^ganiic reptile occurs at the very summit of the Cretaceous 
in what b known as the Maesuicht Chalk, 't^n ^Atjc^ 



443 



MANUAL OF ZOOLOGY. 



is DO lc<» than five feet long; and as the tail atx) limhs wen 
fbrined fur sa-iniming. ihcrc earn be littk doubt but tlui M*ia- 
satma — like the living AmMyrAyHeAus — was afjuatir in i» 
habits, and frequented 3ie scs-shore. Several nhcr RcpuJci, 
either belonging to die genus Mtsasaurvs, or ocarly allied lo 
it, have been deitcribea lirom the Cretaceous and Tmim 
rocks of Nonh Anvenca. Recent researches on these Mow- 
sauTotd Reptiles by Professor Marsh of New Haven hait 
shown that they possessed fin-like p«ddlcs like those of (lit 
Ichthyosaur and Plcsiosaur. 

Ordbk IV. CxocuuiLiA. — The last and highetf onkrcf 
the living ReptU'ta is ihal of the CroadUia. indoutng the liriaf 
Crocxxlilct, Atlli;aloT!i, and Garials, and diaractehsed by dt 
following peculiarities : — 

The 1)0(1)- is covered with an outer epidermic exoekdcM 
composed of horny scaler and an inner dermal cxoakdtUn 
consisting of s<)u.iTe<l bony plates or scutes which may be co» 
lined to the dor^l surface alone, or may exist on the vtninl 
surface as well, and which arc disposed on the liack of till 
neck into groups of different fonn and nunilxr in diilienn 
species. The bone* of the skull and face arc firmly united u 
gether, and the two halves or rami of the lower jaw are unHlj 
in front by a suture. I'here is a single row of teeth, 'm\eA oil 
implanted in distinct sockets, and hollowed at the base for A#J 
germs of the new teeth, by which they are successively ; 
out and replaced during the Life of the animal llie ontn* 
the dorsal vertebrae in all living OimmA/m are proc<sIoM< 
concave in front, but in the extinct forms they may be ciAd 
ampbiccclous (concave at both ends) or opi^thoccclous |cdfr 
cave liehind). The vertebral ends of the anterior tnink-Ai 
are bifurcate. There art two sacral venebne. The cenioi 
vertebne have small ribs (hence the difficulty experienced l> 
the .-inim.nl in luming quickly) -, and there arc generally UkJ 
abdoroinal nbH produced by the ossification of the tetK&fliMI 
intctseciions of the rati muscles. There are no cbncks.] 
The heart consists of four completely distinct and lepintt' 
cavities, tvro auricles, and two ventricles, the ventricular iq» 
turn — as in no other RcjHiles — being complete. 11te right W 
left aortx, however — or, in other words, the pulmonary arlOT 
and systemic aorta— «re connected together close to tbeixorkv 
by a iiniall a]>crture {feramn Panitta), so that the two nos 
of the heart communicate with one another. The aperture ^ 
the clo.ica is longiiudinjl, and not transverse, as in the UaA 
All the four limbs arc present, the anterior ones being pcfln- , 
dacty\ous, U\e \wi.\civoi UUai&u».'fnN&. All are ovipaioui> 




LACERTIUA AND CROCOUILtA. 



443 



The chief potnu by which ihc Crocodiles arc dtMm^iiahed 
from (lieir near allicH, the I^cettiliaiu, are the posseKKion of 
a partial iKHiy drmiAt exotkelcton in addition to tlic ordinary 

M<lcnni<: c-ciTring of soilctt, the lodgment of llic lecih in 




fk' in ftiir'i<flli HMd mi hn-|H>n nf ihc Iwdv al ihc cnnnni OoomIB* 

distinct lockeis, and the fact that the mixture of venous and 
■nerial blood, which it ho ch3ru:terixtic of RrjXilcv takes 
place, not in the heart itxdf, hut in its immediate ncij^libotir- 
hood, by a commtinication between the pulmonary ancry and 
sorU directly after their origin. 

The only other points about the Crocodiles which require 
ipecial ivoiice are that the e>-e5 are protected by movable ej-e- 
Iids ; the car is covered by a movable eai-lid ; the na-tal cavities 
f^»en in front by a single no.icril, and are shut ofl' from the 
cavity of the motith, but open far back into the cavity of the 
pKarjTix 1 and lastly, the tongiie is larcc and Ae.shy, -ind is im- 
movably attached to the Iwttom of the motilh. (Hence the 
belief of the ancients that the Crocodile had no tongue.) The 
tail is long and compressed, with two rows of keeled plaic«, 
whidi unite about ils middle to form a single crest, which is 
continued to its extremity. The feel arc palmate or scmi- 
pftlmaie, atul only the three inner toes on each foot possess 
claws. The eyes tiovtevi three distinct lids, and there are two 
glai*^ under the tnroat secreting a mmky substance. 

The Cmmfi/ia abound in the fresh u-atera of hot coimtriet, 
atkd are the largest of all living Kcptileff, not uncommonly at- 
taining a length of twenty feet or upwards. They are divided 
hy Owen into three sub-orders, according to the shape of the 
dorsal vcTtebm, icnned the Pn&tliit, Amfihieaiu, and Opia- 

Sut-vrAr i. Prvae/ia. — In this suborder are all the living 
BMHtben of the CreeodUia distin^ished by having the bodies 
of the donal vertehrx concave in front fprocceloufi). Three 
diitiiKt types may be dislinguishnl amodgtt the Uvint^ CroM- 




444 



MANUAL OF ZOOLOGY. 



dilia. IV Oavul \% dtstinguUhed liy iM elongated inout. « 
Ihc cslrcmiiy of which the nostril u pUccd, and \>y the (ift 
that the teeth Jtrc pretty nearly equal in sue and simiUr ii 




PIf. 114.— Ckull(i(v*>uniC»rWI/iMlOWM<u<tAcrVwda'|UirMt 

form in the two jaws. In the true Crocodiles (fig. I74)lk| 
fourth tooth in the lower jaw is larger ihnn the oihm.iad| 
fomii n canine tootli. which a received into a notch cicanlal , 
in (he Mile oflhi; alveolar bonier of the u|>]icr jaM', so iKii it it 
visible externally when the month i* dosed. In the Ciunsn , 
or Alligators the »amc Tooth in the lower jaw romiK a i iiini I 
but it is lecetvcd into a pit in the palatal surface of the uitv] 
jaw, where it is entirety concealed when the mouth it ^ ' 
The Crocotliles have the liind-legs bordereil by a tooiMl 
fringe, and the Iocs completely unitcti by tnemhraive. Tho 
are essentially natives of fretli water, but sotnctiino Tro^dK 
the mouths of rivers. They ocnir chiefly in Asia and .Vfna 
but species are found in some of the West Indian IslmK 
The .\lligators have the hind-tegs simply rounded, and llic frfl 
not complclely wcbbcct. They arc essentially atiuatM:. anil Vt 
voracious animals, living upon fish or Mammals. 11»c !«•<■ 
known species are the Alligator of the Southern United SuM 
{A. MisshiippU